IL-1β–induced STAT3 activation drives IL-17–producing CD8⁺ tissue-resident memory T cells and exacerbates chronic psoriasis

IL-1β–induced STAT3 activation drives IL-17–producing CD8⁺ tissue-resident memory T cells and exacerbates chronic psoriasis | 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 Research Article IL-1β–induced STAT3 activation drives IL-17–producing CD8⁺ tissue-resident memory T cells and exacerbates chronic psoriasis TaeHo Kim, Chae Rim Lee, Seon-Yeong Lee, A Ram Lee, Young Joon Lee, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7432855/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 09 Dec, 2025 Read the published version in Journal of Translational Medicine → Version 1 posted 4 You are reading this latest preprint version Abstract Background The accumulation of IL-17–producing CD8 + tissue-resident memory T (TRM) cells contributes to chronic and recurrent psoriasis. Suppressor of cytokine signaling 3 (SOCS3) plays a critical role in limiting pSTAT3 and pNF-κB activity to restrain excessive IL-17–mediated inflammation. This study investigated how IL-1–induced activation of pSTAT3 and pNF-κB leads to SOCS3 downregulation in CD8 + TRM cells, facilitating the expansion of IL-17 + subsets in psoriasis. It also evaluated the therapeutic potential of restoring SOCS3 through targeted STAT3 inhibition and STAT5 activation. Methods Using both in vitro assays and an IL-1 receptor antagonist knockout mouse model of imiquimod-induced psoriasis, we examined hyperactive IL-1 signaling in CD8 + TRM cells isolated from ex vivo psoriatic samples. The STAT3 inhibitor STA-21 was used to assess its effect on SOCS3 expression and IL-17–producing TRM cell frequency. Results Hyperactivation of IL-1 signaling in chronic psoriasis established a pathogenic feedback loop in CD8⁺ TRM cells, where elevated pSTAT3 and pNF-κB activity suppressed SOCS3 expression, promoting the expansion of IL-17–producing CD8⁺ TRM cells and exacerbating disease severity. Therapeutic modulation via STA-21 restored SOCS3 levels, reduced IL-17⁺ TRM cell numbers, and disrupted this inflammatory cycle. Dual regulation of STAT3 inhibition and STAT5 activation emerged as a promising approach to attenuate psoriatic inflammation. Conclusion Our findings highlight the IL-1/pNF-κB/pSTAT3 axis in CD8⁺ TRM cells as a central driver of psoriasis pathogenesis. Restoring SOCS3 expression through combined STAT3 inhibition and STAT5 activation offers a novel immunomodulatory strategy for treating severe or recurrent psoriasis. Psoriasis STAT3 TRM17 IL-1 receptor antagonist SOCS3 Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Psoriasis is a common chronic inflammatory papulosquamous skin disease affecting more than 60 million people worldwide. It is associated with comorbidities such as psoriatic arthritis, cardiometabolic disease, and mental health disorders, all of which substantially reduce patients’ quality of life. [ 1 , 2 ] Psoriasis primarily arises from the cytokine circuit involving interleukin (IL)-23 and T helper 17 (Th17) cells, which is triggered and amplified by the innate immune system and IL-1β. [ 3 , 4 ] Previous studies have demonstrated that IL-1β is elevated in dendritic cells (DCs), macrophages, and keratinocytes within psoriatic skin lesions, contributing to the expansion of Th17 cells and IL-17–producing γδ T cells. [ 5 , 6 ] At the subcellular level, the IL-1 signaling pathway promotes Th17 cell differentiation in a signal transducer and activator of transcription (STAT)–independent manner via the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling cascade. Additionally, IL-1 enhances the Th17 pathway by suppressing suppressor of cytokine signaling 3 (SOCS3) expression, thereby promoting STAT3 activation. [ 7 ] Based on these findings, an IL-1 receptor antagonist knockout (IL-1RaKO) mouse model has been developed and widely used as an experimental model of psoriasis. [ 8 ] Skin tissue-resident memory T (TRM) cells are a subset of memory T cells that play a critical role in defending against reinvading pathogens. These cells express CD69 and CD103 and do not migrate out of the skin. [ 9 ] Transforming growth factor-β is a well-established cytokine essential for TRM cell generation, whereas IL-7 and IL-15 are critical for the localization and maintenance of these cells. [ 10 – 12 ] In psoriasis, locally produced IL-23 promotes the development of pathogenic TRM17 cells and sustains their longevity and inflammatory functions. [ 13 ] Although research investigating the influence of IL-1 on TRM cells remains limited, one study has shown that the use of IL-1β as a vaccine adjuvant significantly enhances TRM cell responses. [ 14 ] In the context of psoriasis, CD8 + TRM cells that express CCR6 and the IL-23 receptor persist in the epidermis and contribute to disease recurrence and exacerbation. [ 15 , 16 ] Consequently, TRM cells have emerged as important therapeutic targets for preventing psoriasis relapse and worsening. Psoriasis may be triggered or aggravated by infections, such as streptococcal infections, which are known to activate the IL-1 pathway. [ 1 , 17 ] However, studies specifically investigating how IL-1 affects TRM cells in psoriasis remain scarce. In this study, we used an imiquimod-induced chronic psoriasis model in IL-1RaKO mice, as this chronic model generates significantly more TRM cells than the acute model. [ 18 , 19 ] We examined the impact of IL-1 pathway enhancement on skin TRM cells. Our findings indicated that IL-1 exacerbates psoriasis by inhibiting SOCS3, leading to increased STAT3 activity and, subsequently, activation and expansion of IL-17 + CD8 + TRM cells. Furthermore, our data demonstrated that STAT3 inhibitors restore SOCS3 expression, inhibit the NF-κB pathway, and significantly reduce TRM17 cell numbers in vivo , highlighting the potential of STAT3 inhibition as a key therapeutic strategy in psoriasis treatment. Materials and methods Animals 10-week-old male BALB/c (BALB/cAnNCrlCrlj) were obtained from Orient Bio Inc. Gyeonggi-do, South Korea, and IL-1Receptor antagonist KO mouse (BALB/c background, obtained from the Pohang University of Science and Technology) were bred and housed under specific pathogen-free conditions. All experimental procedures were approved by the Institutional Animal Care and Use Committee (IACUC), Department of Laboratory Animals, College of Medicine, Catholic University of Korea, and complied with the guidelines of the National Institutes of Health. (Permit Number: 2023-0110-02) Psoriasis Induction and Treatment Administration Psoriasis was induced by 5% Imiquimod (NDC 45802-368-62, Dong-A ST, Seoul, South Korea) in 10-week-old male BALB/c, IL-1Receptor antagonist KO mouse by topical treatment on whole back skin to compare disease activity. In the case of acute psoriasis model, 62.5mg of imiquimod is applied continuously for 6 days starting the day after shaving and sacrificed on the 7th day. In the case of chronic psoriasis model, 62.5mg of imiquimod is applied for 6 consecutive days after shaving, and the recovery process is performed without any treatment for 14 days. After 14 days, 62.5mg of imiquimod is again applied for 6 consecutive days and sacrificed on the 28th day. Phosphorylated STAT3 inhibitor, STA21(SML2161-5MG.Sigma-Aldrich, Missouri, USA) was injected intraperitoneally at a concentration of 0.5 mg/kg three times a week from 7 days during the recovery period of the chronic psoriasis model until the sacrifice schedule. We conducted six psoriasis animal model experimental groups: Control (WT), Acute model of BALB/c, Chronic model of BALB/c, Acute model of IL-1RaKO, Chronic model of IL-1RaKO and STA21 with chronic IL-1RaKO psoriasis model, each group consisted of n = 5 samples and was repeated 3 times. Clinical assessment of psoriasis The clinical score of the psoriasis mouse model is measured similarly to the phenotype of an actual patient. Clinical indicators briefly consist of redness, scaling, and thickness, and each indicator is defined as a PASI score. The score range is evaluated on a scale of 0–4. As follows: 0, no psoriatic phenotype, 1, Mild red and ~ 1mm thickness on back skin, 2, Medium red and visible ridges and 1 ~ 2mm thickness and flaking along crevices occurrence on back skin, 3, Medium dark red and visible ridges are loose and > 2mm thickness and moderate flaking a large surface area on back skin, 4, Severe dark red and visible ridges are tight and severe flaking a large surface area. Psoriatic PASI scores are defined as naked measurements for each index and were measured by two independent observers. Histopathological analysis After sacrificing the acute and chronic psoriasis mouse models (Acute: 1 week; 7 days, Chronic: 4 weeks: 28 days), their skin tissues were dissected out, immediately fixed with 10% formalin for 2 days, and embedded in paraffin. Embedded skin blocks were sectioned at 5-µm thickness using a microtome (Leica Biosystems, Seoul, South Korea), and basic staining was performed with Hematoxylin (S2-5, Youngdong Pharmaceutical Co., Ltd. South Korea.) and Eosin (32002. MUTO PURE CHEMICALS CO., LTD, Tokyo, JAPAN) (H&E). The histological score was determined by taking three pictures per slide of the average area of ​​stained skin tissue, measuring the thickness of the epidermis 6 times, and averaging it to define the histological score. Phenotypic profiling of tissue-resident memory CD8 T cells (Confocal Microscopy) Skin tissue embedded in paraffin was sectioned at 5 µm. To stain specific tissue resident memory CD8 T cells in skin tissue, anti-CD8 (NBP1-49045, Novus Biologicals, Colorado, United States) and anti-CD103 (AF1990, R&D Systems, Minnesota, United States of America) were used as basic surface markers, and for each major target stain, Anti-IL-17 (ab79056, Abcam, Massachusetts, United States of America), Anti-SOCS3 (ab236519, Abcam, Massachusetts, United States of America ), and a specific CD8 TRM phenotype was confirmed by adding Anti-Phospho-NF-κB p65 (#3033S, Cell Signaling Technology, Massachusetts, United States of America) and Anti-Phospho-STAT3 Y705 (ab76315,Abcam,Massachusetts, United States of America). Nuclei were stained with 4′,6-diamidino-2-phenylindole (DAPI, D3571; Invitrogen, Carlsbad, CA, USA). Stained tissues were analyzed using a confocal microscope (LSM700 and LSM900w/AiryscanII, Carl Zeiss, Germany). Quantitative analysis of the expression pattern of each marker in skin tissue and merged cells where dermis-epidermis is connected was conducted through cell count using ZEISS ZEN Microscopy Software. Immunohistochemistry (IHC) Paraffin embedded skin tissue was sectioned at 5 um thickness, and primary monoclonal antibodies: anti-CD8 (BS-0648R, Biosciences,), anti-IL 17 (ab79056, Abcam), anti-SOCS3 (ab236519, Abcam), Anti-phospho-NF-κB p65 (#3033S, Cell Signaling Technology), Anti-Phospho-STAT3 Y705 (ab76315, Abcam),18hours (Over Night, ON) incubation was carried out. Incubating the secondary antibody against the primary antibody was performed for 30 minutes at room temperature using Dako Envision + System- HRP Labelled Polymer Anti-Rabbit (K400311-2, Agilent (Dako), California, United States of America). Afterwards, positive cells were confirmed using DAB substrate system (K346811-2, Agilent Technologies, California, United States of America). Afterwards, two pictures were taken per stained slide (400x), and quantitative analysis was performed by counting positive cells at the average position where the epidermis and dermis are connected using image J. Western blot (WB) The spleen in the psoriasis-induced mouse model (Acute, Chronic) was ground and separated into single cells, and protein lysate was prepared by diluting it in 5a0µl of RIPA Lysis and Extraction Buffer (89901, Illinois, ThermoFisher Scientific, USA). Anti- Phospho-STAT3 serine727 (#9134, Cell Signaling Technology), Anti-Phospho-STAT3 tyrosine 705 (#9131, Cell Signaling Technology), anti-STAT3(#9139, Cell Signaling Technology), Anti-phospho-NF-κB p65 (#3033S, Cell Signaling Technology), anti-NF-κB p65 (ab16502,Abcam), anti-SOCS3 (ab236519, Abcam), anti-IRAK4(4363S, Cell Signaling Technology), anti-glyceraldehyde-3-phosphate dehydrogenase, GAPDH (ab181602,Abcam) antibodies were used for quantitative analysis of protein level through Western blot. (SNAP i.d. Protein Detection System; Merck Millipore, Danvers, MA, USA). Protein concentration was quantified using bicinchoninic acid assay (23235; Illinois, ThermoFisher Scientific). Quantified protein samples were separated on 10–12% sodium dodecyl