Rheumatoid Arthritis Tissue Research Articles

Ferroportin inhibits the proliferation and migration of fibroblast-like synoviocytes in rheumatoid arthritis via regulating ROS/PI3K/AKT signaling pathway.

The aberrant proliferation of fibroblast-like synoviocytes (FLS) significantly contributes to excessive synovial hyperplasia and joint deformity in rheumatoid arthritis (RA). It has been observed that the membrane iron transporter protein, ferroportin (FPN), is commonly downregulated in tumor cells, while its overexpression can inhibit tumor cell proliferation. However, limited studies have investigated the role of iron in the pathogenesis of RA. In this study, we examined the functional relevance of FPN in RA. The expression of FPN in RA tissue specimens and primary cells was assessed using western blotting and RT-PCR. An adjuvant-induced arthritis (AIA) rat model was established to further validate the expression level of FPN. Phenotypic analysis of FLS cell proliferation was performed via CCK-8, clonogenic formation, and cell scratch assays. The involvement of membrane iron transporter proteins was analyzed through RNAseq and reactive oxygen species (ROS) detection. The results demonstrated decreased expression of FPN in the synovial tissue of RA patients compared to the normal group. Overexpression of FPN can inhibit RA-FLS proliferation and migration by suppressing the PI3K/AKT pathway, and this effect is associated with the elevation of ROS levels. Our findings suggest that the downregulation of FPN may contribute to the pathogenesis of RA, indicating a potential role of iron dysregulation in this disease, and FPN regulates the proliferation and migration of FLS by promoting the levels of ROS in FLS as well as suppressing the PI3K/AKT signaling pathway. These results suggest that FPN could be a potential target for alleviating joint damage in RA.

Extracellular vesicles: immunomodulation, diagnosis, and promising therapeutic roles for rheumatoid arthritis.

Extracellular vesicles (EV) can be produced as part of pathology and physiology with increased amounts in pathological conditions. EVs can carry and transfer cargo such as proteins, nucleic acids, and lipids to target cells and mediate intercellular communication resulting in modulation of gene expression, signaling pathways, and phenotype of recipient cells. EVs greatly influence the extracellular environment and the immune response. Their immunomodulatory properties are crucial in rheumatoid arthritis (RA), a condition marked by dysregulated immune response. EVs can modulate the functions of innate and adaptive immune cells in RA pathogenesis. Differentially expressed EV-associated molecules in RA, such as microRNAs (miRNAs), long-noncoding RNAs (lncRNAs), messenger RNAs (mRNAs) and proteins are promising markers to diagnose the disease. miRNA, lncRNA, and circular RNA (circRNA) cargos in EV regulate inflammation and the pathogenic functions of RA fibroblast-like synoviocytes (RA-FLS). Downregulated molecules in RA tissue and drugs can be encapsulated in EVs for RA therapy. This review provides an updated overview of EVs' immunomodulatory, diagnostic, and therapeutic roles, particularly emphasizing mesenchymal stem cell-derived EVs (MSC-EVs).

Engineering M2 macrophage-derived exosomes modulate activated T cell cuproptosis to promote immune tolerance in rheumatoid arthritis

Nanomedicines for immune modulation have made advancements in the treatment of rheumatoid arthritis (RA). However, due to aberrations in patients' immune systems, inducing antigen-specific immune tolerance while halting disease progression remains a significant challenge. Here, we develop a highly targeted multifunctional nanocomplex, termed M2Exo@CuS-CitP-Rapa (M2CPR), with the aim of selectively inhibiting inflammatory immune reactions while promoting immune tolerance towards specific antigens. M2CPR specifically targets inflammatory tissues in RA, delivering CuS NPs, CitP, Rapa, and endogenous anti-inflammatory factors, thereby ameliorating the inflammatory joint microenvironment. CuS NPs induce Cuproptosis of activated T cells, whose fragments are engulfed by resident or recruited macrophages, resulting in abundant production of TGF-β. TGF-β acts synergistically with Rapa to induce the iDCs into tDCs. tDCs present CitP to Naive T cells, promoting Tregs differentiation. Tregs, in turn, produce more TGF-β, inducing tDCs differentiation, thereby establishing a cycle of immune tolerance. Through in vitro and in vivo experiments, we validate that M2CPR can induce robust and durable antigen-specific immune tolerance, offering a new paradigm for RA therapy.

