Genetic risk factors for portopulmonary hypertension in patients with advanced liver disease

Pulmonary Complications of Portal Hypertension

Portopulmonary hypertension (POPH), hepatopulmonary syndrome, and hepatic hydrothorax constitute significant complications of portal hypertension, with important implications for management and liver transplantation (LT) candidacy. POPH is characterized by obstruction and remodeling of the pulmonary resistance arterial bed. Hepatopulmonary syndrome is the most common pulmonary vascular disorder, characterized by intrapulmonary vascular dilatations causing impaired gas exchange. LT may improve prognosis in select patients with POPH. LT is the only effective treatment of hepatopulmonary syndrome. Hepatic hydrothorax is defined as transudative pleural fluid accumulation that is not explained by primary cardiopulmonary or pleural disease. LT is the definitive cure for hepatic hydrothorax.

Pulmonary arterial hypertension: Sex matters

Pulmonary arterial hypertension (PAH) is a complex disease of multifactorial origin. While registries have demonstrated that women are more susceptible to the disease, females with PAH have superior right ventricle (RV) function and a better prognosis than their male counterparts, a phenomenon referred to as the 'estrogen paradox'. Numerous pre-clinical studies have investigated the involvement of sex hormones in PAH pathobiology, often with conflicting results. However, recent advances suggest that abnormal estrogen synthesis, metabolism and signalling underpin the sexual dimorphism of this disease. Other sex hormones, such as progesterone, testosterone and dehydroepiandrosterone may also play a role. Several non-hormonal factor including sex chromosomes and epigenetics have also been implicated. Though the underlying pathophysiological mechanisms are complex, several compounds that modulate sex hormones levels and signalling are under investigation in PAH patients. Further elucidation of the estrogen paradox will set the stage for the identification of additional therapeutic targets for this disease.

Transcriptional profiles of pulmonary artery endothelial cells in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterized by endothelial cell (EC) dysfunction. There are no data from living patients to inform whether differential gene expression of pulmonary artery ECs (PAECs) can discern disease subtypes, progression and pathogenesis. We aimed to further validate our previously described method to propagate ECs from right heart catheter (RHC) balloon tips and to perform additional PAEC phenotyping. We performed bulk RNA sequencing of PAECs from RHC balloons. Using unsupervised dimensionality reduction and clustering we compared transcriptional signatures from PAH to controls and other forms of pulmonary hypertension. Select PAEC samples underwent single cell and population growth characterization and anoikis quantification. Fifty-four specimens were analyzed from 49 subjects. The transcriptome appeared stable over limited passages. Six genes involved in sex steroid signaling, metabolism, and oncogenesis were significantly upregulated in PAH subjects as compared to controls. Genes regulating BMP and Wnt signaling, oxidative stress and cellular metabolism were differentially expressed in PAH subjects. Changes in gene expression tracked with clinical events in PAH subjects with serial samples over time. Functional assays demonstrated enhanced replication competency and anoikis resistance. Our findings recapitulate fundamental biological processes of PAH and provide new evidence of a cancer-like phenotype in ECs from the central vasculature of PAH patients. This "cell biopsy" method may provide insight into patient and lung EC heterogeneity to advance precision medicine approaches in PAH.

Is pulmonary arterial hypertension associated with schistosomiasis distinct from pulmonary arterial hypertension associated with portal hypertension?

Pulmonary arterial hypertension associated with schistosomiasis (SchPAH) and pulmonary arterial hypertension associated with portal hypertension (PoPAH) are lung diseases that develop in the presence of liver diseases. However, mechanistic pathways by which the underlying liver conditions and other drivers contribute to the development and progression of pulmonary arterial hypertension (PAH) are unclear for both etiologies. In turn, these unknowns limit certainty of strategies to prevent, diagnose, and reverse the resultant PAH. Here we consider specific mechanisms that contribute to SchPAH and PoPAH, identifying those that may be shared and those that appear to be unique to each etiology, in the hope that this exploration will both highlight known causal drivers and identify knowledge gaps appropriate for future research. Overall, the key pathophysiologic differences that we identify between SchPAH and PoPAH suggest that they are not variants of a single condition.

Pulmonary Assessment of the Liver Transplant Recipient

Respiratory symptoms and hypoxemia can complicate chronic liver disease and portal hypertension. Various pulmonary disorders affecting the pleura, lung parenchyma, and pulmonary vasculature are seen in end-stage liver disease, complicating liver transplantation (LT). Approximately 8% of cirrhotic patients in an intensive care unit develop severe pulmonary problems. These disorders affect waiting list mortality and posttransplant outcomes. A thorough history, physical examination, and appropriate laboratory tests help diagnose and assess the severity to risk stratify pulmonary diseases before LT. Hepatopulmonary syndrome (HPS), portopulmonary hypertension (POPH), and hepatic hydrothorax (HH) are respiratory consequences specific to cirrhosis and portal hypertension. HPS is seen in 5-30% of cirrhosis cases and is characterized by impaired oxygenation due to intrapulmonary vascular dilatations and arteriovenous shunts. Severe HPS is an indication of LT. The majority of patients with HPS resolve their hypoxemia after LT. When pulmonary arterial hypertension occurs in patients with portal hypertension, it is called POPH. All other causes of pulmonary arterial hypertension should be ruled out before labeling as POPH. Since severe POPH (mean pulmonary artery pressure [mPAP] >50 mm Hg) is a relative contraindication for LT, it is crucial to screen for POPH before LT. Those with moderate POPH (mPAP >35 mm Hg), who improve with medical therapy, will benefit from LT. A transudative pleural effusion called hepatic hydrothorax (HH) is seen in 5-10% of people with cirrhosis. Refractory cases of HH benefit from LT. In recent years, increasing clinical expertise and advances in the medical field have resulted in better outcomes in patients with moderate to severe pulmonary disorders, who undergo LT.

Human liver single nuclear RNA sequencing implicates BMPR2, GDF15, arginine, and estrogen in portopulmonary hypertension

Portopulmonary hypertension (PoPH) is a type of pulmonary vascular disease due to portal hypertension that exhibits high morbidity and mortality. The mechanisms driving disease are unknown, and transcriptional characteristics unique to the PoPH liver remain unexplored. Here, we apply single nuclear RNA sequencing to compare cirrhotic livers from patients with and without PoPH. We identify characteristics unique to PoPH in cells surrounding the central hepatic vein, including increased growth differentiation factor signaling, enrichment of the arginine biosynthesis pathway, and differential expression of the bone morphogenic protein type II receptor and estrogen receptor type I genes. These results provide insight into the transcriptomic characteristics of the PoPH liver and mechanisms by which PoPH cellular dysfunction might contribute to pulmonary vascular remodeling.

Symptom-based portopulmonary hypertension screening questionnaire in Japanese patients with chronic liver disease

Background and Aim

As the exact prevalence of portopulmonary hypertension (PoPH) and the etiology of chronic liver disease (CLD) remain unknown, the present study aimed to clarify these points in Japanese patients with CLD using symptom-based questionnaire screening.

Methods

Patients with CLD were asked to complete an eight-item written questionnaire on pulmonary hypertension (PH) symptoms. If at least one item response was "yes," the patient was offered ultrasonic echocardiography (UCG). Patients identified as having an intermediate or high risk of PH by UCG were referred to a cardiologist for further evaluation, whereby a definitive diagnosis of PoPH was made using right heart catheterization (RHC) findings.

Results

A total of 1111 patients with CLD completed the survey. Of the 566 symptomatic patients with at least one question answered as "yes," approximately half agreed to undergo UCG (n = 267). Compared with asymptomatic patients, symptomatic patients were significantly older, predominantly female, and more frequently exhibited cirrhosis. Based on UCG findings, 228, 12, and 8 patients had a low, intermediate, or high risk for PH, respectively. Intermediate-/high-risk patients showed significantly more advanced disease progression status than low-risk patients. The frequencies of answer to the eight questions were comparable. Ultimately, three patients were diagnosed as having PoPH (1.1% of UCG cases), one with underlying hepatitis C virus (HCV) infection and two with primary biliary cholangitis (PBC).

