Genomics of pulmonary arterial hypertension: implications for therapy

Profile of Endothelin-1, Nitric Oxide, and Prostacyclin Levels in Pulmonary Arterial Hypertension Related to Uncorrected Atrial Septal Defect: Results from a Single Center Study in Indonesia

Methods

The study design was cross-sectional. The subjects were adult uncorrected secundum ASD with PAH. Pulmonary artery pressure was measured with right heart catheterization. Pulmonary venous blood was obtained during catheterization for measuring endothelin-1, prostacyclin, and nitric oxide. Correlation tests were performed to determine any association between biomarkers and mean pulmonary artery pressure (mPAP). The levels of biomarkers were compared based on the severity of PAH. Statistical significance was determined at p < 0.05.

Results

Forty-four subjects were enrolled in this study. Endothelin-1 level and mPAP had significant moderate positive correlation (r = 0.423 and p value = 0.004). However, no significant correlation was observed between prostacyclin, nitric oxide levels, and mPAP. The pattern of endothelin-1, prostacyclin, and nitric oxide was distinctive. Levels of endothelin-1 were incrementally increased from mild, moderate, to severe PAH. The levels of prostacyclin and nitric oxide had similar pattern in association with the severity of PAH, which was increased in mild-to-moderate PAH but decreased in severe PAH.

Conclusions

There was a distinctive pattern of endothelin-1, prostacyclin, and nitric oxide based on severity of PAH in adult uncorrected ASD. Significant correlations existed between endothelin-1 and the severity of PAH and mPAP.

Early intervention in the management of pulmonary arterial hypertension: clinical and economic outcomes

Pulmonary arterial hypertension (PAH) has a high morbidity rate and is fatal if left untreated. Increasing evidence supports early intervention, possibly with initial combination therapy. PAH-specific pharmaceuticals, however, are expensive and may have serious adverse effects, particularly when used in combination. The currently dynamic health care economy reinforces the need for a review of early intervention from both outcomes and economic perspectives. We aimed to review the clinical and economic impact of PAH therapy, particularly examining drug cost, hospitalization burden, and health care economics impact, and the effect of early intervention on clinical outcomes. We searched PubMed, Scopus, Ovid, and MEDLINE databases from 2005 to 2017 for studies comparing drug cost, clinical outcomes, and hospitalization burden associated with therapy for PAH. Emerging data indicate that early therapy is effective, but drug therapy is expensive, particularly with combination therapy. Efficacy studies also generally show benefit of combination therapy for patients in World Health Organization functional class II, with a consistent decrease in hospitalization. Pharmacoeconomic studies are limited but indicate that increased pharmacy costs are at least partially offset by decreased health care utilization, particularly inpatient care. Modeling also shows a cost benefit with combination therapy at 2 years. Nonetheless, more rigorously collected health care economic data should be incorporated into future drug efficacy trials to provide a clearer understanding of the impact and the associated cost benefit of early PAH therapy. Increasing evidence in support of early intervention and combination therapy for PAH is associated with rising medication costs that are largely offset by reduced hospitalization, on the basis of the currently available literature. Nonetheless, the studies performed to date have methodologic limitations that highlight the need for prospective studies using more robust economic modeling.

Novel approaches to pulmonary arterial hypertension drug discovery

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a rare disorder associated with abnormally elevated pulmonary pressures that, if untreated, leads to right heart failure and premature death. The goal of drug development for PAH is to develop effective therapies that halt, or ideally, reverse the obliterative vasculopathy that results in vessel loss and obstruction of blood flow to the lungs.

AREAS COVERED

This review summarizes the current approach to candidate discovery in PAH and discusses the currently available drug discovery methods that should be implemented to prioritize targets and obtain a comprehensive pharmacological profile of promising compounds with well-defined mechanisms.

EXPERT OPINION

To improve the successful identification of leading drug candidates, it is necessary that traditional pre-clinical studies are combined with drug screening strategies that maximize the characterization of biological activity and identify relevant off-target effects that could hinder the clinical efficacy of the compound when tested in human subjects. A successful drug discovery strategy in PAH will require collaboration of clinician scientists with medicinal chemists and pharmacologists who can identify compounds with an adequate safety profile and biological activity against relevant disease mechanisms.

Diagnostic dilemmas in pulmonary hypertension

Dilemmas persist in the screening, assessment, and follow-up of patients with pulmonary hypertension, relating to issues of whom and how to screen, how to resolve ambiguities in the clinical classification of patients with multiple potential substrates of pulmonary vascular disease, how to interpret test results, how to integrate multiple clinical parameters into a global diagnosis, how to use ambiguous test results, how to determine disease severity and prognosis, and how to monitor patients on treatment. This article describes how to incorporate available information into the diagnostic process, and where lack of concrete data should impose caution in patient management.

Plexiform vasculopathy of severe pulmonary arterial hypertension and microRNA expression

BACKGROUND

Recent studies have revealed that microRNAs (miRNAs) play a key role in the control of angiogenesis and vascular remodeling. Specific miRNAs in plexiform vasculopathy of severe pulmonary arterial hypertension (PAH) in humans have not yet been investigated.

METHODS

We analyzed expression of miR-143/145 (vascular smooth muscle-specific), miR-126 (endothelial-specific) and related mRNAs in plexiform (PLs) and concentric lesions (CLs), which had been laser-microdissected from specimens of formalin-fixed, paraffin-embedded, explanted lungs of PAH patients (n = 12) and unaffected controls (n = 8). Samples were analyzed by real-time polymerase chain reaction, and protein expression was determined by immunohistochemistry.

RESULTS

Expression levels of miR-143/145 and its target proteins (e.g., myocardin, smooth muscle myosin heavy chain) were found to be significantly higher in CLs than in PLs, whereas miR-126 and VEGF-A were significantly up-regulated in PLs when compared with CLs, indicating a more prominent angiogenic phenotype of PL. This correlates with a down-regulation of miR-204 as well as an up-regulation of miR-21 in PLs, which in turn corresponds to enhanced cell proliferation.

CONCLUSIONS

Our findings show that morphologic changes of plexiform vasculopathy in the end-stage PAH lung are reflected by alterations at the miRNA level.