a role for mesothelial cells in the genesis of idiopathic pulmonary fibrosis idiopathic pulmonary fibrosis ipf is a chronic progressive and lethal process of unknown etiology the subpleural localization of fibrosis is a hallmark of early ipf but no link between the pleura and ipf has been established yet we developed an experimental model of pleural fibrosis induced by adenovirusmediated gene transfer of transforming growth factor tgfbeta1 to mesothelial cells and observed collagen accumulation within the pleura but also in the subpleural parenchyma this subpleural fibrosis was associated in vivo with a mesothelialtomyofibroblast transformation mesotheliofibroblastoid transformation a process similar to the epithelialmesenchymal transition this phenotypic modification was also observed in vitro in mesothelial cells treated with recombinant tgfbeta1 these results suggest that mesothelial cells may have a central role not only in pleural fibrosis but also in the onset and progression of ipf