[Protective effect of anti-idiopathic pulmonary fibrosis drug Pirfenidone and Sufenidone (SC1011) on pulmonary injury induced by tuberculosis in a mouse tuberculosis model]

Objective: To evaluate the protective effect of anti-idiopathic pulmonary fibrosis (IPF) marketed drug Pirfenidone and its clinical drug Sufenidone (SC1011) against lung injury in a mouse tuberculosis model. Methods: C57BL/6 mouse model of tuberculosis was established. A total of 75 C57BL/6 mice were infected with 1×10⁷ CFU/ml H37Rv suspension by aerosol and randomly divided into untreated (n=9) group, isoniazid+rifampicin+pyrazinamide (HRZ) group (n=22), PFD+HRZ group (n=22), and SC1011+HRZ group (n=22). C57BL/6 mice were infected with H37Rv by aerosol for 6 weeks and then treated. Seven mice in each treatment group were weighed, sacrificed, dissected and observed for lung and spleen lesions at 4 and 8 weeks of treatment. HE staining and Masson staining were used to assess degree of lung injury and fibrosis, respectively. ELISA was used to assess the IFN-γ/TNF-α content in the serum of mice in each treatment group after 4 weeks of treatment. Hydroxyproline (HYP) content in lung tissue was measured by alkaline hydrolysis; meanwhile, CFU counts were used to assess the bacterial load in the lung and spleen of mice in each treatment group and the recurrence of spleen and lung tissue after 12 weeks of drug withdrawal. Results: At 8 weeks, the HYP content in the lung tissue was (630±58), (635±17), and (840±70) μg/mg in the PFD+HRZ, SC1011+HRZ, and HRZ treatment group, respectively (P<0.05).At 8 weeks, the proportion of Masson staining blue-stained area, that was, positive area, in lung tissue was 16.65%±1.82%, 10.01%±2.16%, and 21.36%±3.21%, respectively (F=27.11, P<0.001).The lung injury scores by HE staining at 8 weeks were (5.00±0.50), (5.00±0.47), and (6.89±0.99) points, respectively (F=19.81, P<0.001).The results of 4-week ELISA showed that the levels of TNF-α and IFN-γ in the serum of the SC1011+HRZ-treated group were lower than those of the HRZ-treated group (all P<0.05).The degree of lung injury and fibrosis in PFD+HRZ and SC1011+HRZ treatment groups were lower than those in HRZ treatment group (all P<0.001). The number of viable bacteria in the lung tissue of mice treated with PFD+HRZ, SC1011+HRZ, and HRZ for 4 weeks was lower than that of mice untreated [(1.82±0.10), (1.91±0.05), (1.79±0.17) vs. (5.27±0.07) lg(CFU+1)/ml, all P<0.05)]. And the aseptic transformation of the spleen of mice was achieved in each treatment group at 8 weeks of administration. After 12 weeks of drug withdrawal, the recurrence of lung infection in the SC1011+HRZ treatment group was 3/7 lower than 5/7 in the HRZ treatment group (P>0.05); the recurrence of spleen infection in the SC1011+HRZ treatment group was 1/7 lower than 5/7 in the HRZ treatment group (P>0.05).Pulmonary infection recurred more frequently in PFD+HRZ 6/7 versus HRZ 5/7 (P>0.05). Conclusions: PFD/SC1011, when combined with HRZ, reduced lung injury and reduced secondary fibrosis in pulmonary tuberculosis in C57BL/6 mice. SC1011 combined with HRZ has no significant short-term therapeutic effect on MTB, but may reduce its recurrence rate in long-term treatment, especially in reducing the recurrence rate of mouse spleen.