Rheumatoid Synoviocytes Research Articles

Expression profiling of genes in rheumatoid fibroblast-like synoviocytes regulated by tumor necrosis factor-like ligand 1A using cDNA microarray analysis.

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation in synovial tissues. Hyperplasia of synovial tissue leads to the formation of pannus, which invades joint cartilage and bone resulting in joint destruction. Tumor necrosis factor-like ligand 1A (TL1A), a member of the tumor necrosis factor superfamily (TNFSF15), contributes to the pathogenesis of autoimmune diseases, including RA. In the present study, a cDNA microarray was used to search for genes whose expression in rheumatoid fibroblast-like synoviocytes (RA-FLS) were regulated by TL1A. Four individual lines of primary cultured RA-FLS were incubated either with recombinant human TL1A protein or phosphate-buffered saline, as an unstimulated control, for 12 h. Gene expression was then detected through the microarray assay. The results revealed the expression profiles of genes in RA-FLS regulated by TL1A. The present study also demonstrated the functions of those genes whose expression in RA-FLS was regulated by TL1A. Among the genes in this profile, the present study focused on the following genes: Spectrin repeat-containing nuclear envelope 1, Fc receptor-like 2, PYD (pyrin domain)-containing 1, cell division cycle 45 homolog, signal transducer and activator of transcription 5B, and interferon regulatory factor 4. These genes may affect the pathogenesis of RA, including proliferation, regulation of B cells and T cells, inflammation, and cytokine processing. The present study revealed for the first time, to the best of our knowledge, the expression profile of genes in RA-FLS regulated by TL1A. The data indicate that TL1A may regulate the gene expression of various key molecules in RA-FLS, thus affecting the pathogenesis of RA. Further investigations of the genes detected in the current profiles may provide a deeper understanding of the pathogenesis and a novel target for the treatment of RA.

Salvianolic acid B remits LPS-induced injury by up-regulating miR-142-3p in MH7A cells

BackgroundRheumatoid arthritis (RA) is a common inflammatory disease, which significantly reduces the quality of life and increases the risk of cardiovascular and cerebrovascular diseases. The present work studied the therapeutic potency of Salvianolic acid B (Sal-B) for RA and revealed one of the possible underlying mechanisms. MethodsHuman rheumatoid fibroblast-like synoviocytes (MH7 A) were treated with Sal-B before, during or after lipopolysaccharide (LPS) stimulation. CCK-8 assay, Annexin V-FITC/PI double-staining, RT-qPCR, Western blotting and ELISA were carried out to measure the changes of cell viability, apoptosis, and the release of pro-inflammatory cytokines. Next, the involvement of miR-142-3p and related signaling pathways in Sal-B-mediated protection was studied. ResultsSal-B (10 μM) treatment significantly ameliorated LPS injury to MH7 A cells, as cell viability was increased, expression of p53 and p21 was repressed, apoptosis was inhibited, and the release of MCP-1, IL-6 and TNF-α was reduced. However, Sal-B (10 μM) treated alone has no impacts on MH7 A cells in the abovementioned aspects. miR-142-3p was down-regulated by LPS stimulation, while was up-regulated by treatment of Sal-B. Rescue assay results showed that Sal-B did not remit LPS injury when miR-142-3p was silenced. And also, the inhibitory effects of Sal-B on NF-κB and JNK pathways were abolished by miR-142-3p silence. ConclusionSal-B could protect against and reverse LPS-induced injury in MH7 A cells, showing anti-apoptotic and anti-inflammatory capacities. The anti-RA potential of Sal-B might be via up-regulating miR-142-3p, and subsequently modulating NF-κB and JNK pathways.

PTPN14 phosphatase and YAP promote TGFβ signalling in rheumatoid synoviocytes

ObjectiveWe aimed to understand the role of the tyrosine phosphatase PTPN14—which in cancer cells modulates the Hippo pathway by retaining YAP in the cytosol—in fibroblast-like synoviocytes (FLS) from patients with...

Melatonin attenuates TNF-α and IL-1β expression in synovial fibroblasts and diminishes cartilage degradation: Implications for the treatment of rheumatoid arthritis.

