Protective effect of cartilage oligomeric matrix protein (COMP) on osteoarthritis-like chondrocytes based on the nuclear factor kappa B (NF-κB) pathway

To explore the potential regulatory mechanism of the nuclear factor kappa B (NF-κB) pathway and cartilage oligomeric matrix protein (COMP) in the pathogenesis of osteoarthritis (OA), and to provide possible targets for the treatment and prevention of OA. Mouse bone marrow mesenchymal stem cells (BMSCs) were isolated and cultured in vitro. The third-generation cells were taken to identify the expression of surface markers CD90, CD29, CD34, and CD11b by flow cytometry. The BMSCs with higher purity were selected. Dexamethasone was used to induce cartilage differentiation, and the surface characteristics of osteoblasts were detected by alkaline phosphatase staining and alizarin red staining. Interleukin-1β (IL-1β) was used to induce chondrocytes to establish an in vitro OA-like cell model. The activation of the NF-κB pathway was detected by enzyme-linked immunosorbent assay (ELISA). The NF-κB pathway was activated by RNAi interference, and mRNA levels of inflammatory factors interleukin-6 (IL-6),cyclooxygenase 2 (COX-2), matrix metalloproteinases-3(MMP-3) and MMP-9 regulated by NF-κB pathway were detected by real-timepolymerase chain reaction (RT-PCR).The effect of activation of the NF-κB pathway on the expression of the COMP gene was detected by RT-PCR and chromatin immunoprecipitation (ChIP) analysis. RT-PCR and ELISA were used to detect the effect of exogenously added COMP on the apoptosis pathway mediated by the NF-κB pathway and the expression of inflammatory factors. Isolated and purified mouse BMSCs can undergo chondrogenic differentiation. During the induction of IL-1β, the contents of IL-6 and COX-2 in chondrocytes were significantly increased, and the activity of chondrocytes was significantly decreased. The mRNA levels of IL-6 and COX-2 and MMP-3 and MMP-9 in OA-like chondrocytes were significantly increased, and this effect was partially suppressed following NF-κB pathway inhibition. Transient activation of the NF-κB pathway down-regulates the expression of the COMP gene mRNA levels. Exogenous COMP has a protective effect on OA-like chondrocytes, and its mechanism may be to reduce inflammation and apoptosis by regulating downstream signaling events of NF-κB activation. These findings extend our current understanding of the pathological mechanism of OA and provide an important target for its treatment and prevention.