Abstract 4362992: Pulmonary arterial smooth muscle VPS34 activation is a shared molecular mechanism in adult pulmonary hypertension and congenital diaphragmatic hernia-associated pulmonary vascular remodeling

Introduction and Hypothesis: Congenital diaphragmatic hernia (CDH) is frequently associated with pulmonary hypertension (PH), characterized by pulmonary vascular remodeling, a leading cause of death in CDH patients. Despite advances in adult PH therapies, no targeted pharmacological interventions exist for CDH-associated pulmonary vascular remodeling, largely due to limited understanding of the molecular mechanisms involved. Building on prior findings that pulmonary arterial smooth muscle vacuolar protein sorting 34 (VPS34) activation by Akt promotes vascular remodeling in adult PH, we hypothesize that similar Akt-dependent VPS34 activation underlies CDH-associated pulmonary vascular remodeling. Methods and results: Mouse embryonic CDH was induced by Nitrofen/Bisdiamine (N/B) exposure at embryonic day 8.5 to recapitulate key features of human CDH. Morphological analysis of mouse embryonic lung tissues showed N/B-CDH is associated with significant pulmonary vascular remodeling, including reduced vessel counts (5.40±1.50 vs 4.20±2.40, per ROI, Control vs CDH, p<0.05), increased pulmonary arterial medial thickness (PAMT) (0.51±0.17 vs 0.65±0.16, Control vs CDH, p<0.0001), and decreased lumen area (0.32±0.27 vs 0.21±0.20, Control vs CDH, p<0.05). These structural changes correlated with pulmonary smooth muscle activation of VPS34, evidenced by decreased inhibitory Ser164 phosphorylation (2.02±0.076 vs 1.66±0.081, OD value, Control vs CDH, p<0.01) from immunohistochemical analysis. Similarly, we found that experimentally induced PH in adult mice exhibited pulmonary smooth muscle VPS34 activation (1.99±0.30 vs 1.42±0.05, OD value, Control vs PH, p<0.05), which is associated with significantly increased PAMT (0.31±0.02 vs 0.49±0.03, Control vs PH, p<0.001), right ventricular pressure (27.61±0.88 vs 40.81±1.59, mmHg, Control vs PH, p<0.001), and right ventricular hypertrophy (0.31±0.01 vs 0.44±0.02, Fulton-index, Control vs PH, p<0.001). Moreover, newly developed in silico SYNTERACT (SYNThetic data-driven protein-protein intERACtion Transformer) predicted that Akt-induced VPS34 activation could be mediated by protein phosphatases. Conclusion: Our preliminary evidence showed that CDH-associated pulmonary vascular remodeling shares similar Akt-dependent VPS34 activation mechanisms with those in adult PH. While further studies are needed, inhibiting VPS34 represents a potentially attractive therapeutic intervention for pulmonary vascular remodeling in CDH patients.