Sequential infiltration of Th17 cells into the substantia nigra in a primate model of Parkinson's disease

Sequential infiltration of Th17 cells into the substantia nigra in a primate model of Parkinson's disease | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Sequential infiltration of Th17 cells into the substantia nigra in a primate model of Parkinson's disease Jincheol Seo, Thanh Thi Hai Nguyen, Jinyoung Won, Chang-Yeop Jeon, and 15 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5388540/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Parkinson’s disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra (SN). Recent studies have focused on the dysregulation of CD4+ T cell subsets, including Th17 cells, with nigrostriatal dopaminergic neurodegeneration in PD. Nonetheless, the mechanisms behind the sequential and sustained infiltration of these T cell subsets into the brain during PD progression are not well understood. This study aimed to elucidate the long-term infiltration patterns of Th1, Th2, and Th17 cells in the SN during PD progression. After injecting cynomolgus monkeys with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to develop a non-human primate model of PD, we observed dopaminergic neuronal loss and infiltration patterns of CD4+ T cell subsets in the SN at early, intermediate, and late phases. Th17 cells were observed to infiltrate immediately during the early phase, unlike the delayed infiltration observed for Th1 and Th2 cells. Notably, the early phase infiltration of Th17 cells coincides with the rapid degeneration of dopaminergic neurons. Furthermore, the physical proximity between Th17 lymphocytes and a decreased number of dopaminergic neurons was observed in the SN after MPTP injection. This study reinforces that Th17 cells are associated with neurodegeneration of dopaminergic neurons in the onset of PD. Biological sciences/Neuroscience/Diseases of the nervous system/Parkinsons disease Biological sciences/Neuroscience/Neuroimmunology Health sciences/Neurology/Neurological disorders/Parkinsons disease Th17 lymphocytes Infiltration Substantia nigra Parkinson’s disease Non-human primate MPTP Macaca fascicularis Dopaminergic neurons Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Parkinson's disease (PD) is an intractable neurodegenerative disorder characterized by progressive degeneration of dopaminergic neurons within the substantia nigra (SN) 1 , 2 . Recent studies have highlighted that complex interactions between the central nervous system and immunological processes are critical for the pathogenesis and progression of PD 3 – 12 . A focal point in understanding the etiology of PD is the significance of immunological responses, particularly the involvement of CD4 + T cells and their subsets 13 – 19 . The dysregulation of CD4 + T cell infiltration has been a focus of recent studies because of its association with nigrostriatal dopaminergic neurodegeneration in patients with PD 20 , 21 . The CD4 + T cell subsets that infiltrate the brain during neuroinflammation can be categorized into two groups based on their functions: pro-inflammatory, which includes T helper 1 (Th1) and T helper 17 (Th17) cells, and anti-inflammatory, which includes T helper 2 (Th2) cells. The differentiation and function of these CD4 + T cell subsets are regulated by specific transcription factors: T-box transcription factor (T-bet) for Th1, GATA Binding Protein 3 (GATA3) for Th2, and RAR-related orphan receptor gamma t (RORγt) for Th17 22,23 . Th17 cells, which secrete interleukin (IL)-17A and are implicated in immune-related diseases like psoriasis, rheumatoid arthritis, and inflammatory bowel disease, have been shown to directly cause neuronal cell death 24 , 25 . This highlights the correlation between Th17 cell activity and the loss of dopaminergic neurons in PD 26 , 27 . However, while the dysregulation of Th1 and Th2 cells in PD, particularly regarding peripheral neuroinflammation, has been reported 28 , Th1 and Th2 cells are considered to have a relatively lower impact on PD pathogenesis than Th17 cells 29 , as evidenced by PD mouse model studies 30 , 31 . Nonetheless, the in vivo mechanisms underlying the sequential and sustained infiltration of CD4 + T-cell subsets, including Th17 lymphocytes, into the brain during PD progression remain unclear. It is suggested that the dysregulation of these CD4 + T cell subsets may play a crucial role in the pathogenesis and progression of PD, potentially offering promising therapeutic targets 32 , 33 . This study aimed to elucidate the long-term infiltration patterns of Th1, Th2, and Th17 cells in the SN during PD progression. Using a nonhuman primate (NHP) model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), we investigated the infiltration of these T cell subsets during the early, intermediate, and late stages of PD. Specifically examined were the expressions of T-bet (Th1 marker), GATA3 (Th2), RORγt (Th17), and tyrosine hydroxylase (TH, dopaminergic neurons) in the SN of the MPTP-induced NHP model. Here, we aimed to divide the progression of disease phases based on the onset of PD signs following MPTP injection. Then, we analyzed the dopaminergic neuronal loss and infiltration patterns of CD4 + T cell subsets in the SN of the MPTP-induced NHP model at each phase. This study aimed to provide insights to improve therapeutic strategies targeting subsets of CD4 + T cells, potentially offering innovative avenues for the treatment of PD. Results Assessing progression of PD induced by MPTP injection and behavioral observation We conducted global activity analysis using video tracking to assess behavioral changes following MPTP injections. As previously described, ten monkeys were subjected to repeated MPTP injections until their global activity levels declined to less than 10% of the pre-dose baseline (Fig. 1 ). Temporal alignment was established such that week 0 corresponded to the point at which each monkey reached the minimum threshold of global activity (motor peak). Subsequently, the monkeys maintained diminished global activity levels until sacrifice for histopathological analysis, spanning the early (1 week; n = 3), intermediate (3 months; n = 2), and late (30 months; n = 2) phase, without exhibiting behavioral recovery (Fig. 1 b). Additionally, there was no correlation found between the total cumulative dose of MPTP and the reduction in global activity (Fig. S1 a). Temporal changes in dopaminergic neuron loss and Th17 cell infiltration after MPTP administration To investigate temporal changes in dopaminergic neuron loss and Th17 cell infiltration following MPTP administration, we conducted immunohistochemical analyses to assess levels of TH + and Th17 cells in the SN of saline- and MPTP-injected NHPs during the early (1 week; n = 3), intermediate (3 months; n = 2), and late (30 months; n = 2) phase (Fig. 2 ). Dopaminergic neuron counts significantly decreased in MPTP-treated monkeys across all phases compared to controls (Fig. 2 b). In contrast, Th17 cell infiltration showed no significant increase in the early phase but displayed a gradual and sustained increase in the SN following MPTP administration (Fig. 2 c). Notably, the peak of dopaminergic neuron loss was observed during the early phase, while Th17 cell infiltration continued to increase progressively throughout the study period. No correlation was found between the total cumulative dose of MPTP and the decrease in dopaminergic neurons (Fig. S1 b). Physical proximity between IL-17A expressing Th17 lymphocytes and nigral dopaminergic neurons To investigate the colocalization of dopaminergic neurons and Th17 cells in SN following MPTP administration, we performed immunohistochemical analyses to assess levels of TH+, RORγt+, and IL-17 + cells in saline- and MPTP-injected NHPs (Fig. 3 ). In the MPTP-injected group, physical proximity between Th17 lymphocytes and the reduced population of nigral dopaminergic neurons was observed. This proximity was visualized through co-localization of T lymphocytes and nigral dopaminergic neurons using DAB/VIP staining (Fig. 3 a) and immunofluorescence (Fig. 3 b). Additionally, IL-17A expression in RORγt + cells was confirmed via immunofluorescence staining (Fig. 3 c). Delayed infiltration of Th1 and Th2 cells into SN, unlike Th17 To investigate CD4 + T cell subset infiltration across different phases post-MPTP administration, we conducted immunohistochemical analysis (Fig. 4 ). This analysis focused on identifying T-bet+ (Th1 cell marker), GATA3+ (Th2 cell marker), and CD4 + cells within the SN of both saline- and MPTP- injected monkeys across the early (1 week; n = 3), intermediate (3 months; n = 2), and late (30 months; n = 2) phases. This approach aimed to clarify the temporal patterns associated with PD progression, specifically focusing on CD4 + T cell subsets. The study found significant differences in infiltration between RORγt+ (Th17) cells and T-bet+ (Th1), GATA3+ (Th2) cells during the early phase, as shown in Fig. 5 a. However, no significant changes were observed in the infiltration of CD4 + T cell subsets during the intermediate (Fig. 5 B) or late phases (Fig. 5 C). The line graph in Fig. 5 d, illustrating MPTP-induced PD progression shows the immediate infiltration of Th17 cells, accompanied by a rapid reduction in dopaminergic neurons during the early phase. In contrast, Th1 and Th2 cells exhibited delayed infiltration during the intermediate phase. (Purple dotted line, TH + cells; green line, T-bet + cells, Th1; black line, GATA3+, Th2; brown line, RORγt + cells, Th17). Additionally, no correlation was found between the total cumulative dose of MPTP and the infiltration levels of CD4+, Th1, Th2, and Th17 cells (Fig. S1 C-F). Correlation between CD4 + T cells, their subsets, and nigral dopaminergic neurons in PD Positive correlations between CD4 + T cells, their subsets, and dopaminergic neurons were identified following MPTP administration, as analyzed through linear regression (Fig. 6 ; (A) TH+/CD4+; R² = 0.6604, P = 0.0263 , (B) TH+/Th1; R² = 0.9043, P = 0.0010 , (C) TH+/Th2; R² = 0.8501, P = 0.0031 , (D) TH+/Th17; R² = 0.5965, P = 0.0418 ). This analysis indicated partial recovery of dopaminergic neurons in the late phase compared to the early phase following MPTP administration, as shown in Fig. 2 B; however, dopaminergic neuron levels in the late phase remained significantly lower than those in the saline-injected group. This recovery coincided with increased infiltration of CD4 T cells and their subsets. Discussion In this study, we observed a distinct, sequential, and sustained infiltration pattern of CD4 + T cell subsets in an NHP model of PD. Our findings elucidated the progression of T lymphocyte infiltration in PD, emphasizing the pivotal role of Th17 cells in the early phase (Fig. 2 , 5 a). The infiltration of Th17s cell markedly differed from that Th1 and Th2 cells. Th17 cells infiltrated immediately in the early phase, unlike the delayed infiltration of Th1 and Th2 cells. Notably, the early phase infiltration of Th17 cells coincided with the rapid degeneration of dopaminergic neurons. Additionally, the close proximity between Th17 cells and the reduced number of dopaminergic neurons was observed in the SN of the MPTP-injected group (Fig. 4 ). This observation supports the association of Th17 cells with neurodegeneration of dopaminergic neurons in PD. The association between Th17 cell infiltration and concurrent dopaminergic neuron reduction during the early phase supports previous findings on the critical role of Th17 cells in the development and progression of PD 34 . Th17 cells induced neuronal cell death and upregulated the IL-17 receptor (IL-17R) in an autologous human induced pluripotent stem cell (iPSC)-based model of PD. Although the expression of IL-17R in neuronal cells in vivo remains debated, dopaminergic neurons are known to respond to IL-17A by expressing IL-17R and activating NFκB (nuclear factor kappa-light-chain enhancer of activated B cells). Intercellular adhesion molecules (ICAM) in MPP+-treated mouse ventral mesencephalic neurons interact with lymphocyte function-associated antigen-1 (LFA1) on Th17 cells 35 . Notably, inhibiting RORγt alleviated dopaminergic neuron death in MPTP-injected mice 26 . Therefore, targeting Th17 lymphocytes presents a promising clinical opportunity for PD treatment 25 , 36 . However, further research is needed to comprehensively understand the role of Th17 and other cell interactions in the pathogenesis and progression of PD, given the limited scope of current animal and clinical studies 25 . In the late phase, dopaminergic neurons showed a significant increase compared to the early phase (Fig. 2 b). Although their count remained significantly lower than in the saline-injected group, this suggests partial recovery or long-term preservation of neurons after MPTP administration. The delayed infiltration of Th1 and Th2 cells (Fig. 4 