Rheumatoid Synovial Fibroblasts Research Articles

LIGHT regulated gene expression in rheumatoid synovial fibroblasts

BackgroundSynovial hyperplasia caused by rheumatoid arthritis (RA), an autoimmune inflammatory disease, leads to the destruction of the articular cartilage and bone. A member of the tumor necrosis factor superfamily, Lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpes virus entry mediator on T cells (LIGHT) has been shown to correlate with the pathogenesis of RA.MethodsWe used cDNA microarray analysis to compare the expression of genes in rheumatoid fibroblast-like synoviocytes with and without LIGHT stimulation.ResultsSignificant changes in gene expression (P-values < 0.05 and fold change ≥ 2.0) were associated mainly with biological function categories of glycoprotein, glycosylation site as N-linked, plasma membrane part, integral to plasma membrane, intrinsic to plasma membrane, signal, plasma membrane, signal peptide, alternative splicing, and topological domain as extracellular.ConclusionsOur results indicate that LIGHT may regulate the expression in RA-FLS of genes which are important in the differentiation of several cell types and in cellular functions.

Anti-Inflammatory Effects of Cannabigerol in Rheumatoid Arthritis Synovial Fibroblasts and Peripheral Blood Mononuclear Cell Cultures Are Partly Mediated by TRPA1

Since its medical legalization, cannabis preparations containing the major phytocannabinoids (cannabidiol (CBD) and δ9-tetrahydrocannabinol (THC)) have been used by patients with rheumatoid arthritis (RA) to alleviate pain and inflammation. However, minor cannabinoids such as cannabigerol (CBG) also demonstrated anti-inflammatory properties, but due to the lack of studies, they are not widely used. CBG binds several cellular target proteins such as cannabinoid and α2-adrenergic receptors, but it also ligates several members of the transient potential receptor (TRP) family with TRPA1 being the main target. TRPA1 is not only involved in nnociception, but it also protects cells from apoptosis under oxidative stress conditions. Therefore, modulation of TRPA1 signaling by CBG might be used to modulate disease activity in RA as this autoimmune disease is accompanied by oxidative stress and subsequent activation of pro-inflammatory pathways. Rheumatoid synovial fibroblasts (RASF) were stimulated or not with tumor necrosis factor (TNF) for 72 h to induce TRPA1 protein. CBG increased intracellular calcium levels in TNF-stimulated RASF but not unstimulated RASF in a TRPA1-dependent manner. In addition, PoPo3 uptake, a surrogate marker for drug uptake, was enhanced by CBG. RASF cell viability, IL-6 and IL-8 production were decreased by CBG. In peripheral blood mononuclear cell cultures (PBMC) alone or together with RASF, CBG-modulated interleukin (IL)-6, IL-10, TNF and immunoglobulin M and G production which was dependent on activation stimulus (T cell-dependent or independent). However, effects on PBMCs were only partially mediated by TRPA1 as the antagonist A967079 did inhibit some but not all effects of CBG on cytokine production. In contrast, TRPA1 antagonism even enhanced the inhibitory effects of CBG on immunoglobulin production. CBG showed broad anti-inflammatory effects in isolated RASF, PBMC and PBMC/RASF co-cultures. As CBG is non-psychotropic, it might be used as add-on therapy in RA to reduce IL-6 and autoantibody levels.

Glucose as a Potential Key to Fuel Inflammation in Rheumatoid Arthritis.

Glucose is the most important source of energy and homeostasis. Recent investigations are clarifying that glucose metabolism might be altered in rheumatoid arthritis (RA), which would play a role in the inflammatory phenotype of rheumatoid synovial fibroblasts. It may also play a role in a variety of autoimmune diseases’ pathophysiology by modulating immune responses and modifying autoantigen expressions. The research into glucose and its metabolism could lead to a better understanding of how carbohydrates contribute to the occurrence and duration of RA and other autoimmune diseases.

