Transcriptional Profiles of Pulmonary Artery Endothelial Cells in Pulmonary Hypertension
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ABSTRACT: Pulmonary arterial hypertension (PAH) is characterized by endothelial cell (EC) dysfunction. There are no data from living patients to inform whether differential gene expression of pulmonary artery ECs (PAECs) can discern disease subtypes, progression and pathogenesis. We aimed to further validate our previously described method to propagate ECs from right heart catheter (RHC) balloon tips and to perform additional PAEC phenotyping. We performed bulk RNA sequencing of PAECs from RHC balloons. Using unsupervised dimensionality reduction and clustering we compared transcriptional signatures from PAH to controls and other forms of pulmonary hypertension. Select PAEC samples underwent single cell and population growth characterization and anoikis quantification. Fifty-four specimens were analyzed from 49 subjects. The transcriptome appeared stable over limited passages. Six genes involved in sex steroid signaling, metabolism, and oncogenesis were significantly upregulated in PAH subjects as compared to controls. Genes regulating BMP and Wnt signaling, oxidative stress and cellular metabolism were differentially expressed in PAH subjects. Changes in gene expression tracked with clinical events in PAH subjects with serial samples over time. Functional assays demonstrated enhanced replication competency and anoikis resistance. Our findings recapitulate fundamental biological processes of PAH and provide new evidence of a cancer-like phenotype in ECs from the central vasculature of PAH patients. This “cell biopsy” approach may provide insight into EC heterogeneity within the lung and a therapeutic screening approach in PAH.
Project description:Pulmonary arterial hypertension (PAH) is a progressive disease in which pulmonary arterial (PA) endothelial cell (EC) dysfunction is associated with unrepaired DNA damage. BMPR2 is the most common mutant gene in PAH. We report that human PAEC with reduced BMPR2 have persistent DNA damage in room air after hypoxic exposure (reoxygenation), as do mice with EC deletion of Bmpr2 (EC-Bmpr2-/-) and persistent pulmonary hypertension. Similar findings are observed in PAEC with loss of the DNA damage sensor ATM, and in mice with Atm deleted in EC (EC-Atm-/-). Gene expression analysis of EC-Atm-/- and EC-Bmpr2-/- lung EC revealed reduced Foxf1, a transcription factor with relative selectivity for lung EC. Reducing FOXF1 in control PAEC induced DNA damage and impaired angiogenesis whereas transfection of FOXF1 in PAH PAEC repaired DNA damage and restored angiogenesis. Lung EC targeted delivery of Foxf1 to reoxygenated EC-Bmpr2-/- mice repaired DNA damage, induced angiogenesis and reversed pulmonary hypertension.
Project description:Dysfunction of pulmonary arterial endothelial cells (PAECs) is associated with the development and progression of vascular pathology. However, it remains unknown how pulmonary hypertension (PH) affects cellular composition and transcriptomic profile of pulmonary endothelium. Here, we have undertaken a single-cell, compartment specific approach to characterise alterations in PAECs associated with two different types of PH, i.e., pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with pulmonary fibrosis (PHPF). Our unbiased analysis showed that endothelium of medium / small caliber pulmonary arteries is composed of three subsets of endothelial cells (ECs). The analysis of healthy and PH endothelium revealed that the three populations are persistently represented in remodelled arteries. Additionally, an exploratory analysis of human aorta (AO) and coronary arteries (CA) endothelium revealed that, although similar gene expression patterns were noticeable, PAECs subpopulations proportions differs significantly from pulmonary arteries (PA) endothelium. To address whether EC heterogeneity is a prime feature of human endothelium, we also performed a similar analysis in a murine model of hypoxia, revealing that similar EC populations were evident in this animal model. Comparative analysis of EC subpopulations in healthy and PH EC identified a common genetic deregulation accompanying vascular remodelling. Even though murine EC displayed some similarities with human EC subpopulations, the intense re-programming associated with hypoxia associated vascular remodelling displayed significant differences compared to the human disease. Finally, in depth comparative analysis of PAH and PHPF EC highlighted the development of disease-specific transcriptomic alterations in the three populations. Therefore, characterisation of transcriptomic differences in the endothelial bed of PAH and PHPF patients can facilitate identification of novel, disease-specific therapeutic targets.
