人肺泡型细胞A549在大肠埃希菌诱导下非特异性免疫分子的表达

Expression of nonspecific immunological molecules of A549 cells induced by E.coli

目的:呼吸道上皮细胞在呼吸道固有免疫应答中起重要作用,文中探讨呼吸道上皮细胞对大肠埃希菌(E.coli)的应激反应能力及其作用机制。方法:常规体外培养A549细胞,细胞传代24h后加入灭活的E.coli,进行不同浓度或时间的诱导;用半定量RT-PCR法检测其细胞中白细胞介素(IL)-6、补体C3和C-反应蛋白(CRP)mRNA水平;ELISA法检测其上清液中IL-6、CRP和血清淀粉样蛋白A(SAA)蛋白水平,免疫比浊法检测其上清液中C3蛋白水平。结果:培养的A549细胞在不同浓度和不同时间的E.coli诱导下,表达IL-6、C3和CRP mRNA及IL-6、C3、CRP和SAA蛋白水平呈浓度和时间的依赖性。与对照组相比,均有显著性差异(P<0.05)。结论:呼吸道上皮细胞在病原微生物刺激下,表达多种非特异性免疫效应分子,积极清除外来致病物,发挥重要的固有免疫防御作用。上皮细胞还可能在固有免疫和适应性免疫之间起连接作用。

Objective： The respiratory epithelium plays important roles. In this study the mechanisms of innate immune response in respiratory epithelium and the capacity of stress reaction for E. coli were investigated. Methods ： Human pulmonary epithelial-derived cell line A549 was normally cultured and heat-inactivated E. coli in different concentration or times was added 24 h after cell line was transferred. The expression of IL-6, C3 and CRP at the mRNA levels in the cells were measured by semi-quantitative reverse transcriptase polymerase chain reaction （RT-PCR） analysis. The expression of IL-6, CRP, SAA and C3 at the protein level in the supernatant was measured by enzyme-linked immunosorbent assay and immunonephelometry. Results ： Heat-inactivated E. coli at different concentrations and for different time induced the expression of IL-6, C3 and CRP mRNA and the secretion of IL-6, C3, CRP and SAA in A549 cells with a concentration-and time-dependent increase. The difference between each experimental group and control group was significant （P 〈 0.05 ）. Conclusion： The respiratory epithelium produces a lot of nonspecific immunological melmules in host responses to infectious stimuli. These molecules eliminate microorganisms positively and play imp,,rtant roles in host responses to infection. The epithelium may act as a bridge between inflate and adaptive immunity at the mucosal surface of the airways.