Administration of metformin alleviates atherosclerosis by promoting H2S production via regulating CSE expression

Abstract

The therapeutic effect of metformin (Met) on atherosclerosis was studied here.Effects of methionine and Met on the induction of inflammatory response and H 2 S expression in peritoneal macrophages were evaluated. Enzyme-linked immunosorbent assay, immunohistochemistry assay, western blot, and quantitative reverse transcription polymerase chain reaction were conducted to observe the levels of cystathionine γ-lyase (CSE), DNA methyltransferases 1 (DNMT1), DNMT3a, DNMT3b, tumor necrosis factor (TNF-α), interleukin 1b (IL-1β), and hydrogen sulfide (H 2 S). Luciferase and bisulfite sequencing assays were also utilized to evaluate the CSE promoter activity as well as the methylation status of CSE in transfected cells. Methionine significantly elevated Hcy, TNF-a, H 2 S, and IL-1β expression while decreasing the level of CSE in C57BL/6 mice. In contrary, co-treatment with Methionine and Met reduced the detrimental effect of Methionine. Homocysteine (Hcy) decreased H 2 S expression while promoting the synthesis of IL-1β and TNF-α in THP-1 and raw264.7 cells. Treatment of THP-1 and raw264.7 cells with methionine and Met reduced the activity of methionine in dose dependently. Moreover, Hcy increased the expression of DNMT and elevated the level of methylation in the CSE promoter, whereas the co-treatment with methionine and Met attenuated the effects of Hcy. Methionine significantly decreased plasma level of CSE while increasing the severity of inflammatory responses and plasma level of Hcy, which in turn suppressed H 2 S synthesis and enhanced DNA hypermethylation of CSE promoter to promote the pathogenesis of atherosclerosis. In contrary, co-treatment with methionine and Met reduced the detrimental effect of methionine.

Metformin, Macrophage Dysfunction and Atherosclerosis

“…In THP-1 and raw264.7 cells, Hcy up-regulated the expression of DNA methyltransferase and increased the CSE promoter methylation. Whether in mice or in macrophages, metformin treatment can reduce the deleterious effects of methionine, which provides new insights into the actions of metformin to inhibit AS ( 63 ).…”

The role of hydrogen sulphide signalling in macrophage activation

“…Indeed, some commonly prescribed drugs have already been indicated to affect endogenous H 2 S signalling pathway. For example, statins are able to modulate H 2 S metabolism 77,78 in the cardiovascular system, while the well‐known antidiabetic drug, metformin, could promote H 2 S production by elevating CSE 79 . These discoveries prompt us to rescrutinize the ‘new function of old drugs’ while pursuing for novel H 2 S regulating compounds in the future investigations.…”

p-Cymene Modulate Oxidative Stress and Inflammation in Murine Macrophages: Potential Implication in Atherosclerosis

“…increased inflammation. Association of increased TNF-α gene expression and plasma levels in with atherosclerosis and cardiovascular disease is well documented [ 26 - 29 ]. TNF-α is an acute phase reaction gene that is secreted mainly by macrophages in response to inflammation-inducing stimuli.…”