Fatty Acid-Binding Proteins Promote Pulmonary Arterial Hypertension via Upregulation of Endothelial Glycolysis

Introduction: Pulmonary arterial hypertension (PAH) is a disaster disease characterized by obliterative vascular remodeling and persistent increase of vascular resistance, leading to right heart failure and premature death. Understanding the cellular and molecular mechanisms will help develop novel therapeutic approaches for PAH patients. Hypothesis: We hypothesize that endothelial fatty acid metabolism is critical for obstructive vascular remodeling in the pathogenesis of PAH. Methods: A severe mouse model of PH Egln1 Tie2Cre mice were bred with Fabp45 -/- mice to generate Egln1 Tie2Cre / Fabp45 -/- mice. We applied single-cell RNA sequencing (scRNA-seq) to profile the pulmonary cells in Egln1 Tie2Cre mice and Egln1 Tie2Cre / Fabp45 -/- mice. Human hPAEC from idiopathic PAH patients and healthy donors were used to measure fatty acid-binding protein 4 and 5 (FABP4 and FABP5) expression. siRNA-mediated knockdown of FABP4 and FABP5 and lentivirus-mediated FABP4 and 5 overexpression were performed to study cell proliferation, apoptosis, and glycolysis. Results: scRNA-seq analysis demonstrated that both FABP4 and 5 were highly induced in the ECs of Egln1 Tie2Cre mice. PAECs from IPAH patients also showed higher expression of FABP4 and 5. Knockdown of FABP4-5 reduced EC proliferation, starvation-induced Caspase 3/7 activity, and glycolysis. Overexpression of FABP4-5 promoted EC glycolysis and proliferation. Genetic deletion of Fabp4 and 5 in Egln1 Tie2Cre mice exhibited a reduction of RVSP, RV hypertrophy, and reduction of EC glycolysis gene programming compared to Egln1 Tie2Cre mice. Conclusions: FABP4 and 5 control EC glycolysis and contribute to the development of PAH.