Immune and inflammatory cell involvement in the pathology of idiopathic pulmonary arterial hypertension

Plasma IL4 Levels Linked to Pulmonary Hypertension Severity and Outcome

BACKGROUND

The anti-inflammatory cytokine interleukin-4 (IL4) has been recognised as a protective factor in various cardiovascular events, yet its prognostic value in patients with pulmonary hypertension (PH) remains unclear. The study aimed to measure the levels of plasma IL4 in patients with PH and to explore their potential association with disease risk and outcomes.

METHODS

In this observational study, we analysed the levels of plasma IL4 in 766 PH patients and 191 healthy controls in Shanghai Pulmonary Hospital from October 2009 to January 2024. To establish the correlations between plasma IL4 levels and the risk and outcomes of PH, all patients were followed up from June 2013 to June 2024. The Spearman correlation test was employed to evaluate the relationships between IL4 and right heart catheterisation parameters among patients with PH. Receiver operating characteristic (ROC) curves were generated to evaluate the diagnostic performance of IL4 for PH. The Cox proportional hazards models and Kaplan-Meier survival curves were used to assess the prognostic value of IL4 levels. Logistic regression analysis was performed to predict PH incidence. A nomogram was constructed to predict mortality, and its clinical utility was validated using decision curve analysis (DCA).

RESULTS

Plasma IL4 levels were significantly decreased in patients with PH compared with controls (p < 0.001), as well as in different PH groups (p < 0.05 for all). The logistic regression analyses indicated that the lower IL4 levels were associated with the high risk of PH (OR = 0.79, 95% CI: 0.716-0.872; p < 0.001). IL4 levels correlated inversely with NT-proBNP (r = -0.10, p < 0.05) and mPAP (r = -0.01, p < 0.05), and positively with CI (r = 0.12, p < 0.05) and PaSaO2 (r = 0.11, p < 0.05), indicating an association with disease severity. Kaplan-Meier analysis revealed that patients with IL4 ≥ 2.8774 pg/mL had a 3-year cumulative survival rate of 91.28%, compared with 82.83% for those with IL4 < 2.8774 pg/mL (log-rank p = 0.007). Cox regression confirmed IL4 as an independent predictor of survival (HR = 0.810, 95% CI: 0.660-0.993; p = 0.043). A diagnostic model combining IL4, 6MWD and NT-proBNP demonstrated good prognostic value (AUC = 0.692, p < 0.0001).

CONCLUSIONS

Plasma IL4 levels were significantly decreased in patients with PH, exhibiting a negative correlation with disease severity; furthermore, lower IL4 levels may serve as a prognostic indicator of poor outcomes in patients with PH.

Rare immune-related adverse effect of pembrolizumab: pulmonary hypertension

Pembrolizumab is an immune checkpoint inhibitor that acts via PD-1 blockade. Recent studies have shown its effectiveness in treating various solid organ tumours. However, unlike cytotoxic chemotherapeutic agents, pembrolizumab may cause immune-related adverse effects. These immune-related adverse effects are generally mild, although patients who experience grade-three or higher side effects may require hospitalisation. In particular, cardiopulmonary side effects are associated with high mortality rates. We report the case of a 24-year-old female patient with alveolar soft part sarcoma accompanied by rare and difficult-to-treat pulmonary hypertension induced by pembrolizumab.

Tet Methylcytosine Dioxygenase 2 (TET2) Mutation Drives a Global Hypermethylation Signature in Patients With Pulmonary Arterial Hypertension (PAH): Correlation With Altered Gene Expression Relevant to a Common T Cell Phenotype

Epigenetic changes in gene expression due to DNA methylation regulate pulmonary vascular structure and function. Genetic or acquired alterations in DNA methylation/demethylation can promote the development of pulmonary arterial hypertension (PAH). Here, we performed epigenome-wide mapping of DNA methylation in whole blood from 10 healthy people and 19 age/sex-matched PAH patients from the PAH Biobank. Exome sequencing confirmed the absence of known mutations in PAH-associated gene variants identifying subjects with or without mutations of TET2, a putative PAH gene encoding the demethylating enzyme, TET2. DNA of patients with PAH and no TET2 mutation was hypermethylated compared to healthy controls. Patients with PAH and a TET2 mutation had greater DNA CpG methylation than mutation-free PAH patients. Unique Differentially Methylated Regions (DMR) were more common in patients with PAH with TET2 mutations (1164) than in PAH without mutations (262). We correlated methylome findings with a public PAH transcriptomic RNA dataset, prioritizing targets that are both hypermethylated in our cohort and downregulated at the RNA level. Relative to controls, functional analysis reveals enriched functions related to T cell differentiation in PAH patients with a TET2 mutation. We identified genes with downregulated expression that were hypermethylated in PAH patients (with or without a TET2 mutation). In both cases, a conserved T cell phenotype emerged. Pan-chromosomal hypermethylation in PAH is greatest in patients with TET2 mutations. Observed hypermethylation of genes involved in the pathogenesis of PAH, such as EIF2AK4, and transcription factors that regulate T cell development, such as TCF7, merit further study and may contribute to the inflammation in PAH.

Correlation between T-lymphocyte subsets and hemodynamics in patients with congenital heart disease-associated pulmonary arterial hypertension

This study aims to explore the correlation between T-lymphocyte subsets and hemodynamics in patients with congenital heart disease-associated pulmonary arterial hypertension (CHD-PAH). Thirty patients with CHD-PAH from Cardiovascular Hospital Affiliated to Shanxi Medical University were included and divided into cardiac function class I to II (low-risk group) and cardiac function class III to IV (high-risk group) according to the World Health Organization functional class. T-lymphocyte subsets levels and hemodynamic parameters related to right heart function were compared between the 2 groups, and correlation analysis of T-lymphocyte subsets levels and hemodynamic parameters related to right heart function was also performed. Color Doppler ultrasonography was used to measure the hemodynamic parameters of the patients, and flow cytometer was used for the detection of T-lymphocyte subsets. The percentage of regulatory T-cells in the high-risk group (3.62 ± 0.72) was lower than that in the low-risk group (4.10 ± 0.48) (P = .039). Compared with the low-risk group, the Th17/Treg and Th2/Treg levels in the high-risk group were significantly increased, and the difference was statistically significant (P < .05). Right ventricular anteroposterior is negatively correlated with regulatory T cell percentage count with a correlation coefficient of -0.373 (P = .042), and positively correlated with Th2/Treg with a correlation coefficient of 0.392 (P = .032). Tricuspid annular plane systolic excursion and tricuspid annular velocity of motion are positively correlated with the percentage count of T-lymphocytes, with correlation coefficients of 0.397 (P = .03) and 0.413 (P = .023), respectively. Pulmonary artery systolic pressure demonstrated a significant positive association with absolute count of T-lymphocytes (R = 0.387, P = .034), helper T cells (R = 0.426, P = .019), suppressor T cells (R = 0.466, P = .009), Th2 cells (R = 0.453, P = .012), Th17 (IL-17) cells (R = 0.408, P = .025). Tricuspid regurgitation velocity is positively correlated with absolute counts of Ts cells (R = 0.426, P = .019) and Th2 (R = 0.361, P = .05) cells. The inferior vena cava collapsibility index is positively correlated with the absolute count of Th1 cells (R = 0.388, P = .034). Our study confirmed that changes in T-lymphocyte subsets were associated with hemodynamic changes in patients, suggesting that T-lymphocyte subsets may be involved in the development of CHD-PAH, and that immunomodulatory therapy may become a new direction for the treatment of CHD-PAH in the future.

Ruxolitinib treatment ameliorates clinical, immunologic, and transcriptomic aberrations in patients with STAT3 gain-of-function disease

BACKGROUND

Signal transducer and activator of transcription 3 (STAT3) gain-of-function (GOF) disease presents with lymphoproliferation, autoimmunity, and failure to thrive. Although Janus kinase inhibitors have alleviated symptoms, their effects on disease pathogenesis remain unclear.

OBJECTIVE

We prospectively investigated the clinical, immunologic, and transcriptomic responses of 4 patients with STAT3 GOF under long-term ruxolitinib treatment.

METHODS

We conducted clinical and immunologic evaluations at baseline and after ruxolitinib treatment at 3, 8, 12, and more than 12 months. Our assessments included measurement of levels of circulating T follicular helper cells, regulatory T cells, and cytokines, as well as proliferation assays. Furthermore, we investigated the transcriptomic changes with treatment and conducted T-cell receptor sequencing.

