Could oxidative stress regulate the expression of microRNA-146a and microRNA-34a in human osteoarthritic chondrocyte cultures?

Oxidative stress and the overproduction of reactive oxygen species (ROS) play an important role in the pathogenesis of osteoarthritis (OA). Accumulating evidence has demonstrated the involvement of microRNAs (miRNAs) dysregulation in disease development and progression. In this study, we evaluated the effect of oxidative stress on miR-146a and miR-34a expression levels in human OA chondrocytes cultures stimulated by H2O2. Mitochondrial ROS production and cell apoptosis were detected by flow cytometry. The antioxidant enzymes SOD-2, CAT, GPx, the transcriptional factor NRF2 and the selected miRNAs were analyzed by qRT-PCR. The H2O2-induced oxidative stress was confirmed by a significant increase in superoxide anion production and of the apoptotic ratio. Furthermore, H2O2significantly up-regulated the expression levels of SOD-2, CAT, GPx and NRF2, and modulated miR-146a and miR-34a gene expression. The same analyses were carried out after pre-treatment with taurine, a known antioxidant substance, which, in our experience, counteracted the H2O2-induced effect. In conclusion, the induction of oxidative stress affected cell apoptosis and the expression of the enzymes involved in the oxidant/antioxidant balance. Moreover, we demonstrated for the first time the modification of miR-146a and miR-34a in OA chondrocytes subjected to H2O2stimulus and we confirmed the antioxidant effect of taurine.