Inflammatory and fibrotic traits in dystrophic muscle of patients with DMD and mdx mice. (A) Fibrin(ogen) accumulates in muscles of patients with DMD and in aged mdx mice. Immunohistochemistry for fibrin(ogen) (brown) in muscle biopsies of (top) patients with DMD and healthy subjects and in (bottom) wild-type (WT) and mdx diaphragms. (B) Increased fibrosis, fibroblast number and TGFβ signaling in dystrophic muscles. Staining for collagen deposition (Sirius red) and immunohistochemistry for fibroblast-specific protein (FSP)-1 and P-Smad2 was performed on muscle biopsies taken from patients with DMD and healthy subjects. (C) Presence of alternatively activated macrophages in diaphragm muscle of mdx mice. Cells double-positive for CD206 (red) and Arginase I (green) in mdx diaphragm are shown by immunofluorescence with specific antibodies. The relative increase in the number of these cells in the mdx diaphragm over time is shown. Bars = 50 μm.