The hormone melatonin has many properties, including antioxidant, anti-inflammatory, and immunomodulatory effects. Melatonin has been demonstrated to be beneficial in several inflammatory autoimmune diseases, but its effects in rheumatoid arthritis (RA) remain controversial. We sought to determine how melatonin regulates inflammation in RA. We found that melatonin dose-dependently inhibits tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β expression through the PI3K/AKT, ERK, and NF-κB signaling pathways. We also identified that melatonin inhibits TNF-α and IL-1β production by upregulating miR-3150a-3p expression. Synovial tissue specimens from RA patients and culture of human rheumatoid fibroblast-like synoviocytes confirmed that the MT1 receptor is needed for the anti-inflammatory activities of melatonin. Importantly, melatonin also significantly reduced paw swelling, cartilage degradation, and bone erosion in the collagen-induced arthritis mouse model. Our results indicate that melatonin ameliorates RA by inhibiting TNF-α and IL-1β production through downregulation of the PI3K/AKT, ERK, NF-κB signaling pathways, as well as miR-3150a-3p overexpression. The role of melatonin as an adjuvant treatment in patients with RA deserves further clinical studies.

Curculigoside exerts significant anti‑arthritic effects invivo and invitro via regulation of the JAK/STAT/NF‑κB signaling pathway.

The present study aimed to investigate the anti-arthritic effects of curculigoside isolated from the rhizome of Curculigo orchioides Gaertn in vivo and in vitro, as well as to determine the potential underlying mechanisms. A rat model of arthritis was induced with type II collagen. Arthritic rats were treated with curculigoside (50 mg/kg) and blood samples were collected to determine serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-10, IL-12 and IL-17A. Furthermore, indices of the thymus and spleen were determined. The anti-proliferative effects of curculigoside were detected with Cell Counting kit-8 assays in rheumatoid arthritis-derived fibroblast-like synoviocyte MH7A cells. In addition, expression levels of Janus kinase (JAK)1, JAK3, signal transducer and activator of transcription (STAT)3, nuclear factor (NF)-κB p65 and its inhibitor (IκB) were determined by western blotting. The results revealed that curculigoside inhibited paw swelling and arthritis scores in type II collagen-induced arthritic (CIA) rats. Additionally, curculigoside decreased serum levels of TNF-α, IL-1β, IL-6, IL-10, IL-12 and IL-17A in CIA rats. Curculigoside also significantly inhibited MH7A cell proliferation in a time and concentration-dependent manner. Furthermore, treatment downregulated the expression of JAK1, JAK3 and STAT3, and upregulated cytosolic nuclear factor (NF)-κB p65 and IκB. In conclusion, the results of the present study indicated that curculigoside exhibited significant anti-arthritic effects in vivo and in vitro, and the molecular mechanism may be associated with the JAK/STAT/NF-κB signaling pathway.

Long noncoding RNA LERFS negatively regulates rheumatoid synovial aggression and proliferation

Fibroblast-like synoviocytes (FLSs) are critical to synovial aggression and joint destruction in rheumatoid arthritis (RA). The role of long noncoding RNAs (lncRNAs) in RA is largely unknown. Here, we identified a lncRNA, LERFS (lowly expressed in rheumatoid fibroblast-like synoviocytes), that negatively regulates the migration, invasion, and proliferation of FLSs through interaction with heterogeneous nuclear ribonucleoprotein Q (hnRNP Q). Under healthy conditions, by binding to the mRNA of RhoA, Rac1, and CDC42 - the small GTPase proteins that control the motility and proliferation of FLSs - the LERFS-hnRNP Q complex decreased the stability or translation of target mRNAs and downregulated their protein levels. But in RA FLSs, decreased LERFS levels induced a reduction of the LERFS-hnRNP Q complex, which reduced the binding of hnRNP Q to target mRNA and therefore increased the stability or translation of target mRNA. These findings suggest that a decrease in synovial LERFS may contribute to synovial aggression and joint destruction in RA and that targeting the lncRNA LERFS may have therapeutic potential in patients with RA.

