Increased inflammation and fibrosis in lung of WT and gp91phox-/- mice but not MMP12gp91phox double knockout mice. At 21d post-bleomycin treatment, mice were sacrificed and lungs were fixed overnight in 4% paraformaldehyde and embedded in paraffin. Sections of 8 m were dye-stained by A, Masson's Trichrome stain and C, Picro Sirius red and were immunostained with TGFb antibody and color developed by Diaminobenzidine (DAB). (B). Arrows indicate blue collagen deposits (A), TGFb positive stain (B) and red collagen staining (C). In A, pink-purple stains indicate cytoplasm, and blue the nuclei of inflammatory cells. Light blue stains are collagenous deposits. While wildtype and gp91phox-/- (designated as NOX-/-) show increased collagen deposits and inflammation around airways post-ovalbumin (all sections are those of post- ovalbumin lung), the MMP-12-gp91phox double knockout lung shows minimum collagen deposition as well as TGFb expression. While A and B were at 60 × magnification, C was at 10 × magnification. A inset shows another area of collagen deposition in bleomycin-treated wildtype; NOXB and DKOB were bleomycin-treated gp01 phox-/- and double knockout mice respectively. The photomicrographs were taken using an Olympus VX4L microscope and Nikon digital camera. All photomicrographs were at 60 × magnification. Abbreviations: WB, wildtype mice treated with bleomycin; NOXB, bleomycin-treated gp91phox null; DKOB, bleomycin-treated MMP12- gp91phox double knockout.