The development of osteoarthritis (OA) is characterized by synovial inflammation and the upregulation of vascular cell adhesion molecule type 1 (VCAM-1) in human osteoarthritis synovial fibroblasts (OASFs). This increase in VCAM-1 expression promotes monocyte adhesion to OASFs. The adipokine resistin is known to promote the release of inflammatory cytokines during OA progression. In this study, we identified significantly higher levels of resistin and CD68 (a monocyte surface marker) expression in human OA tissue compared with in healthy control tissue. We also found that resistin enhances VCAM-1 expression in human OASFs and facilitates the adhesion of monocytes to OASFs. These effects were attenuated by inhibitors of PKCα, p38, and JNK; their respective siRNAs; and by a microRNA-381 (miR-381) mimic. In our anterior cruciate ligament transection (ACLT) rat model of OA, the inhibition of resistin activity prevented ACLT-induced damage to the OA rat cartilage and pathological changes in resistin and monocyte expression. We also found that resistin affects VCAM-1 expression and monocyte adhesion in human OASFs by inhibiting miR-381 synthesis via the PKCα, p38, and JNK signaling pathways. Our clarification of the crucial role played by resistin in the pathogenesis of OA may lead to more effective therapy that reduces OA inflammation.
Keywords: VCAM-1; miR-381; monocytes; osteoarthritis; resistin.