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Balistrieri A, Makino A, Yuan JXJ. Pathophysiology and pathogenic mechanisms of pulmonary hypertension: role of membrane receptors, ion channels, and Ca 2+ signaling. Physiol Rev 2023; 103:1827-1897. [PMID: 36422993 PMCID: PMC10110735 DOI: 10.1152/physrev.00030.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 11/11/2022] [Accepted: 11/19/2022] [Indexed: 11/25/2022] Open
Abstract
The pulmonary circulation is a low-resistance, low-pressure, and high-compliance system that allows the lungs to receive the entire cardiac output. Pulmonary arterial pressure is a function of cardiac output and pulmonary vascular resistance, and pulmonary vascular resistance is inversely proportional to the fourth power of the intraluminal radius of the pulmonary artery. Therefore, a very small decrease of the pulmonary vascular lumen diameter results in a significant increase in pulmonary vascular resistance and pulmonary arterial pressure. Pulmonary arterial hypertension is a fatal and progressive disease with poor prognosis. Regardless of the initial pathogenic triggers, sustained pulmonary vasoconstriction, concentric vascular remodeling, occlusive intimal lesions, in situ thrombosis, and vascular wall stiffening are the major and direct causes for elevated pulmonary vascular resistance in patients with pulmonary arterial hypertension and other forms of precapillary pulmonary hypertension. In this review, we aim to discuss the basic principles and physiological mechanisms involved in the regulation of lung vascular hemodynamics and pulmonary vascular function, the changes in the pulmonary vasculature that contribute to the increased vascular resistance and arterial pressure, and the pathogenic mechanisms involved in the development and progression of pulmonary hypertension. We focus on reviewing the pathogenic roles of membrane receptors, ion channels, and intracellular Ca2+ signaling in pulmonary vascular smooth muscle cells in the development and progression of pulmonary hypertension.
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Affiliation(s)
- Angela Balistrieri
- Section of Physiology, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, California
- Harvard University, Cambridge, Massachusetts
| | - Ayako Makino
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California
| | - Jason X-J Yuan
- Section of Physiology, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, California
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2
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MacLean MR, Fanburg B, Hill N, Lazarus HM, Pack TF, Palacios M, Penumatsa KC, Wring SA. Serotonin and Pulmonary Hypertension; Sex and Drugs and ROCK and Rho. Compr Physiol 2022; 12:4103-4118. [PMID: 36036567 DOI: 10.1002/cphy.c220004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Serotonin is often referred to as a "happy hormone" as it maintains good mood, well-being, and happiness. It is involved in communication between nerve cells and plays a role in sleeping and digestion. However, too much serotonin can have pathogenic effects and serotonin synthesis is elevated in pulmonary artery endothelial cells from patients with pulmonary arterial hypertension (PAH). PAH is characterized by elevated pulmonary pressures, right ventricular failure, inflammation, and pulmonary vascular remodeling; serotonin has been shown to be associated with these pathologies. The rate-limiting enzyme in the synthesis of serotonin in the periphery of the body is tryptophan hydroxylase 1 (TPH1). TPH1 expression and serotonin synthesis are elevated in pulmonary artery endothelial cells in patients with PAH. The serotonin synthesized in the pulmonary arterial endothelium can act on the adjacent pulmonary arterial smooth muscle cells (PASMCs), adventitial macrophages, and fibroblasts, in a paracrine fashion. In humans, serotonin enters PASMCs cells via the serotonin transporter (SERT) and it can cooperate with the 5-HT1B receptor on the plasma membrane; this activates both contractile and proliferative signaling pathways. The "serotonin hypothesis of pulmonary hypertension" arose when serotonin was associated with PAH induced by diet pills such as fenfluramine, aminorex, and chlorphentermine; these act as indirect serotonergic agonists causing the release of serotonin from platelets and cells through the SERT. Here the role of serotonin in PAH is reviewed. Targeting serotonin synthesis or signaling is a promising novel alternative approach which may lead to novel therapies for PAH. © 2022 American Physiological Society. Compr Physiol 12: 1-16, 2022.
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Affiliation(s)
- Margaret R MacLean
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, Scotland
| | - Barry Fanburg
- Pulmonary, Critical Care and Sleep Division, Department of Medicine, Tufts Medical Center, Boston, Massachusetts, USA
| | - Nicolas Hill
- Pulmonary, Critical Care and Sleep Division, Department of Medicine, Tufts Medical Center, Boston, Massachusetts, USA
| | | | | | | | - Krishna C Penumatsa
- Pulmonary, Critical Care and Sleep Division, Department of Medicine, Tufts Medical Center, Boston, Massachusetts, USA
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3
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Santos-Gomes J, Gandra I, Adão R, Perros F, Brás-Silva C. An Overview of Circulating Pulmonary Arterial Hypertension Biomarkers. Front Cardiovasc Med 2022; 9:924873. [PMID: 35911521 PMCID: PMC9333554 DOI: 10.3389/fcvm.2022.924873] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/21/2022] [Indexed: 11/16/2022] Open
Abstract
Pulmonary arterial hypertension (PAH), also known as Group 1 Pulmonary Hypertension (PH), is a PH subset characterized by pulmonary vascular remodeling and pulmonary arterial obstruction. PAH has an estimated incidence of 15-50 people per million in the United States and Europe, and is associated with high mortality and morbidity, with patients' survival time after diagnosis being only 2.8 years. According to current guidelines, right heart catheterization is the gold standard for diagnostic and prognostic evaluation of PAH patients. However, this technique is highly invasive, so it is not used in routine clinical practice or patient follow-up. Thereby, it is essential to find new non-invasive strategies for evaluating disease progression. Biomarkers can be an effective solution for determining PAH patient prognosis and response to therapy, and aiding in diagnostic efforts, so long as their detection is non-invasive, easy, and objective. This review aims to clarify and describe some of the potential new candidates as circulating biomarkers of PAH.
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Affiliation(s)
- Joana Santos-Gomes
- UnIC@RISE, Department of Surgery and Physiology, Faculty of Medicine of the University of Porto, Porto, Portugal
| | - Inês Gandra
- UnIC@RISE, Department of Surgery and Physiology, Faculty of Medicine of the University of Porto, Porto, Portugal
| | - Rui Adão
- UnIC@RISE, Department of Surgery and Physiology, Faculty of Medicine of the University of Porto, Porto, Portugal
| | - Frédéric Perros
- Paris-Porto Pulmonary Hypertension Collaborative Laboratory (3PH), UMR_S 999, INSERM, Université Paris-Saclay, Paris, France
- Université Paris–Saclay, AP-HP, INSERM UMR_S 999, Service de Pneumologie et Soins Intensifs Respiratoires, Hôpital de Bicêtre, Le Kremlin Bicêtre, France
| | - Carmen Brás-Silva
- UnIC@RISE, Department of Surgery and Physiology, Faculty of Medicine of the University of Porto, Porto, Portugal
- Faculty of Nutrition and Food Sciences, University of Porto, Porto, Portugal
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Zhang F, Yang M, Xiao T, Hua Y, Chen Y, Xu S, Ni C. SLC6A4 gene L/S polymorphism and susceptibility to pulmonary arterial hypertension: a meta-analysis. J Int Med Res 2020; 48:300060520935309. [PMID: 32962488 PMCID: PMC7520923 DOI: 10.1177/0300060520935309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Objective To investigate the association between the solute carrier family 6 member 4 (SLC6A4) gene L/S polymorphism and pulmonary arterial hypertension (PAH). Methods The relevant literature was retrieved from the PubMed® database and the data were extracted. STATA® version 12.0 software was used to calculate pooled odds ratios (ORs) and 95% confidence intervals (CI). Results Eight case–control studies qualified for inclusion in the meta-analysis. These studies included 1215 cases and 936 control subjects. There was no significant association between the SLC6A4 gene L/S polymorphism and PAH risk in the total population (LL versus SS: OR 1.83, 95% CI 0.95, 3.51; LS versus SS: OR 1.37, 95% CI 0.93, 2.02; dominant model: OR 1.38, 95% CI 0.97, 1.97; recessive model: OR 1.54, 95% CI 0.84, 2.83). Subgroup analysis based on study quality scores and Hardy–Weinberg equilibrium also showed no significant association. Conclusion The findings of this meta-analysis suggest that the SLC6A4 gene L/S polymorphism is unlikely to be related to PAH risk. Well-designed studies with more participants will be required to validate these results.