Glycogen Metabolism and Rheumatoid Arthritis: The Role of Glycogen Synthase 1 in Regulation of Synovial Inflammation via Blocking AMP-Activated Protein Kinase Activation.

To investigate the role of glycogen metabolism in regulating rheumatoid fibroblast-like synoviocyte (FLS)-mediated synovial inflammation and its underlying mechanism. FLSs were separated from synovial tissues (STs) obtained from rheumatoid arthritis (RA) patients. Glycogen content was determined by periodic acid Schiff staining. Protein expression was analyzed by Western blot or immunohistochemistry. Gene expression of cytokines and matrix metalloproteinases (MMPs) was evaluated by quantitative real-time PCR. FLS proliferation was detected by EdU incorporation. Migration and invasion were measured by Boyden chamber assay. Glycogen levels and glycogen synthase 1 (GYS1) expression were significantly increased in the ST and FLSs of RA patients. TNF-α or hypoxia induced GYS1 expression and glycogen synthesis in RA FLSs. GYS1 knockdown by shRNA decreased the expression of IL-1β, IL-6, CCL-2, MMP-1, and MMP-9 and proliferation and migration by increasing AMP-activated protein kinase (AMPK) activity in RA FLS. AMPK inhibitor or knockdown AMPK could reverse the inhibitory effect of GYS1 knockdown on the inflammatory response in RA FLSs; however, an AMPK agonist blocked RA FLS activity. We further determined that hypoxia-inducible factor-1α mediates TNF-α- or hypoxia-induced GYS1 expression and glycogen levels. Local joint depletion of GYS1 or intraperitoneal administration with an AMPK agonist ameliorated the severity of arthritis in rats with collagen-induced arthritis. Our data demonstrate that GYS1-mediated glycogen accumulation contributes to FLS-mediated synovial inflammation in RA by blocking AMPK activation. In our knowledge, this is a first study linking glycogen metabolism to chronic inflammation. Inhibition of GYS1 might be a novel therapeutic strategy for chronic inflammatory arthritis, including RA.

Transcription Factor NFAT5 Promotes Migration and Invasion of Rheumatoid Synoviocytes via Coagulation Factor III and CCL2.

Fibroblast-like synoviocytes (FLSs) play a key role in the progression of rheumatoid arthritis (RA) as a primary component of invasive hypertrophied pannus. FLSs of RA patients (RA-FLSs) exhibit cancer-like features, including promigratory and proinvasive activities that largely contribute to joint cartilage and bone destruction. In this study, we hypothesized that the NF of activated T cell 5 (NFAT5), a transcription factor involving tumor invasiveness, would control the migration and invasion of RA-FLSs. Analyses of transcriptomes demonstrated the significant involvement of NFAT5 in locomotion of RA-FLSs and that tissue factor (TF; also known as coagulation factor III) and CCL2 were the major downstream target genes of NFAT5 involving FLS migration and invasion. In cultured RA-FLSs, IL-1β and TGF-β increased TF and CCL2 expression by upregulating NFAT5 expression via p38 MAPK. Functional assays demonstrated that NFAT5- or TF-deficient RA-FLSs displayed decreased lamellipodia formation, cell migration, and invasion under IL-1β- or TGF-β-stimulated conditions. Conversely, factor VIIa, a specific activator of TF, increased migration of RA-FLSs, which was blocked by NFAT5 knockdown. Recombinant CCL2 partially restored the decrease in migration and invasion of NFAT5-deficient RA-FLSs stimulated with IL-1β. NFAT5-knockout mouse FLSs also showed decreased expressions of TF and CCL2 and reduced cell migration. Moreover, KRN2, a specific inhibitor of NFAT5, suppressed migration of FLSs stimulated with TGF-β. Conclusively, to our knowledge, this is the first study to provide evidence of a functional link between osmoprotective NFAT5 and TF in the migration and invasion of RA-FLSs and supports a role for NFAT5 blockade in the treatment of RA.

Follistatin-like protein 1 induction of matrix metalloproteinase 1, 3 and 13 gene expression in rheumatoid arthritis synoviocytes requires MAPK, JAK/STAT3 and NF-κB pathways.

