212 results found
Rhodes C, Wharton J, Swietlik E, et al., 2022, Using the plasma proteome for risk stratifying patients with pulmonary arterial hypertension, American Journal of Respiratory and Critical Care Medicine, Vol: 205, Pages: 1102-1111, ISSN: 1073-449X
Rationale: N-terminal pro-brain natriuretic peptide (NT-proBNP), a biomarker of cardiac origin, is used to risk stratify patients with pulmonary arterial hypertension (PAH). Its limitations include poor sensitivity to early vascular pathology. Other biomarkers of vascular or systemic origin may also be useful in the management of PAH.Objectives: Identify prognostic proteins in PAH which complement NT-proBNP and clinical risk scores.Methods: An aptamer-based assay (SomaScan-V4) targeting 4,152 proteins was used to measure plasma proteins in patients with idiopathic, heritable or drug-induced-PAH from the UK National Cohort of PAH (n=357) and the French EFORT study (n=79). Prognostic proteins were identified in discovery-replication analyses of UK samples. Proteins independent of 6-minute walk distance (6-MWD) and NT-proBNP entered LASSO modelling and the best combination in a single score was evaluated against clinical targets in EFORT.Measurements and Main Results: Thirty-one proteins robustly informed prognosis independent of NT-proBNP and 6-MWD in the UK Cohort. A weighted combination score of 6 proteins was validated at baseline (5-year mortality, AUC:0.73, 95%CI:0.63-0.85) and follow-up in EFORT (AUC:0.84, 95%CI:0.75-0.94, p=9.96x10-6). The protein score risk-stratified patients independent of established clinical targets and risk equations. The addition of the 6-protein model score to NT-proBNP improved prediction of 5-year outcomes from AUC:0.762 (0.702-0.821) to 0.818 (0.767-0.869) by ROC analysis (p=0.00426 for difference in AUC) in the UK replication and French samples combined. Conclusions: The plasma proteome informs prognosis beyond established factors in PAH and may provide a more sensitive measure of therapeutic response.
Thanaj M, Mielke J, McGurk K, et al., 2022, Genetic and environmental determinants of diastolic heart function, Nature Cardiovascular Research, Vol: 1, Pages: 361-371, ISSN: 2731-0590
Diastole is the sequence of physiological events that occur in the heart during ventricular filling and principally depends onmyocardial relaxation and chamber stiffness. Abnormal diastolic function is related to many cardiovascular disease processesand is predictive of health outcomes, but its genetic architecture is largely unknown. Here, we use machine learning cardiacmotion analysis to measure diastolic functional traits in 39,559 participants of the UK Biobank and perform a genome-wideassociation study. We identified 9 significant, independent loci near genes that are associated with maintaining sarcomericfunction under biomechanical stress and genes implicated in the development of cardiomyopathy. Age, sex and diabetes wereindependent predictors of diastolic function and we found a causal relationship between genetically-determined ventricularstiffness and incident heart failure. Our results provide insights into the genetic and environmental factors influencing diastolicfunction that are relevant for identifying causal relationships and potential tractable targets.
Harbaum L, Rhodes CJ, Wharton J, et al., 2022, Mining the plasma proteome for insights into the molecular pathology of pulmonary arterial hypertension., American Journal of Respiratory and Critical Care Medicine, ISSN: 1073-449X
RATIONALE: Pulmonary arterial hypertension (PAH) is characterized by structural remodelling of pulmonary arteries and arterioles. Underlying biological processes are likely reflected in a perturbation of circulating proteins. OBJECTIVES: To quantify and analyse the plasma proteome of PAH patients using inherited genetic variation to inform on underlying molecular drivers. METHODS: An aptamer-based assay was used to measure plasma proteins in 357 patients with idiopathic or heritable PAH, 103 healthy volunteers and 23 relatives of PAH patients. In discovery and replication subgroups, the plasma proteomes of PAH and healthy individuals were compared and the relationship to transplantation-free survival in PAH determined. To examine causal relationships to PAH, protein quantitative trait loci (pQTL) that influenced protein levels in the patient population were used as instruments for Mendelian randomisation (MR) analysis. MEASUREMENTS AND MAIN RESULTS: From 4,152 annotated plasma proteins, levels of 208 differed between PAH patients and healthy subjects and 49 predicted long-term survival. MR based on cis-pQTL located in proximity to the encoding gene for proteins that were prognostic and distinguished PAH from health estimated an adverse effect for higher levels of netrin-4 (odds ratio [OR] 1.55, 95%-confidence interval [CI] 1.16-2.08) and a protective effect for higher levels of thrombospondin-2 (OR 0.83, 95%-CI 0.74-0.94) on PAH. Both proteins tracked the development of PAH in previously healthy relatives and changes in thrombospondin-2 associated with pulmonary arterial pressure at disease onset. CONCLUSIONS: Integrated analysis of the plasma proteome and genome implicates two secreted matrix-binding proteins, netrin-4 and thrombospondin-2, in the pathobiology of PAH.
