Abstract 14597: Beyond Sex Bias: The Uncharted Role of Rage Signaling in Pulmonary Arterial Hypertension

Abstract

Background: Pulmonary arterial hypertension (PAH) is a life-threatening disease that initiates in response to pulmonary artery endothelial cells (PAEC) damage followed by inadequate repair. The Receptor for Advanced Glycation Endproducts (RAGE) triggered upon the damage, plays a crucial role in vascular regeneration. However, its specific impact on PAH remains incompletely explored. Hypothesis: In this study, we investigated the sex-specific outcome of RAGE deletion on PAEC homeostasis. Methods: The effect of the global RAGE knockout (KO) on pulmonary hemodynamics, cardiac and endothelial function was studied disaggregated by sex in WT and RAGE KO rats. Endothelial integrity was evaluated via the expression of endothelial junction proteins, the activity of barrier disruptive signaling pathways, and in vivo pulmonary vascular permeability assay. To understand the significance of diminished RAGE signaling in male PAH, we measured membrane RAGE levels in untreated and Sugen/Hypoxia treated rats of both sexes and examined the publicly available single-cell transcriptomic profiles of human PAECs. Results: Male but not female RAGE KO rats developed a spontaneous PAH characterized by a significant increase in the right ventricle (RV) systolic pressure and RV hypertrophy. The PAH phenotype in males corresponded with a male-specific decrease in the expression of CD31 (WT vs. RAGE KO: 1.0 ± 0.07 vs. 0.1 ± 0.02, p <0001, N=6), activation of p38/RhoA signaling axis (p-p38 in WT vs. RAGE KO: 1.0 ± 0.2 vs. 3.2 ± 0.6, p=0.01, N=4), significant PAEC cytoskeletal rearrangement, and increased FITC-dextran extravasation, while female RAGE KOs remained unaffected. We also discovered that Sugen/Hypoxia treatment induced a substantial loss of membrane RAGE, specifically in males. Additionally, human PAEC transcriptomic data revealed that RAGE is expressed primarily in young females but not in males or older females. Conclusions: We conclude that the male sex associates with a reduced RAGE expression and signaling in PAEC, which is further diminished in PAH. The disruption in RAGE signaling, in turn, impairs the pulmonary endothelial barrier, instigates spontaneous PAH, and may contribute to the more severe phenotype observed in male PAH patients.