Elevated levels of follistatin-like protein 1 (FSTL1) have been found both in mouse models for human rheumatoid arthritis (RA) and collagen-induced arthritis (CIA). In this study, we elucidated the potential mechanisms by which FSTL1 contributes to the pathogenesis of RA. Fibroblast-like synoviocytes (FLSs) were established from synovial tissues of RA patients and stimulated with human recombinant FSTL1. Protein and mRNA expression levels of select matrix metalloproteinases (i.e., MMP1, MMP3, MMP13) in FLS were measured by, respectively, real-time RT-qPCR and ELISA. Activation of MAPK and other pathways that affect MMPs were evaluated by Western blotting. We also compared concentrations of MMPs in plasma in RA patients versus healthy controls (HC). Expression levels of MMP1, MMP3, and MMP13 were clearly stimulated by FSTL1 in vitro. FSTL1 activated the inflammation-related NF-κB signaling pathway, as well as all three mitogen-activated protein kinase (MAPK) pathways and the JAK/STAT3 pathway. Moreover, select chemical inhibitors that target p38 (SB203580), Erk1/2 (SP600125), JNK (SCH772984), STAT3 (AG490), and NF-κB (BAY 11-7082) significantly attenuated MMP expression. Inhibition of Toll-like receptor 4 by compound TAK-242 significantly abolished those effects of FSTL1. Importantly, elevated plasma concentrations of MMP3 were found to correlate with plasma FSTL1 levels in RA patients. These findings suggest that FSTL1 accelerates RA progression by activating MAPK, JAK/STAT3, and NF-κB pathways to enhance secretion of different MMPs and this enhancement is via TLR4. Targeting FSTL1 may provide a promising pharmacological drug therapy to ameliorate RA symptoms and perhaps reverse disease progression.

Cyanidin-3-glucoside inhibits inflammatory activities in human fibroblast-like synoviocytes and in mice with collagen-induced arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint tissue inflammation. Cyanidin-3-glucoside (C3G) is a major component in the flavonoid family and has shown anti-inflammatory, anti-oxidant and anti-tumour activity. In this study, we investigated the effects of C3G on lipopolysaccharides (LPS)-induced inflammation on human rheumatoid fibroblast-like synoviocytes (FLS) and on collagen-induced arthritis (CIA) mice model. We treated FLS with C3G followed by LPS induction, the expressions of tumour necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β) and IL-6 and the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signalling pathway were analyzed. CIA was induced in mice and the arthritic mice were treated with C3G for 3weeks. The disease severity was compared between control and C3G treated mice. The serum levels of TNF-α, IL-1β and IL-6 were analyzed by ELISA. C3G inhibited LPS-induced TNF-α, IL-1β and IL-6 expression in FLS. Moreover, C3G inhibited LPS-induced p65 production and IκBa, p38, ERK and JNK phosphorylation. Administration of C3G significantly attenuated disease in mice with CIA and decreased the serum level of TNF-α, IL-1β and IL-6. C3G inhibited LPS-induced inflammation in human FLS by inhibiting activation of NF-κB and MAPK signalling pathway. C3G exhibited therapeutic effects in mice with CIA.

Anti-inflammatory Effect of Somatostatin Analogue Octreotide on Rheumatoid Arthritis Synoviocytes.

Somatostatin and its analogues are known to have modulatory effects on immune response and their anti-proliferative, anti-angiogenic, and analgesic properties make them attractive candidates for a therapeutic use in immune-mediated diseases, such as rheumatoid arthritis. Here, we demonstrate the ability of the somatostatin analogue octreotide to inhibit interleukin-15 and to increase interleukin-10 production by rheumatoid arthritis fibroblast-like synovial cells maintained in a chronic inflammatory state. We also prove that the inhibitory effect of octreotide on interleukin-15 and tumor necrosis factor-α production depended on the increase in interleukin-10, since neutralizing anti-interleukin-10 antibody was able to partially reverse this inhibition. In addition, our observations suggest an octreotide control on purinergic signaling, with an inhibitory effect on purinergic P2X and P2Y receptors activation. This would have great implications, considering the roles of P2 receptors in the onset of inflammation. Data here reported extend knowledge on the biological action of octreotide and underline its multiple effects on immune response, which could make octreotide an attractive and valid support for the therapy of diseases where several inflammatory mediators are involved, such as rheumatoid arthritis, and in which the simultaneous action on different aspects can be a successful strategy.

