Sex Differences in Pulmonary Hypertension

Deep learning-driven pulmonary artery and vein segmentation reveals demography-associated vasculature anatomical differences

Pulmonary artery-vein segmentation is critical for disease diagnosis and surgical planning. Traditional methods rely on Computed Tomography Pulmonary Angiography (CTPA), which requires contrast agents with potential health risks. Non-contrast CT, a safer and more widely available approach, however, has long been considered impossible for this task. Here we propose High-abundant Pulmonary Artery-vein Segmentation (HiPaS), enabling accurate segmentation across both non-contrast CT and CTPA at multiple resolutions. HiPaS integrates spatial normalization with an iterative segmentation strategy, leveraging lower-level vessel segmentations as priors for higher-level segmentations. Trained on a multi-center dataset comprising 1073 CT volumes with manual annotations, HiPaS achieves superior performance (dice score: 91.8%, sensitivity: 98.0%) and demonstrates non-inferiority on non-contrast CT compared to CTPA. Furthermore, HiPaS enables large-scale analysis of 11,784 participants, revealing associations between vessel abundance and sex, age, and diseases, under lung-volume control. HiPaS represents a promising, non-invasive approach for clinical diagnostics and anatomical research.

Developing the evidence-base to inform policy on inclusive research design

Considering diversity when designing and conducting research is fundamental to the responsible conduct of research and ensures that outputs from scientific research are reproducible, minimize bias and enable everyone within society the opportunity to benefit. Therefore, health and biomedical research should include consideration of diversity and inclusion in the way studies are designed and conducted. An evaluation of health researchers' approaches to diversity was undertaken to generate evidence to inform research policy development by the UK Medical Research Council (MRC). Seven hundred and seventy-two researchers responded to an anonymized public survey about diversity and inclusion in research design and 590 applications for research funding were evaluated. Fifty per cent of survey respondents undertaking human participant research reported taking diversity, usually age and sex, into account. Although 43% of animal researchers reported using females and males, only 28% of grant applications demonstrated this. Our findings demonstrate that many researchers do not routinely consider diversity when designing research. Furthermore, we identified a gap between what animal researchers reported doing and what was evident in funding applications. Informed by this analysis, MRC implemented a new policy requiring researchers to demonstrate how they embed diversity and inclusion in research design. This survey provides a benchmark for evaluating policy impact.

Sex and gender differences during the lung lifespan: unveiling a pivotal impact

Sex and gender differences significantly influence lung parenchyma development, beginning as early as the embryonic stages of human life. Although this association is well known in the clinical manifestations of some relevant pulmonary diseases, there is less data available regarding their effects on cell biological programmes across different stages of body development. A deep understanding of these mechanisms could help in defining preventive strategies tailored to a fully personalised approach to respiratory medicine. From this perspective, this review aims to analyse the influence of sex and gender on bronchoalveolar and vascular compartments from embryonic and neonatal stages through to adolescence, adulthood and elder age.

Sex Dimorphism in Pulmonary Arterial Hypertension Associated With Autoimmune Diseases

Pulmonary hypertension is a rare, incurable, and progressive disease. Although there is increasing evidence that immune disorders, particularly those associated with connective tissue diseases, are a strong predisposing factor in the development of pulmonary arterial hypertension (PAH), there is currently a lack of knowledge about the detailed molecular mechanisms responsible for this phenomenon. Exploring this topic is crucial because patients with an immune disorder combined with PAH have a worse prognosis and higher mortality compared with patients with other PAH subtypes. Moreover, data recorded worldwide show that the prevalence of PAH in women is 2× to even 4× higher than in men, and the ratio of PAH associated with autoimmune diseases is even higher (9:1). Sexual dimorphism in the pathogenesis of cardiovascular disease was explained for many years by the action of female sex hormones. However, there are increasing reports of interactions between sex hormones and sex chromosomes, and differences in the pathogenesis of cardiovascular disease may be controlled not only by sex hormones but also by sex chromosome pathways that are not dependent on the gonads. This review discusses the role of estrogen and genetic factors including the role of genes located on the X chromosome, as well as the potential protective role of the Y chromosome in sexual dimorphism, which is prominent in the occurrence of PAH associated with autoimmune diseases. Moreover, an overview of animal models that could potentially play a role in further investigating the aforementioned link was also reviewed.

