Familial Pulmonary Arterial Hypertension Research Articles

StratosPHere 2: study protocol for a response-adaptive randomised placebo-controlled phase II trial to evaluate hydroxychloroquine and phenylbutyrate in pulmonary arterial hypertension caused by mutations in BMPR2

BackgroundPulmonary arterial hypertension is a life-threatening progressive disorder characterised by high blood pressure (hypertension) in the arteries of the lungs (pulmonary artery). Although treatable, there is no known cure for this rare disorder, and its exact cause is unknown. Mutations in the bone morphogenetic protein receptor type-2 (BMPR2) are the most common genetic cause of familial pulmonary arterial hypertension. This study represents the first-ever trial of treatments aimed at directly rescuing the BMPR2 pathway, repurposing two drugs that have shown promise at restoring levels of BMPR2 signalling: hydroxychloroquine and phenylbutyrate.MethodsThis three-armed phase II precision medicine study will investigate BMPR2 target engagement and explore the efficacy of two repurposed therapies in pulmonary arterial hypertension patients with BMPR2 mutations. Patients will be stratified based on two BMPR2 mutation classes: missense and haploinsufficient mutations. Eligible subjects will be randomised to one of the three arms (two active therapy arms and a placebo arm, all plus standard of care) following a Bayesian response-adaptive design implemented independently in each stratum and updated in response to a novel panel of primary biomarkers designed to assess biological modification of the disease.DiscussionThe results of this trial will provide the first randomised evidence of the efficacy of these therapies to rescue BMPR2 function and will efficiently explore the potential for a differential response of these therapies per mutation class to address causes rather than consequences of this rare disease.Trial registrationThe study has been registered with ISRCTN (ISRCTN10304915, 22/09/2023).

Effects of Modulating BMP9, BMPR2, and AQP1 on BMP Signaling in Human Pulmonary Microvascular Endothelial Cells.

Pulmonary arterial hypertension (PAH) is a chronic disease characterized by a progressive increase in mean pulmonary arterial pressure. Mutations in the BMPR2 and AQP1 genes have been described in familial PAH. The bone morphogenetic proteins BMP9 and BMP10 bind with high affinity to BMPR2. Administration of BMP9 has been proposed as a potential therapeutic strategy against PAH, although recent conflicting evidence dispute the effect of such a practice. Considering the involvement of the above molecules in PAH onset, progression, and therapeutic value, we examined the effects of modulation of BMP9, BMPR2, and AQP1 on BMP9, BMP10, BMPR2, AQP1, and TGFB1 expression in human pulmonary microvascular endothelial cells in vitro. Our results demonstrated that silencing the BMPR2 gene resulted in increased expression of its two main ligands, namely BMP9 and BMP10. Exogenous administration of BMP9 caused the return of BMP10 to basal levels, while it restored the decreased AQP1 protein levels and the decreased TGFB1 mRNA and protein expression levels caused by BMPR2 silencing. Moreover, AQP1 gene silencing also resulted in increased expression of BMP9 and BMP10. Our results might possibly imply that the effect of exogenously administered BMP9 on molecules participating in the BMP signaling pathway could depend on the expression levels of BMPR2. Taken together, these results may provide insight into the highly complex interactions of the BMP signaling pathway.

Possible Hereditary Pulmonary Arterial Hypertension: from Clinical to Genetic Investigation in Precision Medicine Era