Madecassoside impedes invasion of rheumatoid fibroblast-like synoviocyte from adjuvant arthritis rats via inhibition of NF-κB-mediated matrix metalloproteinase-13 expression

Fibroblast-like synoviocytes (FLS) play a pivotal role in Rheumatoid arthritis (RA) pathogenesis through aggressive migration and invasion. Madecassoside (Madec), a triterpenoid saponin present in Centella asiatica herbs, has a potent anti-inflammatory effect. In the present study, Madec exerted an obvious therapeutic effect in reversing the histological lesions in adjuvant-induced arthritis (AIA) rats. To recognize the anti-rheumatoid potentials of Madec, we further investigated whether Madec interfered with FLS invasion and metalloproteinase (MMP) expression. In cultures of primary FLS isolated from the AIA rats, Madec (10 and 30 μmol·L−1) was proven to considerably inhibit migration and invasion of FLS induced by interleukin 1β (IL-1β), but exhibiting no obvious effect on cell proliferation. Madec repressed IL-1β-triggered FLS invasion by prohibiting the expression of MMP-13. Additionally, Madec suppressed MMP-13 transcription via inhibiting the MMP-13 promoter-binding activity of NF-κB. Our results further showed that Madec down-regulated the translocation and phosphorylation of NF-κB as demonstrated by Western blotting and immunofluorescence assays. In conclusion, our results suggest that Madec exerts anti-RA activity via inhibiting the NF-κB/MMP-13 pathway.

Effects of Jinwu Jiangu recipe on IL-17/STAT3 signals in rheumatoid arthritis synoviocytes

This paper aimed to investigate the effects of Jinwu Jiangu recipe total extract on the IL-17/STAT3 signals in rheumatoid arthritis synovial fibroblasts(RASF). The primary RASFs were cultured by tissue piece method in vitro， and divided into blank control group， Jinwu Jiangu recipe low dose group， Jinwu Jiangu recipe middle dose group， Jinwu Jiangu recipe high dose group， and tripterygium glycosides control group. They were then treated with corresponding serum free medium， different doses of Jinwu Jiangu recipe total extract(0.06， 0.6， 6.0 g·L⁻¹)， and tripterygium glycosides(0.03 g·L⁻¹) respectively for 24 hours. The gene expression levels of RORα， RORγt， and STAT3 mRNA were detected by polymerase chain reaction(PCR)， and the protein activity of IL-17R and pSTAT3 were measured by Western blot assay. The results showed that as compared with blank control group， the expression levels of RORα， RORγt， IL-17R and STAT3 mRNA in RASF were significantly declined(P<0.01). As compared with tripterygium glycosides control group， Jinwu Jiangu recipe total extract middle dose group and high dose group can down-regulate the expression levels of RORα， RORγt， IL-17R and STAT3 mRNA(P<0.05)， and the effect was more obvious in high dose group(P<0.01). As compared with blank control group， the protein expression levels of IL-17R and pSTAT3 in each treatment group were obviously decreased(P<0.01). As compared with tripterygium glycosides control group， Jinwu Jiangu recipe high dose group had more obvious effect in down-regulating the protein expression of pSTAT3(P<0.01). Therefore， Miao medicine Jinwu Jiangu recipe total extract can down-regulate the expressions of RORα， RORγt， and STAT3 mRNA， and inhibit the protein activity of IL-17R and pSTAT3 in RASF.