Conclusion

This symptom-based PoPH screening study clarified the prevalence of PoPH in CLD patients according to a PH symptom questionnaire, UCG, and RHC. Patients with HCV and PBC may have a higher risk of PoPH.

Mechanisms of immunity in acutely decompensated cirrhosis and acute-on-chronic liver failure

The identification of systemic inflammation (SI) as a central player in the orchestration of acute-on-chronic liver failure (ACLF) has opened new avenues for the understanding of the pathophysiological mechanisms underlying this disease condition. ACLF, which develops in patients with acute decompensation of cirrhosis, is characterized by single or multiple organ failure and high risk of short-term (28-day) mortality. Its poor outcome is closely associated with the severity of the systemic inflammatory response. In this review, we describe the key features of SI in patients with acutely decompensated cirrhosis and ACLF, including the presence of a high blood white cell count and increased levels of inflammatory mediators in systemic circulation. We also discuss the main triggers (i.e. pathogen- and damage-associated molecular patterns), the cell effectors (i.e. neutrophils, monocytes and lymphocytes), the humoral mediators (acute phase proteins, cytokines, chemokines, growth factors and bioactive lipid mediators) and the factors that influence the systemic inflammatory response that drive organ failure and mortality in ACLF. The role of immunological exhaustion and/or immunoparalysis in the context of exacerbated inflammatory responses that predispose ACLF patients to secondary infections and re-escalation of end-organ dysfunction and mortality are also reviewed. Finally, several new potential immunogenic therapeutic targets are debated.

Risk factors for portopulmonary hypertension in patients with cirrhosis: a prospective, multicenter study

BACKGROUND

Tricuspid regurgitation pressure gradient (TRPG) measurement by echocardiography is recommended as the most objective examination to detect portopulmonary hypertension (PoPH). This study aimed to identify factors associated with a high TRPG in patients with cirrhosis and develop a scoring model for identifying patients who are most likely to benefit from echocardiography investigations.

RESULTS

A total of 486 patients who underwent echocardiography were randomly allocated to the derivation and validation sets at a ratio of 2:1. Of the patients, 51 (10.5%) had TRPG ≥ 35 mmHg. The median brain natriuretic peptide (BNP) was 39.5 pg/mL. Shortness of breath (SOB) was reported by 91 (18.7%) patients. In the derivation set, multivariate analysis identified female gender, shortness of breath, and BNP ≥ 48.9 pg/mL as independent factors for TRPG ≥ 35 mmHg. The risk score for predicting TRPG ≥ 35 mmHg was calculated as follows: - 3.596 + 1.250 × gender (female: 1, male: 0) + 1.093 × SOB (presence: 1, absence: 0) + 0.953 × BNP (≥ 48.9 pg/mL: 1, < 48.9 pg/mL: 0). The risk score yielded sensitivity of 66.7%, specificity of 75.3%, positive predictive value of 25.5%, negative predict value of 94.3%, and predictive accuracy of 74.4% for predicting TRPG ≥ 35 mmHg. These results were almost similar in the validation set, indicating the reproducibility and validity of the risk score.

CONCLUSIONS

This study clarified the characteristics of patients with suspected PoPH and developed a scoring model for identifying patients at high risk of PoPH, which may be used in selecting patients that may benefit from echocardiography.

Struggling Between Liver Transplantation and Portopulmonary Hypertension

Portopulmonary hypertension (PoPH) is a progressive, ultimately fatal cardiopulmonary disease that occurs exclusively in patients with underlying portal hypertensive liver disease. PoPH outcomes are driven by both the severity of underlying liver disease and the degree of cardiac adaptation to elevated pulmonary pressures. The mainstay of treatment in PoPH is targeted pulmonary vascular therapy. Liver transplantation (LT) can be beneficial in some patients, but is associated with considerable risks in the PoPH population, and outcomes are variable. The optimal management strategy for PoPH, LT, or medical therapy alone, is unclear, and further research is needed to help guide clinical decision-making.

Gender Differences in Genotypic Distribution of Endothelin-1 Gene and Endothelin receptor A gene in Pulmonary Hypertension associated with Rheumatic Mitral Valve Disease

Introduction

The female gender is a risk factor for idiopathic pulmonary arterial hypertension. However, it is unknown whether females with rheumatic mitral valve disease are more predisposed to develop pulmonary hypertension compared to males.

Aim

We aimed to investigate whether there was a difference in genotypic distribution of endothelin-1 (ET-1) and endothelin receptor A (ET_A) genes between female and male patients of pulmonary hypertension associated with rheumatic mitral valve disease (PH-MVD).

Methods

We compared prevalence of ET-1 gene (Lys198Asn) and ET_A gene (His323His) polymorphisms according to gender in 123 PH-MVD subjects and 123 healthy controls.

Results

The presence of mutant Asn/Asn and either mutant Asn/Asn or heterozygous Lys/Asn genotypes of Lys198Asn polymorphism when compared to Lys/Lys in females showed significant association with higher risk (odds ratio [OR] 4.5; p =0.007 and OR 2.39; p =0.02, respectively). The presence of heterozygous C/T and either mutant T/T or heterozygous C/T genotypes of His323His polymorphism when compared to wild C/C genotype in females showed a significant association with higher risk (OR 1.96; p =0.047 and OR 2.26; p =0.01, respectively). No significant difference was seen in genotypic frequencies in males between PH-MVD subjects and controls. Logistic regression analysis showed that mutant genotype Asn/Asn (p =0.007) and heterozygous genotype Lys/Asn of Lys198Asn polymorphism (p =0.018) were independent predictors of development of PH in females.

Conclusions

ET-1 and ET_A gene polymorphisms were more prevalent in females than males in PH-MVD signifying that females with rheumatic heart disease may be more susceptible to develop PH.

Sex Differences in Pulmonary Hypertension

Pulmonary hypertension (PH) includes multiple diseases that share as common characteristic an elevated pulmonary artery pressure and right ventricular involvement. Sex differences are observed in practically all causes of PH. The most studied type is pulmonary arterial hypertension (PAH) which presents a gender bias regarding its prevalence, prognosis, and response to treatment. Although this disease is more frequent in women, once affected they present a better prognosis compared to men. Even if estrogens seem to be the key to understand these differences, animal models have shown contradictory results leading to the birth of the estrogen paradox. In this review we will summarize the evidence regarding sex differences in experimental animal models and, very specially, in patients suffering from PAH or PH from other etiologies.

Porto-pulmonary arterial hypertension: Translation of pathophysiological concepts to the bedside

Porto-pulmonary arterial hypertension (PoPAH) is a form of pulmonary arterial hypertension (PAH) that affects patients with cirrhosis, and - to a lesser extent - patients with non-cirrhotic liver diseases. Compared with other forms of PAH, PoPAH is more prevalent in male, in older subjects, and is characterized by lower mean pulmonary arterial pressure (mPAP) and lower pulmonary vascular resistance (PVR) with higher cardiac output. Despite more favorable hemodynamics and functional class, patients with PoPAH have a significantly worse survival than patients with other forms of PAH, likely because of liver-related events and therapeutic barriers to PAH-specific therapy. Furthermore, here cardiopulmonary and hepatic complications may affect treatment efficacy. These patients have been excluded from most randomized clinical trials testing PAH-specific treatments. To date, there is only one study investigating efficacy, safety, tolerability and pharmacokinetics of PAH-specific therapy in patients with PoPAH in a randomized placebo-controlled setting. In this trial the use of the endothelin-1 receptor antagonist macitentan showed clear hemodynamic benefit without safety concerns. However, the drug effects on functional capacity and mortality remain unclear. Here we review the current knowledge on the pathophysiology and management of PoPAH and report a case vignette of a patient with PoPAH due to hepatorenal polycystic disease.

