Mechanisms of disease: pulmonary arterial hypertension

Advances in the potential of nebulized inhalation for the treatment of pulmonary arterial hypertension

Pulmonary hypertension is a pathophysiologic manifestation of a heterogeneous group of diseases, with the main pathophysiologic mechanisms being persistent pulmonary vasoconstriction and irreversible vascular remodeling. The impact significantly affects the prognosis of patients with pulmonary hypertension. If it is not treated and intervened in time, it may lead to right ventricular failure and further endanger the patient's life. Within the past decade or so, nebulized inhalation therapy is considered to have advantages in the treatment of pulmonary hypertension as a safe, limited, and rapid therapy, for example, inhaled vasodilators (prostate analogs, nitroglycerin, carbon monoxide analogs sildenafil, and nitroprusside), inhaled anti-inflammatory and antiproliferative agents (simvastatin, and selatinib), and inhaled peroxides (levocetirizine) have been recognized as emerging therapeutic approaches in the treatment of pulmonary hypertension as emerging therapeutic approaches. Therefore, this article provides a brief review of recent advances in the potential of nebulized inhaled vasodilators, anti-inflammatory and antiproliferative agents, and anti-peroxides for the treatment of pulmonary hypertension, with the aim of providing different therapeutic options for the treatment of pulmonary hypertension, enhancing the quality of survival, alleviating symptoms, and improving the prognosis of patients with this condition.

Muscular hyperplasia in Crohn's disease strictures: through thick and thin

Fibrostenosing Crohn's disease (CD) represents a challenging clinical condition characterized by the development of symptomatic strictures within the gastrointestinal tract. Despite therapeutic advancements in managing inflammation, the progression of fibrostenotic complications remains a significant concern, often necessitating surgical intervention. Recent investigations have unveiled the pivotal role of smooth muscle cell hyperplasia in driving luminal narrowing and clinical symptomatology. Drawing parallels to analogous inflammatory conditions affecting other organs, such as the airways and blood vessels, sheds light on common underlying mechanisms of muscular hyperplasia. This review synthesizes current evidence to elucidate the mechanisms underlying smooth muscle cell proliferation in CD-associated strictures, offering insights into potential therapeutic targets. By highlighting the emerging significance of muscle thickening as a novel therapeutic target, this review aims to inform future research endeavors and clinical strategies with the goal to mitigate the burden of fibrostenotic complications in CD and other conditions.

Cardiovascular disease in connective tissue disease-associated interstitial lung disease: A systematic review and meta-analysis of observational studies

OBJECTIVES

We performed a systematic review and meta-analysis to assess whether patients with connective tissue disease (CTD)-associated interstitial lung diseases (ILD) have an increased prevalence of cardiovascular (CV) disease and to validate associated risk factors.

METHODS

The PRISMA guidelines and PICO model were followed. We searched PubMed, Embase, Cochrane Library databases, Scopus, and Directory of Open Access Journals from inception to April 2024.

RESULTS

Thirteen studies comprising of 12,520 patients were included. Patients with CTD-ILD had a significantly increased risk of CV disease than patients with CTD (relative risk [RR] = 1.65, 95 % confidence interval [CI]: 1.41, 1.93), which are related to the proportion of men (P = 0.001) and the proportion of smokers (P = 0.045). Subgroup analysis found that patients with CTD-ILD had a higher risk of heart failure (RR = 2.84, 95 % CI: 1.50, 5.39), arrhythmia (RR = 1.55, 95 % CI: 1.22, 1.97) than patients with CTD. Another subgroup analysis showed that RA-ILD and SSc-ILD were associated with an increased risk of CV disease, but not IIM-ILD and MCTD-ILD (RA-ILD: RR = 2.19, 95 % CI: 1.27, 3.80; SSc-ILD: RR = 1.53, 95 % CI: 1.29, 1.82). Besides, patients with CTD-ILD had a higher prevalence of pulmonary arterial hypertension (RR = 2.48, 95 % CI: 1.69, 3.63) than patients with CTD.

CONCLUSIONS

Patients with CTD-ILD had a 1.65 times increased risk of CV than patients with CTD-non-ILD, with increased prevalence of heart failure and arrhythmia. The risk of CV disease in SSc-ILD and RA-ILD is increased and we should pay more attention to male smokers. In addition, compared with CTD patients, CTD-ILD patients had a higher risk of pulmonary arterial hypertension.

Low Thyroid Hormones Level Attenuates Mitochondrial Dysfunction and Right Ventricular Failure in Pulmonary Hypertensive Rats

PURPOSE

This study is to investigate the repercussions of hypothyroidism in the pathophysiological progression of pulmonary arterial hypertension (PAH).

METHODS

While the control (CTL, n = 5) male Wistar rats received vehicle, PAH was induced with monocrotaline (MCT group, n = 15). Hypothyroidism was induced in a subset of rats by methimazole 3 weeks prior to the MCT injection (MMZ + MCT group, n = 15). Plasma thyroid hormones were measured by radioimmunoassay. Electrocardiographic, echocardiographic, and hemodynamic analyses were performed to evaluate the progression of PAH. Gene expression of antioxidant enzymes and cardiac hypertrophy markers were assessed by qPCR. Mitochondrial respiration, ATP levels, and ROS production were measured in right ventricular (RV) samples.

RESULTS

Plasma T3 and T4 decreased in both MCT and MMZ + MCT groups (p < 0.05). Right ventricular systolic pressure (RVSP) increased, and RV - dP/dt, + dP/dt, and contractility index decreased in the MCT versus the CTL group and remained within control levels in the MMZ + MCT group (p < 0.05). Relative RV weight, RV wall thickness, RV diastolic area, and relative lung weight were augmented in the MCT versus the CTL group, whereas all parameters were improved to the CTL levels in the MMZ + MCT group (p < 0.05). Only the MCT group exhibited an increased duration of QTc interval compared to the baseline period (p < 0.05). ADP-induced mitochondrial respiration and ATP levels were decreased, and ROS production was increased in MCT versus the CTL group (p < 0.05), while the MMZ + MCT group exhibited increased mitochondrial respiration versus the MCT group (p < 0.05).

CONCLUSION

Hypothyroidism attenuated the RV mitochondrial dysfunction and the pathophysiological progression of MCT-induced PAH.

miR-30d Attenuates Pulmonary Arterial Hypertension via Targeting MTDH and PDE5A and Modulates the Beneficial Effect of Sildenafil

Pulmonary arterial hypertension (PAH) is associated with aberrant pulmonary vascular smooth muscle cell (PASMC) function and vascular remodeling. MiR-30d plays an important role in the pathogenesis of several cardiovascular disorders. However, the function of miR-30d in PAH progression remained unknown. Our study shows that circulating miR-30d level is significantly reduced in the plasma from PAH patients. In miR-30d transgenic (TG) rats, overexpressing miR-30d attenuates monocrotaline (MCT)-induced pulmonary hypertension (PH) and pulmonary vascular remodeling. Increasing miR-30d also inhibits platelet-derived growth factor-bb (PDGF-bb)-induced proliferation and migration of human PASMC. Metadherin (MTDH) and phosphodiesterase 5A (PDE5A) are identified as direct target genes of miR-30d. Meanwhile, nuclear respiratory factor 1 (NRF1) acts as a positive upstream regulator of miR-30d. Using miR-30d knockout (KO) rats treated with sildenafil, a PDE5A inhibitor that is used in clinical PAH therapies, it is further found that suppressing miR-30d partially attenuates the beneficial effect of sildenafil against MCT-induced PH and vascular remodeling. The present study shows a protective effect of miR-30d against PAH and pulmonary vascular remodeling through targeting MTDH and PDE5A and reveals that miR-30d modulates the beneficial effect of sildenafil in treating PAH. MiR-30d should be a prospective target to treat PAH and pulmonary vascular remodeling.

Immunotherapy for Pulmonary Arterial Hypertension: From the Pathogenesis to Clinical Management

Pulmonary hypertension (PH) is a progressive cardiovascular disease, which may lead to severe cardiopulmonary dysfunction. As one of the main PH disease groups, pulmonary artery hypertension (PAH) is characterized by pulmonary vascular remodeling and right ventricular dysfunction. Increased pulmonary artery resistance consequently causes right heart failure, which is the major reason for morbidity and mortality in this disease. Although various treatment strategies have been available, the poor clinical prognosis of patients with PAH reminds us that further studies of the pathological mechanism of PAH are still needed. Inflammation has been elucidated as relevant to the initiation and progression of PAH, and plays a crucial and functional role in vascular remodeling. Many immune cells and cytokines have been demonstrated to be involved in the pulmonary vascular lesions in PAH patients, with the activation of downstream signaling pathways related to inflammation. Consistently, this influence has been found to correlate with the progression and clinical outcome of PAH, indicating that immunity and inflammation may have significant potential in PAH therapy. Therefore, we reviewed the pathogenesis of inflammation and immunity in PAH development, focusing on the potential targets and clinical application of anti-inflammatory and immunosuppressive therapy.

