Pathogenesis Of Pulmonary Hypertension Research Articles

5-Methylcytosine-modified circRNA-CCNL2 regulates vascular remdeling in hypoxic pulmonary hypertension through binding to FXR2.

Pulmonary hypertension (PH) is a malignant cardiovascular disease with a complex etiology. 5-Methylcytosine (m5C) is a post-transcriptional RNA modification identified in both stable and highly abundant RNAs, with a lower frequency of occurrence in circular RNAs (circRNAs). Nevertheless, the function of m5C-modified circRNAs in the pathogenesis of PH remains uncertain. The objective of this study was to investigate the biological role and molecular mechanisms of m5C-modified circRNA-CCNL2 in hypoxic PH pulmonary vascular remodeling. Our findings revealed that hypoxia downregulates circCCNL2 expression, and overexpression of circCCNL2 attenuates PH progression and inhibits the proliferation of pulmonary artery smooth muscle cell (PASMCs). Bioinformatics predictions indicated the presence of m5C modification sites in circCCNL2, which NSUN2 mediated. The downregulation of NSUN2 resulted in a reduction in m5C modification of circCCNL2. It was also observed that the stability of circRNAs was associated with the proliferation of PASMCs. From a mechanistic standpoint, low expression of circCCNL2 resulted in reduced binding of FXR2, while increased association of free FXR2 with CDKL3 led to enhanced proliferation of PASMCs. Notably, circCCNL2 expression was found to be regulated by alternative splicing involving SRSF2, with reduced pre-CCNL2 splicing resulting from low SRSF2 expression, ultimately leading to decreased circCCNL2 expression. This is the first demonstration that m5C-modified circCCNL2 can slow the development of PH and inhibit the proliferation of PASMCs by binding to FXR2. These findings offer new insights into the regulation of circRNAs through m5C modifications and the role of epigenetic reprogramming in PH.

Lung Endothelial Cell Heterogeneity in Health and Pulmonary Vascular Disease.

Lung endothelial cells (ECs) are essential for maintaining organ function and homeostasis. Despite sharing some common features with ECs from organ systems, lung ECs exhibit significant heterogeneity in morphology, function, and gene expression. This heterogeneity is increasingly recognized as a key contributor to the development of pulmonary diseases like pulmonary hypertension (PH). In this mini-review, we explore the evolving understanding of lung EC heterogeneity, particularly through the lens of single-cell RNA sequencing (scRNA-seq) technologies. These advances have provided unprecedented insights into the diverse EC subpopulations, their specific roles, and the disturbances in their homeostatic functions that contribute to PH pathogenesis. In particular, these studies identified novel and functionally distinct cell types such as aerocytes and general capillary ECs that are critical for maintaining lung function in health and disease. In addition, multiple novel pathways and mechanisms have been identified that contribute to aberrant pulmonary vascular remodeling in PH. Emerging techniques like single-nucleus RNA sequencing and spatial transcriptomics have further pushed the field forward by discovering novel disease mediators. As research continues to leverage these advanced techniques, the field is poised to uncover novel EC subtypes and disease mechanisms, paving the way for new therapeutic targets in PH and other lung diseases.

Noncoding RNA Lipotherapeutics: A Promising Breakthrough in Pulmonary Hypertension Treatment.

Pulmonary Hypertension (PH) is a complex cardiovascular disorder characterized by elevated blood pressure in the pulmonary arteries. Current therapeutic approaches for PH have limitations in addressing the underlying molecular mechanisms. This article explores the potential of noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), delivered through Lipid-Based Nanoparticles (LNPs) as a novel treatment strategy. These ncRNAs play critical roles in regulating vascular function and are implicated in PH pathogenesis. LNPs provide a promising method for the efficient and targeted delivery of ncRNAs. Advances in LNP technology, including the incorporation of R8 peptide modification, have shown promise in enhancing the delivery and efficacy of ncRNAs in PH models. Challenges such as biocompatibility, toxicity, and precise targeting must be addressed as these therapies move toward clinical application. The potential of personalized medicine and the integration of artificial intelligence in LNP design are discussed as prospects. In conclusion, ncRNA lipotherapeutics delivered via LNPs offer a transformative approach to treating PH, potentially leading to more effective management and improved patient outcomes in the future. However, continued research and clinical trials are necessary to fully realize their therapeutic potential in the field of PH treatment.