b, 4 c), may contribute to mechanisms supporting this recovery. This points to a complex interplay between different types of immune responses over time, impacting disease outcomes. Additionally, while this study did not fully characterize the interactions among Th1, Th2, and Th17 cells, it highlighted the sequential infiltration patterns of these subsets (Fig. 3 ), with Th17 cells infiltrating in the early phase, contrasting with the delayed infiltration of Th1 and Th2 cells. These observations suggest potential clinical roles of CD4 + T cell subsets in PD progression. As shown previously, specific subsets of CD4 + T cells play peripheral regulatory roles in PD 12 , 37 , 38 . Th1 and Th17 cells are associated with exacerbated PD, whereas Th2 and regulatory T (Treg) cells protect against disease progression. Th1 cells, which secrete interferon gamma (IFN-γ) as part of their pro-inflammatory role, are implicated in the exacerbation of neuroinflammation. Findings suggest that Th1 cells play an important function in PD pathogenesis 30 . A previous study noted an increased proportion of Th1 cells relative to other T cell subsets in patients with PD, implying a potential Th1 bias in the peripheral system 39 . Th1 cells can enhance the phagocytosis of dopaminergic neurons by microglia during inflammation, a process that may significantly influence the pathological development of PD 21 , 40 . Conversely, Th2 cells exert anti-inflammatory effects by secreting IL-4, IL-5, and IL-13 41 . Th2 cells are peripherally decreased in patients with PD compared with healthy individuals, accompanied by altered anti-inflammatory responses 39 . However, similar to Th1 and Th17 cells, evidence on Th2 cells in PD is variable and contradictory, leaving this topic unresolved. This highlights the critical need for more research to comprehensively understand the role of Th2 cells in the progression of PD before making any definitive conclusions 38 . This study suggests that the progression and timing of T lymphocyte infiltration, rather than the cumulative dose of MPTP exposure (Fig. S1 ), are more indicative of the observed changes in PD characteristics. This perspective highlights the importance of considering the sequential nature of T-cell infiltration to understand PD mechanisms more fully. The interaction between CD4 + T lymphocytes, their subsets, and nigral dopaminergic neuron counts may be a key to understanding PD (Fig. 6 ). This correlation implies that immune responses mediated by these T cells could influence the degeneration or recovery of dopaminergic neurons, suggesting a need for further investigation into PD pathogenesis and treatment strategies. This study has limitations due to the immediate dopaminergic neuronal damage induced during the early phase following MPTP administration. Given the gradual neuronal degeneration observed over time in human PD patients, accurately extrapolating T cell infiltration sequences using this MPTP-induced NHP model is challenging. The results of this study suggest a more complex immune interplay across different PD stages. Further studies are required to better understand the relationship between lymphocytes and PD pathogenesis. For example, NHP models that mimic progressive dopaminergic neuron loss and Lewy body pathology through alpha-synuclein overexpression, similar to that seen in human PD, could provide more relevant insights 42 . In conclusion, this study reinforces the association between Th17 cells and neurodegeneration of dopaminergic neurons in the onset of PD. The findings suggest that Th17 cell infiltration may play a critical role in initiating neurodegenerative processes, underscoring the importance of immune responses in PD pathogenesis. Methods Experimental animals and ethics statement Ten adult female cynomolgus monkeys ( Macaca fascicularis ), aged between 4 and 10 years and weighing between 2.8 and 3.5 kg (Table 1 ), were used as described in previous studies 17 , 43 , 44 . All experimental monkeys were maintained at the National Primate Research Center (NPRC) at the Korea Research Institute of Bioscience and Biotechnology (KRIBB), as previously described 45 – 47 . The NHP experiments were approved by the KRIBB Institutional Animal Care and Use Committee (approval no. KRIBB-AEC-20270) and comply with the ARRIVE guidelines 48 , 49 . To prevent potential harm from MPTP metabolites, monkeys were isolated to prevent physical contact, but were allowed visual and auditory contact with neighboring monkeys. The cage dimensions followed the guidelines of the National Institutes of Health (USA) (60 cm × 80 cm × 80 cm). They were provided with commercial monkey chow (Teklad 2050™, Envigo, USA), assorted fruits, and ad libitum water, with rubber and plastic toys for environmental enrichment. Housing conditions maintained a temperature of 24 ± 2ºC, relative humidity of 50 ± 5%, and a 12-hour light/12-hour dark cycle. Veterinary monitoring adhered to NHP research guidelines 50 , 51 . In this study, only female cynomolgus monkeys were used to minimize sex as a biological variable and limit the effect of sexual differences. Table 1 Overview of saline and MPTP administration Group Label Age (years) Body weight (kg) Dose (mg/kg) Total dose (mg/kg) Sacrifice time* MPTP ( n = 7 ) E1 6 2.90 0.2 15.0 1 W E2 6 2.86 15.0 1 W E3 6 3.03 8.0 1 W M1 8 3.22 4.0 3 Mo M2 9 2.98 7.0 3 Mo L1 10 3.48 12.0 30 Mo L2 7 2.83 4.0 30 Mo Saline ( n = 3 ) C7 7 2.85 Saline (0.6–0.7 mL) 12 Mo C8 4 3.29 12 Mo C9 6 2.88 12 Mo * Sacrifice Time: Time to sacrifice post-PD symptom onset (W; Weeks, Mo; Months) Global activity The procedures for measurement of global activity have been described in a previous study 43 . Software quantified movement changes by calculating the rate of pixel change across sequentially captured video frames, encompassing 240 min of recordings for each experimental subject. Global activity monitoring was conducted both before and after MPTP administration and was extended until the sacrifice of each subject. MPTP administration The protocol for administering MPTP injections (0.2 mg/kg; Sigma-Aldrich, St. Louis, MO, USA; dissolved in saline) has been detailed in our previous studies 17 , 43 . In summary, seven cynomolgus monkeys were subjected to daily intramuscular injections of MPTP into the left femoral area, whereas three monkeys received saline injections as controls. The cumulative MPTP dose was adjusted based on the behavioral evaluations of each subject (Table 1 ). To evaluate the behavioral modifications resulting from the MPTP injections, global activity levels were monitored via video tracking. This procedure was continued until the global activity of the seven monkeys subjected to MPTP injection fell below 10% (denoted as the motor peak) of their baseline pre-injection levels. The overall dose of MPTP administered to each subject ranged from 4 to 15 mg/kg (Table 1 ). Subsequently, timelines were adjusted so that 'Week 0' matched the week in which the lowest threshold of global activity ('motor peak') was observed for each monkey. Following the motor peak, MPTP administration was terminated and each monkey was sacrificed at different phases: early (1 week; n = 3; A1, A2, and A3), intermediate (3 months; n = 2; S1 and S2), late (30 months; n = 2; C4 and C5). A control group of saline-injected monkeys (n = 3; C7, C8, and C9) was also sacrificed; notably, these three monkeys were used in a previous study 17 . Tissue preparation All monkeys received transcardial perfusion with 400 mL of 100 mM phosphate-buffered saline (PBS) under profound anesthesia, which was facilitated by intramuscular injections of ketamine (1 mg/kg) at each designated time point 17 . The skulls were opened to harvest the whole brain, which was immediately washed in cold PBS. Then, the brains were post-fixed in 4% paraformaldehyde and submerged in a 30% sucrose solution at 4°C for cryoprotection. Immunohistochemistry and immunofluorescence For immunohistochemical analysis, the brains of all monkeys were coronally sectioned at 30 µm using a cryostat (Leica Biosystems). To block non-specific binding, free-floating sections were incubated in 4% normal horse serum (S-2000; Vector Laboratories) in PBS with 0.3% Triton X-100 for 2 h at room temperature. The sections were then incubated overnight at 4°C with anti-tyrosine hydroxylase (TH) (1:1000, mouse, MAB318, Merck Millipore), anti-CD4 (1:1000, mouse, 317401, Biolegend), anti-T-bet (1:1000, 14-5825-82, mouse, Invitrogen), anti-Gata-3 (1:1000, rat,14-9966-82, Invitrogen), and anti-RORγt (1:1000, rat, 14-5825-82, Invitrogen) antibodies. For secondary antibody application, the sections were incubated with the appropriate biotinylated anti-mouse IgG (1:200, BA-2000, Vector Laboratories) or anti-rat IgG (1:200, BA-9400, Vector Laboratories) antibodies for 2 h at room temperature. For staining and visualization, the ABC method (PK-6100, Vector Laboratories) was used with 3, 3’-diaminobenzidine as the peroxidase substrate (KPL DAB Reagent Set, 5510-0031, SeraCare). In double staining experiments for light microscopy, sections underwent overnight incubation at 4°C with the anti-RORγt antibody (1:1000, rabbit, NLS5188, Novus Biologicals) with DAB staining. The tissues were subsequently incubated with an anti-TH antibody (1:1000, mouse, MAB318, Merck Millipore) and horseradish peroxidase-conjugated anti-mouse IgG antibody (1:200, Vector Laboratories) for 2 h at room temperature. Staining was visualized using the V-VIP method (purple precipitate; Vector Laboratories) 17 , 52 . For immunofluorescence staining, the tissue sections were incubated with anti-TH (1:1000, mouse, MAB318, Merck Millipore), anti-RORγt (1:1000, rabbit, NLS5188, Novus Biologicals), and anti-IL-17A (1:1000, mouse, 16-7178-81, Invitrogen) antibodies at 4°C overnight. The sections were then incubated with the appropriate Alexa Fluor-conjugated anti-mouse and anti-rabbit (1:200, Invitrogen) secondary antibodies for 2 h at room temperature. Nuclei were detected by using a mounting medium containing DAPI (VECTASHIELD, H-1500) before applying the cover glass. Imaging analysis The sections were evaluated using a digital light microscope (PreciPoint M8, PreciPoint, Germany). SN segmentation was conducted based on a reference region from prior studies 17 , 53 – 55 . To enumerate neurons and T cells, the aggregate number of signals across all regions of the SN was normalized to the total area of the images (two images per animal) using the mouse click methodology in ViewPoint (PreciPoint, Germany). Outcomes were defined as the number of cells per square millimeter. Statistical analysis Statistical analyses and graphical representations were performed using GraphPad Prism version 10 for Windows (GraphPad Software, Boston, MA, USA). Outcomes were evaluated by comparison with the saline-injected group using one-way analysis of variance followed by Tukey’s multiple comparison test. Linear regression analysis was used to investigate the associations between global activity levels, cell counts, and the total cumulative dose of MPTP. Statistical significance was defined as P < 0.05. Declarations Data availability All other data supporting the findings of this study are available within the Article and its Supplementary Information. Acknowledgements This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education[RS-2024-00449397]; the STEAM Research Project funded by the NRF [RS-2024-00415347]; the Korea Research Institute of Bioscience and Biotechnology Research Initiative Program [KGM4562431]; and Electronics and Telecommunications Research Institute (ETRI) grant funded by the Korean government [Collective Brain-Behavioral Modelling in Socially Interacting Group, 24YB1200]. The funder played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript. Author information Authors and Affiliations National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Cheongju, 28116, Republic of Korea Jincheol Seo, Thanh Thi Hai Nguyen, Jinyoung Won, Chang-Yeop Jeon, Seung Ho Baek, Junghyung Park, Jung Bae Seong, Hyeon-Gu Yeo, Keonwoo Kim, Lee Wha Gwon, Minji Kim, Yu Gyeong Kim, Sang-Woo Lee, Yunkyo Jung, Jisun Min, Won Seok Choi, Jae-Won Huh, Youngjeon Lee KRIBB School of Bioscience, Korea National University of Science and Technology, Daejeon, 34113, Republic of Korea Thanh Thi Hai Nguyen, Hyeon-Gu Yeo, Lee Wha Gwon, Yu Gyeong Kim, Jae-Won Huh, Youngjeon Lee School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea Keonwoo Kim Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea Minji Kim Department of Biotechnology and Bioinformatics, Korea University, Sejong, 30019, Republic of Korea Sang-Woo Lee Department of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea Yunkyo Jung, Jisun Min Futuristic Animal Resource & Research Center, KRIBB, Cheongju, Republic of Korea Kyung Seob Lim, Author contributions J.S. conceived and designed the experiments and contributed to the writing of the