sulfate-polyacrylamide gels and ttransferred to nitrocellulose membranes (Amersham Pharmacia, Uppsala, Sweden). Primary antibodies: pSTAT3 Y705, pSTAT3 s727, STAT3, pNF-κB, NF-kB, SOCS3, IRAK4 and GAPDH were diluted in 0.4% skim milk in 1X Tris-buffered saline plus Tween-20 (TBS-T). and incubated for 35 minutes at room temperature. After the incubating, 1X TBS-T wash was performed, and horseradish peroxidase-conjugated secondary antibody was used to incubated for 20 minutes at room temperature. Band visualization for each target was carried out through image development and quantitative graph was produced with the primary target/ GAPDH after quantifying the band signal through image J. Flow cytometry (FACs) The spleens of animal models with induced acute and chronic psoriasis were ground, separated into single cells, and seeded at 1x10 6 per well. After seeding, it was incubated with PMA (P8139, Sigma-Aldrich, Germany) and Ionomycin (I0634, Sigma-Aldrich, Germany) for 4 hours. Effector CD4 T cells were stained using PC5.5-CD4 (#45-0042-82; eBioscience), FITC-IL- 17 (506910; Biolegend), and PC7-IL-4 (25-7041-82; eBioscience), and for effector CD8 T cells, PB 450-CD8 (560409; BD bioscience) and FITC-IL- 17 (506910; Biolegend), stained using PC7-IL-4 (25-7041-82; eBioscience). Additionally, in the case of tissue resident memory, staining and analysis were performed by adding APC-A700-CD103 (56-1031-82; eBioscience) and PE-CD69 (12-0691-82; eBioscience) to effector T cell conditions. Regulatory T cells were PC5.5-CD4 (#45-0042-82; eBioscience), APC-CD25 (#102012; BioLegend, San Diego, CA, USA), and PE-FOXP3 (#12-5773-82; eBioscience) was stained. Stained cells were analyzed by flow cytometry using FORTESSA (BD Biosciences, San Jose, CA, USA). In vitro evaluation of CD8 + T cell response CD8 + T cells were isolated from splenocytes of IL-1RaKO mice using CD8a (Ly-2) MicroBeads (130-117-044; Miltenyi Biotec, North Rhine-Westphalia, Germany). In vitro evaluation Splenocytes or isolated CD8 T cells from IL-1RaKO mice were cultured and stimulated for 72 h with Resiquimod (SML0196-50MG; Sigma-Aldrich; 200 ng/mL), IL-1β (401-ML; R&D Systems; 10 ng/mL), and IL-6 (406-ML-025; R&D Systems; 10 ng/mL) to induce psoriatic phenotypes via IL-1 signaling. To inhibit STAT3 hyperactivation, cells were treated with STA-21 (5 µM). After stimulation, both cells and culture supernatants were collected for transcriptional and protein expression analyses. Patient-derived specimens analysis PBMCs(n = 6) were isolated from anticoagulated whole blood samples of psoriasis patients (PASI > 15), body surface area > 1%) treated at St. Mary’s Hospital Seoul, Republic of Korea (KC17TNSI0237). Isolation was performed using Ficoll-Paque PLUS density gradient centrifugation (#17-1440-03; Cytiva, MA, USA). Freshly isolated PBMCs were subjected to immunophenotyping for characterization of disease-associated immune cell profiles. Healthy control skin samples (n = 1) and psoriatic lesion specimens (n = 9) were collected from distinct sources: the lesions were obtained from nine psoriasis patients (PASI > 10) who underwent diagnostic skin biopsies at St. Mary’s Hospital in Seoul, Republic of Korea (KC22SISI0408). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Statistical analysis Data were analyzed using Prism 8 software (GraphPad Inc., San Diego, CA, USA). Statistical significance was determined by unpaired t-test, one-way ANOVA with Kruskal-Wallis test or two-way ANOVA with Sidak's test. Results are mean ± SD. A threshold of P < 0.05 was used to determine statistical significance, indicating a 95% confidence level. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Results IL-1RaKO mice exhibited an exacerbated psoriasis phenotype To determine whether IL-1β contributes to the exacerbation of psoriasis, we established a chronic imiquimod-induced psoriasis model using IL-1RaKO mice (Fig. 1 A). Compared with chronic BALB/c psoriasis models, IL-1RaKO mice developed more severe clinical manifestations, including prominent scaling, erythema, and epidermal thickening. Although both IL-1RaKO and BALB/c mice showed increased clinical scores, including the Psoriasis Area and Severity Index (PASI), upon re-sensitization, the IL-1RaKO group demonstrated a more rapid and aggressive rise in PASI scores despite initial improvement during the recovery phase (Fig. 1 C). A similar pattern was observed in spleen enlargement, reflecting heightened systemic inflammation (Fig. 1 B). Histological analyses revealed that IL-1RaKO mice exhibited considerably more severe epidermal hyperplasia and acanthosis, along with a significant increase in Ki-67–positive proliferating cells relative to BALB/c controls (Fig. 1 D). Immunohistochemical staining further showed significantly increased numbers of CD8 + T cells, IL-17 + cells, phosphorylated NF-κB (pNF-κB)–positive cells, and phosphorylated STAT3 (pSTAT3)–positive cells in IL-1RaKO mice relative to BALB/c mice (Fig. 1 E). These findings suggested that IL-1β exacerbates chronic psoriasis by enhancing IL-17, STAT3, and NF-κB signaling pathways and promoting the accumulation of inflammatory cells. IL-1β–mediated suppression of SOCS3 facilitates IL-17 + CD103 + CD8 + T cell accumulation Flow cytometric analysis of splenocytes revealed significantly elevated populations of IL-17–producing CD4 + and CD8 + T cells in IL-1RaKO mice relative to BALB/c controls (Fig. 2 A). Given the clinical overlap between psoriasis and atopic dermatitis, we assessed IL-4–producing T cells and found significantly increased IL-4 + T cells in IL-1RaKO mice (Fig. 2 B). In contrast, the proportion of regulatory T (Treg) cells was significantly reduced in association with heightened disease activity (Fig. 2 C). To further elucidate the signaling mechanisms involved, we compared the expression of pathogenic signaling–related proteins across different disease stages and genotypes. Chronic IL-1RaKO psoriasis models exhibited significant upregulation of pNF-κB, IRAK4, and both Ser727 and Tyr705 pSTAT3 compared with BALB/c mice. Conversely, phosphorylated STAT5 and SOCS3—both known negative regulators of the STAT3 and NF-κB pathways[ 22 ,, 23 ]—were increased in BALB/c chronic psoriasis models as part of a feedback response but were greatly suppressed in IL-1RaKO models (Fig. 2 D). In both spleen and skin tissues, SOCS3 expression progressively increased with disease severity in BALB/c mice. However, in IL-1RaKO mice, SOCS3 expression remained minimal despite elevated disease activity and dense lymphocytic infiltration (Fig. 2 E-F). These results indicated that excessive IL-1β signaling suppresses SOCS3, leading to unchecked activation of the NF-κB and STAT3 pathways. IL-17 + CD103 + CD8 + T cells were expanded in the IL-1RaKO psoriasis model We next focused on the role of IL-17 + CD103 + CD8 + T cells, a subset of TRMs, in psoriasis. Flow cytometric analysis revealed a significant, disease activity–dependent increase in IL-17 + CD103 + CD8 + T cells in the chronic IL-1RaKO model compared with the BALB/c model (Fig. 3 A). Although IFN-γ + CD103 + CD8 + T cells were elevated relative to wild-type controls, their levels did not significantly differ between IL-1RaKO and BALB/c mice. These findings suggested that IL-17 expression, rather than that of IFN-γ, plays a more central role in CD8 + TRM-mediated psoriasis pathogenesis. Further analysis revealed significantly increased levels of IL-17 + CD103 + CD8 + T cells in both spleen and skin tissues of IL-1RaKO mice compared with wild-type and BALB/c mice. Additionally, pSTAT3 + CD103 + CD8 + T cells and pNF-κB + CD103 + CD8 + T cells were significantly elevated in IL-1RaKO mice, whereas SOCS3 + CD103 + CD8 + T cells were significantly decreased. (Fig. 3 B-D). These results supported the conclusion that IL-1β signaling enhances IL-17 + CD8 + TRM cell accumulation via STAT3 and NF-κB activation, while concurrently suppressing SOCS3-mediated negative regulation. STA21, a pSTAT3 inhibitor, ameliorates psoriatic inflammation by restoring SOCS3 and inhibiting IL-17–expressing TRM cells in in vitro and in vivo models pSTAT3 was selected as a therapeutic target due to its critical role as a transcription factor that induces IL-17 expression in T cells and promotes the uncontrolled proliferation of keratinocytes.[ 24 , 25 ] To determine whether direct inhibition of pSTAT3 using STA21 could restore the NF-κB/SOCS3 signaling axis and suppress IL-17 + CD8 + TRM cells, we performed in vitro experiments using splenocytes isolated from IL-1RaKO mice. Resiquimod-treated splenocytes exhibited a significant increase in both forms of pSTAT3 (S727 and Y705) of pNF-κB, along with suppression of pSTAT5 and SOCS3 expression. Upon treatment of isolated CD8 + T cells with STA21, we observed a substantial reduction in pSTAT3 (S727/Y705), of pNF-κB levels, accompanied by significant upregulation of pSTAT5 and SOCS3 (Fig. 4 A). Resiquimod stimulation also resulted in significant increases in IL-17–expressing CD4 + and CD8 + T cells. Treatment with STA21 (5 µM) significantly reduced IL-17 expression, whereas IFN-γ levels remained unchanged (Fig. 4 B). Furthermore, CD4 + CD25 + FoxP3 + regulatory T cells, which decreased under T cell activation, were restored after STA21 treatment, suggesting that the recovery is mediated via pSTAT5 activation (Fig. 4 A-C). Quantitative analysis revealed significant increases in IL-17 + CD103 + CD8 + T cells and CD4 + T cells under IL-1β stimulation, which was significantly attenuated upon STA21 treatment (Fig. 4 D). To evaluate the in vivo efficacy of STA21, we administered the compound intraperitoneally (0.5 mg/kg, three times per week) to chronic IL-1RaKO psoriasis model mice (Fig. 5 A). STA21 treatment significantly reduced clinical scores and epidermal thickness (Fig. 5 B-D); histological evaluation showed considerable reductions in acanthosis and Ki-67 + keratinocytes in STA21-treated mice (Fig. 5 D). Flow cytometry of spleen-derived immune cells revealed significant reductions in IL-4– and IL-17–expressing CD4 + and CD8 + T cells in the STA21-treated group compared with vehicle controls (Fig. 5 E). Further analysis confirmed reductions in pNF-κB and pSTAT3 levels and the restoration of pSTAT5 and SOCS3 in STA21-treated IL-1RaKO mice. Specifically, expression levels of IRAK4, pNF-κB, and both forms of pSTAT3 (S727 and Y705) were significantly decreased in the spleen, whereas SOCS3 expression was upregulated. As previously reported, [ 26 ] the recovery of SOCS3 in the absence of pSTAT3 and pNF-κB is associated with increased pSTAT5 expression, which we also observed in STA21-treated mice (Fig. 6 A). We next assessed whether STA21 treatment reduced IL-17 + CD8 + TRM cell populations in vivo . In alignment with in vitro findings, we observed significant decreases in IL-17 + CD103 + CD8 + T cells and CD4 + T cells in the STA21-treated group. However, IFN-γ + TRM cell levels remained unchanged (Fig. 6 B). Immunofluorescence analysis further confirmed significant reductions in IL-17 + , pNF-κB + , and pSTAT3 + CD8 + TRM cells in STA21-treated skin lesions and spleen compared with the vehicle group (Fig. 6 C-D). These results indicated that pSTAT3 inhibition via STA21 suppresses IL-17 + CD8 + TRM cell–mediated inflammation through modulation of the pSTAT3, pNF-κB, and SOCS3 pathways. STA21 reduces IL-17–expressing TRM cells and their precursors in peripheral blood mononuclear cells from psoriasis patients To translate our findings to human psoriasis, we examined T cell subtypes and associated inflammatory markers in lesional skin tissues and peripheral blood mononuclear cells (PBMCs) from psoriasis patients. Compared with healthy controls, patient tissues showed increased epidermal thickness and elevated numbers of CD8 + and IL-17 + T cells, which were positively correlated with disease activity. Additionally, increased expression of pSTAT3 and pNF-κB, along with reduced SOCS3 expression, was observed in a disease severity–dependent manner (Fig. 7 A). Furthermore, IL-17 + , pSTAT3 + , and pNF-κB + CD103 + CD8 + TRM cells were significantly elevated, whereas SOCS3 + CD103 + CD8 + TRM cells were considerably reduced in psoriasis patients (Fig. 7 B). To evaluate the effects of IL-1β stimulation and STA21 treatment in patient-derived PBMCs, we stimulated cells with IL-6 and IL-1β. This resulted in significant increases in IL-17 + CD4 + and CD8 + T cells, as well as elevated frequencies of CD4 + and CD8 + TRM cells and their IL-17 + subsets. STA21 treatment significantly attenuated these responses, restoring cell populations to levels observed in unstimulated controls (Fig. 7 C-D). Given the known role of CCR7 hi CD45RA low central memory T cells as precursors to TRM cells,[ 27 ] we also analyzed this population. We observed increases in central memory T cells and IL-17 + TRM precursors in the vehicle group, with significant reductions after STA21 treatment (Fig. 7 C-D). These findings suggested that STA21 effectively targets psoriasis-associated immune cell subtypes, particularly IL-17 + CD8 + TRM cells and their precursors, representing a promising therapeutic approach for psoriasis. Discussion Although IL-1β plays a pivotal role in the pathogenesis of psoriasis, the precise mechanisms by which it exacerbates disease remain incompletely understood. [ 28 ] IL-1β, produced by macrophages, dendritic cells, and keratinocytes, is a key cytokine involved in the differentiation and activation of Th17 cells. [ 29 ] Previous studies have demonstrated that the IL-1β–IL-1R signaling axis promotes the expansion of IL-17–producing γδ T cells and enhances keratinocyte-driven inflammation, thereby aggravating psoriatic lesions.