Oral administration of pioglitazone inhibits pulmonary hypertension by regulating the gut microbiome and plasma metabolome in male rats.

The oral administrated thiazolidinediones (TZDs) have been widely reported to alleviate experimental pulmonary hypertension (PH). However, previous studies mainly focused on their beneficial effects on the cardiopulmonary vascular system but failed to determine their potential roles on gut microenvironment. This study aims to investigate the effects of pioglitazone, an oral TZD drug, on gut microbiome in classic PH rat models induced by hypoxia (HPH) or SU5416/hypoxia (SuHx-PH) and evaluate the therapeutic potential of supplementation of selective probiotics for experimental PH. Pioglitazone remarkably inhibited the PH pathogenesis in both models and reshaped the gut microbiome and plasma metabolome. Correlation analyses represented strong and unique association between the protective metabolites and bacteria genera (Roseburia, Lactobacillus, and Streptococcus) that were positively stimulated by pioglitazone. Supplementation of selective probiotics Roseburia intestinalis (R. intestinalis) partially attenuated SuHx-PH and rebuilt a novel gut microbiome and host metabolome. This study reports for the first time that oral administration of pioglitazone protects PH by regulating the gut microbiome and host metabolome, providing novel insights for the TZD drugs. The data also supports that modulation of gut microbiota by supplementation of selective probiotics could be a novel effective therapeutic strategy for the treatment of PH.

Nbeal2 Knockout Mice Are Not Protected Against Hypoxia-Induced Pulmonary Vascular Remodeling and Pulmonary Hypertension.

Inflammation drives the initiation and progression of pulmonary hypertension (PH). Platelets, increasingly recognized as immune cells, are activated and increased in the lungs of patients with PH. Platelet activation leads to the release of α-granule chemokines, many of which are implicated in PH. We hypothesized that hypoxia-induced secretion of platelet α-granule stored proteins and PH would be prevented in Nbeal2 -/-, α-granule deficient mice. WT and Nbeal2 -/- mice were maintained in normoxia or exposed to 10% hypobaric hypoxia for 3, 14, 21, or 35 days. We observed macrothrombocytopenia, increased circulating neutrophils and monocytes, and increased lung interstitial macrophages in Nbeal2 -/- mice at baseline. Hypoxia-induced platelet activation was attenuated, and hypoxia-induced increase in lung PF4 and platelets was delayed in Nbeal2 -/- mice compared to WT mice. Finally, although pulmonary vascular remodeling (PVR) and PH were attenuated at day 21, Nbeal2 -/- mice were not protected against hypoxia-induced PVR and PH at day 35. While this mutation also impacted circulating monocytes, neutrophils, and lung IMs, all of which are critical in the development of experimental PH, we gained further support for the role of platelets and α-granule proteins, such as PF4, in PH progression and pathogenesis and made several observations that expand our understanding of α-granule deficient mice in chronic hypoxia.

Endothelial FUNDC1 Deficiency Drives Pulmonary Hypertension.