RESULTS

Ruxolitinib achieved substantial control over the clinical manifestations. Posttreatment evaluations demonstrated a notable increase in naive CD4+ and CD8+ T-cell populations, alongside a significant reduction in effector memory T-cell levels. Additionally, there was a decrease in levels of circulating T follicular helper cells and double-negative T cells. Regulatory T-cell percentages and their canonical markers, which were already reduced before treatment, declined further with ruxolitinib. The treatment did not alter the production of IL-4, IL-17A, IL-10, and IFN-γ cytokines by the CD4+ T cells. Importantly, ruxolitinib effectively normalized the previously dysregulated transcriptome profile in PBMCs, bringing it closer to that of healthy controls. This normalization was most striking in the downregulation of STAT3-targeted genes, interferon-related genes, myeloid cell activation, and cytotoxic effector CD8+ T-cell genes, with effects persisting for up to 12 months. Self-reactive T-cell indices based on T-cell receptor repertoire analysis revealed potential autoreactive cell clones in the patient samples.

CONCLUSION

Ruxolitinib reversed cellular and transcriptomic signatures, enhancing our understanding of the disease's pathophysiology and highlighting essential immunologic markers for precise monitoring.

Associations of Serum Legumain with Severity and Prognosis Among Acute Exacerbation of Chronic Obstructive Pulmonary Disease Patients

Background

A number of studies have demonstrated that legumain is engaged in the pulmonary diseases. Nevertheless, the role of legumain is indistinct in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). The aim is to identify the correlation of serum legumain with AECOPD patients through a prospective cohort study.

Methods

All 202 patients with AECOPD were enrolled. Fasting venous blood was collected. Serum legumain was detected by ELISA.

Results

On admission, serum legumain concentration was gradually elevated in line with AECOPD severity scores. Additionally, serum legumain was closely associated with clinical characteristics. Linear regression analysis confirmed the positive relationships of serum legumain with COPD severity scores. Moreover, the poor prognoses were tracked in patients of AECOPD. Serum higher legumain at admission increased the risks of death and acute exacerbation during hospitalization.

Conclusion

Serum legumain at admission was positively correlated with the severity and adverse prognosis in AECOPD patients, indicating that legumain plays a vital role in the initiation and development of AECOPD. As a result, serum legumain can become a biomarker in the disease assessment and prognosis prediction for AECOPD.

Mechanisms and treatment of pulmonary arterial hypertension

Substantial progress has been made in the management of pulmonary arterial hypertension (PAH) in the past 25 years, but the disease remains life-limiting. Established therapies for PAH are mostly limited to symptomatic relief by correcting the imbalance of vasoactive factors. The tyrosine kinase inhibitor imatinib, the first predominantly non-vasodilatory drug to be tested in patients with PAH, improved exercise capacity and pulmonary haemodynamics compared with placebo but at the expense of adverse events such as subdural haematoma. Given that administration by inhalation might reduce the risk of systemic adverse effects, inhaled formulations of tyrosine kinase inhibitors are currently in clinical development. Other novel therapeutic approaches for PAH include suppression of activin receptor type IIA signalling with sotatercept, which has shown substantial efficacy in clinical trials and was approved for use in the USA in 2024, but the long-term safety of the drug remains unclear. Future advances in the management of PAH will focus on right ventricular function and involve deep phenotyping and the development of a personalized medicine approach. In this Review, we summarize the mechanisms underlying PAH, provide an overview of available PAH therapies and their limitations, describe the development of newer, predominantly non-vasodilatory drugs that are currently being tested in phase II or III clinical trials, and discuss future directions for PAH research.

Monocytes and interstitial macrophages contribute to hypoxic pulmonary hypertension

Hypoxia is a major cause of pulmonary hypertension (PH) worldwide, and it is likely that interstitial pulmonary macrophages contribute to this vascular pathology. We observed in hypoxia-exposed mice an increase in resident interstitial macrophages, which expanded through proliferation and expressed the monocyte recruitment ligand CCL2. We also observed an increase in CCR2+ macrophages through recruitment, which express the protein thrombospondin-1, which functionally activates TGF-β to cause vascular disease. Blockade of monocyte recruitment with either CCL2-neutralizing antibody treatment or CCR2 deficiency in the bone marrow compartment suppressed hypoxic PH. These data were supported by analysis of plasma samples from humans who traveled from low (225 m) to high (3500 m) elevation, revealing an increase in thrombospondin-1 and TGF-β expression following ascent, which was blocked by dexamethasone prophylaxis. In the hypoxic mouse model, dexamethasone prophylaxis recapitulated these findings by mechanistically suppressing CCL2 expression and CCR2+ monocyte recruitment. These data suggest a pathologic cross talk between 2 discrete interstitial macrophage populations, which can be therapeutically targeted.

Impact of sodium-glucose cotransporter-2 inhibitors on pulmonary vascular cell function and arterial remodeling

Sodium-glucose cotransporter-2 (SGLT-2) inhibitors represent a cutting-edge class of oral antidiabetic therapeutics that operate through selective inhibition of glucose reabsorption in proximal renal tubules, consequently augmenting urinary glucose excretion and attenuating blood glucose levels. Extensive clinical investigations have demonstrated their profound cardiovascular efficacy. Parallel basic science research has elucidated the mechanistic pathways through which diverse SGLT-2 inhibitors beneficially modulate pulmonary vascular cells and arterial remodeling. Specifically, these inhibitors exhibit promising potential in enhancing pulmonary vascular endothelial cell function, suppressing pulmonary smooth muscle cell proliferation and migration, reversing pulmonary arterial remodeling, and maintaining hemodynamic equilibrium. This comprehensive review synthesizes current literature to delineate the mechanisms by which SGLT-2 inhibitors enhance pulmonary vascular cell function and reverse pulmonary remodeling, thereby offering novel therapeutic perspectives for pulmonary vascular diseases.

Inflammatory and cardiac biomarkers in pulmonary arterial hypertension: The prognostic role of IL-34

BACKGROUND

Pulmonary arterial hypertension (PAH) is characterized by increased pulmonary artery pressure with significant morbidity and mortality. Inflammatory processes are crucial in PAH pathogenesis, with inflammatory cells and mediators present early in disease progression. IL-34 involvement in inflammatory pathways suggests that IL-34 could be an important player in the progression of PAH, influencing both pulmonary pressures and vascular changes.

OBJECTIVE

The purpose of this study was to investigate the correlation between IL-34 levels and pulmonary arterial hypertension (PAH), aiming to enhance the understanding of the molecular mechanisms underlying PAH and explore IL-34's potential as a biomarker.

METHODS

Consecutive PAH patients diagnosed via right-heart catheterization at Malatya Turgut Ozal Eğitim ve Araştırma Hastanesi (Dec 2022 - Apr 2024) were enrolled. Patients were classified into low-risk and high-risk groups based on comprehensive risk assessments that included clinical parameters, hemodynamic measurements and biomarkers, in-line with ESC/ERS guidelines. Serum IL-34, hs-CRP, and NT-proBNP levels were measured and compared with those of healthy controls. Echocardiographic assessments and statistical analyses, including ROC analysis, were conducted to evaluate biomarker significance and predictive capabilities.

RESULTS

The mean age of low-risk and high-risk PAH patients was 42 ± 7.2 years and 45 ± 5.5 years, respectively. The mean age of the control group was 40 ± 6.4 years. Males comprised 54.29 % of the low-risk group, 56 % of the high-risk group, and 53.3 % of the control group. IL-34 and hs-CRP levels were significantly elevated in PAH patients compared to controls. IL-34 correlated positively with systolic pulmonary artery pressure, RA area, and NT-proBNP levels. Multivariate analysis revealed that IL-34 and hs-CRP were independent predictors of PAH. IL-34 levels>29.8 pg/mL predicted PAH with 78 % sensitivity and 69 % specificity, while levels >44.4 pg/mL predicted high-risk PAH with 84 % sensitivity and 77 % specificity.

CONCLUSION

Elevated IL-34 and hs-CRP levels are associated with PAH severity and right ventricular dysfunction, suggesting IL-34's potential as a diagnostic and prognostic biomarker. Further research is needed to validate these findings and explore IL-34-targeted therapies in pH management.

Identification of potential diagnostic biomarkers and therapeutic targets in patients with hypoxia pulmonary hypertension

BACKGROUND

Pulmonary hypertension is a serious disease. Emerging studies have shown that M2 macrophages play an essential role in pulmonary hypertension; however, their mechanism of action is uncertain.

METHODS

Four GEO datasets were downloaded. The differentially expressed genes (DEGs) were obtained using the limma package. Simultaneously, the Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts (CIBERSORT) algorithm and weighted gene co-expression network analysis (WGCNA) were used to get the information about M2 macrophage-related modules. Potential key genes were obtained by intersecting DEGs with M2 macrophage-related module genes (M2MRGs), and finally the area under the curve (AUC) was calculated. Rats were exposed to hypoxia condition (10 % O2) for 4 weeks to induce PH. Subsequently, potential key genes with AUC>0.7 were analyzed by quantitative real-time polymerase chain reaction and Western blot using normoxia and hypoxia rat lungs. We knocked down EPHA3 in Raw264.7 cells and detected the protein expression of M2 macrophage markers including arginase 1 (ARG1) and interleukin 10 (IL-10), phospho-protein kinase B (P-Akt), and protein kinase B (Akt) to explore the downstream pathways of EPHA3.

