Novel molecular insights and public omics data in pulmonary hypertension

Understanding pulmonary hypertension: the need for an integrative metabolomics and transcriptomics approach

Pulmonary hypertension (PH), characterised by mean pulmonary arterial pressure (mPAP) >20 mm Hg at rest, is a complex pathophysiological disorder associated with multiple clinical conditions. The high prevalence of the disease along with increased mortality and morbidity makes it a global health burden. Despite major advances in understanding the disease pathophysiology, much of the underlying complex molecular mechanism remains to be elucidated. Lack of a robust diagnostic test and specific therapeutic targets also poses major challenges. This review provides a comprehensive update on the dysregulated pathways and promising candidate markers identified in PH patients using the transcriptomics and metabolomics approach. The review also highlights the need of using an integrative multi-omics approach for obtaining insight into the disease at a molecular level. The integrative multi-omics/pan-omics approach envisaged to help in bridging the gap from genotype to phenotype is outlined. Finally, the challenges commonly encountered while conducting omics-driven studies are also discussed.

Unraveling the epigenetic landscape of pulmonary arterial hypertension: implications for personalized medicine development

Pulmonary arterial hypertension (PAH) is a multifactorial disease associated with the remodeling of pulmonary blood vessels. If left unaddressed, PAH can lead to right heart failure and even death. Multiple biological processes, such as smooth muscle proliferation, endothelial dysfunction, inflammation, and resistance to apoptosis, are associated with PAH. Increasing evidence suggests that epigenetic factors play an important role in PAH by regulating the chromatin structure and altering the expression of critical genes. For example, aberrant DNA methylation and histone modifications such as histone acetylation and methylation have been observed in patients with PAH and are linked to vascular remodeling and pulmonary vascular dysfunction. In this review article, we provide a comprehensive overview of the role of key epigenetic targets in PAH pathogenesis, including DNA methyltransferase (DNMT), ten-eleven translocation enzymes (TET), switch-independent 3A (SIN3A), enhancer of zeste homolog 2 (EZH2), histone deacetylase (HDAC), and bromodomain-containing protein 4 (BRD4). Finally, we discuss the potential of multi-omics integration to better understand the molecular signature and profile of PAH patients and how this approach can help identify personalized treatment approaches.

Effects of Trimetazidine on Right Ventricular Function and Ventricular Remodeling in Patients with Pulmonary Artery Hypertension: A Randomised Controlled Trial

BACKGROUND

Pulmonary artery hypertension (PAH) is a chronic and progressive disease. Although current therapy has improved the disease prognosis, PAH has a poor survival rate. The key feature leading to disease progression and death is right ventricular (RV) failure.

METHODS AND RESULTS

We assessed the role of trimetazidine, a fatty acid beta-oxidation (FAO) inhibitor, in right ventricular function, remodeling, and functional class in PAH patients, with a placebo-controlled double-blind, case-crossover trial. Twenty-seven PAH subjects were enrolled, randomized, and assigned to trimetazidine or placebo for three months and then reallocated to the other study arm. The primary endpoint was RV morphology and function change after three months of treatment. Secondary endpoints were the change in exercise capacity assessed by a 6 min walk test after three months of treatment and the change in pro-BNP and Galectin-3 plasma levels after three months. Trimetazidine use was safe and well-tolerated. After three months of treatment, patients in the trimetazidine group showed a small but significant reduction of RV diastolic area, and a substantial increase in the 6 min walk distance (418 vs. 438 mt, p = 0.023), without significant changes in biomarkers.

CONCLUSIONS

A short course of trimetazidine is safe and well-tolerated on PAH patients, and it is associated with significant increases in the 6MWT and minor but significant improvement in RV remodeling. The therapeutic potential of this drug should be evaluated in larger clinical trials.