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Affiliation(s)
- Feng Zhang
- School of Nursing, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Meiming Yang
- Department of Thyroid, Breast and Vascular Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Ting Xiao
- School of Nursing, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Yan Hua
- School of Nursing, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Yu Chen
- School of Nursing, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Shasha Xu
- School of Nursing, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Chunping Ni
- School of Nursing, Air Force Military Medical University, Xi'an, Shaanxi Province, China
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Jiao YR, Wang W, Lei PC, Jia HP, Dong J, Gou YQ, Chen CL, Cao J, Wang YF, Zhu YK. 5-HTT, BMPR2, EDN1, ENG, KCNA5 gene polymorphisms and susceptibility to pulmonary arterial hypertension: A meta-analysis. Gene 2019; 680:34-42. [DOI: 10.1016/j.gene.2018.09.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 09/05/2018] [Accepted: 09/11/2018] [Indexed: 12/13/2022]
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Analysis of Angiotensin Converting Enzyme, Endothelial Nitric Oxide Synthase & Serotonin Gene Polymorphisms among Atrial Septal Defect Subjects with and without Pulmonary Arterial Hypertension. J Cardiovasc Dev Dis 2018; 5:jcdd5030048. [PMID: 30231548 PMCID: PMC6162525 DOI: 10.3390/jcdd5030048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 09/14/2018] [Accepted: 09/17/2018] [Indexed: 11/17/2022] Open
Abstract
Genetic polymorphisms are variations in DNA sequences which can influence either disease susceptibility, severity, or prognosis. Pulmonary arterial hypertension (PAH) is one of the complications that occurs in certain patients who have atrial septal defect (ASD). This study seeks to determine the association of gene polymorphisms with the pathogenesis of PAH in ASD patients. This study was conducted on 30 ASD patients with PAH, and 50 ASD patients who were not diagnosed with PAH. All respondents were Malay. Patients were selected based on stringent inclusion and exclusion criteria. Molecular analyses were done to detect the genetic polymorphisms of angiotensin converting enzyme (ACE I/D), serotonin transporter (5-HTTLPR), endothelial nitric oxide synthase (eNOS) G894T, and eNOS 4b/4a. The genotypes of these genetic polymorphisms were determined using conventional PCR and PCR-RFLP methods. The PCR products were analysed using agarose gel electrophoresis. Statistical analysis was done using SPSS Version 22. Clinical characteristics, such as the diameter of ASD, mean arterial pressure (MAP), and mean pulmonary artery pressure (mPAP) differed significantly (p < 0.05). Based on the statistical analysis, ACE I/D, eNOS G894T, and eNOS 4b/4a do not contribute to the progression of PAH amongst ASD patients (p > 0.05). However, the L allele of the 5-HTTLPR gene polymorphism may have an affect on the development of PAH in ASD patients (p < 0.05).
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MacLean MMR. The serotonin hypothesis in pulmonary hypertension revisited: targets for novel therapies (2017 Grover Conference Series). Pulm Circ 2018; 8:2045894018759125. [PMID: 29468941 PMCID: PMC5826007 DOI: 10.1177/2045894018759125] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Increased synthesis of serotonin and/or activity of serotonin in pulmonary arteries has been implicated in the pathobiology of pulmonary arterial hypertension (PAH). The incidence of PAH associated with diet pills such as aminorex, fenfluramine, and chlorphentermine initially led to the “serotonin hypothesis of pulmonary hypertension.” Over the last couple of decades there has been an accumulation of convincing evidence that targeting serotonin synthesis or signaling is a novel and promising approach to the development of novel therapies for PAH. Pulmonary endothelial serotonin synthesis via tryptophan hydroxlase 1 (TPH1) is increased in patients with PAH and serotonin can act in a paracrine fashion on underlying pulmonary arterial smooth muscle cells (PASMCs), In humans, serotonin can enter PASMCs via the serotonin transporter (SERT) or activate the 5-HT1B receptor; 5-HT1B activation and SERT activity cooperate to induce PASMC contraction and proliferation via activation of downstream proliferative and contractile signaling pathways. Here we will review the current status of the serotonin hypothesis and discuss potential and novel therapeutic targets.
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Affiliation(s)
- Margaret Mandy R MacLean
- Research Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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8
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Austin ED, West J, Loyd JE, Hemnes AR. Translational Advances in the Field of Pulmonary Hypertension Molecular Medicine of Pulmonary Arterial Hypertension. From Population Genetics to Precision Medicine and Gene Editing. Am J Respir Crit Care Med 2017; 195:23-31. [PMID: 27398627 DOI: 10.1164/rccm.201605-0905pp] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
| | - James West
- 2 Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - James E Loyd
- 2 Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Anna R Hemnes
- 2 Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
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9
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Changes in gene expression profiles in patients with pulmonary arterial hypertension associated with scleroderma treated with tadalafil. Semin Arthritis Rheum 2017; 46:465-472. [DOI: 10.1016/j.semarthrit.2016.05.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 05/24/2016] [Accepted: 05/27/2016] [Indexed: 11/21/2022]
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10
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Why drugs fail in clinical trials in pulmonary arterial hypertension, and strategies to succeed in the future. Pharmacol Ther 2016; 164:195-203. [DOI: 10.1016/j.pharmthera.2016.04.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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11
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Identification of multiple ACVRL1 mutations in patients with pulmonary arterial hypertension by targeted exome capture. Clin Sci (Lond) 2016; 130:1559-69. [PMID: 27316748 DOI: 10.1042/cs20160247] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/17/2016] [Indexed: 11/17/2022]
Abstract
Pulmonary artery hypertension (PAH) is characterized as sustained elevation of pressure in the pulmonary vascular system that is attributable to a variety of causes. More than a dozen genes have previously been proposed as being associated with PAH. To examine potential mutations of these genes in patients with PAH, we developed a targeted exome kit containing 22 PAH-associated genes for genetic screens of 80 unrelated patients with PAH. As a result, we identified 16 different mutations in the BMPR2 gene and four different mutations in ACVRL1, the gene for activin receptor-like kinase-1 (ACVRL1). However, no deleterious mutations were found in the remaining 20 genes. In the present study, we provided detailed characterization of the ACVRL1 mutations in four pedigrees, including two novel missense mutations (c.676G>A, p.V226M; c.955G>C, p.G319R) and two recurrent mutations (c.1231C>T, p.R411W; c.1450C>T, p.R484W). Furthermore, we showed that markedly reduced Smad1/5 phosphorylation levels and reduced activities of luciferase reporters in each of the four ACVRL1 mutant-transfected NIH-3T3 cells. Therefore, our findings demonstrated that missense mutations of ACVRL1 identified in the present study significantly affected the bone morphogenetic protein 9 (BMP-9) pathway, implicating PAH pathogenesis. Detailed genotype–phenotype correlation analysis revealed initial symptoms of hereditary haemorrhagic telangiectasia (HHT) in some of the patients, suggesting the importance of sequencing molecular markers for early identification and intervention of individuals at risk for PAH and potential HHT. We developed a customized exome sequencing system to identify mutations in these PAH-associated genes, and found two novel missense mutations and two recurrent mutations in the ACVRL1 gene in four unrelated Chinese families; we also determined hypomorphic alleles using functional studies.
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12
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Austin ED, Loyd JE. Toward Precision Medicine in Pulmonary Arterial Hypertension. Am J Respir Crit Care Med 2016; 192:1272-4. [PMID: 26623685 DOI: 10.1164/rccm.201508-1607ed] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Eric D Austin
- 1 Department of Pediatrics Vanderbilt University Medical Center Nashville, Tennessee
| | - James E Loyd
- 2 Department of Medicine Vanderbilt University Medical Center Nashville, Tennessee
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13
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Moyer AM, Walker DL, Avula R, Lapid MI, Kung S, Bryant SC, Edwards KK, Black JL, Karpyak VM, Shinozaki G, Jowsey-Gregoire SG, Ehlers SL, Romanowicz M, Litzow MR, Hogan WJ, Rundell JR, Hooten WM, Baudhuin LM. Relationship of genetic variation in the serotonin transporter gene (SLC6A4) and congenital and acquired cardiovascular diseases. Genet Test Mol Biomarkers 2015; 19:115-23. [PMID: 25671637 DOI: 10.1089/gtmb.2014.0250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Recent reports have suggested an association between variation in the serotonin transporter and primary pulmonary hypertension and myocardial infarction. We set out to determine whether these associations were present in a population of patients who underwent SLC6A4 genotyping and to explore whether genetic variation in the serotonin transporter might be also associated with other cardiovascular functional and structural abnormalities. Included were 3473 patients who were genotyped for the SLC6A4 5HTTLPR polymorphism and a subset for rs25531 (n=816) and STin2 (n=819). An association was observed between 5HTTLPR and primary pulmonary hypertension (p=0.0130), anomalies of the cerebrovascular system (p<0.0001), and other anomalies of great veins (p=0.0359). The combined 5HTTLPR and rs25531 genotype was associated with tachycardia (p=0.0123). There was an association of the STin2 genotype with abnormal electrocardiogram (ECG) (p=0.0366) and abnormal cardiac study (0.0311). Overall, these results represent a step toward the understanding of the impact of SLC6A4 variation on cardiovascular pathology.
