CHI3L1 regulates chondrocytes function via JAK2/STAT3 signaling pathway during lumbar facet joint degeneration

CHI3L1 regulates chondrocytes function via JAK2/STAT3 signaling pathway during lumbar facet joint degeneration | 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 CHI3L1 regulates chondrocytes function via JAK2/STAT3 signaling pathway during lumbar facet joint degeneration Yuanzhen Chen, Zongbo Qin, Liangyu Xie, Shengnan Cao, Ziteng Li, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8782502/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 11 You are reading this latest preprint version Abstract Purpose : Low back pain (LBP) is a global public health concern closely linked to lumbar facet joint (FJ) degeneration, yet its specific pathogenesis remains unclear. CHI3L1 (chitinase 3 like 1) is involved in inflammation and tissue remodeling, but its role in FJ degeneration is poorly understood. This study aimed to investigate the correlation between CHI3L1 and lumbar FJ degeneration, clarify its regulatory effects on chondrocyte functions, and explore the underlying molecular mechanisms. Methods : Forty human lumbar FJ cartilage tissues were collected to detect CHI3L1 expression via RT-qPCR. In vitro experiments were performed on human chondrocytes treated with recombinant CHI3L1 protein or CHI3L1 siRNA, including cell proliferation, cell cycle, apoptosis, ELISA and western blot. Protein expression microarray was used to identify downstream signaling pathways. In vivo experiments were conducted on FJ degeneration rat models injected with sh-CHI3L1 vector, followed by HE staining for histopathological observation. Results : We found CHI3L1 expression was significantly elevated in degenerated FJ cartilage and positively correlated with degeneration stages. In vitro, CHI3L1 inhibited chondrocyte proliferation, induced G1 phase arrest, promoted apoptosis, and upregulated the expression of inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α). Silencing CHI3L1 reversed these effects. Mechanistically, CHI3L1 regulated inflammatory cytokine expression through activating the JAK2/STAT3 signaling pathway. In vivo, knockdown of CHI3L1 significantly attenuated FJ degeneration in rats. Conclusions : CHI3L1 plays a pivotal role in lumbar FJ degeneration by regulating chondrocyte viability and inflammatory responses via the JAK2/STAT3 signaling pathway. CHI3L1 may serve as a potential biomarker and therapeutic target for FJ degenerative diseases. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Low back pain (LBP) is a prevalent global public health concern, with a lifetime prevalence of up to 84% and 11-12% disability rate, and 23% of patients develop chronic LBP, imposing heavy socioeconomic burdens[1]. General risk factors for LBP include age, muscle weakness in the back and/or abdomen, psychosocial factors, occupation, obesity, smoking, etc[2]. With increasing age, vertebral column degeneration has become the main pathological factor leading to LBP. Facet joint (FJ) degeneration, which involves in vertebral functional failure, has been reported to be commonly associated with spinal degenerative diseases such as facet joint osteoarthritis (FJOA), lumbar intervertebral disc herniation (LIDH) and so on[3]. Facet joints (FJs), paired spinal diarthrodial joints, arise from posterolateral articulation of superior (SAP) and inferior (IAP) articular processes between adjacent vertebrae[4]. FJs represent the only synovial joints of spine. SAP and IAP are lined with articular hyaline cartilage over the subchondral bone[4]. FJ paly important functions in maintaining the spinal structure and physiological function, enabling spinal alongside movements as extension, flexion and rotation. Researchers have reported the anatomical factors and biomechanical predisposition are closely associated with FJ degeneration[5]. Despite intensive research in this field, little is known about specific pathogenesis and biological mechanisms of FJ degeneration. It is reported that FJ cartilage degeneration can begin as early as age 15 years, and reached about 80% in elderly adults[6]. The hyaline cartilage of FJ is characterized by poor vascularization and cellular infiltration, featuring a considerable healing inability after traumatization. FJ cartilage degeneration begin with fibrillation and shallow pitting that affect the cartilage surface focally[7]. Whereafter, cartilage become deeper fibrillation and fissuring, flaking and pitting, then erosion down to subchondral bone, contributing to facet hypertrophy, stenosis, destabilization of the three-joint complex (two allied FJs and intervertebral disc) and then LBP[8]. The joint capsule might show fibrosis and increased vascularization at onset of degeneration. Immune cells and inflammatory response have been found to be existed in the early stage of FJ degeneration[9]. Many cytokine mediators of inflammation and angiogenesis have been implicated as participants in FJ degeneration. Whereas, the exact mechanisms of inflammation and cytokines during the process of FJ cartilage degeneration have not been completely elucidated. CHI3L1 (chitinase 3 like 1), a glycoprotein member of the glycosyl hydrolase 18 family, is secreted by activated macrophages, chondrocytes, neutrophils and synovial cells[10]. The protein plays a role in the process of inflammation and tissue remodeling. CHI3L1 has been reported to be significantly associated with kinds of diseases, such as Alzheimer, cancer, and osteoarthritis[11]. However, the role of CHI3L1 in FJ cartilage degeneration are less well documented. In the present study, we analyzed the correlation between CHI3L1 expression and lumbar FJ degeneration. We investigated the role of CHI3L1 in regulating biological functions of chondrocytes and its molecular mechanism in participating FJ degeneration. Our study provides a potential biomarker for clinical diagnosis and therapy of FJ degenerative diseases. Methods Cell Culture Human chondrocytes obtained from the Procell company (Procell, Cat NO. CP-H107) were cultured in DM/F12 complete medium (Cat NO. CM-H107, Procell, Wuhan, China) at 37°C with 5% CO 2 . Chondrocyte purity (90%) was confirmed by COLII immunofluorescence. For MTT, cell cycle and apoptosis assays, chondrocytes were treated with 10 µg/ml recombinant human CHI3L1 (Abcam) for 24h, or transfected with CHI3L1 siRNA, JAK2 siRNA, or overexpression vectors. Patients and tissue Samples Forty surgical FJ cartilage specimens were collected from patients (Table 1 ) with lumbar degenerative diseases (Shandong Provincial Hospital, 960th Hospital of PLA, Taian City Central Hospital), including 7 normal, 9 stage I, 18 stage II, and 6 stage III degenerated samples (graded by MRI/CT). The study was approved by the Ethics Committee of Shandong First Medical University, with informed consent from all participants. RT-qPCR Total RNA was extracted with TRIzol (Invitrogen) and reverse-transcribed to cDNA (Evo M-MLV RT Premix, Accurate Biology). RT-qPCR was performed with BeyoFast™ SYBR Green One-Step qRT-PCR Kit (Beyotime) on an ABI 7900HT system. Primers: CHI3L1 (forward: 5'-CTACCCTGGACGGAGAGACA-3', reverse: 5'-GGACTTGCATCCTCCTGACC-3'); GAPDH (forward: 5'-AGAAGGCTGG GGCTCATTTG-3', reverse: 5'-AGGGGCCATCCACAGTCTTC-3'). Relative expression was calculated by the 2-ΔCT method. Cell Proliferation, Cycle and Apoptosis Assays Cell proliferation was detected by MTS assay (Promega) in 96-well plates. For cell cycle analysis, chondrocytes were fixed with 75% ethanol, treated with RNase, stained with PI and analyzed by