蛋白酶激活受体1介导人肺上皮细胞分泌白细胞介素-8

目的探讨蛋白酶激活受体1（PAR1）激动肽和凝血酶对人肺上皮细胞白细胞介索-8（IL-8）分泌的影响。方法人肺上皮细胞系A549细胞分别接种于12孔培养板各孔内，并分别用不同浓度的PAR1激动肽SFLLR和反PAR1激动肽RLLFS以及不同浓度的凝血酶和／或凝血酶抑制剂水蛭索进行刺激，刺激时间为2和16h。用ELISA方法检测上清液中的IL-8水平。结果经过16h的培养，SFLLR可引起浓度相关性IL-8的释放增加，增加到300μmol/L时诱导IL-8的释放量比基础分泌量增加了近16倍，RLLFS不能引起IL-8的释放增加。凝血酶也可引起浓度相关性IL-8释放．凝血酶在浓度1kU／L时就可引起IL-8释放量增加，10kU/L时诱导IL-8释放量达高峰，为基础分泌量的7．5倍。水蛭索可以抑制凝血酶对IL-8的释放作用。时间相关曲线表明，PAR1介导的IL-8释放从2h起即可引起增加，16h达高峰。结论PAR1激动肽和凝血酶可促进人肺上皮细胞分泌IL-8，PAR1拮抗剂和凝血酶抑制剂可能具有抗炎作用。

Huinan lung epithelial cells produce interleukin-8 through protease-activated receptor 1

OBJECTIVE: To investigate the actions of protease-activated receptor 1 (PAR1) agonists and thrombin on the secretion of interleukin-8 (IL-8) from human lung epithelial cells. METHODS: A549 cells were cultured in a 12-well culture plate. The challenge was performed by addition of various concentrations of PAR1 agonist peptides SFLLR and its reverse peptides RLLFS, thrombin or hirudin, a thrombin inhibitor, into each well, respectively. After 2 or 16 h, the reactions were terminated by removal of the supernatant from each well. A sandwich enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of IL-8 in the supernatants. RESULTS: Following a 16-hour incubation, SFLLR was able to induce concentration-dependent secretion of IL-8. The maximum release of IL-8 was increased nearly 16 fold more than the baseline release. The reverse PAR1 agonists had little effects on IL-8 release. Thrombin was also able to induce concentration- dependent secretion of IL-8. As low as 1 kU/L thrombin was able to induce IL-8 release from the epithelial cells, and the maximum accumulated release of IL-8 was observed with 10 kU/L thrombin, which was 7.5 fold the baseline release. Thrombin inhibitor hirudin could inhibit thrombin-induced secretion of IL-8. The time course showed that the actions of PAR1 agonist peptides SFLLR and thrombin initiated at 2 h and reached the peak at 16 h. CONCLUSION: PAR1 agonist peptides and thrombin are potent secretogogues of IL-8 release from cultured human lung epithelial cells, and PAR1 antagonists and thrombin inhibitor may possess the ability to inhibit airway inflammation.