MicroRNA-27a alleviates IL-1β-induced inflammatory response and articular cartilage degradation via TLR4/NF-κB signaling pathway in articular chondrocytes

Osteoarthritis (OA) is a common disease of the articular cartilage, and inflammatory response and articular cartilage degradation have been implicated in the pathogenesis of OA. In recent years, microRNAs (miRNAs) have been potentially involved in the pathogenesis of OA. However, little is known about the role of miRNAs in the inflammatory response and articular cartilage degradation in OA and the underlying molecular mechanism. In the present study, we analyze miRNA profiles in the articular tissues from OA patients using microarray. miR-27a has attracted considerable interest for its suppressive effects on inflammation. Subsequently, the expression levels of miR-27a were validated in the articular tissues of OA patients and IL-1β-stimulated chondrocytes. Using this IL-1β-induced chondrocyte injury model, we found that upregulation of miR-27a suppressed articular cartilage degradation, the reactive oxygen species (ROS) production and inflammatory response as reflected by reductions in pro-inflammatory cytokines, including interleukin (IL)-6 and IL-8 and tumor necrosis factor (TNF)-α. Moreover, toll-like receptor 4 (TLR4), one upstream molecule of NF-κB signaling pathway, was identified as a direct target of miR-27a in chondrocytes. Furthermore, it was demonstrated that overexpression of TLR4 by pcDNA-TLR4 markedly abrogated the inhibitory effects of miR-27a on the inflammatory response and the degeneration of articular cartilage induced by IL-1β. Our findings suggest that miR-27a may be considered as a potential therapeutic target in the treatment of OA.