Assessment of genetic and clinical factors in T2D susceptibility among patients with hypertension

AIMS

Hypertension (HTN) and Type 2 Diabetes (T2D) often coexist, therefore understanding the relationship between both diseases is imperative to guide targeted prevention/therapy. This study aims to explore the relationship between HTN and T2D using genome-wide association study (GWAS) analysis and biochemical data to understand the implication of both clinical and genetic factors in these pathologies.

METHODS

A total of 2,876 patients were enrolled. Using GWAS and biochemical data, patients with both T2D and HTN were compared to patients with only HTN. Specificity was confirmed by testing the detected genetic variants for associations with HTN development in T2D patients, or with HTN in healthy subjects. Regression models were applied to examine the association of T2D in patients with HTN with cardiovascular risk factors. Replication was performed using UK Biobank dataset with 31,170 subjects.

RESULTS

Data showed that females with HTN are at higher risk of developing T2D due to dyslipidemia, while males faced higher risk due to high BMI (body mass index) and family history of T2D. GWAS identified Single Nucleotide Polymorphisms (SNPs) linked to T2D in patients with HTN. Notably, rs7865889, rs7756992, and rs10896290 were positively associated with T2D, whereas rs12737517 yielded negative association. Three SNPs were replicated in the UK Biobank (rs10896290, rs7865889, and rs7756992).

CONCLUSION

Incorporating clinical and genetic screening into risk assessment is important for the detection and prevention of T2D in patients with HTN. The detected SNPs (rs7865889, rs12737517, and rs10896290), especially the protective SNP (rs12737517), provide an opportunity for better diagnosis, prevention, and therapy of patients with T2D and HTN.

Bioinformatics approaches for studying molecular sex differences in complex diseases

Many complex diseases exhibit pronounced sex differences that can affect both the initial risk of developing the disease, as well as clinical disease symptoms, molecular manifestations, disease progression, and the risk of developing comorbidities. Despite this, computational studies of molecular data for complex diseases often treat sex as a confounding variable, aiming to filter out sex-specific effects rather than attempting to interpret them. A more systematic, in-depth exploration of sex-specific disease mechanisms could significantly improve our understanding of pathological and protective processes with sex-dependent profiles. This survey discusses dedicated bioinformatics approaches for the study of molecular sex differences in complex diseases. It highlights that, beyond classical statistical methods, approaches are needed that integrate prior knowledge of relevant hormone signaling interactions, gene regulatory networks, and sex linkage of genes to provide a mechanistic interpretation of sex-dependent alterations in disease. The review examines and compares the advantages, pitfalls and limitations of various conventional statistical and systems-level mechanistic analyses for this purpose, including tailored pathway and network analysis techniques. Overall, this survey highlights the potential of specialized bioinformatics techniques to systematically investigate molecular sex differences in complex diseases, to inform biomarker signature modeling, and to guide more personalized treatment approaches.

Hormonal influence: unraveling the impact of sex hormones on vascular smooth muscle cells

Sex hormones play a pivotal role as endocrine hormones that exert profound effects on the biological characteristics and vascular function of vascular smooth muscle cells (VSMCs). By modulating intracellular signaling pathways, activating nuclear receptors, and regulating gene expression, sex hormones intricately influence the morphology, function, and physiological state of VSMCs, thereby impacting the biological properties of vascular contraction, relaxation, and growth. Increasing evidence suggests that abnormal phenotypic changes in VSMCs contribute to the initiation of vascular diseases, including atherosclerosis. Therefore, understanding the factors governing phenotypic alterations in VSMCs and elucidating the underlying mechanisms can provide crucial insights for refining interventions targeted at vascular diseases. Additionally, the varying levels of different types of sex hormones in the human body, influenced by sex and age, may also affect the phenotypic conversion of VSMCs. This review aims to explore the influence of sex hormones on the phenotypic switching of VSMCs and the development of associated vascular diseases in the human body.