Pulmonary hypertension (PH) is associated with endothelial dysfunction. However, the cause of endothelial dysfunction and its impact on PH remain incompletely understood. We aimed to investigate whether the hypoxia-inducible FUNDC1 (FUN14 domain-containing 1)-dependent mitophagy pathway underlies PH pathogenesis and progression. We first analyzed FUNDC1 protein levels in lung samples from patients with PH and animal models. Using rodent PH models induced by HySu (hypoxia+SU5416) or chronic hypoxia, we further investigated PH pathogenesis and development in response to global and cell-type-specific Fundc1 loss/gain-of-function. We also investigated the spontaneous PH in mice with inducible loss of endothelial Fundc1. In addition, histological, metabolic, and transcriptomic studies were performed to delineate molecular mechanisms. Finally, findings were validated in vivo by compound deficiency of HIF2α (hypoxia-inducible factor 2α; Epas1) and pharmacological intervention. FUNDC1 protein levels were reduced in PH lung vessels from clinical subjects and animal models. Global Fundc1 deficiency exacerbated PH, while its overexpression is protective. The effect of FUNDC1 was mediated by endothelial cells rather than smooth muscle cells. Further, inducible loss of endothelial Fundc1 in postnatal mice was sufficient to cause PH spontaneously, whereas augmenting endothelial Fundc1 protected against PH before and after the onset of disease. Mechanistically, Fundc1 deficiency impaired basal mitophagy in endothelial cells, leading to the accumulation of dysfunctional mitochondria, metabolic reprogramming toward aerobic glycolysis, pseudohypoxia, and senescence, likely via a mtROS-HIF2α signaling pathway. Subsequently, Fundc1-deficient endothelial cells increased IGFBP2 (insulin-like growth factor-binding protein 2) secretion that drove pulmonary arterial remodeling to instigate PH. Finally, proof-of-principle in vivo studies showed significant efficacy on PH amelioration by targeting endothelial mitophagy, pseudohypoxia, senescence, or IGFBP2. Collectively, we show that FUNDC1-mediated basal mitophagy is critical for endothelial homeostasis, and its disruption instigates PH pathogenesis. Given that similar changes in FUNDC1 and IGFBP2 were observed in PH patients, our findings are of significant clinical relevance and provide novel therapeutic strategies for PH.

MMP8-mediated vascular remodeling in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a vascular remodeling disease that impacts the cardiopulmonary system. Due to the currently limited understanding of vascular remodeling, a cure for PAH remains elusive. This study highlights the critical role of the STAT1 (signal transducer and activator of transcription 1)/MMP8 (matrix metallopeptidase 8)/DRP1 (dynamin-related protein 1) axis in vascular remodeling and the pathogenesis of pulmonary hypertension. Notably, MMP8 is significantly elevated in pulmonary arterial endothelial cells and its levels correlate with the severity of the disease. MMP8 binds to and activates DRP1, inducing mitochondrial fragmentation and promoting a malignant phenotype of endothelial cells under hypoxic conditions. Moreover, MMP8 is tightly regulated by STAT1. The knockout of MMP8 attenuates chronic pulmonary vascular remodeling, and drugs targeting MMP8 alleviate pulmonary hypertension and enhance cardiac function. This study offers fresh insights into hypoxia-induced vascular remodeling, laying a theoretical foundation for countering vascular remodeling by directly regulating the STAT1/MMP8/DRP1 axis.

Deciphering the inhibitory effects of trimetazidine on pulmonary hypertension development via decreasing fatty acid oxidation and promoting glucose oxidation

Pulmonary hypertension (PH) is a devastating disease characterized by vascular remodeling, resulting in right ventricular failure and death. Dysregulation of energy metabolism is linked to PH pathogenesis. Trimetazidine (TMZ), a selective long-chain 3-ketoacyl coenzyme A thiolase inhibitor, is critical in maintaining energy metabolism. Despite the indicated TMZ’s inhibitory effect on pulmonary vascular remodeling in PH development, the integrated evaluation of the changes in biomolecules, such as metabolites and transcripts, that TMZ induces in the lung and heart tissues is largely unknown in vivo. For an improved understanding of the molecular mechanism involving the effects of TMZ on PH development, we performed a comprehensive analysis of the changes in cardiac metabolites and pulmonary transcripts of SU5416-Hypoxia (Su/Hx) rats treated with TMZ. Metabolomic analysis of the Su/Hx-induced PH hearts demonstrated that TMZ reduced the long-chain fatty acid concentration. Additionally, TMZ alleviated PH degree and excessive strain on the right heart functions in rats with Su/Hx-induced PH. We identified the candidate target genes for TMZ treatment during PH development. Interestingly, the mRNA levels of the fatty acid transporters were substantially downregulated by TMZ administration in the lungs with Su/Hx-induced PH. Notably, TMZ suppressed excessive proliferation of human pulmonary artery smooth muscle cells under hypoxic conditions. Our study suggests that TMZ ameliorates PH development by involving energy metabolism in the lungs and heart.