Project description:Rationale: Pulmonary arterial hypertension (PAH) is a devastating 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. Objectives: To determine whether upregulation of fatty-acid binding protein 4 and 5 (FABP4/5) is critical in pathogenesis of PAH. Methods: FABP4/5 expression was examined in pulmonary arterial endothelial cells (PAECs) and lung tissues from patients with idiopathic PAH and pulmonary hypertension (PH) rat models. Plasma proteome analysis was performed in human PAH samples. Echocardiography, hemodynamics, histology, and immunostaining were performed to evaluate the lung and heart PH phenotypes in Egln1Tie2Cre (CKO) mice and Egln1Tie2Cre/Fabp4-5-/- (TKO) mice. Measurement and Main Results: Both FABP4 and FABP5 were highly induced in ECs of CKO mice and PAECs from IPAH patients, and in whole lungs of PH rats. Plasma levels of FABP4/5 were upregulated in IPAH patients and directly correlated with severity of hemodynamics and biochemical parameters. Genetic deletion of both Fabp4 and 5 in CKO mice caused a reduction of right ventricular systolic pressure (RVSP) and RV hypertrophy, attenuated pulmonary vascular remodeling and prevented the right heart failure. Fabp4/5 deletion also normalized EC glycolysis, reduced ROS and HIF-2a expression, and decreased aberrant EC proliferation in CKO lungs. Conclusions: PH causes aberrant expression of FABP4/5 in pulmonary ECs which leads to enhanced EC glycolysis and hyperproliferation, contributing to the accumulation of arterial ECs and vascular remodeling and exacerbating the disease.
Project description:Human endogenous retroviral (HERV) proteins are induced by exogenous viruses or other factors that derepress HERV transcription and translation. Previously we showed that HERV-K envelope and deoxyuridine triphosphate nucleotidohydrolase (dUTPase) proteins are increased in monocytes and macrophages from patients with pulmonary arterial hypertension (PAH). Recombinant HERV-K dUTPase upregulates IL6 in pulmonary arterial endothelial cells (PAECs) and induces pulmonary hypertension in rats. However, it was not known how HERV-K dUTPase released from monocytes engages PAECs to upregulate IL6 or induces other PAH features of PAEC dysfunction. Here we report that HERV-K dUTPase recruits TLR4-myeloid differentiation primary response-88 to increase IL6 and SNAIL, the endothelial-mesenchymal transition (EndMT) transcription factor; HERV-K dUTPase interaction with melanoma cell adhesion molecule (MCAM) upregulates VCAM1. p38 and NF-kB are required to increase expression of all three genes, but in addition, pJNK-pSMAD3 is necessary for SNAIL upregulation, STAT1 for IL6, and pERK1/2-activating transcription factor-2 for VCAM1. Packaging of HERV-K dUTPase in monocyte-derived extracellular vesicles (EVs) induces SNAIL and subsequent EndMT in PAECs, IL6 and VCAM1. Mice infused with EVs from monocytes transfected with HERV-K dUTPase develop pulmonary hypertension. Thus, retroviral proteins delivered in EVs can overtake PAEC signaling and transcriptional machinery to induce dysfunction associated with PAH.
Project description:Pulmonary arterial hypertension (PAH) is a fatal disease characterized by a progressive increase in pulmonary artery pressure caused by pathological pulmonary artery remodeling. Here, we show that endothelial cell (EC) senescence plays a negative role in pulmonary hypertension via juxtacrine interaction with smooth muscle cells (SMCs). By using EC-specific progeroid mice that we recently generated, we discovered that EC progeria deteriorated vascular remodeling in the lungs, and exacerbated pulmonary hypertension in mice exposed to chronic hypoxia. Mechanistically, senescent ECs overexpressed Notch ligands, which resulted in increased Notch signaling and activated proliferation and migration capacities in neighboring SMCs. Pharmacological inhibition of Notch signaling reduced the effects of senescent ECs on SMCs functions in vitro, and improved the worsened pulmonary hypertension in EC-specific progeroid mice in vivo. Our findings show that EC senescence is a critical disease-modifying factor in PAH and that EC-mediated Notch signaling is a pharmacotherapeutic target for the treatment of PAH, particularly in the elderly.
Project description:Endothelial cell (EC) dysfunction plays a key role in the pathogenesis of pulmonary arterial hypertension (PAH). To avoid cell cultures and whole lung tissue samples, we have, for the first time, used CD31 antibody coated magnetic beads in conjunction with genome scale RNA expression microarrays to profile ECs in vivo at any stage of PAH. We hypothesized that targeting early stages of the disease would identify novel mediators of PAH and genes linked to bone morphogenetic protein receptor 2 (BMPR2) signaling. Rats were treated with either monocrotaline (60mg/kg) or saline as control with 4 animals in each experimental group. Gene expression profiling was performed on primary pulmonary endothelial cells directly after isolation from whole lung tissue 5 days after treatment.