Sex differences in Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is an underdiagnosed sequela of acute pulmonary embolism with varied clinical presentation causing significant morbidity among the affected population. There exist important differences in the occurrence, clinical features and diagnosis of CTEPH between men and women, with women carrying a greater predisposition for the disease. Ongoing studies have also pointed out variations among men and women, in the treatment offered and long-term outcomes including mortality. This focused review article highlights important sex-associated differences in multiple aspects of CTEPH including its epidemiology, clinical features, diagnosis, treatment and outcomes as reported in current literature and highlights the need for future research to facilitate a clearer understanding of these differences.

Pulmonary Hypertension in Women

Pulmonary arterial hypertension (PAH) is a rare devastating disease characterized by elevated pulmonary artery pressure and increased pulmonary vascular resistance. Females have a higher incidence of PAH, which is reflected globally across registries in the United States, Europe, and Asia. However, despite female predominance, women had better outcomes compared with male patients, a finding that has been labeled the "estrogen paradox." Special considerations should be given to women with PAH regarding sexual health, contraception, family planning, and treatment before, during, and after pregnancy. Pregnant women with PAH should be referred to a pulmonary hypertension care center; a multidisciplinary team approach is recommended, and Cesarean section is the preferred mode of delivery. While pregnancy outcomes have improved over the years with PAH-specific therapy, pregnancy portends a high-risk for those with PAH. Continued research is needed to tailor PAH treatment for women.

Hydroxy-Safflower Yellow A Mitigates Vascular Remodeling in Rat Pulmonary Arterial Hypertension

Purpose

The underlying causes of pulmonary arterial hypertension (PAH) often remain obscure. Addressing PAH with effective treatments presents a formidable challenge. Studies have shown that Hydroxysafflor yellow A (HSYA) has a potential role in PAH, While the mechanism underlies its protective role is still unclear. The study was conducted to investigate the potential mechanisms of the protective effects of HSYA.

Methods

Using databases such as PharmMapper and GeneCards, we identified active components of HSYA and associated PAH targets, pinpointed intersecting genes, and constructed a protein-protein interaction (PPI) network. Core targets were singled out using Cytoscape for the development of a model illustrating drug-component-target-disease interactions. Intersection targets underwent analysis for Gene Ontology (GO) functions and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Selected components were then modeled for target interaction using Autodock and Pymol. In vivo validation in a monocrotaline-induced PAH (MCT-PAH) animal model was utilized to substantiate the predictions made by network pharmacology.

Results

We associated HSYA with 113 targets, and PAH with 1737 targets, identifying 34 mutual targets for treatment by HSYA. HSYA predominantly affects 9 core targets. Molecular docking unveiled hydrogen bond interactions between HSYA and several PAH-related proteins such as ANXA5, EGFR, SRC, PPARG, PGR, and ESR1.

Conclusion

Utilizing network pharmacology and molecular docking approaches, we investigated potential targets and relevant human disease pathways implicating HSYA in PAH therapy, such as the chemical carcinogenesis receptor activation pathway and the cancer pathway. Our findings were corroborated by the efficacious use of HSYA in an MCT-induced rat PAH model, confirming its therapeutic potential.

