An Overview of Circulating Pulmonary Arterial Hypertension Biomarkers

Assessing causal relationships between gut microbiotas, metabolites, and pulmonary arterial hypertension through univariate Mendelian randomization study and bioinformatics analysis

BACKGROUND

Recent research has linked gut microbiotas and metabolites to the development and progression of pulmonary arterial hypertension (PAH) through the gut-lung axis. However, current studies on the causal relationship between gut microbiotas, gut microbiota derived metabolites, and PAH lack conclusive evidence. This study employed Mendelian randomization and bioinformatics analysis to reveal the possible causal links among them.

METHODS

Summary statistics of gut microbiotas, metabolites, and PAH were from GWAS. Univariate Mendelian randomization (inverse variance weighted and weighted median), reverse Mendelian randomization, and verification through other PAH GWAS cohorts were used to analyze the possible causal relationships between these gut microbiotas or gut microbiota derived metabolites and PAH. In addition, Cochran's Q statistic, MR-Egger regression intercept, MR-PRESSO global test, and the leave-one-out method were used for the sensitivity analysis. Based on this, we carried out an initial bioinformatics analysis to investigate its potential biological mechanisms.

RESULTS

Preliminary screening of the present research revealed four gut microbiotas ( Genus Eubacteriumfissicatenagroup , Genus RuminococcaceaeUCG002, Genus Tyzzerella3, and Genus Sutterella) and one metabolite (taurolithocholate 3-sulfate) correlated with PAH. However, after validation in other PAH GWAS cohorts, only genetically increased Genus Tyzzerella3 (odds ratio: 0.54, 95% confidence interval: 0.37-0.80, P  = 0.0018) correlated with a reduced risk for PAH, a relationship may be related to the keratan sulfate and glycosphingolipid synthesis. No significant heterogeneity, pleiotropy, or reversal causation effect was observed ( P  > 0.05).

CONCLUSION

Our Mendelian randomization analysis establishes a significant correlation between Genus Tyzzerella3 and PAH, positioning it as a prominent protective factor for PAH.

Evaluation of Plasma Nitric Oxide and Serum Endothelial Nitric Oxide Synthase in Pulmonary Hypertensive Dogs: A Clinical and Echocardiography Investigation

Nitric oxide (NO), an endogenous vasodilator, has been proposed as a biomarker for pulmonary hypertension (PH) in humans. NO is synthesized by endothelial nitric oxide synthase (eNOS). Alterations in NO/eNOS have not been studied in dogs with PH. We assessed alterations in NO and eNOS in the blood of dogs with PH (n = 17) and healthy dogs (n = 10) and analyzed their correlations with echocardiographic parameters. The results showed significantly higher plasma NO and serum eNOS levels in dogs with PH compared with healthy dogs. Dogs with PH and ascites (n = 11) had significantly lower plasma NO levels than those without ascites (n = 6) and presented a decreasing eNOS trend. In dogs with PH, plasma NO was positively correlated with left ventricular hemodynamics, right ventricular compliance, and pulmonary distensibility, but was negatively correlated with pulmonary vascular resistance and right cardiac remodeling. Serum eNOS was positively correlated with the main pulmonary artery diameter. Increments in NO/eNOS reflected compensatory responses to cardiovascular changes in PH. These compensations were downward in the advanced stages. Other factors may also impact NO/eNOS compensation. Although the role of NO/eNOS as biomarkers for PH in dogs remains equivocal, they may indicate compensatory consequences of cardiovascular alterations.

Trends and patterns in pulmonary arterial hypertension-associated hospital admissions among methamphetamine users: a decade-long study

Background

Pulmonary arterial hypertension (PAH) is a rare, chronic, progressive form of pulmonary hypertension in which increased arterial pressure causes remodeling of the arterial system and is associated with heart failure. Methamphetamine is a stimulant that has recently become a focus in PAH research, but the recent trends and demographics of this cohort of patients are not known. The study aimed to analyze the overall trends and demographics of PAH patients with and without concurrent methamphetamine usage.