Discovery and Optimization of Hsp110 and sGC Dual-Target Regulators for the Treatment of Pulmonary Arterial Hypertension

Currently, bifunctional agents with vasodilation and ameliorated vascular remodeling effects provide more advantages for the treatment of pulmonary arterial hypertension (PAH). In this study, we first screened the hit 1 with heat shock protein 110 (Hsp110) inhibition effect from our in-house compound library with soluble guanylate cyclase (sGC) activity. Subsequently, a series of novel bisamide derivatives were designed and synthesized as Hsp110/sGC dual-target regulators based on hit 1. Among them, 17i exhibited optimal Hsp110 and sGC molecular activities as well as remarkable cell malignant phenotypes inhibitory and vasodilatory effects in vitro. Moreover, compared to riociguat, 17i showed superior efficacy in attenuating pulmonary vascular remodeling and right ventricular hypertrophy via Hsp110 suppression in hypoxia-induced PAH rat models (i.g.). Notably, our study successfully demonstrated that the simultaneous regulation of Hsp110 and sGC dual targets was a novel and feasible strategy for PAH therapy, providing a promising lead compound for anti-PAH drug discovery.

Therapeutic Potential of Natural Compounds Acting through Epigenetic Mechanisms in Cardiovascular Diseases: Current Findings and Future Directions

Cardiovascular diseases (CVDs) remain a leading global cause of morbidity and mortality. These diseases have a multifaceted nature being influenced by a multitude of biochemical, genetic, environmental, and behavioral factors. Epigenetic modifications have a crucial role in the onset and progression of CVD. Epigenetics, which regulates gene activity without altering the DNA's primary structure, can modulate cardiovascular homeostasis through DNA methylation, histone modification, and non-coding RNA regulation. The effects of environmental stimuli on CVD are mediated by epigenetic changes, which can be reversible and, hence, are susceptible to pharmacological interventions. This represents an opportunity to prevent diseases by targeting harmful epigenetic modifications. Factors such as high-fat diets or nutrient deficiencies can influence epigenetic enzymes, affecting fetal growth, metabolism, oxidative stress, inflammation, and atherosclerosis. Recent studies have shown that plant-derived bioactive compounds can modulate epigenetic regulators and inflammatory responses, contributing to the cardioprotective effects of diets. Understanding these nutriepigenetic effects and their reversibility is crucial for developing effective interventions to combat CVD. This review delves into the general mechanisms of epigenetics, its regulatory roles in CVD, and the potential of epigenetics as a CVD therapeutic strategy. It also examines the role of epigenetic natural compounds (ENCs) in CVD and their potential as intervention tools for prevention and therapy.

Zinc attenuates monocrotaline-induced pulmonary hypertension in rats through upregulation of A20

Pulmonary hypertension (PH) is characterized by excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), in which inflammatory signaling caused by activation of the NF-κB pathway plays an important role. A20 is an important negative regulator of the NF-κB pathway, and zinc promotes the expression of A20 and exerts a protective effect against various diseases (e.g. COVID19) by inhibiting the inflammatory signaling. The role of A20 and intracellular zinc signaling in PH has been explored, but the extracellular zinc signaling is not well understood, and whether zinc has protective effects on PH is still elusive. Using inductively coupled plasma mass spectrometry (ICP-MS), we studied the alteration of trace elements during the progression of monocrotaline (MCT)-induced PH and found that serum zinc concentration was decreased with the onset of PH accompanied by abnormalities of other three elements, including copper, chromium, and magnesium. Zinc chloride injection with the dosage of 5 mg/kg intraperitoneally partially corrected this abnormality and inhibited the progression of PH. Zinc supplementation induced the expression of A20 in lung tissue and reduce the inflammatory responses. In vitro, zinc supplementation time-dependently upregulated the expression of A20 in PASMCs, therefore correcting the excessive proliferation and migration of cells caused by hypoxia. Using genetically encoded-FRET based zinc probe, we found that these effects of zinc ions are not achieved by entering cells, but most likely by activating cell surface zinc receptor (ZnR/GPR39). These results provide the first evidence of the effectiveness of zinc supplementation in the treatment of PH.

BRCC3 Regulation of ALK2 in Vascular Smooth Muscle Cells: Implication in Pulmonary Hypertension

BACKGROUND

An imbalance of antiproliferative BMP (bone morphogenetic protein) signaling and proliferative TGF-β (transforming growth factor-β) signaling is implicated in the development of pulmonary arterial hypertension (PAH). The posttranslational modification (eg, phosphorylation and ubiquitination) of TGF-β family receptors, including BMPR2 (bone morphogenetic protein type 2 receptor)/ALK2 (activin receptor-like kinase-2) and TGF-βR2/R1, and receptor-regulated Smads significantly affects their activity and thus regulates the target cell fate. BRCC3 modifies the activity and stability of its substrate proteins through K63-dependent deubiquitination. By modulating the posttranslational modifications of the BMP/TGF-β-PPARγ pathway, BRCC3 may play a role in pulmonary vascular remodeling, hence the pathogenesis of PAH.

METHODS

Bioinformatic analyses were used to explore the mechanism by which BRCC3 deubiquitinates ALK2. Cultured pulmonary artery smooth muscle cells (PASMCs), mouse models, and specimens from patients with idiopathic PAH were used to investigate the rebalance between BMP and TGF-β signaling in regulating ALK2 phosphorylation and ubiquitination in the context of pulmonary hypertension.

RESULTS

BRCC3 was significantly downregulated in PASMCs from patients with PAH and animals with experimental pulmonary hypertension. BRCC3, by de-ubiquitinating ALK2 at Lys-472 and Lys-475, activated receptor-regulated Smad1/5/9, which resulted in transcriptional activation of BMP-regulated PPARγ, p53, and Id1. Overexpression of BRCC3 also attenuated TGF-β signaling by downregulating TGF-β expression and inhibiting phosphorylation of Smad3. Experiments in vitro indicated that overexpression of BRCC3 or the de-ubiquitin-mimetic ALK2-K472/475R attenuated PASMC proliferation and migration and enhanced PASMC apoptosis. In SM22α-BRCC3-Tg mice, pulmonary hypertension was ameliorated because of activation of the ALK2-Smad1/5-PPARγ axis in PASMCs. In contrast, Brcc3-/- mice showed increased susceptibility of experimental pulmonary hypertension because of inhibition of the ALK2-Smad1/5 signaling.

CONCLUSIONS

These results suggest a pivotal role of BRCC3 in sustaining pulmonary vascular homeostasis by maintaining the integrity of the BMP signaling (ie, the ALK2-Smad1/5-PPARγ axis) while suppressing TGF-β signaling in PASMCs. Such rebalance of BMP/TGF-β pathways is translationally important for PAH alleviation.

Niclosamide modulates phenotypic switch and inflammatory responses in human pulmonary arterial smooth muscle cells

Excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs) represent key steps of pulmonary vascular remodeling, leading to the development of pulmonary arterial hypertension (PAH) and right ventricular failure. Niclosamide (NCL), an FDA-approved anthelmintic, has been shown to regulate cell proliferation, migration, invasion, and apoptosis through a variety of signaling pathways. However, its role on modulating the phenotypic switch and inflammatory responses in PASMCs remains unclear. In this study, cell proliferation assay showed that NCL inhibited PDGF-BB induced proliferation of human PASMCs in a dose-dependent manner. Western blot analysis further confirmed a notable reduction in the expression of cyclin D1 and PCNA proteins. Subsequently, flow cytometry analysis demonstrated that NCL induced an increased percentage of cells in the G1 phase while promoting apoptosis in PASMCs. Moreover, both scratch wound assay and transwell assay confirmed that NCL decreased PDGF-BB-induced migration of PASMCs. Mechanistically, western blot revealed that pretreatment of PASMCs with NCL markedly restored the protein levels of SMA, SM22, and calponin, while reducing phosphorylation of P38/STAT3 signaling in the presence of PDGF-BB. Interestingly, macrophages adhesion assay showed that NCL markedly reduced recruitment of Calcein-AM labeled RAW264.7 by TNFα-stimulated PASMCs. Western blot revealed that NCL suppressed TNFα-induced expression of both of VCAM-1 and ICAM-1 proteins. Furthermore, pretreatment of PASMCs with NCL significantly inhibited NLRP3 inflammasome activity through reducing NLRP3, AIM2, mature interleukin-1β (IL-β), and cleaved Caspase-1 proteins expression. Together, these results suggested versatile effects of NCL on controlling of proliferation, migration, and inflammatory responses in PASMCs through modulating different pathways, indicating that repurposing of NCL may emerge as a highly effective drug for PAH treatment.

Inhibition of Vascular Smooth Muscle Cell Proliferation by ENPP1: The Role of CD73 and the Adenosine Signaling Axis

The Ectonucleotide Pyrophosphatase/Phosphodiesterase 1 (ENPP1) ectoenzyme regulates vascular intimal proliferation and mineralization of bone and soft tissues. ENPP1 variants cause Generalized Arterial Calcification of Infancy (GACI), a rare genetic disorder characterized by ectopic calcification, intimal proliferation, and stenosis of large- and medium-sized arteries. ENPP1 hydrolyzes extracellular ATP to pyrophosphate (PPi) and AMP. AMP is the precursor of adenosine, which has been implicated in the control of neointimal formation. Herein, we demonstrate that an ENPP1-Fc recombinant therapeutic inhibits proliferation of vascular smooth muscle cells (VSMCs) in vitro and in vivo. Addition of ENPP1 and ATP to cultured VSMCs generated AMP, which was metabolized to adenosine. It also significantly decreased cell proliferation. AMP or adenosine alone inhibited VSMC growth. Inhibition of ecto-5'-nucleotidase CD73 decreased adenosine accumulation and suppressed the anti-proliferative effects of ENPP1/ATP. Addition of AMP increased cAMP synthesis and phosphorylation of VASP at Ser157. This AMP-mediated cAMP increase was abrogated by CD73 inhibitors or by A2aR and A2bR antagonists. Ligation of the carotid artery promoted neointimal hyperplasia in wild-type mice, which was exacerbated in ENPP1-deficient ttw/ttw mice. Prophylactic or therapeutic treatments with ENPP1 significantly reduced intimal hyperplasia not only in ttw/ttw but also in wild-type mice. These findings provide the first insight into the mechanism of the anti-proliferative effect of ENPP1 and broaden its potential therapeutic applications beyond enzyme replacement therapy.