A bovine model of hypoxia-induced pulmonary hypertension reveals a gradient of immune and matrisome response with a complement signature found in circulation.

Pulmonary hypertension (PH) is a progressive vascular disease characterized by vascular remodeling, stiffening, and luminal obstruction, driven by dysregulated cell proliferation, inflammation, and extracellular matrix (ECM) alterations. Despite the recognized contribution of ECM dysregulation to PH pathogenesis, the precise molecular alterations in the matrisome remain poorly understood. In this study, we employed a matrisome-focused proteomics approach to map the protein composition in a young bovine calf model of acute hypoxia-induced PH. Our findings reveal distinct alterations in the matrisome along the pulmonary vascular axis, with the most prominent changes observed in the main pulmonary artery. Key alterations included a strong immune response and wound repair signature, characterized by increased levels of complement components, coagulation cascade proteins, and provisional matrix markers. In addition, we observed upregulation of ECM-modifying enzymes, growth factors, and core ECM proteins implicated in vascular stiffening, such as collagens, periostin, tenascin-C, and fibrin(ogen). Notably, these alterations correlated with increased mean pulmonary arterial pressure and vascular remodeling. In the plasma, we identified increased levels of complement components, indicating a systemic inflammatory response accompanying the vascular remodeling. Our findings shed light on the dynamic matrisome remodeling in early-stage PH, implicating a wound-healing trajectory with distinct patterns from the main pulmonary artery to the distal vasculature. This study provides novel insights into the immune cell infiltration and matrisome alterations associated with PH pathogenesis and highlights potential biomarkers and therapeutic targets within the matrisome landscape.NEW & NOTEWORTHY Extensive immune cell infiltration and matrisome alterations associated with hypoxia-induced pulmonary hypertension in a large mammal model. Matrisome components correlate with increased resistance to identify candidate alterations that drive biomechanical manifestations of the disease.

Idiopathic pulmonary hypertension in an adult with patent foramen ovale

The article is devoted to the clinical case of combined idiopathic pulmonary hypertension with an open foramen ovale of the atrial septum in a young man of 21 years old with progressive decrease in lung ventilation function. The relationship of pulmonary arterial hypertension with an open foramen ovale of the atrial septum is nearly not described in the literature, as it is rarely found in clinical practice. According to the classification, pulmonary hypertension is divided into idiopathic (primary), secondary and pulmonary hypertension caused by other causes. In the pathogenesis of any PAH, an important role belongs to a complex of vascular changes. Verification of vascular changes is carried out histologically. Variants of idiopathic pulmonary hypertension are plexiform and thrombotic arteriopathy, veno-occlusive disease, capillary hemangiomatosis. An open foramen ovale as a structural anomaly of the adult heart (a vestige of embryonic blood circulation) causes a variety of hemodynamic disorders that can affect the pathogenesis of pulmonary hypertension. Because of this, preclinical observation of a combination of plexiform and thrombotic arteriopathy with a patent foramen ovale of the interatrial septum in a young man of 21 years old and an attempt to determine the role of an open oval window in the progression of pulmonary hypertension and its effect on treatment is of interest. The diagnosis of idiopathic pulmonary hypertension was made based on the clinical picture, laboratory parameters, echocardiography and histological examination of pulmonary vessels. The article discusses the importance of a patent foramen ovale in the pathogenesis of idiopathic pulmonary hypertension.