Background: Pulmonary Hypertension is a life-threatening disease characterized by a progressive increase of pulmonary vascular resistance that often leads to right ventricular (RV) failure and death. Major discoveries have been obtained within the last decade in the field of hereditary predisposition to pulmonary arterial hypertension (PAH). At least 6% of all PAH cases are familial in origin known as Familial Pulmonary Arterial Hypertension (FPAH) and display autosomal dominant inheritance with incomplete penetrance. While early diagnosis is associated with improved long-term survival, however at present, most patients are diagnosed at a very advanced stage of HPAH indicating that the early screening for HPAH is crucial. In this regard, genetic testing is an effective strategy for the early diagnosis and management of PAH, specifically Hereditary Pulmonary Arterial Hypertension (HPAH). We present two cases of Familial Pulmonary Arterial Hypertension and in-depth analysis of diagnostic cascade to allow an earlier and more reliable diagnosis of possible Hereditary Pulmonary Arterial Hypertension (HPAH). Case Illustration: Familial cases, a 44-years old man and his son a 17-years old boy, came with chief complaint of dyspnea. His daughter or his sister passed away when 4 years old due to PH. Both patients had been subsequently diagnosed with PAH with possible HPAH after the exclusion of primary and secondary heart anomalies using electrocardiography, echocardiography, and cardiac marker test. Both patients subsequently were performed right heart catheterization (RHC). Conclusions: We describe familial cases of pulmonary hypertension with clinically presenting right-sided heart failure. Diagnostic investigation was performed according to recent guideline to rule out and rule in all the possible cause of pulmonary hypertension. However, the final assessment showed unknown cause of pre-capillary pulmonary hypertension. Therefore, genetic investigation should be performed in precision medicine era due to high possibility of hereditary pulmonary arterial hypertension.

Dysregulated Smooth Muscle Cell BMPR2-ARRB2 Axis Causes Pulmonary Hypertension.

Mutations in BMPR2 (bone morphogenetic protein receptor 2) are associated with familial and sporadic pulmonary arterial hypertension (PAH). The functional and molecular link between loss of BMPR2 in pulmonary artery smooth muscle cells (PASMC) and PAH pathogenesis warrants further investigation, as most investigations focus on BMPR2 in pulmonary artery endothelial cells. Our goal was to determine whether and how decreased BMPR2 is related to the abnormal phenotype of PASMC in PAH. SMC-specific Bmpr2-/- mice (BKOSMC) were created and compared to controls in room air, after 3 weeks of hypoxia as a second hit, and following 4 weeks of normoxic recovery. Echocardiography, right ventricular systolic pressure, and right ventricular hypertrophy were assessed as indices of pulmonary hypertension. Proliferation, contractility, gene and protein expression of PASMC from BKOSMC mice, human PASMC with BMPR2 reduced by small interference RNA, and PASMC from PAH patients with a BMPR2 mutation were compared to controls, to investigate the phenotype and underlying mechanism. BKOSMC mice showed reduced hypoxia-induced vasoconstriction and persistent pulmonary hypertension following recovery from hypoxia, associated with sustained muscularization of distal pulmonary arteries. PASMC from mutant compared to control mice displayed reduced contractility at baseline and in response to angiotensin II, increased proliferation and apoptosis resistance. Human PASMC with reduced BMPR2 by small interference RNA, and PASMC from PAH patients with a BMPR2 mutation showed a similar phenotype related to upregulation of pERK1/2 (phosphorylated extracellular signal related kinase 1/2)-pP38-pSMAD2/3 mediating elevation in ARRB2 (β-arrestin2), pAKT (phosphorylated protein kinase B) inactivation of GSK3-beta, CTNNB1 (β-catenin) nuclear translocation and reduction in RHOA (Ras homolog family member A) and RAC1 (Ras-related C3 botulinum toxin substrate 1). Decreasing ARRB2 in PASMC with reduced BMPR2 restored normal signaling, reversed impaired contractility and attenuated heightened proliferation and in mice with inducible loss of BMPR2 in SMC, decreasing ARRB2 prevented persistent pulmonary hypertension. Agents that neutralize the elevated ARRB2 resulting from loss of BMPR2 in PASMC could prevent or reverse the aberrant hypocontractile and hyperproliferative phenotype of these cells in PAH.

Characteristics of Patients With Pulmonary Arterial Hypertension in a Pulmonary Hypertension Association-Accredited Comprehensive Care Center: A Contrast in Features When Compared With US National Registry Data.