Antcin K Inhibits TNF-α, IL-1β and IL-8 Expression in Synovial Fibroblasts and Ameliorates Cartilage Degradation: Implications for the Treatment of Rheumatoid Arthritis

Extracts from Taiwan’s traditional medicinal mushroom, Antrodia cinnamomea, exhibit anti-inflammatory activities in cellular and preclinical studies. However, this paper is the first to report that Antcin K, a triterpenoid isolated from A. cinnamomea, inhibits proinflammatory cytokine production in human rheumatoid synovial fibroblasts (RASFs), which are major players in rheumatoid arthritis (RA) disease. In our analysis of the mechanism of action, Antcin K inhibited the expression of three cytokines (tumor necrosis factor alpha [TNF-α], interleukin 1 beta [IL-1β] and IL-8) in human RASFs; cytokines that are crucial to RA synovial inflammation. Notably, incubation of RASFs with Antcin K reduced the phosphorylation of the focal adhesion kinase (FAK), phosphoinositide 3-kinase (PI3K), protein kinase B (AKT) and nuclear factor-κB (NF-κB) signaling cascades, all of which promote cytokine production in RA. Intraperitoneal injections of Antcin K (10 mg/kg or 30 mg/kg) attenuated paw swelling, cartilage degradation and bone erosion, and decreased serum levels of TNF-α, IL-1β, IL-8 in collagen-induced arthritis (CIA) mice; in further experiments, IL-6 levels were similarly reduced. The inhibitory effects of Antcin K upon TNF-α, IL-1β and IL-8 expression in human RASFs was achieved through the downregulation of the FAK, PI3K, AKT and NF-κB signaling cascades. Our data support clinical investigations using Antcin K in RA disease.

ICBP90 Regulates MIF Expression, Glucocorticoid Sensitivity, and Apoptosis at the MIF Immune Susceptibility Locus.

Macrophage migration inhibitory factor (MIF) is an inflammatory and neurorendocrine mediator that counterregulates glucocorticoid immunosuppression. MIF polymorphisms, which comprise a variant promoter microsatellite (-794 CATT5-8 ), are linked genetically to autoimmune disease severity and to glucocorticoid resistance. While invasive stimuli increase MIF expression, MIF also is up-regulated by glucocorticoids, which serve as a physiologic regulator of inflammatory responses. This study was undertaken to define interactions between the MIF promoter, the glucocorticoid receptor (GR), and the transcription factor inverted CCAAT box binding protein 90 kd (ICBP90) (also referred to as UHRF1), which binds to the promoter in a -794 CATT5-8 length-dependent manner, to regulate MIF transcription. Interactions of ICBP90, GR, and activator protein 1 (AP-1) with MIF -794 CATT5-8 promoter constructs were assessed by coimmunoprecipitation, Western blotting, and genetic knockdown. Nuclear colocalization studies were performed using anti-transcription factor antibodies and confocal microscopy of glucocorticoid-treated cells. MIF transcription was studied in CEM-C7 T cells, and the impact of the MIF -794 CATT5-8 microsatellite variation confirmed in peripheral blood T cells and in rheumatoid synovial fibroblasts of defined MIF genotype. Functional interactions were quantified by apoptosis and apoptotic signaling in high- and low-genotypic MIF-expressing human cells. We defined functional interactions between the transcription factors ICBP90, the GR, and AP-1 that up-regulated MIF transcription in a -794 CATT5-8 length-dependent manner. Experimental reduction of ICBP90, GR, or AP-1 decreased MIF expression and increased glucocorticoid sensitivity, leading to enhanced apoptosis in T lymphocytes and in rheumatoid synovial fibroblasts. These findings suggest a mechanism for genetic variation of glucocorticoid-regulated MIF transcription, with implications for autoimmune disease severity and glucocorticoid responsiveness.

Activated protein C targets immune cells and rheumatoid synovial fibroblasts to prevent inflammatory arthritis in mice.

