Prostaglandin E1 Attenuates Pulmonary Artery Remodeling by Activating Phosphorylation of CREB and the PTEN Signaling Pathway

RNA m6A methylation and regulatory proteins in pulmonary arterial hypertension

m6A (N6‑methyladenosine) is the most common and abundant apparent modification in mRNA of eukaryotes. The modification of m6A is regulated dynamically and reversibly by methyltransferase (writer), demethylase (eraser), and binding protein (reader). It plays a significant role in various processes of mRNA metabolism, including regulation of transcription, maturation, translation, degradation, and stability. Pulmonary arterial hypertension (PAH) is a malignant cardiopulmonary vascular disease characterized by abnormal proliferation of pulmonary artery smooth muscle cells. Despite the existence of several effective and targeted therapies, there is currently no cure for PAH and the prognosis remains poor. Recent studies have highlighted the crucial role of m6A modification in cardiovascular diseases. Investigating the role of RNA m6A methylation in PAH could provide valuable insights for drug development. This review aims to explore the mechanism and function of m6A in the pathogenesis of PAH and discuss the potential targeting of RNA m6A methylation modification as a treatment for PAH.

Low-dose vanadium pentoxide perturbed lung metabolism associated with inflammation and fibrosis signaling in male animal and in vitro models

Vanadium is available as a dietary supplement and also is known to be toxic if inhaled, yet little information is available concerning the effects of vanadium on mammalian metabolism when concentrations found in food and water. Vanadium pentoxide (V+5) is representative of the most common dietary and environmental exposures, and prior research shows that low-dose V+5 exposure causes oxidative stress measured by glutathione oxidation and protein S-glutathionylation. We examined the metabolic impact of V+5 at relevant dietary and environmental doses (0.01, 0.1, and 1 ppm for 24 h) in human lung fibroblasts (HLFs) and male C57BL/6J mice (0.02, 0.2, and 2 ppm in drinking water for 7 mo). Untargeted metabolomics using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) showed that V+5 induced significant metabolic perturbations in both HLF cells and mouse lungs. We noted 30% of the significantly altered pathways in HLF cells, including pyrimidines and aminosugars, fatty acids, mitochondrial and redox pathways, showed similar dose-dependent patterns in mouse lung tissues. Alterations in lipid metabolism included leukotrienes and prostaglandins involved in inflammatory signaling, which have been associated with the pathogenesis of idiopathic pulmonary fibrosis (IPF) and other disease processes. Elevated hydroxyproline levels and excessive collagen deposition were also present in lungs from V+5-treated mice. Taken together, these results show that oxidative stress from environmental V+5, ingested at low levels, could alter metabolism to contribute to common human lung diseases.NEW & NOTEWORTHY We used relevant dietary and environmental doses of Vanadium pentoxide (V+5) to examine its metabolic impact in vitro and in vivo. Using liquid chromatography-high-resolution mass spectrometry (LC-HRMS), we found significant metabolic perturbations, with similar dose-dependent patterns observed in human lung fibroblasts and male mouse lungs. Alterations in lipid metabolism included inflammatory signaling, elevated hydroxyproline levels, and excessive collagen deposition were present in V+5-treated lungs. Our findings suggest that low levels of V+5 could trigger pulmonary fibrotic signaling.

Silencing EIF3A ameliorates pulmonary arterial hypertension through HDAC1 and PTEN/PI3K/AKT pathway in vitro and in vivo

Pulmonary vascular remodeling caused by the excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs) is the hallmark feature of pulmonary arterial hypertension (PAH). Eukaryotic initiation factor 3 subunit A (EIF3A) exhibited proliferative activity in multiple cell types. The present study investigated the role of EIF3A in the progression of PAH. A monocrotaline (MCT)-induced PAH rat model was constructed, and adeno-associated virus type 1 (AAV1) carrying EIF3A shRNA was intratracheally delivered to PAH rats to block EIF3A expression. PASMCs were isolated from rats and treated with PDGF-BB to simulate PASMC proliferation, and shRNA for EIF3 was conducted to investigate the mechanism behind the role of EIF3A in PASMC function in vitro. EIF3A expression was upregulated in pulmonary arteries, and EIF3A inhibition effectively improved pulmonary hypertension and right ventricular hypertrophy and suppressed MCT-induced vascular remodeling in vivo. In addition, we found that genetic knockdown of EIF3A reduced PDGF-triggered proliferation and arrested cell cycle, accompanied by downregulated proliferation-related protein expression in PASMCs. Mechanistically, the histone deacetylase 1 (HDAC1)-mediated PTEN/PI3K/AKT pathway was recognized as a primary mechanism in PAH progression. Silencing EIF3A decreased HDAC1 expression, and further inhibited the excessive proliferation of PASMCs by increasing the phosphatase and tension homolog (PTEN) expression and suppressing the AKT phosphorylation. Notably, HDAC1 expression reversed the effect of silencing EIF3A on PAH and PTEN/PI3K/AKT pathway. Collectively, silencing EIF3A improved PAH by decreasing PASMC proliferation through the HDAC1-mediated PTEN/PI3K/AKT pathway. These findings suggest that targeting EIF3A may represent a potential approach for the treatment of PAH.

