Xunrong Zhuang#, Lijiang He


Department of Orthopedics, the Second Affiliated Hospital of Fujian Medical University, Quanzhou 362000, China


Objective: This study aimed to investigate effects of miR-146a-5p on osteoarthritis inflammation and apoptosis of chondrocytes by down-regulating Smad4 expression. 

Methods: Osteoarthritis (OA) rat models were established by accessory ligament resection. OA chondrocytes and primary chondrocytes were isolated and cultured. Quantitative real-time fluorescence quantitative PCR (qRT-PCR) was used to detect the expressions of miR-146a-5p and Smad4 mRNA. ELISA was used to detect the expressions of inflammation-related factors IL-6 and TNF-α. Western blotting was used to detect the expressions of Smad4 and TGF-β protein. Flow cytometry was used to detect the apoptosis rate. Compared with rats from the control group and sham operation group, miR-146a-5p in cartilage tissue of rats from OA group was significantly down-regulated, and the expressions of Smad4 mRNA, inflammation-related factors IL-6 and TNF-α were significantly up-regulated (P <0.05). 

Results: Bioinformatics prediction and subsequent experiments proved that Smad4 was a direct target of miR-146a-5p. Compared with cells from the blank control group, the expressions of miR-146a-5p and TGF-β protein in cells of OA control group and OA+miR-NC group were significantly down-regulated, Smad4 protein was significantly up-regulated, and apoptosis rate of chondrocytes was significantly increased (P<0.05). miR-146a-5p and TGF-β protein in OA+miR-146a-5p mimics group were significantly up-regulated, and Smad4 protein and cell apoptosis rate were significantly down-regulated (P<0.05). miR-146a-5p is in a low expression state in OA cartilage tissue. 

Conclusion: Overexpression regulation of miR-146a-5p can effectively reduce inflammatory response and inhibit cell apoptosis, and the mechanism may be realized through down-regulation of Smad4.


miR-146a-5p, Smad4, Osteoarthritis, Chondrocytes.