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Yes / Aberrant transforming growth factor-β (TGF-β) signaling activation is linked to pulmonary arterial hypertension (PAH). BMPR2 mutations perturb the balance between bone morphogenetic protein (BMP) and TGF-β pathways, leading to vascular remodeling, narrowing of the lumen of pulmonary vasculature, and clinical symptoms. This forum highlights the association of the TGF-β pathway with pathogenesis and therapeutic approaches. / Research carried out at Nasim laboratories is funded by GrowMedtech, the Royal Society, the Commonwealth Scholarship Commission (CSC) and the University of Bradford (UoB). N.S. is funded by the CSC and C.C.N. is partly funded by the UoB.

Pulmonary arterial hypertension (PAH) can be caused by pathogenic variants in the gene bone morphogenetic protein receptor 2 (BMPR2). While BMPR2 protein expression levels are known to be reduced in the lung tissue of heritable PAH (HPAH) patients, a systematic study evaluating expression in more easily accessible blood samples and its clinical relevance is lacking. Thus, we analyzed the BMPR2 mRNA expression in idiopathic/HPAH patients and healthy controls in blood by quantitative polymerase chain reaction and protein expression by enzyme-linked immunosorbent assay. Clinical parameters included right heart catherization, echocardiography, six-minute walking test and laboratory tests. BMPR2 variant-carriers (n = 23) showed significantly lower BMPR2 mRNA expression in comparison to non-carriers (n = 56) and healthy controls (n = 30; p < 0.0001). No difference in BMPR2 protein expression was detected. Lower BMPR2 mRNA expression correlated significantly with greater systolic pulmonary artery pressure and pulmonary vascular resistance. Higher BMPR2 mRNA expression correlated with greater glomerular filtration rate, cardiac index and six-minute walking distance. We demonstrated the feasibility to assess BMPR2 expression in blood and, for the first time, that BMPR2 mRNA expression levels are significantly reduced in variant carriers and correlated with clinical parameters. Further studies may evaluate the usefulness of BMPR2 mRNA expression in blood as a new marker for disease severity.

Background Pulmonary arterial hypertension (PAH) is a rare progressive disease with no known cure. Of various aetiologies, PAH in association with connective tissue disease (PAH-CTD) is the most rapidly progressive and difficult to treat. Management of PAH has evolved significantly in the past ten years since the introduction of oral therapies. Evidence for the efficacy of these agents outside randomised controlled trials is limited, but guidelines exist. Aim To measure the impact of first-line monotherapy with bosentan or sildenafil and the introduction of prescribing guidelines on outcomes in PAH-CTD. Methods Following a retrospective analysis of consecutive, incident, treatment-naive PAH-CTD cases identified by the ASPIRE registry, influences on outcome measures have been compared. First-line monotherapy episodes for 247 patients was analysed against four distinct endpoints: change in exercise capacity, WHO functional class, time on monotherapy and all-cause mortality. Results Treatment with bosentan or sildenafil resulted in clinical stability at 2 years for nearly 1/4 patients. No difference was identified between the groups in terms of either exercise capacity or WHO functional class. Sildenafil patients were found to remain on monotherapy longer than those prescribed bosentan. Patients prescribed sildenafil have improved survival over those treated with bosentan. Unexpected baseline differences in between groups may confound the results as the haemodynamics of the bosentan patients were more severe. Conclusions A significant number of patients with PAH-CTD remain clinically stable on monotherapy at 2 years. Both agents seem equally effective in this aggressive form of PAH. A novel endpoint “TOM” may be of value in future research assessing response to treatment.

Pulmonary arterial hypertension is a rare, chronic disease characterized by progressive remodeling of the pulmonary vasculature. Historically, prognosis has been very poor with relatively low 3-year survival rates. Common symptoms include fatigue and shortness of breath upon exercise, chest pain, and syncope. Patients exhibit increased pressure and resistance in pulmonary arteries due to fibrosis, vessel narrowing, and elevated levels of vasoconstrictive agents; diagnosis is confirmed by right heart catheterization. Reduced blood flow through the pulmonary vasculature not only reduces the amount of oxygenated blood available for the systemic circulation, but increases afterload on the right ventricle and, if left untreated, ultimately causes right ventricular heart failure. In the past, few medications were available to pulmonary arterial hypertension patients. However, recent advancements in our molecular understanding of the disease have led to the development of new therapeutic options that show promise of slowing, or in some cases reversing, disease progression. Currently available treatments have been shown to significantly improve 3-year survival rates and help promote a better quality of life for patients. While an exact molecular or genetic mechanism of disease progression is not yet known, several studies have noted the presence of dysfunctional endothelial cells and an imbalance in molecular modulators of the pulmonary vasculature. Specifically, patients exhibit chronically low levels of vasodilating agents such as prostacyclin and nitric oxide. In addition, there is a heightened vasoconstrictive effect due to elevated endothelin-1 and thromboxane A2. Drugs have been developed to target these signaling pathways and show considerable promise and efficacy for managing pulmonary hypertension in patients. Although these therapeutics have been shown to significantly improve survival rates and symptoms, many have complex and inconvenient administration protocols and a host of adverse side effects. Moreover, many require monitoring or frequent follow up visits due to their off-target effects. Recent innovative advancements in pulmonary arterial hypertension pharmaceuticals hope to deliver safe, efficacious treatment options to patients debilitated by this chronic disease.