RESULTS

Seven potential hub genes were detected by intersecting M2MRGs and DEGs. Six genes with AUC values above 0.7 were used for further exploration. The expression of EPHA3 mRNA and protein was significantly more upregulated in rats with hypoxia than in rats with normoxia. The expression levels of IL10, ARG1, and P-Akt/Akt decreased after knocking down EPHA3.

CONCLUSIONS

This study suggested that the activation of the P-Akt/Akt signaling pathway promoted by EPHA3 played an essential role in the progression of pulmonary hypertension.

Cathepsin L Promotes Pulmonary Hypertension via BMPR2/GSDME-Mediated Pyroptosis

BACKGROUND

Pulmonary hypertension (PH) is a fatal progressive disease characterized by pulmonary endothelial injury and occlusive pulmonary vascular remodeling. Lysosomal protease cathepsin L degrades essential molecules to participate in the human pathophysiological process. BMPR2 (bone morphogenetic protein type II receptor) deficiency, an important cause of PH, results from mutational inactivation or excessive lysosomal degradation and induces caspase-3-mediated cell death. Given recent evidence that pyroptosis, as a new form of programmed cell death, is induced by caspase-3-dependent GSDME (gasdermin E) cleavage, we hypothesized that cathepsin L might promote PH through BMPR2/caspase-3/GSDME axis-mediated pyroptosis.

METHODS

Cathepsin L expression was evaluated in the lungs and plasma of patients with pulmonary arterial hypertension. The role of cathepsin L in the progression of PH and vascular remodeling was assessed in vivo. Small interfering RNA, specific inhibitors, and lentiviruses were used to explore the mechanisms of cathepsin L on human pulmonary arterial endothelial cell dysfunction.

RESULTS

Cathepsin L expression is elevated in pulmonary artery endothelium from patients with idiopathic pulmonary arterial hypertension and experimental PH models. Genetic ablation of cathepsin L in PH rats relieved right ventricular systolic pressure, pulmonary vascular remodeling, and right ventricular hypertrophy, also restoring endothelial integrity. Mechanistically, cathepsin L promotes caspase-3/GSDME-mediated endothelial cell pyroptosis and represses BMPR2 signaling activity. Cathepsin L degrades BMPR2 via the lysosomal pathway, and restoring BMPR2 signaling prevents the pro-pyroptotic role of cathepsin L in PAECs and experimental PH models.

CONCLUSIONS

These results show for the first time that cathepsin L promotes the development of PH by degrading BMPR2 to induce caspase-3/GSDME-mediated endothelial pyroptosis.

Immunoregulatory Macrophages Modify Local Pulmonary Immunity and Ameliorate Hypoxic Pulmonary Hypertension

BACKGROUND

Macrophages play a significant role in the onset and progression of vascular disease in pulmonary hypertension, and cell-based immunotherapies aimed at treating vascular remodeling are lacking. We aimed to evaluate the effect of pulmonary administration of macrophages modified to have an anti-inflammatory/proresolving phenotype in attenuating early pulmonary inflammation and progression of experimentally induced pulmonary hypertension.

METHODS

Mouse bone marrow-derived macrophages were polarized in vitro to a regulatory (M2reg) phenotype. M2reg profile and anti-inflammatory capacity were assessed in vitro upon lipopolysaccharide/IFNγ (interferon-γ) restimulation, before their administration to 8- to 12-week-old mice. M2reg protective effect was evaluated at early (2-4 days) and late (4 weeks) time points during hypoxia (8.5% O2) exposure. Levels of inflammatory markers were quantified in alveolar macrophages and whole lung, while pulmonary hypertension development was ascertained by right ventricular systolic pressure (RVSP) and right ventricular hypertrophy measurements. Bronchoalveolar lavage from M2reg-transplanted hypoxic mice was collected and its inflammatory potential evaluated on naive bone marrow-derived macrophages.

RESULTS

M2reg macrophages expressing Tgfβ, Il10, and Cd206 demonstrated a stable anti-inflammatory phenotype in vitro, by downregulating the induction of proinflammatory cytokines and surface molecules (Cd86, Il6, and Tnfα) upon a subsequent proinflammatory stimulus. A single dose of M2regs attenuated hypoxic monocytic recruitment and perivascular inflammation. Early hypoxic lung and alveolar macrophage inflammation leading to pulmonary hypertension development was significantly reduced, and, importantly, M2regs attenuated right ventricular hypertrophy, right ventricular systolic pressure, and vascular remodeling at 4 weeks post-treatment.

CONCLUSIONS

Adoptive transfer of M2regs halts the recruitment of monocytes and modifies the hypoxic lung microenvironment, potentially changing the immunoreactivity of recruited macrophages and restoring normal immune functionality of the lung. These findings provide new mechanistic insights into the diverse role of macrophage phenotype on lung vascular homeostasis that can be explored as novel therapeutic targets.

Intestinal IFNα4 promotes 15-HETE diet-induced pulmonary hypertension

OBJECTIVES

Pulmonary arterial hypertension (PAH) is characterized by the remodeling of the pulmonary vascular bed leading to elevation of the pulmonary arterial pressure. Oxidized fatty acids, such as hydroxyeicosatetraenoic acids (HETEs), play a critical role in PAH. We have previously established that dietary supplementation of 15-HETE is sufficient to cause PH in mice, suggesting a role for the gut-lung axis. However, the mechanisms are not known.

APPROACH

Analysis of RNA-seq data obtained from the lungs and intestines of mice on 15-HETE diet together with transcriptomic data from PAH patient lungs identified IFN inducible protein 44 (IFI44) as the only gene significantly upregulated in mice and humans. We demonstrate that IFI44 is also significantly increased in PBMCs from PAH patients. In mice, 15-HETE diet enhances IFI44 and its inducer IFN⍺4 expression sequentially in the intestine first and then in the lungs. IFI44 expression in PAH is highly correlated with expression of Tumor Necrosis Factor Related Apoptosis Inducing Ligand (TRAIL), which is upregulated in CD8 cells in PH lungs of both mice and humans. We show that IFNα4 produced by intestinal epithelial cells facilitates IFI44 expression in CD8 cells. Finally, we demonstrate that IFN receptor 1-KO in mice do not develop PH on 15-HETE diet. In addition, silencing IFI44 expression in the lungs of mice on 15-HETE diet prevents the development of PH and is associated with significantly lower expression of IFI44 and TRAIL in CD8 cells in the lungs.

CONCLUSION

Our data reveal a novel gut-lung axis driven by 15-HETE in PH.

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.

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.

Pulmonary Artery Denervation: An Emerging Treatment for Pulmonary Hypertension

Pulmonary hypertension (PH) is a debilitating disease with a poor overall prognosis. Pulmonary artery denervation (PADN) has emerged as a promising new treatment which has been shown to improve hemodynamics, functionality, and REVEAL scores for patients with PH. This article reviews notable updates in the management of PH since the 6th World Symposium on PH, the pathophysiology of PH, how PADN may work given the pathophysiology of PH, and focuses on evidence from the eleven studies supporting the use of PADN from trials that include human participants.

Current Overview of the Biology and Pharmacology in Sugen/Hypoxia-Induced Pulmonary Hypertension in Rats

The Sugen 5416/hypoxia (Su/Hx) rat model of pulmonary arterial hypertension (PAH) demonstrates most of the distinguishing features of PAH in humans, including increased wall thickness and obstruction of the small pulmonary arteries along with plexiform lesion formation. Recently, significant advancement has been made describing the epidemiology, genomics, biochemistry, physiology, and pharmacology in Su/Hx challenge in rats. For example, there are differences in the overall reactivity to Su/Hx challenge in different rat strains and only female rats respond to estrogen treatments. These conditions are also encountered in human subjects with PAH. Also, there is a good translation in both the biochemical and metabolic pathways in the pulmonary vasculature and right heart between Su/Hx rats and humans, particularly during the transition from the adaptive to the nonadaptive phase of right heart failure. Noninvasive techniques such as echocardiography and magnetic resonance imaging have recently been used to evaluate the progression of the pulmonary vascular and cardiac hemodynamics, which are important parameters to monitor the efficacy of drug treatment over time. From a pharmacological perspective, most of the compounds approved clinically for the treatment of PAH are efficacious in Su/Hx rats. Several compounds that show efficacy in Su/Hx rats have advanced into phase II/phase III studies in humans with positive results. Results from these drug trials, if successful, will provide additional treatment options for patients with PAH and will also further validate the excellent translation that currently exists between Su/Hx rats and the human PAH condition.

