Abnormal pulmonary endothelial cells may underlie the enigmatic pathogenesis of chronic thromboembolic pulmonary hypertension

CC chemokines Modulate Immune responses in Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension (PH) represents a progressive condition characterized by the remodeling of pulmonary arteries, ultimately culminating in right heart failure and increased mortality rates. Substantial evidence has elucidated the pivotal role of perivascular inflammatory factors and immune dysregulation in the pathogenesis of PH. Chemokines, a class of small secreted proteins, exert precise control over immune cell recruitment and functionality, particularly with respect to their migration to sites of inflammation. Consequently, chemokines emerge as critical drivers facilitating immune cell infiltration into the pulmonary tissue during inflammatory responses. This review comprehensively examines the significant contributions of CC chemokines in the maintenance of immune cell homeostasis and their pivotal role in regulating inflammatory responses. The central focus of this discussion is directed towards elucidating the precise immunoregulatory actions of CC chemokines concerning various immune cell types, including neutrophils, monocytes, macrophages, lymphocytes, dendritic cells, mast cells, eosinophils, and basophils, particularly in the context of pH processes. Furthermore, this paper delves into an exploration of the underlying pathogenic mechanisms that underpin the development of PH. Specifically, it investigates processes such as cellular pyroptosis, examines the intricate crosstalk between bone morphogenetic protein receptor type 2 (BMPR2) mutations and the immune response, and sheds light on key signaling pathways involved in the inflammatory response. These aspects are deemed critical in enhancing our understanding of the complex pathophysiology of PH. Moreover, this review provides a comprehensive synthesis of findings from experimental investigations targeting immune cells and CC chemokines.

AIM OF REVIEW

In summary, the inquiry into the inflammatory responses mediated by CC chemokines and their corresponding receptors, and their potential in modulating immune reactions, holds promise as a prospective avenue for addressing PH. The potential inhibition of CC chemokines and their receptors stands as a viable strategy to attenuate the inflammatory cascade and ameliorate the pathological manifestations of PH. Nonetheless, it is essential to acknowledge the current state of clinical trials and the ensuing progress, which regrettably appears to be less than encouraging. Substantial hurdles exist in the successful translation of research findings into clinical applications. The intention is that such emphasis could potentially foster the advancement of potent therapeutic agents presently in the process of clinical evaluation. This, in turn, may further bolster the potential for effective management of PH.

Chronic thromboembolic pulmonary hypertension and balloon pulmonary angioplasty - Where are we in 2024?

Pulmonary endarterectomy (PEA) is the first-line treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, some patients with CTEPH are considered inoperable, and in the last decade, balloon pulmonary angioplasty (BPA) has emerged as a viable therapeutic option for these patients with prohibitive surgical risk or recurrent pulmonary hypertension following PEA. Numerous international centers have increased their procedural volume of BPA and have reported improvements in pulmonary hemodynamics, patient functional class and right ventricular function. Randomized controlled trials have also demonstrated similar findings. Recent refinements in procedural technique, increased operator experience and advancements in procedural technology have facilitated marked reduction in the risk of complications following BPA. Current guidelines recommend BPA for patients with inoperable CTEPH and persistent pulmonary hypertension following PEA. The pulmonary arterial endothelium plays a vital role in the pathophysiologic development and progression of CTEPH.

Analysis of genes characterizing chronic thrombosis and associated pathways in chronic thromboembolic pulmonary hypertension

PURPOSE

In chronic thromboembolic pulmonary hypertension (CTEPH), fibrosis of thrombi in the lumen of blood vessels and obstruction of blood vessels are important factors in the progression of the disease. Therefore, it is important to explore the key genes that lead to chronic thrombosis in order to understand the development of CTEPH, and at the same time, it is beneficial to provide new directions for early identification, disease prevention, clinical diagnosis and treatment, and development of novel therapeutic agents.

METHODS

The GSE130391 dataset was downloaded from the Gene Expression Omnibus (GEO) public database, which includes the full gene expression profiles of patients with CTEPH and Idiopathic Pulmonary Arterial Hypertension (IPAH). Differentially Expressed Genes (DEGs) of CTEPH and IPAH were screened, and then Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) functional enrichment analyses were performed on the DEGs; Weighted Gene Co-Expression Network Analysis (WGCNA) to screen the key gene modules and take the intersection genes of DEGs and the key module genes in WGCNA; STRING database was used to construct the protein-protein interaction (PPI) network; and cytoHubba analysis was performed to identify the hub genes.

RESULTS

A total of 924 DEGs were screened, and the MEturquoise module with the strongest correlation was selected to take the intersection with DEGs A total of 757 intersecting genes were screened. The top ten hub genes were analyzed by cytoHubba: IL-1B, CXCL8, CCL22, CCL5, CCL20, TNF, IL-12B, JUN, EP300, and CCL4.

CONCLUSION

IL-1B, CXCL8, CCL22, CCL5, CCL20, TNF, IL-12B, JUN, EP300, and CCL4 have diagnostic and therapeutic value in CTEPH disease, especially playing a role in chronic thrombosis. The discovery of NF-κB, AP-1 transcription factors, and TNF signaling pathway through pivotal genes may be involved in the disease progression process.