[ 5 ] Mechanistically, IL-1β downregulates the expression of the negative regulator SOCS3 via activation of the NF-κB pathway, which then prolongs and intensifies STAT3 phosphorylation in response to Th17-polarizing cytokines. This shift alters the balance of STAT3 and STAT5 binding to shared consensus sequences during T cell differentiation, favoring a pro-inflammatory phenotype. [ 30 ] Although the effects of IL-1β on Th17 cells are well characterized, its impact on Tc17 or tissue-resident memory (TRM17) cells has not been fully elucidated. In this study, we demonstrate that elevated IL-1β levels in psoriasis promote hyperactivation of the IRAK4–NF-κB signaling cascade in Tc17 and TRM17 cells. This leads to a sequential downregulation of SOCS3, upregulation of STAT3, and suppression of STAT5 expression, findings consistent with previous studies in Th17 cells. [ 7 , 30 ] The SOCS family primarily functions to inhibit cytokine signaling by suppressing STAT activation through JAK–STAT receptor pathways. Among these, SOCS1 and SOCS3 have been most extensively studied due to their ability to directly bind JAKs and limit inflammatory signaling. [ 22 ] Genome-wide association studies have identified SOCS1 as a susceptibility locus in psoriasis, whereas SOCS3 polymorphisms do not appear to be associated with disease risk. [ 31 , 32 ] Functionally, SOCS3 provides a negative feedback mechanism that rapidly terminates IL-6 and IL-23 receptor signaling by inhibiting receptor-bound JAK1 and JAK2, respectively. [ 30 ] SOCS3 expression is reduced in psoriatic T cells, and conditional SOCS3 deletion in keratinocytes has been associated with exacerbated epidermal hyperplasia, CD11 + dendritic cell infiltration, and inflammation independent of T and B cells, reinforcing its potential as a biomarker and therapeutic target in psoriasis. [ 33 , 34 ] Compared with the BALB/c psoriasis group, our results showed significantly reduced SOCS3 expression and increased pSTAT3 levels in both splenic and cutaneous tissues of the IL-1RaKO group. Intriguingly, the BALB/c group exhibited an expansion of CD25 + FOXP3 + Tregs and elevated levels of both STAT5 and SOCS3. In contrast, the IL-1RaKO group exhibited increased STAT3 and decreased STAT5 expression, likely driven by enhanced IRAK4–NF-κB pathway activation. These findings suggested the presence of a functional SOCS3/STAT3 negative feedback loop in the BALB/c group, which appeared to be disrupted in the IL-1RaKO group due to elevated IL-1β. This disruption may underlie the observed imbalance in STAT signaling. Moreover, our data suggested that pSTAT3, when acting independently, may contribute to the transcriptional regulation of SOCS3 to moderate inflammatory responses. However, concurrent activation of both pNF-κB and pSTAT3 appears to suppress SOCS3 expression entirely, potentially initiating a non-specific and sustained inflammatory cascade. [ 35 ] Our results demonstrated that T cell subsets exhibiting SOCS3 downregulation in conjunction with STAT3 upregulation included both IL-17–producing CD4 + T cells and IL-17–producing CD8 + T cells. We particularly focused on the CD8 + T cell compartment because IL-17 + CD4 + T cells generally respond well to biologic therapies targeting IL-17A or IL-23; IL-17 + CD8 + T cell subsets, including TRMs, often exhibit therapeutic resistance. [ 36 ] Under conditions of elevated IL-1β, we observed substantial expansion of CD103 + CD8 + T cells, a population typically identified as TRM. Although CD69 + CD103 + expression is commonly used to define TRM, prior research has shown that CD69 hi skin-resident T17 cells exhibit minimal expression of CXCL13 and CD8A, suggesting a predominance of Th17 rather than Tc17 cells within this cluster. 37 Given that CXCL13, a chemokine associated with psoriasis severity and recurrence, is predominantly expressed by CD103 + CD8 + T cells, we operationally defined CD103 + CD8 + T cells as TRM in this study. [ 37 , 38 ] Importantly, SOCS3 downregulation, along with simultaneous upregulation of pSTAT3 and pNF-κB, was specifically observed in CD8 + TRM cells within psoriatic lesions. This dysregulated signaling was accompanied by an increased number of IL-17–producing CD8 + TRM cells. In contrast, the frequency of IFN-γ–producing TRM cells was not correlated with disease severity. Recent findings have indicated that selective depletion of TRM17 cells, while sparing IFN-γ–producing TRMs, can be achieved by modulating the ICOS–c-Maf–IL-7 signaling axis. [ 39 ] These molecular alterations promote the development and expansion of IL-17–expressing CD8 + TRM cells, a subset increasingly recognized as central to psoriasis pathogenesis. Moreover, we observed a positive correlation between IL-1β levels and the frequency of IL-4–expressing CD8 + TRM cells, suggesting a mechanistic link between psoriasis and atopic dermatitis phenotypes. We further demonstrated that selective depletion of TRM17 cells could be accomplished via STAT3 inhibition. This finding holds therapeutic relevance, as targeting residual psoriasis-specific TRM cells has emerged as a promising strategy to prevent disease recurrence. [ 33 ] Several therapeutic agents, including calcipotriol/betamethasone dipropionate, TNF-α inhibitors, IL-17 inhibitors, and IL-23 inhibitors, have been evaluated for their effects on TRM populations. [ 36 , 40 – 42 ] However, none have shown complete efficacy in eliminating TRM17 cells, and psoriasis recurrence frequently occurs after treatment discontinuation. This persistence may be driven by IL-1β–mediated SOCS3 suppression, which facilitates ongoing differentiation and maintenance of Th17 and TRM17 populations. Our findings suggest that STAT3 inhibition could serve as a novel therapeutic approach capable of overcoming this limitation. Although Miyoshi et al. [ 43 ] previously proposed the utility of the STAT3 inhibitor STA-21 in psoriasis, their investigation primarily focused on keratinocyte biology. STA-21 was able to inhibit keratinocyte proliferation by downregulating c-Myc and cyclin D1, while promoting the expression of involucrin, transglutaminase 1, and keratin 10. Topical application of 0.2% STA-21 cream for 2 weeks led to substantial clinical improvement in psoriasis patients. [ 43 ] In summary, our data showed that IL-1β promotes the expansion of Tc17 and TRM17 cells by suppressing SOCS3 expression and subsequently upregulating STAT3 via the IRAK4–NF-κB pathway. STAT3 inhibition may exert therapeutic effects in psoriasis through multiple mechanisms: attenuating Th17 and TRM17 differentiation, inhibiting IL-17–driven STAT3 signaling, reversing IL-1β–mediated SOCS3 suppression, promoting STAT5 expression, restoring SOCS3 levels, and inhibiting keratinocyte hyperproliferation. Conclusions In summary, our findings demonstrate that dysregulated IL-1β signaling in psoriasis suppresses SOCS3 which is mediated by simultaneously over activated NF-κB-STAT3 vicious cycle, disrupting the balance between pro-inflammatory and regulatory T cells and promoting the expansion of pathogenic Th17, Tc17, and TRM17 populations-particularly the CD8 + TRM17 subset that contributes to therapeutic resistance and disease recurrence. Importantly, STAT3 inhibition not only restores SOCS3 expression and regulatory T cell function by pSTAT5 upregulation but also selectively depletes TRM17 cells by cutting of NF-κB-STAT3 vicious axis and reduces keratinocyte hyperproliferation, highlighting STAT3 as a promising therapeutic target to overcome the limitations of current psoriasis treatments. Abbreviations TRM, Tissue resident memory; SOCS3, Suppressor of Cytokine Signaling 3; IL-1RaKO, Interleukin-1 Receptor Antagonist Knockout; STAT3, Signal Transducer and Activator of Transcription3 NF-κB, Nuclear factor kappa-light-chain-enhancer of activated B cells Declarations All experimental procedures were approved by the Institutional Animal Care and Use Committee (IACUC), Department of Laboratory Animals, College of Medicine, Catholic University of Korea, and complied with the guidelines of the National Institutes of Health. (Permit Number: 2023-0110-02). And all procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.(KC17TNSI0237, KC22SISI0408) Acknowledgements This research was supported by two grants from the National Research Foundation of Korea (NRF), funded by the Korea government (Ministry of Science and ICT, MSIT) under grant numbers RS-2024-00454685 and RS-2024-00347600. The funding provided by these NRF grants contributed to all stages of the research, including study design, data collection, analysis, and manuscript preparation. Author contributions K.T.H. performed the majority of the experiments, including animal studies, ex vivo flow cytometry, tissue staining (H&E, IHC, and confocal staining), and data analysis. L.C.L. was responsible for CD8 T cell isolation and in vitro experiments. L.S.Y. and L.A.R. reviewed all experimental data and ensured data integrity. L.Y.J. prepared the summary figures. B.C.H. provided blood and tissue samples from psoriasis patients, contributed to clinical discussions, and offered experimental ideas. C.M.L. conceived the overall experimental design and supervised the project. Data availability All information obtained or evaluated throughout this research is provided within this published. Original datasets can also be obtained from the corresponding author upon appropriate request. Consent for publication All authors have given their consent for the publication of this manuscript. Competing Interests All authors declare that they have no conflicts of interest to disclose References Griffiths CEM, Armstrong AW, Gudjonsson JE, Barker J. Psoriasis Lancet. 2021;397:1301–15. Bang CH, Yoon JW, Chun JH, Han JH, Park YM, Lee SJ, et al. Association of Psoriasis With Mental Health Disorders in South Korea. JAMA Dermatology. 2019;155:747–9. 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Therapeutic potential of targeting interleukin-1 family cytokines in chronic inflammatory skin diseases. Br J Dermatol. 2022;186:925–41. Basu R, Whitley SK, Bhaumik S, Zindl CL, Schoeb TR, Benveniste EN, et al. IL-1 signaling modulates activation of STAT transcription factors to antagonize retinoic acid signaling and control the TH17 cell-iTreg cell balance. Nat Immunol. 2015;16:286–95. Ozcep M, Atsu N, Solak N, Celik SK. Lack of association between SOCS3 and SOCS7 polymorphisms and psoriasis. Immun Inflamm Dis. 2022;10:e695. Tsoi LC, Spain SL, Knight J, Ellinghaus E, Stuart PE, Capon F, et al. Identification of 15 new psoriasis susceptibility loci highlights the role of innate immunity. Nat Genet. 2012;44:1341–8. Eriksen KW, Woetmann A, Skov L, Krejsgaard T, Bovin LF, Hansen ML, et al. Deficient SOCS3 and SHP-1 expression in psoriatic T cells. J Invest Dermatol. 2010;130:1590–7. Uto-Konomi A, Miyauchi K, Ozaki N, Motomura Y, Suzuki Y, Yoshimura A, et al. Dysregulation of suppressor of cytokine signaling 3 in keratinocytes causes skin inflammation mediated by interleukin-20 receptor-related cytokines. PLoS ONE. 2012;7:e40343. Dhar K, Rakesh K, Pankajakshan D, Agrawal DK. SOCS3 promotor hypermethylation and STAT3-NF-κB interaction downregulate SOCS3 expression in human coronary artery smooth muscle cells. Am J Physiol Heart Circ Physiol. 2013;304:H776–85. Mehta H, Mashiko S, Angsana J, Rubio M, Hsieh YM, Maari C, et al. Differential Changes in Inflammatory Mononuclear Phagocyte and T-Cell Profiles within Psoriatic Skin during Treatment with Guselkumab vs. Secukinumab. J Invest Dermatol. 