Omega-3 polyunsaturated fatty acids and pulmonary arterial hypertension: Insights and perspectives

Pulmonary arterial hypertension (PAH) is a rare and progressive disorder that affects the pulmonary vasculature. Although recent developments in pharmacotherapy have extended the life expectancy of PAH patients, their 5-year survival remains unacceptably low, underscoring the need for multitarget and more comprehensive approaches to managing the disease. This should incorporate not only medical, but also lifestyle interventions, including dietary changes and the use of nutraceutical support. Among these strategies, n-3 polyunsaturated fatty acids (n-3 PUFAs) are emerging as promising agents able to counteract the inflammatory component of PAH. In this narrative review, we aim at analysing the preclinical evidence for the impact of n-3 PUFAs on the pathogenesis and the course of PAH. Although evidence for the role of n-3 PUFAs deficiencies in the development and progression of PAH in humans is limited, preclinical studies suggest that these dietary components may influence several aspects of the pathobiology of PAH. Further clinical research should test the efficacy of n-3 PUFAs on top of approved clinical management. These studies will provide evidence on whether n-3 PUFAs can genuinely serve as a valuable tool to enhance the efficacy of pharmacotherapy in the treatment of PAH.

Fluorinated perhexiline derivative attenuates vascular proliferation in pulmonary arterial hypertension smooth muscle cells

Increased proliferation and reduced apoptosis of pulmonary artery smooth muscle cells (PASMCs) is recognised as a universal hallmark of pulmonary arterial hypertension (PAH), in part related to the association with reduced pyruvate dehydrogenase (PDH) activity, resulting in decreased oxidative phosphorylation of glucose and increased aerobic glycolysis (Warburg effect). Perhexiline is a well-recognised carnitine palmitoyltransferase-1 (CPT1) inhibitor used in cardiac diseases, which reciprocally increases PDH activity, but is associated with variable pharmacokinetics related to polymorphic variation of the cytochrome P450-2D6 (CYP2D6) enzyme, resulting in the risk of neuro and hepatotoxicity in 'slow metabolisers' unless blood levels are monitored and dose adjusted. We have previously reported that a novel perhexiline fluorinated derivative (FPER-1) has the same therapeutic profile as perhexiline but is not metabolised by CYP2D6, resulting in more predictable pharmacokinetics than the parent drug. We sought to investigate the effects of perhexiline and FPER-1 on PDH flux in PASMCs from patients with PAH. We first confirmed that PAH PASMCs exhibited increased cell proliferation, enhanced phosphorylation of AKTSer473, ERK 1/2Thr202/Tyr204 and PDH-E1αSer293, indicating a Warburg effect when compared to healthy PASMCs. Pre-treatment with perhexiline or FPER-1 significantly attenuated PAH PASMC proliferation in a concentration-dependent manner and suppressed the activation of the AKTSer473 but had no effect on the ERK pathway. Perhexiline and FPER-1 markedly activated PDH (seen as dephosphorylation of PDH-E1αSer293), reduced glycolysis, and upregulated mitochondrial respiration in these PAH PASMCs as detected by Seahorse analysis. However, both perhexiline and FPER-1 did not induce apoptosis as measured by caspase 3/7 activity. We show for the first time that both perhexiline and FPER-1 may represent therapeutic agents for reducing cell proliferation in human PAH PASMCs, by reversing Warburg physiology.

C-type natriuretic peptide/cGMP/FoxO3 signaling attenuates hyperproliferation of pericytes from patients with pulmonary arterial hypertension

Pericyte dysfunction, with excessive migration, hyperproliferation, and differentiation into smooth muscle-like cells contributes to vascular remodeling in Pulmonary Arterial Hypertension (PAH). Augmented expression and action of growth factors trigger these pathological changes. Endogenous factors opposing such alterations are barely known. Here, we examine whether and how the endothelial hormone C-type natriuretic peptide (CNP), signaling through the cyclic guanosine monophosphate (cGMP) -producing guanylyl cyclase B (GC-B) receptor, attenuates the pericyte dysfunction observed in PAH. The results demonstrate that CNP/GC-B/cGMP signaling is preserved in lung pericytes from patients with PAH and prevents their growth factor-induced proliferation, migration, and transdifferentiation. The anti-proliferative effect of CNP is mediated by cGMP-dependent protein kinase I and inhibition of the Phosphoinositide 3-kinase (PI3K)/AKT pathway, ultimately leading to the nuclear stabilization and activation of the Forkhead Box O 3 (FoxO3) transcription factor. Augmentation of the CNP/GC-B/cGMP/FoxO3 signaling pathway might be a target for novel therapeutics in the field of PAH.

Pulmonary Hypertension in Connective Tissue Diseases Other than Systemic Sclerosis

Pulmonary hypertension (PH) is a known complication of certain connective tissue diseases (CTDs), with systemic sclerosis (SSc) being the most common in the Western world. However, PH in association with non-SSc CTD such as systemic lupus erythematous, mixed connective tissue disease, and primary Sjögren's syndrome constitutes a distinct subset of patients with inherently different epidemiologic profiles, pathophysiologic mechanisms, clinical features, therapeutic options, and prognostic implications. The purpose of this review is to inform a practical approach for clinicians evaluating patients with non-SSc CTD-associated PH.The development of PH in these patients involves a complex interplay between genetic factors, immune-mediated mechanisms, and endothelial cell dysfunction. Furthermore, the broad spectrum of CTD manifestations can contribute to the development of PH through various pathophysiologic mechanisms, including intrinsic pulmonary arteriolar vasculopathy (pulmonary arterial hypertension, Group 1 PH), left-heart disease (Group 2), chronic lung disease (Group 3), chronic pulmonary artery obstruction (Group 4), and unclear and/or multifactorial mechanisms (Group 5). The importance of diagnosing PH early in symptomatic patients with non-SSc CTD is highlighted, with a review of the relevant biomarkers, imaging, and diagnostic procedures required to establish a diagnosis.Therapeutic strategies for non-SSc PH associated with CTD are explored with an in-depth review of the medical, interventional, and surgical options available to these patients, emphasizing the CTD-specific considerations that guide treatment and aid in prognosis. By identifying gaps in the current literature, we offer insights into future research priorities that may prove valuable for patients with PH associated with non-SSc CTD.

The diverging roles of insulin-like growth factor binding proteins in pulmonary arterial hypertension

Pulmonary hypertension (PH) is a progressive, severe and to date not curable disease of the pulmonary vasculature. Alterations of the insulin-like growth factor 1 (IGF-1) system are known to play a role in vascular pathologies and IGF-binding proteins (IGFBPs) are important regulators of the bioavailability and function of IGFs. In this study, we show that circulating plasma levels of IGFBP-1, IGFBP-2 and IGFBP-3 are increased in idiopathic pulmonary arterial hypertension (IPAH) patients compared to healthy individuals. These binding proteins inhibit the IGF-1 induced IGF-1 receptor (IGF1R) phosphorylation and exhibit diverging effects on the IGF-1 induced signaling pathways in human pulmonary arterial cells (i.e. healthy as well as IPAH-hPASMCs, and healthy hPAECs). Furthermore, IGFBPs are differentially expressed in an experimental mouse model of PH. In hypoxic mouse lungs, IGFBP-1 mRNA expression is decreased whereas the mRNA for IGFBP-2 is increased. In contrast to IGFBP-1, IGFBP-2 shows vaso-constrictive properties in the murine pulmonary vasculature. Our analyses show that IGFBP-1 and IGFBP-2 exhibit diverging effects on IGF-1 signaling and display a unique IGF1R-independent kinase activation pattern in human pulmonary arterial smooth muscle cells (hPASMCs), which represent a major contributor of PAH pathobiology. Furthermore, we could show that IGFBP-2, in contrast to IGFBP-1, induces epidermal growth factor receptor (EGFR) signaling, Stat-3 activation and expression of Stat-3 target genes. Based on our results, we conclude that the IGFBP family, especially IGFBP-1, IGFBP-2 and IGFBP-3, are deregulated in PAH, that they affect IGF signaling and thereby regulate the cellular phenotype in PH.

A peripheral system disease-Pulmonary hypertension

Pulmonary hypertension (PH) is a cardiovascular disorder characterized by substantial morbidity and mortality rates. It is a chronic condition characterized by intricate pathogenesis and uncontrollable factors. We summarized the pathological effects of estrogen, genetics, neuroinflammation, intestinal microbiota, metabolic reorganization, and histone modification on PH. PH is not only a pulmonary vascular disease, but also a systemic disease. The findings emphasize that the onset of PH is not exclusively confined to the pulmonary vasculature, consequently necessitating treatment approaches that extend beyond targeting pulmonary blood vessels. Hence, the research on the pathological mechanism of PH is not limited to target organs such as pulmonary vessels, but also focuses on exploring other fields (such as estrogen, genetics, neuroinflammation, intestinal microbiota, metabolic reorganization, and histone modification).