original draft. T.T.H.N. performed immunohistochemistry. J.W., C.Y.J. and S.H.B. conducted model validation. J.P. and J.B.S. contributed to tissue preparation. J.M., H.Y., K.K., L.W.G., M.K., Y.G.K., S.W.L., Y.J., and W.S.C. conducted primate behavioral assessments and disease modeling. J.W.H. was responsible for project administration and funding acquisition. K.S.L. and Y.L. contributed equally to this work as corresponding authors and performed review and editing. Competing interests The authors declare no conflicts of interest. References Kalia, L. V. & Lang, A. E. Parkinson's disease. Lancet 386, 896–912 (2015). https://doi.org:10.1016/S0140-6736(14)61393-3 Braak, H., Ghebremedhin, E., Rub, U., Bratzke, H. & Del Tredici, K. Stages in the development of Parkinson's disease-related pathology. Cell Tissue Res 318, 121–134 (2004). https://doi.org:10.1007/s00441-004-0956-9 DeMaio, A., Mehrotra, S., Sambamurti, K. & Husain, S. The role of the adaptive immune system and T cell dysfunction in neurodegenerative diseases. J Neuroinflammation 19, 251 (2022). https://doi.org:10.1186/s12974-022-02605-9 He, F. & Balling, R. The role of regulatory T cells in neurodegenerative diseases. Wiley Interdiscip Rev Syst Biol Med 5, 153–180 (2013). https://doi.org:10.1002/wsbm.1187 Liblau, R. S., Gonzalez-Dunia, D., Wiendl, H. & Zipp, F. Neurons as targets for T cells in the nervous system. Trends Neurosci 36, 315–324 (2013). https://doi.org:10.1016/j.tins.2013.01.008 Dressman, D. & Elyaman, W. T Cells: A Growing Universe of Roles in Neurodegenerative Diseases. Neuroscientist 28, 335–348 (2022). https://doi.org:10.1177/10738584211024907 Korn, T. & Kallies, A. T cell responses in the central nervous system. Nat Rev Immunol 17, 179–194 (2017). https://doi.org:10.1038/nri.2016.144 Hirsch, E. C., Vyas, S. & Hunot, S. Neuroinflammation in Parkinson's disease. Parkinsonism Relat Disord 18 Suppl 1, S210–212 (2012). https://doi.org:10.1016/S1353-8020(11)70065-7 Mosley, R. L., Hutter-Saunders, J. A., Stone, D. K. & Gendelman, H. E. Inflammation and adaptive immunity in Parkinson's disease. Cold Spring Harb Perspect Med 2, a009381 (2012). https://doi.org:10.1101/cshperspect.a009381 Kannarkat, G. T., Boss, J. M. & Tansey, M. G. The role of innate and adaptive immunity in Parkinson's disease. J Parkinsons Dis 3, 493–514 (2013). https://doi.org:10.3233/JPD-130250 De Virgilio, A. et al. Parkinson's disease: Autoimmunity and neuroinflammation. Autoimmun Rev 15, 1005–1011 (2016). https://doi.org:10.1016/j.autrev.2016.07.022 Tansey, M. G. et al. Inflammation and immune dysfunction in Parkinson disease. Nat Rev Immunol 22, 657–673 (2022). https://doi.org:10.1038/s41577-022-00684-6 Chandra, G., Roy, A., Rangasamy, S. B. & Pahan, K. Induction of Adaptive Immunity Leads to Nigrostriatal Disease Progression in MPTP Mouse Model of Parkinson's Disease. J Immunol 198, 4312–4326 (2017). https://doi.org:10.4049/jimmunol.1700149 Chandra, G., Rangasamy, S. B., Roy, A., Kordower, J. H. & Pahan, K. Neutralization of RANTES and Eotaxin Prevents the Loss of Dopaminergic Neurons in a Mouse Model of Parkinson Disease. J Biol Chem 291, 15267–15281 (2016). https://doi.org:10.1074/jbc.M116.714824 Magistrelli, L. et al. Relationship between circulating CD4 + T lymphocytes and cognitive impairment in patients with Parkinson's disease. Brain Behav Immun 89, 668–674 (2020). https://doi.org:10.1016/j.bbi.2020.07.005 Brochard, V. et al. Infiltration of CD4 + lymphocytes into the brain contributes to neurodegeneration in a mouse model of Parkinson disease. J Clin Invest 119, 182–192 (2009). https://doi.org:10.1172/JCI36470 Seo, J. et al. Chronic Infiltration of T Lymphocytes into the Brain in a Non-human Primate Model of Parkinson's Disease. Neuroscience 431, 73–85 (2020). https://doi.org:10.1016/j.neuroscience.2020.01.043 Shi, Y., Wei, B., Li, L., Wang, B. & Sun, M. Th17 cells and inflammation in neurological disorders: Possible mechanisms of action. Front Immunol 13, 932152 (2022). https://doi.org:10.3389/fimmu.2022.932152 Mondal, S. et al. Low-Dose Maraviroc, an Antiretroviral Drug, Attenuates the Infiltration of T Cells into the Central Nervous System and Protects the Nigrostriatum in Hemiparkinsonian Monkeys. J Immunol (2019). https://doi.org:10.4049/jimmunol.1800587 Bolte, A. C. & Lukens, J. R. Th17 Cells in Parkinson's Disease: The Bane of the Midbrain. Cell Stem Cell 23, 5–6 (2018). https://doi.org:10.1016/j.stem.2018.06.016 Xu, Y. et al. The reciprocal interactions between microglia and T cells in Parkinson's disease: a double-edged sword. J Neuroinflammation 20, 33 (2023). https://doi.org:10.1186/s12974-023-02723-y Annunziato, F., Romagnani, C. & Romagnani, S. The 3 major types of innate and adaptive cell-mediated effector immunity. J Allergy Clin Immunol 135, 626–635 (2015). https://doi.org:10.1016/j.jaci.2014.11.001 Bettelli, E., Oukka, M. & Kuchroo, V. K. T(H)-17 cells in the circle of immunity and autoimmunity. Nat Immunol 8, 345–350 (2007). https://doi.org:10.1038/ni0407-345 Sommer, A. et al. Th17 Lymphocytes Induce Neuronal Cell Death in a Human iPSC-Based Model of Parkinson's Disease. Cell Stem Cell 23, 123–131 e126 (2018). https://doi.org:10.1016/j.stem.2018.06.015 Storelli, E., Cassina, N., Rasini, E., Marino, F. & Cosentino, M. Do Th17 Lymphocytes and IL-17 Contribute to Parkinson's Disease? A Systematic Review of Available Evidence. Front Neurol 10, 13 (2019). https://doi.org:10.3389/fneur.2019.00013 Li, J. et al. alpha-Synuclein induces Th17 differentiation and impairs the function and stability of Tregs by promoting RORC transcription in Parkinson's disease. Brain Behav Immun 108, 32–44 (2023). https://doi.org:10.1016/j.bbi.2022.10.023 Fu, J. et al. The role of Th17 cells/IL-17A in AD, PD, ALS and the strategic therapy targeting on IL-17A. J Neuroinflammation 19, 98 (2022). https://doi.org:10.1186/s12974-022-02446-6 Chen, S. et al. Increased abundance of myeloid-derived suppressor cells and Th17 cells in peripheral blood of newly-diagnosed Parkinson's disease patients. Neurosci Lett 648, 21–25 (2017). https://doi.org:10.1016/j.neulet.2017.03.045 Reynolds, A. D. et al. Regulatory T cells attenuate Th17 cell-mediated nigrostriatal dopaminergic neurodegeneration in a model of Parkinson's disease. J Immunol 184, 2261–2271 (2010). https://doi.org:10.4049/jimmunol.0901852 Li, W., Luo, Y., Xu, H., Ma, Q. & Yao, Q. Imbalance between T helper 1 and regulatory T cells plays a detrimental role in experimental Parkinson's disease in mice. J Int Med Res 49, 300060521998471 (2021). https://doi.org:10.1177/0300060521998471 Chen, Y. et al. Clinical correlation of peripheral CD4+–cell sub–sets, their imbalance and Parkinson's disease. Mol Med Rep 12, 6105–6111 (2015). https://doi.org:10.3892/mmr.2015.4136 Baird, J. K., Bourdette, D., Meshul, C. K. & Quinn, J. F. The key role of T cells in Parkinson's disease pathogenesis and therapy. Parkinsonism Relat Disord 60, 25–31 (2019). https://doi.org:10.1016/j.parkreldis.2018.10.029 Prots, I. & Winner, B. Th17 cells: a promising therapeutic target for Parkinson's disease? Expert Opin Ther Targets 23, 309–314 (2019). https://doi.org:10.1080/14728222.2019.1590336 Sommer, A. et al. Th17 Lymphocytes Induce Neuronal Cell Death in a Human iPSC-Based Model of Parkinson's Disease. Cell Stem Cell 23, 123–131 e126 (2018). https://doi.org:10.1016/j.stem.2018.06.015 Liu, Z., Huang, Y., Cao, B. B., Qiu, Y. H. & Peng, Y. P. Th17 Cells Induce Dopaminergic Neuronal Death via LFA-1/ICAM-1 Interaction in a Mouse Model of Parkinson's Disease. Mol Neurobiol 54, 7762–7776 (2017). https://doi.org:10.1007/s12035-016-0249-9 Monahan, A. J., Warren, M. & Carvey, P. M. Neuroinflammation and peripheral immune infiltration in Parkinson's disease: an autoimmune hypothesis. Cell Transplant 17, 363–372 (2008). Fang, P. et al. Immune cell subset differentiation and tissue inflammation. J Hematol Oncol 11, 97 (2018). https://doi.org:10.1186/s13045-018-0637-x MacMahon Copas, A. N., McComish, S. F., Fletcher, J. M. & Caldwell, M. A. The Pathogenesis of Parkinson's Disease: A Complex Interplay Between Astrocytes, Microglia, and T Lymphocytes? Front Neurol 12, 666737 (2021). https://doi.org:10.3389/fneur.2021.666737 Kustrimovic, N. et al. Parkinson's disease patients have a complex phenotypic and functional Th1 bias: cross-sectional studies of CD4 + Th1/Th2/T17 and Treg in drug-naive and drug-treated patients. J Neuroinflammation 15, 205 (2018). https://doi.org:10.1186/s12974-018-1248-8 Prajeeth, C. K. et al. IFN-gamma Producing Th1 Cells Induce Different Transcriptional Profiles in Microglia and Astrocytes. Front Cell Neurosci 12, 352 (2018). https://doi.org:10.3389/fncel.2018.00352 Mamuladze, T. & Kipnis, J. Type 2 immunity in the brain and brain borders. Cell Mol Immunol 20, 1290–1299 (2023). https://doi.org:10.1038/s41423-023-01043-8 Chu, Y. et al. Intrastriatal alpha-synuclein fibrils in monkeys: spreading, imaging and neuropathological changes. Brain 142, 3565–3579 (2019). https://doi.org:10.1093/brain/awz296 Seo, J. et al. A non-human primate model for stable chronic Parkinson's disease induced by MPTP administration based on individual behavioral quantification. J Neurosci Methods 311, 277–287 (2019). https://doi.org:10.1016/j.jneumeth.2018.10.037 Seo, J. et al. Impaired Hand Dexterity Function in a Non-human Primate Model with Chronic Parkinson's Disease. Exp Neurobiol 29, 376–388 (2020). https://doi.org:10.5607/en20040 Lee, Y. et al. Insulin/IGF signaling-related gene expression in the brain of a sporadic Alzheimer's disease monkey model induced by intracerebroventricular injection of streptozotocin. J Alzheimers Dis 38, 251–267 (2014). https://doi.org:10.3233/JAD-130776 Park, J. et al. Abnormal Mitochondria in a Non-human Primate Model of MPTP-induced Parkinson's Disease: Drp1 and CDK5/p25 Signaling. Exp Neurobiol 28, 414–424 (2019). https://doi.org:10.5607/en.2019.28.3.414 Yeo, H. G. et al. Characterization of Cerebral Damage in a Monkey Model of Alzheimer's Disease Induced by Intracerebroventricular Injection of Streptozotocin. J Alzheimers Dis 46, 989–1005 (2015). https://doi.org:10.3233/JAD-143222 Kilkenny, C., Browne, W. J., Cuthill, I. C., Emerson, M. & Altman, D. G. Improving bioscience research reporting: the ARRIVE guidelines for reporting animal research. PLoS Biol 8, e1000412 (2010). https://doi.org:10.1371/journal.pbio.1000412 Percie du Sert, N. et al. The ARRIVE guidelines 2.0: Updated guidelines for reporting animal research. J Cereb Blood Flow Metab 40, 1769–1777 (2020). https://doi.org:10.1177/0271678X20943823 Weatherall, D. The use of non-human primates in research. (2006). Jeong, H. S. et al. Brain structural changes in cynomolgus monkeys administered with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine: A longitudinal voxel-based morphometry and diffusion tensor imaging study. PLoS One 13, e0189804 (2018). https://doi.org:10.1371/journal.pone.0189804 Lanciego, J. L. & Gimenez-Amaya, J. M. Notes on the combined use of V-VIP and DAB peroxidase substrates for the detection of colocalising antigens. Histochem Cell Biol 111, 305–311 (1999). Lanciego, J. L. & Vazquez, A. The basal ganglia and thalamus of the long-tailed macaque in stereotaxic coordinates. A template atlas based on coronal, sagittal and horizontal brain sections. Brain Struct Funct 217, 613–666 (2012). https://doi.org:10.1007/s00429-011-0370-5 Mounayar, S. et al. A new model to study compensatory mechanisms in MPTP-treated monkeys exhibiting recovery. Brain 130, 2898–2914 (2007). https://doi.org:10.1093/brain/awm208 Ballanger, B. et al. A multi-atlas based method for automated anatomical Macaca fascicularis brain MRI segmentation and PET kinetic extraction. NeuroImage 77, 26–43 (2013). https://doi.org:10.1016/j.neuroimage.2013.03.029 Additional Declarations No competing interests reported. Supplementary Files Abstract.png Graphical Abstract SFig1.tif Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5388540","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":382052201,"identity":"d36465cc-76db-4511-b0a4-3e61e5a79c5a","order_by":0,"name":"Jincheol Seo","email":"","orcid":"","institution":"National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology","correspondingAuthor":false,"prefix":"","firstName":"Jincheol","middleName":"","lastName":"Seo","suffix":""},{"id":382052202,"identity":"7370859e-6fdf-42ca-995e-3946a08e597c","order_by":1,"name":"Thanh Thi Hai 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13:38:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5388540/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5388540/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":70012059,"identity":"19596eff-fa3b-4cd7-8337-e338a1810092","added_by":"auto","created_at":"2024-11-27 13:15:27","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1101148,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eOverview of Parkinson's disease progression through changes in behavioral signs following MPTP administration. \u003c/strong\u003e(a) Diagram illustrating the experimental sequence for MPTP administration in non-human primates. MPTP administration was discontinued after reaching the motor peak, and monkeys were sacrificed at the early (1 week; n=3, E), intermediate (3 months; n=2, M), and late (30 months; n=2, L) phases. I.M., intramuscular injection; W, weeks; M, months. (b) Changes in global activity during MPTP administration and the stabilization period for all MPTP-injected monkeys. Global activity represents changes in bradykinesia and akinesia during and after MPTP administration. Timelines were aligned such that 'Week 0' corresponds to the week in which the minimum threshold value of global activity ('motor peak') was reached for each monkey.