A total fibrinogen deficiency is compatible with the development of pulmonary fibrosis in mice

In addition to their well-known roles in hemostasis, fibrinogen (Fg) and fi brin (Fn) have been implicated in a number of other physiological and patho physiological events. One of these involves the fibroproliferative response after acute lung injury, which is the focus of the current study, Mice wit h a total Fg deficieny (FG(-/-)) were generated by breeding heterozygous (F G(+/-)) pairs, each of which contained an allele with a targeted deletion o f its Fg-gamma-chain gene. The resulting FG(-/-) animals did not possess de tectable plasma Fg. FG(-/-) mice were then used to assess the roles of Fg a nd Fn in a bleomycin-induced acute lung injury model. Intratracheal adminis tration of bleomycin in wild-type and FG(-/-) mice resulted in equivalent d eposition of interstitial collagen and fibrotic lesions at days 7 and 14 af ter administration. This indicates that Fg and/or Fn are not essential for the development of bleomycin-induced pulmonary fibrosis.