The significance of CD16+ monocytes in the occurrence and development of chronic thromboembolic pulmonary hypertension: insights from single-cell RNA sequencing.

Background: Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious pulmonary vascular disease characterized by residual thrombi in the pulmonary arteries and distal pulmonary microvascular remodeling. The pathogenesis of CTEPH remains unclear, but many factors such as inflammation, immunity, coagulation and angiogenesis may be involved. Monocytes are important immune cells that can differentiate into macrophages and dendritic cells and play an important role in thrombus formation. However, the distribution, gene expression profile and differentiation trajectory of monocyte subsets in CTEPH patients have not been systematically studied. This study aims to reveal the characteristics and functions of monocytes in CTEPH patients using single-cell sequencing technology, and to provide new insights for the diagnosis and treatment of CTEPH. Methods: Single-cell RNA sequencing (scRNA-seq) were performed to analyze the transcriptomic features of peripheral blood mononuclear cells (PBMCs) from healthy controls, CTEPH patients and the tissues from CTEPH patients after the pulmonary endarterectomy (PEA). We established a CTEPH rat model with chronic pulmonary embolism caused by repeated injection of autologous thrombi through a central venous catheter, and used flow cytometry to detect the proportion changes of monocyte subsets in CTEPH patients and CTEPH rat model. We also observed the infiltration degree of macrophage subsets in thrombus tissue and their differentiation relationship with peripheral blood monocyte subsets by immunofluorescence staining. Results: The results showed that the monocyte subsets in peripheral blood of CTEPH patients changed significantly, especially the proportion of CD16+ monocyte subset increased. This monocyte subset had unique functional features at the transcriptomic level, involving processes such as cell adhesion, T cell activation, coagulation response and platelet activation, which may play an important role in pulmonary artery thrombus formation and pulmonary artery intimal remodeling. In addition, we also found that the macrophage subsets in pulmonary endarterectomy tissue of CTEPH patients showed pro-inflammatory and lipid metabolism reprogramming features, which may be related to the persistence and insolubility of pulmonary artery thrombi and the development of pulmonary hypertension. Finally, we also observed that CD16+ monocyte subset in peripheral blood of CTEPH patients may be recruited to pulmonary artery intimal tissue and differentiate into macrophage subset with high expression of IL-1ß, participating in disease progression. Conclusion: CD16+ monocytes subset had significant gene expression changes in CTEPH patients, related to platelet activation, coagulation response and inflammatory response. And we also found that these cells could migrate to the thrombus and differentiate into macrophages with high expression of IL-1ß involved in CTEPH disease progression. We believe that CD16+ monocytes are important participants in CTEPH and potential therapeutic targets.

Cardiovascular Manifestations in Behçet's Disease.

Cardiovascular involvement in Behçet's disease (BD) is considerably related to morbidity and mortality. However, the cardiovascular manifestation is sometimes difficult to distinguish from those of other causes. The suspicion of BD and proper treatment is pivotal in the management of BD. Histology demonstrates perivasculitis. Neutrophil seems to play an important role in the inflammation of BD. It is thought that inflammation causes venous thrombosis and arterial aneurysm. Characteristically, BD involves both arteries and veins of variable size in any region. Venous thrombosis needs immunosuppression, and inferior vena cava thrombosis and Budd-Chiari syndrome require intensive immunosuppressive therapy. Arterial involvement causes aneurysm which usually is treated by surgical or endovascular intervention with immunosuppression. Pulmonary artery aneurysm and cardiac involvement require multimodal managements.

The Impact of Highly Selective Thoracic Sympathectomy on the Progression of Monocrotaline-induced Pulmonary Arterial Hypertension in Rats.