flow cytometry (Agilent). Apoptosis was assessed using Annexin V-FITC/PI staining (Meilunbio) and flow cytometry. All assays were performed in triplicate. ELISA and Western Blot Inflammatory cytokine concentrations (IL-1β, IL-6, IL-8, TNF-α) were measured by ELISA kits (Cloud-Clone Corp). For western blot, proteins were extracted with RIPA lysis buffer (Beyotime), separated by SDS-PAGE, transferred to PVDF membranes, and probed with primary antibodies (JAK2, STAT3, MYC, IL-1β, IL-6, IL-8, TNF-α, GAPDH; Proteintech) and HRP-conjugated secondary antibodies (ZSGB). Bands were visualized by ECL (Cell Signaling Technology). Plasmid Transfection CHI3L1 shRNA plasmid (OBiO Technology), JAK2 overexpression vector (OE-JAK2, Genechem), and siRNAs (CHI3L1 siRNA-1/-2/-3, JAK2 siRNA-1/-2/-3, negative control; Hippobio) were transfected into chondrocytes using Lipofectamine 2000 or RNAi MAX (Invitrogen) per manufacturer’s protocols. Protein Microarray Differentially expressed proteins between CHI3L1-treated and control chondrocytes were analyzed using the CSP100 plus chip (Wayen Biotechnologies). Filters: log2∣fold change∣≥1.3, P < 0.05. KEGG enrichment analysis identified signaling pathways. Rat FJ Degeneration Model Twenty-one 4-week-old male Sprague-Dawley rats were randomly divided into sham (n = 7), FJ model (n = 7), and sh-CHI3L1 (n = 7) groups. FJ degeneration was induced by removing the right L4/5 articular processes. sh-CHI3L1 vector (10 µg/5 µL saline) was injected into the left FJ of the sh-CHI3L1 group. Rats were sacrificed at 3 months post-surgery, and left FJ cartilage was collected for HE staining. Animal experiments were approved by the institutional ethics committee. Statistical Analysis Data were analyzed using SPSS 25.0. Student’s t-test compared two groups, and ANOVA analyzed proliferation curves. Results are presented as mean ± SD. P < 0.05 was statistically significant. Results CHI3L1 expression is significantly associated with FJ degeneration RT-qPCR results showed significantly higher CHI3L1 mRNA expression in degenerated FJ cartilage compared with normal samples (P = 0.0031, Fig. 1 A). Moreover, CHI3L1 expression progressively increased with advancing FJ degeneration stages (P < 0.05, Fig. 1 B). These results suggested that CHI3L1 play important roles in the process of FJ cartilage degeneration. CHI3L1 inhibits biological functions of chondrocytes Recombinant CHI3L1 significantly suppressed chondrocyte proliferation, with OD490 values decreasing markedly at 72 h and maintaining this downward trend through 120 h(P < 0.05, Fig. 2 A). The effect of CHI3L1 expression on chondrocyte cell cycle was further assessed by flow cytometry. Compared with the control group, G1-phase cell proportion was significantly elevated (Fig. 2 B), indicating that CHI3L1 induced G1-phase arrest. Cell apoptosis investigation indicated the apoptotic rate of chondrocytes treated with CHI3L1 was significantly higher than that observed in the control group (Fig. 2 C). To further explore the role of CHI3L1 in chondrocytes, three CHI3L1 siRNAs (siRNA-1, 2 and 3) were transfered into cells, with siRNA-3 showing optimal knockdown efficiency by RT-qPCR (Fig. 2 D). Subsequent assays revealed that CHI3L1 silencing promoted chondrocyte proliferation (Fig. 2 E), induced G1-to-S phase transition (Fig. 2 F) and suppressed chondrocyte apoptosis (Fig. 2 G). CHI3L1 promotes expression of inflammatory cytokines Since inflammation is one of the major causes of FJ degeneration, we explored whether CHI3L1 has effect on the expression of inflammatory cytokines of chondrocytes. After treating with CHI3L1, IL-8 and TNF-α secreted by chondrocytes were significantly increased compared with the control group (Fig. 3 A). Simultaneously, IL-8 and TNF-α secreted by chondrocytes transfected with siRNA-3 were significantly decreased compared with the siRNA-NC control group (Fig. 3 B). These results suggested the potential function of CHI3L1 regulating inflammatory cytokines secretion of chondrocytes. CHI3L1 promoted chondrocytes to express inflammatory cytokines of IL-8 and TNF-α. Whereas, silencing CHI3L1 expression downregulated expression of inflammatory cytokines in chondrocytes. CHI3L1 regulates expression of inflammatory cytokines through JAK2/STAT3 signaling pathway in chondrocytes To clarify the molecular mechanism by which CHI3L1 regulates chondrocyte viability, protein microarray combined with bioinformatics and GO enrichment analyses identified the JAK2/STAT3 signaling pathway as a critical target. Key proteins in this pathway (JAK2, STAT2/STAT3, MYC) were significantly upregulated in CHI3L1-treated chondrocytes (Fig. 4 A), and subsequent validation confirmed marked elevation of P-JAK2, P-STAT3 and MYC protein levels (Fig. 4 B, F). Besides, western blot further verified ELISA-indicated changes in the protein expression of inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) (Fig. 4 B, F). To further elucidate whether CHI3L1 regulate expression of inflammatory cytokines through JAK2/STAT3 signaling pathway, we firstly used siRNAs to knockdown expression of JAK2. Results showed that si-JAK2-3 played the highest knockdown efficiency and was then used for all the subsequent experiments (Fig. 4 C). Both the si-NC and si-JAK2-3 transfected chondrocytes were treated with CHI3L1 for 24h. We found that compared with si-NC group, expression of STAT3 and MYC were significantly decreased in chondrocytes transfected with si-JAK2 (Fig. 4 D, F), indicating that JAK2/STAT3 pathway had been downregulated. Simultaneously, expression of IL-1β, IL-6, IL-8 and TNF-α were also reduced (Fig. 4 D). To rescue JAK2 expression, we constructed an overexpression vector (OE-JAK2) and transfected it into chondrocytes. JAK2 rescue upregulated STAT3 and MYC expression, confirming restoration of the JAK2/STAT3 signaling pathway (Fig. 4 E, F). Following CHI3L1 treatment, IL-1β, IL-6, IL-8 and TNF-α expression was elevated compared with the si-JAK2 group, yet remained lower than that in the si-NC group (Fig. 4 E). Collectively, these results indicate that CHI3L1 regulates inflammatory cytokine expression in chondrocytes primarily via the JAK2/STAT3 signaling pathway. Knockdown of CHI3L1 inhibits FJ degeneration in vivo To further investigate the effect of CHI3L1 on FJ degeneration in vivo, we established L4/5 FJ degenerative rat model. The left L4/5 FJ degeneration model was confirmed to be established successfully through HE staining. The sh-CHI3L1 vector were constructed and injected into the left L4/5 FJ capsule to knockdown CHI3L1 expression in chondrocytes. Comparing HE staining results of FJ cartilage tissues between three groups, we found that in the normal control group, normal facet joint with no joint-space narrowing, normal thickness of articular cartilage, regular cartilage margins, homogeneously distributed chondrocytes, clear boundary line between cartilage and subchondral bone, and no subchondral erosions (Fig. 5 A). In the model group, we found the degenerated FJ with joint-space narrowing, coarse cartilage margins followed by fissuring and flaking, thinning cartilage, blurry boundary line between cartilage and subchondral bone, subchondral erosions, heterogeneously distributed chondrocytes, much more hypertrophic chondrocytes and some necrosis (Fig. 5 B). Comparing with model group, the sh-CHI3L1 treated group showed attenuate FJ degeneration with clear cartilage margins and boundary line between cartilage and subchondral bone, no cartilage flaking and subchondral erosions, distributed chondrocytes with some hypertrophic