2021;141:1707–e189. Kim SH, Oh J, Roh WS, Park J, Chung KB, Lee GH, et al. Pellino-1 promotes intrinsic activation of skin-resident IL-17A-producing T cells in psoriasis. J Allergy Clin Immunol. 2023;151:1317–28. Liu J, Chang HW, Huang ZM, Nakamura M, Sekhon S, Ahn R, et al. Single-cell RNA sequencing of psoriatic skin identifies pathogenic Tc17 cell subsets and reveals distinctions between CD8(+) T cells in autoimmunity and cancer. J Allergy Clin Immunol. 2021;147:2370–80. Park SLCS, Sells AC, Gandolfo LC, Zaid A, et al. Divergent molecular networks program functionally distinct CD8 + skin-resident memory T cells. Science. 2023;382:1073–9. Francis L, Capon F, Smith CH, Haniffa M, Mahil SK. Inflammatory memory in psoriasis: From remission to recurrence. J Allergy Clin Immunol. 2024;154:42–50. Kurihara K, Fujiyama T, Phadungsaksawasdi P, Ito T, Honda T, Tokura Y. Epidermal CD8(+)CD103(+) skin resident memory T cells in psoriasis plaques are reduced in number but remain in the basement membrane zone after topical application of corticosteroid and vitamin D3. J Dermatol Sci. 2022;105:192–4. Mashiko S, Edelmayer RM, Bi Y, Olson LM, Wetter JB, Wang J, et al. Persistence of Inflammatory Phenotype in Residual Psoriatic Plaques in Patients on Effective Biologic Therapy. J Invest Dermatol. 2020;140:1015–e254. Miyoshi K, Takaishi M, Nakajima K, Ikeda M, Kanda T, Tarutani M, et al. Stat3 as a Therapeutic Target for the Treatment of Psoriasis: A Clinical Feasibility Study with STA-21, a Stat3 Inhibitor. J Invest Dermatology. 2011;131:108–17. Supplementary Files GraphicalAbstractPDF.pdf Graphical Abstract In IL-1 receptor antagonist (IL-1Ra)-deficient mice, hyperactive IL-1 signaling drives psoriatic inflammation through dual activation of NF-κB and STAT3 pathways. This aberrant signaling cascade suppresses SOCS3 expression, a negative regulator of cytokine signaling, leading to dramatic expansion of pathogenic Th17, Tc17, and tissue-resident memory T (TRM17) cells. Pharmacological inhibition of STAT3 reverses this process by reducing phosphorylation of both STAT3 and NF-κB through restoring SOCS3 expression by STAT5 upregulation to modulate cytokine responsiveness and expanding regulatory T cells (Tregs) to counterbalance pro-inflammatory responses. This multipronged mechanism significantly alleviates epidermal hyperplasia, neutrophil infiltration, and cytokine production characteristic of psoriasis Cite Share Download PDF Status: Published Journal Publication published 09 Dec, 2025 Read the published version in Journal of Translational Medicine → Version 1 posted Reviewers agreed at journal 28 Aug, 2025 Reviewers invited by journal 28 Aug, 2025 Editor assigned by journal 25 Aug, 2025 First submitted to journal 22 Aug, 2025 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. 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09:15:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7432855/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7432855/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12967-025-07446-7","type":"published","date":"2025-12-09T15:59:35+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90585404,"identity":"8a9cd894-8d0c-4fa7-8871-a592179196d8","added_by":"auto","created_at":"2025-09-04 11:20:26","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":660778,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSevere psoriatic PASI is induced in the chronic IL-1RaKO psoriasis model.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA.\u003c/strong\u003e Schematic experimental design for chronic psoriasis induction in BALB/c and IL-1RaKO mice. \u003cstrong\u003eB.\u003c/strong\u003e Spleen weight measurement to assess immune cell hyperproliferation. \u003cstrong\u003eC.\u003c/strong\u003e Clinical scoring (redness, thickness, scaling) of dorsal skin with representative images and quantitative analysis based on PASI criteria. \u003cstrong\u003eD.\u003c/strong\u003e Representative images of epidermal hyperplasia evaluation using H\u0026amp;E staining (200×) and Ki-67 immunofluorescence (200×) for proliferation. \u003cstrong\u003eE.\u003c/strong\u003e Representative images of immunohistochemical staining (400×) of CD8, pNF-κB, pSTAT3, and IL-17 in skin sections. All values are mean ± SD. Statistical significance was determined by one-way ANOVA with Kruskal-Wallis test or two-way ANOVA with Sidak's test. *P \u0026lt; 0.05, **P \u0026lt; 0.01, ***P \u0026lt; 0.001, ****P \u0026lt; 0.0001.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/d7d61030e732b64858e6ba0b.png"},{"id":90585403,"identity":"6375b22e-b6d8-4951-9b85-922ae08a19ce","added_by":"auto","created_at":"2025-09-04 11:20:26","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":630134,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig. 2 Enhanced Th17 responses and altered STAT3 signaling in chronic IL-1RaKO psoriatic mice.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA. \u003c/strong\u003eFlow cytometry analysis of IL-17+ CD8+ (Tc17) and CD4+ (Th17) T cells in splenocytes from IL-1RaKO vs. BALB/c chronic mice. \u003cstrong\u003eB.\u003c/strong\u003e Flow cytometry quantification of IL-4+ CD4+ (Th2) and CD8+ (Tc2) T cells. \u003cstrong\u003eC.\u003c/strong\u003e Reduced Foxp3+ CD25+ CD4+ Treg frequency in IL-1RaKO mice (flow cytometry). \u003cstrong\u003eD.\u003c/strong\u003e Immunoblot of splenic lysates showing IRAK4, pNF-κB, pSTAT3 (S727/Y705) pSTAT5, and SOCS3 expression. \u003cstrong\u003eE.\u003c/strong\u003e Representative images of immunohistochemistry (400x) of SOCS3+ cells in spleen. \u003cstrong\u003eF. \u003c/strong\u003eRepresentative images of skin lesion immunohistochemistry (400x) for SOCS3+ cells. All values are mean ± SD.\u003cstrong\u003e \u003c/strong\u003eStatistical significance was determined by unpaired t-test or one-way ANOVA with Kruskal-Wallis test. *P \u0026lt; 0.05, **P \u0026lt; 0.01, ***P \u0026lt; 0.001,\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/4fba2840787edf06f8359963.png"},{"id":90585407,"identity":"f0e3e8a3-c122-45a9-9145-99af95cd80e2","added_by":"auto","created_at":"2025-09-04 11:20:26","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":766128,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRelative increase in IL-17+CD8+ TRM versus IFNγ+CD8+ TRM in chronic psoriasis induction in IL-1RaKO mice.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA. \u003c/strong\u003eFlow cytometry of splenic CD8+CD103+ TRM cells (IL-17+ and IFNγ+) in IL-1RaKO vs. BALB/c chronic mice.\u003cstrong\u003e B.\u003c/strong\u003e Representative images of immunofluorescence (200x) of splenic CD8+CD103+ TRM cells co-expressing pSTAT3, pNF-κB, or IL-17.\u003cstrong\u003eC. \u003c/strong\u003eRepresentative images of skin CD8+CD103+ TRM quantification (200x) for pSTAT3, pNF-κB, and IL-17 expression\u003cstrong\u003e. D. \u003c/strong\u003eRepresentative images of SOCS3 expression in CD8+CD103+ TRM cells (spleen/skin) via immunofluorescence (200x). All values are mean ± SD. Statistical significance was determined by one-way ANOVA with Kruskal-Wallis test. *P \u0026lt; 0.05, **P \u0026lt; 0.01, ***P \u0026lt; 0.001, ****P \u0026lt; 0.0001.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/c0e0139360f18376edbd3f8c.png"},{"id":90585406,"identity":"505b8801-21cf-42c1-a8bd-5095e89eb50a","added_by":"auto","created_at":"2025-09-04 11:20:26","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":382927,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInhibition of STAT3 signaling suppresses IL-17+ CD8 TRM cell differentiation and restores SOCS3 expression in IL-1RaKO T cells.\u003cbr\u003e\nA. \u003c/strong\u003eImmunoblot of isolated IL-1RaKO CD8+ T cells (stimulated with αCD3;2ug/ml /R848;200ng/ml /IL-6;10ng/ml /IL-1β;10ng/ml) showing STA-21 (5 µM)-mediated reduction in pSTAT3 (S727/Y705) and pNF-κB, with increased pSTAT5, SOCS3 expression \u003cstrong\u003eB. \u003c/strong\u003eFlow cytometry of IL-1RaKO splenocytes (stimulated with αCD3/R848/IL-6/IL-1β) : STA-21 decreases IL-17+ CD4+/CD8+ T cells. \u003cstrong\u003eC. \u003c/strong\u003eFlow cytometry quantification of Foxp3+CD25+ Tregs in CD4+ T cells : STA-21 increases frequency.\u003cstrong\u003e D. \u003c/strong\u003eFlow cytometry analysis of CD8+/CD4+ CD103+ TRM cells: STA-21 reduces IL-17+ TRM differentiation. All values are mean ± SD. Statistical significance was determined by one-way ANOVA with Kruskal-Wallis test. *P \u0026lt; 0.05, **P \u0026lt; 0.01, ***P \u0026lt; 0.001, ****P \u0026lt; 0.0001\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/5ff2e4b5b19707cc1ab328a9.png"},{"id":90586305,"identity":"40f65a35-6532-4c0e-82bf-af8d47741c95","added_by":"auto","created_at":"2025-09-04 11:28:25","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":478812,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eIn vivo inhibition of STAT3 signaling by STA21 ameliorates chronic psoriatic inflammation in IL-1RaKO mice.\u003cbr\u003e\nA. \u003c/strong\u003eSchematic of the experimental protocol: IL-1RaKO mice were administered IMQ to induce chronic psoriasis, with or without STA21 treatment (0.5 mg/kg, three times per week, IP, 3×/week).\u003cstrong\u003e B. \u003c/strong\u003eRepresentative dorsal skin images and clinical scores showing reduced redness, thickness, and scaling in STA21-treated mice compared to untreated IL-1RaKO chronic mice. \u003cstrong\u003eC.\u003c/strong\u003eRepresentative spleen images and quantification demonstrating decreased spleen size in STA21-treated mice. \u003cstrong\u003eD. \u003c/strong\u003eRepresentative images of H\u0026amp;E(200x) and Ki-67(Green)(200x) staining of dorsal skin sections revealing reduced epidermal thickness and proliferation (Ki-67+ cells) in STA21-treated mice. \u003cstrong\u003eE.\u003c/strong\u003e Flow cytometry analysis of IL-17+/IL-4+ CD4+ and CD8+ T cells in splenocytes from STA21-treated vs. control mice. All values are mean ± SD. Statistical significance was determined by unpaired t-test or two-way ANOVA with Sidak's test. *P \u0026lt; 0.05, **P \u0026lt; 0.01, ***P \u0026lt; 0.001, ****P \u0026lt; 0.0001.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/b0a17f4ebd9c7159265907e6.png"},{"id":90585409,"identity":"4724c399-9ca1-4068-aaca-3cb33074a19c","added_by":"auto","created_at":"2025-09-04 11:20:26","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":686806,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eIn vivo STAT3 inhibition reduces pathogenic IL-17+ CD8 TRM responses and restores SOCS3 in IL-1RaKO chronic psoriasis.\u003cbr\u003e\nA. \u003c/strong\u003eImmunoblot of splenic lysates from STA21-treated (0.5 mg/kg) IL-1RaKO chronic mice: reduced pSTAT3 (S727/Y705), pNF-κB, and increased SOCS3 expression (quantified). \u003cstrong\u003eB.\u003c/strong\u003e Flow cytometry of splenic CD4+/CD8+ CD103+ TRM cells: STA21 reduces IL-17+ TRM frequencies. \u003cstrong\u003eC.\u003c/strong\u003e Representative images of multiplex immunofluorescence (200x) of splenic CD8+CD103+ TRM cells: decreased pSTAT3/pNF-κB/IL-17 co-expression and increased SOCS3. \u003cstrong\u003eD.\u003c/strong\u003e Representative images of skin CD8+CD103+ TRM analysis (200x immunofluorescence): STA21 reduces pSTAT3/pNF-κB/IL-17 and restores SOCS3. All values are mean ± SD. Statistical significance was determined by unpaired t-test or one-way ANOVA with Kruskal-Wallis test. *P \u0026lt; 0.05, **P \u0026lt; 0.01, ***P \u0026lt; 0.001, ****P \u0026lt; 0.0001.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/0e0452534d681f38d157a58e.png"},{"id":90586306,"identity":"4e67ef83-c078-4847-bf4f-bee2f3ca49dc","added_by":"auto","created_at":"2025-09-04 11:28:26","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":639203,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePathogenic CD8+ TRM 17 expansion and SOCS3 downregulation in severe human psoriasis, and STAT3 inhibition suppresses TRM 17 responses in patient T cells.\u003cbr\u003e\nA. \u003c/strong\u003eRepresentative images of H\u0026amp;E (200x) and immunofluorescence (200x) of skin sections from healthy controls (HC), moderate-severe (PASI ≥10–11), and severe psoriasis (PASI \u0026gt;15): epidermal thickness measurement and CD8+CD103+ TRM cells co-expressing pNF-κB/pSTAT3/IL-17 (quantified). \u003cstrong\u003eB.