Effect of cigarette smoke exposure on the interleukin-17-producing CD4+T helper lymphocyte in mice with emphysema
Objective To investigate the effect of cigarette smoke exposure on the interleukin-17-producing CD4+T helper lymphocyte( Th17 ) in peripheral blood and lungs of cigarette smoke-induced emphysema mice. Methods Forty male BALB/c mice were randomly divided into 4 groups, including a control group C12, a control group C24, a smoke-exposure group S12 and a smoke-exposure group S24, 10 mice each group. Morphological changes were evaluated by mean linear intercepts (Lm) and destructive index (DI). The concentration of IL-17, IFN-γ and TNF-α in bronchoalveolar lavage fluid(BALF) and the concentration of IFN-γ and TNF-α in lung homogenates were measured by enzyme-linked immunosorbent assay (ELISA). The proportion of CD4+IL-17+ Th17 cells in peripheral blood and lungs of mice was determined by flow cytometry. The mRNA expressions of RORγt and IL-17 in peripheral blood and lungs were evaluated by real-time PCR. Results Lm and DI were significantly higher in S12 and S24 groups [(39.19±3.51)μm vs (46.87±7.16) μm, 39.13±1.57 vs 45.16±3.13]than that in C12 and C24 groups [(32.60± 3.21 ) μm vs (32.38±3.73) μm, 28.23± 1.62 vs 28.86±2.07], all P＜0.05. IL-17, IFN-γand TNF-α in BALF of S12 and S24 groups [(119.72±10.72) ng/L vs (296.40±14.00) ng/L,(129.7±22.2) ng/L vs(251. 1±62.4) ng/L, (17.35±1.60) ng/L, (36.35±1.43) ng/L]were higher than those in C12 and C24 groups [(52.06±4.70) ng/L vs (51.89 ±6.82) ng/L, ( 85.8 ±26.8) ng/L vs ( 88.9 ± 11.5 ) ng/L,(6.41 ±0.90) ng/L vs (5.85±0.92) ng/L], IFN-γ and TNF-α in lungs of S12 and S24 groups [( 1124.3±174.4) ng/L vs (1342.7±206.1) ng/L, (77.2±13.7) ng/L vs (101.7±19.0) ng/L, (129.7±22.2)ng/L vs (251.1 ±62.4) ng/L]were higher than those in C12 and C24 groups[(946.2±81.9) ng/L vs (1027.2±188.3) ng/L, (62.1±16.1) ng/L vs(64.4±15. 1) ng/L], all P＜0.05. The percentage of Th17 cells in lungs of S12 and S24 groups [(3.27±1.12)％ vs (7.19±2.24)％, ( 1.96±0.61 )％ vs (3.82±1.26)％]was significantly increased as compared with that of C12 and C24 groups [(1.80± 0.75)％ vs (1.99±0.59)％], all P＜0.05. And the percentage of Th17 cells in peripheral blood of S12 and S24 groups [(1.96±0.61)％ vs ( 3.82± 1.26)％]was also significantly higher than those in C12 and C24 groups [(0.90±0.37)％ vs (0.97±0.32)％], all P＜0.05. In peripheral blood and lungs,the mRNA levels of RORγt and IL-17 in S12 and S24 groups were higher than in C12 and C24 groups, all P＜0.05.Moreover, the frequency of Th17 cells in peripheral blood and lungs had a positive correlation with Lm and DI( r=0.706-0.772 ,all P＜0.05 ). Conclusion An up-regulation of proportions Th17 in peripheral blood and lungs of cigarette smoke-inducsed emphysema mice were detected. It may be involved in the amplified and persistent inflammation. 
 
Key words: 
T helper 17;  Inflammation;  Cigarette smoke exposure;  Emphysema