Pulmonary Hypertension in Underrepresented Minorities: A Narrative Review

Minoritized racial and ethnic groups suffer disproportionately from the incidence and morbidity of pulmonary hypertension (PH), as well as its associated cardiovascular, pulmonary, and systemic conditions. These disparities are largely explained by social determinants of health, including access to care, systemic biases, socioeconomic status, and environment. Despite this undue burden, minority patients remain underrepresented in PH research. Steps should be taken to mitigate these disparities, including initiatives to increase research participation, combat inequities in access to care, and improve the treatment of the conditions associated with PH.

Sex-biased TGFβ signalling in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare cardiovascular disorder leading to pulmonary hypertension and, often fatal, right heart failure. Sex differences in PAH are evident, which primarily presents with a female predominance and increased male severity. Disturbed signalling of the transforming growth factor-β (TGFβ) family and gene mutations in the bone morphogenetic protein receptor 2 (BMPR2) are risk factors for PAH development, but how sex-specific cues affect the TGFβ family signalling in PAH remains poorly understood. In this review, we aim to explore the sex bias in PAH by examining sex differences in the TGFβ signalling family through mechanistical and translational evidence. Sex hormones including oestrogens, progestogens, and androgens, can determine the expression of receptors (including BMPR2), ligands, and soluble antagonists within the TGFβ family in a tissue-specific manner. Furthermore, sex-related genetic processes, i.e. Y-chromosome expression and X-chromosome inactivation, can influence the TGFβ signalling family at multiple levels. Given the clinical and mechanistical similarities, we expect that the conclusions arising from this review may apply also to hereditary haemorrhagic telangiectasia (HHT), a rare vascular disorder affecting the TGFβ signalling family pathway. In summary, we anticipate that investigating the TGFβ signalling family in a sex-specific manner will contribute to further understand the underlying processes leading to PAH and likely HHT.

Endothelial FIS1 DeSUMOylation Protects Against Hypoxic Pulmonary Hypertension

BACKGROUND

Hypoxia is a major cause and promoter of pulmonary hypertension (PH), a representative vascular remodeling disease with poor prognosis and high mortality. However, the mechanism underlying how pulmonary arterial system responds to hypoxic stress during PH remains unclear. Endothelial mitochondria are considered signaling organelles on oxygen tension. Results from previous clinical research and our studies suggested a potential role of posttranslational SUMOylation (small ubiquitin-like modifier modification) in endothelial mitochondria in hypoxia-related vasculopathy.

METHODS

Chronic hypoxia mouse model and Sugen/hypoxia rat model were employed as PH animal models. Mitochondrial morphology and subcellular structure were determined by transmission electron and immunofluorescent microscopies. Mitochondrial metabolism was determined by mitochondrial oxygen consumption rate and extracellular acidification rate. SUMOylation and protein interaction were determined by immunoprecipitation.

RESULTS

The involvement of SENP1 (sentrin-specific protease 1)-mediated SUMOylation in mitochondrial remodeling in the pulmonary endothelium was identified in clinical specimens of hypoxia-related PH and was verified in human pulmonary artery endothelial cells under hypoxia. Further analyses in clinical specimens, hypoxic rat and mouse PH models, and human pulmonary artery endothelial cells and human embryonic stem cell-derived endothelial cells revealed that short-term hypoxia-induced SENP1 translocation to endothelial mitochondria to regulate deSUMOylation (the reversible process of SUMOylation) of mitochondrial fission protein FIS1 (mitochondrial fission 1), which facilitated FIS1 assembling with fusion protein MFN2 (mitofusin 2) and mitochondrial gatekeeper VDAC1 (voltage-dependent anion channel 1), and the membrane tethering activity of MFN2 by enhancing its oligomerization. Consequently, FIS1 deSUMOylation maintained the mitochondrial integrity and endoplasmic reticulum-mitochondria calcium communication across mitochondrial-associated membranes, subsequently preserving pulmonary endothelial function and vascular homeostasis. In contrast, prolonged hypoxia disabled the FIS1 deSUMOylation by diminishing the availability of SENP1 in mitochondria via inducing miR (micro RNA)-138 and consequently resulted in mitochondrial dysfunction and metabolic reprogramming in pulmonary endothelium. Functionally, introduction of viral-packaged deSUMOylated FIS1 within pulmonary endothelium in mice improved pulmonary endothelial dysfunction and hypoxic PH development, while knock-in of SUMO (small ubiquitin-like modifier)-conjugated FIS1 in mice exaggerated the diseased cellular and tissue phenotypes.

