Immunoglobulin-driven Complement Activation Regulates Proinflammatory Remodeling in Pulmonary Hypertension

When cell teamwork turns toxic

In pulmonary hypertension, a combination of metabolic and mechanical dysfunction leads to irreversible vascular damage.

Adventitial fibroblasts direct smooth muscle cell-state transition in pulmonary vascular disease

Background

Pulmonary vascular remodeling is a progressive pathological process characterized by functional alterations within pulmonary artery smooth muscle cells (PASMCs) and adventitial fibroblasts (PAAFs). Mechanisms driving the transition to a diseased phenotype remain elusive.

Methods

We combined transcriptomic and proteomic profiling with phenotypic characterization of source-matched cells from healthy controls and individuals with idiopathic pulmonary arterial hypertension (IPAH). Bidirectional cellular crosstalk was examined using direct and indirect co-culture models, and phenotypic responses were assessed via transcriptome analysis.

Results

PASMC and PAAF undergo distinct phenotypic shifts during pulmonary vascular remodeling, with limited shared features, such as reduced mitochondrial content and hyperpolarization. IPAH-PASMC exhibit increased glycosaminoglycan production and downregulation of contractile machinery, while IPAH-PAAF display a hyperproliferative phenotype. We identified alterations in extracellular matrix components, including laminin and collagen, alongside pentraxin-3 and hepatocyte growth factor, as potential regulators of PASMC phenotypic transitions mediated by PAAF.

Conclusions

While PASMCs and PAAFs retain their core cellular identities, they acquire distinct disease-associated states. These findings provide new insights into the dynamic interplay of pulmonary vascular mesenchymal cells in disease pathogenesis.

Funding

This work was supported by Cardio-Pulmonary Institute EXC 2026 390649896 (GK) and Austrian Science Fund (FWF) grant I 4651-B (SC).

Using network analysis to identify central symptoms of depression and anxiety in different profiles of infertility patients

BACKGROUND

Depression and anxiety were not only common but also with serious consequence in infertility patients. The current study endeavors to define distinct depression and anxiety profiles of infertility patients and identify central symptoms within different profiles to facilitate targeted interventions.

METHOD

The research employed K-means Clustering to delineate the depression and anxiety profiles, followed by a repetition of the analysis using Latent Class Analysis (LCA). Furthermore, network analysis was utilized to identify central symptoms within the various profiles.

RESULT

K‑means Clustering identified Cluster 1 (16.15%), Cluster 2 (37.08%) and Cluster 3 (46.77%), while LCA yielded the low-risk group (47.23%), the mild-risk group (34.46%) and the high-risk group (18.31%). A majority of patients in the three clusters were predominantly in a single LCA-derived patient class (88.38-100%). Network analysis revealed that connections within each symptom in PHQ-9 and GAD-7 were stronger than those between symptoms. Furthermore, PHQ 2 ("sad mood"), GAD 1 ("nervousness") and GAD 2 ("uncontrollable worry") were identified as the central symptoms in Cluster 1 GAD 3 ("excessive worry"), GAD 2 ("uncontrollable worry") and GAD 5 ("restlessness") emerged as the central symptoms in Cluster 2) Additionally, PHQ 4 ("fatigue"), GAD 6 ("irritability") and GAD 3 ("excessive worry") were identified as the central symptoms in Cluster 3.

CONCLUSIONS

We defined three distinct depression and anxiety profiles among infertility patients and pinpointed central symptoms within each profile. These findings underscore the importance of directing research towards those central symptoms within each profile in order to develop targeted intervention strategies.

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 noncoding RNAs (lncRNAs), 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 coexpression network analysis 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 demonstrated that SNHG11 plays a critical role in modulating inflammation, cell proliferation, apoptosis, and the Janus kinase/signal transducers and activators of transcription and mitogen-activated protein kinase 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.

An intracellular complement system drives metabolic and proinflammatory reprogramming of vascular fibroblasts in pulmonary hypertension

The complement system is central to the innate immune response, playing a critical role in proinflammatory and autoimmune diseases such as pulmonary hypertension (PH). Recent discoveries highlight the emerging role of intracellular complement, or the "complosome," in regulating cellular processes such as glycolysis, mitochondrial dynamics, and inflammatory gene expression. This study investigated the hypothesis that intracellular complement proteins C3, CFB, and CFD are upregulated in PH fibroblasts (PH-Fibs) and drive their metabolic and inflammatory states, contributing to PH progression. Our results revealed a pronounced upregulation of CFD, CFB, and C3 in PH-Fibs from human samples and bovine models, both in vivo and in vitro. The finding of elevated levels of C3 activation fragments, including C3b, C3d, and C3a, emphasized enhanced C3 activity. PH-Fibs exhibited notable metabolic reprogramming and increased levels of proinflammatory mediators such as MCP1, SDF1, IL-6, IL-13, and IL-33. Silencing CFD via shRNA reduced CFB activation and C3a production, while normalizing glycolysis, tricarboxylic acid (TCA) cycle activity, and fatty acid metabolism. Metabolomic and gene expression analyses of CFD-knockdown PH-Fibs revealed restored metabolic and inflammatory profiles, underscoring CFD's crucial role in these changes. This study emphasizes the crucial role of intracellular complement in PH pathogenesis, highlighting the potential for complement-targeted therapies in PH.

Identification of an immune-related gene panel for the diagnosis of pulmonary arterial hypertension using bioinformatics and machine learning

OBJECTIVE

This study aimed to screen an immune-related gene (IRG) panel and develop a novel approach for diagnosing pulmonary arterial hypertension (PAH) utilizing bioinformatics and machine learning (ML).

METHODS

Gene expression profiles were retrieved from the Gene Expression Omnibus (GEO) database to identify differentially expressed immune-related genes (IRG-DEGs). We employed five machine learning algorithms-LASSO, random forest (RF), boosted regression trees (BRT), XGBoost, and support vector machine recursive feature elimination (SVM-RFE) to identify biomarkers derived from IRG-DEGs associated with the diagnosis of PAH, incorporating them into the IRG-DEGs panel. Validation of these biomarker levels in lung tissue was conducted in a hypoxia-induced mouse model of PAH, investigating the correlation between AIMP1, IL-15, GLRX, SOD1, Fulton's index (RVHI), and the ratio of pulmonary artery medial thickness to external diameter (MT%). Subsequently, we developed a nomogram model based on the IRG-DEGs panel in lung tissue for diagnosing PAH. The expression, distribution, and pseudotime analysis of these biomarkers across various immune cell types were assessed using single-cell sequencing datasets. Finally, we evaluated the diagnostic utility of the nomogram model based on the IRG-DEGs panel in peripheral blood mononuclear cells (PBMCs) for diagnosing PAH.

RESULTS

A total of 36 upregulated and 17 downregulated IRG-DEGs were identified in lung tissue from patients with PAH. AIMP1, IL-15, GLRX, and SOD1 were subsequently selected as novel immune-related biomarkers for PAH through the aforementioned machine learning algorithms and incorporated into the IRG-DEGs panel. Experimental results from mice with PAH validated that the expression levels of AIMP1, IL-15, and GLRX in lung tissue were elevated, while SOD1 expression was significantly reduced. Additionally, GLRX and AIMP1 exhibited positive correlations with Fulton's index (RVHI). The expression levels of GLRX, IL-15, and AIMP1 showed positive correlations with MT%, whereas SOD1 exhibited negative correlations with MT%. Analysis of single-cell sequencing data further revealed that the levels of IRG-DEG panel members gradually increased during the pseudotime trajectory from PBMCs to macrophages, correlating with macrophage activation. The area under the curve (AUC) for diagnosing PAH using a nomogram model based on the IRG-DEGs panel derived from lung tissue samples and PBMCs was ≥0.969 and 0.900, respectively.