\u003c/strong\u003e Representative images of immunohistochemistry (400x) and immunofluorescence (200x) comparing SOCS3+ cells and SOCS3 expression in CD8+CD103+ TRM cells (severe vs. moderate psoriasis; quantified). \u003cstrong\u003eC. \u003c/strong\u003eEx vivo PBMC stimulation (αCD3 2ug/ml+IL-1β 10ng/ml +IL-6 10ng/ml) ± STAT3 inhibitor (STA21, 10 µM): IL-17+ CD4+/CD8+, CCR7+CD45RA– central memory, CD69+CD103+ TRM, and IL-17+CD103+CD4/CD8 TRM frequencies (quantified) through flow cytometry. All values are mean ± SD. Statistical significance was determined by unpaired t-test or one-way ANOVA with Kruskal-Wallis test. *P \u0026lt; 0.05, **P \u0026lt; 0.01, ***P \u0026lt; 0.001, ****P \u0026lt; 0.0001\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/0291ff980f2be9a4dafa5458.png"},{"id":98244137,"identity":"dce6ffa1-7ff4-492d-b8e3-e00de5807285","added_by":"auto","created_at":"2025-12-15 16:13:17","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5498678,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/21653dc2-fc2c-44c4-b099-09a25d4344a5.pdf"},{"id":90585401,"identity":"3e472597-157f-4d1f-a4b3-a6e86194cd21","added_by":"auto","created_at":"2025-09-04 11:20:25","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":296895,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphical Abstract\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn IL-1 receptor antagonist (IL-1Ra)-deficient mice, hyperactive IL-1 signaling drives psoriatic inflammation through dual activation of NF-κB and STAT3 pathways. This aberrant signaling cascade suppresses SOCS3 expression, a negative regulator of cytokine signaling, leading to dramatic expansion of pathogenic Th17, Tc17, and tissue-resident memory T (TRM17) cells. Pharmacological inhibition of STAT3 reverses this process by reducing phosphorylation of both STAT3 and NF-κB through restoring SOCS3 expression by STAT5 upregulation to modulate cytokine responsiveness and expanding regulatory T cells (Tregs) to counterbalance pro-inflammatory responses. This multipronged mechanism significantly alleviates epidermal hyperplasia, neutrophil infiltration, and cytokine production characteristic of psoriasis\u003c/p\u003e","description":"","filename":"GraphicalAbstractPDF.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7432855/v1/eb6d7393543d6d62e4e0963b.pdf"}],"financialInterests":"","formattedTitle":"IL-1β–induced STAT3 activation drives IL-17–producing CD8⁺ tissue-resident memory T cells and exacerbates chronic psoriasis","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePsoriasis is a common chronic inflammatory papulosquamous skin disease affecting more than 60\u0026nbsp;million people worldwide. It is associated with comorbidities such as psoriatic arthritis, cardiometabolic disease, and mental health disorders, all of which substantially reduce patients\u0026rsquo; quality of life. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Psoriasis primarily arises from the cytokine circuit involving interleukin (IL)-23 and T helper 17 (Th17) cells, which is triggered and amplified by the innate immune system and IL-1β. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] Previous studies have demonstrated that IL-1β is elevated in dendritic cells (DCs), macrophages, and keratinocytes within psoriatic skin lesions, contributing to the expansion of Th17 cells and IL-17\u0026ndash;producing γδ T cells. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] At the subcellular level, the IL-1 signaling pathway promotes Th17 cell differentiation in a signal transducer and activator of transcription (STAT)\u0026ndash;independent manner via the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling cascade. Additionally, IL-1 enhances the Th17 pathway by suppressing suppressor of cytokine signaling 3 (SOCS3) expression, thereby promoting STAT3 activation. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] Based on these findings, an IL-1 receptor antagonist knockout (IL-1RaKO) mouse model has been developed and widely used as an experimental model of psoriasis. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eSkin tissue-resident memory T (TRM) cells are a subset of memory T cells that play a critical role in defending against reinvading pathogens. These cells express CD69 and CD103 and do not migrate out of the skin. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] Transforming growth factor-β is a well-established cytokine essential for TRM cell generation, whereas IL-7 and IL-15 are critical for the localization and maintenance of these cells. [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] In psoriasis, locally produced IL-23 promotes the development of pathogenic TRM17 cells and sustains their longevity and inflammatory functions. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] Although research investigating the influence of IL-1 on TRM cells remains limited, one study has shown that the use of IL-1β as a vaccine adjuvant significantly enhances TRM cell responses. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eIn the context of psoriasis, CD8\u003csup\u003e+\u003c/sup\u003e TRM cells that express CCR6 and the IL-23 receptor persist in the epidermis and contribute to disease recurrence and exacerbation. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] Consequently, TRM cells have emerged as important therapeutic targets for preventing psoriasis relapse and worsening. Psoriasis may be triggered or aggravated by infections, such as streptococcal infections, which are known to activate the IL-1 pathway. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] However, studies specifically investigating how IL-1 affects TRM cells in psoriasis remain scarce.\u003c/p\u003e\u003cp\u003eIn this study, we used an imiquimod-induced chronic psoriasis model in IL-1RaKO mice, as this chronic model generates significantly more TRM cells than the acute model. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] We examined the impact of IL-1 pathway enhancement on skin TRM cells. Our findings indicated that IL-1 exacerbates psoriasis by inhibiting SOCS3, leading to increased STAT3 activity and, subsequently, activation and expansion of IL-17\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e TRM cells. Furthermore, our data demonstrated that STAT3 inhibitors restore SOCS3 expression, inhibit the NF-κB pathway, and significantly reduce TRM17 cell numbers \u003cem\u003ein vivo\u003c/em\u003e, highlighting the potential of STAT3 inhibition as a key therapeutic strategy in psoriasis treatment.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eAnimals\u003c/h2\u003e\u003cp\u003e10-week-old male BALB/c (BALB/cAnNCrlCrlj) were obtained from Orient Bio Inc. Gyeonggi-do, South Korea, and IL-1Receptor antagonist KO mouse (BALB/c background, obtained from the Pohang University of Science and Technology) were bred and housed under specific pathogen-free conditions. All experimental procedures were approved by the Institutional Animal Care and Use Committee (IACUC), Department of Laboratory Animals, College of Medicine, Catholic University of Korea, and complied with the guidelines of the National Institutes of Health. (Permit Number: 2023-0110-02)\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003ePsoriasis Induction and Treatment Administration\u003c/h3\u003e\n\u003cp\u003ePsoriasis was induced by 5% Imiquimod (NDC 45802-368-62, Dong-A ST, Seoul, South Korea) in 10-week-old male BALB/c, IL-1Receptor antagonist KO mouse by topical treatment on whole back skin to compare disease activity. In the case of acute psoriasis model, 62.5mg of imiquimod is applied continuously for 6 days starting the day after shaving and sacrificed on the 7th day. In the case of chronic psoriasis model, 62.5mg of imiquimod is applied for 6 consecutive days after shaving, and the recovery process is performed without any treatment for 14 days. After 14 days, 62.5mg of imiquimod is again applied for 6 consecutive days and sacrificed on the 28th day. Phosphorylated STAT3 inhibitor, STA21(SML2161-5MG.Sigma-Aldrich, Missouri, USA) was injected intraperitoneally at a concentration of 0.5 mg/kg three times a week from 7 days during the recovery period of the chronic psoriasis model until the sacrifice schedule. We conducted six psoriasis animal model experimental groups: Control (WT), Acute model of BALB/c, Chronic model of BALB/c, Acute model of IL-1RaKO, Chronic model of IL-1RaKO and STA21 with chronic IL-1RaKO psoriasis model, each group consisted of n\u0026thinsp;=\u0026thinsp;5 samples and was repeated 3 times.\u003c/p\u003e\n\u003ch3\u003eClinical assessment of psoriasis\u003c/h3\u003e\n\u003cp\u003eThe clinical score of the psoriasis mouse model is measured similarly to the phenotype of an actual patient. Clinical indicators briefly consist of redness, scaling, and thickness, and each indicator is defined as a PASI score. The score range is evaluated on a scale of 0\u0026ndash;4. As follows: 0, no psoriatic phenotype, 1, Mild red and ~\u0026thinsp;1mm thickness on back skin, 2, Medium red and visible ridges and 1\u0026thinsp;~\u0026thinsp;2mm thickness and flaking along crevices occurrence on back skin, 3, Medium dark red and visible ridges are loose and \u0026gt;\u0026thinsp;2mm thickness and moderate flaking a large surface area on back skin, 4, Severe dark red and visible ridges are tight and severe flaking a large surface area. Psoriatic PASI scores are defined as naked measurements for each index and were measured by two independent observers.\u003c/p\u003e\n\u003ch3\u003eHistopathological analysis\u003c/h3\u003e\n\u003cp\u003eAfter sacrificing the acute and chronic psoriasis mouse models (Acute: 1 week; 7 days, Chronic: 4 weeks: 28 days), their skin tissues were dissected out, immediately fixed with 10% formalin for 2 days, and embedded in paraffin. Embedded skin blocks were sectioned at 5-\u0026micro;m thickness using a microtome (Leica Biosystems, Seoul, South Korea), and basic staining was performed with Hematoxylin (S2-5, Youngdong Pharmaceutical Co., Ltd. South Korea.) and Eosin (32002. MUTO PURE CHEMICALS CO., LTD, Tokyo, JAPAN) (H\u0026amp;E). The histological score was determined by taking three pictures per slide of the average area of ​​stained skin tissue, measuring the thickness of the epidermis 6 times, and averaging it to define the histological score.\u003c/p\u003e\n\u003ch3\u003ePhenotypic profiling of tissue-resident memory CD8 T cells (Confocal Microscopy)\u003c/h3\u003e\n\u003cp\u003eSkin tissue embedded in paraffin was sectioned at 5 \u0026micro;m. To stain specific tissue resident memory CD8 T cells in skin tissue, anti-CD8 (NBP1-49045, Novus Biologicals, Colorado, United States) and anti-CD103 (AF1990, R\u0026amp;D Systems, Minnesota, United States of America) were used as basic surface markers, and for each major target stain, Anti-IL-17 (ab79056, Abcam, Massachusetts, United States of America), Anti-SOCS3 (ab236519, Abcam, Massachusetts, United States of America ), and a specific CD8 TRM phenotype was confirmed by adding Anti-Phospho-NF-κB p65 (#3033S, Cell Signaling Technology, Massachusetts, United States of America) and Anti-Phospho-STAT3 Y705 (ab76315,Abcam,Massachusetts, United States of America). Nuclei were stained with 4\u0026prime;,6-diamidino-2-phenylindole (DAPI, D3571; Invitrogen, Carlsbad, CA, USA). Stained tissues were analyzed using a confocal microscope (LSM700 and LSM900w/AiryscanII, Carl Zeiss, Germany). Quantitative analysis of the expression pattern of each marker in skin tissue and merged cells where dermis-epidermis is connected was conducted through cell count using ZEISS ZEN Microscopy Software.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eImmunohistochemistry (IHC)\u003c/h2\u003e\u003cp\u003eParaffin embedded skin tissue was sectioned at 5 um thickness, and primary monoclonal antibodies: anti-CD8 (BS-0648R, Biosciences,), anti-IL 17 (ab79056, Abcam), anti-SOCS3 (ab236519, Abcam), Anti-phospho-NF-κB p65 (#3033S, Cell Signaling Technology), Anti-Phospho-STAT3 Y705 (ab76315, Abcam),18hours (Over Night, ON) incubation was carried out. Incubating the secondary antibody against the primary antibody was performed for 30 minutes at room temperature using Dako Envision\u0026thinsp;+\u0026thinsp;System- HRP Labelled Polymer Anti-Rabbit (K400311-2, Agilent (Dako), California, United States of America). Afterwards, positive cells were confirmed using DAB substrate system (K346811-2, Agilent Technologies, California, United States of America). Afterwards, two pictures were taken per stained slide (400x), and quantitative analysis was performed by counting positive cells at the average position where the epidermis and dermis are connected using image J.