[Human 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.


CONCLUSIONS
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.
Wang
Hai-yan
HY
Allergy and Inflammation Research Institute, Medical College of Shantou University, Shantou 515031, China. hywang@stu.edu.cn
He
Shao-heng
SH
Zheng
Yan-shan
YS
D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology; D009842:Oligopeptides / Q000494:pharmacology; D044463:Receptor, PAR-1 / Q000819:agonists*; D013917:Thrombin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
C090291:C186 65; D016209:Interleukin-8; D009842:Oligopeptides; D044463:Receptor, PAR-1; D013917:Thrombin