CONCLUSIONS

By maintaining endothelial mitochondrial homeostasis, deSUMOylation of FIS1 adaptively preserves pulmonary endothelial function against hypoxic stress and consequently protects against PH. The FIS1 deSUMOylation-SUMOylation transition in pulmonary endothelium is an intrinsic pathogenesis of hypoxic PH.

SOX17 Deficiency Mediates Pulmonary Hypertension: At the Crossroads of Sex, Metabolism, and Genetics

Rationale: Genetic studies suggest that SOX17 (SRY-related HMG-box 17) deficiency increases pulmonary arterial hypertension (PAH) risk. Objectives: On the basis of pathological roles of estrogen and HIF2α (hypoxia-inducible factor 2α) signaling in pulmonary artery endothelial cells (PAECs), we hypothesized that SOX17 is a target of estrogen signaling that promotes mitochondrial function and attenuates PAH development via HIF2α inhibition. Methods: We used metabolic (Seahorse) and promoter luciferase assays in PAECs together with the chronic hypoxia murine model to test the hypothesis. Measurements and Main Results: Sox17 expression was reduced in PAH tissues (rodent models and from patients). Chronic hypoxic pulmonary hypertension was exacerbated by mice with conditional Tie2-Sox17 (Sox17EC-/-) deletion and attenuated by transgenic Tie2-Sox17 overexpression (Sox17Tg). On the basis of untargeted proteomics, metabolism was the top pathway altered by SOX17 deficiency in PAECs. Mechanistically, we found that HIF2α concentrations were increased in the lungs of Sox17EC-/- and reduced in those from Sox17Tg mice. Increased SOX17 promoted oxidative phosphorylation and mitochondrial function in PAECs, which were partly attenuated by HIF2α overexpression. Rat lungs in males displayed higher Sox17 expression versus females, suggesting repression by estrogen signaling. Supporting 16α-hydroxyestrone (16αOHE; a pathologic estrogen metabolite)-mediated repression of SOX17 promoter activity, Sox17Tg mice attenuated 16αOHE-mediated exacerbations of chronic hypoxic pulmonary hypertension. Finally, in adjusted analyses in patients with PAH, we report novel associations between a SOX17 risk variant, rs10103692, and reduced plasma citrate concentrations (n = 1,326). Conclusions: Cumulatively, SOX17 promotes mitochondrial bioenergetics and attenuates PAH, in part, via inhibition of HIF2α. 16αOHE mediates PAH development via downregulation of SOX17, linking sexual dimorphism and SOX17 genetics in PAH.

Molecular Pathways in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension is a multifactorial, chronic disease process that leads to pulmonary arterial endothelial dysfunction and smooth muscular hypertrophy, resulting in impaired pliability and hemodynamics of the pulmonary vascular system, and consequent right ventricular dysfunction. Existing treatments target limited pathways with only modest improvement in disease morbidity, and little or no improvement in mortality. Ongoing research has focused on the molecular basis of pulmonary arterial hypertension and is going to be important in the discovery of new treatments and genetic pathways involved. This review focuses on the molecular pathogenesis of pulmonary arterial hypertension.

Serotonin and Pulmonary Hypertension; Sex and Drugs and ROCK and Rho

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.

