Integrative Multiomics in the Lung Reveals a Protective Role of Asporin in Pulmonary Arterial Hypertension.
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ABSTRACT: Integrative multiomics can elucidate pulmonary arterial hypertension (PAH) pathobiology but procuring human PAH lung samples is rare. Here, we leverage transcriptomic profiling and deep phenotyping of the largest multicenter PAH lung biobank to date (96 disease and 52 control) by integration with clinicopathologic data, genome-wide association studies, Bayesian regulatory networks, single-cell transcriptomics, and pharmacotranscriptomics. We identify two potentially protective gene network modules associated with vascular cells, and we validated ASPN, coding for asporin, as a key hub gene that is upregulated as a compensatory response to counteract PAH. Specifically, we find that asporin is upregulated in lungs and plasma of multiple independent PAH cohorts and correlates with reduced PAH severity. We show asporin inhibits proliferation and TGF-β/pSMAD2/3 signaling in pulmonary artery smooth muscle cells from PAH lungs. Finally, we demonstrate in Sugen-hypoxia rats that ASPN knockdown exacerbated PAH while recombinant asporin attenuated PAH. Our integrative systems biology approach to dissect the PAH lung transcriptome uncovered asporin as a novel protective target with therapeutic potential in PAH.
Project description:Pulmonary arterial hypertension (PAH) is a debilitating progressive disease characterized by high blood pressure in the pulmonary artery. Chrysin (5,7-dihydroxyflavone) is a phytochemical, which is a flavonoid widely present in plant sources. It is known that right ventricular dysfunction is the worst mortality predictor in patient with PAH. Recent studies have shown that chrysin improves hemodynamic parameters including right ventricular pressure, right ventricular hypertrophy, and pulmonary vascular remodeling in a rat model of chronic hypoxia-induced pulmonary hypertension. On the other hand, trimetazidine (TMZ) is an anti-ischemic agent widely used in the treatment of coronary artery disease. It has been reported that trimetazidine therapy for 3 months on top of standard PAH regime significantly improve right ventricular ejection fraction and functional capacity in patient with PAH. However, the effects of chrysin or trimetazidine on gene expression in lung of patient with PAH. Here, we performed that a comprehensive analysis of gene expression changes in lung tissues of sugen-received rats under hypoxic conditions, which is a model of PAH with chrysin or trimetazidine treatment using RNA sequencing (RNA-seq).
Project description:Pulmonary arterial hypertension (PAH) is a lethal vasculopathy associated with pulmonary arteries remodeling and right ventricle (RV) dysfunction. Epigenetic dysregulation, including altered DNA methylation, promotes PAH. However, the DNA methylation changes associated with PAH and their functional consequences on transcriptomic reprogramming remain unexplored in human PAH RV and lungs. We conducted an exploratory study in human lung and RV samples to characterize the DNA methylome and transcriptomic changes associated with PAH in both organs. Impaired DNA methylation landscape observed in PAH lungs and RV correlates with adverse pulmonary vascular remodeling, RV fibrosis, and markers of disease severity (e.g. NT-proBNP). PAH differentially methylated genes and differentially expressed transcripts regulate biological functions related to inflammation, fibrosis, heart contraction, blood vessel development. Moreover, we observed substantial lung/RV transcriptomic and methylomic changes overlap in PAH. Thus, PAH is associated with specific DNA methylation changes associated with the disease severity.
Project description:Objective: Pulmonary complications in systemic sclerosis (SSc), including pulmonary fibrosis (PF) and pulmonary arterial hypertension (PAH), are the leading cause of mortality. We compared the molecular fingerprint of SSc lung tissues and matching primary lung fibroblasts to those of normal donors, and patients with idiopathic pulmonary fibrosis (IPF) and idiopathic pulmonary arterial hypertension (IPAH). Methods: Lung tissues were obtained from 33 patients with SSc who underwent lung transplantation. Tissues and cells from a subgroup of SSc patients with predominantly PF or PAH were compared to those from normal donors, patients with IPF, or IPAH. Microarray data was analyzed using Efficiency Analysis for determination of optimal data processing methods. Real time PCR and immunohistochemistry were used to confirm differential levels of mRNA and protein, respectively. Results: We identified a consensus of 242 and 335 genes that were differentially expressed in lungs and primary fibroblasts, respectively. Enriched function groups in SSc-PF and IPF lungs included fibrosis, insulin-like growth factor signaling and caveolin-mediated endocytosis. Functional groups shared by SSc-PAH and IPAH lungs included antigen presentation, chemokine activity, and IL-17 signaling. Conclusion: Using microarray analysis on carefully phenotyped SSc and comparator lung tissues, we demonstrated distinct molecular profiles in tissues and fibroblasts of patients with SSc-associated lung disease compared to idiopathic forms of lung disease. Unique molecular signatures were generated that are disease- (SSc) and phenotype- (PF vs PAH) specific. These signatures provide new insights into pathogenesis and potential therapeutic targets for SSc lung disease. Lung tissues were obtained from 33 patients with SSc who underwent lung transplantation. Tissues and cells from a subgroup of SSc patients with predominantly PF or PAH were compared to those from normal donors, patients with IPF, or IPAH. Microarray data was analyzed using Efficiency Analysis for determination of optimal data processing methods. Real time PCR and immunohistochemistry were used to confirm differential levels of mRNA and protein, respectively.