Nr1d1 inhibition mitigates intermittent hypoxia-induced pulmonary hypertension via Dusp1-mediated Erk1/2 deactivation and mitochondrial fission attenuation

Intermittent hypoxia (IH) precipitates pulmonary vasoconstriction, culminating in the onset of pulmonary hypertension (PH) among individuals afflicted with sleep apnea. While Nuclear receptor subfamily 1 group D member 1 (Nr1d1) is progressively recognized as pivotal regulator of cellular physiology, the role in the pathogenesis of IH-induced PH remains largely uncharted. The expression of Nr1d1 was examined in IH-induced rodent PH and in IH-treated PASMCs. To elucidate the contribution of Nr1d1 to the development of IH-induced PH, we employed siRNA to modulate Nr1d1 expression in vitro and employed serotype 1 adeno-associated virus (AAV1) in vivo. Nr1d1 levels were elevated in IH-induced rodents PH lung tissues and IH-treated PASMCs. Knocking down Nr1d1 by AAV1 effectively inhibited PH progression in chronic IH-induced PH models. Mechanistic investigations identified dual specificity phosphatase 1 (Dusp1), as a direct target that Nr1d1 trans-repressed, mediating Nr1d1’s regulatory influence on Erk1/2/Drp1 signaling. Nr1d1 deficiency ameliorates mitochondrial dysfunction and fission by restoring Dusp1 dysregulation and Drp1 phosphorylation. Activation of Erk1/2 with PMA reversed the Dusp1-mediated regulation of Drp1 phosphorylation, indicating the involvement of the Erk1/2 pathway in Drp1 phosphorylation controlled by Dusp1. Meanwhile, intermittent hypoxia induced more severe PH in Dusp1 knockout mice compared with wild-type mice. Our data unveil a novel role for Nr1d1 in IH-induced PH pathogenesis and an undisclosed Nr1d1-Dusp1 axis in PASMCs mitochondrial fission regulation.

The causes of pulmonary hypertension and the benefits of aerobic exercise for pulmonary hypertension from an integrated perspective.

Pulmonary hypertension is a progressive disease of the pulmonary arteries that begins with increased pulmonary artery pressure, driven by progressive remodeling of the small pulmonary arteries, and ultimately leads to right heart failure and death. Vascular remodeling is the main pathological feature of pulmonary hypertension, but treatments for pulmonary hypertension are lacking. Determining the process of vascular proliferation and dysfunction may be a way to decipher the pathogenesis of pulmonary hypertension. In this review, we summarize the important pathways of pulmonary hypertension pathogenesis. We show how these processes are integrated and emphasize the benign role of aerobic exercise, which, as an adjunctive therapy, may be able to modify vascular remodeling in pulmonary hypertension.

Investigating the causal relationship between human blood metabolites and pulmonary hypertension: a two-sample Mendelian randomization study.

Several recent investigations have posited that distinct metabolites in the bloodstream may be correlated with the pathogenesis of Pulmonary Hypertension (PH). Nonetheless, the interrelationship between the pathogenesis of PH and metabolite fluctuations remains incompletely elucidated, and findings may differ across studies. In the extant research, data from 486 metabolite-and PH-related genetic variants in human subjects were procured based on Genome-Wide Association Studies (GWAS) and Finnish databases. Univariate Mendelian Randomization analyses were deployed to evaluate the causal relationships between them. The utilization of the randomized Inverse Variance weighted(IVW) method served as the primary analytic framework in this Mendelian Randomization (MR) study. Additionally, four alternative computational strategies, encompassing MR-Egger, were employed as auxiliary methods. A myriad of tests, including Cochran's Q Test, MR-Egger intercept test, MR-PRESSO, leave-one-out analysis, and linkage disequilibrium score were incorporated to assess the robustness of the study outcomes. Metabolite pathway analysis was also executed to identify potential metabolic pathways. After a series of validations and corrected for False discovery rate (FDR), we found a significant association between 1,5-anhydroglucitol (OR = 2.00, 95% CI: 1.39-2.89, P = 0.0002) and PH, and a significant association between pyridoxalate (OR = 0.59, 95% CI: 0.43-0.81, P = 0.0009) and 1-a achidonoylglycerophosphocholine (OR = 1.78, 95% CI: 1.22-2.58, P = 0.0026) had a suggested association with PH. In addition, the vitamin B6 metabolic pathway was also determined to be associated with PH. Conclusively, we isolated 1,5-anhydroglucitol, 1-arachidonoylglycerophosphocholine, and pyridoxate as causally implicated in PH, thereby proffering substantial theoretical substantiation for the formulation of future PH prevention and screening paradigms.

