Expressions of IL-17, IL-21, RORγt in lung tissue of COPD rats and the effect of simvastatin on it

Abstract

Objective To observe the effects of simvastatin on smoking induced COPD in the lung tissues of rats with IL-17, IL-21 and retinoid-related orphan nuclear receptor gamma t(ROR γ t) expression, to explore the value of simvastatin in the treatment of COPD and its mechanism. Methods Male SD rats were randomly divided into three groups: control group (n=10), smoking group (n=11) and treatment group (n=10). The pathological changes of lung tissue were observed in each group.The distribution of IL-17, IL-21 and RORγt protein in lung tissue of rats were detected by immunohistochemical method.The mRNA expression of IL-17, IL-21 and RORγt in rat lung tissue was measured by real-time RT-PCR. Results In the bronchial epithelium and alveolar septa, the expression of IL-17, IL-21 and RORγt positive cells were higher in smoking group [(90.00±14.02) cells/mm2, (61.18±9.16) cells/mm2, (77.27±7.95) cells/mm2]and treatment group [(72.80±10.79) cells/mm2, (49.40±3.34) cells/mm2, (65.40±5.23) cells/mm2]compared with control group[(5.20±4.49) cells/mm2, (8.20±3.16) cells/mm2, (6.80±5.85) cells/mm2](P<0.01), and the expression of smoking group was higher than the treatment group (P<0.05). The mRNA expression of IL-17, IL-21 and RORγt in lung tissue of smoking group (7.49±2.93, 12.22±4.98, 4.04±0.21) and treatment group (2.39±0.62, 3.78±0.35, 1.76±0.25) were higher than those in control group (1.00±0.00, 1.00±0.00, 1.00±0.00) (P<0.01), and the expression level in smoking group was higher than that in control group (P<0.05). There was a positive correlation between the number of IL-17 positive cells in the alveolar septum and the mean linear intercept (r=0.729, P<0.01), which was negatively correlated with the mean alveolar number (r=-0.889, P<0.01). Conclusions IL-17, IL-21 and RORγt plays a role in the process of COPD formation in rats, simvastatin reduced expression of inflammatory cells and inflammatory factors IL-17, IL-21 and RORγt, this effect is one of the mechanisms of simvastatin to reduce inflammatory reaction and the change of lung pathology in lung tissue of COPD rats. Key words: Chronic obstructive pulmonary disease; Interleukin-17; Interleukin-21; Retinoid-related orphan nuclear receptor gamma t; Simvastatin