miR‐124a inhibits the proliferation and inflammation in rheumatoid arthritis fibroblast‐like synoviocytes via targeting PIK3/NF‐κB pathway

: Abnormal hyperplasia of fibroblast-like synoviocytes (FLS) leads to the progression of rheumatoid arthritis (RA). This study aimed to investigate the role of miR-124a in the pathogenesis of RA. The viability and cell cycle of FLS in rheumatoid arthritis (RAFLS) were evaluated by Cell Counting Kit 8 and flow cytometry assay. The expression of PIK3CA, Akt, and NF-κB in RAFLS was examined by real-time PCR and Western blot analysis. The production of tumour necrosis factor (TNF)-α and interleukin (IL)-6 was detected by ELISA. The joint swelling and inflammation in collagen-induced arthritis (CIA) mice were examined by histological and immunohistochemical analysis. We found that miR-124a suppressed the viability and proliferation of RAFLS and increased the percentage of cells in the G1 phase. miR-124a suppressed PIK3CA 3'UTR luciferase reporter activity and decreased the expression of PIK3CA at mRNA and protein levels. Furthermore, miR-124a inhibited the expression of the key components of the PIK3/Akt/NF-κB signal pathway and inhibited the expression of pro-inflammatory factors TNF-α and IL-6. Local overexpression of miR-124a in the joints of CIA mice inhibited inflammation and promoted apoptosis in FLS by decreasing PIK3CA expression. In conclusion, miR-124a inhibits the proliferation and inflammation in RAFLS via targeting PIK3/NF-κB pathway. miR-124a is a promising therapeutic target for RA.