Oxymatrine prevents synovial inflammation and migration via blocking NF-κB activation in rheumatoid fibroblast-like synoviocytes

The fibroblast-like synoviocytes (FLSs) has the aggressive phenotype, which is very important for cartilage destruction in rheumatoid arthritis (RA). To the pathology of RA, the increased FLSs migration, activation and proliferation are essential factors. Oxymatrine is a traditional Chinese herb, which is the extraction from the root of Sophora flavescens and regarded as quinolizidine alkaloid compounds and has been shown to inhibit inflammation, proliferation and migration in vitro or vivo. However, whether oxymatrine effects in the treatment of RA FLSs is undefined. In our study, the inhibition of oxymatrine in RA FLSs inflammation, proliferation and migration in RA FLS are evaluated. We found that oxymatrine decreased the IL-6 and IL-8 expression and the proliferation, migration and invasion of RA FLSs. We also evaluated the molecular mechanisms and we found the effect of oxymatrine on NF-κB activation. The results showed that oxymatrine inhibited the activity of NF-κB. And the treatment activity of oxymatrine on collagen-induced arthritis (CIA) was further explored by us. Thus, we conclude that oxymatrine may protect joint destruction of RA by inhibiting synoviocyte activation, migration, invasion, and proliferation.

Mithramycin has inhibitory effects on gliostatin and matrix metalloproteinase expression induced by gliostatin in rheumatoid fibroblast-like synoviocytes

Objectives: Gliostatin (GLS) has angiogenic and arthritogenic activities and enzymatic activity as thymidine phosphorylase. Aberrant GLS production has been observed in the synovial membranes of patients with rheumatoid arthritis (RA). Matrix metalloproteinases (MMPs) are involved in joint destruction. Promoters of GLS and some MMP genes contain Sp1 binding sites. We examined the inhibitory effect of the Sp1 inhibitor mithramycin on GLS-induced GLS and MMP expression in cultured fibroblast-like synoviocytes (FLSs).Methods: Synovial tissue samples were obtained from patients with RA. FLSs pretreated with mithramycin were cultured with GLS. The mRNA expression levels of GLS and MMP-1, MMP-2, MMP-3, MMP-9, and MMP-13 were determined using reverse transcription polymerase chain reactions. Protein levels were measured using enzyme immunoassay and gelatin zymography.Results: GLS upregulated the expression of GLS itself and of MMP-1, MMP-3, MMP-9, and MMP-13, an effect significantly reduced by treatment with mithramycin. GLS and mithramycin had no effect on MMP-2 expression.Conclusions: Mithramycin downregulated the increased expression of GLS and MMP-1, MMP-3, MMP-9, and MMP-13 in FLSs treated with GLS. Because GLS plays a pathological role in RA, blocking GLS stimulation using an agent such as mithramycin may be a novel approach to antirheumatic therapy.

Interleukin-25 Produced by Synoviocytes Has Anti-inflammatory Effects by Acting As a Receptor Antagonist for Interleukin-17A Function.

The production and function of cytokines are highly regulated. One mechanism is the balance between pro- and anti-inflammatory cytokines. As interleukin (IL)-17A and IL-25 share the IL-17RA receptor chain, we hypothesize that IL-25 acts as an IL-17A receptor antagonist and limits its pro-inflammatory effects. The production and expression kinetics of IL-25 and its receptor chains IL-17RA and RB were analyzed in rheumatoid synoviocytes alone or in coculture with peripheral blood mononuclear cells (PBMCs). The effects of autocrine or exogenous IL-25 on synoviocytes were investigated in the presence or not of an anti-IL-25 antibody. To study the regulatory effects of IL-25, synoviocytes and/or PBMCs were exposed to IL-25 before being treated with IL-17A and tumor necrosis factor alpha (TNF-α) alone or combined. IL-25, IL-6, and bioactive IL-17A were quantified in rheumatoid arthritis (RA) patient plasma. Synoviocytes expressed and secreted IL-25, and expressed the two chains of its receptor IL-17RA and IL-17RB. IL-17RB expression was increased by TNF-α. IL-25 production occurred at a delayed time point (5 days) after stimulation with IL-17A and TNF-α. Synoviocytes pretreated with IL-25 were less responsive to IL-17A and TNF-α. PBMCs exposed to IL-25 showed a decreased production of pro-inflammatory mediators, including IL-17A with a 57% decrease; p = 0.002. IL-25 levels were elevated in the plasma of RA patients compared to healthy subjects (p = 0.03). However, these levels are not high enough to inhibit the function of circulating IL-17A. In conclusion, it was shown for the first time that synoviocytes produce IL-25, specifically at late time points and that IL-25 acts as a regulator of IL-17A-driven inflammation, as indicated by in vitro results and in vivo, in a long-term RA patient follow-up. These results may be important when considering IL-17A inhibition.