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Affiliation(s)
- Ann M Moyer
- 1 Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota
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Tissue transglutaminase promotes serotonin-induced AKT signaling and mitogenesis in pulmonary vascular smooth muscle cells. Cell Signal 2014; 26:2818-25. [PMID: 25218191 DOI: 10.1016/j.cellsig.2014.09.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Accepted: 09/02/2014] [Indexed: 01/06/2023]
Abstract
Tissue transglutaminase 2 (TG2) is a multifunctional enzyme that cross-links proteins with monoamines such as serotonin (5-hydroxytryptamine, 5-HT) via a transglutamidation reaction, and is associated with pathophysiologic vascular responses. 5-HT is a mitogen for pulmonary artery smooth muscle cells (PASMCs) that has been linked to pulmonary vascular remodeling underlying pulmonary hypertension development. We previously reported that 5-HT-induced PASMC proliferation is inhibited by the TG2 inhibitor monodansylcadaverine (MDC); however, the mechanisms are poorly understood. In the present study we hypothesized that TG2 contributes to 5-HT-induced signaling pathways of PASMCs. Pre-treatment of bovine distal PASMCs with varying concentrations of the inhibitor MDC led to differential inhibition of 5-HT-stimulated AKT and ROCK activation, while p-P38 was unaffected. Concentration response studies showed significant inhibition of AKT activation at 50 μM MDC, along with inhibition of the AKT downstream targets mTOR, p-S6 kinase and p-S6. Furthermore, TG2 depletion by siRNA led to reduced 5-HT-induced AKT activation. Immunoprecipitation studies showed that 5-HT treatment led to increased levels of serotonylated AKT and increased TG2-AKT complex formations which were inhibited by MDC. Overexpression of TG2 point mutant cDNAs in PASMCs showed that the TG2 C277V transamidation mutant blunted 5-HT-induced AKT activation and 5-HT-induced PASMC mitogenesis. Finally, 5-HT-induced AKT activation was blunted in SERT genetic knock-out rat cells, but not in their wild-type counterpart. The SERT inhibitor imipramine similarly blocked AKT activation. These results indicate that TG2 contributes to 5-HT-induced distal PASMC proliferation via promotion of AKT signaling, likely via its serotonylation. Taken together, these results provide new insight into how TG2 may participate in vascular smooth muscle remodeling.
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Abstract
Pulmonary arterial hypertension (PAH) is a progressive and fatal disease for which there is an ever-expanding body of genetic and related pathophysiological information on disease pathogenesis. Many germline gene mutations have now been described, including mutations in the gene coding bone morphogenic protein receptor type 2 (BMPR2) and related genes. Recent advanced gene-sequencing methods have facilitated the discovery of additional genes with mutations among those with and those without familial forms of PAH (CAV1, KCNK3, EIF2AK4). The reduced penetrance, variable expressivity, and female predominance of PAH suggest that genetic, genomic, and other factors modify disease expression. These multi-faceted variations are an active area of investigation in the field, including but not limited to common genetic variants and epigenetic processes, and may provide novel opportunities for pharmacological intervention in the near future. They also highlight the need for a systems-oriented multi-level approach to incorporate the multitude of biological variations now associated with PAH. Ultimately, an in-depth understanding of the genetic factors relevant to PAH provides the opportunity for improved patient and family counseling about this devastating disease.
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Affiliation(s)
- Eric D Austin
- From the Division of Allergy, Pulmonary, and Immunology Medicine, Department of Pediatrics (E.D.A.) and Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine (J.E.L.), Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Vanderbilt University, Nashville, TN.
| | - James E Loyd
- From the Division of Allergy, Pulmonary, and Immunology Medicine, Department of Pediatrics (E.D.A.) and Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine (J.E.L.), Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Vanderbilt University, Nashville, TN
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16
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Rajkumar R, Ahmad F. The genomic complexity underlying pulmonary arterial hypertension: from mendel to networks. Am J Respir Crit Care Med 2014; 189:1152-4. [PMID: 24832737 DOI: 10.1164/rccm.201403-0556ed] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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17
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Dempsie Y, Maclean MR. Role of the serotonin transporter in pulmonary arterial hypertension. Expert Rev Clin Pharmacol 2014; 1:749-57. [PMID: 24410605 DOI: 10.1586/17512433.1.6.749] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Pulmonary arterial hypertension is a disease in which pulmonary arterial pressure is raised, leading to right heart failure. Survival is poor despite current therapeutic strategies. The 'serotonin hypothesis of pulmonary arterial hypertension' arose in the 1960s following an 'epidemic' of pulmonary arterial hypertension in women taking the indirect serotinergic agonist aminorex as an anorexigen. In the 1980s, the hypothesis was revisited following the occurrence of pulmonary arterial hypertension associated with the use of fenfluramines as anorexigens; these are also indirect serotinergic agents. Research has identified changes in serotonin synthesis, serotonin receptor activation and serotonin uptake via the serotonin transporter in experimental and clinical pulmonary arterial hypertension. This review will discuss our current understanding of this serotonin hypothesis with particular reference to the role of the serotonin transporter.
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Affiliation(s)
- Yvonne Dempsie
- Integrative and Systems Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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18
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Brenner L, Chung WK. Clinical and molecular genetic features of hereditary pulmonary arterial hypertension. Compr Physiol 2013; 1:1721-8. [PMID: 23733703 DOI: 10.1002/cphy.c100063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Pulmonary arterial hypertension (PAH) is a rare disorder that may be hereditary (HPAH), idiopathic (IPAH), or associated with either drug-toxin exposures or other medical conditions. Familial cases have long been recognised and are usually due to mutations in the bone morphogenetic protein receptor type 2 gene (BMPR2), or, much less commonly, two other members of the transforming growth factor-β superfamily, activin-like kinase-type 1 (ALK1), and endoglin (ENG), which are associated with hereditary hemorrhagic telangiectasia. In addition, approximately 20% of patients with IPAH carry mutations in BMPR2. Clinical testing for BMPR2 mutations is available and may be offered to HPAH and IPAH patients but should be preceded by genetic counselling, since lifetime penetrance is only 10% to 20%, and there are currently no known effective preventative measures. Identification of a familial mutation can be valuable in reproductive planning and identifying family members who are not mutation carriers and thus will not require lifelong surveillance. With advances in genomic technology and with international collaborative efforts, genome-wide association studies will be conducted to identify additional genes for HPAH, genetic modifiers for BMPR2 penetrance, and genetic susceptibility to IPAH. In addition, collaborative studies of BMPR2 mutation carriers should enable identification of environmental modifiers, biomarkers for disease development and progression, and surrogate markers for efficacy end points in clinical drug development, thereby providing an invaluable resource for trials of PAH prevention.
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Affiliation(s)
- Laura Brenner
- Department of Pediatrics, Columbia University Medical Center, New York, New York, USA
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19
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Zhang H, Xu M, Xia J, Qin RY. Association between serotonin transporter (SERT) gene polymorphism and idiopathic pulmonary arterial hypertension: a meta-analysis and review of the literature. Metabolism 2013; 62:1867-75. [PMID: 24075737 DOI: 10.1016/j.metabol.2013.08.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 08/18/2013] [Accepted: 08/19/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Idiopathic pulmonary arterial hypertension (IPAH) is a rare and often fatal disease of unknown etiology. Serotonin transporter (SERT) protein, whose genes can have two allelic forms, namely long (L) and short (S), is suspected to be related to IPAH risk. Several studies have investigated the association between SERT's different allelic forms and IPAH but showed conflicting results. A meta-analysis of published studies was performed to allow a more reliable estimate of this association. METHODS Relevant databases were searched to identify eligible studies published from 2000 to 2013. Odds ratios (OR) and 95% confidence intervals (CI) were determined for the gene-disease association using fixed or random effects models. RESULTS A total of 6 studies with 451 IPAH subjects and 664 controls were included in this meta-analysis. A significant difference was found in the comparison between IPAH subjects and controls with LL vs. SS genotypes, and the pooled odds ratio (OR) with the fixed effects model was 1.446 (95% CI=1.036-2.018, p=0.030, I(2)=38.8%). However, no statistically significant differences were observed for LL vs. LS or LL vs. LS+SS. The pooled OR indicated no significant differences in IPAH risk between carriers of SERT L and S alleles (ORL VS. S=1.327, 95% CI=0.933-1.886, p=0.115). CONCLUSION This meta-analysis provides evidence suggesting an association between the SERT L/S polymorphism and IPAH. Individuals with the LL genotype have an obviously higher risk of developing IPAH than those with the SS genotype.
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Affiliation(s)
- Hang Zhang
- Affiliated Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Ave, Qiaokou district, Wuhan City, Hubei Province 430030, China.
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Austin ED, Loyd JE. Heritable forms of pulmonary arterial hypertension. Semin Respir Crit Care Med 2013; 34:568-80. [PMID: 24037626 DOI: 10.1055/s-0033-1355443] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Tremendous progress has been made in understanding the genetics of heritable pulmonary arterial hypertension (HPAH) since its description in the 1950s. Germline mutations in the gene coding bone morphogenetic receptor type 2 (BMPR2) are detectable in the majority of cases of HPAH, and in a small proportion of cases of idiopathic pulmonary arterial hypertension (IPAH). Recent advancements in gene sequencing methods have facilitated the discovery of additional genes with mutations among those with and without familial PAH (CAV1, KCNK3). HPAH is an autosomal dominant disease characterized by reduced penetrance, variable expressivity, and female predominance. These characteristics suggest that genetic and nongenetic factors modify disease expression, highlighting areas of active investigation. The reduced penetrance makes genetic counseling complex, as the majority of carriers of PAH-related mutations will never be diagnosed with the disease. This issue is increasingly important, as clinical testing for BMPR2 and other mutations is now available for the evaluation of patients and their at-risk kin. The possibilities to avoid mutation transmission, such as the rapidly advancing field of preimplantation genetic testing, highlight the need for all clinicians to understand the genetic features of PAH risk.
