Background Although it is recognized that bronchial smooth muscle cells （BSMCs） play a key role. in airway remodeling during chronic asthma, it is not well understood how BSMCs exert their inflammatory functions. The extracellular signal-regulated kinase 1/2 （ERK1/2） signaling pathway is an important signaling pathway in chronic asthma but its influence on secretion by BSMCs has not been well-studied. We investigated the impact of ERK1/2 signaling pathway on secretion by BSMCs in a rat model of chronic asthma in this study. Methods To create a rat model of chronic asthma, Wistar rats underwent ovalbumim （OVA） injection and eight weeks of inhalation. BSMCs were isolated and cultured in vitro. Epidermal growth factor, PD98059 and ERK1/2 antisense oligonucleotide were used to explore the role of ERK1/2 signaling pathway. The expression of P-ERK1/2 （phospho-ERK1/2） in BSMCs was analyzed by Western blot and reverse transcriptase-polymerase chain reaction （RT-PCR）. Secretion of BSMCs was detected by enzyme-linked immunosorbent assay （ELISA）. Results Phospho-ERK1/2 expression was increased in BSMCs of chronic asthmatic rats compared with the controls. PD98059 inhibited expression of phospho-ERK1/2 protein, while treatment with an antisense oligonucleotide inhibited the expression of P-ERK1/2 mRNA and protein. BSMCs obtained from the chronic asthma group secreted significantly greater quantities of growth factors （transforming growth factor （TGF）-β1, vascular endothelial growth factor （VEGF） and connective tissue growth factor （CTGF））, cytokines （regulated upon activation, normal T cell-expressed and secreted （RANTES） and eotaxin）, and extracellular matrix （fibronectin and collagen I） compared with normal controls. Epidermal growth factor stimulated secretion in both groups, but the response of the chronic asthma group was more intense. Both PD98059 and antisense oligonucleotide suppressed secretion by BSMCs in chronic ashmatic rats. Antisense oligonucleotide reduced t
XIE Min LIU Xian-sheng XU Yong-jian ZHANG Zhen-xiang BAI Jing NI Wang CHEN Shi-xin
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。