Infection and pulmonary vascular diseases consortium: United against a global health challenge

Leveraging the potential of virtual platforms in the post-COVID-19 era, the Infection and Pulmonary Vascular Diseases Consortium (iPVDc), with the support of the Pulmonary Vascular Research Institute (PVRI), launched a globally accessible educational program to highlight top-notch research on inflammation and infectious diseases affecting the lung vasculature. This innovative virtual series has already successfully brought together distinguished investigators across five continents - Asia, Europe, South and North America, and Africa. Moreover, these open global forums have contributed to a comprehensive understanding of the complex interplay among immunology, inflammation, infection, and cardiopulmonary health, especially concerning pulmonary hypertension and related pulmonary disorders. These enlightening discussions have not only heightened awareness about the impact of various pathogenic microorganisms, including fungi, parasites, and viruses, on the onset and development of pulmonary vascular diseases but have also cast a spotlight on co-infections and neglected illnesses like schistosomiasis - a disease that continues to impose a heavy socioeconomic burden in numerous regions worldwide. Thus, the overall goal of this review article is to present the most recent breakthroughs from infectious PVDs as well as bring to light the scientific and educational insights from the 2023 iPVDc/PVRI virtual symposium series, shaping our understanding of these crucial health issues in this more than ever interconnected world.

The hepcidin-ferroportin axis influences mitochondrial function, proliferation, and migration in pulmonary artery endothelial and smooth muscle cells

Elevated circulating hepcidin levels have been reported in patients with pulmonary artery hypertension (PAH). Hepcidin has been shown to promote proliferation of human pulmonary artery smooth muscle cells (PASMCs) in vitro, suggesting a potential role in PAH pathogenesis. However, the role of human pulmonary artery endothelial cells (PAECs) as either a source of hepcidin, or the effect of hepcidin on PAEC function is not as well described. The objective of this study was to define the role of the hepcidin-ferroportin axis on the phenotype of PAEC and to study potential PAEC-PASMC interactions relevant to the pathogenesis of pulmonary vascular remodeling and PAH. PAECs treated with hepcidin, or interleukin-6 were investigated for both ferroportin and hepcidin release and regulation using immunofluorescence, mRNA levels and cellular release assays. Effects of hepcidin on PASMC and PAEC mitochondrial function was investigated using immunofluorescence and seahorse assay. Migration and proliferation of PASMCs treated with conditioned media from hPAEC treated with hepcidin was investigated using the xCELLigence system and other tools. We demonstrate in this study that PAECs express ferroportin; hepcidin treatment of PAECs resulted in mitochondrial iron accumulation and intracellular hepcidin biosynthesis and release. Conditioned media from hepcidin treated PAECs caused PASMCs to down-regulate ferroportin expression whilst promoting migration and proliferation. Inhibition of hepcidin in PAEC conditioned media limited these responses. PASMC cellular and mitochondrial iron retention are associated with migratory and proliferative responses. This study confirms that the hepcidin ferroportin axis is present and operational in PAECs. Modulation of this axis shows distinct differences in responses seen between PAECS and PASMCs. Stimulation of this axis in PAECs with hepcidin may well institute proliferative and migratory responses in PASMCs of relevance to pathogenesis of PAH offering potential novel therapeutic targets.

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.

Crosstalk between cytokines, inflammation and pulmonary arterial hypertension in heart transplant patients

BACKGROUND

Heart transplant (HT) is a therapeutic option for patients with advanced heart failure (HF) refractory to optimized treatment. Patients with advanced HF often develop pulmonary arterial hypertension (PAH). PAH is defined as a condition in which the mean pulmonary artery pressure is greater than 20 mmHg. Inflammation is an important aspect of PAH development. In this context, the objective of this work was to evaluate the relationship between the inflammatory process and the development of HAP in patients undergoing HT.

METHODS

The levels of interleukins IL-6, IL-1β and TNF-α were obtained by ELISA and associated with CD68+ and CD66b neutrophil counts using the immunofluorescence technique in fragments of the pulmonary arteries of donors and patients with or without chagasic cardiomyopathy subjected to HT.

RESULTS

The results showed a positive, statistically significant correlation (p < 0.05) between right atrium pressure levels and IL-6. Furthermore, negative, moderate, and statistically significant correlations (p < 0.05) were observed between the variables cardiac index and TNF-α, and between the levels of transpulmonary pressure grandient and TNF-α. The study also revealed the presence of a statistically significant difference (p < 0.05) between patients who died within 30 days and the highest number of CD68 cells per square micrometer in the vessel of the donor and recipient patient.

CONCLUSION

Suggesting the presence of a pro-inflammatory profile in HT patients, independent of measured pulmonary artery pressure levels.

Classical dendritic cells contribute to hypoxia-induced pulmonary hypertension

Pulmonary hypertension (PH) is a chronic and progressive disease with significant morbidity and mortality. It is characterized by remodeled pulmonary vessels associated with perivascular and intravascular accumulation of inflammatory cells. Although there is compelling evidence that bone marrow-derived cells, such as macrophages and T cells, cluster in the vicinity of pulmonary vascular lesions in humans and contribute to PH development in different animal models, the role of dendritic cells in PH is less clear. Dendritic cells' involvement in PH is likely since they are responsible for coordinating innate and adaptive immune responses. We hypothesized that dendritic cells drive hypoxic PH. We demonstrate that a classical dendritic cell (cDC) subset (cDC2) is increased and activated in wild-type mouse lungs after hypoxia exposure. We observe significant protection after the depletion of cDCs in ZBTB46 DTR chimera mice before hypoxia exposure and after established hypoxic PH. In addition, we find that cDC depletion is associated with a reduced number of two macrophage subsets in the lung (FolR2+ MHCII+ CCR2+ and FolR2+ MHCII+ CCR2-). We found that depleting cDC2s, but not cDC1s, was protective against hypoxic PH. Finally, proof-of-concept studies in human lungs show increased perivascular cDC2s in patients with Idiopathic Pulmonary Arterial Hypertension (IPAH). Our data points to an essential role of cDCs, particularly cDC2s, in the pathophysiology of experimental PH.

A novel PDGFR inhibitor WQ-C-401 prevents pulmonary vascular remodeling in rats with monocrotaline-induced pulmonary arterial hypertension

Platelet-derived growth factor (PDGF) is one of the most important cytokines associated with pulmonary vascular remodeling in pulmonary arterial hypertension (PAH). PDGF receptor (PDGFR) inhibition exerted therapeutic effects on PAH in clinical trials, but serious side effects warrant the withdrawal of existing drugs. In this study, a novel highly selective PDGFR inhibitor WQ-C-401 was developed, and its effects on PDGFR signaling pathway and pulmonary vascular remodeling in PAH were investigated. Cell proliferation assays and Western blot analysis of PDGFRα/β phosphorylation showed that WQ-C-401 inhibited PDGFR-mediated cell proliferation assay and suppressed PDGFR phosphorylation in a concentration-dependent manner. DiscoverX's KinomeScanTM technology confirmed the good kinome selectivity of WQ-C-401 (S score (1) of PDGFR = (0.01)). In monocrotaline (MCT)-induced PAH rats, intragastric administration of WQ-C-401 (25, 50, 100 mg/kg/d) or imatinib (50 mg/kg/d, positive control) significantly decreased right ventricular systolic pressure (RVSP). Histological analysis demonstrated that WQ-C-401 inhibited pulmonary vascular remodeling by reducing muscularization and fibrosis, as well as alleviated right ventricular hypertrophy in MCT-treated rats. In addition, WQ-C-401 suppressed MCT-induced cell hyperproliferation and CD68+ macrophage infiltration around the pulmonary artery. In vitro, WQ-C-401 inhibited PDGF-BB-induced proliferation and migration of human pulmonary arterial smooth muscle cells (PASMCs). Moreover, Western blot analysis showed that WQ-C-401 concertration-dependently inhibited PDGF-BB-induced phosphorylation of ERK1/2 and PDGFRβ Y751, decreased collagen Ⅰ synthesis and increased alpha smooth muscle actin (α-SMA) expression in PASMCs. Collectively, our results suggest that WQ-C-401 is a selective and potent PDGFR inhibitor which could be a promising drug for the therapeutics of PAH by preventing pulmonary vascular remodeling.

