24-LB: RIPK1 Activation Induces Necroptosis, Proinflammation, and Profibrosis in Kidney of STZ/HFD-Induced Diabetic Mice

Diabetic kidney disease (DKD) is attributed largely to renal tubular interstitial fibrosis. However, the complex mechanism of renal tubular interstitial fibrosis in DKD pathogenesis remains unclear. Recently, necroptosis has emerged as an important cell death model in many pathological conditions, which is regulated through RIPK1/RIPK3 pathway. In this present study, we aimed to evaluate whether necroptosis is involved in the development of diabetic kidney disease, and to investigate the mechanisms involved. In the current study, the results of immunohistochemistry and Western blot showed that the ratio of p-RIPK1/RIPK1, p-RIPK3/RIPK3, p-MLKL/MLKL were significantly increased in the kidney of STZ/HFD induced diabetic mice. Additionally, the levels of serum MCP-1, and the expression of IL-1 β and TGF - β in kidney were increased in the diabetic mice. Moreover, Necrostatin-1, an inhibitor of RIPK1, can effectively decrease the ratio of p-RIPK1/RIPK1, p-RIPK3/RIPK3, p-MLKL/MLKL, the levels of serum MCP-1, and the expression of TGF-β and IL-1 β in kidney in the diabetic mice. Necrostatin-1 treatment also resulted in delayed progression of renal structural lesions and significantly improved the function of kidney. High glucose stimulation, which induced excessive ROS production, led to necrosis and increased phosphorylation of RIPK1, RIPK3 and MLKL in rat tubular epithelial cell NRK-52E cells. Moreover, NAC treatment, a ROS inhibitor, could partly reverse the effect of glucose on RIPK1, RIPK3, and MLKL.

In conclusion, RIPK1 activation may induce necroptosis, pro-inflammation and pro-fibrosis in kidney of STZ/HFD induced diabetic mice; High glucose induces RIPK1 -dependent necroptosis in NRK-52E cells; excessive ROS production mediate high glucose induced necroptosis.