Howard LSGE, He J, Watson GMJ, et al., 2022, Supplementation with Iron in Pulmonary Arterial Hypertension: Two Randomized Crossover Trials (vol 18, pg 981, 2021), ANNALS OF THE AMERICAN THORACIC SOCIETY, Vol: 19, Pages: 703-703, ISSN: 1546-3222
Jones RJ, De Bie EMDD, Groves E, et al., 2022, Autoimmunity is a significant feature of idiopathic pulmonary arterial hypertension., American Journal of Respiratory and Critical Care Medicine, ISSN: 1073-449X
RATIONALE: Autoimmunity is thought to play a role in idiopathic pulmonary arterial hypertension (IPAH). It is not clear if this is causative or a bystander of disease and if it carries any prognostic or treatment significance. OBJECTIVE: To study autoimmunity in IPAH using a large cross-sectional cohort. METHODS: Assessment of the circulating immune cell phenotype was undertaken using flow cytometry and the profile of serum immunoglobulins was generated using a standardised multiplex array of 19 clinically validated autoantibodies in 473 cases and 946 controls. Additional GST-fusion array and ELISA data were used to identify a serum autoantibody to BMPR2. Clustering analyses and clinical correlations were employed to determine associations between immunogenicity and clinical outcomes. MEASUREMENTS AND MAIN RESULTS: Flow cytometric immune profiling demonstrates IPAH is associated with an altered humoral immune response in addition to raised IgG3. Multiplexed autoantibodies were significantly raised in IPAH, and clustering demonstrated three distinct clusters: 'high autoantibody', 'low autoantibody', and a small 'intermediate' cluster exhibiting high levels of RNP-complex. The high autoantibody cluster had worse haemodynamics but improved survival. A small subset of patients demonstrated immunoglobulin reactivity to BMPR2. CONCLUSIONS: This study establishes aberrant immune regulation and presence of autoantibodies as a key feature in the profile of a significant proportion of IPAH patients and is associated with clinical outcomes. This article is open access and distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
Kariotis S, Jammeh E, Swietlik EM, et al., 2021, Biological heterogeneity in idiopathic pulmonary arterial hypertension identified through unsupervised transcriptomic profiling of whole blood, Nature Communications, Vol: 12, Pages: 1-14, ISSN: 2041-1723
Idiopathic pulmonary arterial hypertension (IPAH) is a rare but fatal disease diagnosed by right heart catheterisation and the exclusion of other forms of pulmonary arterial hypertension, producing a heterogeneous population with varied treatment response. Here we show unsupervised machine learning identification of three major patient subgroups that account for 92% of the cohort, each with unique whole blood transcriptomic and clinical feature signatures. These subgroups are associated with poor, moderate, and good prognosis. The poor prognosis subgroup is associated with upregulation of the ALAS2 and downregulation of several immunoglobulin genes, while the good prognosis subgroup is defined by upregulation of the bone morphogenetic protein signalling regulator NOG, and the C/C variant of HLA-DPA1/DPB1 (independently associated with survival). These findings independently validated provide evidence for the existence of 3 major subgroups (endophenotypes) within the IPAH classification, could improve risk stratification and provide molecular insights into the pathogenesis of IPAH.