To investigate whether activated protein C (APC), a physiological anticoagulant can inhibit the inflammatory/invasive properties of immune cells and rheumatoid arthritis synovial fibroblasts (RASFs) in vitro and prevent inflammatory arthritis in murine antigen-induced arthritis (AIA) and CIA models. RASFs isolated from synovial tissues of patients with RA, human peripheral blood mononuclear cells (PBMCs) and mouse thymus cells were treated with APC or TNF-α/IL-17 and the following assays were performed: RASF proliferation and invasion by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and cell invasion assays, respectively; cytokines and signalling molecules using ELISA or western blot; Th1 and Th17 phenotypes in human PBMCs or mouse thymus cells by flow cytometry. The in vivo effect of APC was evaluated in AIA and CIA models. In vitro, APC inhibited IL-1β, IL-17 and TNF-α production, IL-17-stimulated cell proliferation and invasion and p21 and nuclear factor κB activation in RASFs. In mouse thymus cells and human PBMCs, APC suppressed Th1 and Th17 phenotypes. In vivo, APC inhibited pannus formation, cartilage destruction and arthritis incidence/severity in both CIA and AIA models. In CIA, serum levels of IL-1β, IL-6, IL-17, TNF-α and soluble endothelial protein C receptor were significantly reduced by APC treatment. Blocking endothelial protein C receptor, the specific receptor for APC, abolished the early or preventative effect of APC in AIA. APC prevents the onset and development of arthritis in CIA and AIA models via suppressing inflammation, Th1/Th17 phenotypes and RASF invasion, which is likely mediated via endothelial protein C receptor.

A novel fusion protein attenuates collagen–induced arthritis by targeting interleukin 17A and tumor necrosis factor α

This study was undertaken to generate a novel dual targeting fusion protein (DTF), targeting tumor necrosis factor α (TNF-α) and interleukin 17A (IL-17A), and determine its anti-arthritis properties in vitro and in vivo. DTF consisted of an anti-IL-17A single chain variable fragment, a soluble TNF receptor 1, and an Fc fragment. Both clinical and histopathological evaluations suggest that DTF and etanercept can ameliorate collagen induced arthritis. However, the arthritis severity score of DTF-treated mice was lower than that of etanercept-treated mice. In addition, DTF was more potent than etanercept in decreasing the ratio of RANKL/OPG in the serum and rebalancing the population ratio of Treg/Th17 cells in the spleens. In vitro, IL-17A and TNF-α had synergistic effects in inducing the expression of inflammatory cytokines in fibroblast-like synoviocyte from RA patients (RA-FLS), human leukemia (THP-1), and rheumatoid synovial fibroblast (MH7A). IL-17A and TNF-α also had synergistic effects in inducing proliferation and migration of MH7A cells. However, we observed that DTF was more efficient than etanercept in suppressing these synergistic effects. Our results demonstrate that DTF is highly efficient in the treatment of arthritis and has the potential to overcome the limited therapeutic responses obtained with single cytokine neutralization.

Myostatin Promotes Interleukin-1β Expression in Rheumatoid Arthritis Synovial Fibroblasts through Inhibition of miR-21-5p.

Rheumatoid arthritis (RA) is characterized by the infiltration of a number of pro-inflammatory cytokines into synovial fluid and patients with RA often develop joint destruction and deficits in muscle mass. The growth factor myostatin is a key regulator linking muscle mass and bone structure. We sought to determine whether myostatin regulates rheumatoid synovial fibroblast activity and inflammation in RA. We found that levels of myostatin and interleukin (IL)-1β (a key pro-inflammatory cytokine in RA) in synovial fluid from RA patients were overexpressed and positively correlated. In in vitro investigations, we found that myostatin dose-dependently regulated IL-1β expression through the ERK, JNK, and AP-1 signal-transduction pathways. Computational analysis confirmed that miR-21-5p directly targets the expression of the 3′ untranslated region (3′ UTR) of IL-1β. Treatment of cells with myostatin inhibited miR-21-5p expression and miR-21-5p mimic prevented myostatin-induced enhancement of IL-1β expression, showing an inverse correlation between miR-21-5p and IL-1β expression during myostatin treatment. We also found significantly increased paw swelling in an animal model of collagen-induced arthritis (CIA), compared with controls; immunohistochemistry staining revealed substantially higher levels of myostatin and IL-1β expression in CIA tissue. Our evidence indicates that myostatin regulates IL-1β production. Thus, targeting myostatin may represent a potential therapeutic target for RA.

