Remodeling of active endothelial enhancers is associated with aberrant gene-regulatory networks in pulmonary arterial hypertension [ChIP-seq]
ABSTRACT: Pulmonary Arterial Hypertension (PAH) is a cardiovascular disease characterized by progressively increasing blood pressure as a result of obliteration and loss of pulmonary arteries. We have extracted pulmonary arterial endothelial cells from lungs of a cohort of PAH patients (n=10) and controls (n=9), cultured the cells for 3-5 passages, and performed chromatin (H3K27ac, H3K4me1, and H3K4me3 ChIP-Seq), expression (RNA-Seq) and chromatin interaction profiling (ChIA-PET). We observed a large-scale remodelling of the active chromatin landscape at enhancers while promoters and gene expression remained unchanged. Overall design: Profiling of chromatin states in pulmonary arterial endothelial cells of PAH-patients and donors.
Project description:Pulmonary Arterial Hypertension (PAH) is a cardiovascular disease characterized by progressively increasing blood pressure as a result of obliteration and loss of pulmonary arteries. We have extracted pulmonary arterial endothelial cells from lungs of a cohort of PAH patients (n=10) and controls (n=9), cultured the cells for 3-5 passages, and performed chromatin (H3K27ac, H3K4me1, and H3K4me3 ChIP-Seq), expression (RNA-Seq) and chromatin interaction profiling (ChIA-PET). We observed a large-scale remodelling of the active chromatin landscape at enhancers while promoters and gene expression remained unchanged. Overall design: chromatin interaction profiling (ChIA-PET)
Project description:Pulmonary Arterial Hypertension (PAH) is a cardiovascular disease characterized by progressively increasing blood pressure as a result of obliteration and loss of pulmonary arteries. We have extracted pulmonary arterial endothelial cells from lungs of a cohort of PAH patients (n=10) and controls (n=9), cultured the cells for 3-5 passages, and performed chromatin (H3K27ac, H3K4me1, and H3K4me3 ChIP-Seq), expression (RNA-Seq) and chromatin interaction profiling (ChIA-PET). We observed a large-scale remodelling of the active chromatin landscape at enhancers while promoters and gene expression remained unchanged. Overall design: Transcriptome profiling of pulmonary arterial endothelial cells of PAH-patients and donors.
Project description:The combination of chronic hypoxia and treatment of rats with the vascular endothelial growth factor (VEGF) receptor blocker, SU5416, induces pulmonary angio-obliteration, resulting in severe pulmonary arterial hypertension (PAH). Inflammation is thought to contribute to the pathology of PAH. Allergic inflammation caused by ovalbumin (OVA) immunization causes muscularization of pulmonary arteries, but not severe PAH. Whether disturbance of the immune system and allergic inflammation in the setting of lung endothelial cell apoptosis causes PAH is unknown. We investigated the effects of OVA-allergic inflammation on the development of PAH initiated by VEGF blockade-induced lung endothelial cell apoptosis. OVA-immunized rats were treated with SU5416 to induce pulmonary vascular endothelial cell apoptosis. The combination of OVA and SU5416 treatment resulted in severe angio-obilterative PAH, accompanied by increased IL-6 expression in the lungs. c-Kit(+) and Sca-1(+) cells were found in and around the lung vascular lesions. Pan-caspase inhibiton, dexamethasone treatment, and depletion of B-lymphocytes using an anti-CD20 antibody suppressed this remodeling. OVA immunization also increased lung tissue hypoxia-induced factor-1? and VEGF expression. Our results also suggest that the increased expression of hypoxia-induced factor-1? and IL-6 induced by the allergic lung inflammation may be a component of the pathogenesis of PAH.
Project description:Pulmonary arterial hypertension (PAH) is a rare, severe disease resulting from progressive obliteration of small-caliber pulmonary arteries by proliferating vascular cells. PAH can occur without recognized etiology (idiopathic PAH), be associated with a systemic disease or occur as a heritable form, with BMPR2 mutated in approximately 80% of familial and 15% of idiopathic PAH cases. We conducted a genome-wide association study (GWAS) based on 2 independent case-control studies for idiopathic and familial PAH (without BMPR2 mutations), including a total of 625 cases and 1,525 healthy individuals. We detected a significant association at the CBLN2 locus mapping to 18q22.3, with the risk allele conferring an odds ratio for PAH of 1.97 (1.59-2.45; P = 7.47 × 10(-10)). CBLN2 is expressed in the lung, and its expression is higher in explanted lungs from individuals with PAH and in endothelial cells cultured from explanted PAH lungs.
Project description:Pulmonary arterial hypertension (PAH) is a severe and incurable pulmonary vascular disease. One of the primary origins of PAH is pulmonary endothelial dysfunction leading to vasoconstriction, aberrant angiogenesis and smooth muscle cell proliferation, endothelial-to-mesenchymal transition, thrombosis and inflammation. Our objective was to study the epigenetic variations in pulmonary endothelial cells (PEC) through a specific pattern of DNA methylation. DNA was extracted from cultured PEC from patients with idiopathic PAH (n=11), heritable PAH (n=10) and controls (n=18). ). DNA methylation was assessed using the Illumina HumanMethylation450 Assay. After normalization, samples and probes were clustered according to their methylation profile. Differential clusters were functionally analysed using bioinformatics tools.