GLI1+ Cells Contribute to Vascular Remodeling in Pulmonary Hypertension

BACKGROUND

The precise origin of newly formed ACTA2+ (alpha smooth muscle actin-positive) cells appearing in nonmuscularized vessels in the context of pulmonary hypertension is still debatable although it is believed that they predominantly derive from preexisting vascular smooth muscle cells (VSMCs).

METHODS

Gli1Cre-ERT2; tdTomatoflox mice were used to lineage trace GLI1+ (glioma-associated oncogene homolog 1-positive) cells in the context of pulmonary hypertension using 2 independent models of vascular remodeling and reverse remodeling: hypoxia and cigarette smoke exposure. Hemodynamic measurements, right ventricular hypertrophy assessment, flow cytometry, and histological analysis of thick lung sections followed by state-of-the-art 3-dimensional reconstruction and quantification using Imaris software were used to investigate the contribution of GLI1+ cells to neomuscularization of the pulmonary vasculature.

RESULTS

The data show that GLI1+ cells are abundant around distal, nonmuscularized vessels during steady state, and this lineage contributes to around 50% of newly formed ACTA2+ cells around these normally nonmuscularized vessels. During reverse remodeling, cells derived from the GLI1+ lineage are largely cleared in parallel to the reversal of muscularization. Partial ablation of GLI1+ cells greatly prevented vascular remodeling in response to hypoxia and attenuated the increase in right ventricular systolic pressure and right heart hypertrophy. Single-cell RNA sequencing on sorted lineage-labeled GLI1+ cells revealed an Acta2high fraction of cells with pathways in cancer and MAPK (mitogen-activated protein kinase) signaling as potential players in reprogramming these cells during vascular remodeling. Analysis of human lung-derived material suggests that GLI1 signaling is overactivated in both group 1 and group 3 pulmonary hypertension and can promote proliferation and myogenic differentiation.

CONCLUSIONS

Our data highlight GLI1+ cells as an alternative cellular source of VSMCs in pulmonary hypertension and suggest that these cells and the associated signaling pathways represent an important therapeutic target for further studies.

Exosomes enriched by miR-429-3p derived from ITGB1 modified Telocytes alleviates hypoxia-induced pulmonary arterial hypertension through regulating Rac1 expression

BACKGROUND

Recent studies have emphasized the critical role of Telocytes (TCs)-derived exosomes in organ tissue injury and repair. Our previous research showed a significant increase in ITGB1 within TCs. Pulmonary Arterial Hypertension (PAH) is marked by a loss of microvessel regeneration and progressive vascular remodeling. This study aims to investigate whether exosomes derived from ITGB1-modified TCs (ITGB1-Exo) could mitigate PAH.

METHODS

We analyzed differentially expressed microRNAs (DEmiRs) in TCs using Affymetrix Genechip miRNA 4.0 arrays. Exosomes isolated from TC culture supernatants were verified through transmission electron microscopy and Nanoparticle Tracking Analysis. The impact of miR-429-3p-enriched exosomes (Exo-ITGB1) on hypoxia-induced pulmonary arterial smooth muscle cells (PASMCs) was evaluated using CCK-8, transwell assay, and inflammatory factor analysis. A four-week hypoxia-induced mouse model of PAH was constructed, and H&E staining, along with Immunofluorescence staining, were employed to assess PAH progression.

RESULTS

Forty-five miRNAs exhibited significant differential expression in TCs following ITGB1 knockdown. Mus-miR-429-3p, significantly upregulated in ITGB1-overexpressing TCs and in ITGB1-modified TC-derived exosomes, was selected for further investigation. Exo-ITGB1 notably inhibited the migration, proliferation, and inflammation of PASMCs by targeting Rac1. Overexpressing Rac1 partly counteracted Exo-ITGB1's effects. In vivo administration of Exo-ITGB1 effectively reduced pulmonary vascular remodeling and inflammation.

CONCLUSIONS

Our findings reveal that ITGB1-modified TC-derived exosomes exert anti-inflammatory effects and reverse vascular remodeling through the miR-429-3p/Rac1 axis. This provides potential therapeutic strategies for PAH treatment.

Metallothionein 3 Potentiates Pulmonary Artery Smooth Muscle Cell Proliferation by Promoting Zinc-MTF1-ATG5 Axis-mediated Autophagosome Formation

Abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs) is one of the critical pathological mechanisms of pulmonary hypertension (PH), and therefore is gradually being adopted as an important direction for the treatment of PH. Metallothioneins (MTs) have been reported to be associated with PH, but the underlying mechanisms are not fully understood. Here, we demonstrated that the expression level of metallothionein 3 (MT3) was significantly increased in pulmonary arterioles from PH patients and chronic hypoxia-induced rat and mouse PH models, as well as in hypoxia-treated human PASMCs. Knockdown of MT3 significantly inhibited the proliferation of human PASMCs by arresting the cell cycle in the G1 phase, while overexpression of MT3 had the opposite effect. Mechanistically, we found that MT3 increased the intracellular zinc (Zn2+) concentration to enhance the transcriptional activity of metal-regulated transcription factor 1 (MTF1), which promoted the expression of autophagy-related gene 5 (ATG5), facilitating autophagosome formation. More importantly, MT3-induced autophagy and proliferation of human PASMCs were largely prevented by knockdown of MTF1 and ATG5. Therefore, in this study, we identified MT3-Zinc-MTF1-ATG5 as a novel pathway that affects PASMC proliferation by regulating autophagosome formation, suggesting that MT3 may be a novel target for the treatment of PH.

Molecular Insights into the Relationship Between Platelet Activation and Endothelial Dysfunction: Molecular Approaches and Clinical Practice

Platelets are one of the coagulation cells. When platelet activation occurs, many mediators are released and affect endothelial cells (ECs) and lead to endothelial dysfunction (ED). ED plays an important role in the pathogenesis of many diseases, including cardiovascular disease (CVD). Platelet are of important factors in ED. The release of mediators by platelets causes the stimulation of inflammatory pathways, oxidative stress, and apoptosis, which ultimately result in ED.On the other hand, platelet activation in CVD patients can be associated with a bad prognosis. Platelet activation can increase the level of markers such as p-selectin in the serum. Also, in this study, we have discussed the role of platelet as a diagnostic factor, as well as its use as a treatment option. In addition, we discussed some of the molecular pathways that are used to target platelet activation.

Inhalable Nitric Oxide Delivery Systems for Pulmonary Arterial Hypertension Treatment

Pulmonary arterial hypertension (PAH) is a severe medical condition characterized by elevated blood pressure in the pulmonary arteries. Nitric oxide (NO) is a gaseous signaling molecule with potent vasodilator effects; however, inhaled NO is limited in clinical practice because of the need for tracheal intubation and the toxicity of high NO concentrations. In this study, inhalable NO-releasing microspheres (NO inhalers) are fabricated to deliver nanomolar NO through a nebulizer. Two NO inhalers with distinct porous structures are prepared depending on the molecular weights of NO donors. It is confirmed that pore formation can be controlled by regulating the migration of water molecules from the external aqueous phase to the internal aqueous phase. Notably, open porous NO inhalers (OPNIs) can deliver NO deep into the lungs through a nebulizer. Furthermore, OPNIs exhibit vasodilatory and anti-inflammatory effects via sustained NO release. In conclusion, the findings suggest that OPNIs with highly porous structures have the potential to serve as tools for PAH treatment.

Emergencies in Pulmonary Hypertension

Pulmonary hypertension is a challenging disease entity with various underlying etiologies. The management of patients with pulmonary arterial hypertension (WHO Group 1) remains challenging especially in the critical care setting. With risk of high morbidity and mortality, these patients require a multidisciplinary team approach at a speciality care facility for pulmonary hypertension for comprehensive evaluation and rapid initiation of treatment. For acute decompensated right heart failure, management should concentrate on optimizing preload and after load with use of pulmonary vasodilator therapy. A careful evaluation of specialized situations is required for appropriate treatment response.

Integrated bioinformatics analysis and experimental animal models identify a robust biomarker and its correlation with the immune microenvironment in pulmonary arterial hypertension

Background

Pulmonary arterial hypertension (PAH) represents a substantial global risk to human health. This study aims to identify diagnostic biomarkers for PAH and assess their association with the immune microenvironment through the utilization of sophisticated bioinformatics techniques.

Methods

Based on two microarray datasets, differentially expressed genes (DEGs) were detected, and hub genes underwent a sequence of machine learning analyses. After pathways associated with PAH were assessed by gene enrichment analysis, the identified genes were validated using external datasets and confirmed in a monocrotaline (MCT)-induced rat model. In addition, three algorithms were employed to estimate the proportions of various immune cell types, and the link between hub genes and immune cells was substantiated.

Results

Using SVM, LASSO, and WGCNA, we identified seven hub genes, including (BPIFA1, HBA2, HBB, LOC441081, PI15, S100A9, and WIF1), of which only BPIFA1 remained stable in the external datasets and was validated in an MCT-induced rat model. Furthermore, the results of the functional enrichment analysis established a link between PAH and both metabolism and the immune system. Correlation assessment showed that BPIFA1 expression in the MCP-counter algorithm was negatively associated with various immune cell types, positively correlated with macrophages in the ssGSEA algorithm, and correlated with M1 and M2 macrophages in the CIBERSORT algorithm.