TNF-\u03b1-induced miR-155 regulates IL-6 signaling in rheumatoid synovial fibroblasts

BackgroundMicroRNAs (miRNAs) are important regulators of a variety of inflammatory mediators. The present study was undertaken to elucidate the role of miRNAs in the rheumatoid cytokine network.MethodsWe analyzed miRNA expression in rheumatoid synovial fibroblasts (RASFs). miRNA array-based screening was used to identify miRNAs differentially expressed between tumor necrosis factor-α (TNF-α)-activated RASFs and untreated RASFs. Transfection of RASFs with miR-155 was used to analyze the function of miR-155. Real-time polymerase chain reaction (PCR) was used to measure the levels of miR-155 in RASFs.ResultsmiRNA microarray analysis revealed that miR-155-5p was the most highly induced miRNA in TNF-α-stimulated RASFs. TNF-α-induced miR-155 expression in RASFs was time-dependent and TNFα dose-dependent, whereas, IL-6 stimulation did not affect miR-155 expression in RASFs. Transfection of miR-155 mimics into RASFs resulted in the decrease JAK2/STAT3 phosphorylation in IL-6-treated RASFs.ConclusionsThe current results demonstrate that TNF-α modulated miRNA expressions in RASFs. Our data showed that miR-155, which is highly induced by TNF-α stimulation, inhibits IL-6-mediated JAK2/STAT3 activation in RASFs. These findings suggest that miR-155 contributes to the cross-regulation between TNF-α and IL-6-mediated inflammatory pathways in RA.

Decoy receptor 3 down-regulates centrosomal protein 70 kDa specifically in rheumatoid synovial fibroblasts

Objectives: Decoy receptor 3 (DcR3) competitively binds to Fas ligand, lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpes virus entry mediator on T cells (LIGHT) and TNF-like ligand 1A (TL1A), thereby preventing their effects. Using a microarray assay, we previously newly identified centrosomal protein 70 kDa (CEP70) as one of the genes whose expression in fibroblast-like synoviocytes from patients with rheumatoid arthritis (RA-FLS) is reduced by DcR3. Here, we investigated the significance of DcR3 regulation of CEP70 for RA-FLS.Methods: Synovial samples were obtained from RA patients who had never been treated with biologics and from osteoarthritis (OA) patients. CEP70 mRNA expression was quantified using RT-qPCR analysis. CEP70 protein expression was assessed using immunohistochemical and western blot analyses.Results: CEP70 was expressed predominantly in the superficial lining layer in RA synovial tissue. CEP70 expression was dose-dependently downregulated by DcR3-Fc in RA-FLS but was not downregulated in OA-FLS. TL1A antibody prevented the DcR3-Fc inhibitory effects on CEP70 expression in RA-FLS.Conclusions: These results indicated that DcR3 reduces CEP70 expression in RA-FLS by binding to membrane-bound TL1A and may suppress RA-FLS proliferation. The reduction in CEP70 expression by DcR3/TL1A signaling may control the hyperplasia of RA synovium.

Disease-Specific Effects of Matrix and Growth Factors on Adhesion and Migration of Rheumatoid Synovial Fibroblasts.

