Bourque Caitlyn, Zhang Yanjie, Fu Ming, Racine Mélanie, Greasley Adam, Pei Yanxi, Wu Lingyun, Wang Rui, Yang Guangdong
Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Canada; Cardiovascular and Metabolic Research Unit, Laurentian University, Sudbury, Canada.
Cardiovascular and Metabolic Research Unit, Laurentian University, Sudbury, Canada; School of Life Science, Shanxi University, Taiyuan, China.
Toxicol Appl Pharmacol. 2018 Jan 1;338:20-29. doi: 10.1016/j.taap.2017.11.004. Epub 2017 Nov 8.
Hydrogen sulfide (HS) is a novel gasotransmitter and acts as a multifunctional regulator in various cellular functions. Past studies have demonstrated a significant role of HS and its generating enzyme cystathionine gamma-lyase (CSE) in the cardiovascular system. Lipopolysaccharide (LPS), a major pathogenic factor, is known to initiate the inflammatory immune response. The cross talk between LPS-induced inflammation and the CSE/HS system in vascular cells has not yet been elucidated in detail. Here we showed that LPS decreased CSE mRNA and protein expression in human endothelial cells and blocked HS production in mouse aorta tissues. Transfection of the cells with TLR4-specific siRNA knockdown TLR4 mRNA expression and abolished the inhibitory role of LPS on CSE expression. Higher dose of LPS (100μg/ml) decreased cell viability, which was reversed by exogenously applied HS at physiologically relevant concentration (30μM). Lower dose of LPS (10μg/ml) had no effect on cell viability, but significantly induced inflammation gene expressions and cytokines secretion and stimulated cell hyper-permeability. HS treatment prevented LPS-induced inflammation and hyper-permeability. Lower VE-cadherin expression in LPS-incubated cells would contribute to cell hyper-permeability, which was reversed by HS co-incubation. In addition, HS treatment blocked LPS-induced NFκB transactivation. We further validated that LPS-induced hyper-permeability was reversed by CSE overexpression but further deteriorated by CRISPR/Cas9-mediated knockout of CSE. In vivo, deficiency of CSE sensitized the mice to LPS-induced inflammation in vascular tissues. Take together, these data suggest that CSE/HS system protects LPS-induced inflammation and cell hyper-permeability by blocking NFκB transactivation.
硫化氢（HS）是一种新型气体信号分子，在多种细胞功能中发挥多功能调节作用。过去的研究表明，HS及其生成酶胱硫醚γ-裂解酶（CSE）在心血管系统中具有重要作用。脂多糖（LPS）是一种主要的致病因素，已知可引发炎症免疫反应。LPS诱导的炎症与血管细胞中CSE/HS系统之间的相互作用尚未得到详细阐明。在此，我们发现LPS降低了人内皮细胞中CSE的mRNA和蛋白表达，并阻断了小鼠主动脉组织中HS的产生。用TLR4特异性siRNA转染细胞可降低TLR4 mRNA表达，并消除LPS对CSE表达的抑制作用。高剂量LPS（100μg/ml）降低细胞活力，而生理相关浓度（30μM）的外源性HS可逆转这种作用。低剂量LPS（10μg/ml）对细胞活力无影响，但显著诱导炎症基因表达和细胞因子分泌，并刺激细胞高通透性。HS处理可预防LPS诱导的炎症和高通透性。LPS处理的细胞中VE-钙黏蛋白表达降低会导致细胞高通透性，而HS共同孵育可逆转这种情况。此外，HS处理可阻断LPS诱导的NFκB反式激活。我们进一步验证，CSE过表达可逆转LPS诱导的高通透性，而CRISPR/Cas9介导的CSE基因敲除则会使其进一步恶化。在体内，CSE缺乏使小鼠对LPS诱导的血管组织炎症敏感。综上所述，这些数据表明，CSE/HS系统通过阻断NFκB反式激活来保护细胞免受LPS诱导的炎症和细胞高通透性。