Portopulmonary Hypertension: A Review of the Current Literature

Portopulmonary hypertension is defined as the development of pulmonary arterial hypertension in the setting of portal hypertension with or without liver cirrhosis. Portal hypertension-associated haemodynamic changes, including hyperdynamic state, portosystemic shunts and splanchnic vasodilation, induce significant alterations in pulmonary vascular bed and play a pivotal role in the pathogenesis of the disease. If left untreated, portopulmonary hypertension results in progressive right heart failure, with a poor prognosis. Although Doppler echocardiography is the best initial screening tool for symptomatic patients and liver transplantation candidates, right heart catheterisation remains the gold standard for the diagnosis of the disease. Severe portopulmonary hypertension exerts a prohibitive risk to liver transplantation by conferring an elevated perioperative mortality risk. It is important for haemodynamic parameters to correspond with non-severe portopulmonary hypertension before patients can proceed with the liver transplantation. Small uncontrolled studies and a recent randomised controlled trial have reported promising results with vasodilatory therapies in clinical and haemodynamic improvement of patients, allowing a proportion of patients to undergo liver transplantation. In this review, the epidemiology, pathogenesis, diagnostic approach and management of portopulmonary hypertension are discussed. We also highlight fields of ongoing investigation pertinent to risk stratification and optimal patient selection to maximise long-term benefit from currently available treatments.

Screening for portopulmonary hypertension using computed tomography-based measurements of the main pulmonary artery and ascending aorta diameters in patients with portal hypertension

AIM

This study aimed to demonstrate the feasibility of identifying candidates of portopulmonary hypertension (PoPH) from general portal hypertension patients based on chest computed tomography (CT) results.

METHODS

One hundred and thirty patients with portal hypertension who had undergone interventional radiology therapies at our hospital between August 2011 and July 2021 were included, and preoperative clinical data were collected. Suspicious PoPH was defined as main pulmonary artery diameter (mPA-D) ≥ 29 mm or the ratio of mPA-D to ascending aorta diameter (mPA-D/aAo-D) ≥ 1.0, and probable PoPH as mPA-D ≥ 33 mm based on the chest CT. Prevalence of suspicious and probable PoPH was evaluated, and the differences in clinical characteristics of each population were compared.

RESULTS

Overall, 29 (22.3%) and 5 (3.8%) patients were categorized as suspicious and probable PoPH, respectively. Univariate analyses revealed that female sex, higher shortest diameter of inferior vena cava, presence of portosystemic shunts ≥ 5 mm, and lower blood urea nitrogen levels were significantly associated with suspicious PoPH (p < 0.05). Multivariate analyses identified all four factors as significantly independent determinants of suspicious PoPH (p < 0.05). In addition, among the population of suspicious PoPH, there were significant differences in seven parameters, including total bilirubin levels and spleen volume between patients with and without probable PoPH (p < 0.05). However, no significant independent indicators of probable PoPH were found.

CONCLUSIONS

CT-based measurements of mPA-D and mPA-D/aAo-D have the potential to screen patients with suspicious PoPH in clinical practice focused on portal hypertension.

Sex and gender in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare disease characterised by pulmonary vascular remodelling and elevated pulmonary pressure, which eventually leads to right heart failure and death. Registries worldwide have noted a female predominance of the disease, spurring particular interest in hormonal involvement in the disease pathobiology. Several experimental models have shown both protective and deleterious effects of oestrogens, suggesting that complex mechanisms participate in PAH pathogenesis. In fact, oestrogen metabolites as well as receptors and enzymes implicated in oestrogen signalling pathways and associated conditions such as BMPR2 mutation contribute to PAH penetrance more specifically in women. Conversely, females have better right ventricular function, translating to a better prognosis. Along with right ventricular adaptation, women tend to respond to PAH treatment differently from men. As some young women suffer from PAH, contraception is of particular importance, considering that pregnancy in patients with PAH is strongly discouraged due to high risk of death. When contraception measures fail, pregnant women need a multidisciplinary team-based approach. This article aims to review epidemiology, mechanisms underlying the higher female predominance, but better prognosis and the intricacies in management of women affected by PAH.

Hepatopulmonary Syndrome and Portopulmonary Hypertension: Pulmonary Vascular Complications of Liver Disease

Pulmonary vascular disease is a frequent complication of chronic liver disease and portal hypertension, affecting up to 30% of patients. There are two distinct pulmonary vascular complications of liver disease: hepatopulmonary syndrome (HPS) and portopulmonary hypertension (POPH). HPS affects 25% of patients with chronic liver disease and is characterized by intrapulmonary vasodilatation and abnormal arterial oxygenation. HPS negatively impacts quality of life and is associated with a 2-fold increased risk of death compared to controls with liver disease without HPS. Angiogenesis, endothelin-1 mediated endothelial dysfunction, monocyte influx, and alveolar type 2 cell dysfunction seem to play important roles in disease pathogenesis but there are currently no effective medical therapies. Fortunately, HPS resolves following liver transplant (LT) with improvements in hypoxemia. POPH is a subtype of pulmonary arterial hypertension (PAH) characterized by an elevated mean pulmonary arterial pressure and pulmonary vascular resistance in the setting of normal left-sided filling pressures. POPH affects 5% to 6% of patients with chronic liver disease. Although the pathogenesis has not been fully elucidated, endothelial dysfunction, inflammation, and estrogen signaling have been identified as key pathways involved in disease pathogenesis. POPH is typically treated with PAH targeted therapy and may also improve with liver transplantation in selected patients. This article highlights what is currently known regarding the diagnosis, management, pathobiology, and outcomes of HPS and POPH. Ongoing research is needed to improve understanding of the pathophysiology and outcomes of these distinct and often misunderstood pulmonary vascular complications of liver disease. © 2021 American Physiological Society. Compr Physiol 11:1-22, 2021.

Prevalence and Associated Factors of Portopulmonary Hypertension in Patients with Portal Hypertension: A Case-Control Study

Background and Aims

There are few studies on the prevalence and clinical characteristics of portopulmonary hypertension (POPH) in patients with portal hypertension. In addition, invasive right heart catheterization further limits the clinical diagnosis of POPH patients.

Methods

From January 2018 to December 2019, 1004 patients with portal hypertension were treated in the Department of Hepatology, the First Hospital of Jilin University. Based on the inclusion and exclusion criteria, 188 patients with portal hypertension were finally included. We collected complete clinical data, laboratory examinations, and imaging examinations. Patients were divided into a POPH group and a non-POPH group based on echocardiographic results. We calculated the prevalence of POPH in patients with portal hypertension. The differences in clinical characteristics of the two groups of patients were compared.

Results

The prevalence of POPH in patients with portal hypertension was 2.8%. Among the 188 patients with portal hypertension with fingertip oxygen saturation < 95% at rest, 28 patients had POPH (12 males and 16 females), with an average age of 63 ± 8, and 160 patients did not have POPH (110 males, 50 women), with an average age of 59 ± 11. The proportion of women in the POPH group (P < 0.01) and patients without liver cancer (P = 0.044) was high. Compared to patients without POPH, patients with POPH had lower hemoglobin (related to the severity of anemia, P < 0.01), higher creatinine (P < 0.05), and lower partial pressure of oxygen and carbon dioxide (P < 0.05). Patients with POPH had a higher incidence of atrial enlargement, ventricular enlargement, mitral valve regurgitation, tricuspid regurgitation, pulmonary artery widening, pericardial effusion, and aortic regurgitation than those without POPH. The risk of POPH did not increase with the aggravation of the Child-Pugh classification.

Conclusion

The prevalence of POPH in patients with portal hypertension is 2.8%. The proportion of women and nonliver cancer in POPH patients was higher than that in non-POPH patients. In addition, the POPH group had higher creatinine and lower hemoglobin, and echocardiography showed that POPH patients had more cardiac structural changes. In patients with portal hypertension, the risk in patients with POPH has nothing to do with the Child-Pugh classification and MELD score.