chondrocytes but no necrosis (Fig. 5 C). The results of suggested that sh-CHI3L1 injection significantly attenuate FJ degeneration in rat. Discussion FJ cartilage is a tissue composed of chondrocytes that wrapped in a collagen rich extracellular matrix (ECM) they synthesize. FJ cartilage degeneration is caused by multifactorial parameters, including accelerated chondrocyte hypertrophy, excessive production of matrix degrading enzymes such as matrix metallo proteinases (MMPs) and aggrecanases, and increased focal calcification of joint cartilage[ 12 ]. With onset of cartilage degeneration, chondrocytes undergo multiple changes, in terms of proliferation, viability, hypertrophy and secretory profile including inflammatory cytokines. Eventually, chondrocytes undergo apoptosis and cell death, which leads to destruction of cartilage tissues. Between the series regulatory processes, inflammatory cytokines are highly relevant to the onsets, pathogenesis, and progression of FJ degeneration[ 13 ]. In the current study, we investigated the role of CHI3L1 in chondrocytes and FJ cartilage degeneration. CHI3L1, also known as YKL-40, is an inflammatory cytokine that has been reported in multiple researches[ 13 ]. It plays a major role in tissue injury, inflammation, tissue repair, and remodeling responses. From the clinical FJ cartilage specimens, markedly elevated CHI3L1 expression in degenerative samples aroused our interesting. Wang et al found that CHI3L1 was highly expressed in the degenerated nucleus pulposus tissues[ 14 ]. The level of CHI3L1 in synovial fluid of active knee osteoarthritis patients was significantly higher comparing with age-matched healthy controls. Connor JR et al confirmed that CHI3L1 expression increased in cartilage tissues from patients with osteoarthritic as disease progresses[ 15 ]. Our data showed that CHI3L1 expression was progressively increased with the FJ degeneration stage increased. Taken together, these studies suggest that the inflammatory factor CHI3L1 present an elevated level in cartilage degenerated diseases, and may play an important role in the disease progress. The role of CHI3L1 in regulating viability of chondrocytes remains controversial. Recombinant CHI3L1 has been found to reduce the percentage of apoptotic nucleus pulposus cells, and CHI3L1 blocking increase the percentage of apoptotic nucleus pulposus cells[ 16 ]. Johansen JS et al reported that CHI3L1 protein expression is high in cell types characterized by rapid proliferation[ 17 ]. Whereas, Connor JR et al reported that proliferating osteoblasts expressed low to moderate levels of CHI3L1[ 15 ]. Our present study found that, in vitro recombinant CHI3L1 protein significantly inhibited chondrocytes proliferation and cell cycle but promoted apoptosis. Conversely, silencing CHI3L1 expression significantly promoted chondrocytes proliferation and cell cycle, and inhibited apoptosis. Since that different cell types or tissues in different state and development stage were used in these researches, for example, degeneration or normal, early or late development stage, the CHI3L1 may serve as distinct functions on the cell viability. These researches further indicate the complexity of CHI3L1 in regulating cellular biological functions. CHI3L1 have been found to regulate inflammation in multiple diseases[ 18 ]. CHI3L1 can stimulate pro-inflammatory mediators and may play a role in type 2 helper cell-mediated inflammation. The levels of pro-inflammatory mediators such as IL-6, IFN-γ, and TNF-α, were found to be correlated with the level of CHI3L1 in rheumatoid arthritis patients. Attur MG et al reported that IL-1β and TNF-α participated in the destruction of articular cartilage matrix by inducing chondrocytes secretion of matrix degrading enzymes[ 19 ]. Gómez R et al found that adipokines including leptin and adiponectin can induce the production of pro-inflammatory IL-8 and pro-catabolic MMPs by chondrocytes, and contribute to cartilage damage[ 20 ]. Besides, IL-6, IL-15, IL-17, IL-18 and IL-21 have also been shown to be implicated in osteoarthritis. In our current study, results confirmed that the expression of IL-1β, IL-6, IL-8 and TNF-α were markedly elevated in chondrocytes treated with CHI3L1. Knockdown CHI3L1 expression significantly inhibited the expression of IL-8 and TNF-α. Taken together of these studies, CHI3L1 may contribute to the FJ cartilage degeneration through promoting pro-inflammatory cytokines in chondrocytes. CHI3L1 has been reported to induce pro-inflammatory molecules through different signaling pathways including NF-κB, TGF-β, and Wnt/β in various pathological process[ 21 ]. Researchers have investigated the biological mechanisms of CHI3L1 in cartilage degenerative diseases. Wang R et al reported that CHI3L1 protected nucleus pulposus via AKT3 signaling during intervertebral disc degeneration[ 16 ]. Jin T et al found that CHI3L1 promotes Staphylococcus aureus-induced osteomyelitis by activating p38/MAPK and Smad signaling pathways[ 22 ]. In the present study, to further elucidate the molecular mechanism of CHI3L1 in regulating chondrocytes viability and FJ cartilage degeneration, we investigated protein expression microarray. Results confirmed that CHI3L1 promoted chondrocytes to express IL-1β, IL-6, IL-8 and TNF-α through JAK2/STAT3 signaling pathway. Furthermore, in vivo experiments found that knockdown CHI3L1 expression can effectively attenuate FJ cartilage degeneration in rat model. Comprehensively, our research supports that CHI3L1 promote FJ cartilage degeneration through regulating expression of inflammatory cytokines and cell viability of chondrocytes. Declarations Author Contribution BSand BBS designed the research, acquired funding and revised the paper; YZC and ZBQ performed the experiment; LYX, SNC, ZTLand LW collected samples and analyzed clinical data; YZC and ZBQ wrote the paper. References Hartvigsen J, Hancock MJ, Kongsted A, Louw Q, Ferreira ML, Genevay S, Hoy D, Karppinen J, Pransky G, Sieper J, Smeets RJ, Underwood M, Lancet Low Back Pain Series Working G (2018) What low back pain is and why we need to pay attention. 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Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 26 Apr, 2026 Reviews received at journal 26 Apr, 2026 Reviews received at journal 02 Apr, 2026 Reviews received at journal 29 Mar, 2026 Reviewers agreed at journal 25 Mar, 2026 Reviewers agreed at journal 24 Mar, 2026 Reviewers agreed at journal 24 Mar, 2026 Reviewers invited by journal 08 Feb, 2026 Editor assigned by journal 04 Feb, 2026 Submission checks completed at journal 04 Feb, 2026 First submitted to journal 04 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8782502","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":588894553,"identity":"afe2295c-fa81-4558-869a-c3b5758b01f4","order_by":0,"name":"Yuanzhen Chen","email":"","orcid":"","institution":"The Second Affiliated Hospital of Shandong First Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yuanzhen","middleName":"","lastName":"Chen","suffix":""},{"id":588894554,"identity":"6d22fcb7-d6a9-4bda-9de2-53d713d2a4b5","order_by":1,"name":"Zongbo Qin","email":"","orcid":"","institution":"Shandong First Medical University","correspondingAuthor":false,"prefix":"","firstName":"Zongbo","middleName":"","lastName":"Qin","suffix":""},{"id":588894555,"identity":"a17e5fba-0112-4e88-babc-9ecf56935ca4","order_by":2,"name":"Liangyu Xie","email":"","orcid":"","institution":"Shandong First Medical