Chronic Thromboembolic Pulmonary Hypertension: A Review of the Multifaceted Pathobiology

Chronic thromboembolic pulmonary disease results from the incomplete resolution of thrombi, leading to fibrotic obstructions. These vascular obstructions and additional microvasculopathy may lead to chronic thromboembolic pulmonary hypertension (CTEPH) with increased pulmonary arterial pressure and pulmonary vascular resistance, which, if left untreated, can lead to right heart failure and death. The pathobiology of CTEPH has been challenging to unravel due to its rarity, possible interference of results with anticoagulation, difficulty in selecting the most relevant study time point in relation to presentation with acute pulmonary embolism (PE), and lack of animal models. In this article, we review the most relevant multifaceted cross-talking pathogenic mechanisms and advances in understanding the pathobiology in CTEPH, as well as its challenges and future direction. There appears to be a genetic background affecting the relevant pathological pathways. This includes genetic associations with dysfibrinogenemia resulting in fibrinolysis resistance, defective angiogenesis affecting thrombus resolution, and inflammatory mediators driving chronic inflammation in CTEPH. However, these are not necessarily specific to CTEPH and some of the pathways are also described in acute PE or deep vein thrombosis. In addition, there is a complex interplay between angiogenic and inflammatory mediators driving thrombus non-resolution, endothelial dysfunction, and vascular remodeling. Furthermore, there are data to suggest that infection, the microbiome, circulating microparticles, and the plasma metabolome are contributing to the pathobiology of CTEPH.

Pathogenesis, Diagnosis, and Management of Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is thought to occur as a sequelae of thromboembolic processes in the pulmonary vasculature. The pathophysiology of CTEPH is multifactorial, including impaired fibrinolysis, endothelial dysregulation, and hypoxic adaptations. The diagnosis of CTEPH is typically delayed considering the nonspecific nature of the symptoms, lack of screening, and relatively low incidence. Diagnostic tools include ventilation-perfusion testing, echocardiography, cardiac catheterization, and pulmonary angiography. The only potentially curative treatment for CTEPH is pulmonary endarterectomy However, approximately 40% of patients are inoperable. Currently, only Riociguat is Food and Drug Administration approved specifically for CTEPH, with additional drug trials underway.

PVECs-Derived Exosomal microRNAs Regulate PASMCs via FoxM1 Signaling in IUGR-induced Pulmonary Hypertension

Background Intrauterine growth restriction (IUGR) is closely related to systemic or pulmonary hypertension (PH) in adulthood. Aberrant crosstalk between pulmonary vascular endothelial cells (PVECs) and pulmonary arterial smooth muscle cells (PASMCs) that is mediated by exosomes plays an essential role in the progression of PH. FoxM1 (Forkhead box M1) is a key transcription factor that governs many important biological processes. Methods and Results IUGR-induced PH rat models were established. Transwell plates were used to coculture PVECs and PASMCs. Exosomes were isolated from PVEC-derived medium, and a microRNA (miRNA) screening was proceeded to identify effects of IUGR on small RNAs enclosed within exosomes. Dual-Luciferase assay was performed to validate the predicted binding sites of miRNAs on FoxM1 3' untranslated region. FoxM1 inhibitor thiostrepton was used in IUGR-induced PH rats. In this study, we found that FoxM1 expression was remarkably increased in IUGR-induced PH, and PASMCs were regulated by PVECs through FoxM1 signaling in a non-contact way. An miRNA screening showed that miR-214-3p, miR-326-3p, and miR-125b-2-3p were downregulated in PVEC-derived exosomes of the IUGR group, which were associated with overexpression of FoxM1 and more significant proliferation and migration of PASMCs. Dual-Luciferase assay demonstrated that the 3 miRNAs directly targeted FoxM1 3' untranslated region. FoxM1 inhibition blocked the PVECs-PASMCs crosstalk and reversed the abnormal functions of PASMCs. In vivo, treatment with thiostrepton significantly reduced the severity of PH. Conclusions Transmission of exosomal miRNAs from PVECs regulated the functions of PASMCs via FoxM1 signaling, and FoxM1 may serve as a potential therapeutic target in IUGR-induced PH.

LncRNA GAS5 promotes spermidine‑induced autophagy through the miRNA‑31‑5p/NAT8L axis in pulmonary artery endothelial cells of patients with CTEPH

