Role of SIRT3-mediated IDH2 deacetylation in energy metabolism disorders and necroptosis of chondrocytes induced by T-2 Toxin.

To elucidate the role of Sirtuin 3 (SIRT3) / isocitrate dehydrogenase 2 (IDH2) axis in T-2 toxin-induced energy metabolism disorders and necroptosis in chondrocytes. Enrichment analysis was performed on differentially expressed genes in the articular cartilage and serum of Kashin-Beck disease patients. Sprague-Dawley rats were randomly divided into control (equal volume of normal saline), low T-2 toxin (100 ng/g·bw/day), and high T-2 toxin (200 ng/g·bw/day) groups. Human SW1353 cells were used to construct T-2 toxin exposed and SIRT3 intervened models in vitro. Enrichment analysis results indicated involvement of the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) in T-2 toxin-induced cartilage damage. The articular cartilage pathological changes including attenuated matrix staining, thinning of the cartilage layer, and blurred or disrupted marginal lines were observed in rats exposed to T-2 toxin. Western blot revealed that T-2 toxin downregulated SIRT3 expression and reduced the SIRT3-IDH2 interaction in chondrocyte. Immunoprecipitation confirmed decreased IDH2 deacetylation of chondrocyte induced by T-2 toxin. Additionally, the dose-dependently increased isocitrate content, while decreasing α-ketoglutarate and NADH levels of chondrocyte exposure to T-2 toxin. T-2 toxin also reduced activities of mitochondrial complexes II, III, and IV, inhibited oxygen consumption rate, and decreased adenosine triphosphate production of chondrocyte. Additionally, T-2 toxin upregulated necroptosis markers RIPK1, RIPK3, and MLKL, an effect reversed by a SIRT3 activator. In conclusion, T-2 toxin inhibited SIRT3 expression in chondrocytes, reduced IDH2 deacetylation, blocked the TCA cycle and OXPHOS, and ultimately led to energy metabolism disorder and necrosis of chondrocyte.