A signal recognition particle-related joint model of LASSO regression, SVM-RFE and artificial neural network for the diagnosis of systemic sclerosis-associated pulmonary hypertension

Background: Systemic sclerosis-associated pulmonary hypertension (SSc-PH) is one of the most common causes of death in patients with systemic sclerosis (SSc). The complexity of SSc-PH and the heterogeneity of clinical features in SSc-PH patients contribute to the difficulty of diagnosis. Therefore, there is a pressing need to develop and optimize models for the diagnosis of SSc-PH. Signal recognition particle (SRP) deficiency has been found to promote the progression of multiple cancers, but the relationship between SRP and SSc-PH has not been explored. Methods: First, we obtained the GSE19617 and GSE33463 datasets from the Gene Expression Omnibus (GEO) database as the training set, GSE22356 as the test set, and the SRP-related gene set from the MSigDB database. Next, we identified differentially expressed SRP-related genes (DE-SRPGs) and performed unsupervised clustering and gene enrichment analyses. Then, we used least absolute shrinkage and selection operator (LASSO) regression and support vector machine-recursive feature elimination (SVM-RFE) to identify SRP-related diagnostic genes (SRP-DGs). We constructed an SRP scoring system and a nomogram model based on the SRP-DGs and established an artificial neural network (ANN) for diagnosis. We used receiver operating characteristic (ROC) curves to identify the SRP-related signature in the training and test sets. Finally, we analyzed immune features, signaling pathways, and drugs associated with SRP and investigated SRP-DGs' functions using single gene batch correlation analysis-based GSEA. Results: We obtained 30 DE-SRPGs and found that they were enriched in functions and pathways such as "protein targeting to ER," "cytosolic ribosome," and "coronavirus disease-COVID-19". Subsequently, we identified seven SRP-DGs whose expression levels and diagnostic efficacy were validated in the test set. As one signature, the area under the ROC curve (AUC) values for seven SRP-DGs were 0.769 and 1.000 in the training and test sets, respectively. Predictions made using the nomogram model are likely beneficial for SSc-PH patients. The AUC values of the ANN were 0.999 and 0.860 in the training and test sets, respectively. Finally, we discovered that some immune cells and pathways, such as activated dendritic cells, complement activation, and heme metabolism, were significantly associated with SRP-DGs and identified ten drugs targeting SRP-DGs. Conclusion: We constructed a reliable SRP-related ANN model for the diagnosis of SSc-PH and investigated the possible role of SRP in the etiopathogenesis of SSc-PH by bioinformatics methods to provide a basis for precision and personalized medicine.

Angiotensin-(1-9) in hypertension

Angiotensin-(1-9) [Ang-(1-9)] is a peptide of the non-canonical renin-angiotensin system (RAS) synthesized from angiotensin I by the monopeptidase angiotensin-converting enzyme type 2 (ACE2). Using osmotic minipumps, infusion of Ang-(1-9) consistently reduces blood pressure in several rat hypertension models. In these animals, hypertension-induced end-organ damage is also decreased. Several pieces of evidence suggest that Ang-(1-9) is the endogenous ligand that binds and activates the type-2 angiotensin II receptor (AT2R). Activation of AT2R triggers different tissue-specific signaling pathways. This phenomenon could be explained by the ability of AT2R to form different heterodimers with other G protein-coupled receptors. Because of the antihypertensive and protective effects of AT2R activation by Ang-(1-9), associated with a short half-life of RAS peptides, several synthetic AT2R agonists have been synthesized and assayed. Some of them, particularly CGP42112, C21 and novokinin, have demonstrated antihypertensive properties. Only two synthetic AT2R agonists, C21 and LP2-3, have been tested in clinical trials, but none of them like an antihypertensive. Therefore, Ang-(1-9) is a promising antihypertensive drug that reduces hypertension-induced end-organ damage. However, further research is required to translate this finding successfully to the clinic.

Mechanistic and therapeutic perspectives of baicalin and baicalein on pulmonary hypertension: A comprehensive review

Pulmonary hypertension (PH) is a chronic and fatal disease, for which new therapeutic drugs and approaches are needed urgently. Baicalein and baicalin, the active compounds of the traditional Chinese medicine, Scutellaria baicalensis Georgi, exhibit a wide range of pharmacological activities. Numerous studies involving in vitro and in vivo models of PH have revealed that the treatment with baicalin and baicalein may be effective. This review summarizes the potential mechanisms driving the beneficial effects of baicalin and baicalein treatment on PH, including anti-inflammatory response, inhibition of pulmonary smooth muscle cell proliferation and endothelial-to-mesenchymal transformation, stabilization of the extracellular matrix, and mitigation of oxidative stress. The pharmacokinetics of these compounds have also been reviewed. The therapeutic potential of baicalin and baicalein warrants their continued study as natural treatments for PH.