PPARγ/ETV2 axis regulates endothelial-to-mesenchymal transition in pulmonary hypertension.

Endothelial-to-mesenchymal transition (EndoMT) plays an important role in pulmonary hypertension (PH) but the molecular mechanisms regulating EndoMT remain to be defined. We demonstrate that the axis of the transcription factors PPARγ (Peroxisome Proliferator-Activated Receptor gamma) and ETV2 (ETS variant 2) play important roles in the pathogenesis of PH. Decreased levels of the expression of PPARγ and ETV2 along with reduced endothelial and increased EndoMT markers are consistently observed in lungs and pulmonary artery endothelial cells (PAECs) of idiopathic pulmonary arterial hypertension patients, in hypoxia-exposed mouse lungs, human PAECs, and in induced-EndoMT cells. Etv2 +/- mice spontaneously developed PH and right ventricular hypertrophy (RVH), associated with increased EndoMT markers and decreased EC markers. Interestingly, chronic hypoxia exacerbated right ventricular systolic pressure and RVH in Etv2 +/- mice. PPARγ transcriptionally activates the ETV2 promoter. Consistently, while mice overexpressing endothelial PPARγ increases the expression of ETV2 and endothelial markers with reduced EndoMT markers, endothelial PPARγ KO mice show decreased ETV2 expression and enhanced EndoMT markers. Inducible overexpression of ETV2 under induced-EndoMT cell model reduces number of cells with mesenchymal morphology and decreases expression of mesenchymal markers with increased EC makers, compared to control. Therefore, our study suggests that PPARγ-ETV2 signaling regulates PH pathogenesis through EndoMT.

Converging Pathways: A Review of Pulmonary Hypertension in Interstitial Lung Disease.

Pulmonary hypertension (PH) in interstitial lung disease (ILD) is relatively common, affecting up to 50% of patients with idiopathic pulmonary fibrosis (IPF). It occurs more frequently in advanced fibrotic ILD, although it may also complicate milder disease and carries significant clinical implications in terms of morbidity and mortality. Key pathological processes driving ILD-PH include hypoxic pulmonary vasoconstriction and pulmonary vascular remodelling. While current understanding of the complex cell signalling pathways and molecular mechanisms underlying ILD-PH remains incomplete, there is evidence for an interplay between the disease pathogenesis of fibrotic ILD and PH, with interest in the role of the pulmonary endothelium in driving pulmonary fibrogenesis more recently. This review examines key clinical trials in ILD-PH therapeutics, including recent research showing promise for the treatment of both ILD-PH and the underlying pulmonary fibrotic process, further supporting the hypothesis of interrelated pathogenesis. Other important management considerations are discussed, including the value of accurate phenotyping in ILD-PH and the success of the "pulmonary vascular" phenotype. This article highlights the close and interconnected nature of fibrotic ILD and PH disease pathogenesis, a perspective likely to improve our understanding and therapeutic approach to this complex condition in the future.

Redistribution of SOD3 expression due to R213G polymorphism affects pulmonary interstitial macrophage reprogramming in response to hypoxia.