ABSTRACT: Pulmonary arterial hypertension (PAH) is characterized by persistently elevated pulmonary artery pressure and vascular resistance. Sympathetic overactivity in hypertension participates in pulmonary vascular remodeling and heart failure. The present study aims to explore the efficacy of highly selective thoracic sympathectomy (HSTS) on lowering pulmonary artery pressure, reversing pulmonary vascular remodeling, and improving right ventricular function in rats. A total of 24 Sprague-Dawley rats were randomly assigned into the control group ( n = 8) and experimental group ( n = 16). Rats in the control group were intraperitoneally injected with 0.9% normal saline, and those in the experimental group were similarly administered with received monocrotaline (MCT) injections at 60 mg/kg. Two weeks later, rats in the experimental group were further subdivided randomly into the MCT-HSTS group ( n = 8) and MCT-sham group ( n = 8), and they were surgically treated with HSTS and sham operation, respectively. Two weeks later, significantly lowered mean pulmonary artery pressure (mPAP), pulmonary artery systolic pressure (sPAP), and the ratio of sPAP to femoral artery systolic pressure (sFAP) were detected in the MCT-HSTS group than those of the MCT-sham group. In addition, rats in the MCT-HSTS group presented a significantly lower ratio of vascular wall area to the total vascular area (WT%), right ventricular hypertrophy index, and degrees of right ventricular fibrosis and lung fibrosis in comparison to those of the MCT-sham group. HSTS significantly downregulated protein levels of inflammasomes in pulmonary artery smooth muscle cells (PASMCs). Collectively, HSTS effectively reduces pulmonary artery pressure, pulmonary arteriolar media hypertrophy, and right ventricular hypertrophy in MCT-induced PAH rats. It also exerts an anti-inflammatory effect on PASMCs in PAH rats by suppressing inflammasomes and the subsequent release of inflammatory cytokines.

Animal models of pulmonary arterial hypertension associated with atrial septal defect.

Pulmonary arterial hypertension (PAH) is a well-known complication of congenital heart disease (CHD). The lack of a satisfactory animal model for PAH associated with CHD (PAH-CHD) has limited progress in understanding the pathogenesis of PAH and the development of therapeutic agents. The development of a rat model for PAH associated with atrial septal defect (ASD) was achieved through atrial septal puncture and thermal ablation. Two and 4 weeks after modeling, hematoxylin and eosin staining showed that the vascular thickness, vascular thickness index, vascular area, and vascular area index in pulmonary arteries with an outer diameter of 50-300 µm in the PAH-ASD 2 and 4 weeks group were higher than those in the sham group (all P < 0.05). Alpha-smooth muscle actin (ɑ-SMA) staining showed that the medial thickness, medial thickness index, medial area, and medial area index in pulmonary arteries with an outer diameter of 50-300 µm at 2 and 4 weeks after modeling were significantly higher than those in the sham group (all P < 0.05). Additionally, mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) in the PAH-ASD 2 and 4 weeks groups were significantly higher than those in the sham group (both P < 0.05). Elastin van Gieson staining showed that the vascular obstruction score in the PAH-ASD 2 and 4 weeks group was significantly higher than that in the sham group (both P < 0.05). The PAH-ASD rats were successfully generated. These findings suggest that our model would be useful for further research into the pathogenesis, prevention, and treatment of PAH-ASD.

CircNAP1L4 regulates pulmonary artery smooth muscle cell proliferation via the NAP1L4-mediated super-enhancer-driven glycolysis gene hexokinase II (HK II) in pulmonary hypertension.

Glycolysis is a major determinant of pulmonary artery smooth muscle cell (PASMC) proliferation in pulmonary hypertension (PH). Circular RNAs (circRNAs) are powerful regulators of glycolysis in multiple diseases; however, the role of circRNAs in glycolysis in PH has been poorly characterized. The aim of this study was to uncover the regulatory mechanism of a new circRNA, circNAP1L4, in human pulmonary artery smooth muscle cell (HPASMC) proliferation through the host protein NAP1L4 to regulate the super-enhancer-driven glycolysis gene hexokinase II (HK II). CircNAP1L4 was downregulated in hypoxic HPASMCs and plasma of PH patients. Functionally, circNAP1L4 overexpression inhibited glycolysis and proliferation in hypoxic HPASMCs. Mechanistically, circNAP1L4 directly bound to its host protein NAP1L4 and affected the ability of NAP1L4 to move into the nucleus to regulate the epigenomic signals of the super-enhancer of HK II. Intriguingly, circNAP1L4 overexpression inhibited the proliferation but not the migration of human pulmonary arterial endothelial cells (HPAECs) cocultured with HPASMCs. Furthermore, pre-mRNA-processing-splicing Factor 8 (PRP8) was found to regulate the production ratio of circNAP1L4 and linear NAP1L4. In vivo, targeting circNAP1L4 alleviates SU5416 combined with hypoxia (SuHx)-induced PH. Overall, these findings reveal a new circRNA that inhibits PASMC proliferation and serves as a therapeutic target for PH.