Chronic thromboembolic pulmonary hypertension (CTEPH) is a leading cause of pulmonary hypertension. The present study investigated the mechanisms of long non-coding RNA growth arrest-specific transcript 5 (GAS5) on spermidine (SP)-induced autophagy. Pulmonary artery endothelial cells (PAECs) were collected from patients with CTEPH and the rat model. Immunofluorescence, Western blots, reverse transcription-quantitative polymerase chain reaction, bioinformatics, rapid amplification of cDNA ends assays, luciferase reporter assays, RNA-binding protein immunoprecipitation assays, GFP-LC3 adenoviruses, tfLC3 assays and transmission electron microscopy were performed. The results revealed that SP-induced autophagy increased GAS5 in PAECs. The upregulation of GAS5 enhanced and the downregulation of GAS5 reversed the roles of SP in PAECs. Furthermore, GAS5 promoted SP-induced autophagy in PAECs by targeting miRNA-31-5p. The miRNA-31-5p mimic suppressed and the inhibitor promoted SP-induced autophagy. Furthermore, N-Acetyltransferase 8 Like (NAT8L) was a target gene of miRNA-31-5p and knockdown of NAT8L inhibited the autophagic levels of PAECs. In vivo, SP treatment decreased miRNA-31-5p and increased NAT8L levels, which was reversed by the knockdown of GAS5. The downregulation of GAS5 abolished the stimulatory role of SP in PAECs of CTEPH rats. In conclusion, GAS5 promoted SP-induced autophagy through miRNA-31-5p/NAT8L signaling pathways in vitro and in vivo and GAS5 may be a promising molecular marker for therapies of CTEPH.

Cytokine Storm Signature in Patients with Moderate and Severe COVID-19

Hypercytokinemia, found in SARS-CoV-2 infection, contributes to multiple organ dysfunctions with acute respiratory distress syndrome, shock etc. The aim of this study was to describe cytokine storm signatures in patients with acute COVID-19 and to investigate their influence on severity of the infection. Plasma levels of 47 cytokines were investigated in 73 patients with moderate and severe COVID-19 (41 and 32, respectively) and 11 healthy donors (HD). The most elevated levels comparing patients and the HD were observed for seven pro-inflammatory cytokines (IL-6, IL-8, IL-15, IL-18, IL-27, IFNγ, TNFα), three chemokines (GROα, IP-10, MIG), two anti-inflammatory cytokines (IL-1RA, IL-10), and two growth factors (G-CSF, M-CSF). The patients with severe disease had significantly higher levels of FGF-2/FGF-basic, IL-1β, and IL-7 compared to the HD. The two groups of patients differed from each other only based on the levels of EGF, eotaxin, and IL-12 p40. Pneumonia lung injury, characterized by computer tomography, positively correlated with levels of EGF, IP-10, MCP-3 levels and negatively with IL-12 p40. Pro-inflammatory factors including IL-6, TNFα, and IP-10 negatively correlated with the frequency of the circulating T-helper17-like cells (Th17-like) and follicular Th cells that are crucial to develop SARS-CoV-2-specific plasma cells and memory B cells. Obtained data on the cytokine levels illustrate their influence on progression and severity of COVID-19.

Hypoxic pulmonary endothelial cells release epidermal growth factor leading to vascular smooth muscle cell arginase-2 expression and proliferation

The hallmark of pulmonary hypertension (PH) is vascular remodeling. We have previously shown that human pulmonary microvascular endothelial cells (hPMVEC) respond to hypoxia with epidermal growth factor (EGF) mediated activation of the receptor tyrosine kinase, EGF receptor (EGFR), resulting in arginase-2 (Arg2)-dependent proliferation. We hypothesized that the release of EGF by hPMVEC could result in the proliferation of human pulmonary arterial smooth muscle cells (hPASMC) via activation of EGFR on the hPASMC leading to Arg2 up-regulation. To test this hypothesis, we used conditioned media (CM) from hPMVEC grown either in normoxia (NCM) or hypoxia (HCM). Human PASMC were incubated in normoxia with either HCM or NCM, and HCM caused significant induction of Arg2 and viable cell numbers. When HCM was generated with either an EGF-neutralizing antibody or an EGFR blocking antibody the resulting HCM did not induce Arg2 or increase viable cell numbers in hPASMC. Adding an EGFR blocking antibody to HCM, prevented the HCM-induced increase in Arg2 and viable cell numbers. HCM induced robust phosphorylation of hPASMC EGFR. When hPASMC were transfected with siRNA against EGFR the HCM-induced increase in viable cell numbers was prevented. When hPASMC were treated with the arginase antagonist nor-NOHA, the HCM-induced increase in viable cell numbers was prevented. These data suggest that hypoxic hPMVEC releases EGF, which activates hPASMC EGFR leading to Arg2 protein expression and an increase in viable cell numbers. We speculate that EGF neutralizing antibodies or EGFR blocking antibodies represent potential therapeutics to prevent and/or attenuate vascular remodeling in PH associated with hypoxia.

Metabolic profile in endothelial cells of chronic thromboembolic pulmonary hypertension and pulmonary arterial hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH) are two forms of pulmonary hypertension (PH) characterized by obstructive vasculopathy. Endothelial dysfunction along with metabolic changes towards increased glycolysis are important in PAH pathophysiology. Less is known about such abnormalities in endothelial cells (ECs) from CTEPH patients. This study provides a systematic metabolic comparison of ECs derived from CTEPH and PAH patients. Metabolic gene expression was studied using qPCR in cultured CTEPH-EC and PAH-EC. Western blot analyses were done for HK2, LDHA, PDHA1, PDK and G6PD. Basal viability of CTEPH-EC and PAH-EC with the incubation with metabolic inhibitors was measured using colorimetric viability assays. Human pulmonary artery endothelial cells (HPAEC) were used as healthy controls. Whereas PAH-EC showed significant higher mRNA levels of GLUT1, HK2, LDHA, PDHA1 and GLUD1 metabolic enzymes compared to HPAEC, CTEPH-EC did not. Oxidative phosphorylation associated proteins had an increased expression in PAH-EC compared to CTEPH-EC and HPAEC. PAH-EC, CTEPH-EC and HPAEC presented similar HOXD macrovascular gene expression. Metabolic inhibitors showed a dose-dependent reduction in viability in all three groups, predominantly in PAH-EC. A different metabolic profile is present in CTEPH-EC compared to PAH-EC and suggests differences in molecular mechanisms important in the disease pathology and treatment.