CONCLUSIONS

We developed an IRG-DEGs panel containing AIMP1, IL-15, GLRX, and SOD1, which may facilitate the diagnosis of pulmonary arterial hypertension (PAH). These findings provide novel insights that may enhance diagnostic and therapeutic approaches for PAH.

Utility of factor D and other alternative complement factors as biomarkers in systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH)

BACKGROUND

Activation of the complement cascade is thought to play a role in scleroderma vasculopathy. We previously showed that complement factor D was elevated in patients with limited cutaneous SSc and pulmonary arterial hypertension (PAH). In this study, we sought to assess multiple relevant components of the complement cascade to determine if they are altered in SSc-PAH, as well as their potential utility as biomarkers of disease severity and progression.

METHODS

Complement components (n = 14) were measured using multiplex assays in 156 patients with SSc-PAH from a multi-site repository and were compared to 33 patients with SSc without PAH, and 40 healthy controls. Data were evaluated for correlations between complement levels, right heart catheterization measures, and clinical endpoints including 6-minute walk distance. To assess complement longitudinally, serum complement levels were assayed at 0, 4, 12, 24, 36 and 48 weeks in 52 SSc-PAH patients who participated in a prior clinical trial.

RESULTS

We found that factor D was significantly elevated in SSc-PAH compared to SSc without PAH (p < 0.0001) and was highly sensitive and specific for SSc-PAH (AUC=0.82, p < 0.001). In SSc-PAH patients, alterations in factor H, C4, and factor D were associated with measures of PAH disease severity including right heart catheterization measurements (cardiac output, right atrial pressure, and VO2 max), survival, and 6-minute walk distance. No significant changes in complement levels or clinical associations were seen over time or associated with treatment in the longitudinal clinical trial study.

CONCLUSION

Our work confirms prior studies demonstrating a role for complement activation in SSc vascular disease and elevations of factor D in a large SSc-PAH population. Further, factor H and other complement factors are associated with severity of PAH including mortality. Taken together, these findings suggest that the alternative complement pathway plays a role in SSc-PAH pathogenesis and may serve as a biomarker to inform diagnosis and prognosis.

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.

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.

Complement factor B, not the membrane attack complex component C9, promotes neointima formation after arterial wire injury

BACKGROUND AND AIMS

Vascular restenosis due to neointima hyperplasia limits the long-term patency of stented arteries, resulting in angioplasty failure. The complement system has been implicated in restenosis. This study aimed to investigate the role of complement factor B (fB), an essential component of the alternative pathway of complement activation, in neointima formation.

METHODS

Angioplasty wire injury was conducted using 12-week-old mice deficient in fB or C9 (the main component of the membrane attacking complex, C5b-9) and littermate controls and neointima formation were assessed. Vascular smooth muscle cell (SMC) and endothelial cell (EC) proliferation and migration were examined in vitro.

RESULTS

fB was mainly detected in SMCs of stenotic arteries from humans and mice. Deletion of fB substantially reduced the neointima area and intima-to-media area ratio without affecting the media area at 28 days after injury. At 7 days after injury, fB deficiency decreased SMC proliferation, unaltering neointimal macrophage infiltration and EC reendothelialization. Vascular SMC-expressed fB, not the circulation-sourced fB, played an essential role in SMC proliferation and migration in vitro. fB deficient mice exhibited lower levels of the soluble form of C5b-9, however, deletion of C9 did not alter neointima formation after wire injury, consistent with the null impact of C9 deficiency on SMC proliferation in vitro.

CONCLUSIONS

fB promotes neointima formation following wire-induced artery injury independent of forming the membrane-attacking complex. This is attributable to fB-dependent SMC proliferation and migration without affecting EC function. Targeting fB might protect against restenosis after percutaneous coronary intervention.

Complement Immune System in Pulmonary Hypertension-Cooperating Roles of Circadian Rhythmicity in Complement-Mediated Vascular Pathology

Originally discovered in the 1890s, the complement system has traditionally been viewed as a "compliment" to the body's innate and adaptive immune response. However, emerging data have shown that the complement system is a much more complex mechanism within the body involved in regulating inflammation, gene transcription, attraction of macrophages, and many more processes. Sustained complement activation contributes to autoimmunity and chronic inflammation. Pulmonary hypertension is a disease with a poor prognosis and an average life expectancy of 2-3 years that leads to vascular remodeling of the pulmonary arteries; the pulmonary arteries are essential to host homeostasis, as they divert deoxygenated blood from the right ventricle of the heart to the lungs for gas exchange. This review focuses on direct links between the complement system's involvement in pulmonary hypertension, along with autoimmune conditions, and the reliance on the complement system for vascular remodeling processes of the pulmonary artery. Furthermore, circadian rhythmicity is highlighted as the disrupted homeostatic mechanism in the inflammatory consequences in the vascular remodeling within the pulmonary arteries, which could potentially open new therapeutic cues. The current treatment options for pulmonary hypertension are discussed with clinical trials using complement inhibitors and potential therapeutic targets that impact immune cell functions and complement activation, which could alleviate symptoms and block the progression of the disease. Further research on complement's involvement in interstitial lung diseases and pulmonary hypertension could prove beneficial for our understanding of these various diseases and potential treatment options to prevent vascular remodeling of the pulmonary arteries.

Ferroptosis-Mediated Inflammation Promotes Pulmonary Hypertension

BACKGROUND

Mitochondrial dysfunction, characterized by impaired lipid metabolism and heightened reactive oxygen species generation, results in lipid peroxidation and ferroptosis. Ferroptosis is an inflammatory mode of cell death that promotes complement activation and macrophage recruitment. In pulmonary arterial hypertension (PAH), pulmonary arterial endothelial cells exhibit cellular phenotypes that promote ferroptosis. Moreover, there is ectopic complement deposition and inflammatory macrophage accumulation in the pulmonary vasculature. However, the effects of ferroptosis inhibition on these pathogenic mechanisms and the cellular landscape of the pulmonary vasculature are incompletely defined.

METHODS

Multiomics and physiological analyses evaluated how ferroptosis inhibition-modulated preclinical PAH. The impact of adeno-associated virus 1-mediated expression of the proferroptotic protein ACSL (acyl-CoA synthetase long-chain family member) 4 on PAH was determined, and a genetic association study in humans further probed the relationship between ferroptosis and pulmonary hypertension.

RESULTS

Ferrostatin-1, a small-molecule ferroptosis inhibitor, mitigated PAH severity in monocrotaline rats. RNA-sequencing and proteomics analyses demonstrated ferroptosis was associated with PAH severity. RNA-sequencing, proteomics, and confocal microscopy revealed complement activation and proinflammatory cytokines/chemokines were suppressed by ferrostatin-1. In addition, ferrostatin-1 combatted changes in endothelial, smooth muscle, and interstitial macrophage abundance and gene activation patterns as revealed by deconvolution RNA-sequencing. Ferroptotic pulmonary arterial endothelial cell damage-associated molecular patterns restructured the transcriptomic signature and mitochondrial morphology, promoted the proliferation of pulmonary artery smooth muscle cells, and created a proinflammatory phenotype in monocytes in vitro. Adeno-associated virus 1-Acsl4 induced an inflammatory PAH phenotype in rats. Finally, single-nucleotide polymorphisms in 6 ferroptosis genes identified a potential link between ferroptosis and pulmonary hypertension severity in the Vanderbilt BioVU repository.