Background Since the initial description in the 1980s, our understanding of the diversity of pulmonary arterial hypertension (PAH) has continued to evolve. In this study, we report the characteristics of patients seen in an academic medical center for PAH from August 2020 through November 2021 and contrast those with nationally reported data from the United States Pulmonary Hypertension Scientific Registry (USPHSR). Study Design Investigators at the University of Utah Pulmonary Hypertension Program prospectively enrolled adult patients diagnosed with WHO Group 1 PAH, who were evaluated between August 2020 and November 2021 in a program-specific registry. Patient exposure and health histories were collected through structured interviews and questionnaires, along with clinical data and medication use. A total of 242 patients were enrolled in the University of Utah Pulmonary Hypertension Registry (UUPHR). Results Of the 242 enrolled patients, the most common etiology was associated PAH (APAH), accounting for 71.1% of the population. The second largest etiology was idiopathic PAH (IPAH) at 26.4%. The remaining patients were distributed between familial PAH (FPAH), pulmonary veno-occlusive disease (PVOD), and others. Of the total population classified as APAH, 39% of cases were noted as secondary to connective tissue disease (CTD) and 33% as toxin-induced. These represented 28% and 24% of the total population, respectively. Conclusions In this US-based accredited academic medical center, the etiology of PAH in our patient population contrasts with national registry data. In the UUPHR, APAH, specifically CTD-PAH and toxin-associated PAH, accounts for the majority of patients with PAH. This contrasts with IPAH, which nationally is the most reported cause of PAH. Differences in our population may reflect the regional variation of the referral site, but it is noteworthy for its contrast with historically reported phenotypes.

MED1 Regulates BMP/TGF-β in Endothelium: Implication for Pulmonary Hypertension.

Dysregulated BMP (bone morphogenetic protein) or TGF-β (transforming growth factor beta) signaling pathways are imperative in idiopathic and familial pulmonary arterial hypertension (PAH) as well as experimental pulmonary hypertension (PH) in rodent models. MED1 (mediator complex subunit 1) is a key transcriptional co-activator and KLF4 (Krüppel-like factor 4) is a master transcription factor in endothelium. However, MED1 and KLF4 epigenetic and transcriptional regulations of the BMP/TGF-β axes in pulmonary endothelium and their dysregulations leading to PAH remain elusive. We investigate the MED1/KLF4 co-regulation of the BMP/TGF-β axes in endothelium by studying the epigenetic regulation of BMPR2 (BMP receptor type II), ETS-related gene (ERG), and TGFBR2 (TGF-β receptor 2) and their involvement in the PH. High-throughput screening involving data from RNA-seq, MED1 ChIP-seq, H3K27ac ChIP-seq, ATAC-seq, and high-throughput chromosome conformation capture together with in silico computations were used to explore the epigenetic and transcriptional regulation of BMPR2, ERG, and TGFBR2 by MED1 and KLF4. In vitro experiments with cultured pulmonary arterial endothelial cells (ECs) and bulk assays were used to validate results from these in silico analyses. Lung tissue from patients with idiopathic PAH, animals with experimental PH, and mice with endothelial ablation of MED1 (EC-MED1-/-) were used to study the PH-protective effect of MED1. Levels of MED1 were decreased in lung tissue or pulmonary arterial endothelial cells from idiopathic PAH patients and rodent PH models. Mechanistically, MED1 acted synergistically with KLF4 to transactivate BMPR2, ERG, and TGFBR2 via chromatin remodeling and enhancer-promoter interactions. EC-MED1-/- mice showed PH susceptibility. In contrast, MED1 overexpression mitigated the PH phenotype in rodents. A homeostatic regulation of BMPR2, ERG, and TGFBR2 in ECs by MED1 synergistic with KLF4 is essential for the normal function of the pulmonary endothelium. Dysregulation of MED1 and the resulting impairment of the BMP/TGF-β signaling is implicated in the disease progression of PAH in humans and PH in rodent models.

Comparison of intravenous sildenafil with inhaled nitric oxide for acute vasodilator testing in pulmonary arterial hypertension.