University","correspondingAuthor":false,"prefix":"","firstName":"Liangyu","middleName":"","lastName":"Xie","suffix":""},{"id":588894557,"identity":"d15defb9-4004-4fe7-a7f7-9e905771c20f","order_by":3,"name":"Shengnan Cao","email":"","orcid":"","institution":"Neck-Shoulder and Lumbocrural Pain Hospital of Shandong First Medical University","correspondingAuthor":false,"prefix":"","firstName":"Shengnan","middleName":"","lastName":"Cao","suffix":""},{"id":588894558,"identity":"e0e36e08-bca8-4a68-94f1-e5b261d54430","order_by":4,"name":"Ziteng Li","email":"","orcid":"","institution":"Tengzhou Central People's Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ziteng","middleName":"","lastName":"Li","suffix":""},{"id":588894559,"identity":"731677ac-2933-4563-ae43-3ada6757224e","order_by":5,"name":"Lei Wang","email":"","orcid":"","institution":"PLA 960th Hospital","correspondingAuthor":false,"prefix":"","firstName":"Lei","middleName":"","lastName":"Wang","suffix":""},{"id":588894560,"identity":"794cee33-6a6c-45d2-9e44-876e5804aaa5","order_by":6,"name":"Beibei Sun","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxUlEQVRIiWNgGAWjYBACAwkQWcHA2N4AYrARreUMA2PPAZK0MLaRosVcuv2ZdOG8OtkeiewEhg9lhxn4Zzfg12I554yZ9Mxth417JHI3MM44d5hB4s4BAg67kcMmzbvtQOJ+oBZm3rbDQKcmENKS/kyad05dIsgW5r/EaUkwk+ZtYIZoYSRGC9AvxtY8x4B+4Xm74WDPuXQeiRsEtABD7OFtnhpgiLHnbnzwo8xajn8GAS0o4AAQ85CgfhSMglEwCkYBLgAAb+JCuUTGR2AAAAAASUVORK5CYII=","orcid":"","institution":"Shandong First Medical University","correspondingAuthor":true,"prefix":"","firstName":"Beibei","middleName":"","lastName":"Sun","suffix":""},{"id":588894561,"identity":"c34c2801-1a38-4841-8064-2833fb88325d","order_by":7,"name":"Bin Shi","email":"","orcid":"","institution":"Neck-Shoulder and Lumbocrural Pain Hospital of Shandong First Medical University","correspondingAuthor":false,"prefix":"","firstName":"Bin","middleName":"","lastName":"Shi","suffix":""}],"badges":[],"createdAt":"2026-02-04 06:24:51","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8782502/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8782502/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102498656,"identity":"95b97a53-bf70-441e-9553-061b3d18567d","added_by":"auto","created_at":"2026-02-12 10:05:26","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":67009,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCHI3L1 mRNA expression in human facet joint (FJ) cartilage tissues detected by real-time quantitative PCR\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) Relative CHI3L1 mRNA levels were markedly upregulated in degenerated FJ cartilage specimens (n=33) compared with normal tissues (n=7, P=0.0031).\u003c/p\u003e\n\u003cp\u003e(B) CHI3L1 mRNA expression showed a progressive elevation with the aggravation of FJ cartilage degeneration. Compared with the normal group, its expression was significantly increased in degeneration stage Ⅰ (n=9), stage Ⅱ (n=18, P=0.0049) and stage Ⅲ (n=6, P=0.0004), with a significant difference also observed between stage Ⅱ and stage Ⅲ (P=0.0046). Horizontal lines denote the mean value.\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8782502/v1/1f40300e141530b9b13e2471.jpg"},{"id":102746155,"identity":"a760ac7b-6f6c-45fb-b46a-459c65f3b1cf","added_by":"auto","created_at":"2026-02-16 08:55:52","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":213541,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCHI3L1 exerts inhibitory effects on chondrocyte biological functions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) CHI3L1 treatment significantly suppressed chondrocyte proliferation at 72 h, 96 h and 120 h.\u003c/p\u003e\n\u003cp\u003e(B) Cell cycle analysis demonstrated that CHI3L1 induced G1 phase arrest in chondrocytes.\u003c/p\u003e\n\u003cp\u003e(C) CHI3L1 promoted chondrocyte apoptosis.\u003c/p\u003e\n\u003cp\u003e(D) RT-qPCR assays showed the mRNA expression of CHI3L1 in chondrocytes transfected with siRNA-1, siRNA-2 or siRNA-3 for 48 h, with siRNA-3 exhibiting the highest knockdown efficiency.\u003c/p\u003e\n\u003cp\u003e(E) CHI3L1 silencing significantly enhanced chondrocyte proliferation relative to the control group.\u003c/p\u003e\n\u003cp\u003e(F) CHI3L1 silencing facilitated chondrocyte cell cycle progression.\u003c/p\u003e\n\u003cp\u003e(G) CHI3L1 silencing attenuated chondrocyte apoptosis compared with the control group.\u003c/p\u003e\n\u003cp\u003eData are presented as mean±standard deviation (SD) from at least three independent experiments. **, P \u0026lt; 0.01; ***, P \u0026lt; 0.001.\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8782502/v1/39979a27b6a4a1f720676ed2.jpg"},{"id":102498657,"identity":"7b5d854b-99bd-4a6c-99c5-3fd364fad917","added_by":"auto","created_at":"2026-02-12 10:05:26","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":91135,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe effect of CHI3L1 on expression of inflammatory cytokines in chondrocytes.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) CHI3L1 promoted chondrocytes to express inflammatory cytokines of IL-8 and TNF-α.\u003c/p\u003e\n\u003cp\u003e(B) Silencing CHI3L1 expression downregulated expression of IL-8 and TNF-α in chondrocytes. The results are expressed as mean±standard deviation (SD) of at least three independent experiments. *, P \u0026lt; 0.05; **, P \u0026lt; 0.01; ***, P \u0026lt; 0.001.\u003c/p\u003e","description":"","filename":"Fig3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8782502/v1/52441a883ae7e50bad5dbcaa.jpg"},{"id":102498659,"identity":"cca49fa8-0aea-4e85-bc76-10bb0216d344","added_by":"auto","created_at":"2026-02-12 10:05:26","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":67797,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCHI3L1 modulates inflammatory cytokine expression via the JAK2/STAT3 signaling pathway in chondrocytes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) Protein microarray profiling mapped the JAK2/STAT3 signaling pathway, where red and green plots indicate upregulated and downregulated proteins, respectively.\u003c/p\u003e\n\u003cp\u003e(B, F) Western blot assays revealed that CHI3L1 enhanced the expression of phosphorylated JAK2 (P-JAK2), phosphorylated STAT3 (P-STAT3) and MYC, as well as the inflammatory cytokines IL-1β, IL-6, IL-8 and TNF-α in chondrocytes.\u003c/p\u003e\n\u003cp\u003e(C) RT-qPCR analysis showed the mRNA levels of JAK2 in chondrocytes transfected with si-JAK2-1/2/3 for 48 h, with si-JAK2-3 achieving the optimal knockdown efficiency.\u003c/p\u003e\n\u003cp\u003e(D, F) Western blot results demonstrated that JAK2 silencing downregulated P-JAK2, P-STAT3 and MYC expression, and attenuated the upregulation of IL-1β, IL-6, IL-8 and TNF-α induced by recombinant CHI3L1 protein in chondrocytes.\u003c/p\u003e\n\u003cp\u003e(E, F) Western blot assays confirmed that JAK2 rescue restored the expression of P-STAT3 and MYC, and reversed the inhibitory effects of JAK2 silencing on IL-1β, IL-6, IL-8 and TNF-α levels in recombinant CHI3L1-treated chondrocytes.\u003c/p\u003e","description":"","filename":"Fig4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8782502/v1/ac635b9e5cabb6f39071b964.jpg"},{"id":102498660,"identity":"597dc8a4-c524-4867-9e72-4af09c032060","added_by":"auto","created_at":"2026-02-12 10:05:26","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":5396031,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKnockdown of CHI3L1 inhibits facet joint (FJ) degeneration in rats.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) The Sham group showing normal FJ with no joint-space narrowing, normal thickness of articular cartilage, regular cartilage margins, homogeneously distributed chondrocytes, clear boundary line between cartilage and subchondral bone, and no subchondral erosions.