Methods

The study used the National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), and Agency for Healthcare Research and Quality (AHRQ) from 2008 to 2020 to calculate nationally weighted estimates for both conditions by ICD-9 and ICD-10 diagnosis codes. We used several statistical measures, including descriptive statistics with design-based chi-square and t-tests, trend analysis with Cochran-Armitage test, generalized linear models, and other data preprocessing measures.

Results

A significant increase was evident in patients with pulmonary arterial hypertension (PAH) and concurrent methamphetamine use (9.2-fold). Most of the hospitalized patients were males (59.16%), aged 41-64 (45.77%), White (68.64%), from the West (53.09%), with Medicaid (50.48%), and with median income <$25,000. The rate of increase over the period was higher for males (11.8-fold), race (not sure which race; please check and modify), aged 41-64 (11.3-fold), and in the South (15.1-fold). An overall adjusted prevalence ratio (PR) for PAH hospitalizations among concurrent methamphetamine users was 32.19 (CI = 31.19-33.22) compared to non-users. With respective reference categories, the significantly higher PR was evident for males, patients aged 41-64, White, with Medicare, median income <$25,000, all regions compared to Northeast, length of hospital stays, and conditions, including chronic pulmonary disease, diabetes, hypertension, obesity, and peripheral vascular disorders.

Conclusion

This study reveals a national overall and demographic-specific trend of increasing PAH with concurrent methamphetamine usage and associated factors. The findings may help to understand the current patterns and identify the vulnerable sociodemographic cohorts for further research and to take appropriate policy measures.

Levels of Plasma Endothelin-1, Circulating Endothelial Cells, Endothelial Progenitor Cells, and Cytokines after Cardiopulmonary Bypass in Children with Congenital Heart Disease: Role of Endothelin-1 Regulation

Congenital heart disease (CHD) can be complicated by pulmonary arterial hypertension (PAH). Cardiopulmonary bypass (CPB) for corrective surgery may cause endothelial dysfunction, involving endothelin-1 (ET-1), circulating endothelial cells (CECs), and endothelial progenitor cells (EPCs). These markers can gauge disease severity, but their levels in children's peripheral blood still lack consensus for prognostic value. The aim of our study was to investigate changes in ET-1, cytokines, and the absolute numbers (Ɲ) of CECs and EPCs in children 24 h before and 48 h after CPB surgery to identify high-risk patients of complications. A cohort of 56 children was included: 41 cases with CHD-PAH (22 with high pulmonary flow and 19 with low pulmonary flow) and 15 control cases. We observed that Ɲ-CECs increased in both CHD groups and that Ɲ-EPCs decreased in the immediate post-surgical period, and there was a strong negative correlation between ET-1 and CEC before surgery, along with significant changes in ET-1, IL8, IL6, and CEC levels. Our findings support the understanding of endothelial cell precursors' role in endogenous repair and contribute to knowledge about endothelial dysfunction in CHD.

Circulating Biomarkers in Pulmonary Arterial Hypertension: An Update

Pulmonary arterial hypertension (PAH) is a rare subtype of group 1 pulmonary hypertension (PH) diseases, characterized by high pulmonary artery pressure leading to right ventricular dysfunction and potential life-threatening consequences. PAH involves complex mechanisms: vasoconstriction, vascular remodeling, endothelial dysfunction, inflammation, oxidative stress, fibrosis, RV remodeling, cellular hypoxia, metabolic imbalance, and thrombosis. These mechanisms are mediated by several pathways, involving molecules like nitric oxide and prostacyclin. PAH diagnosis requires clinical evaluation and right heart catheterization, confirming a value of mPAP ≥ 20 mmHg at rest and often elevated pulmonary vascular resistance (PVR). Even if an early and accurate diagnosis is crucial, PAH still lacks effective biomarkers to assist in its diagnosis and prognosis. Biomarkers could contribute to arousing clinical suspicion and serve for prognosis prediction, risk stratification, and dynamic monitoring in patients with PAH. The aim of the present review is to report the main novelties on new possible biomarkers for the diagnosis, prognosis, and treatment monitoring of PAH.