Roles of Genetic Predisposition in the Sex Bias of Pulmonary Pathophysiology, as a Function of Estrogens : Sex Matters in the Prevalence of Lung Diseases

In addition to studies focused on estrogen mediation of sex-different regulation of systemic circulations, there is now increasing clinical relevance and research interests in the pulmonary circulation, in terms of sex differences in the morbidity and mortality of lung diseases such as inherent-, allergic- and inflammatory-based events. Thus, female predisposition to pulmonary artery hypertension (PAH) is an inevitable topic. To better understand the nature of sexual differentiation in the pulmonary circulation, and how heritable factors, in vivo- and/or in vitro-altered estrogen circumstances and changes in the live environment work in concert to discern the sex bias, this chapter reviews pulmonary events characterized by sex-different features, concomitant with exploration of how alterations of genetic expression and estrogen metabolisms trigger the female-predominant pathological signaling. We address the following: PAH (Sect.7.2) is characterized as an estrogenic promotion of its incidence (Sect. 7.2.2), as a function of specific germline mutations, and as an estrogen-elicited protection of its prognosis (Sect.7.2.1). More detail is provided to introduce a less recognized gene of Ephx2 that encodes soluble epoxide hydrolase (sEH) to degrade epoxyeicosatrienic acids (EETs). As a susceptible target of estrogen, Ephx2/sEH expression is downregulated by an estrogen-dependent epigenetic mechanism. Increases in pulmonary EETs then evoke a potentiation of PAH generation, but mitigation of its progression, a phenomenon similar to the estrogen-paradox regulation of PAH. Additionally, the female susceptibility to chronic obstructive pulmonary diseases (Sect. 7.3) and asthma (Sect.7.4), but less preference to COVID-19 (Sect. 7.5), and roles of estrogen in their pathogeneses are briefly discussed.

Protocol: Prospective observational study investigating the prevalence and clinical outcome of portopulmonary hypertension in Japanese patients with chronic liver disease

BACKGROUND

Portopulmonary hypertension (PoPH) is a subtype of the pulmonary arterial hypertension (PAH) associated with portal hypertension. There is a dissociation between the proportion of PoPH in PAH and that of PoPH in patients with liver cirrhosis, suggesting PoPH underdiagnosis and an incomplete understanding of this entity in the clinical setting. Specifically, real-world data in Japan is largely unknown as compared with in Europe and the United States. The present study aims to elucidate the prevalence and etiology of PoPH in Japanese patients with chronic liver disease.

METHODS AND DESIGN

In this prospective, single-center, observational investigation of PoPH patients with chronic liver disease, a targeted 2,500 Japanese adult patients regularly visiting Shinshu University Hospital in Matsumoto, Japan, for chronic liver disease will complete a standardized questionnaire on the presence of PoPH symptoms. If the respondent has signs of possible PoPH, ultrasound echocardiography (UCG) will be performed as a primary screening. In the case that UCG findings indicate pulmonary hypertension, the patient will be referred to a cardiologist for further evaluation, whereby a definitive diagnosis PoPH can be made. PoPH prevalence and etiology will be investigated at the time of diagnosis. Afterwards, patients with PoPH will be followed for five years for determination of survival rate.

DISCUSSION

This study will reveal the prevalence, etiology, and 5-year survival rate of PoPH in Japanese patients with chronic liver disease.

TRIAL REGISTRATION

This study is being performed at Shinshu University following registration as UMIN 000042287 on October 29, 2020.

Identifying Potential Mutations Responsible for Cases of Pulmonary Arterial Hypertension

Pulmonary Arterial Hypertension (PAH) is a progressive and devastating disease for which there is an escalating body of genetic and related pathophysiological information on disease pathobiology. Nevertheless, the success to date in identifying susceptibility genes, genetic variants and epigenetic processes has been limited due to PAH clinical multi-faceted variations. A number of germline gene candidates have been proposed but demonstrating consistently the association with PAH has been problematic, at least partly due to the reduced penetrance and variable expressivity. Although the data for bone morphogenetic protein receptor type 2 (BMPR2) and related genes remains undoubtedly the most extensive, recent advanced gene sequencing technologies have facilitated the discovery of further gene candidates with mutations among those with and without familial forms of PAH. An in depth understanding of the multitude of biologic variations associated with PAH may provide novel opportunities for therapeutic intervention in the coming years. This knowledge will irrevocably provide the opportunity for improved patient and family counseling as well as improved PAH diagnosis, risk assessment, and personalized treatment.

17β-Estradiol and estrogen receptor α protect right ventricular function in pulmonary hypertension via BMPR2 and apelin

Women with pulmonary arterial hypertension (PAH) exhibit better right ventricular (RV) function and survival than men; however, the underlying mechanisms are unknown. We hypothesized that 17β-estradiol (E2), through estrogen receptor α (ER-α), attenuates PAH-induced RV failure (RVF) by upregulating the procontractile and prosurvival peptide apelin via a BMPR2-dependent mechanism. We found that ER-α and apelin expression were decreased in RV homogenates from patients with RVF and from rats with maladaptive (but not adaptive) RV remodeling. RV cardiomyocyte apelin abundance increased in vivo or in vitro after treatment with E2 or ER-α agonist. Studies employing ER-α-null or ER-β-null mice, ER-α loss-of-function mutant rats, or siRNA demonstrated that ER-α is necessary for E2 to upregulate RV apelin. E2 and ER-α increased BMPR2 in pulmonary hypertension RVs and in isolated RV cardiomyocytes, associated with ER-α binding to the Bmpr2 promoter. BMPR2 is required for E2-mediated increases in apelin abundance, and both BMPR2 and apelin are necessary for E2 to exert RV-protective effects. E2 or ER-α agonist rescued monocrotaline pulmonary hypertension and restored RV apelin and BMPR2. We identified what we believe to be a novel cardioprotective E2/ER-α/BMPR2/apelin axis in the RV. Harnessing this axis may lead to novel RV-targeted therapies for PAH patients of either sex.

Sex Differences in Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) occurs in women more than men whereas survival in men is worse than in women. In recent years, much research has been carried out to understand these sex differences in PAH. This article discusses clinical and preclinical studies that have investigated the influences of sex, serotonin, obesity, estrogen, estrogen synthesis, and estrogen metabolism on bone morphogenetic protein receptor type II signaling, the pulmonary circulation and right ventricle in both heritable and idiopathic pulmonary hypertension.

Estrogen Signaling and Portopulmonary Hypertension: The Pulmonary Vascular Complications of Liver Disease Study (PVCLD2)

BACKGROUND AND AIMS

Portopulmonary hypertension (POPH) was previously associated with a single-nucleotide polymorphism (SNP) rs7175922 in aromatase (cytochrome P450 family 19 subfamily A member 1 [CYP19A1]). We sought to determine whether genetic variants and metabolites in the estrogen signaling pathway are associated with POPH.

APPROACH AND RESULTS

We performed a multicenter case-control study. POPH patients had mean pulmonary artery pressure >25 mm Hg, pulmonary vascular resistance >240 dyn-sec/cm-5 , and pulmonary artery wedge pressure ≤15 mm Hg without another cause of pulmonary hypertension. Controls had advanced liver disease, right ventricular (RV) systolic pressure <40 mm Hg, and normal RV function by echocardiography. We genotyped three SNPs in CYP19A1 and CYP1B1 using TaqMan and imputed SNPs in estrogen receptor 1 using genome-wide markers. Estrogen metabolites were measured in blood and urine samples. There were 37 patients with POPH and 290 controls. Mean age was 57 years, and 36% were female. The risk allele A in rs7175922 (CYP19A1) was significantly associated with higher levels of estradiol (P = 0.02) and an increased risk of POPH (odds ratio [OR], 2.36; 95% confidence interval [CI], 1.12-4.91; P = 0.02) whereas other SNPs were not. Lower urinary 2-hydroxyestrogen/16-α-hydroxyestrone (OR per 1-ln decrease = 2.04; 95% CI, 1.16-3.57; P = 0.01), lower plasma levels of dehydroepiandrosterone-sulfate (OR per 1-ln decrease = 2.38; 95% CI, 1.56-3.85; P < 0.001), and higher plasma levels of 16-α-hydroxyestradiol (OR per 1-ln increase = 2.16; 95% CI, 1.61-2.98; P < 0.001) were associated with POPH.