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Affiliation(s)
- Eric D Austin
- Division of Pulmonary, Allergy, and Immunology Medicine, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee
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Thomas M, Ciuclan L, Hussey MJ, Press NJ. Targeting the serotonin pathway for the treatment of pulmonary arterial hypertension. Pharmacol Ther 2013; 138:409-17. [PMID: 23416102 DOI: 10.1016/j.pharmthera.2013.02.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 01/07/2013] [Indexed: 01/22/2023]
Abstract
As we uncover the complex pathophysiology underlying idiopathic and familial pulmonary arterial hypertension, multiple disease associated pathways, cell types and processes reveal links to elements of the serotonin system. Beyond the original 'serotonin hypothesis' observed with anorexigens, and the latterly demonstrated association with vascular tone and pulmonary artery smooth muscle cell proliferation, recent studies suggest links to BMPR2, PDGF and RhoK pathways, as well as an impact upon more complex lesion formation and pathologic bone marrow progenitor mobilization. Clinical experience with antagonists targeting the various elements of the serotonin pathway has been unsatisfactory, yet perhaps this is less than surprising given our expanding knowledge around serotonin production and signaling biology, which indicate opportunities for novel therapeutic options.
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Affiliation(s)
- Matthew Thomas
- Respiratory Disease Area, Novartis Institutes for BioMedical Research, Wimblehurst Road, Horsham, West Sussex, RH12 5AB, United Kingdom.
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Cogan J, Austin E, Hedges L, Womack B, West J, Loyd J, Hamid R. Role of BMPR2 alternative splicing in heritable pulmonary arterial hypertension penetrance. Circulation 2012; 126:1907-16. [PMID: 22923426 DOI: 10.1161/circulationaha.112.106245] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Bone morphogenic protein receptor 2 (BMPR2) gene mutations are the most common cause of heritable pulmonary arterial hypertension. However, only 20% of mutation carriers get clinical disease. Here, we explored the hypothesis that this reduced penetrance is due in part to an alteration in BMPR2 alternative splicing. METHODS AND RESULTS Our data showed that BMPR2 has multiple alternative spliced variants. Two of these, isoform-A (full length) and isoform-B (missing exon 12), were expressed in all tissues analyzed. Analysis of cultured lymphocytes of 47 BMPR2 mutation-positive heritable pulmonary arterial hypertension patients and 35 BMPR2 mutation-positive unaffected carriers showed that patients had higher levels of isoform-B compared with isoform-A (B/A ratio) than carriers (P=0.002). Furthermore, compared with cells with a low B/A ratio, cells with a high B/A ratio had lower levels of unphosphorylated cofilin after BMP stimulation. Analysis of exon 12 sequences identified an exonic splice enhancer that binds serine arginine splicing factor 2 (SRSF2). Because SRSF2 promotes exon inclusion, reduced SRSF2 expression would mean that exon 12 would not be included in final BMPR2 mRNA (thus promoting increased isoform-B formation). Western blot analysis showed that SRSF2 expression was lower in cells from patients compared with cells from carriers and that siRNA-mediated knockdown of SRSF2 in pulmonary microvascular endothelial cells resulted in elevated levels of isoform-B compared with isoform-A, ie, an elevated B/A ratio. CONCLUSIONS Alterations in BMPR2 isoform ratios may provide an explanation of the reduced penetrance among BMPR2 mutation carriers. This ratio is controlled by an exonic splice enhancer in exon 12 and its associated splicing factor, SRSF2.
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Affiliation(s)
- Joy Cogan
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Abstract
Pulmonary arterial hypertension (PAH) is a rapidly progressive and fatal disease for which there is an ever-expanding body of genetic and related pathophysiological information on disease pathogenesis. The most common single culprit gene known is BMPR2, and animal models of the disease in several forms exist. There is a wealth of genetic data regarding modifiers of disease expression, penetrance, and severity. Despite the rapid accumulation of data in the last decade, a complete picture of the molecular pathogenesis of PAH leading to novel therapies is lacking. In this review, we attempt to summarize the current understanding of PAH from the genetic perspective. The most recent PAH demographics are discussed. Heritable PAH in the post-BMPR2 era is examined in detail as the most robust model of PAH genetics in both animal models and human pedigrees. Important downstream molecular pathways and modifiers of disease expression are reviewed in light of what is known about PAH pathogenesis. Current and emerging therapies are examined in light of genetic data. The role of genetic testing in PAH in the post-BMPR2 era is discussed. Finally, directions for future investigations that ideally will fulfill the promise of novel therapeutic or preventive strategies are discussed.
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Affiliation(s)
- Joshua P Fessel
- Department of Medicine, Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University, Nashville, Tennessee, US
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Pleym H, Greiff G, Mjorndal T, Stenseth R, Wahba A, Spigset O. Effect of serotonin reuptake inhibitors on pulmonary hemodynamics in humans. J Clin Med Res 2012; 3:230-8. [PMID: 22383910 PMCID: PMC3279484 DOI: 10.4021/jocmr654w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2011] [Indexed: 11/10/2022] Open
Abstract
Background Serotonin promotes pulmonary arterial vasoconstriction and pulmonary arterial smooth muscle cell proliferation, thereby having the potential to increase pulmonary arterial blood pressure. Although serotonin reuptake inhibitors (SRIs) might inhibit further deterioration in patients with manifest pulmonary arterial hypertension, they may induce pulmonary hypertension in healthy newborns after fetal exposure. As it is unclear whether treatment with SRIs affects pulmonary hemodynamics in adults without pulmonary hypertension, the aim of the present study was to investigate the effect of SRIs on pulmonary hemodynamics in such subjects. Methods Sixteen patients with stable angina pectoris scheduled for first time coronary artery bypass grafting were included in the study. Of these 8 were currently treated with an SRI (the SRI group) and 8 were not (the control group). Pulmonary arterial pressures were measured before induction of anesthesia by means of a pulmonary artery catheter. Serotonin transporter and 5-HT2A receptor gene polymorphisms and platelet 5-HT2A receptor expression were studied to elucidate their possible role as modifying factors. Results No patients in any of the groups had pulmonary arterial hypertension. Mean pulmonary artery pressure was 15.0 mmHg in the SRI group and 14.5 mmHg in the control group (P = 0.50; 95% confidence interval for the difference, -2.9 to +3.9 mmHg). Neither were there any significant differences between the groups for any of the other hemodynamic variables studied. The various gene polymorphisms and the extent of platelet 5-HT2A receptor expression did not influence the hemodynamic variables. Conclusions SRI treatment did not significantly influence pulmonary hemodynamics in patients without pulmonary hypertension. Keywords Serotonin; Selective serotonin reuptake inhibitors; Pulmonary hemodynamics; Pulmonary hypertension
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Affiliation(s)
- Hilde Pleym
- Department of Cardiothoracic Anesthesia and Intensive Care, St. Olav University Hospital, Trondheim, Norway
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Baloira A, Núñez M, Cifrian J, Vilariño C, Ojeda M, Valverde D. Polimorfismos en el gen de la proteína transportadora de serotonina (SERT) en pacientes con hipertensión arterial pulmonar. Arch Bronconeumol 2012; 48:77-80. [DOI: 10.1016/j.arbres.2011.10.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/17/2011] [Accepted: 10/19/2011] [Indexed: 10/14/2022]
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Zhong H, Haddjeri N, Sánchez C. Escitalopram, an antidepressant with an allosteric effect at the serotonin transporter--a review of current understanding of its mechanism of action. Psychopharmacology (Berl) 2012; 219:1-13. [PMID: 21901317 DOI: 10.1007/s00213-011-2463-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 08/19/2011] [Indexed: 02/08/2023]
Abstract
RATIONALE Escitalopram is a widely used antidepressant for the treatment of patients with major depression. It is the pure S-enantiomer of racemic citalopram. Several clinical trials and meta-analyses indicate that escitalopram is quantitatively more efficacious than many other antidepressants with a faster onset of action. OBJECTIVE This paper reviews current knowledge about the mechanism of action of escitalopram. RESULTS The primary target for escitalopram is the serotonin transporter (SERT), which is responsible for serotonin (or 5-hydroxytryptamine [5-HT]) reuptake at the terminals and cell bodies of serotonergic neurons. Escitalopram and selective serotonin reuptake inhibitors bind with high affinity to the 5-HT binding site (orthosteric site) on the transporter. This leads to antidepressant effects by increasing extracellular 5-HT levels which enhance 5-HT neurotransmission. SERT also has one or more allosteric sites, binding to which modulates activity at the orthosteric binding site but does not directly affect 5-HT reuptake by the transporter. In vitro studies have shown that through allosteric binding, escitalopram decreases its own dissociation rate from the orthosteric site on the SERT. R-citalopram, the nontherapeutic enantiomer in citalopram, is also an allosteric modulator of SERT but can inhibit the actions of escitalopram by interfering negatively with its binding. Both nonclinical studies and some clinical investigations have demonstrated the cellular, neurochemical, neuroadaptive, and neuroplastic changes induced by escitalopram with acute and chronic administration. CONCLUSIONS The findings from binding, neurochemical, and neurophysiological studies may provide a mechanistic rationale for the clinical difference observed with escitalopram compared to other antidepressant therapies.