\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/ce057e9f0fdf9781ccf061fa.png"},{"id":70010849,"identity":"681bde74-b6e0-4ecf-8354-1e3ef792ccf8","added_by":"auto","created_at":"2024-11-27 13:07:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":11967184,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTemporal changes in dopaminergic neurons and Th17 cells following MPTP administration. \u003c/strong\u003e(a) Representative staining images of tyrosine hydroxylase (TH, dopaminergic neuron marker)+ cells and RORγt+ (Th17) in the substantia nigra of monkeys at the early (1 week; n=3), intermediate (3 months; n=2), and late (30 months; n=2) phases post-MPTP administration, compared to saline-injected monkeys (n=3). Scale bars = 200 μm or 50 μm. (b-c) Temporal changes in counts of dopaminergic neurons (b) and CD4+ T cells (c) in the substantia nigra after MPTP administration, compared to saline-injected monkeys. The peak loss of dopaminergic neurons occurred in the early phase, whereas Th17 cell infiltration increased progressively over time. Data represent mean ± SEM. \u003cem\u003eP \u003c/em\u003evalues were calculated using one-way ANOVA followed by Tukey's multiple comparison test. \u003csup\u003e****\u003c/sup\u003ep \u0026lt; 0.0001; \u003csup\u003e***\u003c/sup\u003ep \u0026lt; 0.001; \u003csup\u003e**\u003c/sup\u003ep \u0026lt; 0.01; \u003csup\u003e*\u003c/sup\u003ep \u0026lt; 0.05; ns, not significant.\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/aabef6bdc026eddb952fa4ce.png"},{"id":70010856,"identity":"5e3004d8-53e8-4f3a-bb7c-2354665b53f0","added_by":"auto","created_at":"2024-11-27 13:07:28","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":9400397,"visible":true,"origin":"","legend":"\u003cp\u003eP\u003cstrong\u003ehysical proximity between Th17 cells and nigral dopaminergic neurons following MPTP injection. \u003c/strong\u003e(a) Representative images show the spatial relationship between double-labeled RORγt+ (Th17 cell marker, brown) and tyrosine hydroxylase (TH, dopaminergic neuron marker)+ cells (purple) within the substantia nigra of monkeys at the early (1 week), intermediate (3 months), and late (30 months) phases after MPTP administration. Black scale bars=20 μm. The black dashed boxes highlight areas of interest indicated by the black arrows. (b-c) Immunofluorescence-stained images represent RORγt+ (Green) co-localized with TH+ cells (Red) (b) and interleukin (IL)-17A (Red) (c), respectively, in the substantia nigra of MPTP-injected monkeys. DAPI was used to stain nuclei (Dark blue). RORγt+ cells are observed in close proximity to neighboring TH+ cells, which also exhibit larger nuclei (indicated by white arrowheads); most RORγt+ cells appear to produce IL-17A cytokine, surrounding larger nuclei (white arrows). White scale bars=20 μm.\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/da6e2498accbd2dc0d073af7.png"},{"id":70012666,"identity":"99fa3965-f11e-476e-8e21-d72963616960","added_by":"auto","created_at":"2024-11-27 13:23:28","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":15183172,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eChronic increases in infiltration of CD4+ T cells and their subsets following MPTP administration.\u003c/strong\u003e (a) Representative staining images of T-bet+ (Th1 cell marker), GATA3+ (Th2), and CD4+ cells in the substantia nigra of monkeys at early (1 week; n=3), intermediate (3 months; n=2), and late (30 months; n=2) phases after MPTP administration compared to saline-injected monkeys. Scale bars=200 μm or 50 μm. (b-d) Quantification of chronic increases in the infiltration of T-bet+ (b), GATA3+ (c), and CD4+ (d) cells in the substantia nigra. The infiltration of T-bet+, GATA3+, and CD4+ cells was significantly higher in the intermediate and late phases compared with saline-injected monkeys but showed no significant increase in the early phase. However, significant increases in T-bet+ and GATA3+ cells were observed from the early to the intermediate phase, excluding CD4+ cells. Data represent mean ± SEM. \u003cem\u003eP \u003c/em\u003evalues were calculated using one-way ANOVA followed by Tukey's multiple comparison test. \u003csup\u003e****\u003c/sup\u003ep \u0026lt; 0.0001; \u003csup\u003e***\u003c/sup\u003ep \u0026lt; 0.001; \u003csup\u003e**\u003c/sup\u003ep \u0026lt; 0.01; \u003csup\u003e*\u003c/sup\u003ep \u0026lt; 0.05; ns, not significant.\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/c6408369cb55e629cfe9ebe7.png"},{"id":70012061,"identity":"05877d41-c3e6-4bc8-a48c-f70114122df3","added_by":"auto","created_at":"2024-11-27 13:15:28","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":678785,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDynamic infiltration sequence of Th1, Th2, and Th17 cells and dopaminergic neuron reduction. \u003c/strong\u003e(a) Significant increases in RORγt+ (Th17 marker) cells were observed during the early phase (1 week; n=3), compared with both T-bet+ (Th1) and GATA3+ (Th2) cells\u003cstrong\u003e. \u003c/strong\u003e(b-c) No significant differences were observed in CD4+ T cell subsets in the intermediate (b) and late (c) phases. (d) A line graph depicting MPTP-induced PD progression shows the immediate infiltration by Th17 cells, accompanied by rapid reduction in dopaminergic neurons during the early phase. In contrast, delayed infiltration of Th1 and Th2 cells was observed during the intermediate phase. (Purple dotted line, TH+ cells; green line, T-bet+ cells, Th1; black line, GATA3+, Th2; brown line, RORγt+ cells, Th17).\u003cstrong\u003e \u003c/strong\u003eData represent mean ± SEM. \u003cem\u003eP \u003c/em\u003evalues were calculated using one-way ANOVA, followed by Tukey's multiple comparison test. \u003csup\u003e*\u003c/sup\u003ep \u0026lt; 0.05; ns, not significant.\u003c/p\u003e","description":"","filename":"Fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/dc697abb1607a0f7d7f70fe0.png"},{"id":70012060,"identity":"d4c9be32-53e2-45ec-b164-2d83e2c99d1a","added_by":"auto","created_at":"2024-11-27 13:15:28","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":607481,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCorrelation between CD4+ T cells, their subsets, and nigral dopaminergic neurons in MPTP-injected cynomolgus monkeys. \u003c/strong\u003e(a-d) Positive correlations between CD4+ T cells, their subsets, and dopaminergic neurons were identified following MPTP administration, as analyzed through linear regression with R\u003csup\u003e2\u003c/sup\u003e and P values. (a) TH+/CD4+; \u003cem\u003eR² = 0.6604, P = 0.0263\u003c/em\u003e, (b) TH+/Th1; \u003cem\u003eR² = 0.9043, P = 0.0010\u003c/em\u003e, (c) TH+/Th2; \u003cem\u003eR² = 0.8501, P = 0.0031\u003c/em\u003e, (d) TH+/Th17; \u003cem\u003eR² = 0.5965, P = 0.0418\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"Fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/9b21a6175b4d6e40fd21c4db.png"},{"id":81116378,"identity":"d3d4d4c8-455b-4b0f-b968-6815e7f66eb5","added_by":"auto","created_at":"2025-04-22 11:47:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":35722405,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/48f066ef-4cb5-4bb0-9993-a88b249c243c.pdf"},{"id":70012662,"identity":"3a339c03-8088-4dfe-bdd6-5cd6eba44458","added_by":"auto","created_at":"2024-11-27 13:23:28","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":3950597,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphical Abstract\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Abstract.png","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/a119ab84bd5680c4a58093f7.png"},{"id":70010851,"identity":"589fd70a-6a9a-4fa5-a235-0e581a1a6046","added_by":"auto","created_at":"2024-11-27 13:07:28","extension":"tif","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":247776,"visible":true,"origin":"","legend":"","description":"","filename":"SFig1.tif","url":"https://assets-eu.researchsquare.com/files/rs-5388540/v1/cd71db5d297ddcf2bfa98f64.tif"}],"financialInterests":"No competing interests reported.","formattedTitle":"Sequential infiltration of Th17 cells into the substantia nigra in a primate model of Parkinson's disease","fulltext":[{"header":"Introduction","content":"\u003cp\u003eParkinson's disease (PD) is an intractable neurodegenerative disorder characterized by progressive degeneration of dopaminergic neurons within the substantia nigra (SN) \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Recent studies have highlighted that complex interactions between the central nervous system and immunological processes are critical for the pathogenesis and progression of PD \u003csup\u003e\u003cspan additionalcitationids=\"CR4 CR5 CR6 CR7 CR8 CR9 CR10 CR11\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. A focal point in understanding the etiology of PD is the significance of immunological responses, particularly the involvement of CD4\u0026thinsp;+\u0026thinsp;T cells and their subsets \u003csup\u003e\u003cspan additionalcitationids=\"CR14 CR15 CR16 CR17 CR18\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe dysregulation of CD4\u0026thinsp;+\u0026thinsp;T cell infiltration has been a focus of recent studies because of its association with nigrostriatal dopaminergic neurodegeneration in patients with PD \u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. The CD4\u0026thinsp;+\u0026thinsp;T cell subsets that infiltrate the brain during neuroinflammation can be categorized into two groups based on their functions: pro-inflammatory, which includes T helper 1 (Th1) and T helper 17 (Th17) cells, and anti-inflammatory, which includes T helper 2 (Th2) cells. The differentiation and function of these CD4\u0026thinsp;+\u0026thinsp;T cell subsets are regulated by specific transcription factors: T-box transcription factor (T-bet) for Th1, GATA Binding Protein 3 (GATA3) for Th2, and RAR-related orphan receptor gamma t (RORγt) for Th17 \u003csup\u003e22,23\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTh17 cells, which secrete interleukin (IL)-17A and are implicated in immune-related diseases like psoriasis, rheumatoid arthritis, and inflammatory bowel disease, have been shown to directly cause neuronal cell death \u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. This highlights the correlation between Th17 cell activity and the loss of dopaminergic neurons in PD \u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. However, while the dysregulation of Th1 and Th2 cells in PD, particularly regarding peripheral neuroinflammation, has been reported \u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e, Th1 and Th2 cells are considered to have a relatively lower impact on PD pathogenesis than Th17 cells \u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e, as evidenced by PD mouse model studies \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eNonetheless, the in vivo mechanisms underlying the sequential and sustained infiltration of CD4\u0026thinsp;+\u0026thinsp;T-cell subsets, including Th17 lymphocytes, into the brain during PD progression remain unclear. It is suggested that the dysregulation of these CD4\u0026thinsp;+\u0026thinsp;T cell subsets may play a crucial role in the pathogenesis and progression of PD, potentially offering promising therapeutic targets \u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eThis study aimed to elucidate the long-term infiltration patterns of Th1, Th2, and Th17 cells in the SN during PD progression. Using a nonhuman primate (NHP) model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), we investigated the infiltration of these T cell subsets during the early, intermediate, and late stages of PD. Specifically examined were the expressions of T-bet (Th1 marker), GATA3 (Th2), RORγt (Th17), and tyrosine hydroxylase (TH, dopaminergic neurons) in the SN of the MPTP-induced NHP model.\u003c/p\u003e \u003cp\u003eHere, we aimed to divide the progression of disease phases based on the onset of PD signs following MPTP injection. Then, we analyzed the dopaminergic neuronal loss and infiltration patterns of CD4\u0026thinsp;+\u0026thinsp;T cell subsets in the SN of the MPTP-induced NHP model at each phase. This study aimed to provide insights to improve therapeutic strategies targeting subsets of CD4\u0026thinsp;+\u0026thinsp;T cells, potentially offering innovative avenues for the treatment of PD.