Knockdown of LSD1 alleviates the IL-1β-induced chondrocyte apoptosis, inflammation and ECM degradation via TRIM32-mediated autophagy
Abstract Osteoarthritis (OA) is a common joint disease with characteristics of chronic inflammation and articular cartilage degeneration. It has been proved that LSD1 was up-regulated in OA cartilage tissues, but its role and regulatory mechanism in OA are unclear. Herein, interleukin 1 beta (IL-1β)-treated human chondrocytes was performed as a cell model of OA. Then, LSD1 expression was found that up-regulated in OA cartilage tissues and IL-1β-induced chondrocytes. Knockdown of LSD1 increased cell viability, while decreased apoptosis rate and inflammatory cytokines secretion levels in IL-1β-induced chondrocytes. In addition, knockdown of LSD1 reduced the expression of catabolic proteins (MMP-13 and ADAMTS-5) and enhanced the expression of anabolic proteins (Collagen II and Aggrecan) in chondrocytes after IL-1β stimulation. Moreover, overexpression of TRIM32 repressed chondrocyte viability, while promoted IL-1β-induced chondrocyte apoptosis, inflammation and ECM degradation. The expression of LSD1 and TRIM32 in OA cartilage was positively correlated, and knockdown of LSD1 down-regulated TRIM32 expression of chondrocytes. Our data further indicated that LSD1 regulated autophagy of chondrocytes through modulating TRIM32. Overexpression of TRIM32 reduced the effect of LSD1 knockdown on IL-1β-induced chondrocytes, while activating autophagy by Rapamycin further reversed this reduction. Therefore, our study shows that knockdown of LSD1 inhibited IL-1β-induced chondrocyte apoptosis, inflammation and ECM degradation via TRIM32-mediated autophagy.