Unmasking a Silent Threat: Improving Pulmonary Hypertension Screening Methods for Interstitial Lung Disease Patients

This article provides a comprehensive overview of the latest literature on the diagnostics and treatment of pulmonary hypertension (PH) associated with interstitial lung disease (ILD). Heightened suspicion for PH arises when the advancement of dyspnoea in ILD patients diverges from the expected pattern of decline in pulmonary function parameters. The complexity of PH associated with ILD (PH-ILD) diagnostics is emphasized by the limitations of transthoracic echocardiography in the ILD population, necessitating the exploration of alternative diagnostic approaches. Cardiac magnetic resonance imaging (MRI) emerges as a promising tool, offering insights into hemodynamic parameters and providing valuable prognostic information. The potential of biomarkers, alongside pulmonary function and cardiopulmonary exercise tests, is explored for enhanced diagnostic and prognostic precision. While specific treatments for PH-ILD remain limited, recent studies on inhaled treprostinil provide new hope for improved patient outcomes.

Differential responses of pulmonary vascular cells from PAH patients and controls to TNFα and the effect of the BET inhibitor JQ1

BACKGROUND

Pulmonary arterial hypertension (PAH) encompasses a group of diseases characterized by raised pulmonary vascular resistance, resulting from vascular remodelling and inflammation. Bromodomain and extra-terminal (BET) proteins are required for the expression of a subset of NF-κB-induced inflammatory genes which can be inhibited by the BET mimic JQ1+. We hypothesised that JQ+ would supress TNFα-driven inflammatory responses in human pulmonary vascular cells from PAH patients.

METHODS

Immunohistochemical staining of human peripheral lung tissue (N = 14 PAH and N = 12 non-PAH) was performed for the BET proteins BRD2 and 4. Human pulmonary microvascular endothelial cells (HPMEC) and pulmonary artery smooth muscle cells (HPASMC) from PAH patients (N = 4) and non-PAH controls (N = 4) were stimulated with TNFα in presence or absence of JQ1+ or its inactive isomer JQ1-. IL-6 and -8 mRNA was measured by RT-qPCR and protein levels by ELISA. Chromatin immunoprecipitation analysis was performed using EZ-ChIP™ and NF-κB p65 activation determined using a TransAm kit. MTT assay was used to measure cell viability.

RESULTS

Nuclear staining of BRD2 and BRD4 was significantly (p < 0.0001) increased in the lung vascular endothelial and smooth muscle cells from PAH patients compared to controls with normal lung function. TNFα-driven IL-6 release from both HPMECs and HPASMCs was greater in PAH cells than control cells. Levels of CXCL8/IL-8 protein release was higher in PAH HPASMCs than in control cells with similar release observed in HPMECs. TNFα-induced recruitment of activated NF-κB p65 to the IL-6 and CXCL8/IL-8 promoters were similar in both cell types and between subject groups. JQ1+ suppressed TNFα-induced IL-6 and CXCL8/IL-8 release and mRNA expression to a comparable extent in control and PAH HPMECs and HPASMCs. JQ1 had a greater efficacy on IL-6 release in HPMEC and on CXCL8/IL-8 release in HPASMC.

CONCLUSION

BET inhibition decreases TNFα driven inflammation in primary pulmonary vascular cells. The anti-inflammatory actions of JQ1 suggests distinct cell-specific regulatory control of these genes. BET proteins could be a target for future therapies for PAH.