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eAssessing progression of PD induced by MPTP injection and behavioral observation\u003c/h2\u003e \u003cp\u003eWe conducted global activity analysis using video tracking to assess behavioral changes following MPTP injections. As previously described, ten monkeys were subjected to repeated MPTP injections until their global activity levels declined to less than 10% of the pre-dose baseline (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Temporal alignment was established such that week 0 corresponded to the point at which each monkey reached the minimum threshold of global activity (motor peak). Subsequently, the monkeys maintained diminished global activity levels until sacrifice for histopathological analysis, spanning the early (1 week; n\u0026thinsp;=\u0026thinsp;3), intermediate (3 months; n\u0026thinsp;=\u0026thinsp;2), and late (30 months; n\u0026thinsp;=\u0026thinsp;2) phase, without exhibiting behavioral recovery (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). Additionally, there was no correlation found between the total cumulative dose of MPTP and the reduction in global activity (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003ea).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eTemporal changes in dopaminergic neuron loss and Th17 cell infiltration after MPTP administration\u003c/h3\u003e\n\u003cp\u003eTo investigate temporal changes in dopaminergic neuron loss and Th17 cell infiltration following MPTP administration, we conducted immunohistochemical analyses to assess levels of TH\u0026thinsp;+\u0026thinsp;and Th17 cells in the SN of saline- and MPTP-injected NHPs during the early (1 week; n\u0026thinsp;=\u0026thinsp;3), intermediate (3 months; n\u0026thinsp;=\u0026thinsp;2), and late (30 months; n\u0026thinsp;=\u0026thinsp;2) phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Dopaminergic neuron counts significantly decreased in MPTP-treated monkeys across all phases compared to controls (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). In contrast, Th17 cell infiltration showed no significant increase in the early phase but displayed a gradual and sustained increase in the SN following MPTP administration (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). Notably, the peak of dopaminergic neuron loss was observed during the early phase, while Th17 cell infiltration continued to increase progressively throughout the study period. No correlation was found between the total cumulative dose of MPTP and the decrease in dopaminergic neurons (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003eb).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003ePhysical proximity between IL-17A expressing Th17 lymphocytes and nigral dopaminergic neurons\u003c/h3\u003e\n\u003cp\u003eTo investigate the colocalization of dopaminergic neurons and Th17 cells in SN following MPTP administration, we performed immunohistochemical analyses to assess levels of TH+, RORγt+, and IL-17\u0026thinsp;+\u0026thinsp;cells in saline- and MPTP-injected NHPs (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). In the MPTP-injected group, physical proximity between Th17 lymphocytes and the reduced population of nigral dopaminergic neurons was observed. This proximity was visualized through co-localization of T lymphocytes and nigral dopaminergic neurons using DAB/VIP staining (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea) and immunofluorescence (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). Additionally, IL-17A expression in RORγt\u0026thinsp;+\u0026thinsp;cells was confirmed via immunofluorescence staining (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eDelayed infiltration of Th1 and Th2 cells into SN, unlike Th17\u003c/h3\u003e\n\u003cp\u003eTo investigate CD4\u0026thinsp;+\u0026thinsp;T cell subset infiltration across different phases post-MPTP administration, we conducted immunohistochemical analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). This analysis focused on identifying T-bet+ (Th1 cell marker), GATA3+ (Th2 cell marker), and CD4\u0026thinsp;+\u0026thinsp;cells within the SN of both saline- and MPTP- injected monkeys across the early (1 week; n\u0026thinsp;=\u0026thinsp;3), intermediate (3 months; n\u0026thinsp;=\u0026thinsp;2), and late (30 months; n\u0026thinsp;=\u0026thinsp;2) phases. This approach aimed to clarify the temporal patterns associated with PD progression, specifically focusing on CD4\u0026thinsp;+\u0026thinsp;T cell subsets.\u003c/p\u003e \u003cp\u003eThe study found significant differences in infiltration between RORγt+ (Th17) cells and T-bet+ (Th1), GATA3+ (Th2) cells during the early phase, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea. However, no significant changes were observed in the infiltration of CD4\u0026thinsp;+\u0026thinsp;T cell subsets during the intermediate (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB) or late phases (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eC). The line graph in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed, illustrating MPTP-induced PD progression shows the immediate infiltration of Th17 cells, accompanied by a rapid reduction in dopaminergic neurons during the early phase. In contrast, Th1 and Th2 cells exhibited delayed infiltration during the intermediate phase. (Purple dotted line, TH\u0026thinsp;+\u0026thinsp;cells; green line, T-bet\u0026thinsp;+\u0026thinsp;cells, Th1; black line, GATA3+, Th2; brown line, RORγt\u0026thinsp;+\u0026thinsp;cells, Th17). Additionally, no correlation was found between the total cumulative dose of MPTP and the infiltration levels of CD4+, Th1, Th2, and Th17 cells (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003eC-F).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eCorrelation between CD4 + T cells, their subsets, and nigral dopaminergic neurons in PD\u003c/h3\u003e\n\u003cp\u003ePositive correlations between CD4\u0026thinsp;+\u0026thinsp;T cells, their subsets, and dopaminergic neurons were identified following MPTP administration, as analyzed through linear regression (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e; (A) TH+/CD4+; \u003cem\u003eR\u0026sup2; = 0.6604, P\u0026thinsp;=\u0026thinsp;0.0263\u003c/em\u003e, (B) TH+/Th1; \u003cem\u003eR\u0026sup2; = 0.9043, P\u0026thinsp;=\u0026thinsp;0.0010\u003c/em\u003e, (C) TH+/Th2; \u003cem\u003eR\u0026sup2; = 0.8501, P\u0026thinsp;=\u0026thinsp;0.0031\u003c/em\u003e, (D) TH+/Th17; \u003cem\u003eR\u0026sup2; = 0.5965, P\u0026thinsp;=\u0026thinsp;0.0418\u003c/em\u003e). This analysis indicated partial recovery of dopaminergic neurons in the late phase compared to the early phase following MPTP administration, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB; however, dopaminergic neuron levels in the late phase remained significantly lower than those in the saline-injected group. This recovery coincided with increased infiltration of CD4 T cells and their subsets.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this study, we observed a distinct, sequential, and sustained infiltration pattern of CD4\u0026thinsp;+\u0026thinsp;T cell subsets in an NHP model of PD. Our findings elucidated the progression of T lymphocyte infiltration in PD, emphasizing the pivotal role of Th17 cells in the early phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). The infiltration of Th17s cell markedly differed from that Th1 and Th2 cells. Th17 cells infiltrated immediately in the early phase, unlike the delayed infiltration of Th1 and Th2 cells. Notably, the early phase infiltration of Th17 cells coincided with the rapid degeneration of dopaminergic neurons. Additionally, the close proximity between Th17 cells and the reduced number of dopaminergic neurons was observed in the SN of the MPTP-injected group (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). This observation supports the association of Th17 cells with neurodegeneration of dopaminergic neurons in PD.\u003c/p\u003e \u003cp\u003eThe association between Th17 cell infiltration and concurrent dopaminergic neuron reduction during the early phase supports previous findings on the critical role of Th17 cells in the development and progression of PD \u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. Th17 cells induced neuronal cell death and upregulated the IL-17 receptor (IL-17R) in an autologous human induced pluripotent stem cell (iPSC)-based model of PD. Although the expression of IL-17R in neuronal cells in vivo remains debated, dopaminergic neurons are known to respond to IL-17A by expressing IL-17R and activating NFκB (nuclear factor kappa-light-chain enhancer of activated B cells). Intercellular adhesion molecules (ICAM) in MPP+-treated mouse ventral mesencephalic neurons interact with lymphocyte function-associated antigen-1 (LFA1) on Th17 cells \u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. Notably, inhibiting RORγt alleviated dopaminergic neuron death in MPTP-injected mice \u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e. Therefore, targeting Th17 lymphocytes presents a promising clinical opportunity for PD treatment \u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e. However, further research is needed to comprehensively understand the role of Th17 and other cell interactions in the pathogenesis and progression of PD, given the limited scope of current animal and clinical studies \u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn the late phase, dopaminergic neurons showed a significant increase compared to the early phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). Although their count remained significantly lower than in the saline-injected group, this suggests partial recovery or long-term preservation of neurons after MPTP administration. The delayed infiltration of Th1 and Th2 cells (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec), may contribute to mechanisms supporting this recovery. This points to a complex interplay between different types of immune responses over time, impacting disease outcomes. Additionally, while this study did not fully characterize the interactions among Th1, Th2, and Th17 cells, it highlighted the sequential infiltration patterns of these subsets (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), with Th17 cells infiltrating in the early phase, contrasting with the delayed infiltration of Th1 and Th2 cells. These observations suggest potential clinical roles of CD4\u0026thinsp;+\u0026thinsp;T cell subsets in PD progression. As shown previously, specific subsets of CD4\u0026thinsp;+\u0026thinsp;T cells play peripheral regulatory roles in PD \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e,\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e,\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. Th1 and Th17 cells are associated with exacerbated PD, whereas Th2 and regulatory T (Treg) cells protect against disease progression. Th1 cells, which secrete interferon gamma (IFN-γ) as part of their pro-inflammatory role, are implicated in the exacerbation of neuroinflammation. Findings suggest that Th1 cells play an important function in PD pathogenesis \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. A previous study noted an increased proportion of Th1 cells relative to other T cell subsets in patients with PD, implying a potential Th1 bias in the peripheral system \u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. Th1 cells can enhance the phagocytosis of dopaminergic neurons by microglia during inflammation, a process that may significantly influence the pathological development of PD \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. Conversely, Th2 cells exert anti-inflammatory effects by secreting IL-4, IL-5, and IL-13 \u003csup\u003e41\u003c/sup\u003e. Th2 cells are peripherally decreased in patients with PD compared with healthy individuals, accompanied by altered anti-inflammatory responses \u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. However, similar to Th1 and Th17 cells, evidence on Th2 cells in PD is variable and contradictory, leaving this topic unresolved. This highlights the critical need for more research to comprehensively understand the role of Th2 cells in the progression of PD before making any definitive conclusions \u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis study suggests that the progression and timing of T lymphocyte infiltration, rather than the cumulative dose of MPTP exposure (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e), are more indicative of the observed changes in PD characteristics. This perspective highlights the importance of considering the sequential nature of T-cell infiltration to understand PD mechanisms more fully. The interaction between CD4\u0026thinsp;+\u0026thinsp;T lymphocytes, their subsets, and nigral dopaminergic neuron counts may be a key to understanding PD (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). This correlation implies that immune responses mediated by these T cells could influence the degeneration or recovery of dopaminergic neurons, suggesting a need for further investigation into PD pathogenesis and treatment strategies.