ERK对慢性哮喘大鼠气道平滑肌细胞凋亡的影响

The effect of ERK signaling pathway on cell apoptosis in airway smooth muscle cells of chronic asthmatic rats

目的：探讨细胞外信号调节蛋白激酶（ERK）通路在慢性哮喘大鼠气道平滑肌细胞（ASMC）凋亡中的作用及其机制。方法：30只Wistar大鼠分为正常对照组（A组）和慢性哮喘组（B组），用原位末端标记法和Annexin—V FIT CPI双染色法观察ASMC凋亡，免疫组织化学法检测bcl-2和bax的表达，Western blot检测caspase-3蛋白的表达，并用ERK激动剂表皮生长因子（EGF）和抑制剂PD98059干预两组ASMC，观察上述指标的变化。结果：与正常对照组ASMC比较，慢性哮喘组ASMC凋亡指数、早期凋亡细胞百分率明显下降。经PD98059干预之后，慢性哮喘组ASMC的凋亡指数与早期凋亡细胞百分率、bax蛋白表达量和caspase-3蛋白含量明显增高，bcl-2蛋白表达量明显降低。经EGF干预之后，慢性哮喘组ASMC凋亡指数与早期凋亡细胞百分率进一步下降，而这一作用可以被PD98059所抑制。结论：慢性哮喘组大鼠ASMC内源性增殖活性增加的同时，伴有凋亡活性下降。ERK1／2参与慢性哮喘ASMC凋亡调控，其机制与bcl-2家族和caspace-3有关。

AIM： To investigate the effect of ERK signaling pathway on apoptosis of airway smooth muscle cells （ASMCs） in chronic asthmatic rats. METHODS： Thirty Wistar rats were assigned to two groups： control group （A group, n = 15） and chronic asthmatic group （ B group, n = 15）. The apoptosis of ASMCs were detected by Situ end labeling and Annexin-V FITC PI double staining. The expressions of bcl-2 and bax were detected by immunocytochemical staining. The levels of caspase-3 protein were detected by Western blot. ASMC were treated with ERK activator epidermal growth factor （EGF） and inhibitor PD98059. RESULTS： Compared with control group, the apoptotic index and the percentage of the early apoptotic cells in ASMC from chronic asthmatic group were significantly decreased. After treatment with PD98059, the apoptotic index, the percentage of the early apoptotic cells, the expression of bax and the expression of caspase-3 protein in ASMC from chronic asthmatic group were significantly increased, and the expression of bcl-2 in ASMC from chronic asthmatic group were significantly decreased. Compared with those before treatment, apoptotic index and the percentage of the early apoptotic cells were significantly increased in EGF-treated cells. PD98059 could markedly inhibit the effect of EGF. CONCLUSION： Apoptotic activation is significantly decreased in ASMC from chronic asthmatic group while the endogenous proliferation activation is significantly increased. The regulation of cell apoptosis is possibly related to ERK signaling pathway. The bcl-2 family and caspase-3 may participate in the regulation mechanism of cell apoptosis by ERK signaling pathway in ASMC from chronic asthmatic group.