In rheumatoid arthritis (RA), cartilage and bone matrix are degraded, and extracellular matrix (ECM) proteins, acting as cellular activators, are liberated. Similar to ECM proteins, matrix-bound chemokines, cytokines, and growth factors (GFs) influence functional properties of key cells in RA, especially synovial fibroblasts. The role of these molecules on attachment, migration, and proinflammatory and prodestructive activation of RASFs was analyzed. Adhesion/migration of RASFs were examined under GF-enriched (GF+) or -reduced (GF-) conditions with or without addition of matrix-associated GFs, TGF-β, and platelet-derived GF to GF- or culture supernatants. Fibroblast adhesion and alterations in proinflammatory/prodestructive properties (e.g., IL-6/matrix metalloproteinase 3-release) in response to matrix-associated molecules were compared. Effects of GF+, GF-, and other ECM components on human RASF-mediated cartilage invasion were examined in the SCID mouse model. RASF adhesion under GF- conditions was significantly lower compared with GF+ conditions (6.8- versus 8.3-fold). This effect was specific for RA because control cells showed opposite effects (e.g., osteoarthritis synovial fibroblasts [SF]; GF- versus GF+: 10.7- versus 8-fold). Addition of TGF-β to GF- increased RASF attachment (12.7-fold) compared with other matrices and components. RASF adhesion to GF+ matrix resulted in the strongest IL-6 and matrix metalloproteinase-3 release, and was even more pronounced compared with supplementation of single GFs. In vivo, GF- matrix decreased RASF-mediated cartilage invasion compared with GF+ matrix. ECM components and especially GFs when bound within ECM actively enhance RASF attraction and cartilage adhesion. This observation was specific for RASFs as a reverse behavior was observed for controls.

Hypotonic stress promotes ATP release, reactive oxygen species production and cell proliferation via TRPV4 activation in rheumatoid arthritis rat synovial fibroblasts

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune-disease with complex and unclear etiology. Hypotonicity of synovial fluid is a typical characteristic of RA, which may play pivotal roles in RA pathogenesis. In this work, we studied the responses of RA synovial fibroblasts to hypotonic stress in vitro and further explored the underlying mechanisms. Data showed that hyposmotic solutions significantly triggered increases in cytosolic calcium concentration ([Ca2+]c) of synoviocytes. Subsequently, it caused rapid release of ATP, as well as remarkable production of intracellular reactive oxygen species (ROS). Meanwhile, hypotonic stimulus promoted the proliferation of synovial fibroblasts. These effects were almost abolished by calcium-free buffer and significantly inhibited by gadolinium (III) chloride (a mechanosensitive Ca2+ channel blocker) and ruthenium red (a transient receptor potential vanilloid 4 (TRPV4) blocker). 4α-phorbol 12,13-didecanoate, a specific agonist of TRPV4, also mimicked hypotonic shock-induced responses shown above. In contrast, voltage-gated channel inhibitors verapamil and nifedipine had little influences on these responses. Furthermore, RT-PCR and western blotting evidently detected TRPV4 expression at mRNA and protein level in isolated synoviocytes. Taken together, our results indicated that hypotonic stimulus resulted in ATP release, ROS production, and cell proliferation depending on Ca2+ entry through activation of TRPV4 channel in synoviocytes.

Rheumatoid synovial fibroblasts differentiate into distinct subsets in the presence of cytokines and cartilage.