The autocrine role of proteoglycan-4 (PRG4) in modulating osteoarthritic synoviocyte proliferation and expression of matrix degrading enzymes

BackgroundLubricin/proteoglycan 4 (PRG4) is a mucinous glycoprotein secreted by synovial fibroblasts and superficial zone chondrocytes. Recently, we showed that recombinant human PRG4 (rhPRG4) is a putative ligand for CD44 receptor. rhPRG4-CD44 interaction inhibits cytokine-induced rheumatoid arthritis synoviocyte proliferation. The objective of this study is to decipher the autocrine function of PRG4 in regulating osteoarthritic synoviocyte proliferation and expression of catabolic and pro-inflammatory mediators under basal and interleukin-1 beta (IL-1β)-stimulated conditions.MethodsCytosolic and nuclear levels of nuclear factor kappa B (NFκB) p50 and p65 subunits in Prg4+/+ and Prg4-/- synoviocytes were studied using western blot. Nuclear translocation of p50 and p65 proteins in osteoarthritis (OA) fibroblast-like synoviocytes (FLS) in response to IL-1β stimulation in the absence or presence of rhPRG4 was studied using DNA binding assays. OA synoviocyte (5000 cells per well) proliferation following IL-1β (20 ng/ml) treatment in the absence or presence of rhPRG4 (50–200 μg/ml) over 48 hours was determined using a colorimetric assay. Gene expression of matrix metalloproteinases (MMPs), tissue inhibitor of metallproteinases-1 (TIMP-1), TIMP-2, IL-1β, IL-6, IL-8, TNF-α, cycloxygenae-2 (COX2) and PRG4 in unstimulated and IL-1β (1 ng/ml)-stimulated OA synoviocytes, in the presence or absence of rhPRG4 (100 and 200 μg/ml), was studied following incubation for 24 hours.ResultsPrg4-/- synoviocytes contained higher nuclear p50 and p65 levels compared to Prg4+/+ synoviocytes (p < 0.05). rhPRG4 (100 μg/ml) reduced p50 and p65 nuclear levels in Prg4+/+ and Prg4-/- synoviocytes (p < 0.001). Similarly, rhPRG4 (200 μg/ml) inhibited NFκB translocation and cell proliferation in OA synoviocytes in a CD44-dependent manner (p < 0.001) via inhibition of IκBα phosphorylation. IL-1β reduced PRG4 expression in OA synoviocytes and rhPRG4 (100 μg/ml) treatment reversed this effect (p < 0.001). rhPRG4 (200 μg/ml) reduced basal gene expression of MMP-1, MMP-3, MMP-13, IL-6, IL-8, and PRG4 in OA synoviocytes, while increasing TIMP-2 and cycloxygenase-2 (COX2) expression (p < 0.001). rhPRG4 (200 μg/ml) reduced IL-1β induction of MMP-1, MMP-3, MMP-9, MMP-13, IL-6, IL-8, and COX2 expression in a CD44-dependent manner (p < 0.001).ConclusionPRG4 plays an important anti-inflammatory role in regulating OA synoviocyte proliferation and reduces basal and IL-1β-stimulated expression of catabolic mediators. Exogenous rhPRG4 autoregulates native PRG4 expression in OA synoviocytes.