CONCLUSIONS

Ferroptosis promotes PAH through metabolic and inflammatory mechanisms in the pulmonary vasculature.

Activation of platelets and the complement system in mice with Schistosoma-induced pulmonary hypertension

Schistosomiasis-induced pulmonary hypertension (PH) presents a significant global health burden, yet the underlying mechanisms remain poorly understood. Here, we investigate the involvement of platelets and the complement system in the initiation events leading to Schistosoma-induced PH. We demonstrate that Schistosoma exposure leads to thrombocytopenia, platelet accumulation in the lung, and platelet activation. In addition, we observed increased plasma complement anaphylatoxins C3a and C5a, indicative of complement system activation, and elevated platelet expression of C1q, C3, decay activating factor (DAF), and complement C3a and C5a receptors. Our findings suggest the active involvement of platelets in responding to complement system signals induced by Schistosoma exposure and form the basis for future mechanistic studies on how complement may regulate platelet activation and promote the development of Schistosoma-induced PH.NEW & NOTEWORTHY Schistosomiasis-induced pulmonary hypertension (PH) is a significant global health burden, yet the underlying mechanisms remain poorly understood. We demonstrate that Schistosoma exposure leads to platelet accumulation in the lung and platelet activation. We observed increased plasma levels of C3a and C5a, indicative of complement system activation, and elevated expression of platelet complement proteins and receptors. These findings underscore the role of platelets and complement in the inflammatory responses associated with Schistosoma-induced PH.

MSC-derived exosomes attenuates pulmonary hypertension via inhibiting pulmonary vascular remodeling

BACKGROUND

Pulmonary hypertension (PH) is a serious cardiopulmonary disease with significant morbidity and mortality. Vascular obstruction leads to a continuous increase in pulmonary vascular resistance, vascular remodeling, and right ventricular hypertrophy and failure, which are the main pathological features of PH. Currently, the treatments for PH are very limited, so new methods are urgently needed. Msenchymal stem cells-derived exosomes have been shown to have significant therapeutic effects in PH, however, the mechanism still very blurry. Here, we investigated the possible mechanism by which umbilical cord mesenchymal stem cell-derived exosomes (hUC-MSC-EXO) inhibited monocrotaline (MCT)-induced pulmonary vascular remodeling in a rat model of PH by regulating the NF-κB/BMP signaling pathway. Our data revealed that hUC-MSC-EXO could significantly attenuate MCT-induced PH and right ventricular hypertrophy. Moreover, the protein expression level of BMPR2, BMP-4, BMP-9 and ID1 was significantly increased, but NF-κB p65, p-NF-κB-p65 and BMP antagonists Gremlin-1 was increased in vitro and vivo. Collectively, this study revealed that the mechanism of hUC-MSC-EXO attenuates pulmonary hypertension may be related to inhibition of NF-κB signaling to further activation of BMP signaling. The present study provided a promising therapeutic strategy for PH vascular remodeling.

Pulmonary artery smooth muscle cell pyroptosis promotes the proliferation of PASMCs by paracrine IL‑1β and IL‑18 in monocrotaline‑induced pulmonary arterial hypertensive rats

Pulmonary arterial hypertension (PAH) is a common vascular disease, and pulmonary vascular remodeling is a pivotal pathophysiological mechanism of PAH. Major pathological changes of pulmonary arterial remodeling, including proliferation, hypertrophy and enhanced secretory activity, can occur in pulmonary artery smooth muscle cells (PASMCs). Multiple active factors and cytokines play important roles in PAH. However, the regulatory mechanisms of the active factors and cytokines in PAH remain unclear. The present study aimed to reveal the crucial role of PASMC pyroptosis in PAH and to elucidate the intrinsic mechanisms. To establish the PAH rat models, Sprague-Dawley rats were injected intraperitoneally with monocrotaline (MCT) at a dose of 60 mg/kg. The expression of proteins and interleukins were detected by western blotting and ELISA assay. The results indicated that the pyroptosis of PASMCs is significantly increased in MCT-induced PAH rats. Notably, pyroptotic PASMCs can secret IL-1β and IL-18 to promote the proliferation of PASMCs. On this basis, inhibiting the secretion of IL-1β and IL-18 can markedly inhibit PASMC proliferation. Collectively, the findings of the present study indicate a critical role for PASMC pyroptosis in MCT-induced PAH rats, prompting a new preventive and therapeutic strategy for PAH.

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.

Genomic Insights into the Role of TOP Gene Family in Soft-Tissue Sarcomas: Implications for Prognosis and Therapy

This study focuses on the role of topoisomerases (TOPs) in sarcomas (SARCs), highlighting TOPs' influence on sarcoma prognosis through mRNA expression, genetic mutations, immune infiltration, and DNA methylation analysis using transcriptase sequencing and other techniques. The findings indicate that TOP gene mutations correlate with increased inflammation, immune cell infiltration, DNA repair abnormalities, and mitochondrial fusion genes alterations, all of which negatively affect sarcoma prognosis. Abnormal TOP expression may independently affect sarcoma patients' survival. Cutting-edge genomic tools such as Oncomine, gene expression profiling interactive analysis (GEPIA), and cBio Cancer Genomics Portal (cBioPortal) are utilized to explore the TOP gene family (TOP1/1MT/2A/2B/3A/3B) in soft-tissue sarcomas (STSs). This in-depth analysis reveals a notable upregulation of TOP mRNA in STS patients arcoss various SARC subtypes, French Federation Nationale des Centres de Lutte Contre le Cancer classification (FNCLCC) grades, and specific molecular profiles correlating with poorer clinical outcomes. Furthermore, this investigation identifies distinct patterns of immune cell infiltration, genetic mutations, and somatic copy number variations linked to TOP genes that inversely affect patient survival rates. These findings underscore the diagnostic and therapeutic relevance of the TOP gene suite in STSs.

Preliminary Mechanism of Glial Maturation Factor β on Pulmonary Vascular Remodeling in Pulmonary Arterial Hypertension

Recent evidence suggests that glia maturation factor β (GMFβ) is important in the pathogenesis of pulmonary arterial hpertension (PAH), but the underlying mechanism is unknown. To clarify whether GMFβ can be involved in pulmonary vascular remodeling and to explore the role of the IL-6-STAT3 pathway in this process, the expression of GMFβ in PAH rats is examined and the expression of downstream molecules including periostin (POSTN) and interleukin-6 (IL-6) is measured using real-time quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. The location and expression of POSTN is also tested in PAH rats using immunofluorescence. It is proved that GMFβ is upregulated in the lungs of PAH rats. Knockout GMFβ alleviated the MCT-PAH by reducing right ventricular systolic pressure (RVSP), mean pulmonary arterial pressure (mPAP), and pulmonary vascular remodeling. Moreover, the inflammation of the pulmonary vasculature is ameliorated in PAH rats with GMFβ absent. In addition, the IL-6-STAT3 signaling pathway is activated in PAH; knockout GMFβ reduced POSTN and IL-6 production by inhibiting the IL-6-STAT3 signaling pathway. Taken together, these findings suggest that knockout GMFβ ameliorates PAH in rats by inhibiting the IL-6-STAT3 signaling pathway.