\u003c/p\u003e\n\u003cp\u003e(B) FJ model group showing the degenerated FJ with joint-space narrowing, coarse cartilage margins followed by fissuring and flaking, thinning cartilage, blurry boundary line between cartilage and subchondral bone, subchondral erosions, heterogeneously distributed chondrocytes, much more hypertrophic chondrocytes and some necrosis.\u003c/p\u003e\n\u003cp\u003e(C) The sh-chi3l1 treated group showing attenuate FJ degeneration with clear cartilage margins and boundary line between cartilage and subchondral bone, no cartilage flaking and subchondral erosions, distributed chondrocytes with some hypertrophic chondrocytes but no necrosis.\u003c/p\u003e","description":"","filename":"Fig5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8782502/v1/0ba29310cae4ba088e4712e7.jpg"},{"id":104397120,"identity":"2ddc39fc-1b55-4331-ac71-8ef1e8219de3","added_by":"auto","created_at":"2026-03-11 11:29:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6637434,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8782502/v1/a877980d-7d82-4967-be83-9a3a87d5762b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"CHI3L1 regulates chondrocytes function via JAK2/STAT3 signaling pathway during lumbar facet joint degeneration","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLow back pain (LBP) is a prevalent global public health concern, with a lifetime prevalence of up to 84% and 11-12% disability rate, and 23% of patients develop chronic LBP, imposing heavy socioeconomic burdens[1]. General risk factors for LBP include age, muscle weakness in the back and/or abdomen, psychosocial factors, occupation, obesity, smoking, etc[2]. With increasing age, vertebral column degeneration has become the main pathological factor leading to LBP. Facet joint (FJ) degeneration, which involves in vertebral functional failure, has been reported to be commonly associated with spinal degenerative diseases such as facet joint osteoarthritis (FJOA), lumbar intervertebral disc herniation (LIDH) and so on[3].\u003c/p\u003e\n\u003cp\u003eFacet joints (FJs), paired spinal diarthrodial joints, arise from posterolateral articulation of superior (SAP) and inferior (IAP) articular processes between adjacent vertebrae[4]. FJs represent the only synovial joints of spine. SAP and IAP are lined with articular hyaline cartilage over the subchondral bone[4]. FJ paly important functions in maintaining the spinal structure and physiological function, enabling spinal alongside movements as extension, flexion and rotation. Researchers have reported the anatomical factors and biomechanical predisposition are closely associated with FJ degeneration[5]. Despite intensive research in this field, little is known about specific pathogenesis and biological mechanisms of FJ degeneration.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIt is reported that FJ cartilage degeneration can begin as early as age 15 years, and reached about 80% in elderly adults[6]. The hyaline cartilage of FJ is characterized by poor vascularization and cellular infiltration, featuring a considerable healing inability after traumatization. FJ cartilage degeneration begin with fibrillation and shallow pitting that affect the cartilage surface focally[7]. Whereafter, cartilage become deeper fibrillation and fissuring, flaking and pitting, then erosion down to subchondral bone, contributing to facet hypertrophy, stenosis, destabilization of the three-joint complex (two allied FJs and intervertebral disc) and then LBP[8]. The joint capsule might show fibrosis and increased vascularization at onset of degeneration. Immune cells and inflammatory response have been found to be existed in the early stage of FJ degeneration[9]. Many cytokine mediators of inflammation and angiogenesis have been implicated as participants in FJ degeneration. Whereas, the exact mechanisms of inflammation and cytokines during the process of FJ cartilage degeneration have not been completely elucidated.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCHI3L1 (chitinase 3 like 1), a glycoprotein member of the glycosyl hydrolase 18 family, is secreted by activated macrophages, chondrocytes, neutrophils and synovial cells[10]. The protein plays a role in the process of inflammation and tissue remodeling. CHI3L1 has been reported to be significantly associated with kinds of diseases, such as Alzheimer, cancer, and osteoarthritis[11]. However, the role of CHI3L1 in FJ cartilage degeneration are less well documented.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the present study, we analyzed the correlation between CHI3L1 expression and lumbar FJ degeneration. We investigated the role of CHI3L1 in regulating biological functions of chondrocytes and its molecular mechanism in participating FJ degeneration. Our study provides a potential biomarker for clinical diagnosis and therapy of FJ degenerative diseases.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cb\u003eCell Culture\u003c/b\u003e\u003c/p\u003e\u003cp\u003eHuman chondrocytes obtained from the Procell company (Procell, Cat NO. CP-H107) were cultured in DM/F12 complete medium (Cat NO. CM-H107, Procell, Wuhan, China) at 37\u0026deg;C with 5% CO\u003csub\u003e2\u003c/sub\u003e. Chondrocyte purity (90%) was confirmed by COLII immunofluorescence. For MTT, cell cycle and apoptosis assays, chondrocytes were treated with 10 \u0026micro;g/ml recombinant human CHI3L1 (Abcam) for 24h, or transfected with CHI3L1 siRNA, JAK2 siRNA, or overexpression vectors.\u003c/p\u003e\u003cp\u003e\u003cb\u003ePatients and tissue Samples\u003c/b\u003e\u003c/p\u003e\u003cp\u003eForty surgical FJ cartilage specimens were collected from patients (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) with lumbar degenerative diseases (Shandong Provincial Hospital, 960th Hospital of PLA, Taian City Central Hospital), including 7 normal, 9 stage I, 18 stage II, and 6 stage III degenerated samples (graded by MRI/CT). The study was approved by the Ethics Committee of Shandong First Medical University, with informed consent from all participants.\u003c/p\u003e\u003cp\u003e\u003cb\u003eRT-qPCR\u003c/b\u003e\u003c/p\u003e\u003cp\u003eTotal RNA was extracted with TRIzol (Invitrogen) and reverse-transcribed to cDNA (Evo M-MLV RT Premix, Accurate Biology). RT-qPCR was performed with BeyoFast\u0026trade; SYBR Green One-Step qRT-PCR Kit (Beyotime) on an ABI 7900HT system. Primers: CHI3L1 (forward: 5'-CTACCCTGGACGGAGAGACA-3', reverse: 5'-GGACTTGCATCCTCCTGACC-3'); GAPDH (forward: 5'-AGAAGGCTGG GGCTCATTTG-3', reverse: 5'-AGGGGCCATCCACAGTCTTC-3'). Relative expression was calculated by the 2-ΔCT method.\u003c/p\u003e\u003cp\u003e\u003cb\u003eCell Proliferation, Cycle and Apoptosis Assays\u003c/b\u003e\u003c/p\u003e\u003cp\u003eCell proliferation was detected by MTS assay (Promega) in 96-well plates. For cell cycle analysis, chondrocytes were fixed with 75% ethanol, treated with RNase, stained with PI and analyzed by flow cytometry (Agilent). Apoptosis was assessed using Annexin V-FITC/PI staining (Meilunbio) and flow cytometry. All assays were performed in triplicate.\u003c/p\u003e\u003cp\u003e\u003cb\u003eELISA and Western Blot\u003c/b\u003e\u003c/p\u003e\u003cp\u003eInflammatory cytokine concentrations (IL-1β, IL-6, IL-8, TNF-α) were measured by ELISA kits (Cloud-Clone Corp). For western blot, proteins were extracted with RIPA lysis buffer (Beyotime), separated by SDS-PAGE, transferred to PVDF membranes, and probed with primary antibodies (JAK2, STAT3, MYC, IL-1β, IL-6, IL-8, TNF-α, GAPDH; Proteintech) and HRP-conjugated secondary antibodies (ZSGB). Bands were visualized by ECL (Cell Signaling Technology).