The chromatin landscape of pathogenic transcriptional cell states in rheumatoid arthritis

Synovial tissue inflammation is a hallmark of rheumatoid arthritis (RA). Recent work has identified prominent pathogenic cell states in inflamed RA synovial tissue, such as T peripheral helper cells; however, the epigenetic regulation of these states has yet to be defined. Here, we examine genome-wide open chromatin at single-cell resolution in 30 synovial tissue samples, including 12 samples with transcriptional data in multimodal experiments. We identify 24 chromatin classes and predict their associated transcription factors, including a CD8 + GZMK+ class associated with EOMES and a lining fibroblast class associated with AP-1. By integrating with an RA tissue transcriptional atlas, we propose that these chromatin classes represent ‘superstates’ corresponding to multiple transcriptional cell states. Finally, we demonstrate the utility of this RA tissue chromatin atlas through the associations between disease phenotypes and chromatin class abundance, as well as the nomination of classes mediating the effects of putatively causal RA genetic variants.

Macrophages-mediated delivery of protoporphyrin for sonodynamic therapy of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease characterized by infiltration of inflammatory cells, hyperplasia of synovium, and destruction of the joint cartilage. Owing to the low drug delivery efficiency and limited immunosuppression effect, complete cure for RA remains a formidable challenge. Here, we show that live macrophages (Mφs) carrying protoporphyrin-loaded Fe3O4 nanoparticles can migrate to the RA tissues and inhibit the inflammation by sonodynamic therapy. The inflammation of RA leads to the release of cytokines, which guides the migration of the Mφs into the RA tissues, realizing precise delivery of therapeutics. The following sonodynamic therapy induced by ultrasound and protoporphyrin destructs the proliferating synovial cells and also infiltrated inflammatory cells, demonstrating significant therapeutic effect for RA. Meanwhile, the cytokines and relapse of RA can be remarkably suppressed because of the efficient damage to the resident inflammatory cells.

Identification of PPARG as key gene to link coronary atherosclerosis disease and rheumatoid arthritis via microarray data analysis.

Inflammation is the common pathogenesis of coronary atherosclerosis disease (CAD) and rheumatoid arthritis (RA). Although it is established that RA increases the risk of CAD, the underlining mechanism remained indefinite. This study seeks to explore the molecular mechanisms of RA linked CAD and identify potential target gene for early prediction of CAD in RA patients. The study utilized five raw datasets: GSE55235, GSE55457, GSE12021 for RA patients, and GSE42148 and GSE20680 for CAD patients. Gene Set Enrichment Analysis (GSEA) was used to investigate common signaling pathways associated with RA and CAD. Then, weighted gene co-expression network analysis (WGCNA) was performed on RA and CAD training datasets to identify gene modules related to single-sample GSEA (ssGSEA) scores. Overlapping module genes and differentially expressed genes (DEGs) were considered as co-susceptible genes for both diseases. Three hub genes were screened using a protein-protein interaction (PPI) network analysis via Cytoscape plug-ins. The signaling pathways, immune infiltration, and transcription factors associated with these hub genes were analyzed to explore the underlying mechanism connecting both diseases. Immunohistochemistry and qRT-PCR were conducted to validate the expression of the key candidate gene, PPARG, in macrophages of synovial tissue and arterial walls from RA and CAD patients. The study found that Fc-gamma receptor-mediated endocytosis is a common signaling pathway for both RA and CAD. A total of 25 genes were screened by WGCNA and DEGs, which are involved in inflammation-related ligand-receptor interactions, cytoskeleton, and endocytosis signaling pathways. The principal component analysis(PCA) and support vector machine (SVM) and receiver-operator characteristic (ROC) analysis demonstrate that 25 DEGs can effectively distinguish RA and CAD groups from normal groups. Three hub genes TUBB2A, FKBP5, and PPARG were further identified by the Cytoscape software. Both FKBP5 and PPARG were downregulated in synovial tissue of RA and upregulated in the peripheral blood of CAD patients and differential mRNAexpreesion between normal and disease groups in both diseases were validated by qRT-PCR.Association of PPARG with monocyte was demonstrated across both training and validation datasets in CAD. PPARG expression is observed in control synovial epithelial cells and foamy macrophages of arterial walls, but was decreased in synovial epithelium of RA patients. Its expression in foamy macrophages of atherosclerotic vascular walls exhibits a positive correlation (r = 0.6276, p = 0.0002) with CD68. Our findings suggest that PPARG may serve as a potentially predictive marker for CAD in RA patients, which provides new insights into the molecular mechanism underling RA linked CAD.