The Roles of S100A4 and the EGF/EGFR Signaling Axis in Pulmonary Hypertension with Right Ventricular Hypertrophy

Pulmonary hypertension (PH) is characterized by increased pulmonary arterial pressure caused by the accumulation of mesenchymal-like cells in the pulmonary vasculature. PH can lead to right ventricular hypertrophy (RVH) and, ultimately, heart failure and death. In PH etiology, endothelial-to-mesenchymal transition (EndMT) has emerged as a critical process governing the conversion of endothelial cells into mesenchymal cells, and S100A4, EGF, and EGFR are implicated in EndMT. However, a potential role of S100A4, EGF, and EGFR in PH has to date not been elucidated. We therefore quantified S100A4, EGF, and EGFR in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH) and idiopathic pulmonary arterial hypertension (iPAH). To determine specificity for unilateral heart disease, the EndMT biomarker signature was further compared between PH patients presenting with RVH and patients suffering from aortic valve stenosis (AVS) with left ventricular hypertrophy. Reduced S100A4 concentrations were found in CTEPH and iPAH patients with RVH. Systemic EGF was increased in CTEPH but not in iPAH, while AVS patients displayed slightly diminished EGF levels. EGFR was downregulated in all patient groups when compared to healthy controls. Longitudinal data analysis revealed no effect of surgical therapies on EndMT markers. Pulmonary thrombo-endarterectomized samples were devoid of S100A4, while S100A4 tissue expression positively correlated with higher grades of Heath–Edwards histopathological lesions of iPAH-derived lung tissue. Histologically, EGFR was not detectable in CTEPH lungs or in iPAH lesions. Together, our data suggest an intricate role for S100A4 and EGF/EGFR in PH with right heart pathology.

Resveratrol attenuates chronic pulmonary embolism-related endothelial cell injury by modulating oxidative stress, inflammation, and autophagy

OBJECTIVES

Due to Pulmonary Artery Endothelial Cell (PAEC) dysfunction, Pulmonary Hypertension (PH) persists even after the Pulmonary Embolism (PE) has been relieved. However, the mechanism behind this remains unclear.

METHOD

Here, the authors incubated Human PAECs (HPAECs) with thrombin to simulate the process of arterial thrombosis.

RESULTS

CCK8 results showed a decrease in the viability of HPAECs after thrombin incubation. In addition, the expression of Tissue Factor (TF), Monocyte Chemoattractant Protein 1 (MCP-1), VCAM-1, ICAM-1, cleaved caspase 3, cleaved caspase 9, and Bax protein were all increased after thrombin incubation, while Bcl-2 was decreased. The effects of 3-MA treatment further suggested that autophagy might mediate the partial protective effects of Resveratrol on HPAECs. To observe the effects of Resveratrol in vivo, the authors established a Chronic Thromboembolic Pulmonary Hypertension (CTEPH) model by repeatedly injecting autologous blood clots into a rat's left jugular vein. The results exhibited that Mean Pulmonary Arterial Pressure (mPAP) and vessel Wall Area/Total Area (WA/TA) ratio were both decreased after Resveratrol treatment. Moreover, Resveratrol could reduce the concentration and activity of TF, vWF, P-selectin, and promote these Superoxide Dismutase (SOD) in plasma. Western blot analysis of inflammation, platelet activation, autophagy, and apoptosis-associated proteins in pulmonary artery tissue validated the results in PHAECs.

CONCLUSIONS

These findings suggested that reduced autophagy, increased oxidative stress, increased platelet activation, and increased inflammation were involved in CTEPH-induced HPAEC dysfunction and the development of PH, while Resveratrol could improve PAEC dysfunction and PH.

Examining the Development of Chronic Thromboembolic Pulmonary Hypertension at the Single-Cell Level

BACKGROUND

The mechanism of chronic thromboembolic pulmonary hypertension (CTEPH) is known to be multifactorial but remains incompletely understood.

METHODS

In this study, single-cell RNA sequencing, which facilitates the identification of molecular profiles of samples on an individual cell level, was applied to investigate individual cell types in pulmonary endarterectomized tissues from 5 patients with CTEPH. The order of single-cell types was then traced along the developmental trajectory of CTEPH by trajectory inference analysis, and intercellular communication was characterized by analysis of ligand-receptor pairs between cell types. Finally, comprehensive bioinformatics tools were used to analyze possible functions of branch-specific cell types and the underlying mechanisms.

