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Objective: Rheumatoid arthritis (RA) is the most frequently occurring inflammatory arthritis. The present study was performed to characterize the role of microRNA-101-3p (miR-101-3p) and prostaglandin-endoperoxide synthase 2 (PTGS2) in inflammation and biological activities of fibroblast-like synoviocytes (FLSs) in RA. Methods: Initially, miR-101-3p and PTGS2 expression in RA tissues of RA patients and RA rats was detected by qRT-PCR and Western blot analysis. Rat model of type II collagen-induced arthritis (CIA) was adopted to simulate RA, followed by injection of miR-101-3p mimics or siRNA against PTGS2. Next, the apoptosis in synovial tissue and the levels of tumor necrosis factor (TNF)-α, IL-1β and IL-6 were identified. Subsequently, FLSs in RA (RA-FLSs) were isolated, after which in vitro experiments were conducted to analyze cell proliferation, apoptosis, migration and invasion upon treatment of up-regulated miR-101-3p and silenced PTGS2. Furthermore, the relationship of miR-101-3p and PTGS2 was determined by bioinformatics prediction and luciferase activity assay. Results: We identified poorly expressed miR-101-3p and highly expressed PTGS2 in synovial tissues of RA patients and RA rats, which showed reduced synoviocyte apoptosis and enhanced inflammation. In response to miR-101-3p mimics and si-PTGS2, the RA-FLSs were observed with attenuated cell proliferation, migration and invasion, corresponding to promoted apoptosis. Down-regulation of PTGS2 could rescue the effect of inhibited miR-101-3p in synovial injury and phenotypic changes of FLS in RA rats. Notably, miR-101-3p was found to negatively regulate PTGS2. Conclusion: Taken together, miR-101-3p reduces the joint swelling and arthritis index in RA rats by down-regulating PTGS2, as evidenced by inhibited FLS proliferation and inflammation.

The present study aimed to investigate the anti-arthritic effect of physcion 8-O-β-glucopyranoside (POGD) and its possible mechanisms. The anti-proliferative effects of POGD on MH7A cells were detected using a CCK-8 assay, and the release of pro-inflammatory cytokines, interleukin (IL)-1β, IL-6, IL-8, IL-12 and IL-17A, were determined by ELISA. A type II collagen-induced arthritis (CIA) rat model was established to evaluate the anti-arthritic effect of POGD in vivo. The paw volumes, arthritis indices and serum levels of tumor necrosis factor (TNF)-α, IL-1β, IL-6, IL-8, IL-17A were determined by ELISA. The mRNA expression levels of matrix metalloproteinase (MMP)-2, MMP-3, MMP-9, vascular endothelial growth factor and cyclooxygenase-2 were determined by reverse transcription-quantitative polymerase chain reaction analysis, and the expression levels of transforming growth factor (TGF)-β1, small mothers against decapentaplegic (Smad)4, Smad7, c-Jun N-terminal kinase (JNK), phosphorylated (p-)JNK, p-P38, P38, p-extracellular signal-regulated kinase (ERK)1/2, ERK1/2, nuclear factor (NF)-κB p65 in the nucleus (N), cytosolic NF-κB p65 (C), and inhibitor of NF-κB (IκB) were determined by western blot analysis. The results indicated that POGD significantly inhibited MH7A cell growth. POGD markedly inhibited paw swelling and the arthritis indices of the CIA rats, and POGD may also inhibit the release of pro-inflammatory cytokines. Furthermore, POGD downregulated the expression levels of TGF-β1, Smad4, NF-κB p65 (N), p38, p-p38, p-ERK1/2, JNK, p-JNK, TGF-β1, Smad4, p-JNK, JNK, p-P38, P38, p-ERK1/2, ERK1/2 and NF-κB p65 (N), and upregulated the Smad7, NF-κB p65 (C) and IκB in TNF-α induced MH7A cells. In conclusion, the results suggested that POGD is a promising potential anti-inflammatory drug, and that POGD may decrease the expression of pro-inflammatory cytokines and mediators via inhibiting the TGF-β/NF-κB/mitogen-activated protein kinase pathways.

Aim The increased level of interleukin‐6 (IL‐6) plays a significant role in the pathogenesis of rheumatoid arthritis (RA). Specific blockade of IL‐6 or its receptor has been used successfully in treating RA. MicroRNAs can regulate gene expression and act as regulators of target genes. Manipulation of specific microRNAs provides a novel therapeutic strategy for treating/preventing diseases. This study explored the role of miR‐98‐5p in the regulation of IL‐6 expression in rheumatoid fibroblast‐like synoviocytes (RA‐FLSs). Methods Real‐time PCR was used to detect miR‐98‐5p expression in RA‐FLSs and normal human fibroblast‐like synovial cells (HFLSs). Site‐directed gene mutagenesis and reporter gene assay were performed to identify the interaction between miR‐98‐5p and IL‐6. Manipulation of miR‐98‐5p expression in RA‐FLS used transfection with miR‐98‐5p mimic or inhibitor. Stimulation of FLSs with IL‐1β induced IL‐6 production. Enzyme‐linked immunosorbent assay was used to detect the level of IL‐6 secreted into the RA‐FLS culture supernatant. Results Compared with HFLSs, the expression of miR‐98‐5p in RA‐FLSs was significantly downregulated, and was negatively correlated with DAS28 scores and rheumatoid factor. In patients with anti‐keratin antibody‐positive RA, the expression level of miR‐98‐5p was lower. miR‐98‐5p negatively regulated the expression of IL‐6 in RA‐FLSs. After IL‐1β stimulation, the expression of miR‐98‐5p decreased and the level of IL‐6 protein was upregulated during IL‐6 secretion. Conclusion These data suggest that manipulation of miR‐98‐5p, which negatively modulates IL‐6 expression, may be a potential clinical approach in RA.

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