PTEN: An Emerging Potential Target for Therapeutic Intervention in Respiratory Diseases

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a potent tumor suppressor that regulates several key cellular processes, including proliferation, survival, genomic integrity, migration, and invasion, via PI3K-dependent and independent mechanisms. A subtle decrease in PTEN levels or catalytic activity is implicated not only in cancer but also in a wide spectrum of other diseases, including various respiratory diseases. A systemic overview of the advances in the molecular and cellular mechanisms of PTEN involved in the initiation and progression of respiratory diseases may offer novel targets for the development of effective therapeutics for the treatment of respiratory diseases. In the present review, we highlight the novel findings emerging from current research on the role of PTEN expression and regulation in airway pathological conditions such as asthma/allergic airway inflammation, pulmonary hypertension (PAH), chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and other acute lung injuries (ALI). Moreover, we discuss the clinical implications of PTEN alteration and recently suggested therapeutic possibilities for restoration of PTEN expression and function in respiratory diseases.

The potential role of TRPV1 in pulmonary hypertension: Angel or demon?

Pulmonary hypertension (PH) is a pathological state defined by increased pulmonary artery pressure, the pathogenesis of which is related to genetic mutations, intracellular calcium ([Ca²⁺]_i), inflammation and proliferation. Transient receptor potential vanilloid subfamily member 1 (TRPV1) is a nonselective cation channel expressed in neural and nonneural cells, including pulmonary vessels and nerves. As a calcium channel, TRPV1 can make vessels contracted, and promote smooth muscle cells proliferation through calcium-dependent transcription factors. Activation of TRPV1 in sensory nerves can release neuropeptides, including calcitonin gene-related peptide (CGRP), substance P (SP), and somatostatin (SST), which can regulate inflammation via transcription factor NF-kB. Considering the increased level of [Ca²⁺]_i and inflammation in the pathogenesis of PH, our review summarizes the role of TRPV1 in PH with regard to [Ca²⁺]_i, neuropeptides, and inflammation. In view of the limited research illustrating the relationship between TRPV1 and PH directly, our review also considers the role of TRPV1 in other types of vascular inflammation. Through this review, we hope to raise awareness about the function of TRPV1 in PH.

MicroRNA‑132 mediates proliferation and migration of pulmonary smooth muscle cells via targeting PTEN

Pulmonary arterial hypertension (PAH) is a severe and progressive disease characterized by the remodeling of small pulmonary arteries. The aberrant proliferation of pulmonary arterial smooth muscle cells (PASMCs) is the primary feature of PAH. MicroRNA (miR)‑132 has been demonstrated to inhibit the proliferation of vascular smooth muscle cells and repress neointimal formation. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a direct target of miR‑132 that has been revealed to be involved in the development of PAH. However, the role of miR‑132 in PAH remains unclear. The present study demonstrated that miR‑132 expression was upregulated in monocrotaline‑induced PAH rats and platelet‑derived growth factor‑induced PASMCs. In addition, treatment of PASMCs with miR‑132 mimics inhibited their proliferation, whereas miR‑132 inhibition exhibited the opposite effects. Furthermore, miR‑132 mimics promoted cell migration and maintained the PASMC contractile phenotype. Finally, the expression levels of PTEN were significantly decreased in PAH and PASMCs treated with miR‑132 mimics. Taken collectively, the data suggested that miR‑132 regulated PASMC function via PTEN and that it may be used as a potential target for the treatment of PAH.