Abstract 14071: Gut Microbial Metabolite Trimethylamine N-oxide Enhances Endoplasmic Reticular Stress and Promotes Endothelial Dysfunction

Abstract

Background: The intestinal microbe-derived metabolite trimethylamine N-oxide (TMAO) is known to the increase risk of cardiovascular diseases (CVDs). Endothelial dysfunction is associated with most forms of CVDs and is characterized by damage to the endoplasmic reticulum (ER). The current study was aimed to investigate the involvement of endoplasmic reticulum stress (ERS)-mediated protein kinase R-like endoplasmic reticulum kinase (PERK) signaling in TMAO induced endothelial dysfunction. Methods and Results: Biochemical analysis showed that PERK, CHOP, IRE-1α, AFT-4, eIF2 α which are indicative of ER stress, increased significantly in a dose dependent manner in response to TMAO treatment in endothelial cells. Western blot and immunofluorescent analysis showed significant increase in the phosphorylation of PERK and eIF2α along with upregulation of CHOP, IRE-1α and AFT-4 in TMAO group (30μM) compared to the control group (n=4/group; p<0.05). TMAO (30μM) treatment for 24h induced mitochondrial dysfunction as evidenced by decreased mitochondrial membrane potential, increased mitochondrial ROS levels, and also enhanced endothelial cell permeability compared to the control (n=6/group; p<0.05) . Furthermore, treatment with a PERK inhibitor (GSK2606414, 50nM, 24h) inhibited TMAO-induced phosphorylation of ER stress-related proteins, PERK and eIF2α and downregulated IRE1α, AFT-4 and CHOP and protected against increased endothelial cell permeability and mitochondrial ROS production. Conclusion: Our findings suggest that TMAO induced endothelial dysfunction through the ER stress-mediated PERK- eIF2 α -ATF4signaling pathway. Treatment with PERK inhibitors like (GSK2606414) could be a novel therapeutic strategy in TMAO-induced endothelial dysfunction.