Conclusion

BPIFA1 serves as a modulator of PAH, with the potential to impact the immune microenvironment and disease progression, possibly through its regulatory influence on both M1 and M2 macrophages.

IL-6/gp130 signaling in CD4+ T cells drives the pathogenesis of pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterized by stenosis and occlusions of small pulmonary arteries, leading to elevated pulmonary arterial pressure and right heart failure. Although accumulating evidence shows the importance of interleukin (IL)-6 in the pathogenesis of PAH, the target cells of IL-6 are poorly understood. Using mice harboring the floxed allele of gp130, a subunit of the IL-6 receptor, we found substantial Cre recombination in all hematopoietic cell lineages from the primitive hematopoietic stem cell level in SM22α-Cre mice. We also revealed that a CD4+ cell-specific gp130 deletion ameliorated the phenotype of hypoxia-induced pulmonary hypertension in mice. Disruption of IL-6 signaling via deletion of gp130 in CD4+ T cells inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) and suppressed the hypoxia-induced increase in T helper 17 cells. To further examine the role of IL-6/gp130 signaling in more severe PH models, we developed Il6 knockout (KO) rats using the CRISPR/Cas9 system and showed that IL-6 deficiency could improve the pathophysiology in hypoxia-, monocrotaline-, and Sugen5416/hypoxia (SuHx)-induced rat PH models. Phosphorylation of STAT3 in CD4+ cells was also observed around the vascular lesions in the lungs of the SuHx rat model, but not in Il6 KO rats. Blockade of IL-6 signaling had an additive effect on conventional PAH therapeutics, such as endothelin receptor antagonist (macitentan) and soluble guanylyl cyclase stimulator (BAY41-2272). These findings suggest that IL-6/gp130 signaling in CD4+ cells plays a critical role in the pathogenesis of PAH.

The biased apelin receptor agonist, MM07, reverses Sugen/hypoxia-induced pulmonary arterial hypertension as effectively as the endothelin antagonist macitentan

Introduction: Pulmonary arterial hypertension (PAH) is characterised by endothelial dysfunction and pathological vascular remodelling, resulting in the occlusion of pulmonary arteries and arterioles, right ventricular hypertrophy, and eventually fatal heart failure. Targeting the apelin receptor with the novel, G protein-biased peptide agonist, MM07, is hypothesised to reverse the developed symptoms of elevated right ventricular systolic pressure and right ventricular hypertrophy. Here, the effects of MM07 were compared with the clinical standard-of-care endothelin receptor antagonist macitentan. Methods: Male Sprague-Dawley rats were randomised and treated with either normoxia/saline, or Sugen/hypoxia (SuHx) to induce an established model of PAH, before subsequent treatment with either saline, macitentan (30 mg/kg), or MM07 (10 mg/kg). Rats were then anaesthetised and catheterised for haemodynamic measurements, and tissues collected for histopathological assessment. Results: The SuHx/saline group presented with significant increases in right ventricular hypertrophy, right ventricular systolic pressure, and muscularization of pulmonary arteries compared to normoxic/saline controls. Critically, MM07 was as at least as effective as macitentan in significantly reversing detrimental structural and haemodynamic changes after 4 weeks of treatment. Discussion: These results support the development of G protein-biased apelin receptor agonists with improved pharmacokinetic profiles for use in human disease.

A single-cell atlas of lung homeostasis reveals dynamic changes during development and aging

Aging is a global challenge, marked in the lungs by function decline and structural disorders, which affects the health of the elderly population. To explore anti-aging strategies, we develop a dynamic atlas covering 45 cell types in human lungs, spanning from embryonic development to aging. We aim to apply the discoveries of lung's development to address aging-related issues. We observe that both epithelial and immune cells undergo a process of acquisition and loss of essential function as they transition from development to aging. During aging, we identify cellular phenotypic alternations that result in reduced pulmonary compliance and compromised immune homeostasis. Furthermore, we find a distinctive expression pattern of the ferritin light chain (FTL) gene, which increases during development but decreases in various types of lung cells during the aging process.

Platelet-derived microparticles and their cargos: The past, present and future

All eukaryotic cells can secrete extracellular vesicles, which have a double-membrane structure and are important players in the intercellular communication involved in a variety of important biological processes. Platelets form platelet-derived microparticles (PMPs) in response to activation, injury, or apoptosis. This review introduces the origin, pathway, and biological functions of PMPs and their importance in physiological and pathological processes. In addition, we review the potential applications of PMPs in cancer, vascular homeostasis, thrombosis, inflammation, neural regeneration, biomarkers, and drug carriers to achieve targeted drug delivery. In addition, we comprehensively report on the origin, biological functions, and applications of PMPs. The clinical transformation, high heterogeneity, future development direction, and limitations of the current research on PMPs are also discussed in depth. Evidence has revealed that PMPs play an important role in cell-cell communication, providing clues for the development of PMPs as carriers for relevant cell-targeted drugs. The development history and prospects of PMPs and their cargos are explored in this guidebook.

Mitochondrial network dynamics in pulmonary disease: Bridging the gap between inflammation, oxidative stress, and bioenergetics

Once thought of in terms of bioenergetics, mitochondria are now widely accepted as both the orchestrator of cellular health and the gatekeeper of cell death. The pulmonary disease field has performed extensive efforts to explore the role of mitochondria in regulating inflammation, cellular metabolism, apoptosis, and oxidative stress. However, a critical component of these processes needs to be more studied: mitochondrial network dynamics. Mitochondria morphologically change in response to their environment to regulate these processes through fusion, fission, and mitophagy. This allows mitochondria to adapt their function to respond to cellular requirements, a critical component in maintaining cellular homeostasis. For that reason, mitochondrial network dynamics can be considered a bridge that brings multiple cellular processes together, revealing a potential pathway for therapeutic intervention. In this review, we discuss the critical modulators of mitochondrial dynamics and how they are affected in pulmonary diseases, including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), acute lung injury (ALI), and pulmonary arterial hypertension (PAH). A dysregulated mitochondrial network plays a crucial role in lung disease pathobiology, and aberrant fission/fusion/mitophagy pathways are druggable processes that warrant further exploration. Thus, we also discuss the candidates for lung disease therapeutics that regulate mitochondrial network dynamics.

Endothelium-specific SIRT7 targeting ameliorates pulmonary hypertension through Krüpple-like factor 4 deacetylation

AIMS

Pulmonary hypertension (PH) is a pulmonary vascular disease characterized by a high mortality rate. Pulmonary arterial endothelium cells (PAECs) serve as a primary sensor of various environmental cues, such as shear stress and hypoxia, but PAEC dysfunction may trigger vascular remodelling during the onset of PH. This study aimed to illustrate the role of Sirtuin 7 (SIRT7) in endothelial dysfunction during PH and explore the potential therapeutic strategy for PH.

METHODS AND RESULTS

SIRT7 levels were measured in human and murine experimental PH samples. Bioinformatic analysis, immunoprecipitation, and deacetylation assay were used to identify the association between SIRT7 and Krüpple-like factor 4 (KLF4), a key transcription factor essential for endothelial cell (EC) homeostasis. Sugen5416 + hypoxia (SuHx)-induced PH mouse models and cell cultures were used for the study of the therapeutic effect of SIRT7 for PH. SIRT7 level was significantly reduced in lung tissues and PAECs from PH patients and the SuHx-induced PH mouse model as compared with healthy controls. Pulmonary endothelium-specific depletion of Sirt7 increased right ventricular systolic pressure and exacerbated right ventricular hypertrophy in the SuHx-induced PH model. At the molecular level, we identified KLF4 as a downstream target of SIRT7, which deacetylated KLF4 at K228 and inhibited the ubiquitination-proteasome degradation. Thus, the SIRT7/KLF4 axis maintained PAEC homeostasis by regulating proliferation, migration, and tube formation. PAEC dysfunction was reversed by adeno-associated virus type 1 vector-mediated endothelial overexpression of Sirt7 or supplementation with nicotinamide adenine dinucleotide (NAD)+ intermediate nicotinamide riboside which activated Sirt7; both approaches successfully reversed PH phenotypes.

CONCLUSION

The SIRT7/KLF4 axis ensures PAEC homeostasis, and pulmonary endothelium-specific SIRT7 targeting might constitute a PH therapeutic strategy.

Periodontitis exacerbates pulmonary hypertension by promoting IFNγ+ T cell infiltration in mice

Uncovering the risk factors of pulmonary hypertension and its mechanisms is crucial for the prevention and treatment of the disease. In the current study, we showed that experimental periodontitis, which was established by ligation of molars followed by orally smearing subgingival plaques from patients with periodontitis, exacerbated hypoxia-induced pulmonary hypertension in mice. Mechanistically, periodontitis dysregulated the pulmonary microbiota by promoting ectopic colonization and enrichment of oral bacteria in the lungs, contributing to pulmonary infiltration of interferon gamma positive (IFNγ+) T cells and aggravating the progression of pulmonary hypertension. In addition, we identified Prevotella zoogleoformans as the critical periodontitis-associated bacterium driving the exacerbation of pulmonary hypertension by periodontitis, and the exacerbation was potently ameliorated by both cervical lymph node excision and IFNγ neutralizing antibodies. Our study suggests a proof of concept that the combined prevention and treatment of periodontitis and pulmonary hypertension are necessary.

