Acid Sphingomyelinase and Acid ß-Glucosidase 1 Exert Opposite Effects on Interleukin-1ß-Induced Interleukin 6 Production in Rheumatoid Arthritis Fibroblast-Like Synoviocytes.

Acid sphingomyelinase (ASM) and acid ß-glucosidase 1 (GBA1) catalyze ceramide formation through different routes, and both are involved in rheumatoid arthritis (RA) pathogenesis as well as IL-6 production. However, whether ASM and GBA1 regulate IL-6 production in RA remains unknown. Serum ASM, GBA1, and ceramide levels were measured in RA patients and healthy controls by enzyme-linked immunosorbent assay, and their correlations with clinical indicators of patients were evaluated. Pharmacologic inhibitors or small hairpin RNAs of ASM and GBA1 were employed to explore the roles of ASM and GBA1 in IL-6 production, cell behavior, and MAPK signaling in fibroblast-like synoviocytes from RA patients (RAFLS). ASM, GBA1, and ceramide serum levels were significantly elevated in patients with RA. GBA1 and ceramide serum levels were negatively and positively correlated with IL-6 serum level in RA patients, respectively. ASM inhibitor or knockdown of ASM abolished IL-1ß-induced IL-6 expression and secretion. Functionally, ASM inhibitor suppressed IL-1ß-induced cell proliferation, migration, and invasion in RAFLS. Mechanistically, ASM inhibitor or knockdown of ASM effectively countered IL-1ß-induced activation of p38 MAPK signaling. The pharmacologic inhibitor or knockdown of GBA1 exhibited the opposite effects. Importantly, p38 inhibitor blocked IL-1ß-induced IL-6 production in RAFLS. ASM plays a pathogenic role in RA, whereas GBA1 plays a protective role in RA possibly by regulating IL-6 production in RAFLS at least partially via p38 signaling, serving as potential therapeutic targets in RA treatment.

miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP.

BACKGROUND: miR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood. METHODS: Quantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs. RESULTS: miR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition but promoted apoptosis in RA FLSs, while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs. CONCLUSION: miR-431-5p regulates cell proliferation, apoptosis, and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

Pentraxin 3 inhibits fibroblast growth factor 2 induced osteoclastogenesis in rheumatoid arthritis.

BACKGROUND: Synovial fibroblasts (SFs) act as key effector cells mediating synovial inflammation and joint destruction in rheumatoid arthritis (RA). Fibroblast growth factor 2 (FGF2) and its receptors (FGFRs) play important roles in RASF-mediated osteoclastogenesis. Pentraxin 3 (PTX3) is a soluble pattern recognition receptor with nonredundant roles in inflammation and innate immunity. PTX3 is produced by various cell types, including SFs and is highly expressed in RA. However, the role of PTX3 in FGF2-induced osteoclastogenesis in RA and the underlying mechanism have been poorly elucidated. METHODS: We first determined the expression of FGF2 and RANKL in synovial tissue and synovial fluid of RA patients. We then examined the effect of PTX3 on RASF osteoclastogenesis induced by endogenous and exogenous FGF2 in isolated RASF cells treated with FGF2 and/or recombinant PTX3 (rPTX3). Thirdly, we analyzed the effect of PTX3 on FGF2 binding to FGFR-1 and HSPG receptors on RASFs. Lastly, we evaluated joint morphology after injection of rPTX3 into collagen-induced arthritis (CIA) mice. RESULTS: FGF2 was confirmed to be highly expressed in both synovial tissue and synovial fluid of RA patients. FGF2 promoted cell proliferation and increased the expressions of RANKL and ICAM-1 and RANKL/OPG to induce osteoclastogenesis in RASF, while anti-FGF2 neutralized this effect. PTX3 significantly inhibited FGF2-induced RASF cell growth and osteoclastogenesis by preventing the interaction of 125I-FGF2 and FGFRs on the same cells. In addition, administration of rPTX3 significantly ameliorated cartilage and bone destruction in mice with CIA. CONCLUSIONS: PTX3 exhibited an inhibitory effect on the autocrine and paracrine stimulation of FGF2 on SFs, and ameliorated bone destruction in CIA mice. PTX3 may be implicated in bone destruction in RA, which may provide theoretical evidence and potential therapeutic targets for RA treatment.