Project description:Pulmonary arterial hypertension (PAH) is characterized by vascular remodeling associated with obliteration of pulmonary arterioles and formation of plexiform lesions composed of hyperproliferative endothelial and vascular smooth-muscle cells. Here we describe a microRNA (miRNA)-dependent association between apelin (APLN) and fibroblast growth factor 2 (FGF2) signaling in pulmonary artery endothelial cells (PAECs). APLN deficiency in these cells led to increased expression of FGF2 and its receptor FGFR1 as a consequence of decreased expression of miR-424 and miR-503, which directly target FGF2 and FGFR1. miR-424 and miR-503 were downregulated in PAH, exerted antiproliferative effects in PAECs and inhibited the capacity of PAEC-conditioned medium to induce the proliferation of pulmonary artery smooth-muscle cells. Reconstitution of miR-424 and miR-503 in vivo ameliorated pulmonary hypertension in experimental models. These studies identify an APLN-dependent miRNA-FGF signaling axis needed for the maintenance of pulmonary vascular homeostasis.
Project description:Environmental and epigenetic factors often play an important role in polygenic disorders. However, how such factors affect disease-specific tissues at the molecular level remains to be understood. Here, we address this in pulmonary arterial hypertension (PAH). We obtain pulmonary arterial endothelial cells (PAECs) from lungs of patients and controls (n?=?19), and perform chromatin, transcriptomic and interaction profiling. Overall, we observe extensive remodeling at active enhancers in PAH PAECs and identify hundreds of differentially active TFs, yet find very little transcriptomic changes in steady-state. We devise a disease-specific enhancer-gene regulatory network and predict that primed enhancers in PAH PAECs are activated by the differentially active TFs, resulting in an aberrant response to endothelial signals, which could lead to disturbed angiogenesis and endothelial-to-mesenchymal-transition. We validate these predictions for a selection of target genes in PAECs stimulated with TGF-?, VEGF or serotonin. Our study highlights the role of chromatin state and enhancers in disease-relevant cell types of PAH.
Project description:Pulmonary endothelial dysfunction plays an integral role in mediating the initiation and progression of pulmonary vascular remodelling, an important feature of pulmonary arterial hypertension (PAH). Our aim was to decipher the gene expression program of endothelial cells derived from circulating endothelial progenitor (EPCs) to gain insight into the pathological process of PAH associated with systemic sclerosis (SSc), which is the most extreme vascular phenotype of this disease. We used microarrays to investigate the gene expression profile in late outgrowth EPC-derived endothelial cells issued from SSc-PAH patients, in comparison with SSc patients without PAH and healthy controls. Overall design: EPC-derived endothelial cells were isolated from peripheral blood of PAH-SSc patients, SSc patients without PAH and healthy control for RNA extraction and hybridization on Affymetrix microarrays. Gene expression profiles of EPC-derived endothelial cells were determined in basal conditions and also after hypoxic exposure.
Project description:BACKGROUND:We previously reported high-throughput RNA sequencing analyses that identified heightened expression of the chromatin architectural factor High Mobility Group AT-hook 1 (HMGA1) in pulmonary arterial endothelial cells (PAECs) from patients who had idiopathic pulmonary arterial hypertension (PAH) in comparison with controls. Because HMGA1 promotes epithelial-to-mesenchymal transition in cancer, we hypothesized that increased HMGA1 could induce transition of PAECs to a smooth muscle (SM)-like mesenchymal phenotype (endothelial-to-mesenchymal transition), explaining both dysregulation of PAEC function and possible cellular contribution to the occlusive remodeling that characterizes advanced idiopathic PAH. METHODS AND RESULTS:We documented increased HMGA1 in PAECs cultured from idiopathic PAH versus donor control lungs. Confocal microscopy of lung explants localized the increase in HMGA1 consistently to pulmonary arterial endothelium, and identified many cells double-positive for HMGA1 and SM22? in occlusive and plexogenic lesions. Because decreased expression and function of bone morphogenetic protein receptor 2 (BMPR2) is observed in PAH, we reduced BMPR2 by small interfering RNA in control PAECs and documented an increase in HMGA1 protein. Consistent with transition of PAECs by HMGA1, we detected reduced platelet endothelial cell adhesion molecule 1 (CD31) and increased endothelial-to-mesenchymal transition markers, ?SM actin, SM22?, calponin, phospho-vimentin, and Slug. The transition was associated with spindle SM-like morphology, and the increase in ?SM actin was largely reversed by joint knockdown of BMPR2 and HMGA1 or Slug. Pulmonary endothelial cells from mice with endothelial cell-specific loss of Bmpr2 showed similar gene and protein changes. CONCLUSIONS:Increased HMGA1 in PAECs resulting from dysfunctional BMPR2 signaling can transition endothelium to SM-like cells associated with PAH.
Project description:The pathophysiologic alterations of patients with pulmonary arterial hypertension (PAH) are diverse. We aimed to determine novel pathogenic pathways from circulating proteins in patients with PAH. Multianalyte profiling (MAP) was used to measure 90 specifically selected antigens in the plasma of 113 PAH patients and 51 control patients. Erythropoietin (EPO) functional activity was assessed via in vitro pulmonary artery endothelial cell networking and smooth muscle cell proliferation assays. Fifty-eight patients had idiopathic PAH, whereas 55 had other forms of PAH; 5 had heritable PAH, 18 had connective tissue disease (15 with scleroderma and 3 with lupus erythematosis), 13 had portopulmonary hypertension, 6 had PAH associated with drugs or toxins, and 5 had congenital heart disease. The plasma-antigen profile of PAH revealed increased levels of several novel biomarkers, including EPO. Immune quantitative and histochemical studies revealed that EPO not only was significantly elevated in the plasma of PAH patients but also promoted pulmonary artery endothelial cell network formation and smooth muscle cell proliferation. MAP is a hypothesis-generating approach to identifying novel pathophysiologic pathways in PAH. EPO is upregulated in the circulation and lungs of patients with PAH and may affect endothelial and smooth muscle cell proliferation.