Project description:Persistent pulmonary hypertension of the newborn (PPHN) occurs when pulmonary vascular resistance (PVR) fails to decrease at birth. Decreased angiogenesis in the lung contributes to the persistence of high PVR at birth. MicroRNAs (miRNAs) regulate gene expression through transcript binding and degradation. They were implicated in dysregulated angiogenesis in cancer and cardiovascular disease. We investigated whether altered miRNA levels contribute to impaired angiogenesis in PPHN. We used a fetal lamb model of PPHN induced by prenatal ductus arteriosus constriction and sham ligation as controls. We performed RNA sequencing of pulmonary artery endothelial cells (PAECs) isolated from control and PPHN lambs. We observed a differentially expressed miRNA profile in PPHN for organ development, cell-cell signaling, and cardiovascular function. MiR-34c was upregulated in PPHN PAECs compared to controls. Exogenous miR34c mimics decreased angiogenesis by control PAEC and anti-miR34c improved angiogenesis of PPHN PAEC in vitro. Notch1, a predicted target for miR-34c by bioinformatics, was decreased in PPHN PAECs, along with Notch1 downstream targets, Hey1 and Hes1. Exogenous miR-34c decreased Notch1 expression in control PAECs and anti-miR-34c restored Notch1 and Hes1 expression in PPHN PAECs. We conclude that increased miR-34c in PPHN contributes to impaired angiogenesis by decreasing Notch1 expression in PAECs."
Project description:Reduced bone morphogenetic protein receptor (BMPR)2 expression in patients with pulmonary arterial (PA) hypertension (PAH), can impair PA endothelial cell (EC) function. We now characterize, in human PAECs, a novel BMPR2-mediated transcriptionally active complex between peroxisome proliferator-activated receptor (PPAR) gamma and beta-catenin (BC), and show that disruption of this complex impairs BMP mediated HPAEC survival. Using whole genome wide ChIP-Chip promoter analysis we delineate PPARG-BC dependent transcription of target genes that include apelin. Comparison of ppar-gamma and beta-catenin occupancy on promoter regions from human pulmonary artery endothelial cells after either treatment with BMP2 or control. A total of 8 samples were created using NimbleGen human HG18 promoter arrays.
Project description:Pulmonary arterial hypertension (PAH) is a devastating and progressive disease with limited treatment options. Endothelial dysfunction plays a central role in development and progression of PAH, yet the underlying mechanisms are incompletely understood. The endosome-lysosome system is important to maintain cellular health and the small GTPase RAB7 regulates many functions of this system. Here, we explored the role of RAB7 in endothelial cell (EC) function and lung vascular homeostasis. We found reduced expression of RAB7 in ECs from PAH patients. Endothelial haploinsufficiency of RAB7 caused spontaneous PH in mice. Silencing of RAB7 in ECs induced broad changes in gene expression revealed via RNA sequencing and RAB7 silenced ECs showed impaired angiogenesis, expansion of a senescent cell fraction, combined with impaired endolysosomal trafficking and degradation, which suggests inhibition of autophagy at the pre-degradation level.
Project description:SRY-Box Transcription Factor 17 (SOX17) enhancers variants and mutations are found in patients with pulmonary arterial hypertension (PAH). In human PAH pulmonary endothelial cells, there is a significant downregulation of SOX17 expression. We hypothesized that SOX17 deficiency contributes to the pathogenesis of PAH and found that mice with endothelial specific disruption (ecKO Sox17) developed spontaneous pulmonary hypertension (PH) and exacerbated hypoxia-induced PH. Loss of SOX17 in lung ECs induced endothelial dysfunctions including upregulation of cell cycle programming and paracrine effect, proliferative and anti-apoptotic phenotypes, impaired cellular junction and BMP signaling. E2F Transcription Factor 1 (E2F1) signaling was showed to mediate the SOX17 deficiency-induced EC dysfunction. Pharmacological inhibition of E2F1 in ecKO Sox17 mice attenuated PH and cell cycle programming. Our study demonstrated that endothelial SOX17 deficiency induces PH through E2F1 and targeting E2F1 signaling represents a promising approach in PAH patients.