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Affiliation(s)
- Huailing Zhong
- U-Pharm Laboratories LLC, 239 New Road, Suite A-107, Parsippany, NJ 07054, USA.
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Machado RD. The molecular genetics and cellular mechanisms underlying pulmonary arterial hypertension. SCIENTIFICA 2012; 2012:106576. [PMID: 24278664 PMCID: PMC3820608 DOI: 10.6064/2012/106576] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 11/19/2012] [Indexed: 05/14/2023]
Abstract
Pulmonary arterial hypertension (PAH) is an incurable disorder clinically characterised by a sustained elevation of mean arterial pressure in the absence of systemic involvement. As the adult circulation is a low pressure, low resistance system, PAH represents a reversal to a foetal state. The small pulmonary arteries of patients exhibit luminal occlusion resultant from the uncontrolled growth of endothelial and smooth muscle cells. This vascular remodelling is comprised of hallmark defects, most notably the plexiform lesion. PAH may be familial in nature but the majority of patients present with spontaneous disease or PAH associated with other complications. In this paper, the molecular genetic basis of the disorder is discussed in detail ranging from the original identification of the major genetic contributant to PAH and moving on to current next-generation technologies that have led to the rapid identification of additional genetic risk factors. The impact of identified mutations on the cell is examined, particularly, the determination of pathways disrupted in disease and critical to pulmonary vascular maintenance. Finally, the application of research in this area to the design and development of novel treatment options for patients is addressed along with the future directions PAH research is progressing towards.
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Affiliation(s)
- Rajiv D. Machado
- School of Life Sciences, Faculty of Science, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, UK
- *Rajiv D. Machado:
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Haddad F, Kudelko K, Mercier O, Vrtovec B, Zamanian RT, de Jesus Perez V. Pulmonary hypertension associated with left heart disease: characteristics, emerging concepts, and treatment strategies. Prog Cardiovasc Dis 2011; 54:154-67. [PMID: 21875514 DOI: 10.1016/j.pcad.2011.06.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Left heart disease (LHD) represents the most common causes of pulmonary hypertension (PH). Whether caused by systolic or diastolic dysfunction or valvular heart disease, a hallmark of PH associated with LHD is elevated left atrial pressure. In all cases, the increase in left atrial pressure causes a passive increase in pulmonary pressure. In some patients, a superimposed active component caused by pulmonary arterial vasoconstriction and vascular remodeling may lead to a further increase in pulmonary arterial pressure. When present, PH is associated with a worse prognosis in patients with LHD. In addition to local abnormalities in nitric oxide and endothelin production, gene modifiers such as serotonin polymorphisms may be associated with the pathogenesis of PH in LHD. Optimizing heart failure regimens and corrective valve surgery represent the cornerstone of the treatment of PH in LHD. Recent studies suggest that sildenafil, a phosphodiesterase-5 inhibitor, is a promising agent in the treatment of PH in LHD. Unloading the left ventricle with circulatory support may also reverse severe PH in patients with end-stage heart failure allowing candidacy to heart transplantation.
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Affiliation(s)
- Francois Haddad
- Division of Cardiovascular Medicine, Stanford School of Medicine, CA 94305, USA.
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Kristensen AS, Andersen J, Jørgensen TN, Sørensen L, Eriksen J, Loland CJ, Strømgaard K, Gether U. SLC6 neurotransmitter transporters: structure, function, and regulation. Pharmacol Rev 2011; 63:585-640. [PMID: 21752877 DOI: 10.1124/pr.108.000869] [Citation(s) in RCA: 591] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The neurotransmitter transporters (NTTs) belonging to the solute carrier 6 (SLC6) gene family (also referred to as the neurotransmitter-sodium-symporter family or Na(+)/Cl(-)-dependent transporters) comprise a group of nine sodium- and chloride-dependent plasma membrane transporters for the monoamine neurotransmitters serotonin (5-hydroxytryptamine), dopamine, and norepinephrine, and the amino acid neurotransmitters GABA and glycine. The SLC6 NTTs are widely expressed in the mammalian brain and play an essential role in regulating neurotransmitter signaling and homeostasis by mediating uptake of released neurotransmitters from the extracellular space into neurons and glial cells. The transporters are targets for a wide range of therapeutic drugs used in treatment of psychiatric diseases, including major depression, anxiety disorders, attention deficit hyperactivity disorder and epilepsy. Furthermore, psychostimulants such as cocaine and amphetamines have the SLC6 NTTs as primary targets. Beginning with the determination of a high-resolution structure of a prokaryotic homolog of the mammalian SLC6 transporters in 2005, the understanding of the molecular structure, function, and pharmacology of these proteins has advanced rapidly. Furthermore, intensive efforts have been directed toward understanding the molecular and cellular mechanisms involved in regulation of the activity of this important class of transporters, leading to new methodological developments and important insights. This review provides an update of these advances and their implications for the current understanding of the SLC6 NTTs.
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Affiliation(s)
- Anders S Kristensen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Baliga RS, MacAllister RJ, Hobbs AJ. New perspectives for the treatment of pulmonary hypertension. Br J Pharmacol 2011; 163:125-40. [PMID: 21175577 PMCID: PMC3085874 DOI: 10.1111/j.1476-5381.2010.01164.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 11/12/2010] [Accepted: 11/16/2010] [Indexed: 11/30/2022] Open
Abstract
Pulmonary hypertension (PH) is a debilitating disease with a poor prognosis. Therapeutic options remain limited despite the introduction of prostacyclin analogues, endothelin receptor antagonists and phosphodiesterase 5 inhibitors within the last 15 years; these interventions address predominantly the endothelial and vascular dysfunctionS associated with the condition, but simply delay progression of the disease rather than offer a cure. In an attempt to improve efficacy, emerging approaches have focused on targeting the pro-proliferative phenotype that underpins the pulmonary vascular remodelling in the lung and contributes to the impaired circulation and right heart failure. Many novel targets have been investigated and validated in animal models of PH, including modulation of guanylate cyclases, phosphodiesterases, tyrosine kinases, Rho kinase, bone morphogenetic proteins signalling, 5-HT, peroxisome proliferator activator receptors and ion channels. In addition, there is hope that combinations of such treatments, harnessing and optimizing vasodilator and anti-proliferative properties, will provide a further, possibly synergistic, increase in efficacy; therapies directed at the right heart may also offer an additional benefit. This overview highlights current therapeutic options, promising new therapies, and provides the rationale for a combination approach to treat the disease.
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White K, Dempsie Y, Nilsen M, Wright AF, Loughlin L, MacLean MR. The serotonin transporter, gender, and 17β oestradiol in the development of pulmonary arterial hypertension. Cardiovasc Res 2010; 90:373-82. [PMID: 21177701 DOI: 10.1093/cvr/cvq408] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Idiopathic and familial forms of pulmonary arterial hypertension (PAH) predominantly affect females through an unknown mechanism. Activity of the serotonin transporter (SERT) may modulate the development of PAH, and mice overexpressing SERT (SERT+ mice) develop PAH and severe hypoxia-induced PAH. In the central nervous system, oestrogens influence activity of the serotonin system. Therefore, we examined the influence of gender on the development of PAH in SERT+ mice and how this is modulated by female hormones. METHODS AND RESULTS PAH was assessed via measurement of right ventricular systolic pressure (RVSP), pulmonary vascular remodelling (PVR), and right ventricular hypertrophy. Male SERT+ mice did not develop PAH. Female SERT+ mice demonstrated increased RVSP and PVR and this was abolished by ovariectomy. Following exposure to hypoxia, SERT+ mice exhibited severe PAH and this was also attenuated by ovariectomy. Chronic administration of 17β oestradiol re-established the PAH phenotype in ovariectomized, normoxic, and hypoxic SERT+ mice. 17β oestradiol also up-regulated tryptophan hydroxylase-1 (TPH1), 5-hydroytryptamine(1B) (5-HT(1B)) receptor, and SERT expression in human pulmonary arterial smooth muscle cells (hPASMCs). 17β oestradiol stimulated hPASMC proliferation and this was inhibited by both the TPH inhibitor para-chlorophenylalanine and the 5-HT(1B) receptor antagonist SB224289. CONCLUSION 17β oestradiol is critical to the development of PAH and severe hypoxia-induced PAH in female SERT+ mice. In hPASMCs, 17β oestradiol-induced proliferation is dependant on de novo serotonin synthesis and stimulation of the 5-HT(1B) receptor. These interactions between the serotonin system and 17β oestradiol may contribute to the increased risk of PAH associated with female gender.