The extracellular isoform of superoxide dismutase (SOD3) is decreased in patients and animals with pulmonary hypertension (PH). The human R213G single-nucleotide polymorphism (SNP) in SOD3 causes its release from tissue extracellular matrix (ECM) into extracellular fluids, without modulating enzyme activity, increasing cardiovascular disease risk in humans and exacerbating chronic hypoxic PH in mice. Given the importance of interstitial macrophages (IMs) to PH pathogenesis, this study aimed to determine whether R213G SOD3 increases IM accumulation and alters IM reprogramming in response to hypoxia. R213G mice and wild-type (WT) controls were exposed to hypobaric hypoxia for 4 or 14 days compared with normoxia. Flow cytometry demonstrated a transient increase in IMs at day 4 in both strains. Contrary to our hypothesis, the R213G SNP did not augment IM accumulation. To determine strain differences in the IM reprogramming response to hypoxia, we performed RNAsequencing on IMs isolated at each timepoint. We found that IMs from R213G mice exposed to hypoxia activated ECM-related pathways and a combination of alternative macrophage and proinflammatory signaling. Furthermore, when compared with WT responses, IMs from R213G mice lacked metabolic remodeling and demonstrated a blunted anti-inflammatory response between the early (day 4) and later (day 14) timepoints. We confirmed metabolic responses using Agilent Seahorse assays, whereby WT, but not R213G, IMs upregulated glycolysis at day 4 that returned to baseline at day 14. Finally, we identify differential regulation of several redox-sensitive upstream regulators that could be investigated in future studies.NEW & NOTEWORTHY Redistributed expression of SOD3 out of tissue ECM due to the human R213G SNP exacerbates chronic hypoxic PH. Highlighting the importance of macrophage phenotype, our findings reveal that the R213G SNP does not exacerbate pulmonary macrophage accumulation in response to hypoxia but influences their metabolic and phenotypic reprogramming. We demonstrate a deficiency in the metabolic response to hypoxic stress in R213G macrophages, associated with weakened inflammatory resolution and activation of profibrotic pathways implicated in PH.

G6pdN126D Variant Increases the Risk of Developing VEGFR (Vascular Endothelial Growth Factor Receptor) Blocker-Induced Pulmonary Vascular Disease.

G6PD (glucose-6-phosphate-dehydrogenase) is a key enzyme in the glycolytic pathway and has been implicated in the pathogenesis of cancer and pulmonary hypertension-associated vascular remodeling. Here, we investigated the role of an X-linked G6pd mutation (N126D polymorphism), which is known to increase the risk of cardiovascular disease in individuals from sub-Saharan Africa and many others with African ancestry, in the pathogenesis of pulmonary hypertension induced by a vascular endothelial cell growth factor receptor blocker used for treating cancer. CRISPR-Cas9 genome editing was used to generate the G6pd variant (N126D; G6pdN126D) in rats. A single dose of the vascular endothelial cell growth factor receptor blocker sugen-5416 (SU; 20 mg/kg in DMSO), which is currently in a Phase 2/3 clinical trial for cancer treatment, was subcutaneously injected into G6pdN126D rats and their wild-type littermates. After 8 weeks of normoxic conditions, right ventricular pressure and hypertrophy, pulmonary artery remodeling, the metabolic profile, and cytokine expression were assessed. Right ventricular pressure and pulmonary arterial wall thickness were increased in G6PDN126D+SU/normoxic rats. Simultaneously, levels of oxidized glutathione, inositol triphosphate, and intracellular Ca2+ were increased in the lungs of G6PDN126D+SU/normoxic rats, whereas nitric oxide was decreased. Also increased in G6PDN126D+SU/normoxic rats were pulmonary levels of plasminogen activator inhibitor-1, thrombin-antithrombin complex, and expression of proinflammatory cytokines CCL3 (chemokine [C-C motif] ligand), CCL5, and CCL7. Our results suggest G6PDN126D increases inositol triphosphate-Ca2+ signaling, inflammation, thrombosis, and hypertrophic pulmonary artery remodeling in SU-treated rats. This suggests an increased risk of vascular endothelial cell growth factor receptor blocker-induced pulmonary hypertension in those carrying this G6PD variant.

Identification of SNHG11 as a Therapeutic Target in Pulmonary Hypertension.

Pulmonary hypertension (PH) is a life-threatening condition characterized by pulmonary vascular remodeling and endothelial dysfunction. Current therapies primarily target vasoactive imbalances but often fail to address adverse vascular remodeling. Long non-coding RNA (lncRNA), which are key regulators of various cellular processes, remain underexplored in the context of PH. To investigate the role of lncRNA in PH, we performed a comprehensive analysis using Weighted Gene Co-expression Network Analysis (WGCNA) on the GSE113439 dataset, comprising human lung tissue samples from different PH subtypes. Our analysis identified the lncRNA SNHG11 as consistently downregulated in PH. Functional assays in human pulmonary artery endothelial cells (HPAECs) demonstrated that SNHG11 plays a critical role in modulating inflammation, cell proliferation, apoptosis, and the JAK/STAT and MAPK signaling pathways. Mechanistically, SNHG11 influences the stability of PRPF8, a crucial mRNA spliceosome component, thereby affecting multiple cellular functions beyond splicing. In vivo experiments using a hypoxic rat model showed that knockdown of SNHG11 alleviates PH development and improves right ventricular function. These findings highlight SNHG11 as a key regulator in PH pathogenesis and suggest it as a potential therapeutic target.

