Abstract: Objective To observe the effects of Tianlongjie on the expression of TGF-β₁ and histopathological changes in lung tissue of pulmonary fibrosis(PF) rats and to explore the possible mechanism of Tianlongjie in treating PF. Methods Rat pulmonary fibrosis models were prepared by intratracheal bleomycin infusion. Ninety male Wista rats were randomized divided into 9 groups: control group(C), model early group(ME) and model late group(ML), Tianlongjie early intervention group with middle dose(TEM), Tianlongjie late intervention group with low dose group(TLL), TIANLONGJIE late intervention group with middle dose group(TLM), Tianlongjie late intervention group with high dose group(TLH)(1.26、2.52、5.04 g·kg^-1·d^-1). Pirfenidone early intervention group(PFDE) and Pirfenidone late intervention group(PFDL). Rats of early intervention group were given drug from 7^th day after PF model was established, and late intervention group was given drug from 14^th day. Observe the survival state of rats and select materials on the 28^th day. The protein and mRNA expression of TGF-β₁ in lung tissue were detected by SABC and Real Time PCR. HE staining and Masson triple staining of lung tissue were used to analyze the pathological morphology. Results Expression of TGF-β₁, Compared with the model group, early and late intervention with Tianlongjie inhibit the expression of TGF-β₁ mRNA and protein in lung tissue of PF rats (P<0.05, P<0.01), and there was a significant difference between TEM and TLM (P<0.05). Compared with TLL, the TLM and TLH were more effective (P<0.05). Early and late intervention with Pirfenidone inhibit the expression of TGF-β₁ mRNA and protein in lung tissue of PF rats (P<0.05). There was no statistical difference between TEM and PFDE(P>0.05), and the same was true in TLM and PFDL. Pathological morphology: The pathological results showed that intervention with Tianlongjie and Pirfenidone reduce the degree of alveolitis, the deposition of collagen and interstitial cell proliferation in lung tissue. The effect of early intervention is more obvious. Based on pathomorphology quantitative analysis, there was no statistical difference between TEM and PFDE (P>0.05). Conclusion Tianlongjie can effectively reduce bleomycin-induced alveolitis and fibrosis, early intervention has more significance. The mechanism may related to the inhibition of the expression of TGF-β₁ in lung tissue, which is an important factor affects the occurrence and development of PF.

Key words: Tianlongjie, TGF-β₁, pulmonary fibrosis, alveolitis, rats, bleomycin, pirfenidone