| Research backgroundPathophysiologic features of asthma are chronic inflammation,hyperreactivity and repeated damage and repairing of airway epithelium. There is a significant rise in asthma incidence in recent decades although glucocorticosteriods are widely used in treatment,but problems follow as glucocorticoid-resistance and drug side-effects. So many researches showed that the imbalance of Th1/Th2 may be an important Immunologic change in asthma…, while Th2 cytokine IL-13 take great part in the progress of asthma. Some researches have showed that IL-13 possibly Played an important role in asthma through asthma through multiple mechanisms. Whether IL-13 promotes airway epithelium apoptosis or not is Still unknownEgr-1 is One of members of Instant Early Gene families which can induce several nearby gene transcription so as to suppress cell growth through Apoptosis of Induction Factor. Egr-1 also Plays a role in the cell cycle G0-G1 time and regulates cell growth and differentiation, so that cells don,t overgrow. Bc1-2 gene family is very important in cell signal transduction pathway of cell apoptosis, in which Bc1-2 and Bax are the most typical genes suppressing or accelerating airway epithelium apoptosis. Bax/Bcl-2 ratio decides if airway epithelium apoptosis or not. Some researches have shown that IL-13 could cause DNA damage and cell death of rat typeⅡpneumonocytes through Egr-1 pathway and increase mRNA level of genes coding Bax . But if IL-13 could cause airway epithelium apoptosis through Egr-1 pathway , decrease Bcl-2 and increase Bax expression or not are unknown.Objectives: To explore effects of IL-13 on mRNA and protein expression of Egr-1, Bax and Bcl-2 in 9HTE airway epithelium, and to explore mechanisms of IL-13 in promoting airway epithelium apoptosis which may provide theoretical basis for regulating imbalance immune function of asthma with cytokine antagonist in future prevention and treatment of asthma.Method: 9HTE airway epithelium were divided into 3 groups: control group, rhIL-13 group, and rhIL-13 +mAIL-13 group, each group contained 8 duplicate wells.(1) mRNA measurement of each hole with RT-PCR.(2) Protein measurement of each well with ICC.Result: (1)Results of RT-PCR: The mRNA level of Egr-1 in IL-13 group was significantly higher than that in control group(1.03±0.13 vs 0.54±0.08,P<0.01),the mRNA level of Egr-1 in rhIL-13 +mAIL-13 group as significantly lower than that in IL-13 group(0.71±0.25 vs 1.03±0.13,P<0.0w1), but there was no significant difference between rhIL-13+mA- IL-13 group and control group(0.71±0.25 vs 0.54±0.08,P>0.05). The mRNA level of Bax in IL-13 group was significantly higher than that in control group((0.58±0.01 vs0.37±0.08,P<0.01), the mRNA level of Bax in rhIL-13 +mAIL-13 group was significantly lower than that in IL-13 group(0.44±0.12 vs 0.58±0.01,P<0.01), but there was no significant difference between rhIL-13+mAIL-13 group and control group(0.44±0.12 vs 0.37±0.08,P>0.05). The mRNA level of Bcl-2 in IL-13 group was significantly lower than that in control group(0.48±0.06 vs 0.82±0.19,P<0.01, the mRNA level of Bcl-2 in rhIL-13+mAIL-13 group was significantly higher than that in IL-13 group(0.77±0.13 vs 0.48±0.06, P<0.01), but there was no significant difference between rhIL-13+mA IL-13 group and control group(0.77±0.13 vs 0.82±0.19,P>0.05).(2)Results of ICC: The protein level of Egr-1 in IL-13 group was significantly higher than that in control group(0.0975±0.0276 vs 0.0505±0.0113,P<0.01),the mRNA level of Egr-1 in rhIL-13 +mAIL-13 group was significantly lower than that in IL-13 group(0.0556±0.0118 vs0.0505±0.0113,P<0.01), but there was no significant difference between rhIL-13+mAIL-13 group and control group (0.0556±0.0118 vs 0.0975±0.0276,P>0.05). The protein level of Bax in IL-13 group was significantly higher than that in control group((0.58±0.01 vs 0.37±0.08,P<0.01),whereas the protein level of Bax in rhIL-13 +mAIL-13 group was significantly lower than that in IL-13 group(0.0060±0.0015 vs 0.0548±0.0128,P<0.01); but there was no significant difference between rhIL-13+mA IL-13 group and control group(0.0056±0.0014 vs 0.0060±0.0015,P>0.05). The protein level of Bcl-2 in IL-13 group was significantly lower than that in control group(0.0309±0.0114 vs 0.0592±0.0112,P<0.01), the protein level of Bcl-2 in rhIL-13+mAIL-13 group was significantly higher than that in IL-13 group(0.0584±0.0102 vs0.0309±0.0114,P<0.01), but there was no significant difference between rhIL-13+mAIL-13 group and control group (0.0584±0.0102 vs0.0592±0.0112,P>0.05).Conclusion: (1)IL-13 can up-regulate mRNA and protein expression of Egr-1 and Bax, down-regulate mRNA and protein expression of Bcl-2 in 9HTE airway epithelium, which suggest that IL-13 possibly promote 9HTE airway epithelium apoptosis through Egr-1 pathway.(2) mAIL-13 can decrease Egr-1 and Bax through neutralizing their mRNA and protein expression, and increase Bcl-2 through neutralizing their mRNA and protein expression in 9HTE airway epithelium, Which suggests that mAIL-13 may neutralize effect of IL-13 in promoting apoptosis promoting apoptosis of 9HTE airway epithelium. Our results provide new possibility as a new drug for prevention and cure of asthma. Therefore identification of effect of IL-13 in asthma can provide us theoretical and experimental basis for future effective prevention and treatment of asthma with IL-13 antagonist and neutralizing antibody.
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