RESULTS

Eleven cell types were identified, with immune-related cell types (T cells, natural killer cells, macrophages, and mast cells) distributed in the left (early) branch of the pseudotime tree, cancer stem cells, and CRISPLD2+ cells as intermediate cell types, and classic disease-related cell types (fibroblasts, smooth muscle cells, myofibroblasts, and endothelial cells) in the right (later) branch. Ligand-receptor interactions revealed close communication between macrophages and disease-related cell types as well as between smooth muscle cells and fibroblasts or endothelial cells. Moreover, the ligands and receptors were significantly enriched in key pathways such as the PI3K/Akt signaling pathway. Furthermore, highly expressed genes specific to the undefined cell type were significantly enriched in important functions associated with regulation of endoplasmic reticulum stress.

CONCLUSIONS

This single-cell RNA sequencing analysis revealed the order of single cells along a developmental trajectory in CTEPH as well as close communication between different cell types in CTEPH pathogenesis.

Derivation and characterisation of endothelial cells from patients with chronic thromboembolic pulmonary hypertension

Pulmonary endarterectomy (PEA) resected material offers a unique opportunity to develop an in vitro endothelial cell model of chronic thromboembolic pulmonary hypertension (CTEPH). We aimed to comprehensively analyze the endothelial function, molecular signature, and mitochondrial profile of CTEPH-derived endothelial cells to better understand the pathophysiological mechanisms of endothelial dysfunction behind CTEPH, and to identify potential novel targets for the prevention and treatment of the disease. Isolated cells from specimens obtained at PEA (CTEPH-EC), were characterized based on morphology, phenotype, and functional analyses (in vitro and in vivo tubule formation, proliferation, apoptosis, and migration). Mitochondrial content, morphology, and dynamics, as well as high-resolution respirometry and oxidative stress, were also studied. CTEPH-EC displayed a hyperproliferative phenotype with an increase expression of adhesion molecules and a decreased apoptosis, eNOS activity, migration capacity and reduced angiogenic capacity in vitro and in vivo compared to healthy endothelial cells. CTEPH-EC presented altered mitochondrial dynamics, increased mitochondrial respiration and an unbalanced production of reactive oxygen species and antioxidants. Our study is the foremost comprehensive investigation of CTEPH-EC. Modulation of redox, mitochondrial homeostasis and adhesion molecule overexpression arise as novel targets and biomarkers in CTEPH.

Interactions Between Specific Immune Status of Pregnant Women and SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen responsible for the Coronavirus Disease 2019 (COVID-19) global pandemic. Because it is a new and highly contagious coronavirus, most people, especially pregnant women, lack immunity. It is therefore important to understand the interaction between why pregnant women are susceptible to SARS-CoV-2 and the specific immune systems of pregnant women. Here, we provide an overview of the changes that occur in the immune system during pregnancy, the activation and response of the immune system in pregnant women with COVID-19, adverse pregnancy outcomes in pregnant women with COVID-19, and the treatment and prevention of COVID-19 in this population.

In situ Pulmonary Artery Thrombosis: A Previously Overlooked Disease

Pulmonary thromboembolism (PTE) is the third leading cause of death in cardiovascular diseases. PTE is believed to be caused by thrombi detached from deep veins of lower extremities. The thrombi travel with systemic circulation to the lung and block pulmonary arteries, leading to sudden disruption of hemodynamics and blood gas exchange. However, this concept has recently been challenged by accumulating evidence demonstrating that de novo thrombosis may be formed in pulmonary arteries without deep venous thrombosis. On the other hand, chronic thromboembolic pulmonary hypertension (CTEPH), a subtype of pulmonary hypertension, could have different pathogenesis than traditional PTE. Therefore, this article summarized and compared the risk factors, the common and specific pathogenic mechanisms underlying PTE, in situ pulmonary artery thrombosis, and CTEPH at molecular and cellular levels, and suggested the therapeutic strategies to these diseases, aiming to facilitate understanding of pathogenesis, differential diagnosis, and precision therapeutics of the three pulmonary artery thrombotic diseases.

Cell landscape atlas for patients with chronic thromboembolic pulmonary hypertension after pulmonary endarterectomy constructed using single-cell RNA sequencing

This study aimed to construct an atlas of the cell landscape and comprehensively characterize the cellular repertoire of the pulmonary endarterectomized tissues of patients with chronic thromboembolic pulmonary hypertension (CTEPH). Five pulmonary endarterectomized tissues were collected. 10× Genomics single-cell RNA sequencing was performed, followed by the identification of cluster marker genes and cell types. Gene Ontology (GO) enrichment analysis was conducted. Seventeen cell clusters were characterized, corresponding to 10,518 marker genes, and then classified into eight cell types, including fibroblast/smooth muscle cell, endothelial cell, T cell/NK cell, macrophage, mast cell, cysteine rich secretory protein LCCL domain containing 2 (CRISPLD2)+ cell, cancer stem cell, and undefined. The specific marker genes of fibroblast/smooth muscle cell, endothelial cell, T cell/NK cell, macrophage, mast cell, and cancer stem cell were significantly enriched for multiple functions associated with muscle cell migration, endothelial cell migration, T cell activation, neutrophil activation, erythrocyte homeostasis, and tissue remodeling, respectively. No functions were significantly enriched for the marker gene of CRISPLD2+ cell. Our study, for the first time, provides an atlas of the cell landscape of the pulmonary endarterectomized tissues of CTEPH patients at single-cell resolution, which may serve as a valuable resource for further elucidation of disease pathophysiology.

