Vildagliptin inhibits high free fatty acid (FFA)-induced NLRP3 inflammasome activation in endothelial cells

Abstract

Elevated free fatty acids (FFAs) are a risk factor for type 2 diabetes. Endothelial dysfunction induced by high levels of FFAs is one of the mechanisms related to the progression of diabetes. In clinical diabetes care, DPP-4 inhibitors have been shown to be effective in reducing glucose levels. In this study, we investigated the molecular mechanism of the clinically available DPP-4 inhibitor vildagliptin in the protection of FFA-induced endothelial dysfunction. Treatment of endothelial cells with vildagliptin inhibits FFA-induced cellular LDH release and generation of ROS. Vildagliptin also reverses FFA-induced reduced levels of GSH and elevated expression of the FFA-associated NAPHD oxidase protein NOX-4. Moreover, vildagliptin ameliorates the reduction in mitochondrial potential triggered by FFAs. Mechanistically, we show that vildagliptin suppresses FFA-induced expression of proteins of the NLRP3 inflammasome complex, including NLRP3, ASC, p20 and HMGB-1, and mitigates FFA-induced inactivation of the AMPK pathway. Consequently, vildagliptin inhibits production of two cytokines that are favored by NLRP3 inflammasome machinery: IL-1β and IL-18. Finally, we demonstrate that vildagliptin ameliorates FFA-induced reduced eNOS, indicating its protective role against endothelial dysfunction. Collectively, we conclude that the protective role of vildagliptin in endothelial cells is mediated via suppression of the AMPK-NLRP3 inflammasome-HMGB-1 axis pathway. These findings imply that the anti-diabetic drug vildagliptin possesses dual therapeutic applications in lowering glucose and improving vascular function.

Keywords: AMPK; HMG-1; NLRP3 inflammasome; Vildagliptin; free fatty acids (FFAs).