ABSTRACT
Objective To investigate the mechanism of an antifibrotic drug, pirfenidone, in preventing radiation-induced pulmonary fibrosis. Methods Male BALB/C mice were randomized into 4 groups:control group (C), radiation alone group (R), pirfenidone alone group (P), and pirfenidone plus radiation group (P + R). Irradiation was administrated to the whole pulmonary with a single fraction of 12 Gy. The pirfenidone was given 0. 3 ml/kg/d from 3 days prior to irradiation to 12 weeks after.Bronchoalveolar lavage fluid (BALF) from right lung was collected for macrophages counting every monthmonthly until 6 months after irradiation, and left lungs were collected and fixed for. The pulmonary fibrosis was assessed by Masson trichrome staining. The plasma transforming growth factor β(TGF-β) was measured by ELISA. The lung hydroxyproline was evaluated by alkaline solution. Results Compared to group R, the counts of macrophages in BALF in group P + R were reduced by 76% and 62%, and hydroxyproline levels were reduced by 21% and 24% at the 4th and 5th months, respectively. The plasma TGF-β decreased from the 3rd month to 5th month. Pirfenidone markedly ameliorated the severity of lung fibrosis at the 4 - 6th month after radiation. Conclusions Pirfenidone can prevent radiation-induced pulmonary fibrosis, the mechanism of which may be the reduced of inflammation and collagen deposition by decreasing macrophages and hydroxyproline.