Acute vasodilator testing (AVT) identifies acute responders for initiation of calcium channel blockers in pulmonary arterial hypertension (PAH) and operability in congenital heart disease (CHD). We sought to determine the feasibility of intravenous sildenafil (ivS) as an alternative to inhaled nitric oxide (iNO) in AVT. All patients with PAH undergoing cardiac catheterization for AVT (November 2015 to December 2020) were prospectively enrolled. Hemodynamic data were obtained at baseline, with iNO 20 ppm and ivS (0.25 mg/kg for children and 10 mg for adults). We studied 44 patients with a mean age of 20.5 ± 14.4 years (27 [61%] females and 20 [45%]children). There were 17 (38.6%) patients in theCHD group for operability assessment and 27 patients in non-CHD group (idiopathic pulmonary arterial hypertension-16 [36.3%], residual PAH after shunt closure-7 [15.9%], and 2 cases [4.5%] each of familial PAH and portopulmonary hypertension). There was an excellent intraclass correlation for mean pulmonary artery pressures (0.903, 95% confidence interval,CI: 0.809-0.949, p < 0.001), mean aortic pressures (0.745, 95% CI: 0.552-0.858, p < 0.001), pulmonary vascular resistance index (0.920, 95% CI: 0.858-0.956, p < 0.001), systemic vascular resistance (SVR) index (0.828, 95% CI: 0.706-0.902, p < 0.001), and the ratio of pulmonary and SVR indices (0.857, 95% CI: 0.752-0.919, p < 0.001) between the two agents. There were two responders, both in non-CHD group, and were identified by iNO and ivS. The hemodynamic effects of ivS show excellent correlation with iNO and could be a potential alternative agent for identifying acute responders during AVT.

Clinical Implications of the Genetic Background in Pediatric Pulmonary Arterial Hypertension: Data from the Spanish REHIPED Registry.

Background: Pulmonary arterial hypertension (PAH) is a severe and rare disease with an important genetic background. The influence of genetic testing in the clinical classification of pediatric PAH is not well known and genetics could influence management and prognosis. Objectives: The aim of this work was to identify the molecular fingerprint of PH children in the REgistro de pacientes con HIpertensión Pulmonar PEDiátrica (REHIPED), and to investigate if genetics could have an impact in clinical reclassification and prognosis. Methods: We included pediatric patients with a genetic analysis from REHIPED. From 2011 onward, successive genetic techniques have been carried out. Before genetic diagnosis, patients were classified according to their clinical and hemodynamic data in five groups. After genetic analysis, the patients were reclassified. The impact of genetics in survival free of lung transplantation was estimated by Kaplan–Meier curves. Results: Ninety-eight patients were included for the analysis. Before the genetic diagnoses, there were idiopathic PAH forms in 53.1%, PAH associated with congenital heart disease in 30.6%, pulmonary veno-occlusive disease—PVOD—in 6.1%, familial PAH in 5.1%, and associated forms with multisystemic disorders—MSD—in 5.1% of the patients. Pathogenic or likely pathogenic variants were found in 44 patients (44.9%). After a genetic analysis, 28.6% of the cohort was “reclassified”, with the groups of heritable PAH, heritable PVOD, TBX4, and MSD increasing up to 18.4%, 8.2%, 4.1%, and 12.2%, respectively. The MSD forms had the worst survival rates, followed by PVOD. Conclusions: Genetic testing changed the clinical classification of a significant proportion of patients. This reclassification showed relevant prognostic implications.

Genetic and functional analyses of TBX4 reveal novel mechanisms underlying pulmonary arterial hypertension

BackgroundPulmonary arterial hypertension (PAH) is a fatal disease, with approximately 10% of cases associated with genetic variants. Recent genetic studies have reported pathogenic variants in the TBX4 gene in patients with PAH, especially in patients with childhood-onset of the disease, but the pathogenesis of PAH caused by TBX4 variant has not been fully uncovered. MethodsWe analysed the TBX4 gene in 75 Japanese patients with sporadic or familial PAH using a PCR-based bidirectional sequencing method. Detected variants were evaluated using in silico analyses as well as in vitro analyses including luciferase assay, immunocytochemistry and chromatin immunoprecipitation (ChIP) whether they have altered function. We also analysed the function of TBX4 using mouse embryonic lung explants with inhibition of Tbx4 expression. ResultsPutative pathogenic variants were detected in three cases (4.0%). Our in vitro functional analyses revealed that TBX4 directly regulates the transcriptional activity of fibroblast growth factor 10 (FGF10), whereas the identified TBX4 variant proteins failed to activate the FGF10 gene because of disruption of nuclear localisation signal or poor DNA-binding affinity. Furthermore, ex vivo inhibition of Tbx4 resulted in insufficiency of lung morphogenesis along with specific downregulation of Tie2 and Kruppel-like factor 4 expression. ConclusionOur results implicate variants in TBX4 as a genetic cause of PAH in a subset of the Japanese population. Variants in TBX4 may lead to PAH through insufficient lung morphogenesis by disrupting the TBX4-mediated direct regulation of FGF10 signalling and pulmonary vascular endothelial dysfunction involving PAH-related molecules.

