Abstract P3009: Fatty Acid-binding Proteins Promote Pulmonary Arterial Hypertension Via Upregulation Of Endothelial Glycolysis

Abstract

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.

Single-cell and Spatial Transcriptomics Identified Fatty Acid-binding Proteins Controlling Endothelial Glycolytic and Arterial Programming in Pulmonary Hypertension

“…Recent studies employing scRNA-seq analysis demonstrated that lung ECs contained arterial (expressing markers Cxcl12, Sparcl1, Edn1, Hey1 ) 34 , venous ( Prss23 , Vwf ) 34 , general capillary ECs ( Gpihbp1 , Plvap1 ), and aerocytes ( Car4, Ednrb ) 34,35 . Our recent studies demonstrated that general capillary EC derived arterial ECs were accumulated in the distal lung of PH mice and human IPAH patients 24 . Using similar markers to define EC subpopulations ( Extended Data Fig 5 ), our scRNA-seq data showed remarkable decreases in both general capillary EC and aerocyte proportion, but an increase in arterial EC proportion in CKO mice compared to WT mice, and the proportion of arterial ECs and capillary ECs were normalized in TKO mice compared to CKO mice ( Fig 7a-7c ).…”

“…( d ) Integration of scRNAseq and Visium spatial data revealed increased arterial ECs and decreased gCap ECs in the distal capillary bed of CKO mice, which was normalized in the TKO mice. The same WT and CKO lungs were used in our previous publication 24 . The visualization shows the predicted spatial distribution of arterial ECs and capillary ECs within the lungs.…”

“…Loss of distal capillaries and accumulation of pathogenic pulmonary arterial ECs with proliferative, anti-apoptotic and glycolytic phenotypes are hallmarks of PAH development 19–23 . Our recent studies demonstrated that arterial programming is evident in the distal microvasculature of PAH lungs and PH mice lung due to the general capillary ECs transition to arterial ECs through HIF-2α/Notch4 signaling 24 . In the present study, we found that among fatty acid chaperones, both FABP4 and FABP5 are dramatically induced in mouse PAECs from Egln1 Tie2Cre mice (CKO), a novel mouse model with severe PH and right heart failure 25,26 , and in human PAECs isolated from IPAH patients.…”