CONCLUSIONS

Genetic variation in aromatase and changes in estrogen metabolites were associated with POPH.

Genetic Variants of ANGPT1, CD39, FGF2 and MMP9 Linked to Clinical Outcome of Bevacizumab Plus Chemotherapy for Metastatic Colorectal Cancer

Angiogenesis pathway genes show substantial genetic variability causing inter-individual differences in responses to anti-angiogenic drugs. We examined 20 single nucleotide polymorphisms (SNPs) in 13 of these genes to predict tumour response and clinical outcome measured as progression free survival (PFS) and overall survival (OS) in 57 patients with metastatic colorectal cancer (mCRC) given bevacizumab plus chemotherapy. SNPs were detected (iPLEX® Assay) in genomic DNA extracted from formalin-fixed paraffin-embedded tumour specimens. The variant allele CD39 rs11188513 was associated with a good tumour response (p = 0.024). Patients homozygous for the wild-type allele FGF2 rs1960669 showed a median PFS of 10.95 months versus 5.44 months for those with at least one variant allele-A (HR 3.30; 95% CI: 1.52–7.14; p = 0.001). Patients homozygous for wild-type MMP9 rs2236416 and rs2274755 showed a median PFS of 9.48 months versus 6 and 6.62 months, respectively, for those with at least one variant allele (p = 0.022, p = 0.043, respectively). OS was also lengthened to 30.92 months (p = 0.034) in carriers of wild-type ANGPT1 rs2445365 versus 22.07 months for those carrying at least one variant allele-A. These gene variants were able to predict clinical outcome and tumour response in mCRC patients given bevacizumab-based therapy.

A Case of Hypopituitarism Complicated by Non-Alcoholic Steatohepatitis and Severe Pulmonary Hypertension

BACKGROUND Pulmonary arterial hypertension (PAH), which is caused by increased pulmonary artery pressure, results in right-heart failure and presents with shortness of breath, chest pain, and syncope. PAH has idiopathic, heritable, and drug/toxin causes and is accompanied by other conditions, including connective tissue disease, congenital heart disease, and portal hypertension. Rarely, portal hypertension causes a type of PAH called portopulmonary hypertension (POPH). Portal hypertension can be triggered by liver cirrhosis, which can result from non-alcoholic steatohepatitis (NASH), a metabolic syndrome caused by hypopituitarism. Although an association between hypopituitarism and POPH has been suggested, few reports have described this relationship. CASE REPORT A 43-year-old woman with hypopituitarism received hormone replacement therapy after partial hypothalamic resection at age 4 years. At age 32 years, she developed liver cirrhosis from NASH due to adult growth hormone (GH) deficiency. Despite restarting GH replacement therapy, she refused the required GH doses for economic reasons. She was hospitalized with abdominal pain and dyspnea and was found to have severe POPH. She received PAH-specific therapies, including endothelin receptor antagonist and prostacyclin analog. Pulmonary hypertension improved on day 3 of hospitalization while the cardiac index increased gradually. On day 12, her respiratory status rapidly worsened and percutaneous cardiopulmonary support was applied. On day 18, she died of multiple organ failure and disseminated intravascular coagulation despite intensive care management. CONCLUSIONS Severe PAH, particularly POPH, remains incurable despite the use of PAH-specific therapies and intensive care management. For hypopituitarism patients, careful observation, including of the cardiopulmonary system, can improve the prognosis after completing hormone replacement therapy.

Portopulmonary Hypertension: From Bench to Bedside

Portopulmonary hypertension (PoPH) is defined as pulmonary arterial hypertension (PAH) associated with portal hypertension and is a subset of Group 1 pulmonary hypertension (PH). PoPH is a cause of significant morbidity and mortality in patients with portal hypertension with or without liver disease. Significant strides in elucidating the pathogenesis, effective screening algorithms, accurate diagnoses, and treatment options have been made in past 20 years. Survival of PoPH has remained poor compared to IPAH and other forms of PAH. Recently, the first randomized controlled trial was done in this patient population and showed promising results with PAH specific therapy. Despite positive effects on hemodynamics and functional outcomes, it is unclear whether PAH specific therapy has a beneficial effect on long term survival or transplant outcomes. In this review, we will discuss the epidemiology, pathophysiology, clinical and hemodynamic characteristics of PoPH. Additionally, this review will highlight the lacunae in our current management strategy, challenges faced and will provide direction to potentially useful futuristic management strategies.

Prevalence and characteristics of portopulmonary hypertension in cirrhotic patients who underwent both hepatic vein and pulmonary artery catheterization

Portopulmonary hypertension (PoPH) is a well-known complication of liver cirrhosis. The aim of this study was to clarify the pulmonary hemodynamics and the prevalence and characteristics of PoPH in patients with portal hypertension.

METHODS

The subjects were 335 patients with portal hypertension diagnosed by hepatic vein pressure gradient (HVPG). Among them, 186 patients received measurements of pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP) and pulmonary vascular resistance (PVR). PoPH was diagnosed by PAP >20 mmHg, PVR ≥3 Wood units (WU) and PAWP ≤15 mmHg.

RESULTS

The Child-Pugh classification was class A in 53, B in 92 and C in 41 patients. Median (range) values of HVPG, PAP, PVR and PAWP were 18.4 (5.5-39.0) mmHg, 12.9 (6.6-40.8) mmHg, 0.8 (0.1-4.5) WU and 7.5 (2.2-15.4) mmHg, respectively. Of six patients with PAP >20 mmHg, four had autoimmune hepatitis or primary biliary cholangitis, with the prevalence being significantly higher than that in patients with PAP ≤20 mmHg. Meanwhile, no significant difference was noted in the hepatic functional reserve or HVPG between patients with PAP >20 mmHg and ≤20 mmHg. Only two patients met the diagnostic criteria of PoPH and both patients were Child-Pugh B. The Child-Pugh score and HVPG were not associated with PoPH.

CONCLUSIONS

Our study demonstrated that only two patients were complicated by PoPH. High PAP values were noted in patients with primary biliary cholangitis or autoimmune hepatitis. However, the presence of PoPH and high PAP were not associated with the degree of hepatic functional reserve or HVPG.

Incidence and long-term outcomes of pregnant women complicated with pulmonary arterial hypertension during different pregnancies: A prospective cohort study from China

BACKGROUND

Pulmonary arterial hypertension(PAH) in pregnancy is a risk factor for maternal and infant death. Our study was to explore the characteristics and outcomes of pregnant women complicated with PAH during different pregnancies.

METHOD

Clinical data were compared among women complicated with PAH in the first and second pregnancy between 2012 and 2018.

RESULTS

A total of 156 patients with newly diagnosed PAH during pregnancy were enrolled. Among them, 108 (26.9 ± 3.5 years old) and 48 (30.8 ± 4.8 years old) were diagnosed PAH during their first and second pregnancy, respectively. And the incidence rates were 5.7‰ and 6.6‰ (p = 0.448). Pulmonary artery systolic pressure(sPAP)(55 ± 19 vs. 71 ± 27 mmHg, p = 0.001), NYHA functional class III-IV patients (10.2% vs. 35.4%, p < 0.001) and incidence of heart failure (5.6% vs. 18.8%, p = 0.01) were higher in the second pregnancy group than those in the first pregnancy group. Multivariate linear regression revealed that parity and time of symptom onset were independent factors of sPAP during pregnancy (p < 0.001). Multivariate logistic regression revealed that sPAP (OR = 1.045, 95% CI, 1.021-1.069) was a risk factor for perinatal heart failure, with a cut-off value of 56 mmHg (Youden index 0.586, sensitivity 93%, specificity 65%). The cumulative death rate in the subsequent 48 months (IQR: 29 to 71) were 2.8% and 10.4% (p = 0.033) in the first and second pregnancy group, respectively.

CONCLUSIONS

Incidence of PAH in pregnancy tends to increase with increased parity. PAH identified in during the second pregnancy were associated with more severe disease and poorer long term outcomes.