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Affiliation(s)
- Kevin White
- Research Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, West Medical Building, University of Glasgow G12 8QQ, UK
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Archer SL, Weir EK, Wilkins MR. Basic science of pulmonary arterial hypertension for clinicians: new concepts and experimental therapies. Circulation 2010; 121:2045-66. [PMID: 20458021 DOI: 10.1161/circulationaha.108.847707] [Citation(s) in RCA: 373] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Tissot C, Beghetti M. Advances in therapies for pediatric pulmonary arterial hypertension. Expert Rev Respir Med 2010; 3:265-82. [PMID: 20477321 DOI: 10.1586/ers.09.16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by progressive obliteration of the pulmonary vasculature, leading to right heart failure and death if left untreated. Prior to the current treatment era, pulmonary hypertension carried a poor prognosis with a high mortality rate, but its prognosis has changed over the past decades in relation to new therapeutic agents. Nevertheless, pulmonary hypertension continues to be a serious condition, which is extremely challenging to manage. The data in children are often limited owing to the small number of patients, and extrapolation from adults to children is not straightforward. While none of these new therapeutic agents have been specifically approved for children, there is evidence that each can appropriately benefit the PAH child. We review the current understanding of pediatric pulmonary hypertension, classification, diagnostic evaluation and available treatment. A description of targeted pharmacological therapy and new treatments in children is outlined.
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Affiliation(s)
- Cecile Tissot
- The Children's University Hospital of Geneva, Pediatric Cardiology Unit, 6 rue Willy Donze, 1211 Geneva 14, Switzerland.
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Wipff J, Bonnet P, Ruiz B, Dieude P, Avouac J, Tiev K, Hachulla E, Cracowski JL, Diot E, Sibilia J, Mouthon L, Meyer O, Kahan A, Boileau C, Allanore Y. Association study of serotonin transporter gene (SLC6A4) in systemic sclerosis in European Caucasian populations. J Rheumatol 2010; 37:1164-7. [PMID: 20395645 DOI: 10.3899/jrheum.091156] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Serotonin is a key contributing factor in pulmonary arterial hypertension (PAH) by inducing pulmonary arterial smooth muscle cell (PA-SMC) proliferation. This relates specifically to the internalization process in PA-SMC of the serotonin transporter (SLC6A4 or 5-HTT). A long (L)/short (S) (44 base pair insertion) functional polymorphism within the promoter of the transporter SLC6A4 gene has been reported to be associated with familial and idiopathic PAH. Our objective was to determine whether polymorphisms of SLC6A4 confer susceptibility to SSc and its vascular phenotype. METHODS Three Tag single-nucleotide polymorphisms (SNP) (rs2066713, rs1042173, rs6354) chosen using Hapmap and linkage disequilibrium data were genotyped in a total cohort of 667 SSc patients (56 with PAH, 207 with digital ulcerations) and 447 controls. All individuals were of French Caucasian origin. L/S polymorphism genotyping was determined by polymerase chain reaction in a random subgroup of 364 SSc patients (34 with PAH, 138 with digital ulcerations) and 218 controls. RESULTS Three polymorphisms (L/S, rs2066713, rs1042173) were in Hardy-Weinberg equilibrium in the control population, but rs6354 deviated. Allelic and genotypic frequencies for these 3 polymorphisms were similar in SSc patients and controls. Subphenotype analyses of subsets with PAH and digital ulceration did not detect any difference between SSc patients compared to controls. CONCLUSION These results from a large cohort of European Caucasian SSc patients do not support the implication of SLC6A4 in the pathogenesis of SSc and its vascular subphenotypes. However, serotonin pathways remain good candidates to contribute to the vasculopathy of SSc.
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Affiliation(s)
- Julien Wipff
- Service de Rhumatologie A, Hôpital Cochin, 27 rue du Faubourg St Jacques, 75014 Paris, France.
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Thomas M. Pharmacological targets for pulmonary vascular disease: vasodilation versus anti-remodelling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 661:475-90. [PMID: 20204750 DOI: 10.1007/978-1-60761-500-2_31] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Two gross mechanisms of pathology are central to pulmonary arterial hypertension - increased pulmonary vascular tone and remodelling of the pulmonary arteries. These pathologies can be caused by a variety of aberrant processes, and combine to cause an increase in pulmonary vascular resistance and consequent right ventricular hypertrophy, eventually leading to dysfunction and death. Current therapeutic strategies have focused on altering the vasoconstrictive elements of the disease. Whilst improvements in life expectancy have been observed, current therapies have not managed to halt or reverse progression of the disease. Here we discuss said unmet medical need and postulate as to the impact on disease anti-remodelling therapy might provide. The mechanisms of remodelling in pulmonary arterial hypertension are reviewed, and leading examples of potential targets within such mechanisms are discussed.
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Affiliation(s)
- Matthew Thomas
- Novartis Institutes for Biomedical Research, Respiratory Disease Area, Horsham, UK.
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The Serotonin Hypothesis of Pulmonary Hypertension Revisited. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 661:309-22. [DOI: 10.1007/978-1-60761-500-2_20] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Ivy DD, Feinstein JA, Humpl T, Rosenzweig EB. Non-congenital heart disease associated pediatric pulmonary arterial hypertension. PROGRESS IN PEDIATRIC CARDIOLOGY 2009; 27:13-23. [PMID: 21852894 DOI: 10.1016/j.ppedcard.2009.09.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recognition of causes of pulmonary hypertension other than congenital heart disease is increasing in children. Diagnosis and treatment of any underlying cause of pulmonary hypertension is crucial for optimal management of pulmonary hypertension. This article discusses the available knowledge regarding several disorders associated with pulmonary hypertension in children: idiopathic pulmonary arterial hypertension (IPAH), pulmonary capillary hemangiomatosis, pulmonary veno-occlusive disease, hemoglobinopathies, hepatopulmonary syndrome, portopulmonary hypertension and HIV. Three classes of drugs have been extensively studied for the treatment of IPAH in adults: prostanoids (epoprostenol, treprostinil, iloprost, beraprost), endothelin receptor antagonists (bosentan, sitaxsentan, ambrisentan), and phosphodiesterase inhibitors (Sildenafil, tadalafil). These medications have been used in treatment of children with pulmonary arterial hypertension, although randomized clinical trial data is lacking. As pulmonary vasodilator therapy in certain diseases may be associated with adverse outcomes, further study of these medications is needed before widespread use is encouraged.
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Affiliation(s)
- D D Ivy
- University of Colorado Denver School of Medicine and The Children's Hospital, United States
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Cao H, Gu H, Qiu W, Zuo W, Zheng L, Wang Z, Hu Z, Chen Y. Association Study of Serotonin Transporter Gene Polymorphisms and Ventricular Septal Defects RelatedPossiblePulmonary Arterial Hypertension in Chinese Population. Clin Exp Hypertens 2009; 31:605-14. [DOI: 10.3109/10641960902993061] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Morecroft I, Pang L, Baranowska M, Nilsen M, Loughlin L, Dempsie Y, Millet C, MacLean MR. In vivo effects of a combined 5-HT1B receptor/SERT antagonist in experimental pulmonary hypertension. Cardiovasc Res 2009; 85:593-603. [DOI: 10.1093/cvr/cvp306] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Austin ED, Loyd JE, Phillips JA. Genetics of pulmonary arterial hypertension. Semin Respir Crit Care Med 2009; 30:386-98. [PMID: 19634078 DOI: 10.1055/s-0029-1233308] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Tremendous progress has been made in understanding the genetics of hereditable pulmonary arterial hypertension (HPAH) since its description in the 1950s. Germline mutations in the gene coding bone morphogenetic receptor type 2 ( BMPR2) are detectable in the majority of cases of HPAH, and in a small proportion of cases of idiopathic pulmonary arterial hypertension (IPAH). HPAH is an autosomal dominant disease characterized by reduced penetrance, variable expressivity, female predominance, and genetic anticipation. These characteristics suggest that endogenous and exogenous factors modify disease expression and areas of emphasis for future investigation. The variable clinical expression makes genetic counseling complex because the majority of carriers of a BMPR2 mutation will not be diagnosed with the disease. This issue will become increasingly important, as clinical testing for BMPR2 mutations is now available for the evaluation of patients and family members with HPAH and IPAH.