Gender dimension in cardio-pulmonary continuum

Cardio-pulmonary diseases, which were once regarded as a man's illness, have been one of the leading causes of morbidity and mortality for both men and women in many countries in recent years. Both gender and sex influence the functional and structural changes in the human body and therefore play an important role in disease clinical manifestation, treatment choice, and/or response to treatment and prognosis of health outcomes. The gender dimension integrates sex and gender analysis in health sciences and medical research, however, it is still relatively overlooked suggesting the need for empowerment in the medical research community. Latest advances in the field of cardiovascular research have provided supportive evidence that the application of biological variables of sex has led to the understanding that heart disease in females may have different pathophysiology compared to males, particularly in younger adults. It has also resulted in new diagnostic techniques and a better understanding of symptomatology, while gender analysis has informed more appropriate risk stratification and prevention strategies. The existing knowledge in the pulmonary field shows the higher prevalence of pulmonary disorders among females, however, the role of gender as a socio-cultural construct has yet to be explored for the implementation of targeted interventions. The purpose of this review is to introduce the concept of gender dimension and its importance for the cardiopulmonary continuum with a focus on shared pathophysiology and disease presentation in addition to interrelation with chronic kidney disease. The review presents basic knowledge of what gender dimension means, and the application of sex and gender aspects in cardiovascular medicine with a specific focus on early pulmonary development, pulmonary hypertension, and chronic obstructive pulmonary disease (COPD). Early vascular aging and inflammation have been presented as a potential pathophysiological link, with further interactions between the cardiopulmonary continuum and chronic kidney disease. Finally, implications for potential future research have been provided to increase the impact of gender dimension on research excellence that would add value to everybody, foster toward precision medicine and ultimately improve human health.

Mice with humanized immune system as novel models to study HIV-associated pulmonary hypertension

People living with HIV and who receive antiretroviral therapy have a significantly improved lifespan, compared to the early days without therapy. Unfortunately, persisting viral replication in the lungs sustains chronic inflammation, which may cause pulmonary vascular dysfunction and ultimate life-threatening Pulmonary Hypertension (PH). The mechanisms involved in the progression of HIV and PH remain unclear. The study of HIV-PH is limited due to the lack of tractable animal models that recapitulate infection and pathobiological aspects of PH. On one hand, mice with humanized immune systems (hu-mice) are highly relevant to HIV research but their suitability for HIV-PH research deserves investigation. On another hand, the Hypoxia-Sugen is a well-established model for experimental PH that combines hypoxia with the VEGF antagonist SU5416. To test the suitability of hu-mice, we combined HIV with either SU5416 or hypoxia. Using right heart catheterization, we found that combining HIV+SU5416 exacerbated PH. HIV infection increases human pro-inflammatory cytokines in the lungs, compared to uninfected mice. Histopathological examinations showed pulmonary vascular inflammation with arterial muscularization in HIV-PH. We also found an increase in endothelial-monocyte activating polypeptide II (EMAP II) when combining HIV+SU5416. Therefore, combinations of HIV with SU5416 or hypoxia recapitulate PH in hu-mice, creating well-suited models for infectious mechanistic pulmonary vascular research in small animals.

Sex Differences and Similarities in Valvular Heart Disease

As populations age worldwide, the burden of valvular heart disease has grown exponentially, and so has the proportion of affected women. Although rheumatic valve disease is declining in high-income countries, degenerative age-related causes are rising. Calcific aortic stenosis and degenerative mitral regurgitation affect a significant proportion of elderly women, particularly those with comorbidities. Women with valvular heart disease have been underrepresented in many of the landmark studies which form the basis for guideline recommendations. As a consequence, surgical referrals in women have often been delayed, with worse postoperative outcomes compared with men. As described in this review, a more recent effort to include women in research studies and clinical trials has increased our knowledge about sex-based differences in epidemiology, pathophysiology, diagnostic criteria, treatment options, outcomes, and prognosis.