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eWestern blot (WB)\u003c/h3\u003e\n\u003cp\u003eThe spleen in the psoriasis-induced mouse model (Acute, Chronic) was ground and separated into single cells, and protein lysate was prepared by diluting it in 5a0\u0026micro;l of RIPA Lysis and Extraction Buffer (89901, Illinois, ThermoFisher Scientific, USA). Anti- Phospho-STAT3 serine727 (#9134, Cell Signaling Technology), Anti-Phospho-STAT3 tyrosine 705 (#9131, Cell Signaling Technology), anti-STAT3(#9139, Cell Signaling Technology), Anti-phospho-NF-κB p65 (#3033S, Cell Signaling Technology), anti-NF-κB p65 (ab16502,Abcam), anti-SOCS3 (ab236519, Abcam), anti-IRAK4(4363S, Cell Signaling Technology), anti-glyceraldehyde-3-phosphate dehydrogenase, GAPDH (ab181602,Abcam) antibodies were used for quantitative analysis of protein level through Western blot. (SNAP i.d. Protein Detection System; Merck Millipore, Danvers, MA, USA). Protein concentration was quantified using bicinchoninic acid assay (23235; Illinois, ThermoFisher Scientific). Quantified protein samples were separated on 10\u0026ndash;12% sodium dodecyl sulfate-polyacrylamide gels and ttransferred to nitrocellulose membranes (Amersham Pharmacia, Uppsala, Sweden). Primary antibodies: pSTAT3 Y705, pSTAT3 s727, STAT3, pNF-κB, NF-kB, SOCS3, IRAK4 and GAPDH were diluted in 0.4% skim milk in 1X Tris-buffered saline plus Tween-20 (TBS-T). and incubated for 35 minutes at room temperature. After the incubating, 1X TBS-T wash was performed, and horseradish peroxidase-conjugated secondary antibody was used to incubated for 20 minutes at room temperature. Band visualization for each target was carried out through image development and quantitative graph was produced with the primary target/ GAPDH after quantifying the band signal through image J.\u003c/p\u003e\n\u003ch3\u003eFlow cytometry (FACs)\u003c/h3\u003e\n\u003cp\u003eThe spleens of animal models with induced acute and chronic psoriasis were ground, separated into single cells, and seeded at 1x10\u003csup\u003e6\u003c/sup\u003e per well. After seeding, it was incubated with PMA (P8139, Sigma-Aldrich, Germany) and Ionomycin (I0634, Sigma-Aldrich, Germany) for 4 hours. Effector CD4 T cells were stained using PC5.5-CD4 (#45-0042-82; eBioscience), FITC-IL- 17 (506910; Biolegend), and PC7-IL-4 (25-7041-82; eBioscience), and for effector CD8 T cells, PB 450-CD8 (560409; BD bioscience) and FITC-IL- 17 (506910; Biolegend), stained using PC7-IL-4 (25-7041-82; eBioscience). Additionally, in the case of tissue resident memory, staining and analysis were performed by adding APC-A700-CD103 (56-1031-82; eBioscience) and PE-CD69 (12-0691-82; eBioscience) to effector T cell conditions. Regulatory T cells were PC5.5-CD4 (#45-0042-82; eBioscience), APC-CD25 (#102012; BioLegend, San Diego, CA, USA), and PE-FOXP3 (#12-5773-82; eBioscience) was stained. Stained cells were analyzed by flow cytometry using FORTESSA (BD Biosciences, San Jose, CA, USA).\u003c/p\u003e\u003cp\u003e\u003cb\u003eIn vitro\u003c/b\u003e \u003cb\u003eevaluation of CD8\u003c/b\u003e\u003csup\u003e\u003cb\u003e+\u003c/b\u003e\u003c/sup\u003e \u003cb\u003eT cell response\u003c/b\u003e\u003c/p\u003e\u003cp\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells were isolated from splenocytes of IL-1RaKO mice using CD8a (Ly-2) MicroBeads (130-117-044; Miltenyi Biotec, North Rhine-Westphalia, Germany).\u003c/p\u003e\u003cp\u003e\u003cb\u003eIn vitro\u003c/b\u003e \u003cb\u003eevaluation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eSplenocytes or isolated CD8 T cells from IL-1RaKO mice were cultured and stimulated for 72 h with Resiquimod (SML0196-50MG; Sigma-Aldrich; 200 ng/mL), IL-1β (401-ML; R\u0026amp;D Systems; 10 ng/mL), and IL-6 (406-ML-025; R\u0026amp;D Systems; 10 ng/mL) to induce psoriatic phenotypes via IL-1 signaling. To inhibit STAT3 hyperactivation, cells were treated with STA-21 (5 \u0026micro;M). After stimulation, both cells and culture supernatants were collected for transcriptional and protein expression analyses.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003ePatient-derived specimens analysis\u003c/h2\u003e\u003cp\u003ePBMCs(n\u0026thinsp;=\u0026thinsp;6) were isolated from anticoagulated whole blood samples of psoriasis patients (PASI\u0026thinsp;\u0026gt;\u0026thinsp;15), body surface area\u0026thinsp;\u0026gt;\u0026thinsp;1%) treated at St. Mary\u0026rsquo;s Hospital Seoul, Republic of Korea (KC17TNSI0237). Isolation was performed using Ficoll-Paque PLUS density gradient centrifugation (#17-1440-03; Cytiva, MA, USA). Freshly isolated PBMCs were subjected to immunophenotyping for characterization of disease-associated immune cell profiles. Healthy control skin samples (n\u0026thinsp;=\u0026thinsp;1) and psoriatic lesion specimens (n\u0026thinsp;=\u0026thinsp;9) were collected from distinct sources: the lesions were obtained from nine psoriasis patients (PASI\u0026thinsp;\u0026gt;\u0026thinsp;10) who underwent diagnostic skin biopsies at St. Mary\u0026rsquo;s Hospital in Seoul, Republic of Korea (KC22SISI0408). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eData were analyzed using Prism 8 software (GraphPad Inc., San Diego, CA, USA). Statistical significance was determined by unpaired t-test, one-way ANOVA with Kruskal-Wallis test or two-way ANOVA with Sidak's test. Results are mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD. A threshold of P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was used to determine statistical significance, indicating a 95% confidence level. *P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, **P\u0026thinsp;\u0026lt;\u0026thinsp;0.01, ***P\u0026thinsp;\u0026lt;\u0026thinsp;0.001, ****P\u0026thinsp;\u0026lt;\u0026thinsp;0.0001.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eIL-1RaKO mice exhibited an exacerbated psoriasis phenotype\u003c/h2\u003e\u003cp\u003eTo determine whether IL-1β contributes to the exacerbation of psoriasis, we established a chronic imiquimod-induced psoriasis model using IL-1RaKO mice (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). Compared with chronic BALB/c psoriasis models, IL-1RaKO mice developed more severe clinical manifestations, including prominent scaling, erythema, and epidermal thickening. Although both IL-1RaKO and BALB/c mice showed increased clinical scores, including the Psoriasis Area and Severity Index (PASI), upon re-sensitization, the IL-1RaKO group demonstrated a more rapid and aggressive rise in PASI scores despite initial improvement during the recovery phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC). A similar pattern was observed in spleen enlargement, reflecting heightened systemic inflammation (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eHistological analyses revealed that IL-1RaKO mice exhibited considerably more severe epidermal hyperplasia and acanthosis, along with a significant increase in Ki-67\u0026ndash;positive proliferating cells relative to BALB/c controls (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eD). Immunohistochemical staining further showed significantly increased numbers of CD8\u003csup\u003e+\u003c/sup\u003e T cells, IL-17\u003csup\u003e+\u003c/sup\u003e cells, phosphorylated NF-κB (pNF-κB)\u0026ndash;positive cells, and phosphorylated STAT3 (pSTAT3)\u0026ndash;positive cells in IL-1RaKO mice relative to BALB/c mice (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eE). These findings suggested that IL-1β exacerbates chronic psoriasis by enhancing IL-17, STAT3, and NF-κB signaling pathways and promoting the accumulation of inflammatory cells.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eIL-1β\u0026ndash;mediated suppression of SOCS3 facilitates IL-17\u003csup\u003e+\u003c/sup\u003e CD103\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e T cell accumulation\u003c/h2\u003e\u003cp\u003eFlow cytometric analysis of splenocytes revealed significantly elevated populations of IL-17\u0026ndash;producing CD4\u003csup\u003e+\u003c/sup\u003e and CD8\u003csup\u003e+\u003c/sup\u003e T cells in IL-1RaKO mice relative to BALB/c controls (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA). Given the clinical overlap between psoriasis and atopic dermatitis, we assessed IL-4\u0026ndash;producing T cells and found significantly increased IL-4\u003csup\u003e+\u003c/sup\u003e T cells in IL-1RaKO mice (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB). In contrast, the proportion of regulatory T (Treg) cells was significantly reduced in association with heightened disease activity (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTo further elucidate the signaling mechanisms involved, we compared the expression of pathogenic signaling\u0026ndash;related proteins across different disease stages and genotypes. Chronic IL-1RaKO psoriasis models exhibited significant upregulation of pNF-κB, IRAK4, and both Ser727 and Tyr705 pSTAT3 compared with BALB/c mice. Conversely, phosphorylated STAT5 and SOCS3\u0026mdash;both known negative regulators of the STAT3 and NF-κB pathways[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e,, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u0026mdash;were increased in BALB/c chronic psoriasis models as part of a feedback response but were greatly suppressed in IL-1RaKO models (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eD).\u003c/p\u003e\u003cp\u003eIn both spleen and skin tissues, SOCS3 expression progressively increased with disease severity in BALB/c mice. However, in IL-1RaKO mice, SOCS3 expression remained minimal despite elevated disease activity and dense lymphocytic infiltration (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eE-F). These results indicated that excessive IL-1β signaling suppresses SOCS3, leading to unchecked activation of the NF-κB and STAT3 pathways.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003eIL-17\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells were expanded in the IL-1RaKO psoriasis model\u003c/h2\u003e\u003cp\u003eWe next focused on the role of IL-17\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells, a subset of TRMs, in psoriasis. Flow cytometric analysis revealed a significant, disease activity\u0026ndash;dependent increase in IL-17\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells in the chronic IL-1RaKO model compared with the BALB/c model (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA). Although IFN-γ\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells were elevated relative to wild-type controls, their levels did not significantly differ between IL-1RaKO and BALB/c mice. These findings suggested that IL-17 expression, rather than that of IFN-γ, plays a more central role in CD8\u003csup\u003e+\u003c/sup\u003e TRM-mediated psoriasis pathogenesis.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFurther analysis revealed significantly increased levels of IL-17\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells in both spleen and skin tissues of IL-1RaKO mice compared with wild-type and BALB/c mice. Additionally, pSTAT3\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells and pNF-κB\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells were significantly elevated in IL-1RaKO mice, whereas SOCS3\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells were significantly decreased. (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB-D). These results supported the conclusion that IL-1β signaling enhances IL-17\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e TRM cell accumulation via STAT3 and NF-κB activation, while concurrently suppressing SOCS3-mediated negative regulation.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSTA21, a pSTAT3 inhibitor, ameliorates psoriatic inflammation by restoring SOCS3 and inhibiting IL-17\u0026ndash;expressing TRM cells in\u003c/b\u003e \u003cb\u003ein vitro\u003c/b\u003e \u003cb\u003eand\u003c/b\u003e \u003cb\u003ein vivo\u003c/b\u003e \u003cb\u003emodels\u003c/b\u003e\u003c/p\u003e\u003cp\u003epSTAT3 was selected as a therapeutic target due to its critical role as a transcription factor that induces IL-17 expression in T cells and promotes the uncontrolled proliferation of keratinocytes.