Abstract 108: Mediator 1 Regulation Of The BMP / TGF-β Signaling In Endothelium: Implications For Pulmonary Hypertension

Rationale: Dysregulated bone morphogenetic protein (BMP) or transforming growth factor β (TGF-β) signaling pathways are imperative in idiopathic and familial pulmonary arterial hypertension (PAH) as well as experimental pulmonary hypertension (PH) in rodent models. Mediator 1 (MED1) is a key transcriptional coactivator and Krüppel-like factor 4 (KLF4) is a master transcription factor in endothelium. However, MED1 and KLF4 epigenetic and transcriptional regulations of the BMP/TGF-β axes in pulmonary endothelium and their dysregulations leading to PAH remain elusive. Objectives: We investigate the MED1/KLF4 co-regulation of the BMP/TGF-β axes in endothelium by studying the epigenetic regulation of BMP receptor type II (BMPR2), ETS-related gene (ERG), and TGF-β receptor 2 (TGFBR2) and their involvement in the PH. Methods: High throughput screening involving data from RNA-seq, MED1 ChIP-seq, H3K27ac ChIP-seq, KLF4 ATAC-seq, and high-throughput chromosome conformation capture (HiC) together with in silico computations were used to explore the epigenetic and transcriptional regulation of BMPR2, ERG, and TGFBR2 by MED1 and KLF4. In vitro experiments with cultured pulmonary arterial endothelial cells (PAECs) and bulk assays were used to validate results from these in silico analyses. Lung tissue from patients with idiopathic pulmonary arterial hypertension (IPAH), animals with experimental PH, and mice with endothelial ablation of MED1 (EC-MED1 -/- ) were used to study the PH-protective effect of MED1. Results: Levels of MED1 were decreased in lung tissue or PAECs from IPAH patients and rodent PH models. Mechanistically, MED1 acted synergistically with KLF4 to transactivate BMPR2, ERG, and TGFBR2 via chromatin remodeling and enhancer-promoter interactions. EC-MED1 -/- mice showed PH susceptibility. In contrast, MED1 overexpression mitigated the PH phenotype in rodents. Conclusions: A homeostatic regulation of BMPR2, ERG, and TGFBR2 in ECs by MED1 synergistic with KLF4 is essential for normal function of the pulmonary endothelium. Dysregulation of MED1 and the resulting impairment of the BMP/TGF-β signaling can lead to the development of PAH/PH.

PH Professional Network: Genetic Counseling and Pulmonary Arterial Hypertension

PH Professional Network: Genetic Counseling and Pulmonary Arterial Hypertension

Genetic Counseling and Testing for Pulmonary Arterial Hypertension in the United States

Genetic Counseling and Testing for Pulmonary Arterial Hypertension in the United States

PH Roundtable: Genetics and Pulmonary Hypertension

PH Roundtable: Genetics and Pulmonary Hypertension

Abstract 14272: Whole Exome Sequence Analysis of Pulmonary Hypertension in the UK Biobank