Caspase-4/11-Mediated Pulmonary Artery Endothelial Cell Pyroptosis Contributes to Pulmonary Arterial Hypertension

BACKGROUND

Endothelial dysfunction enhances vascular inflammation, which initiates pulmonary arterial hypertension (PAH) pathogenesis, further induces vascular remodeling and right ventricular failure. Activation of inflammatory caspases is an important initial event at the onset of pyroptosis. Studies have shown that caspase-1-mediated pyroptosis has played a crucial role in the pathogenesis of PAH. However, the role of caspase-11, another inflammatory caspase, remains to be elucidated. Therefore, the purpose of this study was to clarify the role of caspase-11 in the development of PAH and its mechanism on endothelial cell function.

METHODS

The role of caspase-11 in the progression of PAH and vascular remodeling was assessed in vivo. In vitro, the effect of caspase-4 silencing on the human pulmonary arterial endothelial cells pyroptosis was determined.

RESULTS

We confirmed that caspase-11 and its human homolog caspase-4 were activated in PAH animal models and TNF (tumor necrosis factor)-α-induced human pulmonary arterial endothelial cells. Caspase-11^-/- relieved right ventricular systolic pressure, right ventricle hypertrophy, and vascular remodeling in Sugen-5416 combined with chronic hypoxia mice model. Meanwhile, pharmacological inhibition of caspase-11 with wedelolactone exhibited alleviated development of PAH on the monocrotaline-induced rat model. Moreover, knockdown of caspase-4 repressed the onset of TNF-α-induced pyroptosis in human pulmonary arterial endothelial cells and inhibited the activation of pyroptosis effector GSDMD (gasdermin D) and GSDME (gasdermin E).

CONCLUSIONS

These observations identified the critical role of caspase-4/11 in the pyroptosis pathway to modulate pulmonary vascular dysfunction and accelerate the progression of PAH. Our findings provide a potential diagnostic and therapeutic target in PAH.

New Insights into Pulmonary Hypertension: A Role for Connexin-Mediated Signalling

Pulmonary hypertension is a serious clinical condition characterised by increased pulmonary arterial pressure. This can lead to right ventricular failure which can be fatal. Connexins are gap junction-forming membrane proteins which serve to exchange small molecules of less than 1 kD between cells. Connexins can also form hemi-channels connecting the intracellular and extracellular environments. Hemi-channels can mediate adenosine triphosphate release and are involved in autocrine and paracrine signalling. Recently, our group and others have identified evidence that connexin-mediated signalling may be involved in the pathogenesis of pulmonary hypertension. In this review, we discuss the evidence that dysregulated connexin-mediated signalling is associated with pulmonary hypertension.

Protective effects of progesterone on pulmonary artery smooth muscle cells stimulated with Interleukin 6 via blocking the shuttling and transcriptional function of STAT3

BACKGROUND

Sex hormone paradox is a crucial but unresolved issue in the field of pulmonary artery hypertension (PAH), and is thought to be related to different pathogenic factors. Inflammation is one of pathological mechanisms of PAH development. However, effects of sex hormones on the pulmonary vasculature under the condition of inflammation are still elusive.

METHODS

Interleukin-6 (IL-6) was used as a representative inflammatory stimulator. Effects of 17β-estradiol or progesterone on human pulmonary artery smooth muscle cells (PASMCs) were measured under the condition of IL-6. Cell functions of proliferation and migration were measured by Alarmar Blue, EdU assay, wound-healing assay and transwell chambers. We explored further mechanisms using western blot, immunofluorescence, co-immunoprecipitation, qPCR and chromatin immunoprecipitation.

RESULTS

Our results revealed that IL-6 promoted the proliferation of PASMCs, but progesterone could reverse the adverse effect of IL-6. The protective effect was dependent on progesterone receptor (PGR). By interacting with signal transducer and activator of transcription 3 (STAT3), activated PGR could reduce the IL-6-induced nuclear translocation of STAT3 and prevent STAT3-chromatin binding in PASMCs, leading to the decreased transcription of downstream CCND1 and BCL2. Alternatively, progesterone slightly decreased the phosphorylation of pro-proliferative Erk1/2 and Akt kinases and upregulated the anti-proliferative pSmad1-Id1/2 axis in IL-6-incubated PASMCs.