Digital Spatial Profiling Identifies Distinct Molecular Signatures of Vascular Lesions in Pulmonary Arterial Hypertension

Rationale: Idiopathic pulmonary arterial hypertension (IPAH) is characterized by extensive pulmonary vascular remodeling caused by plexiform and obliterative lesions, media hypertrophy, inflammatory cell infiltration, and alterations of the adventitia. Objective: We sought to test the hypothesis that microscopic IPAH vascular lesions express unique molecular profiles, which collectively are different from control pulmonary arteries. Methods: We used digital spatial transcriptomics to profile the genomewide differential transcriptomic signature of key pathological lesions (plexiform, obliterative, intima+media hypertrophy, and adventitia) in IPAH lungs (n = 11) and compared these data with the intima+media hypertrophy and adventitia of control pulmonary artery (n = 5). Measurements and Main Results: We detected 8,273 transcripts in the IPAH lesions and control lung pulmonary arteries. Plexiform lesions and IPAH adventitia exhibited the greatest number of differentially expressed genes when compared with intima+media hypertrophy and obliterative lesions. Plexiform lesions in IPAH showed enrichment for 1) genes associated with transforming growth factor β signaling and 2) mutated genes affecting the extracellular matrix and endothelial-mesenchymal transformation. Plexiform lesions and IPAH adventitia showed upregulation of genes involved in immune and IFN signaling, coagulation, and complement pathways. Cellular deconvolution indicated variability in the number of vascular and inflammatory cells between IPAH lesions, which underlies the differential transcript profiling. Conclusions: IPAH lesions express unique molecular transcript profiles enriched for pathways involving pathogenetic pathways, including genetic disease drivers, innate and acquired immunity, hypoxia sensing, and angiogenesis signaling. These data provide a rich molecular-structural framework in IPAH vascular lesions that inform novel biomarkers and therapeutic targets in this highly morbid disease.

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.

Bibliometric analysis of T-cells immunity in pulmonary hypertension from 1992 to 2022

BACKGROUND

Adaptive immunity is an important disease mediator of pulmonary vascular remodeling during pulmonary hypertension (PH) development, especially T-cells lymphocytes. However, data for bibliometric analysis of T cell immunity in PH is currently vacant. This aimed to provide a comprehensive and visualized view of T-cells research in PH pathogenesis and to lay a solid foundation for further studies.

METHODS

The data was acquired from the Web of Science Core Collection database. Web of Science analytic tool was used to analysis the publication years, authors, journals, countries, and organizations. CiteSpace 6.2.R3, VOSviewer 1.6.16, and Scimago Graphica 1.0.35.0 were applied to conduct a visualization bibliometric analysis about authors, countries, institutions, journals, references, and keywords.

RESULTS

Nine hundred and eight publications from 1992 to 2022 were included in the analysis. The results showed that Humbert Marc was the most prolific author. American Journal of Physiology Lung Cellular and Molecular Physiology had the most related articles. The institution with the most articles was Udice French Research University. The United States was far ahead in the article output. Keywords analysis showed that "Pulmonary hypertension" was the most usually appeared keyword in the relevant literature, and included "T-cells", "Regulatory T cells", and "Activated T cell." "miRNA" of reference co-citation clustering analysis demonstrated the possible T-cell immunity activation mechanisms in PH. The most cited literature was published in the European Heart Journal by Galie N in 2016. The strongest citation burst of keyword is "gene expression" and terms such as "vascular remodeling," "growth," "proliferation," and "fibrosis" are among the list, indicating that T-cells interact with stromal vascular cells to induce pulmonary vascular remodeling. The strongest burst of cited reference is "Galie N, 2016."

CONCLUSIONS

T-cell immunity is an important pathogenesis mechanism for PH development, which may have interaction with miRNAs and stromal vascular cells, but the possible T-cell immunity activation mechanisms in PH need to be investigated further.

Ginsenoside Rg1 alleviates vascular remodeling in hypoxia-induced pulmonary hypertension mice through the calpain-1/STAT3 signaling pathway

Background

Hypoxic pulmonary hypertension (HPH) is the main pathological change in vascular remodeling, a complex cardiopulmonary disease caused by hypoxia. Some research results have shown that ginsenoside Rg1 (Rg1) can improve vascular remodeling, but the effect and mechanism of Rg1 on hypoxia-induced pulmonary hypertension are not clear. The purpose of this study was to discuss the potential mechanism of action of Rg1 on HPH.

Methods

C57BL/6 mice, calpain-1 knockout mice and Pulmonary artery smooth muscle cells (PASMCs) were exposed to a low oxygen environment with or without different treatments. The effect of Rg1 and calpain-1 silencing on inflammation, fibrosis, proliferation and the protein expression levels of calpain-1, STAT3 and p-STAT3 were determined at the animal and cellular levels.

Results

At the mouse and cellular levels, hypoxia promotes inflammation, fibrosis, and cell proliferation, and the expression of calpain-1 and p-STAT3 is also increased. Ginsenoside Rg1 administration and calpain-1 knockdown, MDL-28170, and HY-13818 treatment showed protective effects on hypoxia-induced inflammation, fibrosis, and cell proliferation, which may be associated with the downregulation of calpain-1 and p-STAT3 expression in mice and cells. In addition, overexpression of calpain 1 increased p-STAT3 expression, accelerating the onset of inflammation, fibrosis and cell proliferation in hypoxic PASMCs.

Conclusion

Ginsenoside Rg1 may ameliorate hypoxia-induced pulmonary vascular remodeling by suppressing the calpain-1/STAT3 signaling pathway.

The Intersection of HIV and Pulmonary Vascular Health: From HIV Evolution to Vascular Cell Types to Disease Mechanisms

People living with HIV (PLWH) face a growing burden of chronic diseases, owing to the combinations of aging, environmental triggers, lifestyle choices, and virus-induced chronic inflammation. The rising incidence of pulmonary vascular diseases represents a major concern for PLWH. The study of HIV-associated pulmonary vascular complications ideally requires a strong understanding of pulmonary vascular cell biology and HIV pathogenesis at the molecular level for effective applications in infectious diseases and vascular medicine. Active HIV infection and/or HIV proteins disturb the delicate balance between vascular tone and constriction, which is pivotal for maintaining pulmonary vascular health. One of the defining features of HIV is its high genetic diversity owing to several factors including its high mutation rate, recombination between viral strains, immune selective pressures, or even geographical factors. The intrinsic HIV genetic diversity has several important implications for pathogenic outcomes of infection and the overall battle to combat HIV. Challenges in the field present themselves from two sides of the same coin: those imposed by the virus itself and those stemming from the host. The field may be advanced by further developing in vivo and in vitro models that are well described for both pulmonary vascular diseases and HIV for mechanistic studies. In essence, the study of HIV-associated pulmonary vascular complications requires a multidisciplinary approach, drawing upon insights from both infectious diseases and vascular medicine. In this review article, we discuss the fundamentals of HIV virology and their impact on pulmonary disease, aiming to enhance the understanding of either area or both simultaneously. Bridging the gap between preclinical research findings and clinical practice is essential for improving patient care. Addressing these knowledge gaps requires interdisciplinary collaborations, innovative research approaches, and dedicated efforts to prioritize HIV-related pulmonary complications on the global research agenda.

A new integrative analysis of histopathology and single cell RNA-seq reveals the CCL5 mediated T and NK cell interaction with vascular cells in idiopathic pulmonary arterial hypertension

BACKGROUND

Inflammation and dysregulated immunity play vital roles in idiopathic pulmonary arterial hypertension (IPAH), while the mechanisms that initiate and promote these processes are unclear.

METHODS

Transcriptomic data of lung tissues from IPAH patients and controls were obtained from the Gene Expression Omnibus database. Weighted gene co-expression network analysis (WGCNA), differential expression analysis, protein-protein interaction (PPI) and functional enrichment analysis were combined with a hemodynamically-related histopathological score to identify inflammation-associated hub genes in IPAH. The monocrotaline-induced rat model of pulmonary hypertension was utilized to confirm the expression pattern of these hub genes. Single-cell RNA-sequencing (scRNA-seq) data were used to identify the hub gene-expressing cell types and their intercellular interactions.

RESULTS

Through an extensive bioinformatics analysis, CXCL9, CCL5, GZMA and GZMK were identified as hub genes that distinguished IPAH patients from controls. Among these genes, pulmonary expression levels of Cxcl9, Ccl5 and Gzma were elevated in monocrotaline-exposed rats. Further investigation revealed that only CCL5 and GZMA were highly expressed in T and NK cells, where CCL5 mediated T and NK cell interaction with endothelial cells, smooth muscle cells, and fibroblasts through multiple receptors.

CONCLUSIONS

Our study identified a new inflammatory pathway in IPAH, where T and NK cells drove heightened inflammation predominantly via the upregulation of CCL5, providing groundwork for the development of targeted therapeutics.

Fibroblasts in Pulmonary Hypertension: Roles and Molecular Mechanisms

Fibroblasts, among the most prevalent and widely distributed cell types in the human body, play a crucial role in defining tissue structure. They do this by depositing and remodeling extracellular matrixes and organizing functional tissue networks, which are essential for tissue homeostasis and various human diseases. Pulmonary hypertension (PH) is a devastating syndrome with high mortality, characterized by remodeling of the pulmonary vasculature and significant cellular and structural changes within the intima, media, and adventitia layers. Most research on PH has focused on alterations in the intima (endothelial cells) and media (smooth muscle cells). However, research over the past decade has provided strong evidence of the critical role played by pulmonary artery adventitial fibroblasts in PH. These fibroblasts exhibit the earliest, most dramatic, and most sustained proliferative, apoptosis-resistant, and inflammatory responses to vascular stress. This review examines the aberrant phenotypes of PH fibroblasts and their role in the pathogenesis of PH, discusses potential molecular signaling pathways underlying these activated phenotypes, and highlights areas of research that merit further study to identify promising targets for the prevention and treatment of PH.