Phlorizin Regulates Synovial Hyperplasia and Inflammation in Rats With Rheumatoid Arthritis by Regulating the mTOR Pathway.

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease, and management of it is still a challenge. The present investigation assessed the potential preventive effect of phlorizin on rats with RA. A total of 40 healthy Wistar rats were used for this study. Bovine type II collagen and Freund's incomplete adjuvant (1:1 and 1 mg/ml) were administered on days 1 and 8 of the protocol to induce RA in rats; treatment with phlorizin at 60 or 120 mg/kg was started after the 4th week of the protocol, and its effect on inflammation, level of inflammatory cytokines, and expression of proteins were estimated in RA rats. Moreover, an in vitro study was performed on fibroblast-like synoviocytes (FLSs), and the effects of phlorizin on proliferation, apoptosis, and expression of the mechanistic target of rapamycin kinase pathway protein after stimulating these cells with tumor necrosis factor α (TNF-α) were estimated. The data obtained from the study indicate that phlorizin has the potential to mitigate inflammation and enhance weight management in rats with RA induced by bovine type II collagen (CII). The level of inflammatory cytokines in the serum and the expression of protein kinase B (AKT), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), and mechanistic target of rapamycin kinase (mTOR) proteins in the joint tissue were reduced in phlorizin-treated rats with RA. In this investigation, phlorizin was shown to reverse the histological abnormalities in the joint tissue of rats with RA. The in-vitro study showed that phlorizin reduced proliferation and had no apoptotic effect on TNF-α-stimulated FLSs. Expression of AKT, PI3K, and mTOR proteins was also down-regulated in phlorizin-treated TNF-α-stimulated FLSs. Phlorizin protects against inflammation and reduces injury to synovial tissues in RA by modulating the AKT/PI3K/mTOR pathway.

Blockade of the interleukin-6 signaling pathway in rheumatoid arthritis: Effects on obesity, adipocytokines and glucose metabolism

Interleukin (IL) 6 is one of the key cytokines whose role in the inflammation development in rheumatoid arthritis (RA), is well proven. The pleiotropic effects of the cytokine and biologic agents that inhibit its action have been studied much worse. The review provides information on the effects of IL-6 and blocking its signaling pathway on adipose tissue, glucose metabolism and adipocytokine levels in RA. It has been shown that prolonged blockade of IL-6 receptors does not lead to the adipose tissue accumulation and improves glycemic control, although it is not clear whether such effect is associated only with the anti-inflammatory properties of tocilizumab and sarilumab. Moreover, the mechanism of this beneficial effect is not fully understood, since the data on increased sensitivity of peripheral tissues to insulin during tocilizumab treatment are ambiguous. Perhaps changes in the relationship of adipocytokines or hormones play a certain role.

Adipokines in Rheumatoid Arthritis: Emerging Biomarkers and Therapeutic Targets.