NEDD9 Is a Novel and Modifiable Mediator of Platelet-Endothelial Adhesion in the Pulmonary Circulation

Rationale: Data on the molecular mechanisms that regulate platelet-pulmonary endothelial adhesion under conditions of hypoxia are lacking, but may have important therapeutic implications. Objectives: To identify a hypoxia-sensitive, modifiable mediator of platelet-pulmonary artery endothelial cell adhesion and thrombotic remodeling. Methods: Network medicine was used to profile protein-protein interactions in hypoxia-treated human pulmonary artery endothelial cells. Data from liquid chromatography-mass spectrometry and microscale thermophoresis informed the development of a novel antibody (Ab) to inhibit platelet-endothelial adhesion, which was tested in cells from patients with chronic thromboembolic pulmonary hypertension (CTEPH) and three animal models in vivo. Measurements and Main Results: The protein NEDD9 was identified in the hypoxia thrombosome network in silico. Compared with normoxia, hypoxia (0.2% O2) for 24 hours increased HIF-1α (hypoxia-inducible factor-1α)-dependent NEDD9 upregulation in vitro. Increased NEDD9 was localized to the plasma-membrane surface of cells from control donors and patients with CTEPH. In endarterectomy specimens, NEDD9 colocalized with the platelet surface adhesion molecule P-selectin. Our custom-made anti-NEDD9 Ab targeted the NEDD9-P-selectin interaction and inhibited the adhesion of activated platelets to pulmonary artery endothelial cells from control donors in vitro and from patients with CTEPH ex vivo. Compared with control mice, platelet-pulmonary endothelial aggregates and pulmonary hypertension induced by ADP were decreased in NEDD9-/- mice or wild-type mice treated with the anti-NEDD9 Ab, which also decreased chronic pulmonary thromboembolic remodeling in vivo. Conclusions: The NEDD9-P-selectin protein-protein interaction is a modifiable target with which to inhibit platelet-pulmonary endothelial adhesion and thromboembolic vascular remodeling, with potential therapeutic implications for patients with disorders of increased hypoxia signaling pathways, including CTEPH.

The Inflammatory Profile of CTEPH-Derived Endothelial Cells Is a Possible Driver of Disease Progression

Chronic thromboembolic pulmonary hypertension (CTEPH) is a form of pulmonary hypertension characterized by the presence of fibrotic intraluminal thrombi and causing obliteration of the pulmonary arteries. Although both endothelial cell (EC) dysfunction and inflammation are linked to CTEPH pathogenesis, regulation of the basal inflammatory response of ECs in CTEPH is not fully understood. Therefore, in the present study, we investigated the role of the nuclear factor (NF)-κB pro-inflammatory signaling pathway in ECs in CTEPH under basal conditions. Basal mRNA levels of interleukin (IL)-8, IL-1β, monocyte chemoattractant protein-1 (MCP-1), C-C motif chemokine ligand 5 (CCL5), and vascular cell adhesion molecule-1 (VCAM-1) were upregulated in CTEPH-ECs compared to the control cells. To assess the involvement of NF-κB signaling in basal inflammatory activation, CTEPH-ECs were incubated with the NF-κB inhibitor Bay 11-7085. The increase in pro-inflammatory cytokines was abolished when cells were incubated with the NF-κB inhibitor. To determine if NF-κB was indeed activated, we stained pulmonary endarterectomy (PEA) specimens from CTEPH patients and ECs isolated from PEA specimens for phospho-NF-κB-P65 and found that especially the vessels within the thrombus and CTEPH-ECs are positive for phospho-NF-κB-P65. In summary, we show that CTEPH-ECs have a pro-inflammatory status under basal conditions, and blocking NF-κB signaling reduces the production of inflammatory factors in CTEPH-ECs. Therefore, our results show that the increased basal pro-inflammatory status of CTEPH-ECs is, at least partially, regulated through activation of NF-κB signaling and potentially contributes to the pathophysiology and progression of CTEPH.

Endothelial Dysfunction in Pulmonary Hypertension: Cause or Consequence?

Pulmonary arterial hypertension (PAH) is a rare, complex, and progressive disease that is characterized by the abnormal remodeling of the pulmonary arteries that leads to right ventricular failure and death. Although our understanding of the causes for abnormal vascular remodeling in PAH is limited, accumulating evidence indicates that endothelial cell (EC) dysfunction is one of the first triggers initiating this process. EC dysfunction leads to the activation of several cellular signalling pathways in the endothelium, resulting in the uncontrolled proliferation of ECs, pulmonary artery smooth muscle cells, and fibroblasts, and eventually leads to vascular remodelling and the occlusion of the pulmonary blood vessels. Other factors that are related to EC dysfunction in PAH are an increase in endothelial to mesenchymal transition, inflammation, apoptosis, and thrombus formation. In this review, we outline the latest advances on the role of EC dysfunction in PAH and other forms of pulmonary hypertension. We also elaborate on the molecular signals that orchestrate EC dysfunction in PAH. Understanding the role and mechanisms of EC dysfunction will unravel the therapeutic potential of targeting this process in PAH.