Introduction: Pulmonary hypertension (PH) is a progressive disease characterized by adverse remodeling of the lung vasculature and right ventricular failure. While BMPR2 mutations account for the majority of familial pulmonary arterial hypertension (PAH), the predisposing genetic factors in non-familial PH are not well understood. Whole exome sequencing (WES) data from individuals in the UK Biobank (UKB) provides a unique opportunity to interrogate the genetic factors underlying this rare disease. Hypothesis: Rare disruptive coding variants associated with sporadic PH will provide novel mechanistic insights. Methods: Exome sequences were aligned to the GRCh38 reference genome and variants annotated using Variant Effect Predictor. We identified rare (minor allele frequency &lt;1%) high confidence loss-of-function variants using LOFTEE and deleterious missense variants using MetaSVM. We then performed a rare variant burden association study using logistic regression in REGENIE adjusting for age, sex, array, smoking status, and principal components 1-10. These analyses were performed on unrelated individuals identified based on kinship (kinship &gt; 0.0884). We secondarily curated a list of 58 candidate PAH genes based on recent publications of rare variants identified in PAH, as well as the ClinVar database. PH was defined utilizing ICD codes 416.0 (ICD-9), I27.0, I27.2 (ICD-10). Results: 185,586 UKB participants were included; 665 with PH (age 62 years (+/-6), 46% female) and 184,921 controls (age 56 years (+/-8), 55% female). Rare variant association testing did not identify exome-significantly associated genes (p&lt;2.5x10 -7 ), nor nominal associations in candidate PAH genes. Four novel genes with p&lt;0.01 were identified, which included genes important in mitochondrial function ( ACADM ), nicotinic acetylcholine receptor signaling ( MYO18A ), pulmonary surfactant metabolism ( SFTPA1 ) and smooth muscle function ( BEST2 ). Conclusions: We identified putative genes associated with PH in the population which have not been previously implicated in familial PAH. If additional evidence supports the roles of these genes in PH, these findings may provide new therapeutic insights.

Genetic background in pediatric pulmonary arterial hypertension. Should we change the current recommendations for genetic testing?

Abstract Background Pulmonary arterial hypertension (PAH) is a rare and severe disease, genetically predisposed in a high proportion of patients. PAH is subclassified in different subtypes depending on the underlying condition. Gene variants are more frequent among heritable or idiopathic forms. Nevertheless, pathogenic variants have been described across the entire spectrum of this disease. Evidence regarding genetics in pediatric PAH is scarce [1]. Purpose Our aim is to describe the prevalence of significant gene mutations among a pediatric PAH cohort and to define specific data in the different subtypes. Methods Samples for genetic studies were obtained from blood tests of patients included in the Spanish National Registry of Pediatric Pulmonary Hypertension (REHIPED). Guardians signed informed consent before the inclusion in the study. Qualitative variables were compared by Chi-square test. Quantitative variables were assessed by Kruskal-Wallis, considering the asymmetric distribution of variables. STATA 14.0 was used for analyses. Results Sixty four patients were included between 2011 and 2021. Median age of the entire sample was 7.1 years (2.0–12.6) and 42.2% of them were male. There were significant differences in the age at diagnosis and race between the different included groups (table). Pathogenic or likely pathogenic variants were more frequent in familial pulmonary venooclusive disease (PVOD) and familial PAH cases. A similar percentage of mutations were found in idiopathic cases and in PAH associated with congenital heart disease (Figure). Gene variants in the gene encoding the bone morphogenetic protein receptor type 2 (BMPR2) were the most frequent mutations in the PAH familial cohort and there was also the most frequent finding in congenital heart disease and sporadic PAH, in conjunction with the TBX4 gene. Homozygous or compound heterozygous EIF2AK4 (eukaryotic translation initiation factor 2 a kinase 4) mutations were found in all the patients diagnosed with PVOD. Heritable PAH and PVOD cases were diagnosed more frequently after family screening. Conclusions This study shows a comparable proportion of pathogenic-likely pathogenic gene mutations in patients diagnosed of pulmonary arterial hypertension associated with congenital heart disease and idiopathic cases, with similar distribution of specific genes. BMPR2 and TBX 4 were the most frequent gene variants in this pediatric PAH population. BMPR2 and EIF2AK4 are the most common mutations in familial PAH and PVOD subtypes, respectively. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): ACU holds a Rio Hortega Grant from the Instituto de Salud Carlos III, Spanish Ministry of Science and Innovation.JAT and NG hold grants from FEDER (Federaciόn Española de Enfermedades Raras) and from the FCHP. Table 1. Characteristics of PAH subtypesFigure 1. PAH and ACMG classification.

Can serum 8-hydroxy-2'-deoxyguanosine levels reflect the severity of pulmonary arterial hypertension?