Sweatt AJ, Miyagawa K, Rhodes CJ, et al., 2021, Severe pulmonary arterial hypertension is characterized by increased neutrophil elastase and relative elafin deficiency, Chest, Vol: 160, Pages: 1442-1458, ISSN: 0012-3692
BACKGROUND: Preclinical evidence implicates neutrophil elastase (NE) in PAH pathogenesis, and the NE inhibitor elafin is under early therapeutic investigation. RESEARCH QUESTION: Are circulating NE and elafin levels abnormal in PAH and associated with clinical severity? STUDY DESIGN/METHODS: . In an observational Stanford University PAH cohort (N=249), plasma NE and elafin were measured in comparison to healthy controls (N=106) then related to clinical features and relevant ancillary biomarkers. Cox regression models were fitted with cubic spline functions to associate NE and elafin with survival. To validate prognostic relationships, we analyzed two United Kingdom cohorts (N=75, N=357). Mixed effects models evaluated NE and elafin changes during disease progression. Finally, we studied effects of NE/elafin balance on pulmonary artery endothelial cells (PAECs) from PAH patients. RESULTS: Relative to controls, patients had increased NE (205.1 [123.6-387.3] vs. 97.6 [74.4-126.6] ng/mL, P<0.0001) and decreased elafin (32.0 [15.3-59.1] vs. 45.5 [28.1-92.8] ng/mL, P<0.0001) independent of PAH subtype, illness duration, and therapies. Higher NE associated with worse symptom severity, shorter six-minute walk distance, higher NT-proBNP, greater right ventricular dysfunction, worse hemodynamics, increased circulating neutrophils, elevated cytokine levels, and lower blood BMPR2 expression. In Stanford patients, NE>168.5 ng/mL portended increased mortality risk after adjustment for known clinical predictors (HR 2.52, CI 1.36-4.65, P=0.003) or prognostic cytokines (HR 2.63, CI 1.42-4.87, P=0.001), and NE added incremental value to established PAH risk scores. Similar prognostic thresholds were identified in validation cohorts. Longitudinal NE changes tracked with clinical trends and outcomes. PAH-PAECs exhibited increased apoptosis and attenuated angiogenesis when exposed to NE at the level observed in patients' blood. Elafin rescued PAEC homeostasis, yet the required
Wilkins M, McKie M, Law M, et al., 2021, EXPRESS: Positioning Imatinib for Pulmonary Arterial Hypertension (PIPAH): A phase I/II design comprising dose finding and single arm efficacy Short title: Imatinib for PAH, Pulmonary Circulation, Vol: 11, Pages: 1-12, ISSN: 2045-8940
Pulmonary arterial hypertension is an unmet clinical need. Imatinib, a tyrosine kinase inhibitor, 200 to 400 mg daily reduces pulmonary artery pressure and increases functional capacity in this patient group, but is generally poorly tolerated at the higher dose. We have designed an open-label, single-arm clinical study to investigate whether there is a tolerated dose of imatinib that can be better targeted to patients who will benefit. The study consists of two parts. Part 1 seeks to identify the best tolerated dose of Imatinib in the range from 100 and up to 400 mg using a Bayesian Continuous Reassessment Method. Part 2 will measure efficacy after 24 weeks treatment with the best tolerated dose using a Simon’s two-stage design. The primary efficacy endpoint is a binary variable. For patients with a baseline pulmonary vascular resistance (PVR) >1000 dynes · s · cm−5, success is defined by an absolute reduction in PVR of ≥300 dynes · s · cm−5 at 24 weeks. For patients with a baseline PVR ≤1000 dynes · s · cm−5, success is a 30% reduction in PVR at 24 weeks. PVR will also be evaluated as a continuous variable by genotype as an exploratory analysis. Evaluating the response to that dose by genotype may inform a prospective biomarker-driven study.
Toshner M, Church C, Harbaum L, et al., 2021, Mendelian randomisation and experimental medicine approaches to IL-6 as a drug target in PAH, European Respiratory Journal, Vol: 59, Pages: 1-11, ISSN: 0903-1936
Inflammation and dysregulated immunity are important in the development of pulmonary arterial hypertension. Compelling preclinical data supports the therapeutic blockade of interleukin-6 signalling.We conducted an open-label phase-II study of intravenous tocilizumab (8 mg·kg-1) over 6 months in group 1 pulmonary arterial hypertension. Co-primary endpoints were safety, defined by incidence and severity of adverse events, and change in pulmonary vascular resistance. Separately, a Mendelian randomisation study was undertaken on 11,744 individuals with European ancestry including 2085 patients with idiopathic/heritable disease for the IL6R variant (rs7529229), known to associate with circulating IL6R levels.Twenty-nine patients (M/F 10/19; mean age 54.9[SD11.4]) were recruited. Nineteen had heritable/idiopathic and ten connective tissue disease associated pulmonary arterial hypertension. Six were withdrawn prior to drug administration. Twenty-three patients received at least one dose of tocilizumab. Tocilizumab was discontinued in 4 patients due to serious adverse events. There were no deaths. Despite evidence of target engagement in plasma interleukin-6 and C-reactive protein levels, both intention-to-treat and modified intention-to-treat analyses demonstrated no change in pulmonary vascular resistance. Inflammatory markers did not predict treatment response. Mendelian randomisation did not support an effect of the lead IL6R variant on risk of pulmonary arterial hypertension (OR 0.99, p=0.88).Adverse events were consistent with the known safety profile of tocilizumab. Tocilizumab did not show any consistent treatment effect.
