MIR-449A TARGETS GDF5 TO REGULATE APOPTOSIS AND PROLIFERATION OF OSTEOARTHRITIS CELLS INDUCED BY IL-1 Β

Lin Chen, Bo Li, Haibo Wang, Guangyu Wu, Shixiong He, Shengqiang Ran, Fan Yang^*

Department of Orthopedics, Chongqing Red Cross Hospital (People's Hospital of Jiangbei District), Chongqing 400020, PR China

Objective: Analyze the apoptosis and proliferation of osteoarthritis cells induced by microRNA-44A (Mir-449a) targeting the growth differentiation factor 5 (GDF5) and regulating interleukin-1β (IL-1β). 

Methods: The treatment results of sixty eight patients with osteoarthritis who underwent operations in our hospital were analyzed. According to the X-ray findings of the knee joint and the severity of osteoarthritis, they were divided into grades 0 through 4: 23 normal cartilage tissue (grade 0), 18 medium-term cartilage tissue (grade 3), and 27 advanced cartilage tissue (grade 4). The expression levels of mir-449a and GDF5 in cartilage tissue were measured. SW1353 cells were cultured and transfected with lentivirus. The cells were divided into a control group (cultured in normal medium), into group IL-1 β (incubated with 200 nm IL-1 β 2 in normal medium for 24 h), and into group shmir-449a + IL-1 β (adding 10 ng/ml IL-1 β to the culture medium after transfection of shmir-449a). At least four parallel controls were set in each group. Cell proliferation, apoptosis, and the expression of mir-449a, GDF5, type II collagen (CO Ⅱ), aggrecan, matrix metalloproteinase-13 (MMP-13), and platelet reactive protein, disintegrin metallopeptidase-4 (ADAMTS-4) were measured. 

Results: Compared with normal cartilage tissue, the expression of mir-449a and GDF5 in metaphase cartilage tissue was significantly increased and GDF5 expression level was significantly decreased (p<0.05); compared with medium-term cartilage tissue, mir-449a expression level was significantly increased and GDF5 expression level was significantly decreased (p<0.05). Compared with the control group, the cell survival rate and the expression levels of GDF5, Co Ⅱ and aggrecan in IL-1 β group were significantly decreased and the apoptosis rate and the expression levels of mir-449a, MMP-13 and ADAMTS-4 were significantly increased (p<0.05); compared with the IL-1 β group, the cell survival rate and the expression levels of GDF5, Co Ⅱ and aggrecan were significantly increased in the IL-1 β group, while the apoptosis rate and the expression levels of mir-449a, MMP-13 and ADAMTS-4 were significantly increased and significantly decreased, respectively (p<0.05). 

Conclusion: Down-regulation of mir-449a expression may promote the proliferation of osteoarthritis cells induced by IL-1 β and inhibit the apoptosis of osteoarthritis cells induced by IL-1 β by promoting the expression of GDF5.