Sex Differences in Portopulmonary Hypertension

BACKGROUND

Portopulmonary hypertension (POPH), pulmonary arterial hypertension that develops in the setting of portal hypertension, can lead to right-sided heart failure and death. Being female is a known risk factor for POPH, but little is known about the effect of sex on clinical manifestations, hemodynamics, treatment response, and survival.

RESEARCH QUESTION

We sought to characterize sex differences in clinical characteristics, pulmonary hemodynamics, treatment response, and survival in patients with POPH.

STUDY DESIGN AND METHODS

We performed a retrospective cohort study of adult candidates for liver transplant (LT) who had POPH within the Organ Procurement and Transplantation Network database. Females and males were compared. Multivariate regression was performed to assess the association between sex and pulmonary vascular resistance (PVR) and survival. Patients were also stratified by age (50 years) to determine how age modifies the relationship between sex and hemodynamics and survival.

RESULTS

We included 190 adults (103 male, 87 female). Compared with men, women had a lower model for end-stage liver disease (MELD) score (12.1± 4.2 vs 13.8 ± 4.9; P = .01) and were more likely to have autoimmune liver disease. Women had a higher baseline PVR (610.6 ± 366.6 vs 461.0 ± 185.3 dynes-s-cm^-5; P < .001) and posttreatment PVR (244.6 ± 119.5 vs 202.0 ± 87.7 dynes-s-cm^-5; P = .008) and a greater treatment response (ΔPVR) (-359.3 ± 381.9 vs -260.2 ± 177.3 dynes-s-cm^-5; P = .03). In multivariate analysis, female sex (or gender) remained associated with a higher baseline PVR (P = .008). Women and men had overall similar survival (P > .05). When patients were stratified by age, being female was independently associated with worse waiting list survival after adjusting for MELD and PVR in younger patients (HR, 6.61; 95% CI, 1.25-35.08; P = .03) but not in older patients.

INTERPRETATION

Compared with male candidates, female candidates for LT who had POPH had a higher PVR and lower MELD score and were more likely to have autoimmune liver disease. Women and men had similar overall survival, but female sex (or gender) was associated with worse survival in younger patients.

Five variants of the superoxide dismutase genes in Turkish women with polycystic ovary syndrome

INTRODUCTION

Polycystic ovary syndrome (PCOS) is one of the most common endocrine-reproductive-metabolic disorders of women at reproductive age. Many investigations have revealed that reactive oxygen species (ROS) level is significantly increased in patients with PCOS compared to healthy women.

OBJECT

The goal of the current study is to investigate the association between superoxide dismutase (SOD) variants and the risk of PCOS among Turkish women.

METHOD AND SUBJECTS

Three hundred twelve voluntary premenopausal women (148 healthy controls and 164 patients with PCOS) 18-45 years of age were include the study. All volunteers underwent physical examination and biochemical hormones evaluation. Five selected variants in SOD1 (+35 A/C (rs2234694) and SOD2 (-102 C > T, 3'UTRT > A (rs2842980), 3'UTRA > G (rs5746136), and Ala16ValC > T (rs4880) were analysed by using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method.

RESULT

3'UTRA > G and Ala16ValC > T variants showed significant differences between study groups. In the additive model of rs5746136 variant having AG and GG genotype increased the PCOS risk 2-fold (OR: 1.7, 95% CI: 1.08-2.77, p = 0.003) and 5-fold (OR: 5, 95% CI: 1.7-14.2,p = 0.003) compared to AA genotype, respectively. To have a GG + AG genotype increased the PCOS risk 2-fold (OR: 2.95% Cl: 1.2-3.1, p = 0.003) compared to AA genotype in "G" dominant model. In case of the "G" recessive model, having a GG genotype increased the PCOS risk 4-fold (OR: 3.8, 95% CI: 1.3-10.4, p = 0.01) compared to AA + AG genotype. The TT genotype of rs4880 showed almost 2-fold (OR: 1.8, 95% CI: 1.12-3.0) increased PCOS risk in the "T" recessive model.

CONCLUSION

It is quite likely that the variants which result in decreased function in the antioxidant defence mechanism related genes contribute to PCOS aetiology with inhibiting/reducing of ROS elimination.

Obesity, estrogens and adipose tissue dysfunction - implications for pulmonary arterial hypertension

Obesity is a prevalent global public health issue characterized by excess body fat. Adipose tissue is now recognized as an important endocrine organ releasing an abundance of bioactive adipokines including, but not limited to, leptin, adiponectin and resistin. Obesity is a common comorbidity amongst pulmonary arterial hypertension patients, with 30% to 40% reported as obese, independent of other comorbidities associated with pulmonary arterial hypertension (e.g. obstructive sleep apnoea). An 'obesity paradox' has been observed, where obesity has been associated with subclinical right ventricular dysfunction but paradoxically may confer a protective effect on right ventricular function once pulmonary hypertension develops. Obesity and pulmonary arterial hypertension share multiple pathophysiological mechanisms including inflammation, oxidative stress, elevated leptin (proinflammatory) and reduced adiponectin (anti-inflammatory). The female prevalence of pulmonary arterial hypertension has instigated the hypothesis that estrogens may play a causative role in its development. Adipose tissue, a major site for storage and metabolism of sex steroids, is the primary source of estrogens and circulating estrogens levels which are elevated in postmenopausal women and men with pulmonary arterial hypertension. This review discusses the functions of adipose tissue in both health and obesity and the links between obesity and pulmonary arterial hypertension. Shared pathophysiological mechanisms and the contribution of specific fat depots, metabolic and sex-dependent differences are discussed.

Pathophysiological-based treatments of complications of cirrhosis

Detailed knowledge and understanding of the pathophysiological mechanisms and changes in hepatic and splanchnic function leading to the development of haemodynamic changes and portal hypertension in patients with cirrhosis are essential since it guides the search for targets to ameliorate liver-related abnormalities. Recent research has focused on the gut-liver axis, changes in intestinal permeability, translocation of bacterial products, and inflammation as important drivers of haemodynamic alterations and thereby targets for treatment. Additionally, treatment strategies should focus on microbiotic modulation, antiangiogenics, anti-inflammatory strategies, and modulation of bile acid metabolism. This paper aims to review contemporary pathophysiological-based treatment principles of the major complications of cirrhosis and portal hypertension and future targets for treatment.

Estradiol Metabolism: Crossroads in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a debilitating and progressive disease that predominantly develops in women. Over the past 15 years, cumulating evidence has pointed toward dysregulated metabolism of sex hormones in animal models and patients with PAH. 17β-estradiol (E2) is metabolized at positions C2, C4, and C16, which leads to the formation of metabolites with different biological/estrogenic activity. Since the first report that 2-methoxyestradiol, a major non-estrogenic metabolite of E2, attenuates the development and progression of experimental pulmonary hypertension (PH), it has become increasingly clear that E2, E2 precursors, and E2 metabolites exhibit both protective and detrimental effects in PH. Furthermore, both experimental and clinical data suggest that E2 has divergent effects in the pulmonary vasculature versus right ventricle (estrogen paradox in PAH). The estrogen paradox is of significant clinical relevance for understanding the development, progression, and prognosis of PAH. This review updates experimental and clinical findings and provides insights into: (1) the potential impacts that pathways of estradiol metabolism (EMet) may have in PAH; (2) the beneficial and adverse effects of estrogens and their precursors/metabolites in experimental PH and human PAH; (3) the co-morbidities and pathological conditions that may alter EMet and influence the development/progression of PAH; (4) the relevance of the intracrinology of sex hormones to vascular remodeling in PAH; and (5) the advantages/disadvantages of different approaches to modulate EMet in PAH. Finally, we propose the three-tier-estrogen effects in PAH concept, which may offer reconciliation of the opposing effects of E2 in PAH and may provide a better understanding of the complex mechanisms by which EMet affects the pulmonary circulation–right ventricular interaction in PAH.

