Effects Of Epigallocatechin Gallate On Bleomycin Induced Pulmonary Fibrosis In Rats And Its Mechanisms

Objective: To study the effects of epigallocatechin gallate(EGCG)on bleomycin induced pulmonary fibrosis in rats and its mechanisms.Methods: 126 Sprague-Dawley male rats were randomly divided into six groups:Control group, BLM model group,Prednisolone group(3.36 mg.kg -1.d -1)and three EGCG groups(100 mg.kg -1.d -1,50 mg.kg -1.d -1,25 mg.kg -1.d -1). All the animals except those in normal control group were given bleomycin endotracheally. Then each group gave corresponding drugs orally. On days 7,14, 28 after drugs administration, the animals in each group were randomly killed and the lung tissues were harvested for histopathological studies,electron microscope analyses and immunohistochemical determination of TGF-β1, Smad2/3 and Smad7.Furthermore, the contents of T-AOC,SOD,MDA,MPO and HYP were determined in lung tissues.Results: (1) EGCG could decrease the pulmonary index compared with that of model group(P<0.01,P<0.05); (2) EGCG could obviously reduce inflammatory cells exudation and collagen deposition in lung tissues of pulmonary fibrosis model(P<0.01,P<0.05); (3) EGCG could decrease the expression of TGF-β1 and Smad2/3, and increase the expression of Smad7(P<0.01,P<0.05); (4)EGCG could enhance the activity of SOD, and raise the level of T-AOC in lung tissues(P<0.01,P<0.05), and reduce the contents of MDA,MPO (P<0.01,P<0.05). (5)EGCG could significantly lessen amount of HYP compared with that of model group in lung tissues(P<0.01,P<0.05).Conclusion: EGCG can decrease the pulmonary index compared with that of model group. The degree of alveolitis and pulmonary fibrosis in EGCG groups significantly decreases compared with model group. The therapeutic and preventive effect of EGCG in treating pulmonary fibrosis is associated with inhibiting action on oxygen free radicals, reducing the expression of TGF-β1,Smad2/3 and improving the expression of Smad7 thereby decreases the abnormal collagen deposition and lessenes pulmonary pathological damage in lung tissues of rats.