LncRNA NEAT1 Targets Fibroblast-Like Synoviocytes in Rheumatoid Arthritis via the miR-410-3p/YY1 Axis.

LncRNA NEAT1 functions as an oncogene in multiple human cancers. However, its expression and role in fibroblast-like synoviocytes (FLSs) from patients with rheumatoid arthritis (RA) remain unclear. Thus, we investigated the expression of NEAT1 in synovial tissues and FLSs in RA, to determine its role in the development of RA. Quantitative real-time polymerase chain reaction was used to measure the expression of NEAT1. FLS proliferation was evaluated using cell proliferation assays. Flow cytometry was used to analyze cell cycle progression and apoptosis in FLSs. Binding between NEAT1 and miR-410-3p was demonstrated by dual-luciferase assays. We found that NEAT1 was upregulated in synovial tissues and FLSs in RA. Upregulation of NEAT1 promoted cell proliferation, induced S-to G2/M phase transition, and suppressed apoptosis in RA FLSs. NEAT1 directly bound to and negatively modulated miR-410-3p expression, while positively regulating YinYang 1(YY1; a miR-410-3p target). Inhibiting miR-410-3p and upregulating YY1 partially restored the inhibitory role in cell viability induced by the depletion of NEAT1 in RA FLSs. Besides pro-proliferative and anti-apoptotic roles, upregulation of NEAT1 promoted migration, invasion, and inflammatory cytokines secretion in RA FLSs. Taken together, our results suggest that the NEAT1 may serve as a novel diagnostic and therapeutic target for patients with RA.

miR-483-3p promotes cell proliferation and suppresses apoptosis in rheumatoid arthritis fibroblast-like synoviocytes by targeting IGF-1.

Accumulating evidence suggests that miR-483-3p is implicated in maintaining biological properties in human cancers. However, its biological roles in rheumatoid arthritis (RA) remain unknown. miR-483-3p levels in synovial tissue samples and fibroblast-like synoviocytes (FLSs) were determined using quantitative real-time PCR. The CCK-8 assay and EdU staining were performed to assess cell proliferation in RA FLSs after transfection with miR-483-3p mimics or inhibitor. Flow cytometry with Annexin V-FITC staining or PI staining was performed to assess apoptosis or cell cycle progression in RA FLSs, respectively. miR-483-3p was upregulated in RA, which markedly promoted cell proliferation, induced the G0/G1-to-S phase transition, and suppressed apoptosis in RA FLSs, whereas miR-483-3p silencing yielded opposite results. Moreover, insulin growth factor 1 (IGF-1) was detected as a direct miR-483-3p target. IGF-1 silencing partially restored cell proliferation, the G0/G1-to-S phase transition, and apoptosis suppression in RA FLSs via miR-483-3p inhibition. Our results showed that miR-483-3p promotes RA FLSs proliferation by targeting IGF-1, suggesting a potential strategy for diagnostic and treatment strategy for RA.

Obesity promotes the global hypomethylation of CD4+ T cells in patients with systemic lupus erythematosus via downregulating DNMT1.

