Andrographolide suppresses osteoarthritis progression by regulating circ_Rapgef1/miR-383-3p/NLRP3 signaling axis

Andrographolide (AD) has been reported to play a potential anti-arthritic role by facilitating the proliferation and inhibiting the apoptosis of chondrocytes. However, the molecular mechanism underlying the protective role of AD in osteoarthritis (OA) remains to be elucidated. OA mice model was established via anterior cruciate ligament transection (ACLT) operation. OA cell model was established through treating mice primary chondrocytes with LPS (1 μg/mL, 24 h). Enzyme-linked immunosorbent assay (ELISA) was performed to measure the concentrations of inflammatory cytokines in the supernatant. Cell proliferation was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and 5-Ethynyl-2′-deoxyuridine (EdU) assay. Cell apoptosis was evaluated by flow cytometry. The intermolecular interaction was verified by dual-luciferase reporter assay. AD administration reduced the infiltration of inflammatory cells in the synovial tissues of ankle joint and suppressed the inflammatory response in OA mice model in vivo. Lipopolysaccharide (LPS) stimulation suppressed the proliferation and induced the apoptosis and inflammation of chondrocytes, and AD treatment protected chondrocytes from LPS-induced dysfunction. Circular RNA (circRNA) Rap guanine nucleotide exchange factor 1 (circ_Rapgef1) overexpression attenuated AD-mediated protective effects in OA cell model. Circ_Rapgef1/microRNA-383-3p (miR-383-3p)/Nod-like receptor pyrin domain 3 (NLRP3) axis was identified in this study for the first time. Circ_Rapgef1 overexpression-mediated effects were partly reversed by the overexpression of miR-383-3p in chondrocytes. NLRP3 silencing partly overturned miR-383-3p knockdown-mediated effects in chondrocytes. Circ_Rapgef1 overexpression up-regulated the expression of NLRP3 partly by targeting miR-383-3p in chondrocytes. Circ_Rapgef1 suppressed AD-mediated protective effects in OA partly by regulating miR-383-3p/NLRP3 signaling.