Rheumatoid arthritis (RA) is a chronic inflammatory disease manifested by joint involvement, extra-articular manifestations, and general symptoms. Adipose tissue, previously perceived as an inert energy storage organ, has been recognised as a significant contributor to RA pathophysiology. Adipokines modulate immune responses, inflammation, and metabolic pathways in RA. Although most adipokines have a pro-inflammatory and aggravating effect on RA, some could counteract this pathological process. The coexistence of RA and sarcopenic obesity (SO) has gained attention due to its impact on disease severity and outcomes. Sarcopenic obesity further contributes to the inflammatory milieu and metabolic disturbances. Recent research has highlighted the intricate crosstalk between adipose tissue and skeletal muscle, suggesting potential interactions between these tissues in RA. This review summarizes the roles of adipokines in RA, particularly in inflammation, immune modulation, and joint destruction. In addition, it explores the emerging role of adipomyokines, specifically irisin and myostatin, in the pathogenesis of RA and their potential as therapeutic targets. We discuss the therapeutic implications of targeting adipokines and adipomyokines in RA management and highlight the challenges and future directions for research in this field.

GelMA Hydrogel as a Promising Delivery System for Osthole in the Treatment of Rheumatoid Arthritis: Targeting the miR-1224-3p/AGO1 Axis.

Rheumatoid arthritis (RA) is a multifaceted, chronic, progressive autoimmune disease. This study aims to explore the potential benefits of an enhanced drug delivery system utilizing optimized Gelatin Methacryloyl (GelMA) vectors in RA management. We evaluated the levels of miR-1124-3p and AGO1 in RA tissues and cell lines using qPCR, WB, and immunofluorescence. The effects of osthole on inflammatory response and joint morphology were determined by qPCR, H&E staining, and micro-CT. The data showed that miR-1224-3p was downregulated in RA tissues and HUM-iCell-s010RA cells, while the overexpression of miR-1224-3p in HUM-iCell-s010RA cells reduced the expression of IL-6 and IL-1β. Luciferase assay demonstrated that AGO1 was a direct target gene of miR-1224-3p. Additionally, osthole treatment increased miR-1224-3p levels and decreased AGO1 expression. The release data showed that osthole loaded on GelMA was released at a slower rate than free osthole. Further studies in a mouse model of CIA confirmed that osthole-loaded GelMA was more effective in attenuating osteopenia in RA as well as alleviating autoimmune arthritis. These findings suggest that osthole can regulate the miR-1224-3p/AGO1 axis in RASFs cells and has the potential to be developed as a clinical anti-RA drug. GelMA could provide a new approach to long-term RA treatment.

Aberrant pro-inflammatory responses of CD20+ T cells in experimental arthritis

CD20+ T cells comprise a highly inflammatory subset implicated in autoimmunity, including rheumatoid arthritis (RA). We sought to characterize the CD20+ T cell subset in the murine collagen-induced arthritis (CIA) model of RA and investigate the phenotype and functional relevance of CD3+CD20+ T cells in the lymph nodes and arthritic joints using flow cytometry and immunohistochemistry. We demonstrate that CD3+CD4+CD20+ and CD3+CD8+CD20+ T cells are expanded in the draining lymph nodes of CIA mice, produce increased levels of pro-inflammatory cytokines and are less susceptible to regulation by regulatory T cells. Notably, CD3+CD4+CD20+ and CD3+CD8+CD20+ T cells are enriched with CXCR5+PD-1+ T follicular helper cells and CXCR5-PD-1+ peripheral T helper cells, subsets of T cells implicated in promoting B-cell responses and antibody production within pathologically inflamed non-lymphoid tissues in RA. Our findings suggest CD20+ T cells are associated with inflammatory responses and may exacerbate pathology by promoting inflammatory B-cell responses.

