Fibrinogen as a damage-associated mitogenic signal for the renal fibroblast.

Fibroblast proliferation is central to the evolution of renal tubulointerstitial fibrosis. Using both in vivo and in vitro approaches, Sörensen et al. describe a role for fibrinogen as a cell-surface-receptor-mediated mitogen for renal fibroblasts. This interaction, likely to be initiated by injury and extravasation and to signal principally via Toll-like receptors, implicates fibrinogen in renal fibrosis beyond its textbook description as a scaffold precursor at the end of the coagulation cascade.