A hipertensão arterial pulmonar (HAP) é uma doença grave, caracterizada pelo aumento na resistência vascular pulmonar, elevando a pós-carga imposta ao ventrículo direito. Na tentativa de compensar o aumento da pós-carga, o ventrículo direito desenvolve hipertrofia, que pode evoluir para dilatação e insuficiência, síndrome conhecida como Cor pulmonale. Alterações no estado redox estão presentes na HAP e estão relacionadas ao remodelamento e insuficiência do ventrículo direito. Desta forma, as espécies reativas de oxigênio podem ser alvos terapêuticos interessantes na HAP. O sulforafano é um fitoquímico que vem sido largamente estudado pelo seu potencial de indução de enzimas antioxidantes. Dessa forma, este estudo analisou a influência do tratamento com sulforafano sobre o remodelamento do ventrículo direito e estado redox em um modelo experimental de HAP induzido por monocrotalina. O projeto foi submetido ao Comitê de Ética em Pesquisa com Animais da Universidade Federal do Rio Grande do Sul e aprovado sob o número 26270. Foram utilizados ratos Wistar machos, separados em quatro grupos (n=10-12 animais/grupo): controle (C); Controle + Sulforafano (CS); Monocrotalina (M); Monocrotalina + Sulforafano (MS). A indução da HAP foi realizada por meio de uma dose única de monocrotalina (60 mg/kg – i.p.). O tratamento com sulforafano (2,5 mg/kg i.p.) foi iniciado no 7º dia após a injeção de monocrotalina até 20º dia. Após 21 dias da indução da HAP, os ratos foram anestesiados e foi realizada ecocardiografia, cateterismo e eutanásia dos animais. Os resultados foram analisados através de ANOVA de duas vias e pós-teste de Student Newman Keuls (nível de significância P <0,05). Os resultados serão apresentados na versão completa desta dissertação. / Pulmonary arterial hypertension (PAH) is a serious disease characterized by an increase in pulmonary vascular resistance, increasing afterload imposed on the right ventricle. In an attempt to offset the increased afterload, right ventricular hypertrophy develops, which may progress to dilatation and failure, syndrome known as Cor pulmonale. Alterations in redox state are present in PAH and are related to remodeling and right ventricular failure. Thus, reactive oxygen species may be interesting drug targets in PAH. Sulforaphane is a phytochemical that has been widely studied for its potential induction of antioxidant enzymes. Thus, this study examined the influence of treatment with sulforaphane on the remodeling of the right ventricle and redox state in an experimental model of PAH-induced monocrotaline. The project was submitted to the Comitê de Ética em Pesquisa com Animais of the Universidade Federal do Rio Grande do Sul and approved under number 26270. Male Wistar rats were divided into four groups (n = 10-12 animals/group): Control (C); Control + Sulforaphane (CS); Monocrotaline (M); Sulforaphane + Monocrotaline (MS). Induction of PAH was performed by a single dose of monocrotaline (60 mg/kg - i.p.). The treatment with sulforaphane (2.5 mg/kg i.p.) was initiated on day 7 after injection of monocrotaline to 20 days. After 21 days of induction of PAH, rats were anesthetized and was performed echocardiography, catheterization and euthanasia of the animals. Results were analyzed by two-way ANOVA and Student Newman Keuls post-test (significance level P <0.05). Results will be presented in the full version.