BackgroundWe investigated two distinct synovial fibroblast populations that were located preferentially in the lining or sub-lining layers and defined by their expression of either podoplanin (PDPN) or CD248, and explored their ability to undergo self-assembly and transmigration in vivo.MethodsSynovial fibroblasts (SF) were cultured in vitro and phenotypic changes following stimulation with interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β1 were examined. To examine the phenotype of SF in vivo, a severe combined immunodeficiency (SCID) human-mouse model of cartilage destruction was utilised.ResultsSF in the lining layer in rheumatoid arthritis (RA) expressed high levels of PDPN compared to the normal synovium, whereas CD248 expression was restricted to sub-lining layer cells. TNF-α or IL1 stimulation in vitro resulted in an increased expression of PDPN. In contrast, stimulation with TGF-β1 induced CD248 expression. In the SCID human-mouse model, rheumatoid SF recapitulated the expression of PDPN and CD248. Fibroblasts adjacent to cartilage expressed PDPN, and attached to, invaded, and degraded cartilage. PDPN+ CD248– SF preceded the appearance of PDPN– CD248+ cells in contralateral implants.ConclusionsWe have identified two distinct SF populations identified by expression of either PDPN or CD248 which are located within different anatomical compartments of the inflamed synovial membrane. These markers discriminate between SF subsets with distinct biological properties. As PDPN-expressing cells are associated with early fibroblast migration and cartilage erosion in vivo, we propose that PDPN-expressing cells may be an attractive therapeutic target in RA.

Hyaluronan Oligosaccharides Induce MMP-1 and -3 via Transcriptional Activation of NF-κB and p38 MAPK in Rheumatoid Synovial Fibroblasts.

ObjectiveTo explore the effect of hyaluronan oligosaccharides (HAoligos) on interactions between HA and its principal receptor, CD44, in rheumatoid synovial fibroblasts (RSFs) and matrix metalloproteinase (MMP) production.MethodsRSFs were isolated from rheumatoid synovial tissue. HA distribution was visualized by immunocytochemistry. MMP-1 and MMP-3 induction was analyzed by real-time RT-PCR and immunoblotting. The interaction between HAoligos and their MMP-producing receptors was tested by blocking with anti-CD44 and anti-Toll-like receptor 4 (TLR-4). Phosphorylation of nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) was analyzed by immunoblotting.ResultsEndogenous HA decreased after treatment with HAoligos, while MMP-1 and MMP-3 expression increased in a dose-dependent manner. Pretreatment with anti-CD44 or anti-TLR-4 antibody significantly reduced the effect of HAoligos on MMP-1 and MMP-3 mRNA expression. NF-κB and p38 MAPK phosphorylation was enhanced by HAoligos pretreated with anti-TLR-4, and HAoligo-induced MMP production was blocked with an inhibitor of NF-κB and p38 MAPK pathways.ConclusionsDisruptive changes in CD44-HA interactions by HAoligos enhanced MMP-1 and MMP-3 production via activation of NF-κB and p38 MAPK signaling pathways in RSFs.

Modulation of IL-6 induced RANKL expression in arthritic synovium by a transcription factor SOX5.

Receptor activator of nuclear factor κB ligand (RANKL) is critically involved in bone erosion of rheumatoid arthritis (RA). We previously reported association between younger age at onset of RA and a RANKL promoter SNP that conferred an elevated promoter activity via binding to a transcription factor SOX5. Here we study the regulation of SOX5 levels in relation to RANKL expression in RA synovial fibroblasts (SF) and the development of bone erosion in the collagen-induced arthritis (CIA) mouse. Our data indicated SOX5 levels were higher in synovium and synovial fluid from RA compared to osteoarthritis patients. Pro-inflammatory cytokines upregulated SOX5 and RANKL expression in both primary RA SF and the rheumatoid synovial fibroblast cell line, MH7A. Overexpression of SOX5 resulted in significantly increased RANKL levels, while knockdown of SOX5 resulted in diminished IL-6 mediated RANKL upregulation in MH7A cells. Chromatin immunoprecipitation (ChIP) showed approximately 3-fold enrichment of RANKL-specific DNA in anti-SOX5 immunoprecipitate in IL-6 treated MH7A cells as compared to untreated cells. Locally silencing SOX5 gene significantly diminished RANKL positive cells and bone erosion in CIA mice. These findings suggest SOX5 is an important regulator of IL-6-induced RANKL expression in RA SF.