Project description:Background:Pulmonary arterial hypertension (PAH) is a severe condition characterized by progressive vascular remodeling of small pulmonary arteries (PAs) causing sustained elevation of PA pressure, right ventricular failure and death. Similar to cancer cells, PA smooth muscle cells (PASMCs), which play a key role in pulmonary vascular remodeling, have adopted multiple mechanisms to sustain their survival and proliferation in the presence of stress. The histone methyltransferase G9a has been shown to exert oncogenic effects and to serve as a buffer against an exaggerated transcriptional response. Therefore, we hypothesized that G9a up-regulation in PAH plays a pivotal role in pulmonary vascular remodeling by maintaining the abnormal phenotype of PAH-PASMCs. Methods: G9alevels were measured in PAs and isolated PASMCs of PAH patients and animal models. Selective G9a pharmacological inhibitors were used in human PAH-PASMCs and in rodent PAH models (i.e.Fawn-Hooded rats and Sugen/Hypoxia-exposed mice). Results: We present evidence of increased expression of G9a in PASMCs from PAH patients as well as in remodeled PAs from animal models. We found that pharmacological inhibition of G9a activity using BIX01294 and UNC0642significantly reduces the prosurvival and proproliferative potentials of cultured PAH-PASMCs. Using RNA sequencing, further exploration revealed that G9a promotes extracellular matrix production and affords protection against the negative effects of an overactive stress response. Finally, we found that therapeutic treatment with BIX01294 reduced pulmonary vascular remodeling and lowered mean PA pressure in Fawn-Hooded rats. Treatment of Sugen/hypoxia-challenged mice with BIX01294 also improved pulmonary hemodynamics and right ventricular function. Conclusions:These findings suggest that G9a inhibition may represent a new therapeutic approach in PAH.
Project description:Objective: Pulmonary complications in systemic sclerosis (SSc), including pulmonary fibrosis (PF) and pulmonary arterial hypertension (PAH), are the leading cause of mortality. We compared the molecular fingerprint of SSc lung tissues and matching primary lung fibroblasts to those of normal donors, and patients with idiopathic pulmonary fibrosis (IPF) and idiopathic pulmonary arterial hypertension (IPAH). Methods: Lung tissues were obtained from 33 patients with SSc who underwent lung transplantation. Tissues and cells from a subgroup of SSc patients with predominantly PF or PAH were compared to those from normal donors, patients with IPF, or IPAH. Microarray data was analyzed using Efficiency Analysis for determination of optimal data processing methods. Real time PCR and immunohistochemistry were used to confirm differential levels of mRNA and protein, respectively. Results: We identified a consensus of 242 and 335 genes that were differentially expressed in lungs and primary fibroblasts, respectively. Enriched function groups in SSc-PF and IPF lungs included fibrosis, insulin-like growth factor signaling and caveolin-mediated endocytosis. Functional groups shared by SSc-PAH and IPAH lungs included antigen presentation, chemokine activity, and IL-17 signaling. Conclusion: Using microarray analysis on carefully phenotyped SSc and comparator lung tissues, we demonstrated distinct molecular profiles in tissues and fibroblasts of patients with SSc-associated lung disease compared to idiopathic forms of lung disease. Unique molecular signatures were generated that are disease- (SSc) and phenotype- (PF vs PAH) specific. These signatures provide new insights into pathogenesis and potential therapeutic targets for SSc lung disease.