\u003c/p\u003e\u003cp\u003e\u003cb\u003ePlasmid Transfection\u003c/b\u003e\u003c/p\u003e\u003cp\u003eCHI3L1 shRNA plasmid (OBiO Technology), JAK2 overexpression vector (OE-JAK2, Genechem), and siRNAs (CHI3L1 siRNA-1/-2/-3, JAK2 siRNA-1/-2/-3, negative control; Hippobio) were transfected into chondrocytes using Lipofectamine 2000 or RNAi MAX (Invitrogen) per manufacturer\u0026rsquo;s protocols.\u003c/p\u003e\u003cp\u003e\u003cb\u003eProtein Microarray\u003c/b\u003e\u003c/p\u003e\u003cp\u003eDifferentially expressed proteins between CHI3L1-treated and control chondrocytes were analyzed using the CSP100 plus chip (Wayen Biotechnologies). Filters: log2∣fold change∣\u0026ge;1.3, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05. KEGG enrichment analysis identified signaling pathways.\u003c/p\u003e\u003cp\u003e\u003cb\u003eRat FJ Degeneration Model\u003c/b\u003e\u003c/p\u003e\u003cp\u003eTwenty-one 4-week-old male Sprague-Dawley rats were randomly divided into sham (n\u0026thinsp;=\u0026thinsp;7), FJ model (n\u0026thinsp;=\u0026thinsp;7), and sh-CHI3L1 (n\u0026thinsp;=\u0026thinsp;7) groups. FJ degeneration was induced by removing the right L4/5 articular processes. sh-CHI3L1 vector (10 \u0026micro;g/5 \u0026micro;L saline) was injected into the left FJ of the sh-CHI3L1 group. Rats were sacrificed at 3 months post-surgery, and left FJ cartilage was collected for HE staining. Animal experiments were approved by the institutional ethics committee.\u003c/p\u003e\u003cp\u003e\u003cb\u003eStatistical Analysis\u003c/b\u003e\u003c/p\u003e\u003cp\u003eData were analyzed using SPSS 25.0. Student\u0026rsquo;s t-test compared two groups, and ANOVA analyzed proliferation curves. Results are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD. P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003eCHI3L1 expression is significantly associated with FJ degeneration\u003c/h2\u003e \u003cp\u003eRT-qPCR results showed significantly higher CHI3L1 mRNA expression in degenerated FJ cartilage compared with normal samples (P\u0026thinsp;=\u0026thinsp;0.0031, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). Moreover, CHI3L1 expression progressively increased with advancing FJ degeneration stages (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). These results suggested that CHI3L1 play important roles in the process of FJ cartilage degeneration.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eCHI3L1 inhibits biological functions of chondrocytes\u003c/h2\u003e \u003cp\u003eRecombinant CHI3L1 significantly suppressed chondrocyte proliferation, with OD490 values decreasing markedly at 72 h and maintaining this downward trend through 120 h(P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA). The effect of CHI3L1 expression on chondrocyte cell cycle was further assessed by flow cytometry. Compared with the control group, G1-phase cell proportion was significantly elevated (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB), indicating that CHI3L1 induced G1-phase arrest. Cell apoptosis investigation indicated the apoptotic rate of chondrocytes treated with CHI3L1 was significantly higher than that observed in the control group (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo further explore the role of CHI3L1 in chondrocytes, three CHI3L1 siRNAs (siRNA-1, 2 and 3) were transfered into cells, with siRNA-3 showing optimal knockdown efficiency by RT-qPCR (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eD). Subsequent assays revealed that CHI3L1 silencing promoted chondrocyte proliferation (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eE), induced G1-to-S phase transition (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eF) and suppressed chondrocyte apoptosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eG).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCHI3L1 promotes expression of inflammatory cytokines\u003c/h3\u003e\n\u003cp\u003eSince inflammation is one of the major causes of FJ degeneration, we explored whether CHI3L1 has effect on the expression of inflammatory cytokines of chondrocytes. After treating with CHI3L1, IL-8 and TNF-α secreted by chondrocytes were significantly increased compared with the control group (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA). Simultaneously, IL-8 and TNF-α secreted by chondrocytes transfected with siRNA-3 were significantly decreased compared with the siRNA-NC control group (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB). These results suggested the potential function of CHI3L1 regulating inflammatory cytokines secretion of chondrocytes. CHI3L1 promoted chondrocytes to express inflammatory cytokines of IL-8 and TNF-α. Whereas, silencing CHI3L1 expression downregulated expression of inflammatory cytokines in chondrocytes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eCHI3L1 regulates expression of inflammatory cytokines through JAK2/STAT3 signaling pathway in chondrocytes\u003c/h3\u003e\n\u003cp\u003eTo clarify the molecular mechanism by which CHI3L1 regulates chondrocyte viability, protein microarray combined with bioinformatics and GO enrichment analyses identified the JAK2/STAT3 signaling pathway as a critical target. Key proteins in this pathway (JAK2, STAT2/STAT3, MYC) were significantly upregulated in CHI3L1-treated chondrocytes (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA), and subsequent validation confirmed marked elevation of P-JAK2, P-STAT3 and MYC protein levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB, F). Besides, western blot further verified ELISA-indicated changes in the protein expression of inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB, F).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo further elucidate whether CHI3L1 regulate expression of inflammatory cytokines through JAK2/STAT3 signaling pathway, we firstly used siRNAs to knockdown expression of JAK2. Results showed that si-JAK2-3 played the highest knockdown efficiency and was then used for all the subsequent experiments (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC). Both the si-NC and si-JAK2-3 transfected chondrocytes were treated with CHI3L1 for 24h. We found that compared with si-NC group, expression of STAT3 and MYC were significantly decreased in chondrocytes transfected with si-JAK2 (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eD, F), indicating that JAK2/STAT3 pathway had been downregulated. Simultaneously, expression of IL-1β, IL-6, IL-8 and TNF-α were also reduced (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eD).\u003c/p\u003e \u003cp\u003eTo rescue JAK2 expression, we constructed an overexpression vector (OE-JAK2) and transfected it into chondrocytes. JAK2 rescue upregulated STAT3 and MYC expression, confirming restoration of the JAK2/STAT3 signaling pathway (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eE, F). Following CHI3L1 treatment, IL-1β, IL-6, IL-8 and TNF-α expression was elevated compared with the si-JAK2 group, yet remained lower than that in the si-NC group (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eE).\u003c/p\u003e \u003cp\u003eCollectively, these results indicate that CHI3L1 regulates inflammatory cytokine expression in chondrocytes primarily via the JAK2/STAT3 signaling pathway.