Oxidative stress plays a pivotal role in the pathogenesis of pulmonary arterial hypertension. 8-Hydroxy-2'-deoxyguanosine is a sensitive biomarker that reflects the degree of oxidative damage to DNA. We investigated whether serum 8-Hydroxy-2'-deoxyguanosine is a clinically useful biomarker for the severity of pulmonary arterial hypertension. We measured serum 8-Hydroxy-2'-deoxyguanosine levels in 25 patients (age 37±13 years, 68% women) diagnosed with idiopathic pulmonary arterial hypertension, familial pulmonary arterial hypertension, or pulmonary arterial hypertension associated with congenital heart disease. The severity of pulmonary arterial hypertension was evaluated by six-min walking distance, World Health Organization functional class, and serum brain natriuretic peptide levels. Age and gender-matched 22 healthy subjects served as the control group. The comparison of 8-Hydroxy-2'-deoxyguanosine levels between patients and controls was not statistically different [(19.86±9.79) versus (18.80±3.94) ng/mL, p=0.622)]. However, there was a significant negative correlation between 8-Hydroxy-2'-deoxyguanosine levels and six-min walking distance (r= -0.614, p=0.001). Additionally, serum 8-Hydroxy-2'-deoxyguanosine levels in patients with functional class III-IV were significantly higher than those with functional class I-II (functional class III-IV 32.31±10.63 ng/mL versus functional class I-II 16.74±6.81 ng/mL, respectively, p=0.003). The 8-Hydroxy-2'-deoxyguanosine levels were significantly correlated with exercise capacity (six-min walking distance) and symptomatic status (functional class), both of which show the severity of pulmonary arterial hypertension in patients.

Potts Shunt in Children With Familial Primary Pulmonary Hypertension: A Case Report and Brief Literature Review

Introduction: The primary concern about Familial Pulmonary Arterial Hypertension (FPAH) is the development of right heart failure, which ultimately leads to sudden death. Despite recent advances in pharmacological therapy, the mortality rate in children is still high, emphasizing the importance of novel treatments. Moreover, there is still no definitive treatment for children with severe pulmonary hypertension. The consequences of right heart failure led to the proposal of a surgical approach, the Potts shunt, to decompress the right ventricle, providing shunting of deoxygenated blood to lower extremities and improving overall cardiac output. This surgical technique creates an anastomosis between the left pulmonary artery and the descending aorta, providing a palliative treatment to off-load the right ventricle. Case Presentation: We report an 11-year-old girl with familial pulmonary arterial hypertension and right ventricular failure who benefited from a Potts shunt with good mid-term results. The patient was diagnosed at the age of 5 when she had a history of fainting and persistent syncope. The patient was under medical treatment therapy with bosentan, sildenafil, acetylsalicylic acid, and warfarin for six years. The results of molecular genetic testing, which was confirmed with direct sequencing of the Bone Morphogenetic Protein Receptor Type 2 (BMPR2) gene, revealed a heterozygous pathogenic mutation. Since she was diagnosed with Pulmonary Arterial Hypertension (PAH), she lost her grandmother, an aunt, and father because of PAH. Her 14-year-old sister also had mutated the BMPR2 gene without developing FPAH. Conclusions: The Potts shunt provides an interventional step for palliation of patients with familial pulmonary hypertension and severe right heart failure refractory to medical treatment. It opens the door to the possibility of lung transplantation in the future. We did not see any complications within 6 years after placing the Potts shunt.

Genetic Counseling and Testing in Pulmonary Arterial Hypertension.

A subgroup of patients diagnosed with pulmonary arterial hypertension (PAH) carry transmissible pathogenic gene mutations. For many of these patients, the heritable nature of their disease can only be uncovered by genetic testing. Because identification of PAH patients who carry pathogenic gene mutations has important implications for other family members, genetic counseling and testing should be offered to patients diagnosed with idiopathic or familial PAH. This review describes the current state of genetic counseling and testing for patients diagnosed with PAH.