Activation of CaMKII/HDAC4 by SDF1 contributes to pulmonary arterial hypertension via stabilization Runx2

Stromal derived factor 1 (SDF1) has been shown to be involved in the pathogenesis of pulmonary artery hypertension (PAH). However, the detailed molecular mechanisms remain unclear. To address this, we utilized primary cultured rat pulmonary artery smooth muscle cells (PASMCs) and monocrotaline (MCT)-induced PAH rat models to investigate the mechanisms of SDF1 driving PASMCs proliferation and pulmonary arterial remodeling. SDF1 increased runt-related transcription factor 2 (Runx2) acetylation by Calmodulin (CaM)-dependent protein kinase II (CaMKII)-dependent HDAC4 cytoplasmic translocation, elevation of Runx2 acetylation conferred its resistance to proteasome-mediated degradation. The accumulation of Runx2 further upregulated osteopontin (OPN) expression, finally leading to PASMCs proliferation. Blocking SDF1, suppression of CaMKII, inhibition the nuclear export of HDAC4 or silencing Runx2 attenuated pulmonary arterial remodeling and prevented PAH development in MCT-induced PAH rat models. Our study provides novel sights for SDF1 induction of PASMCs proliferation and suggests that targeting SDF1/CaMKII/HDAC4/Runx2 axis has potential value in the management of PAH.

Predominance of M2 macrophages in organized thrombi in chronic thromboembolic pulmonary hypertension patients

Chronic thromboembolic pulmonary hypertension (CTEPH) is a debilitating disease characterized by thrombotic occlusion of pulmonary arteries and vasculopathy, leading to increased pulmonary vascular resistance and progressive right-sided heart failure. Thrombotic lesions in CTEPH contain CD68+ macrophages, and increasing evidence supports their role in disease pathogenesis. Macrophages are classically divided into pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages, which are involved in wound healing and tissue repair. Currently, the phenotype of macrophages and their localization within thrombotic lesions of CTEPH are largely unknown. In our study, we subclassified thrombotic lesions of CTEPH patients into developing fresh thrombi (FT) and organized thrombi (OT), based on the degree of fibrosis and remodeling. We used multiplex immunofluorescence histology to identify immune cell infiltrates in thrombotic lesions of CPTEH patients. Utilizing software-assisted cell detection and quantification, increased proportions of macrophages were observed in immune cell infiltrates of OT lesions, compared with FT. Strikingly, the proportions with a CD206+INOS- M2 phenotype were significantly higher in OT than in FT, which mainly contained unpolarized macrophages. Taken together, we observed a shift from unpolarized macrophages in FT toward an expanded population of M2 macrophages in OT, indicating a dynamic role of macrophages during CTEPH pathogenesis.

Dysfunctional regulatory T cell: May be an obstacle to immunotherapy in cardiovascular diseases

Inflammatory responses are linked to cardiovascular diseases (CVDs) in various forms. Tregs, members of CD4+ T cells, play important roles in regulating immune system and suppressing inflammatory response, thus contributing to maintaining immune homeostasis. However, Tregs exert their powerful suppressive function relying on the stable phenotype and function. The stability of Tregs primarily depends on the FOXP3 (Forkhead box P3) expression and epigenetic regulation. Although Tregs are quite stable under physiological conditions, prolonged exposure to inflammatory cues, Tregs may lose suppressive function and require proinflammatory phenotype, namely plastic Tregs or ex-Tregs. There are extensive researches have established the beneficial role of Tregs in CVDs. Nevertheless, the potential risks of dysfunctional Tregs lack deep research. Anti-inflammatory and immunological modulation have been hotspots in the treatment of CVDs. Tregs are appealing because of their crucial role in resolving inflammation and promoting tissue repair. If alleviating inflammatory response through modulating Tregs could be a new therapeutic strategy for CVDs, the next step to consider is how to prevent the formation of dysfunctional Tregs or reverse detrimental Tregs to normal phenotype.

B-cells in pulmonary arterial hypertension: friend, foe or bystander?

There is an unmet need for new therapeutic strategies that target alternative pathways to improve the prognosis of patients with pulmonary arterial hypertension (PAH). As immunity has been involved in the development and progression of vascular lesions in PAH, we review the potential contribution of B-cells in its pathogenesis and evaluate the relevance of B-cell-targeted therapies. Circulating B-cell homeostasis is altered in PAH patients, with total B-cell lymphopenia, abnormal subset distribution (expansion of naïve and antibody-secreting cells, reduction of memory B-cells) and chronic activation. B-cells are recruited to the lungs through local chemokine secretion, and activated by several mechanisms: 1) interaction with lung vascular autoantigens through cognate B-cell receptors; 2) costimulatory signals provided by T follicular helper cells (interleukin (IL)-21), type 2 T helper cells and mast cells (IL-4, IL-6 and IL-13); and 3) increased survival signals provided by B-cell activating factor pathways. This activity results in the formation of germinal centres within perivascular tertiary lymphoid organs and in the local production of pathogenic autoantibodies that target the pulmonary vasculature and vascular stabilisation factors (including angiotensin-II/endothelin-1 receptors and bone morphogenetic protein receptors). B-cells also mediate their effects through enhanced production of pro-inflammatory cytokines, reduced anti-inflammatory properties by regulatory B-cells, immunoglobulin (Ig)G-induced complement activation, and IgE-induced mast cell activation. Precision-medicine approaches targeting B-cell immunity are a promising direction for select PAH conditions, as suggested by the efficacy of anti-CD20 therapy in experimental models and a trial of rituximab in systemic sclerosis-associated PAH.

Pulmonary arterial hypertension associated with connective tissue diseases (CTD-PAH): Recent and advanced data

Pulmonary arterial hypertension (PAH), corresponding to group 1 of pulmonary hypertension classification, is a rare disease with a major prognostic impact on morbidity and mortality. PAH can be either primary in idiopathic and heritable forms or secondary to other conditions including connective tissue diseases (CTD-PAH). Within CTD-PAH, the leading cause of PAH is systemic sclerosis (SSc) in Western countries, whereas systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD) are predominantly associated with PAH in Asia. Although many advances have been made during the last two decades regarding classification, definition early screening and risk stratification and therapeutic aspects with initial combination treatment, the specificities of CTD-PAH are not yet clear. In this manuscript, we review recent literature data regarding the updated definition and classification of PAH, pathogenesis, epidemiology, detection, prognosis and treatment of CTD-PAH.

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.

Single-Cell Imaging Maps Inflammatory Cell Subsets to Pulmonary Arterial Hypertension Vasculopathy

Rationale: Unraveling immune-driven vascular pathology in pulmonary arterial hypertension (PAH) requires a comprehensive understanding of the immune cell landscape. Although patients with hereditary (H)PAH and bone morphogenetic protein receptor type 2 (BMPR2) mutations have more severe pulmonary vascular pathology, it is not known whether this is related to specific immune cell subsets. Objectives: This study aims to elucidate immune-driven vascular pathology by identifying immune cell subtypes linked to severity of pulmonary arterial lesions in PAH. Methods: We used cutting-edge multiplexed ion beam imaging by time of flight to compare pulmonary arteries (PAs) and adjacent tissue in PAH lungs (idiopathic [I]PAH and HPAH) with unused donor lungs, as controls. Measurements and Main Results: We quantified immune cells' proximity and abundance, focusing on those features linked to vascular pathology, and evaluated their impact on pulmonary arterial smooth muscle cells (SMCs) and endothelial cells. Distinct immune infiltration patterns emerged between PAH subtypes, with intramural involvement independently linked to PA occlusive changes. Notably, we identified monocyte-derived dendritic cells within PA subendothelial and adventitial regions, influencing vascular remodeling by promoting SMC proliferation and suppressing endothelial gene expression across PAH subtypes. In patients with HPAH, pronounced immune dysregulation encircled PA walls, characterized by heightened perivascular inflammation involving T cell immunoglobulin and mucin domain-3 (TIM-3)+ T cells. This correlated with an expanded DC subset expressing indoleamine 2,3-dioxygenase 1, TIM-3, and SAM and HD domain-containing deoxynucleoside triphosphate triphosphohydrolase 1, alongside increased neutrophils, SMCs, and alpha-smooth muscle actin (ACTA2)+ endothelial cells, reinforcing the heightened severity of pulmonary vascular lesions. Conclusions: This study presents the first architectural map of PAH lungs, connecting immune subsets not only with specific PA lesions but also with heightened severity in HPAH compared with IPAH. Our findings emphasize the therapeutic potential of targeting monocyte-derived dendritic cells, neutrophils, cellular interactions, and immune responses to alleviate severe vascular pathology in IPAH and HPAH.