[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] To determine whether direct inhibition of pSTAT3 using STA21 could restore the NF-κB/SOCS3 signaling axis and suppress IL-17\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e TRM cells, we performed \u003cem\u003ein vitro\u003c/em\u003e experiments using splenocytes isolated from IL-1RaKO mice. Resiquimod-treated splenocytes exhibited a significant increase in both forms of pSTAT3 (S727 and Y705) of pNF-κB, along with suppression of pSTAT5 and SOCS3 expression. Upon treatment of isolated CD8\u003csup\u003e+\u003c/sup\u003e T cells with STA21, we observed a substantial reduction in pSTAT3 (S727/Y705), of pNF-κB levels, accompanied by significant upregulation of pSTAT5 and SOCS3 (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eResiquimod stimulation also resulted in significant increases in IL-17\u0026ndash;expressing CD4\u003csup\u003e+\u003c/sup\u003e and CD8\u003csup\u003e+\u003c/sup\u003e T cells. Treatment with STA21 (5 \u0026micro;M) significantly reduced IL-17 expression, whereas IFN-γ levels remained unchanged (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB). Furthermore, CD4\u003csup\u003e+\u003c/sup\u003eCD25\u003csup\u003e+\u003c/sup\u003eFoxP3\u003csup\u003e+\u003c/sup\u003e regulatory T cells, which decreased under T cell activation, were restored after STA21 treatment, suggesting that the recovery is mediated via pSTAT5 activation (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA-C). Quantitative analysis revealed significant increases in IL-17\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells and CD4\u003csup\u003e+\u003c/sup\u003e T cells under IL-1β stimulation, which was significantly attenuated upon STA21 treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eD).\u003c/p\u003e\u003cp\u003eTo evaluate the \u003cem\u003ein vivo\u003c/em\u003e efficacy of STA21, we administered the compound intraperitoneally (0.5 mg/kg, three times per week) to chronic IL-1RaKO psoriasis model mice (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA). STA21 treatment significantly reduced clinical scores and epidermal thickness (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB-D); histological evaluation showed considerable reductions in acanthosis and Ki-67\u003csup\u003e+\u003c/sup\u003e keratinocytes in STA21-treated mice (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eD). Flow cytometry of spleen-derived immune cells revealed significant reductions in IL-4\u0026ndash; and IL-17\u0026ndash;expressing CD4\u003csup\u003e+\u003c/sup\u003e and CD8\u003csup\u003e+\u003c/sup\u003e T cells in the STA21-treated group compared with vehicle controls (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eE).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFurther analysis confirmed reductions in pNF-κB and pSTAT3 levels and the restoration of pSTAT5 and SOCS3 in STA21-treated IL-1RaKO mice. Specifically, expression levels of IRAK4, pNF-κB, and both forms of pSTAT3 (S727 and Y705) were significantly decreased in the spleen, whereas SOCS3 expression was upregulated. As previously reported, [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] the recovery of SOCS3 in the absence of pSTAT3 and pNF-κB is associated with increased pSTAT5 expression, which we also observed in STA21-treated mice (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eWe next assessed whether STA21 treatment reduced IL-17\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e TRM cell populations \u003cem\u003ein vivo\u003c/em\u003e. In alignment with \u003cem\u003ein vitro\u003c/em\u003e findings, we observed significant decreases in IL-17\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e T cells and CD4\u003csup\u003e+\u003c/sup\u003e T cells in the STA21-treated group. However, IFN-γ\u003csup\u003e+\u003c/sup\u003e TRM cell levels remained unchanged (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB). Immunofluorescence analysis further confirmed significant reductions in IL-17\u003csup\u003e+\u003c/sup\u003e, pNF-κB\u003csup\u003e+\u003c/sup\u003e, and pSTAT3\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e TRM cells in STA21-treated skin lesions and spleen compared with the vehicle group (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eC-D). These results indicated that pSTAT3 inhibition via STA21 suppresses IL-17\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e TRM cell\u0026ndash;mediated inflammation through modulation of the pSTAT3, pNF-κB, and SOCS3 pathways.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSTA21 reduces IL-17\u0026ndash;expressing TRM cells and their precursors in peripheral blood mononuclear cells from psoriasis patients\u003c/b\u003e\u003c/p\u003e\u003cp\u003eTo translate our findings to human psoriasis, we examined T cell subtypes and associated inflammatory markers in lesional skin tissues and peripheral blood mononuclear cells (PBMCs) from psoriasis patients. Compared with healthy controls, patient tissues showed increased epidermal thickness and elevated numbers of CD8\u003csup\u003e+\u003c/sup\u003e and IL-17\u003csup\u003e+\u003c/sup\u003e T cells, which were positively correlated with disease activity. Additionally, increased expression of pSTAT3 and pNF-κB, along with reduced SOCS3 expression, was observed in a disease severity\u0026ndash;dependent manner (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eA). Furthermore, IL-17\u003csup\u003e+\u003c/sup\u003e, pSTAT3\u003csup\u003e+\u003c/sup\u003e, and pNF-κB\u003csup\u003e+\u003c/sup\u003e CD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e TRM cells were significantly elevated, whereas SOCS3\u003csup\u003e+\u003c/sup\u003e CD103\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003e TRM cells were considerably reduced in psoriasis patients (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eB).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTo evaluate the effects of IL-1β stimulation and STA21 treatment in patient-derived PBMCs, we stimulated cells with IL-6 and IL-1β. This resulted in significant increases in IL-17\u003csup\u003e+\u003c/sup\u003e CD4\u003csup\u003e+\u003c/sup\u003e and CD8\u003csup\u003e+\u003c/sup\u003e T cells, as well as elevated frequencies of CD4\u003csup\u003e+\u003c/sup\u003e and CD8\u003csup\u003e+\u003c/sup\u003e TRM cells and their IL-17\u003csup\u003e+\u003c/sup\u003e subsets. STA21 treatment significantly attenuated these responses, restoring cell populations to levels observed in unstimulated controls (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eC-D).\u003c/p\u003e\u003cp\u003eGiven the known role of CCR7\u003csup\u003ehi\u003c/sup\u003eCD45RA\u003csup\u003elow\u003c/sup\u003e central memory T cells as precursors to TRM cells,[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] we also analyzed this population. We observed increases in central memory T cells and IL-17\u003csup\u003e+\u003c/sup\u003e TRM precursors in the vehicle group, with significant reductions after STA21 treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eC-D). These findings suggested that STA21 effectively targets psoriasis-associated immune cell subtypes, particularly IL-17\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e TRM cells and their precursors, representing a promising therapeutic approach for psoriasis.\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eAlthough IL-1β plays a pivotal role in the pathogenesis of psoriasis, the precise mechanisms by which it exacerbates disease remain incompletely understood. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] IL-1β, produced by macrophages, dendritic cells, and keratinocytes, is a key cytokine involved in the differentiation and activation of Th17 cells. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] Previous studies have demonstrated that the IL-1β\u0026ndash;IL-1R signaling axis promotes the expansion of IL-17\u0026ndash;producing γδ T cells and enhances keratinocyte-driven inflammation, thereby aggravating psoriatic lesions.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] Mechanistically, IL-1β downregulates the expression of the negative regulator SOCS3 via activation of the NF-κB pathway, which then prolongs and intensifies STAT3 phosphorylation in response to Th17-polarizing cytokines. This shift alters the balance of STAT3 and STAT5 binding to shared consensus sequences during T cell differentiation, favoring a pro-inflammatory phenotype. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eAlthough the effects of IL-1β on Th17 cells are well characterized, its impact on Tc17 or tissue-resident memory (TRM17) cells has not been fully elucidated. In this study, we demonstrate that elevated IL-1β levels in psoriasis promote hyperactivation of the IRAK4\u0026ndash;NF-κB signaling cascade in Tc17 and TRM17 cells. This leads to a sequential downregulation of SOCS3, upregulation of STAT3, and suppression of STAT5 expression, findings consistent with previous studies in Th17 cells. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eThe SOCS family primarily functions to inhibit cytokine signaling by suppressing STAT activation through JAK\u0026ndash;STAT receptor pathways. Among these, SOCS1 and SOCS3 have been most extensively studied due to their ability to directly bind JAKs and limit inflammatory signaling. [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] Genome-wide association studies have identified SOCS1 as a susceptibility locus in psoriasis, whereas SOCS3 polymorphisms do not appear to be associated with disease risk. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] Functionally, SOCS3 provides a negative feedback mechanism that rapidly terminates IL-6 and IL-23 receptor signaling by inhibiting receptor-bound JAK1 and JAK2, respectively. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] SOCS3 expression is reduced in psoriatic T cells, and conditional SOCS3 deletion in keratinocytes has been associated with exacerbated epidermal hyperplasia, CD11\u003csup\u003e+\u003c/sup\u003e dendritic cell infiltration, and inflammation independent of T and B cells, reinforcing its potential as a biomarker and therapeutic target in psoriasis. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eCompared with the BALB/c psoriasis group, our results showed significantly reduced SOCS3 expression and increased pSTAT3 levels in both splenic and cutaneous tissues of the IL-1RaKO group. Intriguingly, the BALB/c group exhibited an expansion of CD25\u003csup\u003e+\u003c/sup\u003eFOXP3\u003csup\u003e+\u003c/sup\u003e Tregs and elevated levels of both STAT5 and SOCS3. In contrast, the IL-1RaKO group exhibited increased STAT3 and decreased STAT5 expression, likely driven by enhanced IRAK4\u0026ndash;NF-κB pathway activation. These findings suggested the presence of a functional SOCS3/STAT3 negative feedback loop in the BALB/c group, which appeared to be disrupted in the IL-1RaKO group due to elevated IL-1β. This disruption may underlie the observed imbalance in STAT signaling.\u003c/p\u003e\u003cp\u003eMoreover, our data suggested that pSTAT3, when acting independently, may contribute to the transcriptional regulation of SOCS3 to moderate inflammatory responses. However, concurrent activation of both pNF-κB and pSTAT3 appears to suppress SOCS3 expression entirely, potentially initiating a non-specific and sustained inflammatory cascade. [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eOur results demonstrated that T cell subsets exhibiting SOCS3 downregulation in conjunction with STAT3 upregulation included both IL-17\u0026ndash;producing CD4\u003csup\u003e+\u003c/sup\u003e T cells and IL-17\u0026ndash;producing CD8\u003csup\u003e+\u003c/sup\u003e T cells. We particularly focused on the CD8\u003csup\u003e+\u003c/sup\u003e T cell compartment because IL-17\u003csup\u003e+\u003c/sup\u003e CD4\u003csup\u003e+\u003c/sup\u003e T cells generally respond well to biologic therapies targeting IL-17A or IL-23; IL-17\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e T cell subsets, including TRMs, often exhibit therapeutic resistance. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eUnder conditions of elevated IL-1β, we observed substantial expansion of CD103\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e T cells, a population typically identified as TRM. Although CD69\u003csup\u003e+\u003c/sup\u003eCD103\u003csup\u003e+\u003c/sup\u003e expression is commonly used to define TRM, prior research has shown that CD69\u003csup\u003ehi\u003c/sup\u003e skin-resident T17 cells exhibit minimal expression of CXCL13 and CD8A, suggesting a predominance of Th17 rather than Tc17 cells within this cluster.