Platelet-rich plasma inhibits inflammatory factors and represses rheumatoid fibroblast-like synoviocytes in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic disease affecting daily life of numerous patients, and uncontrolled proliferation of synovial fibroblasts plays vital role during the pathology of RA. Platelet-rich plasma (PRP), widely used in tissue regeneration and pain management, is rarely studied in RA. This study aims to investigate the effect of PRP on synovial fibroblasts during RA. Rheumatoid fibroblast-like synoviocyte MH7A cells were stimulated by lipopolysaccharide (LPS) to simulate RA conditions and treated with PRP, after that the concentration of inflammatory factors interleukin (IL) 1β, tumor necrosis factor alpha (TNFα) and IL6 in the supernatant of culture medium was quantified by ELISA. MTT assay, flow cytometry and tube formation assay were performed to assess changes in cell viability, apoptosis and effect on angiogenesis in vitro, respectively. Besides, the expression levels of main factors in the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signal pathway were examined. Results showed that PRP markedly inhibited the production of IL1β, TNFα and IL6 (P<0.05) that was stimulated by LPS. LPS promoted MH7A cell viability, inhibited apoptosis and accelerated angiogenesis in vitro, while PRP could markedly relieve these effects (P<0.05). The mRNA and protein levels of AKT1, PI3K (p58) and nuclear factor κ beta were elevated by LPS and then suppressed by PRP (P<0.01). This study uncovered the potential of PRP in inhibiting inflammation, repressing synovial fibroblasts and regulating the PI3K/AKT signaling, providing basic proof for future application of PRP in managing RA. Further investigation is necessary to reveal detailed mechanism of PRP.

IL-34 Upregulated Th17 Production through Increased IL-6 Expression by Rheumatoid Fibroblast-Like Synoviocytes.

Rheumatoid arthritis (RA) is a chronic autoimmune disease which is characterized by synovial inflammation and cartilage damage for which causes articular dysfunction. Activation of fibroblast-like synoviocytes (FLS) is a critical step that promotes disease progression. In this study, we aimed to explore the effect of interleukin-34 (IL-34) on RA FLS as a proinflammatory factor and IL-34-stimulated FLS on the production of Th17. We found that serum IL-34 levels were increased compared to those of the healthy controls and had positive correlations with C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), and anticyclic citrullinated peptide (CCP) antibody accordingly. CSF-1R was also highly expressed on RA FLS. The interaction of IL-34 and CSF-1R promoted a dramatic production of IL-6 by FLS through JNK/P38/NF-κB signaling pathway. Further, the IL-34-stimulated IL-6 secretion by RA FLS was found to upregulate the number of Th17. The treatment of IL-6R antagonist could attenuate the production of Th17 mediated by IL-34-stimulated RA FLS. Our results suggest that the increased IL-34 levels were closely related to the disease activity of RA. Additionally, the overexpression of IL-6 in the IL-34-stimulated FLS promoted the generation of Th17. Therefore, IL-34 was supposed to be involved in the pathogenesis of RA. The inhibition of IL-34 might provide a novel target for therapies of RA.

Brahma-related gene 1 induces apoptosis in a p53-dependent manner in human rheumatoid fibroblast-like synoviocyte MH7A.

Blocked apoptosis and aggressive inflammatory responses occur in fibroblast-like synoviocyte (FLS) of rheumatoid arthritis (RA) patients. Although Brahma-related gene 1 (BRG1) is considered as a tumor suppressor, few research covers its role in RA. This study aims to reveal effects and potential mechanisms of BRG1 in human FLS cell line MH7A.BRG1 expression in MH7A cells was altered by transfection of overexpression vectors or short hairpin RNAs (shRNAs). Cell viability and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry after transfection. Factors involved in inflammation and apoptosis were quantified by qPCR and Western blot. The interaction between BRG1 and p53 was assessed by immunoprecipitation (IP).Results showed that BRG1 overexpression significantly suppressed MH7A cell viability and induced apoptosis (P < 0.01), and its knockdown had opposite effects. BRG1 reduced mRNA levels of matrix metallopeptidase 3, TIMP metallopeptidase inhibitor 2, cyclooxygenase 2, and interleukin 6, implying its suppressive effects on inflammation. BRG1 interacted with and promoted p53 (P < 0.05). B-cell chronic lymphocytic leukemia/lymphoma 2 was suppressed (P < 0.05), while cytochrome c, caspase 3 (CASP3) and CASP9 were activated (P < 0.01) by BRG1. However, the regulation on these factors was abrogated by p53 knockdown (P < 0.01).These findings suggest that BRG1 may induce apoptosis and suppress inflammation in MH7A cells. Potential functional mechanisms involve the regulation of apoptotic factors by BRG1, which may depend on the recruitment and promotion of p53. This study provides the essential proof for applying BRG1 to the molecular therapy of RA.