Figure 10.

A: Bleomycin (Bleo)-induced skin fibrosis is associated with accumulation of endogenous TLR4 ligands. TLR4-mutant mice and WT mice received daily s.c. injections of PBS or Bleo for 21 days. Lesional skin was harvested and examined by immunofluorescence. Representative images are shown. Original magnification, ×400. B: Cycle of fibrogenesis. Innate immune signaling via TLR4 switches self-limited repair into sustained fibrogenesis. Prolonged injury leads to tissue damage, and generation of endogenous TLR4 ligands, with activation of TLR4 and sustained fibroblast activation.