Novoyatleva T, Rai N, Kojonazarov B, et al., 2021, Deficiency of Axl aggravates pulmonary arterial hypertension via BMPR2, COMMUNICATIONS BIOLOGY, Vol: 4
Errington N, Iremonger J, Pickworth JA, et al., 2021, A diagnostic miRNA signature for pulmonary arterial hypertension using a consensus machine learning approach, EBioMedicine, Vol: 69, ISSN: 2352-3964
BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare but life shortening disease, the diagnosis of which is often delayed, and requires an invasive right heart catheterisation. Identifying diagnostic biomarkers may improve screening to identify patients at risk of PAH earlier and provide new insights into disease pathogenesis. MicroRNAs are small, non-coding molecules of RNA, previously shown to be dysregulated in PAH, and contribute to the disease process in animal models. METHODS: Plasma from 64 treatment naïve patients with PAH and 43 disease and healthy controls were profiled for microRNA expression by Agilent Microarray. Following quality control and normalisation, the cohort was split into training and validation sets. Four separate machine learning feature selection methods were applied to the training set, along with a univariate analysis. FINDINGS: 20 microRNAs were identified as putative biomarkers by consensus feature selection from all four methods. Two microRNAs (miR-636 and miR-187-5p) were selected by all methods and used to predict PAH diagnosis with high accuracy. Integrating microRNA expression profiles with their associated target mRNA revealed 61 differentially expressed genes verified in two independent, publicly available PAH lung tissue data sets. Two of seven potentially novel gene targets were validated as differentially expressed in vitro in human pulmonary artery smooth muscle cells. INTERPRETATION: This consensus of multiple machine learning approaches identified two miRNAs that were able to distinguish PAH from both disease and healthy controls. These circulating miRNA, and their target genes may provide insight into PAH pathogenesis and reveal novel regulators of disease and putative drug targets.
Zhu N, Swietlik EM, Welch CL, et al., 2021, Rare variant analysis of 4241 pulmonary arterial hypertension cases from an international consortium implicates FBLN2, PDGFD, and rare de novo variants in PAH, Genome Medicine: medicine in the post-genomic era, Vol: 13, Pages: 1-18, ISSN: 1756-994X
BackgroundPulmonary arterial hypertension (PAH) is a lethal vasculopathy characterized by pathogenic remodeling of pulmonary arterioles leading to increased pulmonary pressures, right ventricular hypertrophy, and heart failure. PAH can be associated with other diseases (APAH: connective tissue diseases, congenital heart disease, and others) but often the etiology is idiopathic (IPAH). Mutations in bone morphogenetic protein receptor 2 (BMPR2) are the cause of most heritable cases but the vast majority of other cases are genetically undefined.MethodsTo identify new risk genes, we utilized an international consortium of 4241 PAH cases with exome or genome sequencing data from the National Biological Sample and Data Repository for PAH, Columbia University Irving Medical Center, and the UK NIHR BioResource – Rare Diseases Study. The strength of this combined cohort is a doubling of the number of IPAH cases compared to either national cohort alone. We identified protein-coding variants and performed rare variant association analyses in unrelated participants of European ancestry, including 1647 IPAH cases and 18,819 controls. We also analyzed de novo variants in 124 pediatric trios enriched for IPAH and APAH-CHD.ResultsSeven genes with rare deleterious variants were associated with IPAH with false discovery rate smaller than 0.1: three known genes (BMPR2, GDF2, and TBX4), two recently identified candidate genes (SOX17, KDR), and two new candidate genes (fibulin 2, FBLN2; platelet-derived growth factor D, PDGFD). The new genes were identified based solely on rare deleterious missense variants, a variant type that could not be adequately assessed in either cohort alone. The candidate genes exhibit expression patterns in lung and heart similar to that of known PAH risk genes, and most variants occur in conserved protein domains. For pediatric PAH, predicted deleterious de novo variants exhibited a significant burden compared to the background mutation rate (2.45×
Oldham WM, Hemnes AR, Aldred MA, et al., 2021, NHLBI-CMREF workshop report on pulmonary vascular disease classification: JACC state-of-the-art review., Journal of the American College of Cardiology, Vol: 77, Pages: 2040-2052, ISSN: 0735-1097
The National Heart, Lung, and Blood Institute and the Cardiovascular Medical Research and Education Fund held a workshop on the application of pulmonary vascular disease omics data to the understanding, prevention, and treatment of pulmonary vascular disease. Experts in pulmonary vascular disease, omics, and data analytics met to identify knowledge gaps and formulate ideas for future research priorities in pulmonary vascular disease in line with National Heart, Lung, and Blood Institute Strategic Vision goals. The group identified opportunities to develop analytic approaches to multiomic datasets, to identify molecular pathways in pulmonary vascular disease pathobiology, and to link novel phenotypes to meaningful clinical outcomes. The committee suggested support for interdisciplinary research teams to develop and validate analytic methods, a national effort to coordinate biosamples and data, a consortium of preclinical investigators to expedite target evaluation and drug development, longitudinal assessment of molecular biomarkers in clinical trials, and a task force to develop a master clinical trials protocol for pulmonary vascular disease.