Forsythoside B Mitigates Monocrotaline-Induced Pulmonary Arterial Hypertension via Blocking the NF-κB Signaling Pathway to Attenuate Vascular Remodeling

Purpose

Pulmonary arterial hypertension (PAH) is a devastating disease with little effective treatment. The proliferation of pulmonary artery smooth muscle cells (PASMCs) induced by the nuclear factor-κB (NF-κB) signaling activation plays a pivotal role in the pathogenesis of PAH. Forsythoside B (FTS•B) possesses inhibitory effect on NF-κB signaling pathway. The present study aims to explore the effects and mechanisms of FTS•B in PAH.

Methods

Sprague-Dawley rats received monocrotaline (MCT) intraperitoneal injection to establish PAH model, and FTS•B was co-treated after MCT injection. Right ventricular hypertrophy and pulmonary artery pressure were measured by echocardiography and right heart catheterization, respectively. Histological alterations were detected by H&E staining and immunohistochemistry. FTS•B's role in PASMC proliferation and migration were evaluated by CCK-8 and wound healing assay. To investigate the underlying mechanisms, Western blotting, immunofluorescence staining and ELISA were conducted. The NF-κB activator PMA was used to investigate the role of NF-κB in FTS•B's protective effects against PAH.

Results

FTS•B markedly alleviated MCT-induced vascular remodeling and pulmonary artery pressure, and improved right ventricular hypertrophy and survival. FTS•B also reversed PDGF-BB-induced PASMC proliferation and migration, decreased PCNA and CyclinD1 expression in vitro. The elevated levels of IL-1β and IL-6 caused by MCT were decreased by FTS•B. Mechanistically, MCT-triggered phosphorylation of p65, IκBα, IKKα and IKKβ was blunted by FTS•B. FTS•B also reversed MCT-induced nuclear translocation of p65. However, all these protective effects were blocked by PMA-mediated NF-κB activation.

Conclusion

FTS•B effectively attenuates PAH by suppressing the NF-κB signaling pathway to attenuate vascular remodeling. FTS•B might be a promising drug candidate with clinical translational potential for the treatment of PAH.

Mechanistic Investigation of Calcium Channel Regulation-Associated Genes in Pulmonary Arterial Hypertension and Signatures for Diagnosis

Pulmonary arterial hypertension (PAH) is a severe cardiopulmonary disorder with complex causes. Calcium channel blockers have long been used in its treatment. Our study aimed to validate experimental results showing increased calcium ion concentration in PAH patients. We investigated the impact of genes related to calcium channel regulation on PAH development and developed an accurate diagnostic model. Clinical trial data from serum of 18 healthy individuals and 18 patients with PAH were retrospectively analyzed. Concentrations of calcium and potassium ions were determined and compared. Datasets were retrieved, selecting genes associated with calcium ion release. R packages processed the datasets, filtering 174 common genes, and conducting Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. Six hub genes were identified, and nomogram and logistic regression prediction models were constructed. Random forest filtered cross genes, and a diagnostic model was developed and validated using an artificial neural network. The 174 intersection genes related to calcium ions showed significant correlations with biological processes, cellular components, and molecular functions. Six key genes were obtained by constructing a protein-protein interaction network. A diagnostic model with high accuracy (> 90%) and diagnostic capability (AUC = 0.98) was established using a neural network algorithm. This study validated the experimental results, identified key genes associated with calcium ions, and developed a highly accurate diagnostic model using a neural network algorithm. These findings provide insights into the role of calcium release genes in PAH and demonstrate the potential of the diagnostic model for clinical application. However, due to limitations in sample size and a lack of prognosis data, the regulatory mechanisms of calcium ions in PAH patients and their impact on the clinical prognosis of PAH patients still need further exploration in the future.

Calcium sensing receptor: A promising therapeutic target in pulmonary hypertension

Pulmonary hypertension (PH) is characterized by elevation of pulmonary arterial pressure and pulmonary vascular resistance. The increased pulmonary arterial pressure and pulmonary vascular resistance due to sustained pulmonary vasoconstriction and pulmonary vascular remodeling can lead to right heart failure and eventual death. A rise in intracellular Ca2+ concentration ([Ca2+]i) and enhanced pulmonary arterial smooth muscle cells (PASMCs) proliferation contribute to pulmonary vasoconstriction and pulmonary vascular remodeling. Recent studies demonstrated that extracellular calcium sensing receptor (CaSR) as a G-protein coupled receptor participates in [Ca2+]i increase induced by hypoxia in the experimental animals of PH and in PH patients. Pharmacological blockade or gene knockout of CaSR significantly attenuates the development of PH. This review will aim to discuss and update the pathogenicity of CaSR attributed to onset and progression in PH.

Comprehensive Risk Assessment in Patients With Pulmonary Arterial Hypertension Referred for Lung Transplantation

BACKGROUND

Whether comprehensive risk assessment predicts post-referral outcome in patients with pulmonary arterial hypertension (PAH) referred for lung transplantation (LT) in Japan is unknown.Methods and Results: We retrospectively analyzed 52 PAH patients referred for LT. Risk status at referral was assessed using 3- and 4-strata models from the 2022 European Society of Cardiology and European Respiratory Society guidelines. The 3-strata model intermediate-risk group was further divided into 2 groups based on the median proportion of low-risk variables (modified risk assessment [MRA]). The primary outcome was post-referral mortality. During follow-up, 9 patients died and 13 patients underwent LT. There was no survival difference among 3-strata model groups. The 4-strata model classified 33, 16, and 3 patients as low intermediate, high intermediate, and high risk, respectively. The 4-strata model identified high-risk patients with a 1-year survival rate of 33%, but did not discriminate survival between the intermediate-risk groups. The MRA classified 15, 28, 8, and 1 patients as low, low intermediate, high intermediate, and high risk, respectively. High intermediate- or high-risk patients had worse survival (P<0.001), with 1- and 3-year survival rates of 64% and 34%, respectively. MRA high intermediate- or high-risk classification was associated with mortality (hazard ratio 12.780; 95% confidence interval 2.583-63.221; P=0.002).

CONCLUSIONS

Patients classified as high intermediate or high risk by the MRA after treatment should be referred for LT.

Expression and clinical significance of miR-8078 in patients with congenital heart disease-associated pulmonary arterial hypertension

OBJECTIVES

This study aimed to analyze the plasma levels of miR-8078 in patients with congenital heart disease-associated pulmonary arterial hypertension (CHD-PAH) and to explore the diagnostic value and potential mechanisms of miR-8078 in CHD-PAH.

METHODS

Plasma samples were collected from 110 patients with congenital heart disease. Subsequently, based on the mean pulmonary artery pressure (PAPm) measured via right heart catheterization, the patients were divided into three groups: no-PAH group (Group W, PAPm < 25 mmHg), mild group (Group M, 25 mmHg ≤ PAPm < 35 mmHg), and moderate-to-severe group (Group H, PAPm ≥ 35 mmHg). The study also involved a control group (Group C) comprised of 40 healthy individuals. The miR-8078 expression levels were determined by means of reverse transcription-polymerase chain reaction (RT-PCR). The target genes and biological functions of miR-8078 were predicted using TargetScan, PicTar, and miRDB software. Statistical analysis was performed to evaluate the correlation between miR-8078 and hemodynamic parameters in CHD-PAH, in addition to its diagnostic value.

RESULTS

The plasma miR-8078 expression levels were significantly higher in the moderate-to-severe group when compared with the control group, no-PAH group, and mild group (p < 0.05). Furthermore, the mild group and no-PAH group showed significantly higher miR-8078 expression levels when compared with the control group (p < 0.05). Both results were consistent with the high-throughput sequencing results. KEGG pathway analysis of the miR-8078 target genes revealed associations with morphine addiction, ubiquitin-mediated proteolysis, and parathyroid hormone synthesis and secretion. GO enrichment analysis indicated the involvement of miR-8078 in the regulation of transcription by RNA polymerase II, the positive regulation of stress-activated MAPK cascade, the transmembrane transport of CI- and K+ ions, chromatin organization, and atrioventricular valve morphogenesis. Correlation analysis showed that the miR-8078 expression levels were positively correlated with the pulmonary artery systolic pressure, mean pulmonary artery pressure, and pulmonary vascular resistance (correlation coefficients of 0.404, 0.397, and 0.283, respectively; all p < 0.05). Univariate and multivariate regression analyses revealed plasma miR-8078 (odds ratio: 1.475, 95 % confidence interval: 1.053-2.065, p < 0.05) to be an independent risk factor for CHD-PAH. Receiver operating characteristic curve analysis revealed that the area under the curve (AUC) for miR-8078 alone and for B-type natriuretic peptide alone in diagnosing CHD-PAH was 0.686 and 0.851, respectively, while the AUC for a combined diagnosis was 0.874, which was higher than that associated with the individual diagnoses (p < 0.05).

CONCLUSION

The findings of this study suggest that miR-8078 is upregulated in CHD-PAH, while the results of the bioinformatics analysis indicate its involvement in the pathogenesis of CHD-PAH, suggesting it to be a potential therapeutic target or biomarker.

