Pathology of bleomycin induced acute lung injury and early initiation of the pulmonary fibrosis in mice

Intratracheal instillation of bleomycin is the standard and most common route of administration in animal models as this induces the rapid development of pulmonary fibrosis. In this study, we investigated the incidence/occurrence of pulmonary fibrosis in the time course of one week in mice model on single intratrachial instillation of bleomycin. Adult albino mice were divided into two groups namely, control group (saline alone) and treatment group (bleomycin @ 1mg/kg intratracheally once). On day 7, mice of both groups were sacrificed; BALF and lungs were collected. Lung injury was assessed by protein concentration in BALF, biochemical parameters like cytokines (TNF-α, IL-6 and TGF-β1) estimation, MPO activity, NF-kB activity, oxidative stress markers (LPO, NO), hydroxyproline assay, histopathology, immunohistochemistry (E-cadherin, vimentin and alpha -smooth muscle actin) and ultra-structural examination of lung tissue. The present study showed an increase in hydroxyproline content and TGF-β1 levels in lung homogenates as well as expression of mesenchymal marker mainly vimentin on IHC indicating pulmonary fibrosis in acute phase of bleomycin challenged mice.