MiR-27a alleviates osteoarthritis in rabbits via inhibiting inflammation

To investigate the regulatory effect of micro ribonucleic acid-27a (miR-27a) on the nuclear factor-kappa B (NF-κB) pathway and to explore its effect on rabbits with osteoarthritis (OA).

Anterior cruciate ligament (ACL) cross-section method was adopted to establish OA rabbit models. Cartilage specimens were collected to detect expression levels of miR-27a in OA cartilage and normal cartilage tissues. Meanwhile, chondrocytes were isolated and cultured, and transfected with miR-27a mimics and miR-27a inhibitor. Blank control group was set up. Next, the changes in chondrocyte proliferation were detected using 5-ethynyl-2'-deoxyuridine (EdU) staining and cell counting kit-8 (CCK-8). Quantitative Real Time Polymerase Chain Reaction (PCR) was applied to detect the messenger RNA (mRNA) expression of inflammatory factors interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) in chondrocytes. Also, Western blot was adopted to detect the differential expression of NF-κB pathway-related proteins NF-κB and matrix metalloproteinase 13 (MMP-13).

Compared with that in normal cartilage tissues, miR-27a in OA cartilage tissues was decreased evidently (p<0.05). The expression level of miR-27a was higher in miR-27a mimics group than in control group, while it significantly declined in miR-27a inhibitor group (p<0.05). EdU staining and CCK-8 method results showed that miR-27a mimics could promote the proliferation of chondrocytes, while miR-27a inhibitor inhibited the proliferation of chondrocytes. Compared with those in control group, the expression levels of inflammatory factors TNF-α and IL-6 in chondrocytes in miR-27a inhibitor group were increased significantly (p<0.05). MiR-27a mimics could evidently reduce the expression of inflammatory factor IL-6 (p<0.05), but did not significantly reduce the expression of TNF-α. Besides, the results of Western blot suggested that the expression levels of MMP-13 and NF-κB proteins were decreased significantly in miR-27a mimics group (p<0.05) and increased significantly in miR-27a inhibitor group (p<0.05).

MiR-27a in OA cartilage tissues is evidently lower than in normal cartilage tissues. Transfection of miR-27a mimics can promote proliferation of chondrocytes, lower the expression of inflammatory factors, and reduce the expression of MMP-13 and NF-κB proteins. Therefore, the up-regulation of miR-27a can benefit the treatment of bone joints through the NF-κB pathway.