\u003c/p\u003e \u003cp\u003eThis study has limitations due to the immediate dopaminergic neuronal damage induced during the early phase following MPTP administration. Given the gradual neuronal degeneration observed over time in human PD patients, accurately extrapolating T cell infiltration sequences using this MPTP-induced NHP model is challenging. The results of this study suggest a more complex immune interplay across different PD stages. Further studies are required to better understand the relationship between lymphocytes and PD pathogenesis. For example, NHP models that mimic progressive dopaminergic neuron loss and Lewy body pathology through alpha-synuclein overexpression, similar to that seen in human PD, could provide more relevant insights \u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn conclusion, this study reinforces the association between Th17 cells and neurodegeneration of dopaminergic neurons in the onset of PD. The findings suggest that Th17 cell infiltration may play a critical role in initiating neurodegenerative processes, underscoring the importance of immune responses in PD pathogenesis.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eExperimental animals and ethics statement\u003c/h2\u003e \u003cp\u003eTen adult female cynomolgus monkeys (\u003cem\u003eMacaca fascicularis\u003c/em\u003e), aged between 4 and 10 years and weighing between 2.8 and 3.5 kg (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), were used as described in previous studies \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e,\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e. All experimental monkeys were maintained at the National Primate Research Center (NPRC) at the Korea Research Institute of Bioscience and Biotechnology (KRIBB), as previously described \u003csup\u003e\u003cspan additionalcitationids=\"CR46\" citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e. The NHP experiments were approved by the KRIBB Institutional Animal Care and Use Committee (approval no. KRIBB-AEC-20270) and comply with the ARRIVE guidelines \u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e,\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e. To prevent potential harm from MPTP metabolites, monkeys were isolated to prevent physical contact, but were allowed visual and auditory contact with neighboring monkeys. The cage dimensions followed the guidelines of the National Institutes of Health (USA) (60 cm \u0026times; 80 cm \u0026times; 80 cm). They were provided with commercial monkey chow (Teklad 2050\u0026trade;, Envigo, USA), assorted fruits, and ad libitum water, with rubber and plastic toys for environmental enrichment. Housing conditions maintained a temperature of 24\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026ordm;C, relative humidity of 50\u0026thinsp;\u0026plusmn;\u0026thinsp;5%, and a 12-hour light/12-hour dark cycle. Veterinary monitoring adhered to NHP research guidelines \u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e,\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e. In this study, only female cynomolgus monkeys were used to minimize sex as a biological variable and limit the effect of sexual differences.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eOverview of saline and MPTP administration\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLabel\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003cp\u003e(years)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBody weight (kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDose\u003c/p\u003e \u003cp\u003e(mg/kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTotal dose\u003c/p\u003e \u003cp\u003e(mg/kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSacrifice time*\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"6\" rowspan=\"7\"\u003e \u003cp\u003eMPTP\u003c/p\u003e \u003cp\u003e(\u003cem\u003en\u0026thinsp;=\u0026thinsp;7\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eE1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"6\" rowspan=\"7\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e15.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1 W\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eE2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e15.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1 W\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eE3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1 W\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3 Mo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e7.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3 Mo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eL1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e12.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e30 Mo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eL2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e30 Mo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eSaline\u003c/p\u003e \u003cp\u003e(\u003cem\u003en\u0026thinsp;=\u0026thinsp;3\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eSaline\u003c/p\u003e \u003cp\u003e(0.6\u0026ndash;0.7 mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12 Mo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12 Mo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12 Mo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e* Sacrifice Time: Time to sacrifice post-PD symptom onset (W; Weeks, Mo; Months)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eGlobal activity\u003c/h2\u003e \u003cp\u003eThe procedures for measurement of global activity have been described in a previous study \u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. Software quantified movement changes by calculating the rate of pixel change across sequentially captured video frames, encompassing 240 min of recordings for each experimental subject. Global activity monitoring was conducted both before and after MPTP administration and was extended until the sacrifice of each subject.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eMPTP administration\u003c/h2\u003e \u003cp\u003eThe protocol for administering MPTP injections (0.2 mg/kg; Sigma-Aldrich, St. Louis, MO, USA; dissolved in saline) has been detailed in our previous studies \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. In summary, seven cynomolgus monkeys were subjected to daily intramuscular injections of MPTP into the left femoral area, whereas three monkeys received saline injections as controls. The cumulative MPTP dose was adjusted based on the behavioral evaluations of each subject (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). To evaluate the behavioral modifications resulting from the MPTP injections, global activity levels were monitored via video tracking. This procedure was continued until the global activity of the seven monkeys subjected to MPTP injection fell below 10% (denoted as the motor peak) of their baseline pre-injection levels. The overall dose of MPTP administered to each subject ranged from 4 to 15 mg/kg (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSubsequently, timelines were adjusted so that 'Week 0' matched the week in which the lowest threshold of global activity ('motor peak') was observed for each monkey. Following the motor peak, MPTP administration was terminated and each monkey was sacrificed at different phases: early (1 week; n\u0026thinsp;=\u0026thinsp;3; A1, A2, and A3), intermediate (3 months; n\u0026thinsp;=\u0026thinsp;2; S1 and S2), late (30 months; n\u0026thinsp;=\u0026thinsp;2; C4 and C5). A control group of saline-injected monkeys (n\u0026thinsp;=\u0026thinsp;3; C7, C8, and C9) was also sacrificed; notably, these three monkeys were used in a previous study \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eTissue preparation\u003c/h2\u003e \u003cp\u003eAll monkeys received transcardial perfusion with 400 mL of 100 mM phosphate-buffered saline (PBS) under profound anesthesia, which was facilitated by intramuscular injections of ketamine (1 mg/kg) at each designated time point \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. The skulls were opened to harvest the whole brain, which was immediately washed in cold PBS. Then, the brains were post-fixed in 4% paraformaldehyde and submerged in a 30% sucrose solution at 4\u0026deg;C for cryoprotection.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eImmunohistochemistry and immunofluorescence\u003c/h2\u003e \u003cp\u003eFor immunohistochemical analysis, the brains of all monkeys were coronally sectioned at 30 \u0026micro;m using a cryostat (Leica Biosystems). To block non-specific binding, free-floating sections were incubated in 4% normal horse serum (S-2000; Vector Laboratories) in PBS with 0.3% Triton X-100 for 2 h at room temperature. The sections were then incubated overnight at 4\u0026deg;C with anti-tyrosine hydroxylase (TH) (1:1000, mouse, MAB318, Merck Millipore), anti-CD4 (1:1000, mouse, 317401, Biolegend), anti-T-bet (1:1000, 14-5825-82, mouse, Invitrogen), anti-Gata-3 (1:1000, rat,14-9966-82, Invitrogen), and anti-RORγt (1:1000, rat, 14-5825-82, Invitrogen) antibodies. For secondary antibody application, the sections were incubated with the appropriate biotinylated anti-mouse IgG (1:200, BA-2000, Vector Laboratories) or anti-rat IgG (1:200, BA-9400, Vector Laboratories) antibodies for 2 h at room temperature. For staining and visualization, the ABC method (PK-6100, Vector Laboratories) was used with 3, 3\u0026rsquo;-diaminobenzidine as the peroxidase substrate (KPL DAB Reagent Set, 5510-0031, SeraCare). In double staining experiments for light microscopy, sections underwent overnight incubation at 4\u0026deg;C with the anti-RORγt antibody (1:1000, rabbit, NLS5188, Novus Biologicals) with DAB staining. The tissues were subsequently incubated with an anti-TH antibody (1:1000, mouse, MAB318, Merck Millipore) and horseradish peroxidase-conjugated anti-mouse IgG antibody (1:200, Vector Laboratories) for 2 h at room temperature. Staining was visualized using the V-VIP method (purple precipitate; Vector Laboratories) \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e. For immunofluorescence staining, the tissue sections were incubated with anti-TH (1:1000, mouse, MAB318, Merck Millipore), anti-RORγt (1:1000, rabbit, NLS5188, Novus Biologicals), and anti-IL-17A (1:1000, mouse, 16-7178-81, Invitrogen) antibodies at 4\u0026deg;C overnight. The sections were then incubated with the appropriate Alexa Fluor-conjugated anti-mouse and anti-rabbit (1:200, Invitrogen) secondary antibodies for 2 h at room temperature. Nuclei were detected by using a mounting medium containing DAPI (VECTASHIELD, H-1500) before applying the cover glass.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eImaging analysis\u003c/h2\u003e \u003cp\u003eThe sections were evaluated using a digital light microscope (PreciPoint M8, PreciPoint, Germany). SN segmentation was conducted based on a reference region from prior studies \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan additionalcitationids=\"CR54\" citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e. To enumerate neurons and T cells, the aggregate number of signals across all regions of the SN was normalized to the total area of the images (two images per animal) using the mouse click methodology in ViewPoint (PreciPoint, Germany). Outcomes were defined as the number of cells per square millimeter.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses and graphical representations were performed using GraphPad Prism version 10 for Windows (GraphPad Software, Boston, MA, USA). Outcomes were evaluated by comparison with the saline-injected group using one-way analysis of variance followed by Tukey\u0026rsquo;s multiple comparison test. Linear regression analysis was used to investigate the associations between global activity levels, cell counts, and the total cumulative dose of MPTP. Statistical significance was defined as P\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll other data supporting the findings of this study are available within the Article and its Supplementary Information.