Abstract 15053: Vascular Inflammation in Pulmonary Hypertension is Exacerbated by Litaf-dependent Pericyte Signaling

Abstract

Introduction: Pulmonary arterial hypertension (PAH) is a progressive disease which leads to right heart failure and death. Inflammation plays a key role in PAH pathogenesis as evidenced by inflammatory cell infiltrates around pulmonary vascular lesions and elevated patient serum pro-inflammatory cytokine levels. Pericytes are cells that provide mural support, maintain endothelial homeostasis and have immunomodulatory properties as evidenced by their production of cytokines and regulation of endothelial response to injury. Our group has shown that pericytes contribute to vascular remodeling and vessel loss in PAH, but their contribution to perivascular inflammation is unknown. Hypothesis: Lipopolysaccharide induced tumor necrosis factor activating factor (LITAF) positively regulates pericyte production of proinflammatory cytokines in PAH which influence activation of endothelial cells to engage in leukocyte recruitment. Methods: Healthy donor (HD) and PAH lung pericyte RNA-seq and microarray datasets were analyzed to identify candidate inflammatory pathways. Proteomic analysis was performed using Luminex assay followed by supervised machine learning. Quantitative PCR (qPCR) and western blot (WB) studies were conducted on HD and PAH pericytes exposed to serum starvation, hypoxia, LPS, and CoCl 2 (a HIF activator). Results: Network analysis based on RNA-seq, microarray, and Luminex assay data identified LITAF as a potential regulator of inflammatory gene expression. Compared to HD, abundant LITAF expression was visualized in human PAH perivascular lesions. WB of PAH pericytes showed a significant increase in nuclear LITAF compared to HD across all conditions. Pulmonary microvascular endothelial cells (PMVECs) incubated with media from PAH pericytes showed reduced cell-cell junctions and upregulated ICAM and VCAM compared to HD. Incubation of healthy PMVECs with supernatant from LITAF siRNA transfected HD and PAH pericytes showed a decrease in PMVEC proinflammatory cell markers. Conclusions: Our data suggest that LITAF-driven pericyte signaling could play a role in promoting vascular inflammation in PAH. We believe LITAF could serve as a potential new therapeutic target in PAH.