Epigallocatechin-3-O-gallate promotes extracellular matrix and inhibits inflammation in IL-1β stimulated chondrocytes by the PTEN/miRNA-29b pathway

Context Epigallocatechin-3-O-gallate (EGCG) exhibits anti-arthritic activity. MiR-29b-3p provokes chondrocyte apoptosis and promotes the initiation and development of osteoarthritis (OA). Objective To explore the roles of EGCG and miR-29b-3p in interleukin-1 beta (IL-1 beta)-stimulated chondrocytes. Materials and methods HE and Safranin O staining were used to detect the pathological changes of cartilage tissue in OA patients and healthy people. OA-like chondrocyte injury was mimicked by 5 ng/mL IL-1 beta stimulation for 24 h in vitro, and after transfection with miR-29b-3p mimics and pcDNA-PTEN, IL-1 beta-stimulated chondrocytes were pre-treated with EGCG (20 and 50 mu M) for 2 h. Cell viability, colony numbers, apoptosis rate, the levels of IL-6 and matrix metalloproteinase-13 (MMP-13), miR-19b-3p, PTEN and apoptosis-associated proteins in chondrocytes were evaluated. Results MiR-29b-3p level was upregulated in cartilage tissues of OA patients (3.5-fold change, p < 0.001) and IL-1 beta stimulated chondrocytes (two fold change, p < 0.001). The matrix staining was weakened and unevenly distributed, and the chondrocytes were arranged disorderly in the tissues of patients with OA. EGCG (20 and 50 mu M) increases viability and decreases the levels of miR-29b-3p and MMP-13 and IL-6 in IL-1 beta stimulated chondrocytes (p < 0.05). MiR-29b-3p mimics reversed the effects above 50 mu M EGCG (p < 0.05). Furthermore, PTEN overexpression abrogated the effects of miR-29b-3p mimics on viability, colony numbers, apoptosis rate and the levels of Bcl-2, MMP-13, IL-6, Bax and cleaved caspase 3 in IL-1 beta-stimulated chondrocytes (p < 0.01). Discussion and conclusions EGCG is a potential candidate for the treatment of OA, which also can be explored in a novel therapeutic method for other degenerative or inflammatory disorders.