Abstract: Objective To observe the effects of Tianlongjie (a Yunnan ethnic medicine) stage interventions on lung tissue remodeling and lung function of pulmonary fibrosis (PF) rats and explore the possible mechanism of Tianlongjie against pulmonary fibrosis. Methods A pulmonary fibrosis model of rats was established via intratracheal bleomycin infusion. Ninety male Wistar rats were randomized into nine groups: the control group(C), model early group(ME) and model late group(ML), Tianlongjie early intervention group at a medium dose(TEM), Tianlongjie late intervention group at a low dose(TLL), Tianlongjie late intervention group at a medium dose(TLM) , Tianlongjie late intervention group at a high dose(TLH)（0.51,1.01,2.02 g·kg^-1·d^-1）, pirfenidone early intervention group(PFDE) and pirfenidone late intervention group(PFDL). Rats in the early intervention group was given drugs from the 7^th day after modeling while the late intervention group was given drugs from the 14^th day. The survival of rats was observed and materials were selected on the 28^th day. The protein expressions of CD31 and CD34 in lung tissue were detected by SABC. The content of Hyp in lung tissue was determined with colorimetry. The lungs were stripped before the lung coefficient was calculated. Pulmonary function was measured by an animal pulmonary function instrument. Blood samples were taken from the abdominal aorta for blood gas analysis. Results Compared with the model control group, CD31 and CD34 protein expressions in lung tissue of PF rats were inhibited in early and late intervention with Tianlongjie groups (P<0.01, P<0.001), and there was significant difference between TEM and TLM (P<0.05). Compared with TLL, TLM and TLH were more effective (P<0.05). Early and late intervention with pirfenidone inhibited CD31 and CD34 protein expressions in lung tissue of PF rats (P<0.01). There was no statistically significant difference between TEM and PFDE(P>0.05), and the same was true of TLM and PFDL. Compared with the model control group, the level of Hyp in lung tissue of PF rats decreased in each of the intervention groups (P<0.05,P<0.01). There was no statistically significant difference between TEM and PFDE(P>0.05), as in the case of TLM and PFDL. Compared with the model control group, intervention with Tianlongjie reduced lung weight and lung coefficients (P<0.05, P<0.01). There was no significant difference between Tianlongjie intervention and pirfenidone intervention (P>0.05). Compared with the model control group, intervention with Tianlongjie increased levels of FVC, FEV200 and FEV200/FVC (P<0.05, P<0.01, P<0.001), but decreased FRC levels(P<0.001). Conclusion Early and late intervention with Tianlongjie can effectively inhibit CD31 and CD34 protein expressions, and early intervention is more effective. Intervention with Tianlongjie can decrease Hyp contents in lung tissue of PF rats before reducing the lung coefficient, improve lung ventilation function, but there is no significant difference between Tianlongjie and pirfenidone, indicating that Tianlongjie could effectively regulate lung tissue remodeling of PF rats and inhibit the progress of pulmonary fibrosis.

Key words: Tianlongjie, pulmonary fibrosis, vascular remodeling, lung coefficient, lung function, bleomycin infusion, pirfenidone, rats