Hydrogen sulfide lowers hyperhomocysteinemia dependent on cystathionine γ lyase S‐sulfhydration in ApoE‐knockout atherosclerotic mice

Abstract

Background and Purpose Hydrogen sulfide donors can block the cardiovascular injury of hyperhomocysteinemia. H 2 S also lowers serum homocysteine in rats with mild hyperhomocysteinemia, but the pharmacological mechanism is unknown. The present study investigated the mechanism(s) involved. Experimental Approach ApoE‐knockout mice were fed a Paigen diet and L‐methionine in drinking water for 16 weeks to create a mouse model of atherosclerosis with hyperhomocysteinemia. H 2 S donors (NaHS and GYY4137) were administered by intraperitoneal injection. We also assayed the H 2 S produced (by methylene blue assay and mito‐HS [H 2 S fluorescence probe]), cystathionine γ lyase (CSE) mRNA and protein expression, and CSE sulfhydration and nitrosylation and its activity. Key Results H 2 S donor treatment significantly lowered atherosclerotic plaque area, macrophage infiltration, and serum homocysteine level in the mouse model of atherosclerosis with co‐existing hyperhomocysteinemia. mRNA and protein levels of CSE, a key enzyme catalyzing homocysteine trans‐sulfuration, were down‐regulated with hyperhomocysteinemia, and CSE catalytic activity was inhibited. All these effects were reversed with H 2 S donor treatment. Hyperhomocysteinemia induced CSE nitrosylation, whereas H 2 S sulfhydrated CSE at the same cysteine residues. Nitrosylated CSE decreased and sulfhydrated CSE increased its catalytic and binding activities towards L‐homocysteine. Mutation of C252, C255, C307, and C310 residues in CSE abolished CSE nitrosylation or sulfhydration and prevented its binding to L‐homocysteine. Conclusions and Implications Sulfhydration or nitrosylation of CSE represents a yin/yang regulation of catalysis or binding to L‐homocysteine. H 2 S donor treatment enhanced CSE sulfhydration, thus lowering serum L‐homocysteine, which contributed in part to the anti‐atherosclerosis effects in ApoE‐knockout mice with hyperhomocysteinemia.

Role of Endothelial Dysfunction in Cardiovascular Diseases: The Link Between Inflammation and Hydrogen Sulfide

“…In recent years, considerable evidence indicates that the downregulated CSE/H2S pathway plays a pathophysiologic role in the development of atherosclerosis (Kanagy et al, 2017;Fan et al, 2019). CSE-knockout mice fed with atherogenic diet exhibt more severe atherosclerosis, suggesting that the disturbed CSE/ H2S pathway predisposes the animals to the development of atherosclerosis (Mani et al, 2013).…”

Metabolism of vascular smooth muscle cells in vascular diseases

“…Increased cysteine contributes to inflammation, oxidative stress, and proliferation and migration of VSMCs (70). Endogenous hydrogen sulfide (H 2 S) is mainly produced from cysteine, and all of the synthesizing enzymes of H 2 S are expressed in VSMCs (22).…”

Clinical Use of Hydrogen Sulfide to Protect Against Intimal Hyperplasia

“…Many studies report anti-inflammatory properties of H 2 S, in particular in the context of atherosclerosis and cardiac failure [for full review see Pan et al ( 97 )]. Thus, H 2 S reduces adhesion and infiltration of pro-inflammatory cells and circulating levels of pro-inflammatory chemokines and cytokines in the ApoE –/– mouse model of atherosclerosis ( 98 , 99 ). Similarly, several reports document that H 2 S donors (NaHS, DATS, SG1002, STS) or CSE overexpression decrease leukocyte and neutrophil infiltration and cytokine production following ischemic injury in various models of myocardial infarction ( 100 – 105 ).…”