L’hypertension artérielle pulmonaire (HTAP) correspond à un groupe de maladies qui se caractérise par une obstruction vasculaire suite à une vasoconstriction excessive, une prolifération cellulaire et la création de thromboses in situ, conduisant à une augmentation progressive des résistances vasculaires pulmonaires puis au décès. De nombreuses avancées dans la prise en charge de l’HTAP ont été réalisées ces dernières années avec la mise à disposition de médicaments principalement vasodilatateurs. Cependant, aucun de ces médicaments n’est curatif de la maladie témoignant de la nécessité à obtenir de nouvelles thérapeutiques. Des molécules axant leur effet sur la lutte contre la prolifération cellulaire liée à l’activation des récepteurs à tyrosine-kinases (RTK) ou le stress oxydant (SO) paraissent aujourd’hui comme de potentielles innovations thérapeutiques dans l’HTAP. Cependant, à l’heure actuelle, les données sur le SO dans l’HTAP sont trop peu détaillées pour cibler correctement cette voie physiopathologique. De même, les inhibiteurs de tyrosine-kinases ont montré un bénéfice dans la prise en charge de l’HTAP mais associé à des effets indésirables graves tels qu’une toxicité cardiaque. Dans ce travail, nous avons approfondi le mécanisme d’action du SO dans la physiopathologie de l’HTAP et complété l’identification des RTK dans le remodelage vasculaire pulmonaire afin de permettre la mise au point de thérapeutiques efficaces avec un rapport bénéfice risque favorable pour le patient. / Pulmonary arterial hypertension (PAH) corresponds to a group of diseases characterized by a vascular obstruction due to vasoconstriction, cellular proliferation and in situ thrombosis, leading to a progressive increase in pulmonary vascular resistances. New knowledge in the PAH management were performed in the last few years, specifically for vasodilators. However, none of those treatments cure the disease and new drugs are still needed. Molecules targeting cellular proliferation induced by tyrosine kinases receptors (TKR) activation or oxidative stress (OS) seem to be potential therapeutic innovations. However, knowledge on OS in PAH is not enough accomplished in PAH to target accurately this pathophysiologic pathway. Similarly, tyrosine kinase inhibitors have shown efficacy in PAH management but associated with severe adverse events as cardiac toxicity. In this study, mechanism of action of OS in pathophysiology of PAH was detailed and identification of TKR involved in vascular remodeling was completed in order to find efficient therapeutics with a favorable risk benefit ratio for PAH patient.

The rare disease pulmonary arterial hypertension (PAH) results in high blood pressure in the lung caused by narrowing of lung arteries. Genes causative in PAH were discovered through family studies and very often harbour rare variants. However, the genetic cause in heritable (31%) and idiopathic (79%) PAH cases is not yet known but are speculated to be caused by rare variants. Advances in high-throughput sequencing (HTS) technologies made it possible to detect variants in 98% of the human genome. A drop in sequencing costs made it feasible to sequence 10,000 individuals including 1,250 subjects diagnosed with PAH and relatives as part of the NIHR Bioresource - Rare (BR-RD) disease study. This large cohort allows the genome-wide identification of rare variants to discover novel causative genes associated with PAH in a case-control study to advance our understanding of the underlying aetiology. In the first part of my thesis, I establish a phenotype capture system that allows research nurses to record clinical measurements and other patient related information of PAH patients recruited to the NIHR BR-RD study. The implemented extensions provide a programmatic data transfer and an automated data release pipeline for analysis ready data. The second part is dedicated to the discovery of novel disease genes in PAH. I focus on one well characterised PAH disease gene to establish variant filter strategies to enrich for rare disease causing variants. I apply these filter strategies to all known PAH disease genes and describe the phenotypic differences based on clinically relevant values. Genome-wide results from different filter strategies are tested for association with PAH. I describe the findings of the rare variant association tests and provide a detailed interrogation of two novel disease genes. The last part describes the data characteristics of variant information, available non SQL (NoSQL) implementations and evaluates the suitability and scalability of distributed compute frameworks to store and analyse population scale variation data. Based on the evaluation, I implement a variant analysis platform that incrementally merges samples, annotates variants and enables the analysis of 10,000 individuals in minutes. An incremental design for variant merging and annotation has not been described before. Using the framework, I develop a quality score to reduce technical variation and other biases. The result from the rare variant association test is compared with traditional methods.

The apelin system is an evolving transmitter system consisting of the G protein coupled apelin receptor and two endogenous peptide ligands, apelin and elabela. It is implicated as a potential therapeutic for a number of diseases; however, the endogenous peptides are limited by half-life and bioavailability. This study aims to identify and pharmacologically characterise apelin agonists in vitro and in vivo and to evaluate their therapeutic potential in pulmonary arterial hypertension as a model disease. CMF-019 was identified as the first G protein biased apelin agonist. To date, suitable small molecule apelin agonists as experimental tool compounds have been limited and CMF-019 represents an important advance. CMF-019 was active in vivo, producing an increase in cardiac contractility and vasodilatation, similar to apelin. These effects were achieved without receptor desensitisation, supporting the remarkable G protein bias observed in vitro. Furthermore, it was disease-modifying in vitro in an endothelial cell apoptosis assay but despite this, did not prevent pulmonary arterial hypertension in a monocrotaline rat model of the disease. An apelin mimetic peptide possessing an unnatural amino acid, MM202, conjugated chemically via a polyethylene glycol linker to an anti-serum domain antibody (AlbudAb) was also characterised. The product MM202-AlbudAb represents the first time an AlbudAb has been conjugated chemically to an unnatural peptide mimetic, providing protection from proteolysis and glomerular filtration. Importantly, it retained binding to albumin and demonstrated in vitro and in vivo activity at the apelin receptor. In conclusion, this thesis has identified and pharmacologically characterised two novel apelin agonists that possess significant advantages over the endogenous peptides. CMF-019 is suitable as an experimental tool compound and, as the first G protein biased small molecule, provides a starting point for more suitable therapeutics. In addition, MM202-AlbudAb proves that unnatural peptides can be conjugated to AlbudAb, supporting use of this technology in other small-peptide ligand transmitter systems.