Single cell transcriptomic analyses reveal diverse and dynamic changes of distinct populations of lung interstitial macrophages in hypoxia-induced pulmonary hypertension

Introduction

Hypoxia is a common pathological driver contributing to various forms of pulmonary vascular diseases leading to pulmonary hypertension (PH). Pulmonary interstitial macrophages (IMs) play pivotal roles in immune and vascular dysfunction, leading to inflammation, abnormal remodeling, and fibrosis in PH. However, IMs' response to hypoxia and their role in PH progression remain largely unknown. We utilized a murine model of hypoxia-induced PH to investigate the repertoire and functional profiles of IMs in response to acute and prolonged hypoxia, aiming to elucidate their contributions to PH development.

Methods

We conducted single-cell transcriptomic analyses to characterize the repertoire and functional profiles of murine pulmonary IMs following exposure to hypobaric hypoxia for varying durations (0, 1, 3, 7, and 21 days). Hallmark pathways from the mouse Molecular Signatures Database were utilized to characterize the molecular function of the IM subpopulation in response to hypoxia.

Results

Our analysis revealed an early acute inflammatory phase during acute hypoxia exposure (Days 1-3), which was resolved by Day 7, followed by a pro-remodeling phase during prolonged hypoxia (Days 7-21). These phases were marked by distinct subpopulations of IMs: MHCIIhiCCR2+EAR2+ cells characterized the acute inflammatory phase, while TLF+VCAM1hi cells dominated the pro-remodeling phase. The acute inflammatory phase exhibited enrichment in interferon-gamma, IL-2, and IL-6 pathways, while the pro-remodeling phase showed dysregulated chemokine production, hemoglobin clearance, and tissue repair profiles, along with activation of distinct complement pathways.

Discussion

Our findings demonstrate the existence of distinct populations of pulmonary interstitial macrophages corresponding to acute and prolonged hypoxia exposure, pivotal in regulating the inflammatory and remodeling phases of PH pathogenesis. This understanding offers potential avenues for targeted interventions, tailored to specific populations and distinct phases of the disease. Moreover, further identification of triggers for pro-remodeling IMs holds promise in unveiling novel therapeutic strategies for pulmonary hypertension.

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

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

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.

Novel insights and new therapeutic potentials for macrophages in pulmonary hypertension

Inflammation and immune processes underlie pulmonary hypertension progression. Two main different activated phenotypes of macrophages, classically activated M1 macrophages and alternatively activated M2 macrophages, are both involved in inflammatory processes related to pulmonary hypertension. Recent advances suggest that macrophages coordinate interactions among different proinflammatory and anti-inflammatory mediators, and other cellular components such as smooth muscle cells and fibroblasts. In this review, we summarize the current literature on the role of macrophages in the pathogenesis of pulmonary hypertension, including the origin of pulmonary macrophages and their response to triggers of pulmonary hypertension. We then discuss the interactions among macrophages, cytokines, and vascular adventitial fibroblasts in pulmonary hypertension, as well as the potential therapeutic benefits of macrophages in this disease. Identifying the critical role of macrophages in pulmonary hypertension will contribute to a comprehensive understanding of this pathophysiological abnormality, and may provide new perspectives for pulmonary hypertension management.

A novel complement C3 inhibitor CP40-KK protects against experimental pulmonary arterial hypertension via an inflammasome NLRP3 associated pathway

BACKGROUND

Pulmonary arterial hypertension (PAH) is a severe cardiopulmonary disease characterized by complement dependent and proinflammatory activation of macrophages. However, effective treatment for complement activation in PAH is lacking. We aimed to explore the effect and mechanism of CP40-KK (a newly identified analog of selective complement C3 inhibitor CP40) in the PAH model.

METHODS

We used western blotting, immunohistochemistry, and immunofluorescence staining of lung tissues from the monocrotaline (MCT)-induced rat PAH model to study macrophage infiltration, NLPR3 inflammasome activation, and proinflammatory cytokines (IL-1β and IL-18) release. Surface plasmon resonance (SPR), ELISA, and CH50 assays were used to test the affinity between CP40-KK and rat/human complement C3. CP40-KK group rats only received CP40-KK (2 mg/kg) by subcutaneous injection at day 15 to day 28 continuously.

RESULTS

C3a was significantly upregulated in the plasma of MCT-treated rats. SPR, ELISA, and CH50 assays revealed that CP40-KK displayed similar affinity binding to human and rat complement C3. Pharmacological inhibition of complement C3 cleavage (CP40-KK) could ameliorate MCT-induced NLRP3 inflammasome activity, pulmonary vascular remodeling, and right ventricular hypertrophy. Mechanistically, increased proliferation of pulmonary arterial smooth muscle cells is closely associated with macrophage infiltration, NLPR3 inflammasome activation, and proinflammatory cytokines (IL-1β and IL-18) release. Besides, C3a enhanced IL-1β activity in macrophages and promoted pulmonary arterial smooth muscle cell proliferation in vitro.

CONCLUSION

Our findings suggest that CP40-KK treatment was protective in the MCT-induced rat PAH model, which might serve as a therapeutic option for PAH.

Activation of the alternative complement pathway modulates inflammation in thoracic aortic aneurysm/dissection

Thoracic aortic aneurysm/dissection (TAAD) is a lethal vascular disease, and several pathological factors participate in aortic medial degeneration. We previously discovered that the complement C3a-C3aR axis in smooth muscle cells promotes the development of thoracic aortic dissection (TAD) through regulation of matrix metalloproteinase 2. However, discerning the specific complement pathway that is activated and elucidating how inflammation of the aortic wall is initiated remain unknown. We ascertained that the plasma levels of C3a and C5a were significantly elevated in patients with TAD and that the levels of C3a, C4a, and C5a were higher in acute TAD than in chronic TAD. We also confirmed the activation of the complement in a TAD mouse model. Subsequently, knocking out Cfb (Cfb) or C4 in mice with TAD revealed that the alternative pathway and Cfb played a significant role in the TAD process. Activation of the alternative pathway led to generation of the anaphylatoxins C3a and C5a, and knocking out their receptors reduced the recruitment of inflammatory cells to the aortic wall. Moreover, we used serum from wild-type mice or recombinant mice Cfb as an exogenous source of Cfb to treat Cfb KO mice and observed that it exacerbated the onset and rupture of TAD. Finally, we knocked out Cfb in the FBN1C1041G/+ Marfan-syndrome mice and showed that the occurrence of TAA was reduced. In summary, the alternative complement pathway promoted the development of TAAD by recruiting infiltrating inflammatory cells. Targeting the alternative pathway may thus constitute a strategy for preventing the development of TAAD.NEW & NOTEWORTHY The alternative complement pathway promoted the development of TAAD by recruiting infiltrating inflammatory cells. Targeting the alternative pathway may thus constitute a strategy for preventing the development of TAAD.

The complement cascade in lung injury and disease

BACKGROUND

The complement system is an important arm of immune defense bringing innate and adaptive immunity. Although originally regarded as a major complementary defense mechanism against pathogens, continuously emerging evidence has uncovered a central role of this complex system in several diseases including lung pathologies.

MAIN BODY

Complement factors such as anaphylatoxins C3a and C5a, their receptors C3aR, C5aR and C5aR2 as well as complement inhibitory proteins CD55, CD46 and CD59 have been implicated in pathologies such as the acute respiratory distress syndrome, pneumonia, chronic obstructive pulmonary disease, asthma, interstitial lung diseases, and lung cancer. However, the exact mechanisms by which complement factors induce these diseases remain unclear. Several complement-targeting monoclonal antibodies are reported to treat lung diseases.