CONCLUSIONS

Progesterone played a protective role on PASMCs in the context of IL-6, by blocking the functions of STAT3. Our findings might assist in explaining the clinical phenomenon of better prognosis for women with PAH.

"NOVEL MECHANISMS TARGETED BY DRUG TRIALS IN PULMONARY ARTERIAL HYPERTENSION"

Pulmonary arterial hypertension (PAH) is a rare disease associated with abnormally elevated pulmonary pressures and right heart failure resulting in high morbidity and mortality. While PAH prognosis has improved with the introduction of pulmonary vasodilators, disease progression remains a major problem. Given that available therapies are inadequate for preventing small vessel loss and obstruction, there is an active interest in identifying drugs capable of targeting angiogenesis and mechanisms involved in regulation of cell growth and fibrosis. Among the mechanisms linked to PAH pathogenesis, recent preclinical studies have identified promising compounds that are currently being tested in clinical trials. These drugs target seven of the major mechanisms associated with PAH pathogenesis: BMP signaling, tyrosine kinase receptors, estrogen metabolism, extracellular matrix, angiogenesis, epigenetics, and serotonin metabolism. In this review, we will discuss the preclinical studies that led to prioritization of these mechanisms and will discuss recently completed and ongoing phase 2/3 trials using novel interventions such as sotatercept, anastrozole, rodatristat ethyl, tyrosine kinase inhibitors, and endothelial progenitor cells among others. We anticipate that the next generation of compounds will build upon the success of the current standard of care and improve clinical outcomes and quality of life of patients afflicted with PAH.

Upregulation of Calcium Homeostasis Modulators in Contractile-To-Proliferative Phenotypical Transition of Pulmonary Arterial Smooth Muscle Cells

Excessive pulmonary artery (PA) smooth muscle cell (PASMC) proliferation and migration are implicated in the development of pathogenic pulmonary vascular remodeling characterized by concentric arterial wall thickening and arteriole muscularization in patients with pulmonary arterial hypertension (PAH). Pulmonary artery smooth muscle cell contractile-to-proliferative phenotypical transition is a process that promotes pulmonary vascular remodeling. A rise in cytosolic Ca2+ concentration [(Ca2+) cyt ] in PASMCs is a trigger for pulmonary vasoconstriction and a stimulus for pulmonary vascular remodeling. Here, we report that the calcium homeostasis modulator (CALHM), a Ca2+ (and ATP) channel that is allosterically regulated by voltage and extracellular Ca2+, is upregulated during the PASMC contractile-to-proliferative phenotypical transition. Protein expression of CALHM1/2 in primary cultured PASMCs in media containing serum and growth factors (proliferative PASMC) was significantly greater than in freshly isolated PA (contractile PASMC) from the same rat. Upregulated CALHM1/2 in proliferative PASMCs were associated with an increased ratio of pAKT/AKT and pmTOR/mTOR and an increased expression of the cell proliferation marker PCNA, whereas serum starvation and rapamycin significantly downregulated CALHM1/2. Furthermore, CALHM1/2 were upregulated in freshly isolated PA from rats with monocrotaline (MCT)-induced PH and in primary cultured PASMC from patients with PAH in comparison to normal controls. Intraperitoneal injection of CGP 37157 (0.6 mg/kg, q8H), a non-selective blocker of CALHM channels, partially reversed established experimental PH. These data suggest that CALHM upregulation is involved in PASMC contractile-to-proliferative phenotypical transition. Ca2+ influx through upregulated CALHM1/2 may play an important role in the transition of sustained vasoconstriction to excessive vascular remodeling in PAH or precapillary PH. Calcium homeostasis modulator could potentially be a target to develop novel therapies for PAH.