In the present study, bleomycin intratracheal administration induced severe PF, as shown by Mallory’s trichrome stained sections, the fibrosis score, the elevated lung parenchymal hydroxyproline content, and the increased immunohistochemical expression of α-SMA, with the recruitment of CD68 positive macrophages into the lung parenchyma. This evidence concerns the gene CD68 and fibrosis.