CONCLUSIONS

The complement system contributes to the progression of the acute and chronic lung diseases. Better understanding of the underlying mechanisms will provide groundwork to develop new strategy to target complement factors for treatment of lung diseases.

Diagnostic Value of Serum Galectin-3 Binding Protein Level in Patients with Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) still lacks effective biomarkers to assist in its diagnosis and prognosis. Galectin-3 binding protein (Gal-3BP) plays a role in immune and inflammatory diseases.

OBJECTIVE

This study aimed to evaluate Gal-3BP as a prognostic and predictive factor in patients with PAH.

METHODS

From January 2017 to December 2019, we enrolled 167 consecutive PAH patients and 58 healthy controls. Right heart catheterization (RHC) was used to diagnose PAH. Serum Gal-3BP levels were measured by high-sensitivity human enzyme-linked immunosorbent assay (ELISA).

RESULTS

Serum Gal-3BP levels in the PAH group were significantly higher compared with the control group (4.87±2.09 vs 2.22±0.86 μg/mL, p<0.001). Gal-3BP level was correlated with several hemodynamic parameters obtained from RHC (p<0.001). Multivariate linear regression analysis showed that Gal-3BP was a risk factor for PAH (odds ratio (OR)=2.947, 95% CI: 1.821-4.767, p<0.001). The optimal cut-off value of serum Gal-3BP level for predicting PAH was 2.89 μg/mL (area under the curve (AUC)=0.860, 95 % CI: 0.811-0.910, p<0.001). Kaplan-Meier analysis showed that Gal-3BP levels above the median (4.87 μg/mL) were associated with an increased risk of death in patients with PAH (hazard ratio (HR)=8.868, 95 % CI: 3.631-21.65, p<0.0001). Cox multivariate risk regression analysis showed that Gal-3BP was a risk factor for death in PAH patients (HR=2.779, 95 % CI: 1.823-4.237, p<0.001).

CONCLUSION

Serum Gal-3BP levels were increased in patients with PAH, and levels of Gal-3BP were associated with the severity of PAH. Gal-3BP might have predictive value for the diagnosis and prognosis of PAH.

Global and endothelial G-protein coupled receptor 75 (GPR75) knockout relaxes pulmonary artery and mitigates hypoxia-induced pulmonary hypertension

RATIONALE

Pulmonary hypertension (PH) is a multifactorial disease with a poor prognosis and inadequate treatment options. We found two-fold higher expression of the orphan G-Protein Coupled Receptor 75 (GPR75) in leukocytes and pulmonary arterial smooth muscle cells from idiopathic PH patients and from lungs of C57BL/6 mice exposed to hypoxia. We therefore postulated that GPR75 signaling is critical to the pathogenesis of PH.

METHODS

To test this hypothesis, we exposed global (Gpr75-/-) and endothelial cell (EC) GPR75 knockout (EC-Gpr75-/-) mice and wild-type (control) mice to hypoxia (10% oxygen) or normal atmospheric oxygen for 5 weeks. We then recorded echocardiograms and performed right heart catheterizations.

RESULTS

Chronic hypoxia increased right ventricular systolic and diastolic pressures in wild-type mice but not Gpr75-/- or EC-Gpr75-/- mice. In situ hybridization and qPCR results revealed that Gpr75 expression was increased in the alveoli, airways and pulmonary arteries of mice exposed to hypoxia. In addition, levels of chemokine (CC motif) ligand 5 (CCL5), a low affinity ligand of GPR75, were increased in the lungs of wild-type, but not Gpr75-/-, mice exposed to hypoxia, and CCL5 enhanced hypoxia-induced contraction of intra-lobar pulmonary arteries in a GPR75-dependent manner. Gpr75 knockout also increased pulmonary cAMP levels and decreased contraction of intra-lobar pulmonary arteries evoked by endothelin-1 or U46619 in cAMP-protein kinase A-dependent manner.

CONCLUSION

These results suggest GPR75 has a significant role in the development of hypoxia-induced PH.

Uncovering the Neural Correlates of Anhedonia Subtypes in Major Depressive Disorder: Implications for Intervention Strategies

Major depressive disorder (MDD) represents a serious public health concern, negatively affecting individuals' quality of life and making a substantial contribution to the global burden of disease. Anhedonia is a core symptom of MDD and is associated with poor treatment outcomes. Variability in anhedonia components within MDD has been observed, suggesting heterogeneity in psychopathology across subgroups. However, little is known about anhedonia subgroups in MDD and their underlying neural correlates across subgroups. To address this question, we employed a hierarchical cluster analysis based on Temporal Experience of Pleasure Scale subscales in 60 first-episode, drug-naive MDD patients and 32 healthy controls. Then we conducted a connectome-wide association study and whole-brain voxel-wise functional analyses for identified subgroups. There were three main findings: (1) three subgroups with different anhedonia profiles were identified using a data mining approach; (2) several parts of the reward network (especially pallidum and dorsal striatum) were associated with anticipatory and consummatory pleasure; (3) different patterns of within- and between-network connectivity contributed to the disparities of anhedonia profiles across three MDD subgroups. Here, we show that anhedonia in MDD is not uniform and can be categorized into distinct subgroups, and our research contributes to the understanding of neural underpinnings, offering potential treatment directions. This work emphasizes the need for tailored approaches in the complex landscape of MDD. The identification of homogeneous, stable, and neurobiologically valid MDD subtypes could significantly enhance our comprehension and management of this multifaceted condition.

The Role of NCS1 in Immunotherapy and Prognosis of Human Cancer

The Neural Calcium Sensor1 (NCS1) is a crucial protein that binds to Ca2+ and is believed to play a role in regulating tumor invasion and cell proliferation. However, the role of NCS1 in immune infiltration and cancer prognosis is still unknown. Our study aimed to explore the expression profile, immune infiltration pattern, prognostic value, biological function, and potential compounds targeting NCS1 using public databases. High expression of NCS1 was detected by immune histochemical staining in LIHC (Liver hepatocellular carcinoma), BRCA (Breast invasive carcinoma), KIRC (Kidney renal clear cell carcinoma), and SKCM (Skin Cutaneous Melanoma). The expression of NCS1 in cancer was determined by TCGA (The Cancer Genome Atlas Program), GTEx (The Genotype-Tissue Expression), the Kaplan-Meier plotter, GEO (Gene Expression Omnibus), GEPIA2.0 (Gene Expression Profiling Interactive Analysis 2.0), HPA (The Human Protein Atlas), UALCAN, TIMER2.0, TISIDB, Metascape, Drugbank, chEMBL, and ICSDB databases. NCS1 has genomic mutations as well as aberrant DNA methylation in multiple cancers compared to normal tissues. Also, NCS1 was significantly different in the immune microenvironment, tumor mutational burden (TMB), microsatellite instability (MSI), and immune infiltrate-associated cells in different cancers, which could be used for the typing of immune and molecular subtypes of cancer and the presence of immune checkpoint resistance in several cancers. Univariate regression analysis, multivariate regression analysis, and gene enrichment analysis to construct prognostic models revealed that NCS1 is involved in immune regulation and can be used as a prognostic biomarker for SKCM, LIHC, BRCA, COAD, and KIRC. These results provide clues from a bioinformatic perspective and highlight the importance of NCS1 in a variety of cancers.