Howard LSGE, He J, Watson GMJ, et al., 2021, Supplementation with iron in pulmonary arterial hypertension: two randomized crossover trials., Annals of the American Thoracic Society, Vol: 18, Pages: 981-988, ISSN: 1546-3222
RATIONALE: Iron deficiency, in the absence of anaemia, is common in patients with idiopathic and heritable pulmonary arterial hypertension (PAH) and is associated with a worse clinical outcome. Oral iron absorption may be impeded by elevated circulating hepcidin levels. The safety and benefit of parenteral iron replacement in this patient population is unclear. OBJECTIVES: To evaluate the safety and efficacy of parenteral iron replacement in pulmonary arterial hypertension. METHODS: In two randomised, double blind, placebo-controlled 12 week crossover studies, 39 patients in Europe received a single infusion of ferric carboxymaltose (Ferinject®) 1000 mg (or 15 mg/kg if weight < 66.7Kg) or saline as placebo and 17 patients in China received iron dextran (Cosmofer®) 20 mg iron/kg body weight or saline placebo. All patients had idiopathic or heritable PAH and iron deficiency at entry as defined by: a serum ferritin < 37 µg/l or iron < 10.3 µmol/l or transferrin saturations < 16.4%. RESULTS: Both iron treatments were well tolerated and improved iron status. Analysed separately and combined, there was no effect on any measure of exercise capacity (using cardiopulmonary exercise testing or 6 minute walk test) or cardio-pulmonary haemodynamics, as assessed by right heart catheterisation, cardiac magnetic resonance or plasma NT-proBNP, at 12 weeks. CONCLUSION: Iron repletion by administration of a slow release iron preparation as a single infusion to PAH patients with iron deficiency without overt anaemia was well tolerated but provided no significant clinical benefit at 12 weeks. Clinical trial registered with ClinicalTrials.gov (NCT01447628).
Wilkins MR, 2021, Personalized medicine for pulmonary hypertension: the future management of pulmonary hypertension requires a new taxonomy, Clinics in Chest Medicine, Vol: 42, Pages: 207-216, ISSN: 0272-5231
Russomanno G, Jo KB, Abdul-Salam V, et al., 2021, miR-150-PTPMT1-cardiolipin signaling in pulmonary arterial hypertension, Molecular Therapy : Nucleic Acids, Vol: 23, Pages: 142-153, ISSN: 2162-2531
Circulating levels of endothelial miR-150 are reduced in pulmonary arterial hypertension (PAH) and act as an independent predictor of patient survival, but links between endothelial miR-150 and vascular dysfunction are not well understood. We studied the effects of endothelial miR-150 supplementation and inhibition in PAH mice and cells from patients with idiopathic PAH. The role of selected mediators of miR-150 identified by RNA sequencing was evaluated in vitro and in vivo. Endothelium-targeted miR-150 delivery prevented the disease in Sugen/hypoxia mice, while endothelial knockdown of miR-150 had adverse effects. miR-150 target genes revealed significant associations with PAH pathways, including proliferation, inflammation, and phospholipid signaling, with PTEN-like mitochondrial phosphatase (PTPMT1) most markedly altered. PTPMT1 reduced inflammation and apoptosis and improved mitochondrial function in human pulmonary endothelial cells and blood-derived endothelial colony-forming cells from idiopathic PAH. Beneficial effects of miR-150 in vitro and in vivo were linked with PTPMT1-dependent biosynthesis of mitochondrial phospholipid cardiolipin and reduced expression of pro-apoptotic, pro-inflammatory, and pro-fibrotic genes, including c-MYB, NOTCH3, transforming growth factor β (TGF-β), and Col1a1. In conclusion, we are the first to show that miR-150 supplementation attenuates pulmonary endothelial damage induced by vascular stresses and may be considered as a potential therapeutic strategy in PAH.