BACKGROUND: The global hypomethylation of CD4+ T cells in Systemic Lupus Erythematosus (SLE) patients has been previously reported. However, potential influencing factors are unclear. This study aims to uncover the potential influence of obese on hypomethylated CD4+ T cells in SLE patients. METHODS: Obese SLE patients with body mass index (BMI) > 30 (n=15) and normal weight SLE patients with 18 < BMI < 25 (n=20) were included. SLEADI, nRNP and dsDNA levels in them were detected. Methylation rate of CD4+ T cells isolated from SLE patients was assessed, as well as its correlation to BMI and systemic lupus erythematosus disease activity index (SLEADI) in SLE patients. Subsequently, relative level and catalytic activity of DNA (cytosine-5)-methyltransferase 1 (DNMT1) were examined. New Zealand Black/White (NZB/W) mice were fed high-fat diet for generating obesity model or normal diet, followed by detection of anti-nuclear-ribonuclear-protein (nRNP) immumoglobulin G (IgG), anti-double-stranded (ds) DNA IgG, methylation rate of CD4+ T cells and DNMT1 level. RESULTS: SLEADI, nRNP and dsDNA levels were higher in obese SLE patients than normal weight cases. SLEADI was positively correlated to BMI in included SLE patients. Compared with normal weight SLE patients, methylation rate of CD4+ T cells was lower in obese patients. DNMT1 was downregulated in obese SLE patients, and its level was negatively correlated to BMI in SLE patients. Consistently, methylation rate of CD4+ T cells and DNMT1 level remained lower in obese SLE mice than those normally fed mice with SLE. CONCLUSIONS: Hypomethylated CD4+ T cells extensively occur in SLE patients, which are much more pronounced in obese cases. DNMT1 level is found to be negatively correlated to the methylation rate of CD4+ T cells in SLE patients.

Meta-analysis of IL-17 inhibitors in two populations of rheumatoid arthritis patients: biologic-naïve or tumor necrosis factor inhibitor inadequate responders.

OBJECTIVES: To evaluate the efficacy and safety of interleukin 17 (IL-17) inhibitors in two rheumatoid arthritis (RA) populations: biologic-naïve or tumor necrosis factor inhibitor inadequate responders (TNF-IR). METHOD: A systematic search was performed in major electronic databases to identify relevant randomized controlled trials (RCTs) reporting the American College of Rheumatology 20% (ACR20), ACR50, ACR70 responses and adverse events (AEs) of IL-17 inhibitors versus placebo in patients with RA. We divided these patients into two subgroups: biologic-naïve or TNF-IR. The meta-analysis was performed using Review Manager 5.3 software. Results were expressed as risk ratio (RR) with pertinent 95% confidence interval (95% CI). RESULTS: Ten studies with a total of 2499 patients were included. For biologic-naïve patients, ACR50 and ACR70 responses were significantly better with IL-17 inhibitors than placebo (RR = 1.71, 95% CI 1.23-2.38, P = 0.001 and RR = 2.63, 95% CI 1.10-6.25, P = 0.03, respectively), but ACR20 responses for IL-17 inhibitors were not statistically superior to placebo (RR = 1.34, 95% CI 0.94-1.91, P = 0.11). For TNF-IR, IL-17 inhibitors were effective in achieving ACR20 (RR = 1.67, 95% CI 1.40-2.00, P < 0.00001), ACR50 (RR = 1.94, 95% CI 1.43-2.63, P < 0.0001), and ACR70 (RR = 2.11, 95% CI 1.26-3.55, P = 0.005) compared to placebo. In the safety analysis, IL-17 inhibitors did not show increased risk of any AEs by comparing to placebo in both biologic-naïve patients and TNF-IR. CONCLUSION: IL-17 inhibitors were effective in the treatment of RA without increased risk of AEs, whether for biologic-naïve patients or TNF-IR. Key Points • In this meta-analysis comparing IL-17 inhibitors with placebo in 2499 rheumatoid arthritis patients, IL-17 inhibitors improved ACR50 and ACR70, but not ACR20, responses in biologic-naïve patients. • IL-17 inhibitors improved ACR20, ACR50, and ACR70 responses in tumor necrosis factor inhibitor inadequate responders.

Efficacy of anti-tumor necrosis factor therapy for extra-articular manifestations in patients with ankylosing spondylitis: a meta-analysis.

