P38 MAPK信号通路在金黄色葡萄球菌诱导U937细胞凋亡中的作用

Involvement of the p38 mitogen activated protein kinase signal pathway in Staphylococcus aureus-induced apoptosis of human monocyte U937 cells

目的建立金黄色葡萄球菌(Staphylococcus aureus)诱导人巨噬细胞系U937细胞凋亡模型,探讨p38 MAPK信号转导通路在此凋亡过程中的作用。方法采用Annexin V FITC/PI双染流式细胞仪检测金黄色葡萄球菌感染不同时间时U937细胞的凋亡率;利用Western blotting检测p38MAPK的磷酸化水平;预先用不同浓度的SB203580(p38 MAPK途径抑制剂)处理U937细胞,采用Annexin V FITC/PI双染分析感染30min后U937细胞的凋亡情况。结果金黄色葡萄球菌可以诱导U937细胞凋亡,并且随着感染时间的延长,细胞凋亡率也逐渐增高。p38 MAPK在加入金黄色葡萄球菌15min后表达明显增高,30min时达高峰,随后,逐渐降低。总的p38 MAPK水平在整个实验期间内几乎无变化。用SB203580抑制p38 MAPK通路,引起抑制剂浓度依赖性的细胞凋亡率降低。结论金黄色葡萄球菌呈时间依赖性诱导U937细胞凋亡,p38 MAPK信号转导通路的激活在金黄色葡萄球菌诱导的U937细胞凋亡过程中起到了重要的作用。

To establish a apoptotic model of human monocyte U937 cells induced by Staphylococcus aureus used to investigate the role of the p38 mitogen activated protein kinase （MAPK） signal pathway in this apoptotic process, the U937 cell line was pre-treated with different concentrations of SB203580（an inhibitor of p38 MAPK pathway） and the apoptotic rate of U937 cells was determined using Annexin V-FITC and propidium iodide（PI） double staining and flow cytometry （FCM） 30 minutes after infection with S. aureus. The level of phosphorylation on p38 MAPK was tested by Western blotting. It was found that S. aureus could induce apoptosis of the cultured U937 cells in a time-dependent manner, in which the phosphorylation of p38 protein was found in 15 minutes ,the maximal phosphorylation occurred in 30 minutes and began to decline 60 minutes after infection. In contrast, the lex, el of the total p38 protein was not changed in the whole course of experiment. When the p38 MAPK signal pathway was inhibited by SB203580, the rate of the inhibitor concentration-dependent apoptosis of U937 cells was reduced. These results indicate that S. aureus can induce apoptosis of the cultured U937 cells in a time-dependent manner, and the activation of the p38 MAPK signal pathway by S. aureus appears to be the main way to mediate apoptosis.