Wu Y, Wharton J, Walters R, et al., 2021, The pathophysiological role of novel pulmonary arterial hypertension gene SOX17., European Respiratory Journal, Vol: 57, ISSN: 0903-1936
Pulmonary arterial hypertension (PAH) is a progressive disease predominantly targeting pre-capillary blood vessels. Adverse structural re-modelling and increased pulmonary vascular resistance result in cardiac hypertrophy and ultimately failure of the right ventricle. Recent whole genome and exome sequencing studies have identified SOX17 as a novel risk gene in PAH, with a dominant mode of inheritance and incomplete penetrance. Rare deleterious variants in the gene and more common variants in upstream enhancer sites have both been associated with the disease and a deficiency of SOX17 expression may predispose to PAH. This review aims to consolidate the evidence linking genetic variants in SOX17 to PAH and explores the numerous targets and effects of the transcription factor, focussing on the pulmonary vasculature and the pathobiology of PAH.
Swietlik EM, Greene D, Zhu N, et al., 2021, Bayesian inference associates rare KDR variants with specific phenotypes in pulmonary arterial hypertension., Circulation: Genomic and Precision Medicine, Vol: 14, Pages: 57-70, ISSN: 2574-8300
Background - Approximately 25% of patients with pulmonary arterial hypertension (PAH) have been found to harbor rare mutations in disease-causing genes. To identify missing heritability in PAH we integrated deep phenotyping with whole-genome sequencing data using Bayesian statistics. Methods - We analyzed 13,037 participants enrolled in the NIHR BioResource - Rare Diseases (NBR) study, of which 1,148 were recruited to the PAH domain. To test for genetic associations between genes and selected phenotypes of pulmonary hypertension (PH), we used the Bayesian rare-variant association method BeviMed. Results - Heterozygous, high impact, likely loss-of-function variants in the Kinase Insert Domain Receptor (KDR) gene were strongly associated with significantly reduced transfer coefficient for carbon monoxide (KCO, posterior probability (PP)=0.989) and older age at diagnosis (PP=0.912). We also provide evidence for familial segregation of a rare nonsense KDR variant with these phenotypes. On computed tomographic imaging of the lungs, a range of parenchymal abnormalities were observed in the five patients harboring these predicted deleterious variants in KDR. Four additional PAH cases with rare likely loss-of-function variants in KDR were independently identified in the US PAH Biobank cohort with similar phenotypic characteristics. Conclusions - The Bayesian inference approach allowed us to independently validate KDR, which encodes for the Vascular Endothelial Growth Factor Receptor 2 (VEGFR2), as a novel PAH candidate gene. Furthermore, this approach specifically associated high impact likely loss-of-function variants in the genetically constrained gene with distinct phenotypes. These findings provide evidence for KDR being a clinically actionable PAH gene and further support the central role of the vascular endothelium in the pathobiology of PAH.
Harbaum L, Rhodes CJ, Otero-Núñez P, et al., 2021, The application of 'omics' to pulmonary arterial hypertension, British Journal of Pharmacology, Vol: 178, Pages: 108-120, ISSN: 0007-1188
Recent genome-wide analyses of rare and common sequence variations have brought greater clarity to the genetic architecture of pulmonary arterial hypertension and implicated novel genes in disease development. Transcriptional signatures have been reported in whole lung tissue, pulmonary vascular cells and peripheral circulating cells. High-throughput platforms for plasma proteomics and metabolomics have identified novel biomarkers associated with clinical outcomes and provided molecular instruments for risk assessment. There are methodological challenges to integrating these datasets, coupled to statistical power limitations inherent to the study of a rare disease, but the expectation is that this strategy will reveal novel druggable targets and biomarkers that will open the way to personalised medicine. Here we review the current state-of-the-art and future promise of "omics" in the field of translational medicine in pulmonary arterial hypertension.
Schulz R, Wilkins M, 2021, Pulmonary hypertension with 2020 vision., British Journal of Pharmacology, Vol: 178, Pages: 3-5, ISSN: 0007-1188
Gassmann M, Cowburn A, Gu H, et al., 2021, Hypoxia-induced pulmonary hypertension - utilising experiments of nature, British Journal of Pharmacology, Vol: 178, Pages: 121-131, ISSN: 0007-1188
An increase in pulmonary artery pressure is a common observation in adult mammals exposed to global alveolar hypoxia. It is considered a maladaptive response that places an increased workload on the right ventricle. The mechanisms initiating and maintaining the elevated pressure are of considerable interest to understanding pulmonary vascular homeostasis. There is an expectation that identifying the key molecules in the integrated vascular response to hypoxia will inform potential drug targets. One strategy is to take advantage of experiments of nature; specifically, to understand the genetic basis for the inter-individual variation in the pulmonary vascular response to acute and chronic hypoxia. To date, detailed phenotyping of highlanders has focused on haematocrit and oxygen saturation rather that cardiovascular phenotypes. This review explores what we can learn from those studies with respect to the pulmonary circulation.
