Inhibition of experimental acute pulmonary inflammation by pirfenidone

Pirfenidone, a putative tumor necrosis factor-alpha (TNF-alpha) inhibitor, has recently gained recognition for its therapeutic use in the treatment of idiopathic pulmonary fibrosis. As pulmonary fibrosis may be the result of lung inflammatory processes, we examined the anti-inflammatory potential of pirfenidone in several models of acute pulmonary inflammation. In antigen-induced allergic paradigms, 24 h after antigen challenge, sensitized mice or guinea pigs develop a prominent pulmonary inflammation, reflected by a significant increase in the number of recoverable bronchoalveolar lavage (BAL) total cells and eosinophils. In both species, the pretreatment of animals with pirfenidone (10 and 30 mg/kg) resulted in a dose-dependent inhibition of the antigen-induced pulmonary inflammation, which was reflected by a significant decrease in the BAL eosinophils and total cells by the 30 mg/kg dose. In a non-allergic model of pulmonary inflammation, rats challenged with intratracheal LPS develop a significant increase in BAL neutrophils and total cells, along with significant increases in TNF-alpha and IL-6. Pretreatment with pirfenidone (3 and 30 mg/kg) showed a dose-dependent inhibition of the LPS-induced pulmonary inflammation, reflected by a significant decrease in the number of BAL total and neutrophilic cells at both the 3 and 30 mg/kg dose. However, pirfenidone had no effect on the peak BAL levels of TNF-alpha. In contrast, pirfenidone significantly inhibited BAL levels of IL-6. In summary, we have shown that pirfenidone can inhibit allergic and non-allergic inflammatory cell recruitment and that its pulmonary anti-inflammatory activity is independent of TNF-alpha inhibition.