BACKGROUND: We performed a meta-analysis to evaluate the effect of anti-tumor necrosis factor (TNF) therapy on the frequency of extra-articular manifestations (EAMs) in patients with ankylosing spondylitis (AS). METHODS: We searched with the terms 'ankylosing spondylitis', 'infliximab', 'etanercept', 'adalimumab', 'golimumab', 'certolizumab', 'TNF inhibitor/blocker/antagonists' or 'anti-TNF' on MEDLINE, EMBASE and Cochrane Library for randomized controlled trials (RCTs) of ≥ 12 weeks with parallel or crossover design of TNF inhibitor versus placebo to treat uveitis, inflammatory bowel disease (IBD) and/or psoriasis of AS, published before February 2014. RESULTS: We found 8 RCTs that fit our criteria. Anti-TNF therapy was associated with less uveitis than placebo in patients with AS (OR: 0.35, 95% CI: 0.15-0.81, P = 0.01). Subgroup analysis showed receptor fusion proteins were more efficacious for uveitis than placebo (OR: 0.30, 95% CI: 0.09-0.94, P = 0.04), but monoclonal antibodies were not (OR: 0.43, 95% CI: 0.12-1.49, P = 0.18). Anti-TNF therapy and placebo group did not significantly differ in treating IBD in AS patients (OR: 0.75, 95% CI: 0.25-2.29, P = 0.61). In subgroup analysis, neither monoclonal antibodies (OR: 0.45, 95% CI: 0.10-1.92, P = 0.28) nor receptor fusion proteins (OR: 1.52, 95% CI: 0.25-9.25, P = 0.65) significantly differed from placebo in treating IBD. We found no suitable reports on psoriasis. CONCLUSIONS: Anti-TNF therapy was preventive for flares or new onset of uveitis in AS patients, and might be an alternative for these patients. However, monoclonal anti-TNF antibodies and TNF receptor fusion proteins were not efficacious for IBD in AS patients.

Increased interleukin-23 is associated with increased disease activity in patients with rheumatoid arthritis.

BACKGROUND: Interleukin-23 (IL-23) is a pro-inflammatory cytokine that is thought to be central to the development of autoimmune diseases. This study was conducted to determine whether or not the serum concentration of IL-23 is elevated in patients with rheumatoid arthritis (RA), and to determine the relationship between the IL-23 level and disease activity in RA patients. METHODS: Serum samples were obtained from 59 patients with RA and 30 healthy controls. The clinical parameters of disease activity were determined, including the 28-joint disease activity score (DAS28), C-reactive protein (CRP), rheumatoid factor (RF) levels, and the degree of bony erosions based on X-rays. The levels of IL-23 and IL-17 were determined by enzyme-linked immunosorbent assay (ELISA). The correlations between the serum levels of IL-23 and disease activity parameters of patients with RA were determined. RESULTS: The serum IL-23 level was significantly elevated in patients with RA compared to healthy controls. The serum IL-23 levels in the RA patients correlated with IL-17 and CRP levels, and the DAS28. The levels of IL-23 based on X-ray classification phase I, II, III, and IV were gradually elevated in RA patients. CONCLUSIONS: The levels of serum IL-23 in RA patients were higher than in healthy controls. Thus, elevated serum IL-23 levels may be useful markers to detect active RA. In addition, IL-23 is involved in disease progression and bony erosions in patients with RA.

Effect of tumor necrosis factor inhibitors on rheumatoid arthritis-induced peripheral neuropathy: A cohort study.

In this historical cohort study, 236 patients with primary rheumatoid arthritis were treated with the tumor necrosis factor inhibitors, etanercept or infliximab (n = 80), or by conventional methods (n = 156). Results revealed that 11 patients developed varying types of peripheral neuropathy at 1-2 years post-treatment (mean 16 months). The incidence of peripheral neuropathy in the tumor necrosis factor inhibitors treatment group was 8.8% (7/80), which was significantly higher than the conventional treatment group (2.6%; 4/156). The relative risk of developing peripheral neuropathy in the tumor necrosis factor inhibitors treatment group was 3.41 (95% confidence interval: 1.03-11.31). Comparison of the tumor necrosis factor inhibitors revealed that etanercept and infliximab had no significant difference in terms of inducing peripheral neuropathy. Experimental findings indicate that tumor necrosis factor inhibitors may increase the risk of peripheral neuropathy.