IP-10 and MCP-1 as biomarkers associated with disease severity of COVID-19

Background

COVID-19 is a viral respiratory disease caused by the severe acute respiratory syndrome-Coronavirus type 2 (SARS-CoV-2). Patients with this disease may be more prone to venous or arterial thrombosis because of the activation of many factors involved in it, including inflammation, platelet activation and endothelial dysfunction. Interferon gamma inducible protein-10 (IP-10), monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein 1-alpha (MIP1α) are cytokines related to thrombosis. Therefore, this study focused on these three indicators in COVID-19, with the hope to find biomarkers that are associated with patients’ outcome.

Methods

This is a retrospective single-center study involving 74 severe and critically ill COVID-19 patients recruited from the ICU department of the Tongji Hospital in Wuhan, China. The patients were divided into two groups: severe patients and critically ill patients. The serum IP-10, MCP-1 and MIP1α level in both groups was detected using the enzyme-linked immunosorbent assay (ELISA) kit. The clinical symptoms, laboratory test results, and the outcome of COVID-19 patients were retrospectively analyzed.

Results

The serum IP-10 and MCP-1 level in critically ill patients was significantly higher than that in severe patients (P < 0.001). However, no statistical difference in MIP1α between the two groups was found. The analysis of dynamic changes showed that these indicators remarkably increased in patients with poor prognosis. Since the selected patients were severe or critically ill, no significant difference was observed between survival and death.

Conclusions

IP-10 and MCP-1 are biomarkers associated with the severity of COVID-19 disease and can be related to the risk of death in COVID-19 patients.

Preoperative C-reactive protein predicts early postoperative outcomes after pulmonary endarterectomy in patients with chronic thromboembolic pulmonary hypertension

OBJECTIVE

To determine whether preoperative systemic inflammation (defined by C-reactive protein [CRP] levels ≥10 mg/L) is associated with worse functional and hemodynamic status and poor early outcomes postendarterectomy in patients with chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

This study included 159 patients who underwent pulmonary endarterectomy from 2009 to 2013 (derivation cohort) and 238 patients from 2015 to 2016 (validation cohort) with CRP data from the national CTEPH registry. The correlations between proinflammatory markers (CRP, interleukins 1 and 6, fibrinogen, and leukocytes) and hemodynamics were assessed in the derivation cohort. Pre-, perioperative characteristics, and 30-day outcomes (ie, death or lung transplant or extracorporeal membrane oxygenation need or inotropic or vasopressor need ≥3 days) of patients with CRP levels ≥ or <10 mg/L were compared.

RESULTS

Median age of the derivation cohort was 63 [52-73] years with 48% female, 80% in New York Heart Association class III/IV. The validation cohort had similar demographics and disease severity. Patients with CRP ≥10 mg/L had greater resistance levels and lower cardiac index than those with CRP <10 mg/L in both cohorts. The primary endpoint was reached in 38% (derivation) and 42% (validation) of patients. In multivariable logistic regression analysis, CRP ≥10 mg/L was associated with the primary endpoint in both the derivation cohort (odd ratio, 2.49 [1.11-5.61], independently of New York Heart class class IV and aortic clamping duration) and the validation cohort (odd ratio, 1.89 [1.09-3.61], independently of age and aortic clamping duration).

CONCLUSIONS

Preoperative CRP ≥10 mg/L is independently associated with adverse early outcomes postendarterectomy.

Pulmonary endarterectomy in a 12-year-old boy with multiple comorbidities

A 10-year-old boy, with multiple comorbidities presented with fever, exertional dyspnea, fatigue and an obliterated brachiocephalic and inferior caval vein. Chronic thromboembolic pulmonary hypertension (CTEPH) was diagnosed. Nadroparine, antibiotics and supplemental oxygen were successfully started. Aged 12 years, supplemental oxygen was permanently needed with progressive exertional dyspnea and fatigue. In the country of residence the patient was considered as inoperable. The right ventricle was severely dilated, hypocontractile and hypertrophic. Mean pulmonary artery pressure (mPAP) was 79 mmHg and cardiac output 2.2 L/min. Pulmonary endarterectomy was uneventful. Four days later, mPAP was 33 mmHg and cardiac output 6.4 L/min. Three months later the boy restarted his education without supplemental oxygen. Six months after surgery right ventricular size and function and mPAP (14 mmHg) were normal. We demonstrated that pulmonary endarterectomy in young aged children is feasible and well-tolerated, even in the presence of severe co-morbidities. CTEPH should be an important diagnostic consideration in symptomatic children with a known hypercoaguable state, a history of thrombo-embolism or venous catheter placement, and/or a diagnosis of pulmonary hypertension. Hesitating to refer children for surgical consideration, or attempting to treat them by medication, only postpones the single potentially curable treatment and may worsen their prognosis.