The growth factor midkine may play a pathophysiological role in rheumatoid arthritis

Objectives: Midkine (MK) is involved in cell proliferation, differentiation, migration, and survival. In this study, we measured serum MK levels in rheumatoid arthritis (RA) and investigated the correlation of serum MK with RA disease activity. Expression and effect of MK in RA synovial tissue were also examined.Methods: Serum MK and production of inflammatory mediators by rheumatoid synovial fibroblasts (RSFs) were measured by enzyme-linked immunosorbent assay. MK expression in synovial tissue was examined by immunohistochemistry. MK receptor expression was analyzed by RT-PCR and Western blotting.Results: RA patients had a significantly higher serum MK level than healthy controls. In RA patients, the MK level was correlated with DAS28-ESR, disability index of the Health Assessment Questionnaire, and rheumatoid factor level. The serum MK level tended to be decreased by anti-TNF therapy. MK was expressed by synovial lining cells in RA synovial tissues and it enhanced the production of IL-6, IL-8, and CCL2 by RSFs. RSFs expressed LDL receptor-related protein 1, candidate receptor for MK.Conclusions: The serum MK level could be a marker of disease activity in RA and an indicator of a poor prognosis. MK may have a role in the pathogenesis of RA via induction of inflammatory mediators.

Interleukin‑12B is upregulated by decoy receptor 3 in rheumatoid synovial fibroblasts.

Decoy receptor 3 (DcR3) competitively binds to three ligands, Fas ligand, lymphotoxin‑related inducible ligand that competes for glycoprotein D binding to herpesvirus entry mediator on T cells and tumor necrosis factor‑like ligand 1A (TL1A), to prevent their effects. Recent studies have suggested that DcR3 directly affects cells as a ligand. Using a microarray assay, our group newly identified interleukin (IL)‑12B, which encodes the p40 subunit common to IL‑12 and IL‑23, as one of the genes for which expression in fibroblast‑like synoviocytes from patients with rheumatoid arthritis (RA‑FLS) is induced by DcR3. The present study demonstrated that IL‑12B mRNA expression was upregulated by DcR3‑Fc in RA‑FLS in a dose‑dependent manner, but not in OA‑FLS. IL‑12B p40 protein in RA‑FLS was increased when stimulated with DcR3‑Fc. Pre‑treatment with anti‑TL1A antibody suppressed the upregulation of IL‑12B mRNA in RA‑FLS stimulated with DcR3‑Fc. DcR3 mRNA expression in RA‑FLS was induced by IL‑23, but not by IL‑12. These results indicated that DcR3 may increase IL‑12 or IL‑23 by inducing IL‑12B p40 expression via membrane‑bound TL1A on RA‑FLS and that IL‑23 reciprocally induces DcR3 expression in RA‑FLS. DcR3 and IL‑23 may interact in a feedback loop that aggravates local inflammation in patients with RA.

Receptor Protein Tyrosine Phosphatase α-Mediated Enhancement of Rheumatoid Synovial Fibroblast Signaling and Promotion of Arthritis in Mice.

During rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) critically promote disease pathogenesis by aggressively invading the extracellular matrix of the joint. The focal adhesion kinase (FAK) signaling pathway is emerging as a contributor to the anomalous behavior of RA FLS. The receptor protein tyrosine phosphatase α (RPTPα), which is encoded by the PTPRA gene, is a key promoter of FAK signaling. The aim of this study was to investigate whether RPTPα mediates FLS aggressiveness and RA pathogenesis. Through RPTPα knockdown, we assessed FLS gene expression by quantitative polymerase chain reaction analysis and enzyme-linked immunosorbent assay, invasion and migration by Transwell assays, survival by annexin V and propidium iodide staining, adhesion and spreading by immunofluorescence microscopy, and activation of signaling pathways by Western blotting of FLS lysates. Arthritis development was examined in RPTPα-knockout (KO) mice using the K/BxN serum-transfer model. The contribution of radiosensitive and radioresistant cells to disease was evaluated by reciprocal bone marrow transplantation. RPTPα was enriched in the RA synovial lining. RPTPα knockdown impaired RA FLS survival, spreading, migration, invasiveness, and responsiveness to platelet-derived growth factor, tumor necrosis factor, and interleukin-1 stimulation. These phenotypes correlated with increased phosphorylation of Src on inhibitory Y(527) and decreased phosphorylation of FAK on stimulatory Y(397) . Treatment of RA FLS with an inhibitor of FAK phenocopied the knockdown of RPTPα. RPTPα-KO mice were protected from arthritis development, which was due to radioresistant cells. By regulating the phosphorylation of Src and FAK, RPTPα mediates proinflammatory and proinvasive signaling in RA FLS, correlating with the promotion of disease in an FLS-dependent model of RA.

Adiponectin Isoforms and Leptin Impact on Rheumatoid Adipose Mesenchymal Stem Cells Function.

Adiponectin and leptin have recently emerged as potential risk factors in rheumatoid arthritis (RA) pathogenesis. In this study we evaluated the effects of adiponectin and leptin on immunomodulatory function of adipose mesenchymal stem cells (ASCs) derived from infrapatellar fat pad of RA patients. ASCs were stimulated with leptin, low molecular weight (LMW) and high/middle molecular weight (HMW/MMW) adiponectin isoforms. The secretory activity of ASCs and their effect on rheumatoid synovial fibroblasts (RA-FLS) and peripheral blood mononuclear cells (PBMCs) from healthy donors have been analysed. RA-ASCs secreted spontaneously TGFβ, IL-6, IL-1Ra, PGE2, IL-8, and VEGF. Secretion of all these factors was considerably upregulated by HMW/MMW adiponectin, but not by LMW adiponectin and leptin. Stimulation with HMW/MMW adiponectin partially abolished proproliferative effect of ASC-derived soluble factors on RA-FLS but did not affect IL-6 secretion in FLS cultures. ASCs pretreated with HMW/MMW adiponectin maintained their anti-inflammatory function towards PBMCs, which was manifested by moderate PBMCs proliferation inhibition and IL-10 secretion induction. We have proved that HMW/MMW adiponectin stimulates secretory potential of rheumatoid ASCs but does not exert strong impact on ASCs function towards RA-FLS and PBMCs.

Tangeretin inhibits IL-1β induced proliferation of rheumatoid synovial fibroblasts and the production of COX-2, PGE2 and MMPs via modulation of p38 MAPK/ERK/JNK pathways

&lt;p&gt;The study aimed to determine the effect of tangeretin in inhibiting the interleukin-1β (IL-1β)-induced proliferation of RASFs and suppression of the production of inflammatory mediators. RASFs were isolated from synovial tissue obtained from patients with RA during knee arthroscopy. The cells were exposed to IL‑1β (1.0 ng/mL) and/ or tangeretin (50 or 100 µM). Cell viability was assessed following treatments. Expressions of MMPs and COX-2 were analysed by real-time PCR and western blotting. Production of prostaglandin E2 (PGE2) by RASFs were analysed by ELISA. Expressions of mitogen activated protein kinases (MAPKs) and nuclear factor-kB (NF-kB) were assessed by western blotting. Tangeretin significantly inhibited the proliferation of RASFs, as well as down-regulated the expression of MMP-1, MMP-3 and COX-2 mRNA and protein and also the phosphorylation of ERK, p38 and JNK. Raised level of expression of NF-κB and PGE2 induced by IL-1β was reduced by tangeretin. Results indicate that tangeretin was effective in inhibiting the synovial fibroblast proliferation, as well regulated MMPs, COX-2, PGE2 via modulation of p38 MAPK, ERK and JNK pathways. &lt;/p&gt;&lt;p&gt; &lt;/p&gt;