Interferon regulatory factor 5 (IRF5) regulates the expression of matrix metalloproteinase-3 (MMP-3) in human chondrocytes

Matrix metalloproteinase-3 (MMP-3) plays a pivotal role in the destruction of articular cartilage in osteoarthritis (OA). The regulation of gene expression of MMP-3 is complicated. Interferon regulatory factor 5 (IRF5) is a member of the interferon regulatory factor family of transcription factors. Little information regarding the biological function of IRF5 on chondrocytes and the pathogenesis of OA has been reported. In the current study, for the first time, we report that IRF5 is expressed in human primary chondrocytes and human chondrosarcoma cell line SW1353 cells. In addition, IRF5 is upregulated in response to TNF-alpha treatment in a dose dependent manner. Interestingly, IRF5 is significantly higher in chondrocytes from OA patients compared to those from normal subjects. Notably, IRF5 mediates TNF-alpha- induced expression of MMP-3 in chondrocytes. Overexpression of IRF5 promotes the expression of MMP-3, however, knockdown of IRF5 reduces the expression of MMP-3. Mechanistically, IRF5 is able to enhance the transcription of MMP-3 by binding to its promoter. Also, we found that NF-kappa B was involved in the effects of IRF-5 on MMP-3 expression. These findings suggest that IRF5 might be a novel pharmacological target for the treatment of OA and RA.