Anti-proliferation and anti-migration effects of Yishen Tongbi decoction in experimental rheumatoid arthritis by suppressing SLC3A2/integrin β3 signaling pathways

BackgroundYishen Tongbi (YSTB) decoction is a patented herbal formula that is used in China to treat rheumatoid arthritis (RA); however, the exact mechanism of its anti-synovial hyperplasia efficacy has not been fully elucidated. PurposeBased on our previous proteomics study, we aimed to reveal whether YSTB inhibits the proliferation and migration of RA-FLSs through the SLC3A2/integrin β3 pathway in vivo and in vitro. Study designThe study design consists of three parts, a comparison of the expression of SLC3A2 and integrin β3 in synovial tissues of RA and OA patients; an animal experiment to verify the pharmacodynamic effect of YSTB, and in vitro experiment to elucidate the specific mechanism of YSTB. MethodsThe expression of SLC3A2 and integrin β3 in the synovial tissues of patients with RA and osteoarthritis (OA) patients were detected by immunohistochemistry (IHC). In vitro, firstly, the proliferation and migration abilities of HFLS (human fibroblast-like synoviocytes) and HFLS-RA (human fibroblast-like synoviocytes-RA) cells were compared by EdU staining and wound healing assays, respectively, and the differences in the expression and localization of SLC3A2, integrin β3, p-FAK and p-Src between HFLS and HFLS-RA cells were detected by IF and WB. In vivo, DBA/1 mice were injected with bovine collagen II to construct a CIA mouse model. Paw swelling, body weight and the arthritis index (AI) were used as basic treatment evaluation indicators for YSTB. Micro-CT and histopathological analyses of the knee and ankle joints were also performed. In addition, the expression of SLC3A2, integrin β3, p-FAK and p-Src in the synovial tissue of mice was detected by IHC. Subsequently, CCK-8 was used to screen for suitable concentrations of YSTB for use in HFLS-RA cells. EdU staining and transwell migration assays were performed to evaluate the inhibitory effect of YSTB on cell proliferation and migration, and WB was conducted to assess whether YSTB inhibited HFLS-RA migration through downregulation of the SLC3A2/integrin β3 pathways. ResultsIHC showed that the expression of SLC3A2 and integrin β3 was higher in RA synovial tissues than in OA tissues. In vivo experiments showed that YSTB inhibited synovial hyperplasia, prevented bone destruction, and reduced the expression of SLC3A2, integrin β3, p-FAK and p-Src. In vitro experiments showed that YSTB inhibited HFLS-RA migration and proliferation by inhibiting the expression of SLC3A2/integrin β3 and downstream signaling molecules. ConclusionYSTB inhibits the proliferation and migration of synovial fibroblasts in RA by downregulating the SLC3A2/integrin β3 pathways.

Chemokines and chemokine receptors as promising targets in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease that commonly causes inflammation and bone destruction in multiple joints. Inflammatory cytokines, such as IL-6 and TNF-α, play important roles in RA development and pathogenesis. Biological therapies targeting these cytokines have revolutionized RA therapy. However, approximately 50% of the patients are non-responders to these therapies. Therefore, there is an ongoing need to identify new therapeutic targets and therapies for patients with RA. In this review, we focus on the pathogenic roles of chemokines and their G-protein-coupled receptors (GPCRs) in RA. Inflamed tissues in RA, such as the synovium, highly express various chemokines to promote leukocyte migration, tightly controlled by chemokine ligand-receptor interactions. Because the inhibition of these signaling pathways results in inflammatory response regulation, chemokines and their receptors could be promising targets for RA therapy. The blockade of various chemokines and/or their receptors has yielded prospective results in preclinical trials using animal models of inflammatory arthritis. However, some of these strategies have failed in clinical trials. Nonetheless, some blockades showed promising results in early-phase clinical trials, suggesting that chemokine ligand-receptor interactions remain a promising therapeutic target for RA and other autoimmune diseases.

Ubiquitin D promotes the progression of rheumatoid arthritis via activation of the p38 MAPK pathway.