Circulating free heme induces cytokine storm and pulmonary hypertension through the MKK3/p38 axis.

Hemolysis is associated with pulmonary hypertension (PH), but the direct contribution of circulating free heme to the PH pathogenesis remains unclear. Here, we show that the elevated levels of circulating free heme are sufficient to induce PH and inflammatory response in mice and confirm the critical role of mitogen-activated protein kinase kinase-3 (MKK3)-mediated pathway in free heme signaling. Following the continuous infusion of heme for 2 wk, wild-type (WT) but not MKK3 knockout (KO) mice develop PH, as evidenced by a significantly elevated right ventricular (RV) systolic pressure, RV hypertrophy, and pulmonary vascular remodeling. The MKK3/p38 axis, markedly activated by heme infusion in WTs, results in upregulated proliferative/cytokine signaling targets Akt, ERK1/2, and STAT3, which were abrogated in MKK3 KO mice. Moreover, the MKK3 KOs were protected against heme-mediated endothelial barrier dysfunction by restoring the tight junction protein zonula occludens-1 expression and diminishing the inflammatory cell infiltration in the lungs. Plasma cytokine multiplex analysis revealed a severe cytokine storm already 24 h after initiation of heme infusion, with a significant increase of 19 cytokines, including IL-1b, IL-2, IL-6, IL-9, and TNF-a, in WT animals and complete attenuation of cytokine production in MKK3 KO mice. Together, these findings reveal a causative role of circulating free heme in PH through activating inflammatory and proliferative responses. The central role of MKK3 in orchestrating the heme-mediated pathogenic response supports MKK3 as an attractive therapeutic target for PH and other lung inflammatory diseases linked to hemolytic anemia.NEW & NOTEWORTHY This study demonstrates that elevated levels of circulating free heme can induce pulmonary hypertension (PH) and inflammation in mice. Continuous heme infusion activated the MKK3/p38 pathway, leading to increased right ventricular pressure, right ventricular hypertrophy, and vascular remodeling. This activation upregulated signaling cascades such as Akt, ERK1/2, and STAT3, whereas MKK3 knockout mice were protected against these changes and had reduced inflammatory responses, highlighting MKK3's potential as a therapeutic target for PH.

Lung EC-SOD Overexpression Prevents Hypoxia-Induced Platelet Activation and Lung Platelet Accumulation.

Pulmonary hypertension (PH) is a progressive disease marked by pulmonary vascular remodeling and right ventricular failure. Inflammation and oxidative stress are critical in PH pathogenesis, with early pulmonary vascular inflammation preceding vascular remodeling. Extracellular superoxide dismutase (EC-SOD), a key vascular antioxidant enzyme, mitigates oxidative stress and protects against inflammation and fibrosis in diverse lung and vascular disease models. This study utilizes a murine hypobaric hypoxia model to investigate the role of lung EC-SOD on hypoxia-induced platelet activation and platelet lung accumulation, a critical factor in PH-related inflammation. We found that lung EC-SOD overexpression blocked hypoxia-induced platelet activation and platelet accumulation in the lung. Though lung EC-SOD overexpression increased lung EC-SOD content, it did not impact plasma extracellular SOD activity. However, ex vivo, exogenous extracellular SOD treatment specifically blunted convulxin-induced platelet activation but did not blunt platelet activation with thrombin or ADP. Our data identify platelets as a novel target of EC-SOD in response to hypoxia, providing a foundation to advance the understanding of dysregulated redox signaling and platelet activation in PH and other chronic hypoxic lung diseases.