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.

A Bioinformatic Algorithm based on Pulmonary Endoarterial Biopsy for Targeted Pulmonary Arterial Hypertension Therapy

Background

Optimal pharmacological therapy for pulmonary arterial hypertension (PAH) remains unclear, as pathophysiological heterogeneity may affect therapeutic outcomes. A ranking methodology based on pulmonary vascular genetic expression analysis could assist in medication selection and potentially lead to improved prognosis.

Objective

To describe a bioinformatics approach for ranking currently approved pulmonary arterial antihypertensive agents based on gene expression data derived from percutaneous endoarterial biopsies in an animal model of pulmonary hypertension.

Methods

We created a chronic PAH model in Micro Yucatan female swine by surgical anastomosis of the left pulmonary artery to the descending aorta. A baseline catheterization, angiography and pulmonary endoarterial biopsy were performed. We obtained pulmonary vascular biopsy samples by passing a biopsy catheter through a long 8 French sheath, introduced via the carotid artery, into 2- to 3-mm peripheral pulmonary arteries. Serial procedures were performed on days 7, 21, 60, and 180 after surgical anastomosis. RNA microarray studies were performed on the biopsy samples.

Results

Utilizing the medical literature, we developed a list of PAH therapeutic agents, along with a tabulation of genes affected by these agents. The effect on gene expression from pharmacogenomic interactions was used to rank PAH medications at each time point. The ranking process allowed the identification of a theoretical optimum three-medication regimen.

Conclusion

We describe a new potential paradigm in the therapy for PAH, which would include endoarterial biopsy, molecular analysis and tailored pharmacological therapy for patients with PAH.

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.

A modified primary culture method of rat pulmonary vein smooth muscle cells

BACKGROUND

Although the pressure of pulmonary vein increases before pulmonary artery in pulmonary hypertension due to left heart disease (PH-LHD), only a few studies have assessed pulmonary vein smooth muscle cells (PVSMCs) because of the lack of a simple and feasible isolation method.

METHODS

In this study, we introduced a simple method to obtain PVSMCs. Primary pulmonary veins were removed by puncture needle cannula guidance. Then, PVSMCs were cultured by the tissue explant method and purified by the differential adhesion method. The cells were characterized by hematoxylin-eosin (HE) staining, immunohistochemistry, western blotting, and immunofluorescence to observe the morphology and verify the expression of alpha-smooth muscle actin (α-SMA).

RESULTS

The HE staining results showed that the pulmonary vein media was thinner than the pulmonary artery, the intima and adventitia of the pulmonary vein were removed by this method, and the obtained cells with good activity exhibited morphological characteristics of smooth muscle cells. In addition, higher α-SMA expression was observed in the cells obtained by our isolation method than in the traditional method.

CONCLUSION

This study established a simple and feasible method to isolate and culture PVSMCs that might facilitate the cytological experiments for PH-LHD.

Emerging role of exosomes in vascular diseases

Exosomes are biological small spherical lipid bilayer vesicles secreted by most cells in the body. Their contents include nucleic acids, proteins, and lipids. Exosomes can transfer material molecules between cells and consequently have a variety of biological functions, participating in disease development while exhibiting potential value as biomarkers and therapeutics. Growing evidence suggests that exosomes are vital mediators of vascular remodeling. Endothelial cells (ECs), vascular smooth muscle cells (VSMCs), inflammatory cells, and adventitial fibroblasts (AFs) can communicate through exosomes; such communication is associated with inflammatory responses, cell migration and proliferation, and cell metabolism, leading to changes in vascular function and structure. Essential hypertension (EH), atherosclerosis (AS), and pulmonary arterial hypertension (PAH) are the most common vascular diseases and are associated with significant vascular remodeling. This paper reviews the latest research progress on the involvement of exosomes in vascular remodeling through intercellular information exchange and provides new ideas for understanding related diseases.

Tensions in Taxonomies: Current Understanding and Future Directions in the Pathobiologic Basis and Treatment of Group 1 and Group 3 Pulmonary Hypertension

In the over 100 years since the recognition of pulmonary hypertension (PH), immense progress and significant achievements have been made with regard to understanding the pathophysiology of the disease and its treatment. These advances have been mostly in idiopathic pulmonary arterial hypertension (IPAH), which was classified as Group 1 Pulmonary Hypertension (PH) at the Second World Symposia on PH in 1998. However, the pathobiology of PH due to chronic lung disease, classified as Group 3 PH, remains poorly understood and its treatments thus remain limited. We review the history of the classification of the five groups of PH and aim to provide a state-of-the-art review of the understanding of the pathogenesis of Group 1 PH and Group 3 PH including insights gained from novel high-throughput omics technologies that have revealed heterogeneities within these categories as well as similarities between them. Leveraging the substantial gains made in understanding the genomics, epigenomics, proteomics, and metabolomics of PAH to understand the full spectrum of the complex, heterogeneous disease of PH is needed. Multimodal omics data as well as supervised and unbiased machine learning approaches after careful consideration of the powerful advantages as well as of the limitations and pitfalls of these technologies could lead to earlier diagnosis, more precise risk stratification, better predictions of disease response, new sub-phenotype groupings within types of PH, and identification of shared pathways between PAH and other types of PH that could lead to new treatment targets. © 2023 American Physiological Society. Compr Physiol 13:4295-4319, 2023.

Obstructive sleep apnea-increased DEC1 regulates systemic inflammation and oxidative stress that promotes development of pulmonary arterial hypertension

Obstructive sleep apnea (OSA), characterized by chronic intermittent hypoxia (CIH), is a common risk factor for pulmonary arterial hypertension (PAH). As a hypoxia-induced transcription factor, differentially expressed in chondrocytes (DEC1) negatively regulates the transcription of peroxisome proliferative activated receptor-γ (PPARγ), a recognized protective factor of PAH. However, whether and how DEC1 is associated with PAH pathogenesis remains unclear. In the present study, we found that DEC1 was increased in lungs and pulmonary arterial smooth muscle cells (PASMCs) of rat models of OSA-associated PAH. Oxidative indicators and inflammatory cytokines were also elevated in the blood of the rats. Similarly, hypoxia-treated PASMCs displayed enhanced DEC1 expression and reduced PPARγ expression in vitro. Functionally, DEC1 overexpression exacerbated reactive oxygen species (ROS) production and the expression of pro-inflammatory cytokines (such as TNFα, IL-1β, IL-6, and MCP-1) in PASMCs. Conversely, shRNA knockdown of Dec1 increased PPARγ expression but attenuated hypoxia-induced oxidative stress and inflammatory responses in PASMCs. Additionally, DEC1 overexpression promoted PASMC proliferation, which was drastically attenuated by a PPARγ agonist rosiglitazone. Collectively, these results suggest that hypoxia-induced DEC1 inhibits PPARγ, and that this is a predominant mechanism underpinning oxidative stress and inflammatory responses in PASMCs during PAH. DEC1 could be used as a potential target to treat PAH.