Ulrich A, Otero-Núñez P, Wharton J, et al., 2020, Expression quantitative trait locus mapping in pulmonary arterial hypertension, Genes, Vol: 11, ISSN: 2073-4425
Expression quantitative trait loci (eQTL) can provide a link between disease susceptibility variants discovered by genetic association studies and biology. To date, eQTL mapping studies have been primarily conducted in healthy individuals from population-based cohorts. Genetic effects have been known to be context-specific and vary with changing environmental stimuli. We conducted a transcriptome- and genome-wide eQTL mapping study in a cohort of patients with idiopathic or heritable pulmonary arterial hypertension (PAH) using RNA sequencing (RNAseq) data from whole blood. We sought confirmation from three published population-based eQTL studies, including the GTEx Project, and followed up potentially novel eQTL not observed in the general population. In total, we identified 2314 eQTL of which 90% were cis-acting and 75% were confirmed by at least one of the published studies. While we observed a higher GWAS trait colocalization rate among confirmed eQTL, colocalisation rate of novel eQTL reported for lung-related phenotypes was twice as high as that of confirmed eQTL. Functional enrichment analysis of genes with novel eQTL in PAH highlighted immune-related processes, a suspected contributor to PAH. These potentially novel eQTL specific to or active in PAH could be useful in understanding genetic risk factors for other diseases that share common mechanisms with PAH.
Swietlik EM, Ghataorhe P, Zalewska K, et al., 2020, Plasma metabolomics exhibit response to therapy in chronic thromboembolic pulmonary hypertension, European Respiratory Journal, Vol: 57, Pages: 1-14, ISSN: 0903-1936
Pulmonary hypertension is a condition with limited effective treatment options. Chronic thromboembolic pulmonary hypertension (CTEPH) is a notable exception with pulmonary endarterectomy (PEA) often proving curative. This study investigated the plasma metabolome of CTEPH patients, estimated reversibility to an effective treatment and explored the source of metabolic perturbations.We performed untargeted analysis of plasma metabolites in CTEPH patients compared to healthy controls and disease comparators. Changes in metabolic profile were evaluated in response to PEA. A subset of patients were sampled at three anatomical locations and plasma metabolite gradients calculated.We defined and validated altered plasma metabolite profiles in patients with CTEPH. 12 metabolites were confirmed by ROC analysis to distinguish CTEPH and both healthy (AUCs 0.64–0.94, all p<2×10−5) and disease controls (AUCs 0.58–0.77, all p<0.05. Many of the metabolic changes were notably similar to those observed in idiopathic pulmonary arterial hypertension (IPAH). Only five metabolites (5-methylthioadenosine, N1-methyladenosine, N1-methylinosine, 7-methylguanine, N-formylmethionine) distinguished CTEPH from chronic thromboembolic disease or IPAH. Significant corrections (15–100% of perturbation) in response to PEA were observed in some but not all metabolites. Anatomical sampling identified 188 plasma metabolites, with significant gradients in tryptophan, sphingomyelin, methionine, and Krebs cycle metabolites . Metabolites associated with CTEPH and gradients also showed significant associations with clinical measures of disease severity.We identified a specific metabolic profile that distinguishes CTEPH from controls and disease comparators, despite the observation that most metabolic changes were common to both CTEPH and IPAH patients. Plasma metabolite gradients implicate cardiopulmonary tissue metabolism of metabolites associated with PH and metabolites t
Bai W, Suzuki H, Huang J, et al., 2020, A population-based phenome-wide association study of cardiac and aortic structure and function, Nature Medicine, Vol: 26, Pages: 1654-1662, ISSN: 1078-8956
Differences in cardiac and aortic structure and function are associated with cardiovascular diseases and a wide range of other types of disease. Here we analyzed cardiovascular magnetic resonance images from a population-based study, the UK Biobank, using an automated machine-learning-based analysis pipeline. We report a comprehensive range of structural and functional phenotypes for the heart and aorta across 26,893 participants, and explore how these phenotypes vary according to sex, age and major cardiovascular risk factors. We extended this analysis with a phenome-wide association study, in which we tested for correlations of a wide range of non-imaging phenotypes of the participants with imaging phenotypes. We further explored the associations of imaging phenotypes with early-life factors, mental health and cognitive function using both observational analysis and Mendelian randomization. Our study illustrates how population-based cardiac and aortic imaging phenotypes can be used to better define cardiovascular disease risks as well as heart–brain health interactions, highlighting new opportunities for studying disease mechanisms and developing image-based biomarkers.
