Abstract 17218: CES1 Deficiency is Associated With Metabolic Reprograming and Endothelial Dysfunction in Pulmonary Arterial Hypertension

Abstract

Introduction: PAH is associated with loss of pulmonary microvessels & vascular remodeling. Metabolic reprogramming(MR) characterized by high glycolysis & reduced FAO is hallmark feature of PAH linked to oxidative stress, endothelial cell(EC) dysfunction & reduced angiogenesis. BMPR2 gene mutations promote MR; however, due to low penetrance, alterations in other genes are likely necessary for PAH development. We found Carboxylesterase 1 (CES1) is an ER enzyme involved in lipid metabolism & cellular detoxification with a potentially important role in MR & EC dysfunction in PAH. Hypothesis: Loss of CES1 leads to EC dysfunction through MR, lipotoxicity & oxidative stress & serves as a genetic modifier of BMPR2 in ECs Methods: Healthy/PAH ECs & lung tissues were obtained from transplants and commercial sources. Healthy ECs were transfected with siRNA/plasmid to knockdown/overexpress CES1. Mitochondrial & ER structure & function was assessed by confocal microscopy & proteomic assays. Metabolic flux in ECs was analyzed using the SeahorseXF. CES1 HET KO mice exposed to normoxia and hypoxia were studied & lungs were processed for scRNA-seq. Results: CES1 mRNA/protein expression was reduced in PAH ECs & lung vascular lesions. Compared to controls, siCES1 ECs have high apoptosis,reduced angiogenesis,increased ROS,mitochondrial fragmentation & ER stress. Lipid staining of siCES1 PMVECs demonstrates cytoplasmic lipid droplet accumulation correlating with reduced FAO and switch to glycolysis. Restoring CES1 expression reverses MR, reduces ROS & improves functional status of siCES1/PAH ECs. CES1 is a downstream target of BMPR2 under NRF2 transcriptional regulation & its loss exacerbates MR & dysfunction associated with BMPR2 loss that improves via CES1 restoration. Hemodynamic & scRNA-seq studies show that hypoxic CES1 HETKO mice develop more severe PH & demonstrate dysregulation of genes in key metabolic & angiogenic pathways. Conclusions: CES1 is essential for maintenance & repair of the pulmonary endothelium & acts as a key modifier of BMPR2 signaling. Limitations of current therapies to reverse EC dysfunction and prevent small vessel loss warrant therapeutic interventions that can restore CES1 expression and serve as a novel treatment approach for PAH.