Abstract P3002: Role Of Vascular Fibroblast Growth Factor Signaling In Group 3 Hypoxia-induced Pulmonary Hypertension

Abstract

Pulmonary hypertension (PH) is a debilitating disease characterized by pathologic changes in the pulmonary vasculature that increases pulmonary vascular resistance and leads to right heart failure. Group 3 PH is caused by lung disease and/or hypoxia, including bronchopulmonary dysplasia (BPD) and chronic obstructive lung disease (COPD), and is the second largest cause of mortality in PH patients. PH further increases the morbidity and mortality in both COPD and BPD patients. Fibroblast Growth Factor 2 (FGF2) and FGF Receptor 1 (FGFR1) expression is elevated in lung tissue of PH patients. To study the role of FGF signaling in the pathogenesis of group 3 PH, we developed a physiologically relevant mouse model in which mice are challenged with 10% hypoxia for 2 weeks. Following hypoxia exposure, cardiac catheterization is used to measure right ventricular (RV) pressure that mimics Group 3 PH. Lung tissue is then analyzed for histological and molecular changes. Our initial work showed that inactivation of FGFRs in endothelial cells (EC) worsened hypoxia-induced PH while expression of a constitutively active FGFR1 (caFGFR1) in ECs protected against hypoxia-induced PH. Here we hypothesize that FGF signaling may also affect the pathogenic response to hypoxia of vascular smooth muscle (VSMC), potentially by limiting vascular muscularization in response to hypoxia. We show that in vitro inhibition of FGF2 signaling in human pulmonary artery VSMCs reduced hypoxia-induced proliferation while promoting a contractile phenotype, and in vivo inactivation of FGFRs 1 and 2 worsened hypoxia-induced vascular remodeling. These data suggest the potential for a dual beneficial effect of activation of FGF signaling, both in regulating EC-VSMC interactions and directly preventing VSMC remodeling.