Ubiquitin D (UBD), a member of the ubiquitin‑like modifier family, has been reported to be highly expressed in various types of cancer and its overexpression is positively associated with tumor progression. However, the role and mechanism of UBD in rheumatoid arthritis (RA) remain elusive. In the present study, the gene expression profiles of GSE55457 were downloaded from the Gene Expression Omnibus database to assess differentially expressed genes and perform functional enrichment analyses. UBD was overexpressed by lentivirus transfection. The protein level of UBD, p‑p38 and p38 in RA‑fibroblast‑like synoviocytes (FLSs) were examined by western blotting. Cell Counting Kit‑8 and flow cytometry assays were used to detect the functional changes of RA‑FLSs transfected with UBD and MAPK inhibitor SB202190. The concentrations of inflammatory factors (IL‑2, IL‑6, IL‑10 and TNF‑α) were evaluated using ELISA kits. The results revealed that UBD was overexpressed in RA tissues compared with in the healthy control tissues. Functionally, UBD significantly accelerated the viability and proliferation of RA‑FLSs, whereas it inhibited their apoptosis. Furthermore, UBD significantly promoted the secretion of inflammatory factors (IL‑2, IL‑6, IL‑10 and TNF‑α). Mechanistically, elevated UBD activated phospohorylated‑p38 in RA‑FLSs. By contrast, UBD overexpression and treatment with the p38 MAPK inhibitor SB202190 not only partially relieved the UBD‑dependent effects on cell viability and proliferation, but also reversed its inhibitory effects on cell apoptosis. Furthermore, SB202190 partially inhibited the effects of UBD overexpression on the enhanced secretion of inflammatory factors. The present study indicated that UBD may mediate the activation of p38 MAPK, thereby facilitating the proliferation of RA‑FLSs and ultimately promoting the progression of RA. Therefore, UBD may be considered a potential therapeutic target and a promising prognostic biomarker for RA.

MiR-30e-5p deficiency exerts an inhibitory effect on inflammation in rheumatoid arthritis via regulating Atl2 expression.

This study aims to investigate the inflammatory effect of the microRNA (miRNA) miR-30e-5p on rheumatoid arthritis (RA) development in RA mice and fibroblast-like synoviocytes (FLS). MiR-30e-5p and atlastin GTPase 2 (Atl2) expression in RA tissues and RA-FLS was evaluated using real-time quantitative polymerase chain reaction. The function of miR-30e-5p in inflammation of RA mice and RA-FLS was analyzed by enzyme-linked immunosorbent assay (ELISA) and Western blotting. 5-ethynyl-2'-deoxyuridine (EdU) assay was used to detect RA-FLS proliferation. Luciferase reporter assay was to confirm the interaction between miR-30e-5p and Atl2. MiR-30e-5p expression was upregulated in the tissues from RA mice. Silencing miR-30e-5p alleviated inflammation in RA mice and RA-FLS. MiR-30e-5p negatively modulated Atl2 expression. Atl2 knockdown exerted a proinflammatory effect on RA-FLS. Atl2 knockdown rescued the inhibitory effect of miR-30e-5p knockdown on proliferation and inflammatory response of RA-FLS. MiR-30e-5p knockdown inhibited the inflammatory response in RA mice and RA-FLS through Atl2.

Protein arginine methyltransferase 1 upregulates matrix metalloproteinase-2/9 expression via Zeste Homolog 2 to promote human rheumatoid arthritis fibroblast-like synovial cell survival and metastasis.

To explore the role of protein arginine methyltransferase 1 (PRMT1) in the development of rheumatoid arthritis (RA). Fibroblast-like synoviocytes (FLS) were isolated from synovial tissues, cultured and transfected with plasmid vector or short hairpin RNA (shRNA). The morphology and surface markers of FLS were investigated by light microscopy and flow cytometry. The expression levels of PRMT1, Zeste Homolog 2 (EZH2), matrix metalloproteinase-2 (MMP-2) and MMP-9 were detected by real-time polymerase chain reaction and Western blotting. Cell viability was tested by MTT assay, cell proliferation was assessed by EdU assay, cell invasion was evaluated by Transwell invasion test, cell migration was detected by wound healing assay, and cell apoptosis was detected by flow cytometry. The expression of PRMT1 was elevated in RA synovial tissues compared with control tissues. FLS from control tissues showed a lower level of PRMT1 than FLS from RA tissues, and FLS from RA tissues had a stronger ability of cell survival and metastasis than those from control tissues. When silencing PRMT1 expression, FLS from RA tissues showed a decreased ability of cell survival and metastasis. Additionally, FLS from RA tissues expressed a higher level of MMP-2 and MMP-9. When silencing PRMT1 expression, the expression of MMP-2 and MMP-9 of FLS was suppressed. Furthermore, the effect of PRMT1 on FLS was mediated by EZH2. We found that PRMT1 had an overall effect on FLS via EZH2, which contributed to the development of RA. Hence, PRMT1 and EZH2 provide potential targets for RA treatment.