Membranous Expression of Integrin α5β1 is Elevated in Endothelial Cells of Pulmonary Arterial Hypertension

Pulmonary Arterial Hypertension (PAH) is an incurable pathology characterized by remodeling of small pulmonary arteries leading to increased pulmonary vascular resistance and right ventricular heart failure. The endothelial dysfunction and endothelial-to-mesenchymal transition (EndoMT) observed in PAH contribute to the formation of plexiform lesions. Fibronectin is a commonly used molecular marker of EndoMT and is abundantly present in the plexiform lesions observed in human PAH. We have previously observed that pulmonary artery endothelial cells (PAECs) from the lesion forming Sugen/hypoxia rat model of PAH demonstrate increased proliferation and angiogenesis compared to PAECs from normoxic control animals. As the fibronectin receptor integrin α5β1 promotes endothelial proliferation and angiogenesis, we aimed to determine whether the expression of integrin α5β1 was elevated in PAH PAECs. Sugen/hypoxia rat PAECs (PAH PAECs) or normoxic control cells were received from the University of South Alabama. Initially, we observed an increase in mRNA expression of integrins α5, αV and β1 in PAH PAECs compared to control cells using a PCR screening array for molecular markers of epithelial-to-mesenchymal transition. Increased protein expression of the integrin α5, αV and β1 monomers were also observed in membrane fractions of PAH PAECs via western blot, compared to the cell membranes of control PAECs following a cell fractionation assay. To confirm the presence of the integrin α5β1 heterodimer at the membranes of PAH PAECs, co-immunoprecipitation of integrins α5 and β1 was performed from the membrane fractions of PAH and control PAECs. Following immunoprecipitation, western blot analysis demonstrated a strong coprecipitation of integrin α5 and β1 in membrane fractions of PAH PAECs, compared to weak coprecipitation in control PAECs. To confirm the increased membranous expression of integrin α5β1 in human tissue, human pulmonary endothelial cells from patients with idiopathic PAH (IPAH), familial PAH (FPAH) and control cells from failed donors (FD) were analyzed with an integrin-mediated cell adhesion array for cell surface expression of alpha and beta integrins. Human cells were provided by PHBI under the Pulmonary Hypertension Breakthrough Initiative (PHBI)*. Monomeric α5- and β1-mediated adhesion and heterodimeric α5β1-mediated adhesion were increased in IPAH and FPAH cells compared to FD control pulmonary endothelial cells. Collectively, these data strongly indicate that protein levels of the integrin α5β1 fibronectin receptor are increased at the cell membranes of pulmonary endothelial cells in PAH.

SOX17 Loss-of-Function Mutation Underlying Familial Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) refers to a rare, progressive disorder that is characterized by occlusive pulmonary vascular remodeling, resulting in increased pulmonary arterial pressure, right-sided heart failure, and eventual death. Emerging evidence from genetic investigations of pediatric-onset PAH highlights the strong genetic basis underpinning PAH, and deleterious variants in multiple genes have been found to cause PAH. Nevertheless, PAH is of substantial genetic heterogeneity, and the genetic defects underlying PAH in the overwhelming majority of cases remain elusive. In this investigation, a consanguineous family suffering from PAH transmitted as an autosomal-dominant trait was identified. Through whole-exome sequencing and bioinformatic analyses as well as Sanger sequencing analyses of the PAH family, a novel heterozygous SOX17 mutation, NM_022454.4: c.379C>T; p. (Gln127*), was found to co-segregate with the disease in the family, with complete penetrance. The nonsense mutation was neither observed in 612 unrelated healthy volunteers nor retrieved in the population genetic databases encompassing the Genome Aggregation Database, the Exome Aggregation Consortium database, and the Single Nucleotide Polymorphism database. Biological analyses using a dual-luciferase reporter assay system revealed that the Gln127*-mutant SOX17 protein lost the ability to transcriptionally activate its target gene NOTCH1. Moreover, the Gln127*-mutant SOX17 protein exhibited no inhibitory effect on the function of CTNNB1-encode β-catenin, which is a key player in vascular morphogenesis. This research firstly links SOX17 loss-of-function mutation to familial PAH, which provides novel insight into the molecular pathogenesis of PAH, suggesting potential implications for genetic and prognostic risk evaluation as well as personalized prophylaxis of the family members affected with PAH.