The expression of Smad7 in the rats with pulmonary interstitial fibrosis and the therapeutic effect of IL-7

Objective To explore the expressions of Smad7 and TGF-β_1 in rats with pulmonary interstitial fibrosis and observe the effect of IL-7 on pulmonary fibrosis.Methods Forty eight Wistar rats were assigned into 3 groups:saline parallel group(N group,n=12),fibrosis group(F group,n=18)was established through intratracheal instillation of bleomycin and IL-7 treated group(Ⅰgroup,n=18)was established by injecting of IL-7 introceliacally 5 times per week for 2 weeks.Hydroxy proline(HYP)and hyaloplasmic acid in the lung and the histopathologic changes of lung were evaluated on days 7,14,28 respectively.The expressions of TGF-β1 and Smad7 were detcted by immunochemistry method.Results①HYP was decrease inⅠgroup[(2.06±0.23)ng/ml]than that in F group[(2.99±0.27)ng/ml]at the same time(P＜0.01).②The degree of alveolitis and pulmonary fibrosis was alleviated inⅠgroup compared to F group at the same time(P all＜0.01).③The expression of TGF-β_1 was higher in F group(3.97±0.20)than that in N group(0.74±0.18)at the same time(P all＜0.01).④The activity of Smad7 was increased inⅠgroup(2.45±0.37)vs N group(1.78±0.29)at the same time(P all＜0.01).Conclusions TGF-β1 plays an important role in the pathogenesis of pulmonary fibrosis.Smad7 is deficient in pulmonary fibrosis and plays a counter-regulatory role with TGF-β_1 in fibroblast collagen synthesis.IL-7 may alleviate the process of rat pulmonary fibrosis induced by bleomycin through stimulating the erpression of Smad7.