Transforming growth factor–ß in tissue fibrosis

TGF-ß is extensively implicated in the pathogenesis of fibrosis. In fibrotic lesions, spatially restricted generation of bioactive TGF-ß from latent stores requires the cooperation of proteases, integrins, and specialized extracellular matrix molecules. Although fibroblasts are major targets of TGF-ß, some fibrogenic actions may reflect activation of other cell types, including macrophages, epithelial cells, and vascular cells. TGF-ß–driven fibrosis is mediated through Smad-dependent or non-Smad pathways and is modulated by coreceptors and by interacting networks. This review discusses the role of TGF-ß in fibrosis, highlighting mechanisms of TGF-ß activation and signaling, the cellular targets of TGF-ß actions, and the challenges of therapeutic translation.