The Construction of Three-Layered Biomimetic Arterial Graft Balances Biomechanics and Biocompatibility for Dynamic Biological Reconstruction

The process of reconstructing an arterial graft is a complex and dynamic process that is subject to the influence of various mechanical factors, including tissue regeneration and blood pressure. The attainment of favorable remodeling outcomes is contingent upon the biocompatibility and biomechanical properties of the arterial graft. A promising strategy involves the emulation of the three-layer structure of the native artery, wherein the inner layer is composed of polycaprolactone (PCL) fibers aligned with blood flow, exhibiting excellent biocompatibility that fosters endothelial cell growth and effectively prevents platelet adhesion. The middle layer, consisting of PCL and polyurethane (PU), offers mechanical support and stability by forming a contractile smooth muscle ring and antiexpansion PU network. The outer layer, composed of PCL fibers with an irregular arrangement, promotes the growth of nerves and pericytes for long-term vascular function. Prioritizing the reconstruction of the inner and outer layers establishes a stable environment for intermediate smooth muscle growth. Our three-layer arterial graft is designed to provide the blood vessel with mechanical support and stability through nondegradable PU, while the incorporation of degradable PCL generates potential spaces for tissue ingrowth, thereby transforming our graft into a living implant.

Pharmacological Agents and Potential New Therapies in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by an imbalance between vasoactive mediators, which causes vascular remodeling, increased pulmonary vascular resistance, and right ventricular overload, ultimately leading to heart failure and death. A metabolic theory has been suggested to explain the pathophysiology of PAH whereby abnormalities in mitochondrial biogenesis can trigger a hyperproliferative and apoptosis-resistant phenotype in cardiopulmonary and malignant cells, leading to mitochondrial dysfunction, which in turn causes the Warburg effect. This can culminate in the mitophagy of pulmonary vessels and cardiomyocytes. The present narrative review focuses on the pathophysiology of PAH, the pharmacological agents currently available for its treatment, and promising and challenging areas of therapeutic investigation.

The role and mechanism of AMPK in pulmonary hypertension

Pulmonary hypertension (PH) is a chronic progressive disease with high mortality. There has been more and more research focusing on the role of AMPK in PH. AMPK consists of three subunits-α, β, and γ. The crosstalk among these subunits ultimately leads to a delicate balance to affect PH, which results in conflicting conclusions about the role of AMPK in PH. It is still unclear how these subunits interfere with each other and achieve balance to improve or deteriorate PH. Several signaling pathways are related to AMPK in the treatment of PH, including AMPK/eNOS/NO pathway, Nox4/mTORC2/AMPK pathway, AMPK/BMP/Smad pathway, and SIRT3-AMPK pathway. Among these pathways, the role and mechanism of AMPK/eNOS/NO and Nox4/mTORC2/AMPK pathways are clearer than others, while the SIRT3-AMPK pathway remains still unclear in the treatment of PH. There are drugs targeting AMPK to improve PH, such as metformin (MET), MET combination, and rhodiola extract. In addition, several novel factors target AMPK for improving PH, such as ADAMTS8, TUFM, and Salt-inducible kinases. However, more researches are needed to explore the specific AMPK signaling pathways involved in these novel factors in the future. In conclusion, AMPK plays an important role in PH.

Modulating NO-GC Pathway in Pulmonary Arterial Hypertension

The pathogenesis of complex diseases such as pulmonary arterial hypertension (PAH) is entirely rooted in changes in the expression of some vasoactive factors. These play a significant role in the onset and progression of the disease. Indeed, PAH has been associated with pathophysiologic alterations in vascular function. These are often dictated by increased oxidative stress and impaired modulation of the nitric oxide (NO) pathway. NO reduces the uncontrolled proliferation of vascular smooth muscle cells that leads to occlusion of vessels and an increase in pulmonary vascular resistances, which is the mainstay of PAH development. To date, two classes of NO-pathway modulating drugs are approved for the treatment of PAH: the phosphodiesterase-5 inhibitors (PD5i), sildenafil and tadalafil, and the soluble guanylate cyclase activator (sGC), riociguat. Both drugs provide considerable improvement in exercise capacity and pulmonary hemodynamics. PD5i are the recommended drugs for first-line PAH treatment, whereas sGCs are also the only drug approved for the treatment of resistant or inoperable chronic thromboembolic pulmonary hypertension. In this review, we will focus on the current information regarding the nitric oxide pathway and its modulation in PAH.

Cyclin D-CDK4 Disulfide Bond Attenuates Pulmonary Vascular Cell Proliferation

BACKGROUND

Pulmonary hypertension (PH) is a chronic vascular disease characterized, among other abnormalities, by hyperproliferative smooth muscle cells and a perturbed cellular redox and metabolic balance. Oxidants induce cell cycle arrest to halt proliferation; however, little is known about the redox-regulated effector proteins that mediate these processes. Here, we report a novel kinase-inhibitory disulfide bond in cyclin D-CDK4 (cyclin-dependent kinase 4) and investigate its role in cell proliferation and PH.

METHODS

Oxidative modifications of cyclin D-CDK4 were detected in human pulmonary arterial smooth muscle cells and human pulmonary arterial endothelial cells. Site-directed mutagenesis, tandem mass-spectrometry, cell-based experiments, in vitro kinase activity assays, in silico structural modeling, and a novel redox-dead constitutive knock-in mouse were utilized to investigate the nature and definitively establish the importance of CDK4 cysteine modification in pulmonary vascular cell proliferation. Furthermore, the cyclin D-CDK4 oxidation was assessed in vivo in the pulmonary arteries and isolated human pulmonary arterial smooth muscle cells of patients with pulmonary arterial hypertension and in 3 preclinical models of PH.

RESULTS

Cyclin D-CDK4 forms a reversible oxidant-induced heterodimeric disulfide dimer between C7/8 and C135, respectively, in cells in vitro and in pulmonary arteries in vivo to inhibit cyclin D-CDK4 kinase activity, decrease Rb (retinoblastoma) protein phosphorylation, and induce cell cycle arrest. Mutation of CDK4 C135 causes a kinase-impaired phenotype, which decreases cell proliferation rate and alleviates disease phenotype in an experimental mouse PH model, suggesting this cysteine is indispensable for cyclin D-CDK4 kinase activity. Pulmonary arteries and human pulmonary arterial smooth muscle cells from patients with pulmonary arterial hypertension display a decreased level of CDK4 disulfide, consistent with CDK4 being hyperactive in human pulmonary arterial hypertension. Furthermore, auranofin treatment, which induces the cyclin D-CDK4 disulfide, attenuates disease severity in experimental PH models by mitigating pulmonary vascular remodeling.

CONCLUSIONS

A novel disulfide bond in cyclin D-CDK4 acts as a rapid switch to inhibit kinase activity and halt cell proliferation. This oxidative modification forms at a critical cysteine residue, which is unique to CDK4, offering the potential for the design of a selective covalent inhibitor predicted to be beneficial in PH.

Extracellular vesicles in venous thromboembolism and pulmonary hypertension

Venous thromboembolism (VTE) is a multifactorial disease, and pulmonary hypertension (PH) is a serious condition characterized by pulmonary vascular remodeling leading with increased pulmonary vascular resistance, ultimately leading to right heart failure and death. Although VTE and PH have distinct primary etiologies, they share some pathophysiologic similarities such as dysfunctional vasculature and thrombosis. In both conditions there is solid evidence that EVs derived from a variety of cell types including platelets, monocytes, endothelial cells and smooth muscle cells contribute to vascular endothelial dysfunction, inflammation, thrombosis, cellular activation and communications. However, the roles and importance of EVs substantially differ between studies depending on experimental conditions and parent cell origins of EVs that modify the nature of their cargo. Numerous studies have confirmed that EVs contribute to the pathophysiology of VTE and PH and increased levels of various EVs in relation with the severity of VTE and PH, confirming its potential pathophysiological role and its utility as a biomarker of disease severity and as potential therapeutic targets.

Inhibition of Hsp110-STAT3 interaction in endothelial cells alleviates vascular remodeling in hypoxic pulmonary arterial Hypertension model

BACKGROUND

Pulmonary arterial hypertension (PAH) is a progressive and devastating disease characterized by pulmonary vascular remodeling which is associated with the malignant phenotypes of pulmonary vascular cells. Recently, the effects of heat shock protein 110 (Hsp110) in human arterial smooth muscle cells were reported. However, the underlying roles and mechanisms of Hsp110 in human pulmonary arterial endothelial cells (HPAECs) that was disordered firstly at the early stage of PAH remain unknown.

METHODS

In this research, the expression of Hsp110 in PAH human patients and rat models was investigated, and the Hsp110 localization was determined both in vivo and in vitro. The roles and mechanism of elevated Hsp110 in excessive cell proliferation and migration of HPAECs were assessed respectively exposed to hypoxia. Small molecule inhibitors targeting Hsp110-STAT3 interaction were screened via fluorescence polarization, anti-aggregation and western blot assays. Moreover, the effects of compound 6 on HPAECs abnormal phenotypes in vitro and pulmonary vascular remodeling of hypoxia-indued PAH rats in vivo by interrupting Hsp110-STAT3 interaction were evaluated.