Sonic hedgehog promotes synovial inflammation and articular damage through p38 mitogen-activated protein kinase signaling in experimental arthritis

Activated fibroblast-like synoviocytes (FLS) play a pivotal role in synovial inflammation and joint destruction of rheumatoid arthritis (RA). The mechanisms by which sonic hedgehog (SHH) signaling promotes RA FLS-mediated chronic inflammation and tissue damage are not fully understood. The present study aims to determine the role of SHH signaling in the pathogenesis of RA and to explore the potential mechanism(s). We found that the components of SHH signaling were highly expressed in FLS and synovial tissue from patients with RA and in the joint tissue of collagen-induced arthritis (CIA) mice. Overexpression of SHH aggravated the synovial inflammation and joint destruction of CIA and exacerbated cartilage degradation in the cartilage and RA FLS-engrafted severe combined immunodeficiency (SCID) model. Conversely, inhibition of SHH signaling significantly alleviated arthritis severity and reduced cartilage destruction caused by the invasion of RA FLS in vivo. Moreover, we found that p38 mitogen-activated protein kinase (MAPK) cascade was regulated by SHH signaling in RA FLS and the level of phospho-p38 in the joint tissue of CIA was decreased after blockade of SHH signaling. Inhibition of p38 MAPK abolished the effect of SHH overexpression on synovial inflammation and articular destruction of CIA and suppressed the aggressive properties of RA FLS, which were promoted by SHH agonist. In conclusion, our study suggests that SHH signaling aggravates synovial inflammation and joint destruction of experimental arthritis and promotes the abnormal behavior of RA FLS in a p38-dependent manner. SHH-p38 MAPK signaling could be a potential target for the treatment of RA.

MicroRNA-211-5p Overexpression Effect on Endoplasmic Reticulum Stress and Apoptotic Genes in Fibroblast-like Synoviocytes of Rheumatoid Arthritis.

Fibroblast-like synoviocytes (FLSs) play a major role in the pathogenesis of rheumatoid arthritis (RA). Endoplasmic reticulum (ER) stress and dysregulation of unfolded protein response are involved in the resistance to apoptosis of FLSs in RA (RA-FLSs). MicroRNA (MiR)-211 plays an important role in controlling ER stress and apoptotic genes in a PKR-like ER kinase (PERK)-activating transcription factor 4 (ATF4)-dependent manner. We investigated the effect of miR-211-5p overexpression on ER stress and apoptotic genes in RA-FLSs. FLSs were isolated from synovial tissues of trauma (n=10) and RA (n=10) patients. MiR-211-5p and mRNA expression of the selected genes involved in the PERK pathway and apoptosis regulation were measured in RA, trauma, and thapsigargin (Tg)-treated RA-FLSs. Afterward, Tg-treated RA-FLSs following miR-211-5p overexpression were evaluated for miR-211-5p and mRNA levels of the study genes. The expression of miR-211-5p, PERK, BAX, and BCL2 showed no differences between RA and trauma. However, the expression of ATF4 and BCL-XL showed a significant increase in trauma. In addition, the levels of C/EBP homologous protein (CHOP) and MCL1 indicated a significant increase in RA-FLSs. Tg treatment significantly increased the expression of PERK, ATF4, and CHOP in RA-FLSs with no effect on miR-211-5p, BAX, BCL2, BCL-XL, and MCL1. Furthermore, Tg treatment following miR-211-5p overexpression in RA-FLSs showed a significant increase in levels of miR-211-5p with no changes in apoptotic genes. MiR-211-5p overexpression in stimulated RA-FLSs did not alter the levels of selected genes involved in apoptosis regulation. However, more investigations are necessary to determine the ER stress role in apoptosis regulation in RA-FLSs.

