Abstract: To evaluate the effects and mechanism of Huayulifei on blemycininduced pulmonary interstitial fibrosis in rats. MethodsRats were randomly divided into the control group, the model group, the Huayulifei group and the hydrocortisone group. Rat pulmonary fibrosis was induced by blemycin(5?mg/kg) in the experimental groups and 0.9% saline in the control group. Rats were killed on the 7th，14th and 28th days. Expressions of MMP2 and TIMP1 proteins were determined by an immunohistochemical technique. Results① The airsacculitis and fibrosis of lungs in the model group were fairly severe which had much deposition of collagen fibers. In the Huayulifei group which had few inflammatory cells, the alveoli structure was nearly normal, and most of the airsacculitis and fibrosis of lungs were mild. In the Hydrocortisone group, alleviation of airsacculitis and fibrosis of lungs were similar with those of the Huayulifei group. ② In the Huayulifei group, expressions of MMP2 protein and TIMP1 protein were significantly lighter than those in the model group. ConclusionHuayulifei can ameliorate blemycininduced pulmonary fibrosis in rats, and it may partly work by affecting the expression of MMP2/TIMP1.

Key words: Pulmonary fibrosis, Huayulifei, Matrix metallopeptidase2, Tissue inhibitor of metalloproteinase1, Rats,Wistar