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Affiliation(s)
- Eric D Austin
- Department of Pediatrics, Division of Pulmonary, Allergy, and Immunology Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2578, USA
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Machado RD, Eickelberg O, Elliott CG, Geraci MW, Hanaoka M, Loyd JE, Newman JH, Phillips JA, Soubrier F, Trembath RC, Chung WK. Genetics and genomics of pulmonary arterial hypertension. J Am Coll Cardiol 2009; 54:S32-S42. [PMID: 19555857 DOI: 10.1016/j.jacc.2009.04.015] [Citation(s) in RCA: 255] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 04/15/2009] [Indexed: 11/17/2022]
Abstract
Pulmonary arterial hypertension (PAH) is a rare disorder that may be hereditable (HPAH), idiopathic (IPAH), or associated with either drug-toxin exposures or other medical conditions. Familial cases have long been recognized and are usually due to mutations in the bone morphogenetic protein receptor type 2 gene (BMPR2), or, much less commonly, 2 other members of the transforming growth factor-beta superfamily, activin-like kinase-type 1 (ALK1) and endoglin (ENG), which are associated with hereditary hemorrhagic telangiectasia. In addition, approximately 20% of patients with IPAH carry mutations in BMPR2. We provide a summary of BMPR2 mutations associated with HPAH, most of which are unique to each family and are presumed to result in loss of function. We review the finding of missense variants and variants of unknown significance in BMPR2 in IPAH/HPAH, fenfluramine exposure, and PAH associated with congenital heart disease. Clinical testing for BMPR2 mutations is available and may be offered to HPAH and IPAH patients but should be preceded by genetic counseling, since lifetime penetrance is only 10% to 20%, and there are currently no known effective preventative measures. Identification of a familial mutation can be valuable in reproductive planning and identifying family members who are not mutation carriers and thus will not require lifelong surveillance. With advances in genomic technology and with international collaborative efforts, genome-wide association studies will be conducted to identify additional genes for HPAH, genetic modifiers for BMPR2 penetrance and genetic susceptibility to IPAH. In addition, collaborative studies of BMPR2 mutation carriers should enable identification of environmental modifiers, biomarkers for disease development and progression, and surrogate markers for efficacy end points in clinical drug development, thereby providing an invaluable resource for trials of PAH prevention.
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Affiliation(s)
- Rajiv D Machado
- Department of Medical and Molecular Genetics, King's College London School of Medicine, Guy's Hospital, London, United Kingdom.
| | - Oliver Eickelberg
- Comprehensive Pneumology Center, Ludwig-Maximilians-Universität, Asklepios Klinik Gauting und Helmholtz Zentrum München, and Institute of Lung Biology and Disease (iLBD), Helmholtz Zentrum München, Munich, Germany
| | - C Gregory Elliott
- Departments of Medicine, Intermountain Medical Center and the University of Utah School of Medicine, Salt Lake City, Utah
| | - Mark W Geraci
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, Colorado
| | - Masayuki Hanaoka
- First Department of Medicine, Shinshu University School of Medicine, Matsumoto, Japan
| | - James E Loyd
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - John H Newman
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - John A Phillips
- Department of Pediatrics and Division of Medical Genetics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Florent Soubrier
- Faculté de Medicine, Université Paris 6, Hôpital Pitié-Salpêtrière, Paris, France
| | - Richard C Trembath
- Department of Medical and Molecular Genetics, King's College London School of Medicine, Guy's Hospital, London, United Kingdom
| | - Wendy K Chung
- Departments of Pediatrics and Medicine, Columbia University College of Physicians & Surgeons, New York, New York
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Shah SJ, Gomberg-Maitland M, Thenappan T, Rich S. Selective serotonin reuptake inhibitors and the incidence and outcome of pulmonary hypertension. Chest 2009; 136:694-700. [PMID: 19349384 DOI: 10.1378/chest.08-2823] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Selective serotonin reuptake inhibitors (SSRIs) prevent the development of and reverse pulmonary hypertension (PH) in animal models. We sought to determine whether SSRIs are associated with a decreased incidence of PH in at-risk patients and whether SSRIs are associated with decreased mortality in patients with established PH. METHODS In a case-control study of patients enrolled in the Surveillance of Pulmonary Hypertension in America (SOPHIA) registry, we tested whether patients without PH (no-PH group; n = 155) were more likely to be receiving SSRIs when compared to those with confirmed PH (n = 1,180). In a separate cohort study of adults with documented PH in the referral-based Pulmonary Hypertension Connection (PHC) registry (n = 542), we classified patients into categories by SSRI use, and we examined whether SSRI use was associated with decreased mortality. RESULTS In SOPHIA, the confirmed PH group was less likely to be receiving SSRIs compared with the no-PH group (univariate odds ratio [OR], 0.56 [95% confidence interval (CI), 0.39 to 0.82]; p = 0.003; multivariate OR, 0.71l [95% CI, 0.48 to 1.06]; p = 0.09). In the PHC, 69 of 542 patients (13%) were receiving SSRIs at the time of referral. During a mean (+/- SD) follow-up period of 4.0 +/- 3.1 years, 12% of patients receiving SSRIs vs 23% of patients not receiving SSRIs died (hazard ratio [HR], 0.35; 95% CI, 0.14 to 0.87; p = 0.023). The association between SSRI use and decreased mortality persisted after adjusting for age, gender, etiology of PH, and obesity (HR, 0.35; 95% CI, 0.14 to 0.88; p = 0.026). CONCLUSIONS SSRIs appear to be associated with a decreased development of PH and a decreased mortality in PH. These findings provide a rationale for clinical trials of SSRIs in PH.
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Affiliation(s)
- Sanjiv J Shah
- Division of Cardiology, Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
| | | | - Thenappan Thenappan
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, IL
| | - Stuart Rich
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, IL.
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Roberts KE, Fallon MB, Krowka MJ, Brown RS, Trotter JF, Peter I, Tighiouart H, Knowles JA, Rabinowitz D, Benza RL, Badesch DB, Taichman DB, Horn EM, Zacks S, Kaplowitz N, Kawut SM. Genetic risk factors for portopulmonary hypertension in patients with advanced liver disease. Am J Respir Crit Care Med 2009; 179:835-42. [PMID: 19218192 DOI: 10.1164/rccm.200809-1472oc] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Portopulmonary hypertension (PPHTN) occurs in 6% of liver transplant candidates. The pathogenesis of this complication of portal hypertension is poorly understood. OBJECTIVES To identify genetic risk factors for PPHTN in patients with advanced liver disease. METHODS We performed a multicenter case-control study of patients with portal hypertension. Cases had a mean pulmonary artery pressure >25 mm Hg, pulmonary vascular resistance >240 dynes.s(-1).cm(-5), and pulmonary capillary wedge pressure < or =15 mm Hg. Controls had a right ventricular systolic pressure < 40 mm Hg (if estimated) and normal right-sided cardiac morphology by transthoracic echocardiography. We genotyped 1,079 common single nucleotide polymorphisms (SNPs) in 93 candidate genes in each patient. MEASUREMENTS AND MAIN RESULTS The study sample included 31 cases and 104 controls. Twenty-nine SNPs in 15 candidate genes were associated with the risk of PPHTN (P < 0.05). Multiple SNPs in the genes coding for estrogen receptor 1, aromatase, phosphodiesterase 5, angiopoietin 1, and calcium binding protein A4 were associated with the risk of PPHTN. The biological relevance of one of the aromatase SNPs was supported by an association with plasma estradiol levels. CONCLUSIONS Genetic variation in estrogen signaling and cell growth regulators is associated with the risk of PPHTN. These biologic pathways may elucidate the mechanism for the development of PPHTN in certain patients with severe liver disease.
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Affiliation(s)
- Kari E Roberts
- Department of Medicine, Tufts Medical Center, Boston, MA 02111, USA.
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Yildiz P. Molecular mechanisms of pulmonary hypertension. Clin Chim Acta 2009; 403:9-16. [PMID: 19361468 DOI: 10.1016/j.cca.2009.01.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Revised: 01/18/2009] [Accepted: 01/23/2009] [Indexed: 12/11/2022]
Abstract
The pathogenesis of pulmonary arterial hypertension (PAH) is complex, involving multiple modulating genes and environmental factors. Multifactorial impairment of the physiologic balance can lead to vasoconstriction, vascular smooth muscle cell and endothelial cell proliferation/fibrosis, inflammation, remodeling and in-situ thrombosis. These are the likely mechanisms that lead to narrowing of the vessel followed by progressive increase in pulmonary vascular resistance and the clinical manifestations of pulmonary hypertension. Subsequently, major goal of the therapy is to avoid acute pulmonary vasoconstriction, halt the progression of vascular remodeling, and reverse the early vascular remodeling if possible. Recently published data addressing certain molecular mechanisms for pathogenesis of PAH have led to the successful therapeutic interventions. This review will focus on the common and critical molecular pathways including genetic basis of the development of PAH that on the whole may be new targets for therapeutic interventions.
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Affiliation(s)
- Pinar Yildiz
- Department of Pulmonology, Yedikule Chest Disease and Surgery Training and Research Hospital, Zeytinburnu Istanbul, Turkey.