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education[RS-2024-00449397]; the STEAM Research Project funded by the NRF [RS-2024-00415347]; the Korea Research Institute of Bioscience and Biotechnology Research Initiative Program [KGM4562431]; and Electronics and Telecommunications Research Institute (ETRI) grant funded by the Korean government [Collective Brain-Behavioral Modelling in Socially Interacting Group, 24YB1200]. The funder played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthors and Affiliations\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eNational Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Cheongju, 28116, Republic of Korea\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJincheol Seo, Thanh Thi Hai Nguyen, Jinyoung Won, Chang-Yeop Jeon, Seung Ho Baek, Junghyung Park, Jung Bae Seong, Hyeon-Gu Yeo, Keonwoo Kim, Lee Wha Gwon, Minji Kim, Yu Gyeong Kim, Sang-Woo Lee, Yunkyo Jung, Jisun Min,\u0026nbsp;Won Seok Choi,\u0026nbsp;Jae-Won Huh, Youngjeon Lee\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKRIBB School of Bioscience, Korea National University of Science and Technology, Daejeon, 34113, Republic of Korea\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThanh Thi Hai Nguyen, Hyeon-Gu Yeo, Lee Wha Gwon, Yu Gyeong Kim, Jae-Won Huh, Youngjeon Lee\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSchool of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eKeonwoo Kim\u003c/p\u003e\n\u003cp\u003eDepartment of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea\u003c/p\u003e\n\u003cp\u003eMinji Kim\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDepartment of Biotechnology and Bioinformatics, Korea University, Sejong, 30019, Republic of Korea\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSang-Woo Lee\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDepartment of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYunkyo Jung, Jisun Min\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFuturistic Animal Resource \u0026amp; Research Center, KRIBB, Cheongju, Republic of Korea\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eKyung Seob Lim,\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJ.S. conceived and designed the experiments and contributed to the writing of the original draft. T.T.H.N. performed immunohistochemistry. J.W., C.Y.J. and S.H.B. conducted model validation. J.P. and J.B.S. contributed to tissue preparation. J.M., H.Y., K.K., L.W.G., M.K., Y.G.K., S.W.L., Y.J., and W.S.C. conducted primate behavioral assessments and disease modeling. J.W.H. was responsible for project administration and funding acquisition. K.S.L. and Y.L. contributed equally to this work as corresponding authors and performed review and editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflicts of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eKalia, L. V. \u0026amp; Lang, A. E. Parkinson's disease. Lancet 386, 896\u0026ndash;912 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/S0140-6736(14)61393-3\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/S0140-6736(14)61393-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBraak, H., Ghebremedhin, E., Rub, U., Bratzke, H. \u0026amp; Del Tredici, K. Stages in the development of Parkinson's disease-related pathology. Cell Tissue Res 318, 121\u0026ndash;134 (2004). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1007/s00441-004-0956-9\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1007/s00441-004-0956-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeMaio, A., Mehrotra, S., Sambamurti, K. \u0026amp; Husain, S. The role of the adaptive immune system and T cell dysfunction in neurodegenerative diseases. J Neuroinflammation 19, 251 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1186/s12974-022-02605-9\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1186/s12974-022-02605-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe, F. \u0026amp; Balling, R. The role of regulatory T cells in neurodegenerative diseases. Wiley Interdiscip Rev Syst Biol Med 5, 153\u0026ndash;180 (2013). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/wsbm.1187\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/wsbm.1187\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiblau, R. S., Gonzalez-Dunia, D., Wiendl, H. \u0026amp; Zipp, F. Neurons as targets for T cells in the nervous system. Trends Neurosci 36, 315\u0026ndash;324 (2013). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.tins.2013.01.008\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.tins.2013.01.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDressman, D. \u0026amp; Elyaman, W. T Cells: A Growing Universe of Roles in Neurodegenerative Diseases. Neuroscientist 28, 335\u0026ndash;348 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1177/10738584211024907\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1177/10738584211024907\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKorn, T. \u0026amp; Kallies, A. T cell responses in the central nervous system. Nat Rev Immunol 17, 179\u0026ndash;194 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/nri.2016.144\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/nri.2016.144\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHirsch, E. C., Vyas, S. \u0026amp; Hunot, S. Neuroinflammation in Parkinson's disease. Parkinsonism Relat Disord 18 Suppl 1, S210\u0026ndash;212 (2012). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/S1353-8020(11)70065-7\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/S1353-8020(11)70065-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMosley, R. L., Hutter-Saunders, J. A., Stone, D. K. \u0026amp; Gendelman, H. E. Inflammation and adaptive immunity in Parkinson's disease. Cold Spring Harb Perspect Med 2, a009381 (2012). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1101/cshperspect.a009381\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1101/cshperspect.a009381\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKannarkat, G. T., Boss, J. M. \u0026amp; Tansey, M. G. The role of innate and adaptive immunity in Parkinson's disease. J Parkinsons Dis 3, 493\u0026ndash;514 (2013). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3233/JPD-130250\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3233/JPD-130250\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe Virgilio, A. \u003cem\u003eet al.\u003c/em\u003e Parkinson's disease: Autoimmunity and neuroinflammation. Autoimmun Rev 15, 1005\u0026ndash;1011 (2016). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.autrev.2016.07.022\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.autrev.2016.07.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTansey, M. G. \u003cem\u003eet al.\u003c/em\u003e Inflammation and immune dysfunction in Parkinson disease. Nat Rev Immunol 22, 657\u0026ndash;673 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41577-022-00684-6\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41577-022-00684-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChandra, G., Roy, A., Rangasamy, S. B. \u0026amp; Pahan, K. Induction of Adaptive Immunity Leads to Nigrostriatal Disease Progression in MPTP Mouse Model of Parkinson's Disease. J Immunol 198, 4312\u0026ndash;4326 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.4049/jimmunol.1700149\u003c/span\u003e\u003cspan address=\"https://doi.org:10.4049/jimmunol.1700149\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChandra, G., Rangasamy, S. B., Roy, A., Kordower, J. H. \u0026amp; Pahan, K. Neutralization of RANTES and Eotaxin Prevents the Loss of Dopaminergic Neurons in a Mouse Model of Parkinson Disease. J Biol Chem 291, 15267\u0026ndash;15281 (2016). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1074/jbc.M116.714824\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1074/jbc.M116.714824\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMagistrelli, L. \u003cem\u003eet al.\u003c/em\u003e Relationship between circulating CD4\u0026thinsp;+\u0026thinsp;T lymphocytes and cognitive impairment in patients with Parkinson's disease. Brain Behav Immun 89, 668\u0026ndash;674 (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.bbi.2020.07.005\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.bbi.2020.07.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrochard, V. \u003cem\u003eet al.\u003c/em\u003e Infiltration of CD4\u0026thinsp;+\u0026thinsp;lymphocytes into the brain contributes to neurodegeneration in a mouse model of Parkinson disease. J Clin Invest 119, 182\u0026ndash;192 (2009). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1172/JCI36470\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1172/JCI36470\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeo, J. \u003cem\u003eet al.\u003c/em\u003e Chronic Infiltration of T Lymphocytes into the Brain in a Non-human Primate Model of Parkinson's Disease. Neuroscience 431, 73\u0026ndash;85 (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.neuroscience.2020.01.043\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.neuroscience.2020.01.043\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShi, Y., Wei, B., Li, L., Wang, B. \u0026amp; Sun, M. Th17 cells and inflammation in neurological disorders: Possible mechanisms of action. Front Immunol 13, 932152 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3389/fimmu.2022.932152\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3389/fimmu.2022.932152\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMondal, S. \u003cem\u003eet al.\u003c/em\u003e Low-Dose Maraviroc, an Antiretroviral Drug, Attenuates the Infiltration of T Cells into the Central Nervous System and Protects the Nigrostriatum in Hemiparkinsonian Monkeys. J Immunol (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.4049/jimmunol.1800587\u003c/span\u003e\u003cspan address=\"https://doi.org:10.4049/jimmunol.1800587\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBolte, A. C. \u0026amp; Lukens, J. R. Th17 Cells in Parkinson's Disease: The Bane of the Midbrain. Cell Stem Cell 23, 5\u0026ndash;6 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.stem.2018.06.016\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.stem.2018.06.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXu, Y. \u003cem\u003eet al.\u003c/em\u003e The reciprocal interactions between microglia and T cells in Parkinson's disease: a double-edged sword. J Neuroinflammation 20, 33 (2023). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1186/s12974-023-02723-y\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1186/s12974-023-02723-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnnunziato, F., Romagnani, C. \u0026amp; Romagnani, S. The 3 major types of innate and adaptive cell-mediated effector immunity. J Allergy Clin Immunol 135, 626\u0026ndash;635 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.jaci.2014.11.001\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.jaci.2014.11.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBettelli, E., Oukka, M. \u0026amp; Kuchroo, V. K. T(H)-17 cells in the circle of immunity and autoimmunity. Nat Immunol 8, 345\u0026ndash;350 (2007). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/ni0407-345\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/ni0407-345\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSommer, A. \u003cem\u003eet al.\u003c/em\u003e Th17 Lymphocytes Induce Neuronal Cell Death in a Human iPSC-Based Model of Parkinson's Disease. \u003cem\u003eCell Stem Cell\u003c/em\u003e 23, 123\u0026ndash;131 e126 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.stem.2018.06.015\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.stem.2018.06.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStorelli, E., Cassina, N., Rasini, E., Marino, F. \u0026amp; Cosentino, M. Do Th17 Lymphocytes and IL-17 Contribute to Parkinson's Disease? A Systematic Review of Available Evidence. Front Neurol 10, 13 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3389/fneur.2019.00013\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3389/fneur.2019.00013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi, J. \u003cem\u003eet al.\u003c/em\u003e alpha-Synuclein induces Th17 differentiation and impairs the function and stability of Tregs by promoting RORC transcription in Parkinson's disease. Brain Behav Immun 108, 32\u0026ndash;44 (2023). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.bbi.2022.10.023\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.bbi.2022.10.023\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFu, J. \u003cem\u003eet al.\u003c/em\u003e The role of Th17 cells/IL-17A in AD, PD, ALS and the strategic therapy targeting on IL-17A. J Neuroinflammation 19, 98 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1186/s12974-022-02446-6\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1186/s12974-022-02446-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen, S. \u003cem\u003eet al.\u003c/em\u003e Increased abundance of myeloid-derived suppressor cells and Th17 cells in peripheral blood of newly-diagnosed Parkinson's disease patients. Neurosci Lett 648, 21\u0026ndash;25 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.neulet.2017.03.045\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.neulet.2017.03.045\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eReynolds, A. D. \u003cem\u003eet al.