Profibrotic cytokine TGF-β1 increases endothelial progenitor cell angiogenic properties

Background: TGF-β1 is a profibrotic cytokine that plays a major role in vascular biology, and is known to regulate the phenotype and activity of various vascular cell populations. Because most fibrotic diseases, such as Idiopathic Pulmonary Fibrosis (IPF), are associated with vascular remodeling and since endothelial progenitor cells may be involved in this process, we investigated the impact of TGF-β1 modulation of endothelial progenitor cell angiogenic properties. Patients/ methods: TGF-β1 plasma levels were determined in 64 patients with IPF and compared to controls. The effect of TGF-β1 on angiogenesis was studied in vivo in a Matrigel plug model and in vitro on Endothelial Colony Forming Cells (ECFCs). We studied the effects of inhibiting the expression of the three main receptors of TGF-β1 in ECFCs using siRNA. Results: Total TGF-β1 plasma levels were significantly increased in patients with IPF compared to controls (P Conclusions: TGF-β1 is pro-angiogenic in vivo and induces ECFC angiogenic properties in vitro, suggesting that TGF-β1 may play a role during vascular remodeling in fibrotic disease states via endothelial progenitor cells.