\u003csup\u003e37\u003c/sup\u003e Given that CXCL13, a chemokine associated with psoriasis severity and recurrence, is predominantly expressed by CD103\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e T cells, we operationally defined CD103\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e T cells as TRM in this study. [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eImportantly, SOCS3 downregulation, along with simultaneous upregulation of pSTAT3 and pNF-κB, was specifically observed in CD8\u003csup\u003e+\u003c/sup\u003e TRM cells within psoriatic lesions. This dysregulated signaling was accompanied by an increased number of IL-17\u0026ndash;producing CD8\u003csup\u003e+\u003c/sup\u003e TRM cells. In contrast, the frequency of IFN-γ\u0026ndash;producing TRM cells was not correlated with disease severity. Recent findings have indicated that selective depletion of TRM17 cells, while sparing IFN-γ\u0026ndash;producing TRMs, can be achieved by modulating the ICOS\u0026ndash;c-Maf\u0026ndash;IL-7 signaling axis. [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] These molecular alterations promote the development and expansion of IL-17\u0026ndash;expressing CD8\u003csup\u003e+\u003c/sup\u003e TRM cells, a subset increasingly recognized as central to psoriasis pathogenesis. Moreover, we observed a positive correlation between IL-1β levels and the frequency of IL-4\u0026ndash;expressing CD8\u003csup\u003e+\u003c/sup\u003e TRM cells, suggesting a mechanistic link between psoriasis and atopic dermatitis phenotypes.\u003c/p\u003e\u003cp\u003eWe further demonstrated that selective depletion of TRM17 cells could be accomplished via STAT3 inhibition. This finding holds therapeutic relevance, as targeting residual psoriasis-specific TRM cells has emerged as a promising strategy to prevent disease recurrence. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] Several therapeutic agents, including calcipotriol/betamethasone dipropionate, TNF-α inhibitors, IL-17 inhibitors, and IL-23 inhibitors, have been evaluated for their effects on TRM populations. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan additionalcitationids=\"CR41\" citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e42\u003c/span\u003e] However, none have shown complete efficacy in eliminating TRM17 cells, and psoriasis recurrence frequently occurs after treatment discontinuation. This persistence may be driven by IL-1β\u0026ndash;mediated SOCS3 suppression, which facilitates ongoing differentiation and maintenance of Th17 and TRM17 populations.\u003c/p\u003e\u003cp\u003eOur findings suggest that STAT3 inhibition could serve as a novel therapeutic approach capable of overcoming this limitation. Although Miyoshi et al. [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e] previously proposed the utility of the STAT3 inhibitor STA-21 in psoriasis, their investigation primarily focused on keratinocyte biology. STA-21 was able to inhibit keratinocyte proliferation by downregulating c-Myc and cyclin D1, while promoting the expression of involucrin, transglutaminase 1, and keratin 10. Topical application of 0.2% STA-21 cream for 2 weeks led to substantial clinical improvement in psoriasis patients. [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eIn summary, our data showed that IL-1β promotes the expansion of Tc17 and TRM17 cells by suppressing SOCS3 expression and subsequently upregulating STAT3 via the IRAK4\u0026ndash;NF-κB pathway. STAT3 inhibition may exert therapeutic effects in psoriasis through multiple mechanisms: attenuating Th17 and TRM17 differentiation, inhibiting IL-17\u0026ndash;driven STAT3 signaling, reversing IL-1β\u0026ndash;mediated SOCS3 suppression, promoting STAT5 expression, restoring SOCS3 levels, and inhibiting keratinocyte hyperproliferation.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, our findings demonstrate that dysregulated IL-1β signaling in psoriasis suppresses SOCS3 which is mediated by simultaneously over activated NF-κB-STAT3 vicious cycle, disrupting the balance between pro-inflammatory and regulatory T cells and promoting the expansion of pathogenic Th17, Tc17, and TRM17 populations-particularly the CD8\u0026thinsp;+\u0026thinsp;TRM17 subset that contributes to therapeutic resistance and disease recurrence. Importantly, STAT3 inhibition not only restores SOCS3 expression and regulatory T cell function by pSTAT5 upregulation but also selectively depletes TRM17 cells by cutting of NF-κB-STAT3 vicious axis and reduces keratinocyte hyperproliferation, highlighting STAT3 as a promising therapeutic target to overcome the limitations of current psoriasis treatments.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eTRM, Tissue resident memory;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSOCS3, Suppressor of Cytokine Signaling 3;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIL-1RaKO,\u0026nbsp;Interleukin-1 Receptor Antagonist Knockout;\u003c/p\u003e\n\u003cp\u003eSTAT3,\u0026nbsp;Signal Transducer and Activator of Transcription3\u003c/p\u003e\n\u003cp\u003eNF-\u0026kappa;B, Nuclear factor kappa-light-chain-enhancer of activated B cells\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAll experimental procedures were approved by the Institutional Animal Care and Use Committee (IACUC), Department of Laboratory Animals, College of Medicine, Catholic University of Korea, and complied with the guidelines of the National Institutes of Health. (Permit Number: 2023-0110-02). And all procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.(KC17TNSI0237, KC22SISI0408)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by two grants from the National Research Foundation of Korea (NRF), funded by the Korea government (Ministry of Science and ICT, MSIT) under grant numbers RS-2024-00454685 and RS-2024-00347600. The funding provided by these NRF grants contributed to all stages of the research, including study design, data collection, analysis, and manuscript preparation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eK.T.H. performed the majority of the experiments, including animal studies, ex vivo flow cytometry, tissue staining (H\u0026amp;E, IHC, and confocal staining), and data analysis. L.C.L. was responsible for CD8 T cell isolation and in vitro experiments. L.S.Y. and L.A.R. reviewed all experimental data and ensured data integrity. L.Y.J. prepared the summary figures. B.C.H. provided blood and tissue samples from psoriasis patients, contributed to clinical discussions, and offered experimental ideas. C.M.L. conceived the overall experimental design and supervised the project.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll information obtained or evaluated throughout this research is provided within this published. Original datasets can also be obtained from the corresponding author upon appropriate request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors have given their consent for the publication of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors declare that they have no conflicts of interest to disclose\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGriffiths CEM, Armstrong AW, Gudjonsson JE, Barker J. 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Science. 2023;382:1073\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFrancis L, Capon F, Smith CH, Haniffa M, Mahil SK. Inflammatory memory in psoriasis: From remission to recurrence. J Allergy Clin Immunol. 2024;154:42\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKurihara K, Fujiyama T, Phadungsaksawasdi P, Ito T, Honda T, Tokura Y. Epidermal CD8(+)CD103(+) skin resident memory T cells in psoriasis plaques are reduced in number but remain in the basement membrane zone after topical application of corticosteroid and vitamin D3. J Dermatol Sci. 2022;105:192\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMashiko S, Edelmayer RM, Bi Y, Olson LM, Wetter JB, Wang J, et al. Persistence of Inflammatory Phenotype in Residual Psoriatic Plaques in Patients on Effective Biologic Therapy. J Invest Dermatol. 2020;140:1015\u0026ndash;e254.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMiyoshi K, Takaishi M, Nakajima K, Ikeda M, Kanda T, Tarutani M, et al. Stat3 as a Therapeutic Target for the Treatment of Psoriasis: A Clinical Feasibility Study with STA-21, a Stat3 Inhibitor. J Invest Dermatology. 2011;131:108\u0026ndash;17.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-translational-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jtrm","sideBox":"Learn more about [Journal of Translational Medicine](http://translational-medicine.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/jtrm/default.aspx","title":"Journal of Translational Medicine","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Psoriasis, STAT3, TRM17, IL-1 receptor antagonist, SOCS3","lastPublishedDoi":"10.21203/rs.3.rs-7432855/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7432855/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eThe accumulation of IL-17\u0026ndash;producing CD8\u003csup\u003e+\u003c/sup\u003e tissue-resident memory T (TRM) cells contributes to chronic and recurrent psoriasis. Suppressor of cytokine signaling 3 (SOCS3) plays a critical role in limiting pSTAT3 and pNF-κB activity to restrain excessive IL-17\u0026ndash;mediated inflammation. This study investigated how IL-1\u0026ndash;induced activation of pSTAT3 and pNF-κB leads to SOCS3 downregulation in CD8\u003csup\u003e+\u003c/sup\u003e TRM cells, facilitating the expansion of IL-17\u003csup\u003e+\u003c/sup\u003e subsets in psoriasis. It also evaluated the therapeutic potential of restoring SOCS3 through targeted STAT3 inhibition and STAT5 activation.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eUsing both \u003cem\u003ein vitro\u003c/em\u003e assays and an IL-1 receptor antagonist knockout mouse model of imiquimod-induced psoriasis, we examined hyperactive IL-1 signaling in CD8\u003csup\u003e+\u003c/sup\u003e TRM cells isolated from ex vivo psoriatic samples. The STAT3 inhibitor STA-21 was used to assess its effect on SOCS3 expression and IL-17\u0026ndash;producing TRM cell frequency.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eHyperactivation of IL-1 signaling in chronic psoriasis established a pathogenic feedback loop in CD8⁺ TRM cells, where elevated pSTAT3 and pNF-κB activity suppressed SOCS3 expression, promoting the expansion of IL-17\u0026ndash;producing CD8⁺ TRM cells and exacerbating disease severity. Therapeutic modulation via STA-21 restored SOCS3 levels, reduced IL-17⁺ TRM cell numbers, and disrupted this inflammatory cycle. Dual regulation of STAT3 inhibition and STAT5 activation emerged as a promising approach to attenuate psoriatic inflammation.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eOur findings highlight the IL-1/pNF-κB/pSTAT3 axis in CD8⁺ TRM cells as a central driver of psoriasis pathogenesis. Restoring SOCS3 expression through combined STAT3 inhibition and STAT5 activation offers a novel immunomodulatory strategy for treating severe or recurrent psoriasis.\u003c/p\u003e","manuscriptTitle":"IL-1β–induced STAT3 activation drives IL-17–producing CD8⁺ tissue-resident memory T cells and exacerbates chronic psoriasis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-04 11:20:21","doi":"10.21203/rs.3.rs-7432855/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-08-28T16:38:42+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-28T06:29:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-25T15:00:18+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Translational Medicine","date":"2025-08-22T05:04:11+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-translational-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jtrm","sideBox":"Learn more about [Journal of Translational Medicine](http://translational-medicine.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/jtrm/default.aspx","title":"Journal of Translational Medicine","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a179fdf6-8939-4f9a-89a9-a936a169ad9e","owner":[],"postedDate":"September 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-12-15T16:06:07+00:00","versionOfRecord":{"articleIdentity":"rs-7432855","link":"https://doi.org/10.1186/s12967-025-07446-7","journal":{"identity":"journal-of-translational-medicine","isVorOnly":false,"title":"Journal of Translational Medicine"},"publishedOn":"2025-12-09 15:59:35","publishedOnDateReadable":"December 9th, 2025"},"versionCreatedAt":"2025-09-04 11:20:21","video":"","vorDoi":"10.1186/s12967-025-07446-7","vorDoiUrl":"https://doi.org/10.1186/s12967-025-07446-7","workflowStages":[]},"version":"v1","identity":"rs-7432855","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7432855","identity":"rs-7432855","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}