Sex, Gender, and Sex Hormones in Pulmonary Hypertension and Right Ventricular Failure

Pulmonary hypertension (PH) encompasses a syndrome of diseases that are characterized by elevated pulmonary artery pressure and pulmonary vascular remodeling and that frequently lead to right ventricular (RV) failure and death. Several types of PH exhibit sexually dimorphic features in disease penetrance, presentation, and progression. Most sexually dimorphic features in PH have been described in pulmonary arterial hypertension (PAH), a devastating and progressive pulmonary vasculopathy with a 3-year survival rate <60%. While patient registries show that women are more susceptible to development of PAH, female PAH patients display better RV function and increased survival compared to their male counterparts, a phenomenon referred to as the "estrogen paradox" or "estrogen puzzle" of PAH. Recent advances in the field have demonstrated that multiple sex hormones, receptors, and metabolites play a role in the estrogen puzzle and that the effects of hormone signaling may be time and compartment specific. While the underlying physiological mechanisms are complex, unraveling the estrogen puzzle may reveal novel therapeutic strategies to treat and reverse the effects of PAH/PH. In this article, we (i) review PH classification and pathophysiology; (ii) discuss sex/gender differences observed in patients and animal models; (iii) review sex hormone synthesis and metabolism; (iv) review in detail the scientific literature of sex hormone signaling in PAH/PH, particularly estrogen-, testosterone-, progesterone-, and dehydroepiandrosterone (DHEA)-mediated effects in the pulmonary vasculature and RV; (v) discuss hormone-independent variables contributing to sexually dimorphic disease presentation; and (vi) identify knowledge gaps and pathways forward. © 2020 American Physiological Society. Compr Physiol 10:125-170, 2020.

Pulmonary Complications of Portal Hypertension

The most common pulmonary complications of chronic liver disease are hepatic hydrothorax, hepatopulmonary syndrome, and portopulmonary hypertension. Hepatic hydrothorax is a transudative pleural effusion in a patient with cirrhosis and no evidence of underlying cardiopulmonary disease. Hepatic hydrothorax develops owing to the movement of ascitic fluid into the pleural space. Hepatopulmonary syndrome and portopulmonary hypertension are pathologically linked by the presence of portal hypertension; however, their pathophysiologic mechanisms are significantly different. Hepatopulmonary syndrome is characterized by low pulmonary vascular resistance secondary to intrapulmonary vascular dilatations and hypoxemia; portopulmonary hypertension features elevated pulmonary vascular resistance and constriction/obstruction within the pulmonary vasculature.

Living Donor Liver Transplantation in Biliary Atresia Children with Pulmonary Hypertension

OBJECTIVE

Though living donor liver transplantation (LDLT) is commonly performed for pediatric patients with biliary atresia (BA), pulmonary hypertension (PH) is seldom encountered or reported previously. The aim of this study is mainly to identify the prevalence of PH in pediatric patients undergoing liver transplantation and assess whether PH significantly augment the operative risk and evaluate the outcomes in this series of patients.

DESIGN

Retrospectively cohort study.

SETTING

Renji hospital, Shanghai, China.

PARTICIPANTS

This study comprised 161 pediatric patients undergoing LDLT.

INTERVENTIONS

Patient diagnosed of PH in preoperative examination was compared to those without PH in intra- or post- operative complications or outcomes.

MEASUREMENTS AND MAIN RESULTS

We collected clinical records of LDLT surgery for pediatric patients during the year of 2016 in our hospital. Results suggested that pediatric patients undergoing LDLT had a substantial number of PH with a prevalence of 16.1% in this study. No significant difference was identified between two groups of patients regarding intraoperative outcomes and postoperative complications and mortality.

CONCLUSION

LDLT is a safe procedure in a selected group of BA patients with PH, however, further long-term clinical investigations and mechanical researches are needed.

The P2-receptor-mediated Ca2+ signalosome of the human pulmonary endothelium - implications for pulmonary arterial hypertension

Dysfunction of the pulmonary endothelium is associated with most lung diseases. Extracellular nucleotides modulate a plethora of endothelial functions in the lung such as vessel integrity, vasodilatation, inflammatory, and thrombotic responses as well as survival and DNA repair, mostly via Ca²⁺ signaling pathways. However, a comprehensive analysis of the molecular components of the underlying P2 receptor-mediated Ca²⁺ signaling pathways in the lung has not been conducted so far. Therefore, our aim was to identify the principal P2 receptor Ca²⁺ signalosome in the human pulmonary endothelium and investigate potential dysregulation in pulmonary vascular disease. Comparative transcriptomics and quantitative immunohistochemistry were performed on publicly available RNA sequencing and protein datasets to identify the specific expression profile of the P2-receptor Ca²⁺ signalosome in the healthy human pulmonary endothelium and endothelial cells (EC) dysfunctional due to loss of or defective bone morphogenetic protein receptor (BMPR2). Functional expression of signalosome components was tested by single cell Ca²⁺ imaging. Comparative transcriptome analysis of 11 endothelial cell subtypes revealed a specific P2 receptor Ca²⁺ signalosome signature for the pulmonary endothelium. Pulmonary endothelial expression of the most abundantly expressed Ca²⁺ toolkit genes CALM1, CALM2, VDAC1, and GNAS was confirmed by immunohistochemistry (IHC). P2RX1, P2RX4, P2RY6, and P2YR11 showed strong lung endothelial staining by IHC, P2X5, and P2Y1 were found to a much lesser extent. Very weak or no signals were detected for all other P2 receptors. Stimulation of human pulmonary artery (HPA) EC by purine nucleotides ATP, ADP, and AMP led to robust intracellular Ca²⁺ signals mediated through both P2X and P2Y receptors. Pyrimidine UTP and UDP-mediated Ca²⁺ signals were generated almost exclusively by activation of P2Y receptors. HPAEC made dysfunctional by siRNA-mediated BMPR2 depletion showed downregulation of 18 and upregulation of 19 P2 receptor Ca²⁺ signalosome genes including PLCD4, which was found to be upregulated in iPSC-EC from BMPR2-mutant patients with pulmonary arterial hypertension. In conclusion, the human pulmonary endothelium expresses a distinct functional subset of the P2 receptor Ca²⁺ signalosome. Composition of the P2 receptor Ca²⁺ toolkit in the pulmonary endothelium is susceptible to genetic disturbances likely contributing to an unfavorable pulmonary disease phenotype found in pulmonary arterial hypertension.

The Search for Disease-Modifying Therapies in Pulmonary Hypertension

Pulmonary hypertension (PH) and its severe subtype pulmonary arterial hypertension (PAH) encompass a set of multifactorial diseases defined by sustained elevation of pulmonary arterial pressure and pulmonary vascular resistance leading to right ventricular failure and subsequent death. Pulmonary hypertension is characterized by vascular remodeling in association with smooth muscle cell proliferation of the arterioles, medial thickening, and plexiform lesion formation. Despite our recent advances in understanding its pathogenesis and related therapeutic discoveries, PH still remains a progressive disease without a cure. Nevertheless, development of drugs that specifically target molecular pathways involved in disease pathogenesis has led to improvement in life quality and clinical outcomes in patients with PAH. There are presently more than 12 Food and Drug Administration-approved vasodilator drugs in the United States for the treatment of PAH; however, mortality with contemporary therapies remains high. More recently, there have been exuberant efforts to develop new pharmacologic therapies that target the fundamental origins of PH and thus could represent disease-modifying opportunities. This review aims to summarize recent developments on key signaling pathways and molecular targets that drive PH disease progression, with emphasis on new therapeutic options under development.

Role of the Aryl Hydrocarbon Receptor/ARNT/Cytochrome P450 System in Pulmonary Vascular Diseases

RATIONALE

CYPs (cytochrome p450) are critically involved in the metabolism of xenobiotics and toxins. Given that pulmonary hypertension is strongly associated with environmental exposure, we hypothesize that CYPs play a role in the development and maintenance of pathological vascular remodeling.

OBJECTIVE

We sought to identify key CYPs that could link drug or hormone metabolism to the development of pulmonary hypertension.

METHODS AND RESULTS

We searched in Medline (PubMed) database, as well as http://www.clinicaltrials.gov, for CYPs associated with many key aspects of pulmonary arterial hypertension including, but not limited to, severe pulmonary hypertension, estrogen metabolism, inflammation mechanisms, quasi-malignant cell growth, drug susceptibility, and metabolism of the pulmonary arterial hypertension-specific drugs.