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Roberts KE, Fallon MB, Krowka MJ, Benza RL, Knowles JA, Badesch DB, Brown RS, Taichman DB, Trotter J, Zacks S, Horn EM, Kawut SM. Serotonin transporter polymorphisms in patients with portopulmonary hypertension. Chest 2009; 135:1470-1475. [PMID: 19141529 DOI: 10.1378/chest.08-1909] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The long allele of a functional promoter polymorphism in the serotonin transporter (SERT) is associated with an increased risk of some forms of pulmonary arterial hypertension. We hypothesized that the long allele or other polymorphisms in SERT would be associated with an increased risk of portopulmonary hypertension (PPHTN) in patients with advanced liver disease. METHODS We performed a multicenter case-control study. Subjects undergoing liver transplant evaluation at seven centers were prospectively screened for the presence of PPHTN using transthoracic echocardiography. PPHTN was confirmed by right heart catheterization using standard criteria. RESULTS The study sample included 30 case patients with PPHTN and 109 control subjects with advanced liver disease. There was no significant association between the long allele and case status in an adjusted additive model (odds ratio, 0.63; 95% confidence interval, 0.33 to 1.21; p = 0.17). If anything, LL genotype tended to be associated with a lower risk of PPHTN. There were no associations between other SERT polymorphisms and PPHTN. CONCLUSIONS SERT polymorphisms are not associated with the risk of PPHTN in patients with advanced liver disease. Other clinical or genetic risk factors may play a role in this complication of portal hypertension.
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Affiliation(s)
- Kari E Roberts
- Department of Medicine, Tufts Medical Center, Boston, MA
| | | | | | - Raymond L Benza
- Department of Medicine, University of Alabama, Birmingham, AL
| | - James A Knowles
- Department of Psychiatry, University of Southern California, Los Angeles, CA
| | | | - Robert S Brown
- the Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY
| | - Darren B Taichman
- Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - James Trotter
- Department of Medicine, University of Colorado, Denver, CO
| | - Steven Zacks
- Department of Medicine, University of North Carolina, Chapel Hill, NC
| | - Evelyn M Horn
- the Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY
| | - Steven M Kawut
- Department of Medicine, University of Pennsylvania, Philadelphia, PA.
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Gene expression in BMPR2 mutation carriers with and without evidence of pulmonary arterial hypertension suggests pathways relevant to disease penetrance. BMC Med Genomics 2008; 1:45. [PMID: 18823550 PMCID: PMC2561034 DOI: 10.1186/1755-8794-1-45] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Accepted: 09/29/2008] [Indexed: 12/22/2022] Open
Abstract
Background While BMPR2 mutation strongly predisposes to pulmonary arterial hypertension (PAH), only 20% of mutation carriers develop clinical disease. This finding suggests that modifier genes contribute to FPAH clinical expression. Since modifiers are likely to be common alleles, this problem is not tractable by traditional genetic approaches. Furthermore, examination of gene expression is complicated by confounding effects attributable to drugs and the disease process itself. Methods To resolve these problems, B-cells were isolated, EBV-immortalized, and cultured from familial PAH patients with BMPR2 mutations, mutation positive but disease-free family members, and family members without mutation. This allows examination of differences in gene expression without drug or disease-related effects. These differences were assayed by Affymetrix array, with follow-up by quantitative RT-PCR and additional statistical analyses. Results By gene array, we found consistent alterations in multiple pathways with known relationship to PAH, including actin organization, immune function, calcium balance, growth, and apoptosis. Selected genes were verified by quantitative RT-PCR using a larger sample set. One of these, CYP1B1, had tenfold lower expression than control groups in female but not male PAH patients. Analysis of overrepresented gene ontology groups suggests that risk of disease correlates with alterations in pathways more strongly than with any specific gene within those pathways. Conclusion Disease status in BMPR2 mutation carriers was correlated with alterations in proliferation, GTP signaling, and stress response pathway expression. The estrogen metabolizing gene CYP1B1 is a strong candidate as a modifier gene in female PAH patients.
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Mair KM, MacLean MR, Morecroft I, Dempsie Y, Palmer TM. Novel interactions between the 5-HT transporter, 5-HT1B receptors and Rho kinase in vivo and in pulmonary fibroblasts. Br J Pharmacol 2008; 155:606-16. [PMID: 18695640 DOI: 10.1038/bjp.2008.310] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE While the 5-HT and Rho-kinase (ROCK) pathways have been implicated in the development of pulmonary arterial hypertension (PAH), the nature of any interactions between them remain unclear. This study investigated a role for ROCK in 5-HT-regulated proliferative responses in lung fibroblasts in vivo and in vitro. EXPERIMENTAL APPROACH PAH was examined in mice over-expressing human 5-HT transporters (SERT+), from which pulmonary artery fibroblasts (PFs) were isolated to assess ROCK expression. In vitro analysis of 5-HT signalling employed CCL39 hamster lung fibroblasts. KEY RESULTS ROCK inhibition ablated increased pulmonary remodelling and hypertension observed in SERT+ mice, and ROCK1/2 protein levels were elevated in SERT+ PFs. ROCK inhibition also reduced 5-HT-stimulated proliferation by suppressing MEK-stimulated ERK phosphorylation. While optimal 5-HT-stimulated proliferation required 5-HT(1B) and 5-HT(2A) receptors and SERT, receptor sensitivity to Y27632 was restricted to the 5-HT(1B) receptor. Also, while hypoxia-induced pulmonary vascular remodelling and hypertension were sensitive to Y27632 in WT and SERT+ animals, the proportions sensitive to ROCK inhibition were increased by SERT over-expression. CONCLUSIONS AND IMPLICATIONS SERT over-expression increased ROCK-dependent pulmonary remodelling in normoxia and hypoxia and SERT over-expression was associated with elevated ROCK1/2 levels. ROCK also potentiated 5-HT(1B) receptor-stimulated ERK activation and proliferation in vitro by facilitating MEK-ERK interaction.
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Affiliation(s)
- K M Mair
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, University of Glasgow, Glasgow, Scotland, UK
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Synergistic heterozygosity for TGFbeta1 SNPs and BMPR2 mutations modulates the age at diagnosis and penetrance of familial pulmonary arterial hypertension. Genet Med 2008; 10:359-65. [PMID: 18496036 DOI: 10.1097/gim.0b013e318172dcdf] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE We hypothesized that functional TGFbeta1 SNPs increase TGFbeta/BMP signaling imbalance in BMPR2 mutation heterozygotes to accelerate the age at diagnosis, increase the penetrance and SMAD2 expression in familial pulmonary arterial hypertension. METHODS Single nucleotide polymorphism genotypes of BMPR2 mutation heterozygotes, age at diagnosis, and penetrance of familial pulmonary arterial hypertension were compared and SMAD2 expression was studied in lung sections. RESULTS BMPR2 mutation heterozygotes with least active -509 or codon 10 TGFbeta1 SNPs had later mean age at diagnosis of familial pulmonary arterial hypertension (39.5 and 43.2 years) than those with more active genotypes (31.6 and 33.1 years, P = 0.03 and 0.02, respectively). Kaplan-Meier analysis also showed that those with the less active single nucleotide polymorphisms had later age at diagnosis. BMPR2 mutation heterozygotes with nonsense-mediated decay resistant BMPR2 mutations and the least, intermediate and most active -509 TGFbeta1 SNP genotypes had penetrances of 33, 72, and 80%, respectively (P = 0.003), whereas those with 0-1, 2, or 3-4 active single nucleotide polymorphism alleles had penetrances of 33, 72, and 75% (P = 0.005). The relative expression of TGFbeta1 dependent SMAD2 was increased in lung sections of those with familial pulmonary arterial hypertension compared with controls. CONCLUSIONS The TGFbeta1 SNPs studied modulate age at diagnosis and penetrance of familial pulmonary arterial hypertension in BMPR2 mutation heterozygotes, likely by affecting TGFbeta/BMP signaling imbalance. This modulation is an example of Synergistic Heterozygosity.
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Dempsie Y, MacLean MR. Pulmonary hypertension: therapeutic targets within the serotonin system. Br J Pharmacol 2008; 155:455-62. [PMID: 18536742 DOI: 10.1038/bjp.2008.241] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Pulmonary arterial hypertension (PAH) is characterized by a sustained and progressive elevation in pulmonary arterial pressure and pulmonary vascular remodelling leading to right heart failure and death. Prognosis is poor and novel therapeutic approaches are needed. The serotonin hypothesis of PAH originated in the 1960s after an outbreak of the disease was reported among patients taking the anorexigenic drugs aminorex and fenfluramine. These are indirect serotonergic agonists and serotonin transporter substrates. Since then many advances have been made in our understanding of the role of serotonin in the pathobiology of PAH. The rate-limiting enzyme in the synthesis of serotonin is tryptophan hydroxylase (Tph). Serotonin is synthesized, through Tph1, in the endothelial cells of the pulmonary artery and can then act on underlying pulmonary arterial smooth muscle cells and pulmonary arterial fibroblasts in a paracrine fashion causing constriction and remodelling. These effects of serotonin can be mediated through both the serotonin transporter and serotonin receptors. This review will discuss our current understanding of 'the serotonin hypothesis' of PAH and highlight possible therapeutic targets within the serotonin system.
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Affiliation(s)
- Y Dempsie
- Division of Neuroscience and Biomedical Systems, Institute of Biomedical Sciences, University of Glasgow, Scotland, UK.
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Converging Evidence in Support of the Serotonin Hypothesis of Dexfenfluramine-Induced Pulmonary Hypertension With Novel Transgenic Mice. Circulation 2008; 117:2928-37. [DOI: 10.1161/circulationaha.108.767558] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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