Bone morphogenetic protein-3 is a negative regulator of transforming growth factor beta and fibrosis.

Fibrosis results in one-third of all deaths globally and is a major healthcare challenge. Fibrosis is scarring caused by the excess deposition of extracellular matrix proteins by fibroblasts. Inhibition of pathways downstream of transforming growth factor β (TGF-β) a pluripotent growth factor, has potent antifibrotic effects in different organs. Here we show that loss of bone morphogenetic protein (BMP-3) is a feature of kidney fibrosis, independent of the initiating injury, suggesting loss of this cytokine is a core fibrotic mechanism. TGF-β decreased BMP3 expression in human fibroblasts is possibly a feed-forward loop that contributes to increased and sustained TGF-β activity. Recombinant human BMP-3 reduced TGF-β induced fibroblast contraction, migration and invasion, pathways that lead to scarring and tissue stiffening. BMP-3 reduced TGF-β stimulated collagen cross-linking, and Ox-LDL receptor 1, a regulator of collagen deposition. BMP-3 inhibited TGF-β stimulated lysyl oxidase activity. Lysyl oxidase mediated collagen cross-linking is a critical process in TGF-β induced fibrosis. We propose that BMP-3 alters fibroblast responses to TGF-β, shifting the balance from fibrosis to repair. Recombinant human BMP-3 shows promise for development as a novel therapeutic for fibrosis.