Rhodes C, Otero-Núñez P, Wharton J, et al., 2020, Whole blood RNA profiles associated with pulmonary arterial hypertension and clinical outcome, American Journal of Respiratory and Critical Care Medicine, Vol: 202, Pages: 586-594, ISSN: 1073-449X
Rationale: Idiopathic and hereditary pulmonary arterial hypertension (PAH) are rare but comprise a genetically heterogeneous patient group. RNA-sequencing linked to the underlying genetic architecture can be used to better understand the underlying pathology by identifying key signalling pathways and stratify patients more robustly according to clinical risk. Objectives: Using a three-stage design of RNA discovery, RNA validation/model construction and model validation to define a set of PAH-associated RNAs and a single summarising RNA model score. To define genes most likely to be involved in disease development, we performed Mendelian randomisation (MR) analysis. Methods: RNA-sequencing was performed on whole blood samples from 359 patients with idiopathic, heritable and drug-induced PAH and 72 age- and sex-matched healthy volunteers. The score was evaluated against disease severity markers including survival analysis using all-cause mortality from diagnosis. MR used known eQTL and summary statistics from a PAH GWAS. Measurements and Main Results: We identified 507 genes with differential RNA expression in PAH patients compared to controls. A model of 25 RNAs was able to distinguish PAH with 87% accuracy (AUC 95% CI: 0.791-0.945) in model validation. The RNA model score was associated with disease severity and long-term survival (p=4.66x10-6) in PAH. MR detected an association between SMAD5 levels and PAH disease susceptibility (OR:0.317, 95%CI:0.129-0.776, p=0.012). Conclusions: A whole blood RNA signature of PAH, which includes RNAs relevant to disease pathogenesis, associates with disease severity and identifies patients with poor clinical outcomes. Genetic variants associated with lower SMAD5 expression may increase susceptibility to PAH.
Sofianopoulou E, Church C, Coghlan G, et al., 2020, Deprivation and prognosis in patients with pulmonary arterial hypertension: missing the effect of deprivation on a rare disease?, European Respiratory Journal, Vol: 56, ISSN: 0903-1936
Turro E, Astle WJ, Megy K, et al., 2020, Whole-genome sequencing of patients with rare diseases in a national health system, Nature, Vol: 583, Pages: 96-102, ISSN: 0028-0836
Most patients with rare diseases do not receive a molecular diagnosis and the aetiological variants and causative genes for more than half such disorders remain to be discovered1. Here we used whole-genome sequencing (WGS) in a national health system to streamline diagnosis and to discover unknown aetiological variants in the coding and non-coding regions of the genome. We generated WGS data for 13,037 participants, of whom 9,802 had a rare disease, and provided a genetic diagnosis to 1,138 of the 7,065 extensively phenotyped participants. We identified 95 Mendelian associations between genes and rare diseases, of which 11 have been discovered since 2015 and at least 79 are confirmed to be aetiological. By generating WGS data of UK Biobank participants2, we found that rare alleles can explain the presence of some individuals in the tails of a quantitative trait for red blood cells. Finally, we identified four novel non-coding variants that cause disease through the disruption of transcription of ARPC1B, GATA1, LRBA and MPL. Our study demonstrates a synergy by using WGS for diagnosis and aetiological discovery in routine healthcare.
Sindi HA, Russomanno G, Satta S, et al., 2020, Therapeutic potential of KLF2-induced exosomal microRNAs in pulmonary hypertension (vol 33, pg 631, 2020), Nature Communications, Vol: 11, Pages: 1-1, ISSN: 2041-1723
Wilkins M, 2020, Pulmonary hypertension: proteins in the blood, Global Cardiology Science & Practice, Vol: 2020, Pages: e202007-e202007, ISSN: 2305-7823
The plasma proteome is rich in information. It comprises proteins that are secreted or lost from cells as they respond to their local environment. Changes in the constitution of the plasma proteome offer a relatively non-invasive report on the health of tissues. This is particularly true of the lung in pulmonary hypertension, given the large surface area of the pulmonary vasculature in direct communication with blood. So far, this is relatively untapped; we have relied on proteins released from the heart, specifically brain natriuretic peptide and troponin, to inform clinical management. New technology allows the measurement of a larger number of proteins that cover a broad range of molecular pathways in a single small aliquot. The emerging data will yield more than just new biomarkers of pulmonary hypertension for clinical use. Integrated with genomics and with the help of new bioinformatic tools, the plasma proteome can provide insight into the causative drivers of pulmonary vascular disease and guide drug development.
Thompson AAR, Wilkins MR, Wild JM, et al., 2020, Editorial: pulmonary hypertension: mechanisms and management, history and future, Frontiers in Medicine, Vol: 7, Pages: 1-3, ISSN: 2296-858X
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