Toll样受体2在分枝杆菌诱导巨噬细胞凋亡中的作用

目的建立分枝杆菌感染巨噬细胞的模型,探讨Toll样受体2(TLR2)在分枝杆菌诱导巨噬细胞凋亡中的作用。方法使用豆蔻酰佛波醇乙酯(PMA)诱导U937细胞分化使之具有吞噬能力,分别用胞内分枝杆菌(M.intracellulare)、结核分枝杆菌(MTB)、脓肿分枝杆菌(M.abscessus)感染已分化的U937细胞,于感染后0、4、8、24、48和72h提取细胞,用流式细胞仪检测u937细胞凋亡率及细胞膜TLR2的表达,Western blot检测U937细胞感染后72 h时细胞内总TLR2的含量,并观察阻断TLR2后U937细胞感染分枝杆菌后的凋亡变化。结果 M.intracellulare M.abscessus感染U937细胞后的细胞凋亡率随时间的推移逐渐升高,4h后凋亡率已显著高于正常对照组,而MTB感染后的细胞凋亡率也有升高但与正常对照组差异无统计学意义;3种分枝杆菌感染U937细胞后的细胞凋亡率差异有统计学意义(P<0.05),由高到低的排列依次为M.abscessus、M.intracellulare和MTB。U937细胞的TLR2表达量在分枝杆菌感染后4 h内迅速升高,8 h后TLR2的含量稳定下来,不同分枝杆菌感染U937细胞后TLR2的表达并不相同(P<0.05),由高到低的排列依次为MTB、M.intracellulare和M.abscessus。阻断U937细胞的TLR2可以明显降低感染分枝杆菌后细胞的凋亡率。结论 TLR2并不直接引起巨噬细胞的凋亡,但TLR2在分枝杆菌诱导巨噬细胞凋亡中有重要作用。

The role of Toll-like receptor 2 in Mycobacterium-induced macrophage apoptosis

Objective To study the role of Toll-like receptor 2 （TLR2） in Mycobacterium induced apoptosis of rnacrophages. Methods U937 cells were cultured in vitro, and then phorbol myristate acetate （PMA） was added to induce U937 cells to phagocytosis. Functional U937 cells were infected with Mycobacterium intracellulare, Mycobacterium tuberculosiS （MTB） and MycobacteriuMabscessus. U937 cells in each group were extracted at 0 h, 4 h, 8 h, 24 h, 48 h, and 72 h time points. U937 cell apoptosis rate and the TLR2 in U937 cell membrane was detected with flow cytometry. TLR2 in U937 cells infected with Mycobacterium were detected with Western blot at 72 h time point. TLR2 of U937 ceils were blocked by anti-TLR2 monoclonal antibody. We used different Mycobacterium affect the U937 ceils. Then the apoptosis rate of U937 cells in which TLR2 were blocked was detected by flow cytornetry. Results Following infection with M. intracellulare, M. abscessus, the apoptosis of U937 cells increased. The apoptosis rate was significantly higher than normal control, while no difference was found between MTB group and normal control. At 72 h time point, the apoptosis rate of U937 of M. abscessus group was the highest, fol-lowed by M. intraceHulare group. MTB group was the lowest. After infection, the TI.R2 increased in 4 hours, and then maintained such level after 8 hours. Each k4ycobacteriuM induced different levels of TLR2. The TI.R2 of MTB group was higher than M. intracellulare group, which was higher than M. abscessus group. Blocking TLR2 decreasedthe apoptosis rate of U937 cells significantly after infection by mycobacterium for 72 h. Conclusions Infection of Mycobacterium could induce the apoptosis of macrophage. TLR2 is not involved in the apoptosis of macrophage directly. However, TLR2 is associated with the Mycobacterium induced apoptosis of maerophages.