Pulmonary Hypertension and the Gut Microbiome

The gut microbiome and its associated metabolites are integral to the maintenance of gut integrity and function. There is increasing evidence that its alteration, referred to as dysbiosis, is involved in the development of a systemic conditions such as cardiovascular disease (e.g., systemic hypertension, atherosclerosis). Pulmonary hypertension (PH) is a condition characterised by progressive remodelling and vasoconstriction of the pulmonary circulation, ultimately leading to right ventricular failure and premature mortality if untreated. Initial studies have suggested a possible association between dysbiosis of the microbiome and the development of PH. The aim of this article is to review the current experimental and clinical data with respect to the potential interaction between the gut microbiome and the pathophysiology of pulmonary hypertension. It will also highlight possible new therapeutic targets that may provide future therapies.

Restoration of Foxp3+ Regulatory T Cells by HDAC-Dependent Epigenetic Modulation Plays a Pivotal Role in Resolving Pulmonary Arterial Hypertension Pathology

Rationale: Immune dysregulation is a common feature of pulmonary arterial hypertension (PAH). Histone deacetylase (HDAC)-dependent transcriptional reprogramming epigenetically modulates immune homeostasis and is a novel disease-oriented approach in modern times. Objectives: To identify a novel functional link between HDAC and regulatory T cells (Tregs) in PAH, aiming to establish disease-modified biomarkers and therapeutic targets. Methods: Peripheral blood mononuclear cells were isolated from patients with idiopathic PAH (IPAH) and rodent models of pulmonary hypertension (PH): monocrotaline rats, Sugen5416-hypoxia rats, and Treg-depleted mice. HDAC inhibitor vorinostat (suberoylanilide hydroxamic acid, SAHA) was used to examine the immune modulatory effects in vivo, ex vivo, and in vitro. Measurements and Main Results: Increased HDAC expression was associated with reduced Foxp3+ Tregs and increased PD-1 (programmed cell death-1) signaling in peripheral blood mononuclear cells from patients with IPAH. SAHA differentially modified a cluster of epigenetic-sensitive genes and induced Foxp3+ Treg conversion in IPAH T cells. Rodent models recapitulated these epigenetic aberrations and T-cell dysfunction. SAHA attenuated PH phenotypes and restored FOXP3 transcription and Tregs in PH rats; interestingly, the effects were more profound in female rats. Selective depletion of CD25+ Tregs in Sugen5416-hypoxia mice neutralized the effects of SAHA. Furthermore, SAHA inhibited endothelial cytokine/chemokine release upon stimulation and subsequent immune chemotaxis. Conclusions: Our results indicated HDAC aberration was associated with Foxp3+ Treg deficiency and demonstrated an epigenetic-mediated mechanism underlying immune dysfunction in PAH. Restoration of Foxp3+ Tregs by HDAC inhibitors is a promising approach to resolve pulmonary vascular pathology, highlighting the potential benefit of developing epigenetic therapies for PAH.

Identification of the shared gene signatures between pulmonary fibrosis and pulmonary hypertension using bioinformatics analysis

Pulmonary fibrosis (PF) and pulmonary hypertension (PH) have common pathophysiological features, such as the significant remodeling of pulmonary parenchyma and vascular wall. There is no effective specific drug in clinical treatment for these two diseases, resulting in a worse prognosis and higher mortality. This study aimed to screen the common key genes and immune characteristics of PF and PH by means of bioinformatics to find new common therapeutic targets. Expression profiles are downloaded from the Gene Expression Database. Weighted gene co-expression network analysis is used to identify the co-expression modules related to PF and PH. We used the ClueGO software to enrich and analyze the common genes in PF and PH and obtained the protein-protein interaction (PPI) network. Then, the differential genes were screened out in another cohort of PF and PH, and the shared genes were crossed. Finally, RT-PCR verification and immune infiltration analysis were performed on the intersection genes. In the result, the positive correlation module with the highest correlation between PF and PH was determined, and it was found that lymphocyte activation is a common feature of the pathophysiology of PF and PH. Eight common characteristic genes (ACTR2, COL5A2, COL6A3, CYSLTR1, IGF1, RSPO3, SCARNA17 and SEL1L) were gained. Immune infiltration showed that compared with the control group, resting CD4 memory T cells were upregulated in PF and PH. Combining the results of crossing characteristic genes in ImmPort database and RT-PCR, the important gene IGF1 was obtained. Knocking down IGF1 could significantly reduce the proliferation and apoptosis resistance in pulmonary microvascular endothelial cells, pulmonary smooth muscle cells, and fibroblasts induced by hypoxia, platelet-derived growth factor-BB (PDGF-BB), and transforming growth factor-β1 (TGF-β1), respectively. Our work identified the common biomarkers of PF and PH and provided a new candidate gene for the potential therapeutic targets of PF and PH in the future.

Perivascular inflammatory cells and their association with pulmonary arterial remodelling in dogs with pulmonary hypertension due to myxomatous mitral valve disease

Pulmonary hypertension (PH), an increase in pulmonary arterial pressure (PAP), may occur in dogs affected with myxomatous mitral valve disease (MMVD). Recent studies suggest that an accumulation of perivascular inflammatory cells may be involved with medial thickening which is a sign of the pulmonary artery remodelling in PH. The aim of this study was to characterise perivascular inflammatory cells in the surrounding pulmonary arteries of dogs with PH due to MMVD compared to MMVD dogs and healthy control dogs. Nineteen lung samples were collected from cadavers of small-breed dogs (control n = 5; MMVD n = 7; MMVD + PH n = 7). Toluidine blue stain and multiple IHC targeting α-SMA, vWF, CD20, CD68 and CD3 was performed to examine intimal and medial thickening, assess muscularisation of the small pulmonary arteries and characterise perivascular leucocytes. Medial thickening without intimal thickening of pulmonary arteries and muscularisation of normally non-muscularised small pulmonary arteries was observed in the MMVD and MMVD + PH groups compared with the control group. The perivascular numbers of B lymphocytes, T lymphocytes and macrophages was significantly increased in the MMVD + PH group compared with the MMVD and control groups. In contrast, the perivascular number of mast cells was significantly higher in the MMVD group compared with the MMVD + PH and control groups. This study suggested that pulmonary artery remodelling as medial thickening and muscularisation of the normally non-muscular small pulmonary arteries is accompanied by the accumulation of perivascular inflammatory cells.

The impact of microbiota-derived short-chain fatty acids on macrophage activities in disease: Mechanisms and therapeutic potentials

Short-chain fatty acids (SCFAs) derived from the fermentation of carbohydrates by gut microbiota play a crucial role in regulating host physiology. Among them, acetate, propionate, and butyrate are key players in various biological processes. Recent research has revealed their significant functions in immune and inflammatory responses. For instance, butyrate reduces the development of interferon-gamma (IFN-γ) generating cells while promoting the development of regulatory T (Treg) cells. Propionate inhibits the initiation of a Th2 immune response by dendritic cells (DCs). Notably, SCFAs have an inhibitory impact on the polarization of M2 macrophages, emphasizing their immunomodulatory properties and potential for therapeutics. In animal models of asthma, both butyrate and propionate suppress the M2 polarization pathway, thus reducing allergic airway inflammation. Moreover, dysbiosis of gut microbiota leading to altered SCFA production has been implicated in prostate cancer progression. SCFAs trigger autophagy in cancer cells and promote M2 polarization in macrophages, accelerating tumor advancement. Manipulating microbiota- producing SCFAs holds promise for cancer treatment. Additionally, SCFAs enhance the expression of hypoxia-inducible factor 1 (HIF-1) by blocking histone deacetylase, resulting in increased production of antibacterial effectors and improved macrophage-mediated elimination of microorganisms. This highlights the antimicrobial potential of SCFAs and their role in host defense mechanisms. This comprehensive review provides an in-depth analysis of the latest research on the functional aspects and underlying mechanisms of SCFAs in relation to macrophage activities in a wide range of diseases, including infectious diseases and cancers. By elucidating the intricate interplay between SCFAs and macrophage functions, this review aims to contribute to the understanding of their therapeutic potential and pave the way for future interventions targeting SCFAs in disease management.

