The Role Of CD4+Foxp3+Regulatory T Cell In Smoking-Exposure And Smoking Cessation Rats

Objective:To evaluate the expression of Treg in a cigarette smoke-induced rat model of emphysema and smoking cessation rats, and to explore the role of Treg in cigarette smoke-induced inflammation and emphysema of rat.Methods:Fifty male Wistar rats were randomly divided into 12 Weeks control group(group C1),24 weeks control group(group C2),12 weeks smoke-exposure group(group S1),24 weeks smoke-exposure group(group S2) and smoking cessation group(group S3),10 rats each group. Alveolar airspace enlargement was observed by hematoxylin-eosin(HE) staining. IL-8 and TNF-a levels in BALF were tested by ELISA. The proportion of CD4+Foxp3+ Treg in peripheral blood and lungs of rats was determined by Flow Cytometry. The mRNA expression of Foxp3 was measured by Real-Time PCR.Results:(1) The mean linear intercept (MLI) in group S1 and group S2 [(64.88±5.31)μm, (77.89±11.53)μm] were higher than those in group C1 and group C2[(38.95±3.76)μm, (40.30±2.67)μm],(P<0.01).Compared with group S2,the MLI in smoking cessation group (71.46±5.84)μm have a lower value (P<0.01),but still higher than in group S1 (P<0.01). (2) The IL-8 and TNF-a levels in BALF of goup S1 and group S2 [(67.58±16.97) pg/ml, (84.61±16.37) pg/ml], [(14.14±1.80) pg/ml, (20.13±8.67) pg/ml] were higher than those in group C1 and group C2 [(44.48±8.47) pg/ml, (43.17±8.84) pg/ml], [(6.32±2.26) pg/ml, (5.80±1.57) pg/ml], (P<0.05). The IL-8 and TNF-a levels were not statistically different between in smoking cessation group (55.72±5.65) pg/ml, (14.66±4.70) pg/ml and group S1. (3) The percentage of CD4+Foxp3+Treg in the lungs of group S1 and group S2[(6.62±0.75)%, (5.28±0.91)%] was significantly decreased as compared to group C2 and group C2 [(9.04±0.95)%, (9.58±0.87)%], (P<0.01). The percentage of CD4+Foxp3+Treg in lungs was not statistically different between group S1 and smoking cessation group (7.15±0.61)%. In peripheral blood, there was not significantly different between groups for the percentage of CD4+Foxp3+Treg. (4) In lung, the Foxp3 mRNA expression in group S1 and group S2 [(16.5±7.0), (9.1±7.3)] was less than in group C1 and group C2[(38.7±5.5), (41.9±6.9)], (P<0.01). The Foxp3 mRNA expression was not statistically different between group S1 and smoking cessation group (21.4±8.6). No significant differeces in peripheral blood Foxp3 mRNA expression were found between groups.Conclusions:Dcreased Treg in lungs of cigarette smoke exposure rats despite 12 weeks smoking cessation, suggests down-regulation of Treg may involved in the amplified inflammation and persists after smoking cessation in cigarette smoke-induced emphysema of rat.