The role of interleukin-17 in pathogenesis of acute lung injury

Objective:To investgate the role of interleukin-17(IL-17) in pathogenetic mechanism of acute lung injury(ALI) by oleic acid(OA).Method:A rat model of ALI was established by intravenous injection of oleic acid with a dose of 0.1 mL/kg. RT-PCR and IHC methods were used to determine the expression level of IL-17 mRNA and protein in lung tissue, respectively. The concentrations of IL-17 in bronchoalveolar lavage fluid(BALF) and the lung homogenates were determined by ELISA. The number of leukocytes in BALF was counted. Pressure of oxygen in arterial blood was determined. The concentration of total protein in BALF was examined, and pathologic changes of lung tissue were measured using a semi-quantitative scoring system.Result:IL-17 was expressed at lower level in lungs and BALF of normal rats, mainly by epithelial cells. At 1st, 2nd and 4th hour after OA infusion, the expression of IL-17 was not changed. At 6th hour, it was significantly upregulated and there were more IL-17-positive mononuclear cells in the interstitial, which was significantly different from other groups( P 0.05). In the normal group and 6 h group, the level of IL-17 protein expression in BALF was positively correlated with the percent of neutrophils in BALF( r =0.682, P 0.05). Conclusion:In OA-induced (0.1 mL/kg) ALI in rats, the upregulation of expression of IL-17 in lung appears later than the presentation of neutrophil infiltration and hypoxemia. IL-17 may be involved in the pathogeneis in later phase.