\u003c/p\u003e\n\u003ch3\u003eKnockdown of CHI3L1 inhibits FJ degeneration in vivo\u003c/h3\u003e\n\u003cp\u003eTo further investigate the effect of CHI3L1 on FJ degeneration in vivo, we established L4/5 FJ degenerative rat model. The left L4/5 FJ degeneration model was confirmed to be established successfully through HE staining. The sh-CHI3L1 vector were constructed and injected into the left L4/5 FJ capsule to knockdown CHI3L1 expression in chondrocytes. Comparing HE staining results of FJ cartilage tissues between three groups, we found that in the normal control group, normal facet joint with no joint-space narrowing, normal thickness of articular cartilage, regular cartilage margins, homogeneously distributed chondrocytes, clear boundary line between cartilage and subchondral bone, and no subchondral erosions (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA). In the model group, we found the degenerated FJ with joint-space narrowing, coarse cartilage margins followed by fissuring and flaking, thinning cartilage, blurry boundary line between cartilage and subchondral bone, subchondral erosions, heterogeneously distributed chondrocytes, much more hypertrophic chondrocytes and some necrosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB). Comparing with model group, the sh-CHI3L1 treated group showed attenuate FJ degeneration with clear cartilage margins and boundary line between cartilage and subchondral bone, no cartilage flaking and subchondral erosions, distributed chondrocytes with some hypertrophic chondrocytes but no necrosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eC). The results of suggested that sh-CHI3L1 injection significantly attenuate FJ degeneration in rat.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eFJ cartilage is a tissue composed of chondrocytes that wrapped in a collagen rich extracellular matrix (ECM) they synthesize. FJ cartilage degeneration is caused by multifactorial parameters, including accelerated chondrocyte hypertrophy, excessive production of matrix degrading enzymes such as matrix metallo proteinases (MMPs) and aggrecanases, and increased focal calcification of joint cartilage[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. With onset of cartilage degeneration, chondrocytes undergo multiple changes, in terms of proliferation, viability, hypertrophy and secretory profile including inflammatory cytokines. Eventually, chondrocytes undergo apoptosis and cell death, which leads to destruction of cartilage tissues. Between the series regulatory processes, inflammatory cytokines are highly relevant to the onsets, pathogenesis, and progression of FJ degeneration[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the current study, we investigated the role of CHI3L1 in chondrocytes and FJ cartilage degeneration. CHI3L1, also known as YKL-40, is an inflammatory cytokine that has been reported in multiple researches[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. It plays a major role in tissue injury, inflammation, tissue repair, and remodeling responses. From the clinical FJ cartilage specimens, markedly elevated CHI3L1 expression in degenerative samples aroused our interesting. Wang et al found that CHI3L1 was highly expressed in the degenerated nucleus pulposus tissues[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The level of CHI3L1 in synovial fluid of active knee osteoarthritis patients was significantly higher comparing with age-matched healthy controls. Connor JR et al confirmed that CHI3L1 expression increased in cartilage tissues from patients with osteoarthritic as disease progresses[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Our data showed that CHI3L1 expression was progressively increased with the FJ degeneration stage increased. Taken together, these studies suggest that the inflammatory factor CHI3L1 present an elevated level in cartilage degenerated diseases, and may play an important role in the disease progress.\u003c/p\u003e \u003cp\u003eThe role of CHI3L1 in regulating viability of chondrocytes remains controversial. Recombinant CHI3L1 has been found to reduce the percentage of apoptotic nucleus pulposus cells, and CHI3L1 blocking increase the percentage of apoptotic nucleus pulposus cells[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Johansen JS et al reported that CHI3L1 protein expression is high in cell types characterized by rapid proliferation[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Whereas, Connor JR et al reported that proliferating osteoblasts expressed low to moderate levels of CHI3L1[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Our present study found that, in vitro recombinant CHI3L1 protein significantly inhibited chondrocytes proliferation and cell cycle but promoted apoptosis. Conversely, silencing CHI3L1 expression significantly promoted chondrocytes proliferation and cell cycle, and inhibited apoptosis. Since that different cell types or tissues in different state and development stage were used in these researches, for example, degeneration or normal, early or late development stage, the CHI3L1 may serve as distinct functions on the cell viability. These researches further indicate the complexity of CHI3L1 in regulating cellular biological functions.\u003c/p\u003e \u003cp\u003eCHI3L1 have been found to regulate inflammation in multiple diseases[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. CHI3L1 can stimulate pro-inflammatory mediators and may play a role in type 2 helper cell-mediated inflammation. The levels of pro-inflammatory mediators such as IL-6, IFN-γ, and TNF-α, were found to be correlated with the level of CHI3L1 in rheumatoid arthritis patients. Attur MG et al reported that IL-1β and TNF-α participated in the destruction of articular cartilage matrix by inducing chondrocytes secretion of matrix degrading enzymes[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. G\u0026oacute;mez R et al found that adipokines including leptin and adiponectin can induce the production of pro-inflammatory IL-8 and pro-catabolic MMPs by chondrocytes, and contribute to cartilage damage[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Besides, IL-6, IL-15, IL-17, IL-18 and IL-21 have also been shown to be implicated in osteoarthritis. In our current study, results confirmed that the expression of IL-1β, IL-6, IL-8 and TNF-α were markedly elevated in chondrocytes treated with CHI3L1. Knockdown CHI3L1 expression significantly inhibited the expression of IL-8 and TNF-α. Taken together of these studies, CHI3L1 may contribute to the FJ cartilage degeneration through promoting pro-inflammatory cytokines in chondrocytes.\u003c/p\u003e \u003cp\u003eCHI3L1 has been reported to induce pro-inflammatory molecules through different signaling pathways including NF-κB, TGF-β, and Wnt/β in various pathological process[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Researchers have investigated the biological mechanisms of CHI3L1 in cartilage degenerative diseases. Wang R et al reported that CHI3L1 protected nucleus pulposus via AKT3 signaling during intervertebral disc degeneration[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Jin T et al found that CHI3L1 promotes Staphylococcus aureus-induced osteomyelitis by activating p38/MAPK and Smad signaling pathways[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. In the present study, to further elucidate the molecular mechanism of CHI3L1 in regulating chondrocytes viability and FJ cartilage degeneration, we investigated protein expression microarray. Results confirmed that CHI3L1 promoted chondrocytes to express IL-1β, IL-6, IL-8 and TNF-α through JAK2/STAT3 signaling pathway. Furthermore, in vivo experiments found that knockdown CHI3L1 expression can effectively attenuate FJ cartilage degeneration in rat model. Comprehensively, our research supports that CHI3L1 promote FJ cartilage degeneration through regulating expression of inflammatory cytokines and cell viability of chondrocytes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eBSand BBS designed the research, acquired funding and revised the paper; YZC and ZBQ performed the experiment; LYX, SNC, ZTLand LW collected samples and analyzed clinical data; YZC and ZBQ wrote the paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHartvigsen J, Hancock MJ, Kongsted A, Louw Q, Ferreira ML, Genevay S, Hoy D, Karppinen J, Pransky G, Sieper J, Smeets RJ, Underwood M, Lancet Low Back Pain Series Working G (2018) What low back pain is and why we need to pay attention. 