Elevated expression of TAM receptor tyrosine kinase in synovial fluid and synovial tissue of rheumatoid arthritis.

To investigate the expression and roles of TAM (Tyro3/Axl/Mer) receptor tyrosine kinases (TK) in synovial fluid and synovial tissue of patients with rheumatoid arthritis (RA). The expression of TAM TKs in the synovial fluid and synovial tissues of RA and osteoarthritis (OA) patients was measured by ELISA and immunohistochemistry. The relationships between soluble TAM TKs (sTAM TKs) levels and the clinical features, laboratory parameters and disease activity were analyzed in RA. The concentrations of sTAM TK in the synovial fluids of RA patients were increased in comparison to those of OA patients. Compared with OA patients, the expression of membrane Tyro3 TK (mTyro3 TK) and mMer TK in RA patient synovial tissue were significantly increased, which may partly explain the possible mechanism of elevated levels of sTAM TK in RA patient synovial fluid. sAxl TK levels were decreased in RA patients under sulfasalazine treatment and elevated in patients under Iguratimod treatment. Furthermore, sTyro3 TK levels were positively correlated with erythrocyte sedimentation rate (ESR) and negatively correlated with white blood cells (WBCs), red blood cells (RBCs), and hemoglobin (HB) in RA patients. The levels of sMer TK were positively associated with disease duration and rheumatoid factor (RF) and negatively correlated with HB, complement 3 (C3), and C4. Taken together, TAM TKs might be involved in RA synovial tissue inflammation.

Circ_0088194 Regulates Proliferation, Migration, Apoptosis, and Inflammation by miR-30a-3p/ADAM10 Axis in Rheumatoid Arthritis Fibroblastic Synovial Cells.

Dysregulation of circular RNAs (circRNAs) has been observed in multiple diseases including rheumatoid arthritis (RA), and we investigated the role of the circ_0088194/microRNA (miR)-30a-3p/a disintegrin and metalloproteinase 10 (ADAM10) axis in RA. Circ_0088194, miR-30a-3p, and ADAM10 contents in RA tissues and RA-fibroblast-like synoviocytes (RA-FLSs) were analyzed by real-time quantitative polymerase chain reaction (RT-qPCR) and western blot. Cell proliferation, migration, apoptosis, and inflammatory factor secretion of RA-FLSs were detected using 5-ethynyl-2'-deoxyuridine (EdU), wound healing assay, flow cytometry, and enzyme-linked immunosorbent assay (ELISA). Targeting relationship between miR-30a-3p and circ_0088194 or ADAM10 was validated by luciferase reporter system, RNA immunoprecipitation (RIP), and RNA pull-down assays. Circ_0088194 and ADAM10 levels were increased, while miR-30a-3p was decreased in RA tissues and RA-FLSs. Circ_0088194 knockdown suppressed the growth, migration, and inflammation of RA-FLSs, while the upregulation of circ_0088194 showed opposite effects. Circ_0088194 directly targeted miR-30a-3p, ADAM10 was a target of miR-30a-3p, and circ_0088194 regulated the expression of ADAM10 by sponging miR-30a-3p. MiR-30a-3p inhibition restored the inhibition effects of circ_0088194 knockdown or RA-FLSs. Moreover, miR-30a-3p re-expression repressed growth, migration, and inflammatory response in RA-FLSs, which were reversed by ADAM10 overexpression. Circ_0088194 acted on miR-30a-3p/ADAM10 axis to promote the proliferation, migration, and inflammatory response, and inhibit apoptosis in RA-FLSs.