Chymase induces profibrotic response via transforming growth factor-beta 1/Smad activation in rat cardiac fibroblasts.

Mast cell-derived chymase is implicated in myocardial fibrosis (MF), but the underlying mechanism of intracellular signaling remains unclear. Transforming growth factor-beta 1 (TGF-beta1) is identified as the most important profibrotic cytokine, and Smad proteins are essential, but not exclusive downstream components of TGF-beta 1 signaling. Moreover, novel evidence indicates that there is a cross talk between Smad and mitogen-activated protein kinase (MAPK) signaling cascade.