Pharmacology and Rationale for Seralutinib in the Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a complex disorder characterized by vascular remodeling and a consequent increase in pulmonary vascular resistance. The histologic hallmarks of PAH include plexiform and neointimal lesions of the pulmonary arterioles, which are composed of dysregulated, apoptosis-resistant endothelial cells and myofibroblasts. Platelet-derived growth factor receptors (PDGFR) α and β, colony stimulating factor 1 receptor (CSF1R), and mast/stem cell growth factor receptor kit (c-KIT) are closely related kinases that have been implicated in PAH progression. In addition, emerging data indicate significant crosstalk between PDGF signaling and the bone morphogenetic protein receptor type 2 (BMPR2)/transforming growth factor β (TGFβ) receptor axis. This review will discuss the importance of the PDGFR-CSF1R-c-KIT signaling network in PAH pathogenesis, present evidence that the inhibition of all three nodes in this kinase network is a potential therapeutic approach for PAH, and highlight the therapeutic potential of seralutinib, currently in development for PAH, which targets these pathways.

Immunoregulatory macrophages modify local pulmonary immunity and ameliorate hypoxic-pulmonary hypertension

Rationale

Macrophages play a central role in the onset and progression of vascular disease in pulmonary hypertension (PH) and cell-based immunotherapies aimed at treating vascular remodeling are lacking.

Objective

To evaluate the effect of pulmonary administration of macrophages modified to have an anti-inflammatory/pro-resolving phenotype in attenuating early pulmonary inflammation and progression of experimentally induced PH.

Methods

Mouse bone marrow derived macrophages (BMDMs) were polarized in vitro to a regulatory (M2 reg ) phenotype. M2 reg profile and anti-inflammatory capacity were assessed in vitro upon lipopolysaccharide (LPS)/interferon-γ (IFNγ) restimulation, before their administration to 8- to 12-week-old mice. M2 reg protective effect was tested at early (2 to 4 days) and late (4 weeks) time points during hypoxia (8.5% O 2 ) exposure. Levels of inflammatory markers were quantified in alveolar macrophages and whole lung, while PH development was ascertained by right ventricular systolic pressure (RSVP) and right ventricular hypertrophy (RVH) measurements. Bronchoalveolar lavage (BAL) from M2 reg -transplanted hypoxic mice was collected, and its inflammatory potential tested on naïve BMDMs.

Results

M2 reg macrophages demonstrated a stable anti-inflammatory phenotype upon a subsequent pro-inflammatory stimulus by maintaining the expression of specific anti-inflammatory markers (Tgfß, Il10 and Cd206) and downregulating the induction of proinflammatory cytokines and surface molecules (Cd86, Il6 and Tnfα). A single dose of M2 regs attenuated the hypoxic monocytic recruitment and perivascular inflammation. Early hypoxic lung and alveolar macrophage inflammation leading to PH development was significantly reduced and, importantly, M2 regs attenuated RVH, RVSP and vascular remodeling at 4 weeks post treatment.

Conclusions

Adoptive transfer of M2 regs halts the recruitment of monocytes and modifies the hypoxic lung microenvironment, potentially changing the immunoreactivity of recruited macrophages and restoring normal immune functionality of the lung. These findings provide new mechanistic insights on the diverse role of macrophage phenotype on lung vascular homeostasis that can be explored as novel therapeutic targets.

Microenvironmental regulation of T-cells in pulmonary hypertension

Introduction

In pulmonary hypertension (PH), pulmonary arterial remodeling is often accompanied by perivascular inflammation. The inflammation is characterized by the accumulation of activated macrophages and lymphocytes within the adventitial stroma, which is comprised primarily of fibroblasts. The well-known ability of fibroblasts to secrete interleukins and chemokines has previously been implicated as contributing to this tissue-specific inflammation in PH vessels. We were interested if pulmonary fibroblasts from PH arteries contribute to microenvironmental changes that could activate and polarize T-cells in PH.

Methods

We used single-cell RNA sequencing of intact bovine distal pulmonary arteries (dPAs) from PH and control animals and flow cytometry, mRNA expression analysis, and respirometry analysis of blood-derived bovine/human T-cells exposed to conditioned media obtained from pulmonary fibroblasts of PH/control animals and IPAH/control patients (CM-(h)PH Fibs vs CM-(h)CO Fibs).

Results

Single-cell RNA sequencing of intact bovine dPAs from PH and control animals revealed a pro-inflammatory phenotype of CD4+ T-cells and simultaneous absence of regulatory T-cells (FoxP3+ Tregs). By exposing T-cells to CM-(h)PH Fibs we stimulated their proinflammatory differentiation documented by increased IFNγ and decreased IL4, IL10, and TGFβ mRNA and protein expression. Interestingly, we demonstrated a reduction in the number of suppressive T-cell subsets, i.e., human/bovine Tregs and bovine γδ T-cells treated with CM-(h)PH-Fibs. We also noted inhibition of anti-inflammatory cytokine expression (IL10, TGFβ, IL4). Pro-inflammatory polarization of bovine T-cells exposed to CM-PH Fibs correlated with metabolic shift to glycolysis and lactate production with increased prooxidant intracellular status as well as increased proliferation of T-cells. To determine whether metabolic reprogramming of PH-Fibs was directly contributing to the effects of PH-Fibs conditioned media on T-cell polarization, we treated PH-Fibs with the HDAC inhibitor SAHA, which was previously shown to normalize metabolic status and examined the effects of the conditioned media. We observed significant suppression of inflammatory polarization associated with decreased T-cell proliferation and recovery of mitochondrial energy metabolism.

Conclusion

This study demonstrates how the pulmonary fibroblast-derived microenvironment can activate and differentiate T-cells to trigger local inflammation, which is part of the vascular wall remodeling process in PH.

Inflammation and DKK1-induced AKT activation contribute to endothelial dysfunction following NR2F2 loss

NR2F2 is expressed in endothelial cells (ECs) and Nr2f2 knockout produces lethal cardiovascular defects. In humans, reduced NR2F2 expression is associated with cardiovascular diseases including congenital heart disease and atherosclerosis. Here, NR2F2 silencing in human primary ECs led to inflammation, endothelial-to-mesenchymal transition (EndMT), proliferation, hypermigration, apoptosis-resistance, and increased production of reactive oxygen species. These changes were associated with STAT and AKT activation along with increased production of DKK1. Co-silencing DKK1 and NR2F2 prevented NR2F2-loss-induced STAT and AKT activation and reversed EndMT. Serum DKK1 concentrations were elevated in patients with pulmonary arterial hypertension (PAH) and DKK1 was secreted by ECs in response to in vitro loss of either BMPR2 or CAV1, which are genetic defects associated with the development of PAH. In human primary ECs, NR2F2 suppressed DKK1, whereas its loss conversely induced DKK1 and disrupted endothelial homeostasis, promoting phenotypic abnormalities associated with pathologic vascular remodeling. Activating NR2F2 or blocking DKK1 may be useful therapeutic targets for treating chronic vascular diseases associated with EC dysfunction.NEW & NOTEWORTHY NR2F2 loss in the endothelial lining of blood vessels is associated with cardiovascular disease. Here, NR2F2-silenced human endothelial cells were inflammatory, proliferative, hypermigratory, and apoptosis-resistant with increased oxidant stress and endothelial-to-mesenchymal transition. DKK1 was induced in NR2F2-silenced endothelial cells, while co-silencing NR2F2 and DKK1 prevented NR2F2-loss-associated abnormalities in endothelial signaling and phenotype. Activating NR2F2 or blocking DKK1 may be useful therapeutic targets for treating vascular diseases associated with endothelial dysfunction.

Pulmonary vascular fibrosis in pulmonary hypertension - The role of the extracellular matrix as a therapeutic target

Pulmonary hypertension (PH) is a condition characterized by changes in the extracellular matrix (ECM) deposition and vascular remodeling of distal pulmonary arteries. These changes result in increased vessel wall thickness and lumen occlusion, leading to a loss of elasticity and vessel stiffening. Clinically, the mechanobiology of the pulmonary vasculature is becoming increasingly recognized for its prognostic and diagnostic value in PH. Specifically, the increased vascular fibrosis and stiffening resulting from ECM accumulation and crosslinking may be a promising target for the development of anti- or reverse-remodeling therapies. Indeed, there is a huge potential in therapeutic interference with mechano-associated pathways in vascular fibrosis and stiffening. The most direct approach is aiming to restore extracellular matrix homeostasis, by interference with its production, deposition, modification and turnover. Besides structural cells, immune cells contribute to the level of ECM maturation and degradation by direct cell-cell contact or the release of mediators and proteases, thereby opening a huge avenue to target vascular fibrosis via immunomodulation approaches. Indirectly, intracellular pathways associated with altered mechanobiology, ECM production, and fibrosis, offer a third option for therapeutic intervention. In PH, a vicious cycle of persistent activation of mechanosensing pathways such as YAP/TAZ initiates and perpetuates vascular stiffening, and is linked to key pathways disturbed in PH, such as TGF-beta/BMPR2/STAT. Together, this complexity of the regulation of vascular fibrosis and stiffening in PH allows the exploration of numerous potential therapeutic interventions. This review discusses connections and turning points of several of these interventions in detail.