Pulmonary hypertension in patients with multiple myeloma: A comprehensive review

Multiple myeloma (MM) is a common hematological malignancy resulting from clonal proliferation of plasma cells and is defined by criteria set forth by the international myeloma working group. Pulmonary hypertension (PH) is defined by an elevated mean pulmonary artery pressure >20 mmHg measured during right heart catheterization. Echocardiography-diagnosed PH is relatively common in patients with MM and has been associated with increased mortality, morbidity, and poor stem cell transplant outcomes. PH in patients with MM (PH-MM) is usually multifactorial in origin. MM disease-specific factors, host comorbidities, and treatment-related adverse effects are the key factors for the development of PH-MM. Pragmatically, patients with PH-MM can be grouped into either (i) PH in patients with a new diagnosis of MM or (ii) PH that develops or worsens along the way of MM treatment. In the latter group, drug-induced PH, venous thromboembolism, pulmonary veno occlusive disease, and cardiotoxicity should be considered as possible causes. PH-MM should be evaluated and managed in a multidisciplinary setting. Select individuals with PH-MM could be considered for pulmonary vasodilators at PH-specialized centers.

Treatment Response Evaluation by Computed Tomography Pulmonary Vasculature Analysis in Patients With Chronic Thromboembolic Pulmonary Hypertension

OBJECTIVE

To quantitatively assess the pulmonary vasculature using non-contrast computed tomography (CT) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) pre- and post-treatment and correlate CT-based parameters with right heart catheterization (RHC) hemodynamic and clinical parameters.

MATERIALS AND METHODS

A total of 30 patients with CTEPH (mean age, 57.9 years; 53% female) who received multimodal treatment, including riociguat for ≥ 16 weeks with or without balloon pulmonary angioplasty and underwent both non-contrast CT for pulmonary vasculature analysis and RHC pre- and post-treatment were included. The radiographic analysis included subpleural perfusion parameters, including blood volume in small vessels with a cross-sectional area ≤ 5 mm² (BV5) and total blood vessel volume (TBV) in the lungs. The RHC parameters included mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR), and cardiac index (CI). Clinical parameters included the World Health Organization (WHO) functional class and 6-minute walking distance (6MWD).

RESULTS

The number, area, and density of the subpleural small vessels increased after treatment by 35.7% (P < 0.001), 13.3% (P = 0.028), and 39.3% (P < 0.001), respectively. The blood volume shifted from larger to smaller vessels, as indicated by an 11.3% increase in the BV5/TBV ratio (P = 0.042). The BV5/TBV ratio was negatively correlated with PVR (r = -0.26; P = 0.035) and positively correlated with CI (r = 0.33; P = 0.009). The percent change across treatment in the BV5/TBV ratio correlated with the percent change in mPAP (r = -0.56; P = 0.001), PVR (r = -0.64; P < 0.001), and CI (r = 0.28; P = 0.049). Furthermore, the BV5/TBV ratio was inversely associated with the WHO functional classes I-IV (P = 0.004) and positively associated with 6MWD (P = 0.013).

CONCLUSION

Non-contrast CT measures could quantitatively assess changes in the pulmonary vasculature in response to treatment and were correlated with hemodynamic and clinical parameters.

Serum Biomarkers in Connective Tissue Disease-Associated Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening complication of connective tissue diseases (CTDs) characterised by increased pulmonary arterial pressure and pulmonary vascular resistance. CTD-PAH is the result of a complex interplay among endothelial dysfunction and vascular remodelling, autoimmunity and inflammatory changes, ultimately leading to right heart dysfunction and failure. Due to the non-specific nature of the early symptoms and the lack of consensus on screening strategies-except for systemic sclerosis, with a yearly transthoracic echocardiography as recommended-CTD-PAH is often diagnosed at an advanced stage, when the pulmonary vessels are irreversibly damaged. According to the current guidelines, right heart catheterisation is the gold standard for the diagnosis of PAH; however, this technique is invasive, and may not be available in non-referral centres. Hence, there is a need for non-invasive tools to improve the early diagnosis and disease monitoring of CTD-PAH. Novel serum biomarkers may be an effective solution to this issue, as their detection is non-invasive, has a low cost and is reproducible. Our review aims to describe some of the most promising circulating biomarkers of CTD-PAH, classified according to their role in the pathophysiology of the disease.