ICAM-1 promotes the abnormal endothelial cell phenotype in chronic thromboembolic pulmonary hypertension

BACKGROUND

Pulmonary endothelial cells play a key role in the pathogenesis of Chronic Thromboembolic Pulmonary Hypertension (CTEPH). Increased synthesis and/or the release of intercellular adhesion molecule-1 (ICAM-1) by pulmonary endothelial cells of patients with CTEPH has been recently reported, suggesting a potential role for ICAM-1 in CTEPH.

METHODS

We studied pulmonary endarterectomy specimens from 172 patients with CTEPH and pulmonary artery specimens from 97 controls undergoing lobectomy for low-stage cancer without metastasis.

RESULTS

ICAM-1 was overexpressed in vitro in isolated and cultured endothelial cells from endarterectomy specimens. Endothelial cell growth and apoptosis resistance were significantly higher in CTEPH specimens than in the controls (p < 0.001). Both abnormalities were abolished by pharmacological inhibition of ICAM-1 synthesis or activity. The overexpression of ICAM-1 contributed to the acquisition and maintenance of abnormal EC growth and apoptosis resistance via the phosphorylation of SRC, p38 and ERK1/2 and the overproduction of survivin. Regarding the ICAM-1 E469K polymorphism, the KE heterozygote genotype was significantly more frequent in CTEPH than in the controls, but it was not associated with disease severity among patients with CTEPH.

CONCLUSIONS

ICAM-1 contributes to maintaining the abnormal endothelial cell phenotype in CTEPH.

Chronic Thromboembolic Pulmonary Hypertension: Epidemiology, Diagnosis, and Management

Chronic thromboembolic pulmonary hypertension (CTEPH), classified as World Health Organization (WHO) group 4 pulmonary hypertension (PH), is an interesting and rare pulmonary vascular disorder secondary to mechanical obstruction of the pulmonary vasculature from thromboembolism resulting in PH. The pathophysiology is complex, beginning with mechanical obstruction of the pulmonary arteries, which eventually leads to arteriopathic changes and vascular remodeling in the nonoccluded arteries and in the distal segments of the occluded arteries mediated by thrombus nonresolution, abnormal angiogenesis, endothelial dysfunction, and various local growth factors. Based on available data, CTEPH is a rare disease entity occurring in a small proportion (0.5-3%) of patients after acute pulmonary embolism with an annual incidence ranging anywhere between 1 and 7 cases per million population. It is often underdiagnosed or misdiagnosed as idiopathic pulmonary arterial hypertension due to a lack of clinical suspicion or the under-utilization of radionuclide ventilation/perfusion scan. Although the current standard remains planar ventilation/perfusion scintigraphy as the initial imaging study to screen for CTEPH, and invasive pulmonary angiography with right heart catheterization as confirmatory modalities, they are likely to be replaced by modalities that can provide both anatomic and functional data while minimizing radiation exposure. Surgery is the gold standard treatment and offers better improvements in clinical and hemodynamic parameters compared with medical therapy. The management of CTEPH requires a multidisciplinary team, operability assessment, experienced surgical center, and the consideration of medical PH-directed therapies in patients who have inoperable disease, in addition to supportive therapies. Although, balloon pulmonary angioplasty is gaining interest to improve pulmonary hemodynamics and symptoms in CTEPH patients not amenable to surgery, further investigative randomized studies are needed to validate its use. It is very important for the present-day physician to be familiar with the disease entity and its appropriate evaluation to facilitate early diagnosis and appropriate management.

Impact of the initiation of balloon pulmonary angioplasty program on referral of patients with chronic thromboembolic pulmonary hypertension to surgery

BACKGROUND

Balloon pulmonary angioplasty (BPA) is a technique proposed for inoperable patients with chronic thromboembolic pulmonary hypertension (CTEPH). In this study we aimed to determine whether initiation of the BPA program has modified the characteristics and outcome of patients undergoing pulmonary endarterectomy (PEA), and compared the characteristics of patients undergoing one or the other procedure.

METHODS

This prospective registry study included all patients with CTEPH who underwent PEA in the French National Reference Center before (2012 to 2013) and after (2015 to 2016) BPA program initiation (February 2014). Pre-operative clinical and hemodynamics profiles, peri-operative (Jamieson classification, surgery duration, need of assistance) characteristics of both groups, and all-cause mortality were compared using the t-test or chi-square test. Characteristics of patients subjected to surgery or BPA since February 2014 were also compared.

RESULTS

The total number of patients referred to the CTEPH team increased in the BPA era (n = 291 vs n = 484). The pre-operative characteristics of patients from the pre-BPA era (n = 240) were similar to those from the BPA era (n = 246). Despite more Jamieson Type 3 cases (29%) in the second period, 30- and 90-day mortality remained stable (both p > 0.30). Patients subjected to BPA (n = 177) were older than those subjected to PEA (n = 364) (64 ± 14 vs 60 ± 14 years, respe`ctively), and had higher rates of splenectomy (10% vs 1%) or implantable port (9% vs 3%), lower total pulmonary resistance, better cardiac index, and better renal function (all p < 0.01).

CONCLUSIONS

This study shows the influence of the initiation of the BPA program on the profile of patients with CTEPH undergoing PEA.