RESULTS

Our studies demonstrated that Hsp110 expression was increased in the serum of patients with PAH, as well as in the lungs and pulmonary arteries of PAH rats, when compared to their respective healthy subjects. Moreover, Hsp110 levels were significantly elevated in HPAECs under hypoxia and mediated its aberrant phenotypes. Furthermore, boosted Hsp110-STAT3 interaction resulted in abnormal proliferation and migration via elevating p-STAT3 and c-Myc in HPAECs. Notably, we successfully identified compound 6 as potent Hsp110-STAT3 interaction inhibitor, which effectively inhibited HPAECs proliferation and migration, and significantly ameliorated right heart hypertrophy and vascular remodeling of rats with PAH.

CONCLUSIONS

Our studies suggest that elevated Hsp110 plays a vital role in HPAECs and inhibition of the Hsp110-STAT3 interaction is a novel strategy for improving vascular remodeling. In addition, compound 6 could serve as a promising lead compound for developing first-in-class drugs against PAH.

The Emerging Therapeutic Role of Prostaglandin E2 Signaling in Pulmonary Hypertension

Mild-to-moderate pulmonary hypertension (PH) is a common complication of chronic obstructive pulmonary disease (COPD). It is characterized by narrowing and thickening of the pulmonary arteries, resulting in increased pulmonary vascular resistance (PVR) and ultimately leading to right ventricular dysfunction. Pulmonary vascular remodeling in COPD is the main reason for the increase of pulmonary artery pressure (PAP). The pathogenesis of PH in COPD is complex and multifactorial, involving chronic inflammation, hypoxia, and oxidative stress. To date, prostacyclin and its analogues are widely used to prevent PH progression in clinical. These drugs have potent anti-proliferative, anti-inflammatory, and stimulating endothelial regeneration properties, bringing therapeutic benefits to the slowing, stabilization, and even some reversal of vascular remodeling. As another well-known and extensively researched prostaglandins, prostaglandin E2 (PGE2) and its downstream signaling have been found to play an important role in various biological processes. Emerging evidence has revealed that PGE2 and its receptors (i.e., EP1-4) are involved in the regulation of pulmonary vascular homeostasis and remodeling. This review focuses on the research progress of the PGE2 signaling pathway in PH and discusses the possibility of treating PH based on the PGE2 signaling pathway.

Superoxide-Mediated Upregulation of MMP9 Participates in BMPR2 Destabilization and Pulmonary Hypertension Development

BACKGROUND AND AIMS

we previously reported in studies on organoid-cultured bovine pulmonary arteries that pulmonary hypertension (PH) conditions of exposure to hypoxia or endothelin-1 caused a loss of a cartilage oligomeric matrix protein (COMP) stabilization of bone morphogenetic protein receptor-2 (BMPR2) function, a known key process contributing to pulmonary hypertension development. Based on subsequent findings, these conditions were associated with an extracellular superoxide-mediated increase in matrix metalloproteinase 9 (MMP-9) expression. We investigated if this contributed to PH development using mice deficient in MMP9.

RESULTS

wild-type (WT) mice exposed to Sugen/Hypoxia (SuHx) to induce PH had increased levels of MMP9 in their lungs. Hemodynamic measures from MMP9 knockout mice (MMP9 KO) indicated they had attenuated PH parameters compared to WT mice based on an ECHO assessment of pulmonary artery pressure, right ventricular systolic pressure, and Fulton index hypertrophy measurements. In vitro vascular reactivity studies showed impaired endothelium-dependent and endothelium-independent NO-associated vasodilatory responses in the pulmonary arteries of SuHx mice and decreased lung levels of COMP and BMPR2 expression. These changes were attenuated in MMP9 KO mice potentially through preserving COMP-dependent stabilization of BMPR2.

INNOVATION

this study supports a new function of superoxide in increasing MMP9 and the associated impairment of BMPR2 in promoting PH development which could be a target for future therapies.

CONCLUSION

superoxide, through promoting increases in MMP9, mediates BMPR2 depletion and its consequent control of vascular function in response to PH mediators and the SuHx mouse model of PH.

Untangling the mechanisms of pulmonary arterial hypertension-induced right ventricular stiffening in a large animal model

Pulmonary hypertension (PHT) is a devastating disease with low survival rates. In PHT, chronic pressure overload leads to right ventricle (RV) stiffening; thus, impeding diastolic filling. Multiple mechanisms may contribute to RV stiffening, including wall thickening, microstructural disorganization, and myocardial stiffening. The relative importance of each mechanism is unclear. Our objective is to use a large animal model to untangle these mechanisms. Thus, we induced pulmonary arterial hypertension (PAH) in sheep via pulmonary artery banding. After eight weeks, the hearts underwent anatomic and diffusion tensor MRI to characterize wall thickening and microstructural disorganization. Additionally, myocardial samples underwent histological and gene expression analyses to quantify compositional changes and mechanical testing to quantify myocardial stiffening. Finally, we used finite element modeling to disentangle the relative importance of each stiffening mechanism. We found that the RVs of PAH animals thickened most at the base and the free wall and that PAH induced excessive collagen synthesis, increased cardiomyocyte cross-sectional area, and led to microstructural disorganization, consistent with increased expression of fibrotic genes. We also found that the myocardium itself stiffened significantly. Importantly, myocardial stiffening correlated significantly with collagen synthesis. Finally, our computational models predicted that myocardial stiffness contributes to RV stiffening significantly more than other mechanisms. Thus, myocardial stiffening may be the most important predictor for PAH progression. Given the correlation between myocardial stiffness and collagen synthesis, collagen-sensitive imaging modalities may be useful for estimating myocardial stiffness and predicting PAH outcomes. STATEMENT OF SIGNIFICANCE: Ventricular stiffening is a significant contributor to pulmonary hypertension-induced right heart failure. However, the mechanisms that lead to ventricular stiffening are not fully understood. The novelty of our work lies in answering this question through the use of a large animal model in combination with spatially- and directionally sensitive experimental techniques. We find that myocardial stiffness is the primary mechanism that leads to ventricular stiffening. Clinically, this knowledge may be used to improve diagnostic, prognostic, and therapeutic strategies for patients with pulmonary hypertension.

RNA modification in cardiovascular disease: implications for therapeutic interventions

Cardiovascular disease (CVD) is the leading cause of death in the world, with a high incidence and a youth-oriented tendency. RNA modification is ubiquitous and indispensable in cell, maintaining cell homeostasis and function by dynamically regulating gene expression. Accumulating evidence has revealed the role of aberrant gene expression in CVD caused by dysregulated RNA modification. In this review, we focus on nine common RNA modifications: N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N4-acetylcytosine (ac4C), pseudouridine (Ψ), uridylation, adenosine-to-inosine (A-to-I) RNA editing, and modifications of U34 on tRNA wobble. We summarize the key regulators of RNA modification and their effects on gene expression, such as RNA splicing, maturation, transport, stability, and translation. Then, based on the classification of CVD, the mechanisms by which the disease occurs and progresses through RNA modifications are discussed. Potential therapeutic strategies, such as gene therapy, are reviewed based on these mechanisms. Herein, some of the CVD (such as stroke and peripheral vascular disease) are not included due to the limited availability of literature. Finally, the prospective applications and challenges of RNA modification in CVD are discussed for the purpose of facilitating clinical translation. Moreover, we look forward to more studies exploring the mechanisms and roles of RNA modification in CVD in the future, as there are substantial uncultivated areas to be explored.

Preventive effect of LCZ696 on hypoxic pulmonary hypertension in rats via regulating the PI3K/AKT signaling pathway

Hypoxic pulmonary hypertension (HPH) is a devastating disease worldwide; however, effective therapeutic drugs are lacking. This study investigated the effects and underlying mechanisms of LCZ696 treatment on hypoxia-induced pulmonary hypertension. Male Sprague-Dawley (SD) rats were kept in a hypobaric chamber with an oxygen concentration of 5% for 4 weeks. Rats were treated with either LCZ696 (18 mg/kg, 36 mg/kg, and 72 mg/kg) or sildenafil. The mean pulmonary artery pressure (mPAP), right ventricle hypertrophy index (RVHI), and lung system index were measured. Hematoxylin-eosin (HE) staining, Masson staining, and immunofluorescence staining were used for histological analysis. Enzyme linked immunosorbent assay (ELISA) kits were used to determine the concentrations of inflammatory and hypoxia-related factors. Western blotting was used to examine the expression of apoptotic and PI3K/AKT signaling pathway proteins in rat lung tissue. Hypoxia increased mPAP, RVHI, and lung system index and induced pulmonary vascular remodeling, pulmonary arteriomyosis, and pulmonary artery fibrosis. LCZ696 treatment reduced the increase in mPAP, RVHI, and the lung system index and ameliorated the induced pathological changes. Hypoxia upregulated expression of NF-kB, TNF-α, IL-6, HIF-1α, and Vascular endothelial growth factor (VEGF), decreased the ratio of Bax/Bcl-2, and activated the PI3K/AKT signaling pathway in lung tissue, and these effects were partially reversed by treatment with LCZ696. These results demonstrated that LCZ696 can ameliorate hypoxia-induced HPH by suppressing apoptosis, inhibiting the inflammatory response, and inhibiting the PI3K/AKT signaling pathway. It provides a reference for clinical rational drug use and lays a foundation for the study of HPH therapeutic drugs.

Pulmonary Hypertension: Unveiling Molecular Mechanisms, Diagnosis, and Therapeutic Targets

Pulmonary hypertension (PH) is a progressive and life-threatening disease characterized by increased pulmonary arterial pressure, which leads to right heart hypertrophy and eventually right heart failure [...].