The Acid Sphingomyelinase Inhibitor Amitriptyline Ameliorates TNF-α-induced Endothelial Dysfunction via the MAPK Signaling Pathway

Abstract Purpose Inflammation associated endothelial cell (ECs) dysfunction is key to atherosclerotic disease. The soluble endo-lysosomal protein, acid sphingomyelinase (ASMase) plays a crucial role in atherosclerosis. However, the mechanism by which ASMase regulates the inflammatory reaction in ECs remains unknown. Numerous studies have demonstrated that in addition to the antidepressant effects, amitriptyline can also effectively inhibit ASMase. Thus, the aim of this study was to investigate whether the effects of amitriptyline protect against inflammation in TNF-α-induced ECs. Methods HUVEC were pre-incubated with 2.5 µM amitriptyline (1 h) and subjected to 23 h TNF-α (20 ng/ml). EdU, tube formation, transwell and monocyte adhesion assay were performed to investigate the endothelium function. Vascular tone measurement was used to detected endothelial-dependent relaxation in mice. Protein levels of ICAM-1, VCAM-1, MCP-1, MAPK and NF-κB were detected using western blot. Results We demonstrated that preconditioning with the amitriptyline down-regulated TNF-α-induced expression of proinflammatory proteins including ICAM-1, VCAM-1, and MCP-1 in ECs, as well as the secretion of sICAM-1 and sVCAM-1. Additionally, we demonstrated that amitriptyline suppressed TNF-α-induced MAPK phosphorylation as well as the activity of NF-κ B in HUVEC. Results also indicated that with treatment of TNF-α, the aorta of ASMase−/− mice showed elevated endothelial-dependent relaxation compared to wild-type counterparts. Conclusion These results suggest that the AMI reduces endothelial inflammation, consequently improving vascular endothelial function. This study showed that amitriptyline might protect ECs from TNF-α-induced inflammation. Thus, identification of amitriptyline as a potential strategy to reverse endothelial function is of importance to preventing vascular diseases.