Project description:Aims: Reactive oxygen species (ROS) play an important role in the pathogenesis of pulmonary arterial hypertension (PAH) and NADPH oxidases (NOXs) as sources of ROS are implicated in the development of the disease. We previously showed that NOX isozyme 1 (NOX1)-derived ROS contributes to pulmonary vascular endothelial cell (EC) proliferation in response to PAH triggers in vitro. However, whether and how NOX1 is involved in PAH in vivo have not been explored nor has NOX1 been examined as a viable and effective therapeutic disease target. Methods and Results: Herein, infusion of mice exposed to Sugen/hypoxia (10% O2) with a specific NOX1 inhibitor, NOXA1ds, delivered via osmotic minipumps (i.p.), significantly suppressed pathological changes in hemodynamic parameters characteristic of PAH. Furthermore, lungs of human patients with idiopathic PAH (iPAH) and exploratory RNA-seq analysis of hypoxic human pulmonary ECs, in which NOX1 was suppressed, were probed. The findings showed a clear indication of NOX1 in the promotion of both protein disulfide isomerase (PDI) and the unfolded protein response (UPR; in particular, the PERK arm of the pathway including eIF2α and ATF4) leading to proliferation. In aggregate, these results are consistent with a causal role for NOX1 in the development of mouse and human PAH and reveal a novel and mechanistic pathway by which NOX1 activates the UPR response during EC proliferation. Conclusion: NOX1 promotes phenotypic changes in ECs that are pivotal to proliferation and PAH through activation of the UPR. Taken together, our results are consistent with selective inhibition of NOX1 as a novel modality for attenuating PAH
Project description:Purpose:Pulmonary arterial hypertension secondary to congenital heart disease (CHD-PAH) with systemic-to-pulmonary shunt is characterized by proliferative vascular remodeling. Capillary morphogenesis gene-2 (CMG2) exhibits roles in cell proliferation and apoptosis. The purpose of this study was to determine the possible roles of CMG2 in the pathogenesis of systemic-to-pulmonary shunt induced PAH. Methods Lung tissue sections from CHD-PAH patients, systemic-to-pulmonary shunt induced PAH rat model, CMG2-/- rats, and PASMCs were used. Immunohistochemistry, real time polymerase chain reaction, Western blot, proliferation, apoptosis, and next generation sequencing (NGS) were performed in this study. Results CMG2 expression was reduced in lung tissues and pulmonary arterioles from Eisenmenger’s syndrome patient and rats with systemic-to-pulmonary shunt induced PAH. CMG2-/- rats exhibited heavier PAH and pulmonary vascular remodeling following exposure to systemic-to-pulmonary shunt for 8 weeks. Over-expression of CMG2 in cultured human PASMCs inhibited cell proliferation and promoted apoptosis, while knockdown of CMG2 promoted cell proliferation and inhibited apoptosis. A total of 1319 genes were found to be dysregulated in CMG2-/- rat lungs as detected by NGS. Biological processes influenced by these differentially expressed genes include regulation of blood vessel diameter, vasoconstriction, regulation of blood vessel size, vascular process in circulatory system, etc., and the most prominent pathway regulated is PI3K-Akt signaling pathway. Conclusion Our work identifies a novel role for CMG2 in systemic-to-pulmonary shunt induced PAH based on the findings that CMG2 deficiency could exacerbate systemic-to- pulmonary shunt induced vascular remodeling in the development of PAH. CMG2 may be a potential target for CHD-PAH treatment.
Project description:Vascular remodeling in pulmonary arterial hypertension (PAH) involves proliferation and migration of endothelial and smooth muscle cells, leading to obliterative vascular lesions. Previous studies have indicated that the endothelial cell proliferation is quasi-neoplastic, with evidence of monoclonality and instability of short DNA microsatellite sequences. To assess whether there is larger scale genomic instability, we performed genome-wide microarray copy number analysis on pulmonary artery endothelial (PAEC) and smooth muscle cells isolated from the lungs of PAH patients. Mosaic chromosomal abnormalities were detected in five of nine PAEC cultures from PAH lungs and zero of four controls. Fluorescent in situ hybridization analysis confirmed the presence of these abnormalities in vivo in two of three cases. One patient harbored a germline mutation of BMPR2, the primary genetic cause of PAH, and a somatic loss of chromosome-13, which constitutes a second hit in the same pathway by deleting Smad-8. In two female cases with mosaic loss of the X-chromosome, methylation analysis showed that the active X was deleted. Remarkably, one also showed completely skewed X-inactivation in the non-deleted cells, suggesting the PAEC population was clonal prior to the acquisition of the chromosome abnormality. Our data indicate a high frequency of genetically abnormal sub-clones within the lung vessels of patients with PAH and provide the first definitive evidence of a second genetic hit in a patient with a germline BMPR2 mutation. We propose that these chromosome abnormalities may confer a growth advantage and thus contribute to the progression of PAH. Cross-sectional study of genomic copy number in cells cultured from the lungs of PAH patients.
Project description:Although multiple gene and protein expression have been extensively profiled in human pulmonary arterial hypertension (PAH), the mechanism for the development and progression of pulmonary hypertension remains elusive. Analysis of the global metabolomic heterogeneity within the pulmonary vascular system leads to a better understanding of disease progression. Using a combination of high-throughput liquid-and-gas-chromatography-based mass spectrometry, we showed unbiased metabolomic profiles of disrupted glycolysis, increased TCA cycle, and fatty acid metabolites with altered oxidation pathways in the severe human PAH lung. The results suggest that PAH has specific metabolic pathways contributing to increased ATP synthesis for the vascular remodeling process in severe pulmonary hypertension. These identified metabolites may serve as potential biomarkers for the diagnosis of severe PAH. By profiling metabolomic alterations of the PAH lung, we reveal new pathogenic mechanisms of PAH in its later stage, which may differ from the earlier stage of PAH, opening an avenue of exploration for therapeutics that target metabolic pathway alterations in the progression of PAH. Global profiles were determined in human lung tissue and compared across 11 normal and 12 severe pulmonary arterial hypertension patients. Using a combination of microarray and high-throughput liquid-and-gas-chromatography-based mass spectrometry, we showed unbiased metabolomic profiles of disrupted glycolysis, increased TCA cycle, and fatty acid metabolites with altered oxidation pathways in the severe human PAH lung.