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

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

Potential for TCDD to induce regulatory functions in B cells as part of the mechanism for T cell suppression in EAE

Part of the mechanism by which 2,3,7.8-tetrachlorodibenzo-p-dioxin (TCDD) suppresses immune function involves induction of regulatory T cells and suppression of effector T cells. The goal of this project was to examine whether TCDD's suppression of effector T cells was due in part to inducing B regulatory cells (Bregs). TCDD's potential to increase the percentage and/or function of CD24+CD38+ B cells was assessed in response to lipopolysaccharide (LPS) + interleukin (IL)-4 in vitro and in a mild model of experimental autoimmune encephalomyelitis (EAE) in vivo. In vitro, TCDD did not consistently increase the percentage of CD19+CD24+CD38+ cells using splenocytes, purified B cells or bone marrow (BM) cells. However, TCDD increased IL-10 in all three culture preparations, and TCDD increased the percentage of CD5+CD24+CD38+ cells producing IL-10. In EAE, TCDD did not affect the percentage of the CD24+CD38+ cell population in CD19, B220 or CD5 B cells in splenocytes (SPLC), lymph nodes (LN) nor BM cells at end-stage disease. On the other hand, TCDD increased the CD19+CD24+CD38+ percentage in the spinal cord (SC) in EAE. Moreover, TCDD-treated B cells isolated from spleens or TCDD-treated BM cells in EAE mice modestly reduced the ability of naïve effector T cells to express interferon (IFN)-γ and tumor necrosis factor (TNF)-α. Together these data show that TCDD can induce regulatory functions in B cells, although it was not obvious simply by examining the expression of regulatory markers but by assessing function by cytokine production or mixed lymphocyte responses.

Srolo Bzhtang reduces inflammation and vascular remodeling via suppression of the MAPK/NF-κB signaling pathway in rats with pulmonary arterial hypertension

ETHNOPHARMACOLOGICAL RELEVANCE

Srolo Bzhtang (SBT), which consists of Solms-laubachia eurycarpa, Bergenia purpurascens, Glycyrrhiza uralensis, and lac secreted by Laccifer lacca Kerr (Lacciferidae Cockerell), is a well-known traditional Tibetan medicinal formula and was documented to cure "lung-heat" syndrome by eliminating "chiba" in the ancient Tibetan medical work Four Medical Tantras (Rgyud bzhi). Clinically, it is a therapy for pulmonary inflammatory disorders, such as pneumonia, chronic bronchitis, and chronic obstructive pulmonary disease. However, whether and how SBT participates in pulmonary arterial hypertension (PAH) is still unclear.

AIM OF THE STUDY

We aimed to determine the role of SBT in attenuating pulmonary arterial pressure and vascular remodeling caused by monocrotaline (MCT) and hypoxia. To elucidate the potential mechanism underlying SBT-mediated PAH, we investigated the changes in inflammatory cytokines and mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B (NF-κB) signaling pathway.

MATERIALS AND METHODS

MCT- and hypoxia-induced PAH rat models were used. After administering SBT for four weeks, the rats were tested for hemodynamic indicators, hematological changes, pulmonary arterial morphological changes, and the levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in serum and lung tissues. Protein expression of the MAPK/NF-κB signaling pathway was determined using western blotting.

RESULTS

SBT reduced pulmonary arterial pressure, vascular remodeling, and the levels of inflammatory cytokines induced by MCT and hypoxia in rats. Furthermore, SBT significantly suppressed the MAPK/NF-κB signaling pathway.

CONCLUSIONS

To our knowledge, this is the first study to demonstrate that SBT alleviates MCT- and hypoxia-induced PAH in rats, which is related to its anti-inflammatory actions involving inhibition of the MAPK/NF-κB signaling pathway.

The complement C3-complement factor D-C3a receptor signalling axis regulates cardiac remodelling in right ventricular failure

Failure of the right ventricle plays a critical role in any type of heart failure. However, the mechanism remains unclear, and there is no specific therapy. Here, we show that the right ventricle predominantly expresses alternative complement pathway-related genes, including Cfd and C3aR1. Complement 3 (C3)-knockout attenuates right ventricular dysfunction and fibrosis in a mouse model of right ventricular failure. C3a is produced from C3 by the C3 convertase complex, which includes the essential component complement factor D (Cfd). Cfd-knockout mice also show attenuation of right ventricular failure. Moreover, the plasma concentration of CFD correlates with the severity of right ventricular failure in patients with chronic right ventricular failure. A C3a receptor (C3aR) antagonist dramatically improves right ventricular dysfunction in mice. In summary, we demonstrate the crucial role of the C3-Cfd-C3aR axis in right ventricular failure and highlight potential therapeutic targets for right ventricular failure.

Right ventricular (RV) failure is clinically crucial, but there is no specific therapy. Here, the authors show that the complement alternative pathway is activated in RV failure and that blockade of the pathway ameliorates RV failure in mice.

Inhibition of immunoglobulin E attenuates pulmonary hypertension

Pulmonary hypertension (PH) is a severe cardiopulmonary disease characterized by pulmonary vascular remodeling. Immunoglobulin E (IgE) is known to participate in aortic vascular remodeling, but whether IgE mediates pulmonary vascular disease is unknown. In the present study, we found serum IgE elevation in pulmonary arterial hypertension (PAH) patients, hypoxia-induced PH mice and monocrotaline-induced PH rats. Neutralizing IgE with an anti-IgE antibody was effective in preventing PH development in mice and rat models. The IgE receptor FcεRIα was also upregulated in PH lung tissues and Fcer1a deficiency prevented the development of PH. Single-cell RNA-sequencing revealed that FcεRIα was mostly expressed in mast cells (MCs) and MC-specific Fcer1a knockout protected against PH in mice. IgE-activated MCs produced interleukin (IL)-6 and IL-13, which subsequently promoted vascular muscularization. Clinically approved IgE antibody omalizumab alleviated the progression of established PH in rats. Using genetic and pharmacological approaches, we have demonstrated that blocking IgE-FcεRIα signaling may hold potential for PAH treatment.

Harnessing Big Data to Advance Treatment and Understanding of Pulmonary Hypertension

Pulmonary hypertension is a complex disease with multiple causes, corresponding to phenotypic heterogeneity and variable therapeutic responses. Advancing understanding of pulmonary hypertension pathogenesis is likely to hinge on integrated methods that leverage data from health records, imaging, novel molecular -omics profiling, and other modalities. In this review, we summarize key data sets generated thus far in the field and describe analytical methods that hold promise for deciphering the molecular mechanisms that underpin pulmonary vascular remodeling, including machine learning, network medicine, and functional genetics. We also detail how genetic and subphenotyping approaches enable earlier diagnosis, refined prognostication, and optimized treatment prediction. We propose strategies that identify functionally important molecular pathways, bolstered by findings across multi-omics platforms, which are well-positioned to individualize drug therapy selection and advance precision medicine in this highly morbid disease.

Experimental animal models of pulmonary hypertension: Development and challenges

Pulmonary hypertension (PH) is clinically divided into 5 major types, characterized by elevation in pulmonary arterial pressure (PAP) and pulmonary vascular resistance (PVR), finally leading to right heart failure and death. The pathogenesis of this arteriopathy remains unclear, leaving it impossible to target pulmonary vascular remodeling and reverse the deterioration of right ventricular (RV) function. Different animal models have been designed to reflect the complex mechanistic origins and pathology of PH, roughly divided into 4 categories according to the modeling methods: non‐invasive models in vivo, invasive models in vivo, gene editing models, and multi‐means joint modeling. Though each model shares some molecular and pathological changes with different classes of human PH, in most cases the molecular etiology of human PH is poorly known. The appropriate use of classic and novel PH animal models is essential for the hunt of molecular targets to reverse severe phenotypes.