CONCLUSIONS

We postulate a hypothesis where the AhR (aryl hydrocarbon receptor) mediates aberrant cell growth via expression of different CYPs associated with estrogen metabolism and inflammation.

Vascular syndromes in liver cirrhosis

Liver cirrhosis is associated with multiple vascular syndromes affecting almost all body systems. Many of these syndromes are directly related to impaired liver function and sometimes reversible after liver transplantation while others arise secondary to portal hypertension and ascites. Altered expression of angiogenic and vasoactive compounds (most importantly nitric oxide), endothelial dysfunction, dysregulated neurohormonal control, and systemic inflammatory state play differential roles in mediating homeostatic instability and abnormal vasogenic response. Important vascular features encountered in liver disease include portal hypertension, splanchnic overflow, abnormal angiogenesis and shunts, portopulmonary syndrome, hepatopulmonary syndrome, and systemic hyperdynamic circulation. Redistribution of effective circulatory volume deviating from vital organs and pooling in splanchnic circulation is also encountered in liver patients which may lead to devastating outcomes as hepatorenal syndrome. Etiologically, vascular syndromes are not isolated phenomena and vascular dysfunction in one system may lead to the development of another in a different system. This review focuses on understanding the pathophysiological factors underlying vascular syndromes related to chronic liver disease and the potential links among them. Many of these syndromes are associated with high mortality, thus it is crucial to look for early biomarkers for these syndromes and develop novel preventive and therapeutic strategies.

The Role of Sex in the Pathophysiology of Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterised by increased pulmonary vascular resistance and pulmonary artery remodelling as result of increased vascular tone and vascular cell proliferation, respectively. Eventually, this leads to right heart failure. Heritable PAH is caused by a mutation in the bone morphogenetic protein receptor-II (BMPR-II). Female susceptibility to PAH has been known for some time, and most recent figures show a female-to-male ratio of 4:1. Variations in the female sex hormone estrogen and estrogen metabolism modify FPAH risk, and penetrance of the disease in BMPR-II mutation carriers is increased in females. Several lines of evidence point towards estrogen being pathogenic in the pulmonary circulation, and thus increasing the risk of females developing PAH. Recent studies have also suggested that estrogen metabolism may be crucial in the development and progression of PAH with studies indicating that downstream metabolites such as 16α-hydroxyestrone are upregulated in several forms of experimental pulmonary hypertension (PH) and can cause pulmonary artery smooth muscle cell proliferation and subsequent vascular remodelling. Conversely, other estrogen metabolites such as 2-methoxyestradiol have been shown to be protective in the context of PAH. Estrogen may also upregulate the signalling pathways of other key mediators of PAH such as serotonin.

Regulation of Smooth Muscle Cell Proliferation by NADPH Oxidases in Pulmonary Hypertension

Hyperproliferation of pulmonary arterial smooth muscle cells is a key component of vascular remodeling in the setting of pulmonary hypertension (PH). Numerous studies have explored factors governing the changes in smooth muscle cell phenotype that lead to the increased wall thickness, and have identified various potential candidates. A role for reactive oxygen species (ROS) has been well documented in PH. ROS can be generated from a variety of sources, including mitochondria, uncoupled nitric oxide synthase, xanthine oxidase, and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. In this article, we will review recent data supporting a role for ROS generated from NADPH oxidases in promoting pulmonary arterial smooth muscle cell proliferation during PH.

Estimation of Endostatin level in pulmonary arterial hypertension patients and its relation with some parameters

Biomarkers are attractive non-invasive tools for estimating and monitoring pulmonary arterial hypertension (PAH) disease and for predicting survival in patients with PAH; therefore, many studies encouraged the investigation of new biomarkers to facilitate the diagnosis of PAH. Endostatin (ES) is an endogenous inhibitor of angiogenesis. It is produced by proteolytic cleavage of the collagen XVIII that is present in both normal and cancerous tissue. In vitro examination shows that ES can manage endothelial cells (EC) physiology in ways that could influence angiogenesis. For example, solvent ES hinders EC movement and prompts improvements of the cytoskeleton that incorporate the loss of Actin stretch strands and central grips. This effect embraces restrictions on the α5β1integrins, Tropomyosin, and putative heparan sulfate proteoglycans. Consequences for the human EC cytoskeleton include Es-induced down-regulation of Mitogen-actuated Protein Kinase (MAPK), Focal Adhesion Kinase (FAK), the Urokinase Plasminogen Activator (uPA) System, and the RhoA GTPase. Human ES has likewise been shown in a few investigations to repress EC multiplication. Moreover, ES-instigated cell cycle capture in the G1 stage is joined by Cyclin D1 down-regulation. Of note, ES blocks the proliferation and organization of endothelial cells into new blood vessels, and in animal studies, ES also inhibits angiogenesis and the growth of both primary tumors and secondary metastasis. ES was initially identified by its capacity to inhibit tumor angiogenesis in vitro and also in vivo. It can also be found in both healthy and patient’ serum, and has been detected in peripheral circulation. ES could be an attractive, non-invasive prognostic marker for some diseases, notably PAH. Therefore, the presented work is aimed at investigating the ES level in blood serum as a biomarker for detection, diagnosis and early treatment of PAH patients. In doing so, the association is ascertained between gender, age, body mass index (BMI), waist circumferences, smoking, types of PAH (primary and secondary) and this potential biomarker is assessed in PAH patients.

Sexually Dimorphic Regulation of EET Synthesis and Metabolism: Roles of Estrogen

Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid via cytochrome P450 (CYP)/epoxygenase and are hydrolyzed by soluble epoxide hydrolase (sEH). Circulating and tissue levels of EETs are controlled by CYP (EET synthesis) and sEH (EET degradation). Therefore, both increases in CYP activity and decreases in sEH expression potentiate EET bioavailability, responses that prevail in the female sex as a function of estrogen. This mini review, based on subtitles listed, briefly summarizes studies focusing specifically on (1) female-specific potentiation of CYP/epoxygenase activity to compensate for the endothelial dysfunction; and (2) estrogen-dependent downregulation of sEH expression, which yields divergent actions in both systemic and pulmonary circulation, respectively.

Estrogen-Potentiating EET Synthesis in Response to Endothelial Dysfunction: This section summarizes the current understanding regarding the roles of estrogen in facilitating EET synthesis in response to endothelial dysfunction. In this regard, estrogen recruitment of EET-driven signaling serves as a back-up mechanism, which compensates for NO deficiency to preserve endothelium-dependent vasodilator responses and maintain normal blood pressure.

Estrogen-Dependent Downregulation of Ephx2/sEH Expression: This section focuses on molecular mechanisms responsible for the female-specific downregulation of sEH expression.

Roles of EETs in Systemic Circulation, as a Function of Estrogen-Dependent Downregulation of sEH: This section summarizes studies conducted on animals that are either deficient in the Ephx2 gene (sEH-KO) or have been treated with sEH inhibitors (sEHIs), and exhibit EET-mediated cardiovascular protections in the cerebral, coronary, skeletal, and splanchnic circulations. In particular, the estrogen-inherent silencing of the Ephx2 gene duplicates the action of sEH deficiency, yielding comparable adaptations in attenuated myogenic vasoconstriction, enhanced shear stress-induced vasodilation, and improved cardiac contractility among female WT mice, male sEH-KO and sEHI-treated mice.

Roles of Estrogen-Driven EET Production in Pulmonary Circulation: This section reviews epidemiological and clinical studies that provide the correlation between the polymorphism, or mutation of gene(s) involving estrogen metabolism and female predisposition to pulmonary hypertension, and specifically addresses an intrinsic causation between the estrogen-dependent downregulation of Ephx2 gene/sEH expression and female-susceptibility of being pulmonary hypertensive, a topic that has never been explored before. Additionally, the issue of the “estrogen paradox” in the incidence and prognosis of pulmonary hypertension is discussed.