\u003c/em\u003e Regulatory T cells attenuate Th17 cell-mediated nigrostriatal dopaminergic neurodegeneration in a model of Parkinson's disease. J Immunol 184, 2261\u0026ndash;2271 (2010). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.4049/jimmunol.0901852\u003c/span\u003e\u003cspan address=\"https://doi.org:10.4049/jimmunol.0901852\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi, W., Luo, Y., Xu, H., Ma, Q. \u0026amp; Yao, Q. Imbalance between T helper 1 and regulatory T cells plays a detrimental role in experimental Parkinson's disease in mice. J Int Med Res 49, 300060521998471 (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1177/0300060521998471\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1177/0300060521998471\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen, Y. \u003cem\u003eet al.\u003c/em\u003e Clinical correlation of peripheral CD4+\u0026ndash;cell sub\u0026ndash;sets, their imbalance and Parkinson's disease. Mol Med Rep 12, 6105\u0026ndash;6111 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3892/mmr.2015.4136\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3892/mmr.2015.4136\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBaird, J. K., Bourdette, D., Meshul, C. K. \u0026amp; Quinn, J. F. The key role of T cells in Parkinson's disease pathogenesis and therapy. Parkinsonism Relat Disord 60, 25\u0026ndash;31 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.parkreldis.2018.10.029\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.parkreldis.2018.10.029\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eProts, I. \u0026amp; Winner, B. Th17 cells: a promising therapeutic target for Parkinson's disease? Expert Opin Ther Targets 23, 309\u0026ndash;314 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1080/14728222.2019.1590336\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1080/14728222.2019.1590336\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSommer, A. \u003cem\u003eet al.\u003c/em\u003e Th17 Lymphocytes Induce Neuronal Cell Death in a Human iPSC-Based Model of Parkinson's Disease. \u003cem\u003eCell Stem Cell\u003c/em\u003e 23, 123\u0026ndash;131 e126 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.stem.2018.06.015\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.stem.2018.06.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu, Z., Huang, Y., Cao, B. B., Qiu, Y. H. \u0026amp; Peng, Y. P. Th17 Cells Induce Dopaminergic Neuronal Death via LFA-1/ICAM-1 Interaction in a Mouse Model of Parkinson's Disease. Mol Neurobiol 54, 7762\u0026ndash;7776 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1007/s12035-016-0249-9\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1007/s12035-016-0249-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMonahan, A. J., Warren, M. \u0026amp; Carvey, P. M. Neuroinflammation and peripheral immune infiltration in Parkinson's disease: an autoimmune hypothesis. Cell Transplant 17, 363\u0026ndash;372 (2008).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFang, P. \u003cem\u003eet al.\u003c/em\u003e Immune cell subset differentiation and tissue inflammation. J Hematol Oncol 11, 97 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1186/s13045-018-0637-x\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1186/s13045-018-0637-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMacMahon Copas, A. N., McComish, S. F., Fletcher, J. M. \u0026amp; Caldwell, M. A. The Pathogenesis of Parkinson's Disease: A Complex Interplay Between Astrocytes, Microglia, and T Lymphocytes? Front Neurol 12, 666737 (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3389/fneur.2021.666737\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3389/fneur.2021.666737\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKustrimovic, N. \u003cem\u003eet al.\u003c/em\u003e Parkinson's disease patients have a complex phenotypic and functional Th1 bias: cross-sectional studies of CD4\u0026thinsp;+\u0026thinsp;Th1/Th2/T17 and Treg in drug-naive and drug-treated patients. J Neuroinflammation 15, 205 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1186/s12974-018-1248-8\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1186/s12974-018-1248-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrajeeth, C. K. \u003cem\u003eet al.\u003c/em\u003e IFN-gamma Producing Th1 Cells Induce Different Transcriptional Profiles in Microglia and Astrocytes. Front Cell Neurosci 12, 352 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3389/fncel.2018.00352\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3389/fncel.2018.00352\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMamuladze, T. \u0026amp; Kipnis, J. Type 2 immunity in the brain and brain borders. Cell Mol Immunol 20, 1290\u0026ndash;1299 (2023). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41423-023-01043-8\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41423-023-01043-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChu, Y. \u003cem\u003eet al.\u003c/em\u003e Intrastriatal alpha-synuclein fibrils in monkeys: spreading, imaging and neuropathological changes. Brain 142, 3565\u0026ndash;3579 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1093/brain/awz296\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1093/brain/awz296\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeo, J. \u003cem\u003eet al.\u003c/em\u003e A non-human primate model for stable chronic Parkinson's disease induced by MPTP administration based on individual behavioral quantification. J Neurosci Methods 311, 277\u0026ndash;287 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.jneumeth.2018.10.037\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.jneumeth.2018.10.037\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeo, J. \u003cem\u003eet al.\u003c/em\u003e Impaired Hand Dexterity Function in a Non-human Primate Model with Chronic Parkinson's Disease. Exp Neurobiol 29, 376\u0026ndash;388 (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.5607/en20040\u003c/span\u003e\u003cspan address=\"https://doi.org:10.5607/en20040\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee, Y. \u003cem\u003eet al.\u003c/em\u003e Insulin/IGF signaling-related gene expression in the brain of a sporadic Alzheimer's disease monkey model induced by intracerebroventricular injection of streptozotocin. J Alzheimers Dis 38, 251\u0026ndash;267 (2014). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3233/JAD-130776\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3233/JAD-130776\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark, J. \u003cem\u003eet al.\u003c/em\u003e Abnormal Mitochondria in a Non-human Primate Model of MPTP-induced Parkinson's Disease: Drp1 and CDK5/p25 Signaling. Exp Neurobiol 28, 414\u0026ndash;424 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.5607/en.2019.28.3.414\u003c/span\u003e\u003cspan address=\"https://doi.org:10.5607/en.2019.28.3.414\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYeo, H. G. \u003cem\u003eet al.\u003c/em\u003e Characterization of Cerebral Damage in a Monkey Model of Alzheimer's Disease Induced by Intracerebroventricular Injection of Streptozotocin. J Alzheimers Dis 46, 989\u0026ndash;1005 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3233/JAD-143222\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3233/JAD-143222\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKilkenny, C., Browne, W. J., Cuthill, I. C., Emerson, M. \u0026amp; Altman, D. G. Improving bioscience research reporting: the ARRIVE guidelines for reporting animal research. PLoS Biol 8, e1000412 (2010). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1371/journal.pbio.1000412\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1371/journal.pbio.1000412\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePercie du Sert, N. \u003cem\u003eet al.\u003c/em\u003e The ARRIVE guidelines 2.0: Updated guidelines for reporting animal research. J Cereb Blood Flow Metab 40, 1769\u0026ndash;1777 (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1177/0271678X20943823\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1177/0271678X20943823\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWeatherall, D. The use of non-human primates in research. (2006).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJeong, H. S. \u003cem\u003eet al.\u003c/em\u003e Brain structural changes in cynomolgus monkeys administered with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine: A longitudinal voxel-based morphometry and diffusion tensor imaging study. PLoS One 13, e0189804 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1371/journal.pone.0189804\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1371/journal.pone.0189804\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLanciego, J. L. \u0026amp; Gimenez-Amaya, J. M. Notes on the combined use of V-VIP and DAB peroxidase substrates for the detection of colocalising antigens. Histochem Cell Biol 111, 305\u0026ndash;311 (1999).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLanciego, J. L. \u0026amp; Vazquez, A. The basal ganglia and thalamus of the long-tailed macaque in stereotaxic coordinates. A template atlas based on coronal, sagittal and horizontal brain sections. Brain Struct Funct 217, 613\u0026ndash;666 (2012). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1007/s00429-011-0370-5\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1007/s00429-011-0370-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMounayar, S. \u003cem\u003eet al.\u003c/em\u003e A new model to study compensatory mechanisms in MPTP-treated monkeys exhibiting recovery. Brain 130, 2898\u0026ndash;2914 (2007). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1093/brain/awm208\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1093/brain/awm208\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBallanger, B. \u003cem\u003eet al.\u003c/em\u003e A multi-atlas based method for automated anatomical Macaca fascicularis brain MRI segmentation and PET kinetic extraction. NeuroImage 77, 26\u0026ndash;43 (2013). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.neuroimage.2013.03.029\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.neuroimage.2013.03.029\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Th17 lymphocytes, Infiltration, Substantia nigra, Parkinson’s disease, Non-human primate, MPTP, Macaca fascicularis, Dopaminergic neurons","lastPublishedDoi":"10.21203/rs.3.rs-5388540/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5388540/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eParkinson’s disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra (SN). Recent studies have focused on the dysregulation of CD4+ T cell subsets, including Th17 cells, with nigrostriatal dopaminergic neurodegeneration in PD. Nonetheless, the mechanisms behind the sequential and sustained infiltration of these T cell subsets into the brain during PD progression are not well understood. This study aimed to elucidate the long-term infiltration patterns of Th1, Th2, and Th17 cells in the SN during PD progression. After injecting cynomolgus monkeys with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to develop a non-human primate model of PD, we observed dopaminergic neuronal loss and infiltration patterns of CD4+ T cell subsets in the SN at early, intermediate, and late phases. Th17 cells were observed to infiltrate immediately during the early phase, unlike the delayed infiltration observed for Th1 and Th2 cells. Notably, the early phase infiltration of Th17 cells coincides with the rapid degeneration of dopaminergic neurons. Furthermore, the physical proximity between Th17 lymphocytes and a decreased number of dopaminergic neurons was observed in the SN after MPTP injection. This study reinforces that Th17 cells are associated with neurodegeneration of dopaminergic neurons in the onset of PD.\u003c/p\u003e","manuscriptTitle":"Sequential infiltration of Th17 cells into the substantia nigra in a primate model of Parkinson's disease","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-27 13:07:22","doi":"10.21203/rs.3.rs-5388540/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"672a0683-a50a-4d03-8df5-8f9060f4dc2d","owner":[],"postedDate":"November 27th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":40684755,"name":"Biological sciences/Neuroscience/Diseases of the nervous system/Parkinsons disease"},{"id":40684756,"name":"Biological sciences/Neuroscience/Neuroimmunology"},{"id":40684757,"name":"Health sciences/Neurology/Neurological disorders/Parkinsons disease"}],"tags":[],"updatedAt":"2025-04-22T11:38:27+00:00","versionOfRecord":[],"versionCreatedAt":"2024-11-27 13:07:22","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5388540","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5388540","identity":"rs-5388540","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}