胱硫醚γ-裂解酶产生的内源性硫化氢对脂多糖诱导大鼠肝细胞凋亡的调节作用

Cystathionine-γ-iyase-derived hydrogen sulfide regulate LPS-induced apoptosis of the rat hepatic BRL cell line in vitro

目的探讨内源性胱硫醚γ-裂解酶（CSE）/硫化氢（H2S）体系在脂多糖（LPS）诱导的肝细胞凋亡中的调节作用。方法培养大鼠正常肝细胞系BRL。实验随机分组为溶剂对照组、siRNA阴性对照组、CSEsiRNA组、LPS组、CSEsiRNA＋LPS组。设立时间点为0h、4h、12h、24h；每组4个平行样。通过LPS孵育大鼠肝细胞系BRL不同时间，造成细胞损伤模型，以培养液上清中LDH活性反映细胞损伤程度。通过RT—PCR与Westernblot检测CSE基因、蛋白表达，用去蛋白法检测H2S生成情况；应用RNAi干扰技术，成功转染CSEsiRNA于肝细胞中，降低LPS引起的内源性H2S生成增多。通过荧光染色法检测BRL细胞线粒体膜电位（MMP）变化，通过Westernblot检测胞浆细胞色素c蛋白表达变化，应用流式细胞术检测BRL细胞凋亡率变化情况。结果LPS可显著提高CSE基因、蛋白的表达，并使H2S生成增多。同时也可使MMP降低并导致细胞凋亡率的增加。通过RNAi干扰技术，成功转染CSEsiRNA于肝细胞系BRL中，降低LPS引起的内源性H2S生成增多。与LPS单独作用BRL细胞相比，LPS作用转染后BRL细胞可导致MMP在短时间点降低，而在长时间点出现逐渐增加趋势；相应的细胞凋亡率则出现相反的趋势。结论在LPS诱导的细胞凋亡过程中，内源性CSE／H2S体系表现为早期抑制凋亡，晚期促进凋亡的特点。

Objective To explore Hydrogen sulfide （H2S）＇ s effect, a novel and important gaseous transmitter with diverse physiological activities which is generated in mammalian tissues mainly by Cystathionine-γ-lyase （CSE）, on lipopolysaecharide （LPS）-induced rat hepatocyte apoptosis. Methods BRL cells were cultured, and divided into control group, siRNA group, CSE siRNA group, LPS group, CSE siRNA＋ LPS group. The damaged cell modules of LPS breeded liver BRL were created, and observed and evaluated at 0, 4, 12, and 24 hrs. Results The distributions of these enzymes were species-or tissue-specific. The liver, as the main organ that generated H2S in vivo, functioned in biotransformation and metabolism. However, the liver was vulnerable to damage from internal and external factors such as inflammatory mediators, drugs and poisons. This study evaluated the endogenous CSE/H2S synthesis regulating LPS-indueed apoptosis of hepatic cells. The rat hepatic cell line BRL was incubated with LPS for different times to establish a cell damage model. Incubation with LPS resulted in a significant increase in CSE expression and H2S production. It also decreased the mitochondrial membrane potential （MMP） and stimulated apoptosis. Pretreatment with the CSE siRNA decreased LPS-enhanced H2S production. Interestingly, apoptosis increased for a short time and thendecreased gradually, while the MMP showed the opposite trend. Conclusion These results indicate that endogenous CSE/H2S synthesis exhibits early anti-apoptotic activity and subsequent pro-apoptotic activity in LPS-induced apoptosis. This could suggest a new approach for developing novel drugs for this condition.