Dysregulated Immunity in Pulmonary Hypertension: From Companion to Composer

Pulmonary hypertension (PH) represents a grave condition associated with high morbidity and mortality, emphasizing a desperate need for innovative and targeted therapeutic strategies. Cumulative evidence suggests that inflammation and dysregulated immunity interdependently affect maladaptive organ perfusion and congestion as hemodynamic hallmarks of the pathophysiology of PH. The role of altered cellular and humoral immunity in PH gains increasing attention, especially in pulmonary arterial hypertension (PAH), revealing novel mechanistic insights into the underlying immunopathology. Whether these immunophysiological aspects display a universal character and also hold true for other types of PH (e.g., PH associated with left heart disease, PH-LHD), or whether there are unique immunological signatures depending on the underlying cause of disease are points of consideration and discussion. Inflammatory mediators and cellular immune circuits connect the local inflammatory landscape in the lung and heart through inter-organ communication, involving, e.g., the complement system, sphingosine-1-phosphate (S1P), cytokines and subsets of, e.g., monocytes, macrophages, natural killer (NK) cells, dendritic cells (DCs), and T- and B-lymphocytes with distinct and organ-specific pro- and anti-inflammatory functions in homeostasis and disease. Perivascular macrophage expansion and monocyte recruitment have been proposed as key pathogenic drivers of vascular remodeling, the principal pathological mechanism in PAH, pinpointing toward future directions of anti-inflammatory therapeutic strategies. Moreover, different B- and T-effector cells as well as DCs may play an important role in the pathophysiology of PH as an imbalance of T-helper-17-cells (T_H17) activated by monocyte-derived DCs, a potentially protective role of regulatory T-cells (T_reg) and autoantibody-producing plasma cells occur in diverse PH animal models and human PH. This article highlights novel aspects of the innate and adaptive immunity and their interaction as disease mediators of PH and its specific subtypes, noticeable inflammatory mediators and summarizes therapeutic targets and strategies arising thereby.

Bioactivities and mechanisms of natural medicines in the management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and rare disease without obvious clinical symptoms that shares characteristics with pulmonary vascular remodeling. Right heart failure in the terminal phase of PAH seriously threatens the lives of patients. This review attempts to comprehensively outline the current state of knowledge on PAH its pathology, pathogenesis, natural medicines therapy, mechanisms and clinical studies to provide potential treatment strategies. Although PAH and pulmonary hypertension have similar pathological features, PAH exhibits significantly elevated pulmonary vascular resistance caused by vascular stenosis and occlusion. Currently, the pathogenesis of PAH is thought to involve multiple factors, primarily including genetic/epigenetic factors, vascular cellular dysregulation, metabolic dysfunction, even inflammation and immunization. Yet many issues regarding PAH need to be clarified, such as the "oestrogen paradox". About 25 kinds monomers derived from natural medicine have been verified to protect against to PAH via modulating BMPR2/Smad, HIF-1α, PI3K/Akt/mTOR and eNOS/NO/cGMP signalling pathways. Yet limited and single PAH animal models may not corroborate the efficacy of natural medicines, and those natural compounds how to regulate crucial genes, proteins and even microRNA and lncRNA still need to put great attention. Additionally, pharmacokinetic studies and safety evaluation of natural medicines for the treatment of PAH should be undertaken in future studies. Meanwhile, methods for validating the efficacy of natural drugs in multiple PAH animal models and precise clinical design are also urgently needed to promote advances in PAH.

Use of latent profile analysis and k-means clustering to identify student anxiety profiles

BACKGROUND

Anxiety disorders are often the first presentation of psychopathology in youth and are considered the most common psychiatric disorders in children and adolescents. This study aimed to identify distinct student anxiety profiles to develop targeted interventions.

METHODS

A cross-sectional study was conducted with 9738 students in Yingshan County. Background characteristics were collected and Mental Health Test (MHT) were completed. Latent profile analysis (LPA) was applied to define student anxiety profiles, and then the analysis was repeated using k-means clustering.

RESULTS

LPA yielded 3 profiles: the low-risk, mild-risk and high-risk groups, which comprised 29.5, 38.1 and 32.4% of the sample, respectively. Repeating the analysis using k-means clustering resulted in similar groupings. Most students in a particular k-means cluster were primarily in a single LPA-derived student profile. The multinomial ordinal logistic regression results showed that the high-risk group was more likely to be female, junior, and introverted, to live in a town, to have lower or average academic performance, to have heavy or average academic pressure, and to be in schools that have never or occasionally have organized mental health education activities.

CONCLUSIONS

The findings suggest that students with anxiety symptoms may be categorized into distinct profiles that are amenable to varying strategies for coordinated interventions.

Biological heterogeneity in idiopathic pulmonary arterial hypertension identified through unsupervised transcriptomic profiling of whole blood

Idiopathic pulmonary arterial hypertension (IPAH) is a rare but fatal disease diagnosed by right heart catheterisation and the exclusion of other forms of pulmonary arterial hypertension, producing a heterogeneous population with varied treatment response. Here we show unsupervised machine learning identification of three major patient subgroups that account for 92% of the cohort, each with unique whole blood transcriptomic and clinical feature signatures. These subgroups are associated with poor, moderate, and good prognosis. The poor prognosis subgroup is associated with upregulation of the ALAS2 and downregulation of several immunoglobulin genes, while the good prognosis subgroup is defined by upregulation of the bone morphogenetic protein signalling regulator NOG, and the C/C variant of HLA-DPA1/DPB1 (independently associated with survival). These findings independently validated provide evidence for the existence of 3 major subgroups (endophenotypes) within the IPAH classification, could improve risk stratification and provide molecular insights into the pathogenesis of IPAH.

Complement-containing small extracellular vesicles from adventitial fibroblasts induce proinflammatory and metabolic reprogramming in macrophages

Pulmonary hypertension (PH) is a severe cardiopulmonary disease characterized by complement-dependent, fibroblast-induced perivascular accumulation and proinflammatory activation of macrophages. We hypothesized that, in PH, nanoscale-sized small extracellular vesicles (sEVs), released by perivascular/adventitial fibroblasts, are critical mediators of complement-dependent proinflammatory activation of macrophages. Pulmonary adventitial fibroblasts were isolated from calves with severe PH (PH-Fibs) and age-matched controls (CO-Fibs). PH-Fibs exhibited increased secretion of sEVs, compared with CO-Fibs, and sEV biological activity was tested on mouse and bovine bone marrow-derived macrophages (BMDMs) and showed similar responses. Compared with sEVs derived from CO-Fibs, sEVs derived from PH-Fibs (PH-Fib-sEVs) induced augmented expression of proinflammatory cytokines/chemokines and metabolic genes in BMDMs. Pharmacological blockade of exosome release from PH-Fibs resulted in significant attenuation of proinflammatory activation of BMDMs. "Bottom-up" proteomic analyses revealed significant enrichment of complement and coagulation cascades in PH-Fib-sEVs, including augmented expression of the complement component C3. We therefore examined whether the PH-Fib-sEV-mediated proinflammatory activation of BMDMs was complement C3 dependent. Treatment of PH-Fibs with siC3-RNA significantly attenuated the capacity of PH-Fib-sEVs for proinflammatory activation of BMDMs. PH-Fib-sEVs mediated proglycolytic alterations and complement-dependent activation of macrophages toward a proinflammatory phenotype, as confirmed by metabolomic studies. Thus, fibroblast-released sEVs served as critical mediators of complement-induced perivascular/microenvironmental inflammation in PH.