The Study On The Expression Of Interleukin-17-Producing CD4+T Helper Lymphocytes In Lungs Of Mice After Smoking Cessation

Objective To evaluate the expression of Th17cells in lungs of cigarette smoke-induced mice and smoking cessation mice,and to explore the relationship between Th17cells and lung inflammation or emphysema of smoking cessation mice.Methods There are Fifty male BALB/c mice, which were randomly divided into5groups, with10mice in every group, including a smoke-exposure12weeks group (S1), a smoke-exposure24weeks group (S2), a smoking cessation group (smoke-exposure12weeks and then with12weeks’smoking cessation)(S3), a control group12weeks (C1), a control group24weeks (C2). Morphological changes were evaluated by Lm (mean linear intercepts) and DI (destructive index). ELISA(Enzyme linked immunosorbent assay) was used to detect the levels of TNF-a and IL-6. The mRNA expression of IL-17and RORyt was measured by real-time PCR. The proportion of CD4+IL-17+T cell in lungs of mice was determined by flow cytometry.Results Mean linear intercepts in S1and S2groups [(39.19±3.51)μm and (46.87±7.16)μm]and DI in S1and S2groups[(39.13±1.57) and (45.16±3.13)] were significantly higher than those in C1and C2groups [(32.38±3.73)μm and (32.60±3.21)μm] and [(28.23±1.62) and (28.86±2.07)]. Compared with S2group, the Lm and DI in S3group [(43.16±1.73)μm] and [(43.01±2.04)] showed a lower value, but still higher than those in S1group, all P<0.05. The levels of TNF-a in S1and S2groups [(77.24±13.68) ng/L and (101.71±18.98)ng/L] and IL-6in S1and S2groups [(558.5±68.6) ng/L and (669.1±99.7) ng/L] were higher than those in C1and C2groups[(62.10±16.11) ng/L and (64.37±15.12) ng/L]and[(492.5±28.1) ng/L and (484.0±28.1) ng/L]. Compared with S2group, the levels of TNF-a and IL-6in lungs of S3group[(87.36±8.37) ng/L] and[(612.4±22.0) ng/L] showed a lower value, but still higher than those in S1group, all P<0.05.In lungs, the mRNA expression of RORyt and IL-17in S1and S2groups [(25.50±3.75) and (43.10±5.76)] and [(25.50±3.03) and (43.40±5.38)] were higher than those in C1and C2groups [(10.00±4.83) and (11.20±7.35)] and [(12.70±5.12) and (8.30±6.07)]. Compared with S2group, the mRNA expression of RORyt and IL-17in S3group [(37.70±5.36)] and [(37.60±5.13)] showed a lower value, but still higher than those in S1group, all P<0.05. In lungs, the percentage of Th17in S1and S2groups [(3.27±1.12)%和(7.19±2.24)%] were significantly increased than that in C1and C2groups [(1.80±0.75)%和(1.99±0.59)%]. Compared with S2group, the percentage of Th17in S3group [(4.57±1.15)%] showed a lower value, but still higher than that in S1group, all P<0.05. In lungs, the frequency of Th7cells, the mRNA expression of RORyt and IL-17in S1,S2and S3groups all had positive correlations with Lm and DI (r=0.709and0.674,0.802and0.812,0.705and0.766, all P<0.05).Conclusions Lung interleukin-17-producing CD4+T helper lymphocytes remains increasing on Cigarette Smoke-induced mice despite12weeks’ smoking cessation, suggesting that the up-regulation of Th17cells may be involved in the emphysema, and inflammation persistenting after smoking cessation.