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Somatosens Mot Res 38:339\u0026ndash;346. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1080/08990220.2021.1977267\u003c/span\u003e\u003cspan address=\"10.1080/08990220.2021.1977267\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJin T, He P, Yang R, Geng R, Yang G, Xu Y (2021) CHI3L1 promotes Staphylococcus aureus-induced osteomyelitis by activating p38/MAPK and Smad signaling pathways. Exp Cell Res 403:112596. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.yexcr.2021.112596\u003c/span\u003e\u003cspan address=\"10.1016/j.yexcr.2021.112596\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":" \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cdiv class=\"SimplePara\"\u003eCase information of facet joint degeneration patients\u003c/div\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cdiv class=\"SimplePara\"\u003eDegeneration stage\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cdiv class=\"SimplePara\"\u003en\u003csup\u003ea\u003c/sup\u003e\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eGender\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cdiv class=\"SimplePara\"\u003eAge (years)\u003c/div\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eMale (n\u003csup\u003ea\u003c/sup\u003e)\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eFemale (n\u003csup\u003ea\u003c/sup\u003e)\u003c/div\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eNormal\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e7\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003e3\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cdiv class=\"SimplePara\"\u003e54.86\u0026thinsp;\u0026plusmn;\u0026thinsp;9.58\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eI\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e9\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e6\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003e3\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cdiv class=\"SimplePara\"\u003e55.33\u0026thinsp;\u0026plusmn;\u0026thinsp;9.03\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eII\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e18\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e13\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003e5\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cdiv class=\"SimplePara\"\u003e58.06\u0026thinsp;\u0026plusmn;\u0026thinsp;6.91\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eIII\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e6\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003e2\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cdiv class=\"SimplePara\"\u003e64.67\u0026thinsp;\u0026plusmn;\u0026thinsp;4.19\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003csup\u003ea\u003c/sup\u003e Numbers of cases in each group.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003cbr/\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8782502/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8782502/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose\u003c/strong\u003e:\u0026nbsp;Low back pain (LBP) is a global public health concern closely linked to lumbar facet joint (FJ) degeneration, yet its specific pathogenesis remains unclear. CHI3L1 (chitinase 3 like 1) is involved in inflammation and tissue remodeling, but its role in FJ degeneration is poorly understood. This study aimed to investigate the correlation between CHI3L1 and lumbar FJ degeneration, clarify its regulatory effects on chondrocyte functions, and explore the underlying molecular mechanisms.\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e:\u0026nbsp;Forty human lumbar FJ cartilage tissues were collected to detect CHI3L1 expression via RT-qPCR. In vitro experiments were performed on human chondrocytes treated with recombinant CHI3L1 protein or CHI3L1 siRNA, including cell proliferation, cell cycle, apoptosis, ELISA and western blot. Protein expression microarray was used to identify downstream signaling pathways. In vivo experiments were conducted on FJ degeneration rat models injected with sh-CHI3L1 vector, followed by HE staining for histopathological observation.\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: We found CHI3L1 expression was significantly elevated in degenerated FJ cartilage and positively correlated with degeneration stages. In vitro, CHI3L1 inhibited chondrocyte proliferation, induced G1 phase arrest, promoted apoptosis, and upregulated the expression of inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α). Silencing CHI3L1 reversed these effects. Mechanistically, CHI3L1 regulated inflammatory cytokine expression through activating the JAK2/STAT3 signaling pathway. In vivo, knockdown of CHI3L1 significantly attenuated FJ degeneration in rats.\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: CHI3L1 plays a pivotal role in lumbar FJ degeneration by regulating chondrocyte viability and inflammatory responses via the JAK2/STAT3 signaling pathway. CHI3L1 may serve as a potential biomarker and therapeutic target for FJ degenerative diseases.\u003c/p\u003e","manuscriptTitle":"CHI3L1 regulates chondrocytes function via JAK2/STAT3 signaling pathway during lumbar facet joint degeneration","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-12 10:05:21","doi":"10.21203/rs.3.rs-8782502/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-26T14:16:22+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-26T12:29:14+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-02T08:40:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-29T07:06:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"142487694098080333956350316588802467265","date":"2026-03-25T08:21:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"191175187891859564061279302584939271415","date":"2026-03-25T02:29:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"201427000695310043543364620760705990282","date":"2026-03-24T13:59:55+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-08T19:07:03+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-04T13:26:54+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-04T13:25:50+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Spine Journal","date":"2026-02-04T06:08:48+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a2256b1d-3d8e-427a-9613-874afebbeb09","owner":[],"postedDate":"February 12th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-04-26T14:24:50+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-12 10:05:21","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8782502","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8782502","identity":"rs-8782502","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}