Lactate dehydrogenase A (LDHA)-mediated lactate generation promotes pulmonary vascular remodeling in pulmonary hypertension.

BACKGROUND: High levels of lactate are positively associated with prognosis and mortality in pulmonary hypertension (PH). Lactate dehydrogenase A (LDHA) is a key enzyme for the production of lactate. This study is undertaken to investigate the role and molecular mechanisms of lactate and LDHA in PH. METHODS: Lactate levels were measured by a lactate assay kit. LDHA expression and localization were detected by western blot and Immunofluorescence. Proliferation and migration were determined by CCK8, western blot, EdU assay and scratch-wound assay. The right heart catheterization and right heart ultrasound were measured to evaluate cardiopulmonary function. RESULTS: In vitro, we found that lactate promoted proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) in an LDHA-dependent manner. In vivo, we found that LDHA knockdown reduced lactate overaccumulation in the lungs of mice exposed to hypoxia. Furthermore, LDHA knockdown ameliorated hypoxia-induced vascular remodeling and right ventricular dysfunction. In addition, the activation of Akt signaling by hypoxia was suppressed by LDHA knockdown both in vivo and in vitro. The overexpression of Akt reversed the inhibitory effect of LDHA knockdown on proliferation in PASMCs under hypoxia. Finally, LDHA inhibitor attenuated vascular remodeling and right ventricular dysfunction in Sugen/hypoxia mouse PH model, Monocrotaline (MCT)-induced rat PH model and chronic hypoxia-induced mouse PH model. CONCLUSIONS: Thus, LDHA-mediated lactate production promotes pulmonary vascular remodeling in PH by activating Akt signaling pathway, suggesting the potential role of LDHA in regulating the metabolic reprogramming and vascular remodeling in PH.

Unraveling the Impact of miR-146a in Pulmonary Arterial Hypertension Pathophysiology and Right Ventricular Function.

Pulmonary arterial hypertension (PAH) is a chronic disorder characterized by excessive pulmonary vascular remodeling, leading to elevated pulmonary vascular resistance and right ventricle (RV) overload and failure. MicroRNA-146a (miR-146a) promotes vascular smooth muscle cell proliferation and vascular neointimal hyperplasia, both hallmarks of PAH. This study aimed to investigate the effects of miR-146a through pharmacological or genetic inhibition on experimental PAH and RV pressure overload animal models. Additionally, we examined the overexpression of miR-146a on human pulmonary artery smooth muscle cells (hPASMCs). Here, we showed that miR-146a genic expression was increased in the lungs of patients with PAH and the plasma of monocrotaline (MCT) rats. Interestingly, genetic ablation of miR-146a improved RV hypertrophy and systolic pressures in Sugen 5415/hypoxia (SuHx) and pulmonary arterial banding (PAB) mice. Pharmacological inhibition of miR-146a improved RV remodeling in PAB-wild type mice and MCT rats, and enhanced exercise capacity in MCT rats. However, overexpression of miR-146a did not affect proliferation, migration, and apoptosis in control-hPASMCs. Our findings show that miR-146a may play a significant role in RV function and remodeling, representing a promising therapeutic target for RV hypertrophy and, consequently, PAH.

Urolithin A Protects against Hypoxia-Induced Pulmonary Hypertension by Inhibiting Pulmonary Arterial Smooth Muscle Cell Pyroptosis via AMPK/NF-κB/NLRP3 Signaling.

Recent studies confirmed that pyroptosis is involved in the progression of pulmonary hypertension (PH), which could promote pulmonary artery remodeling. Urolithin A (UA), an intestinal flora metabolite of ellagitannins (ETs) and ellagic acid (EA), has been proven to possess inhibitory effects on pyroptosis under various pathological conditions. However, its role on PH remained undetermined. To investigate the potential of UA in mitigating PH, mice were exposed to hypoxia (10% oxygen, 4 weeks) to induce PH, with or without UA treatment. Moreover, in vitro experiments were carried out to further uncover the underlying mechanisms. The in vivo treatment of UA suppressed the progression of PH via alleviating pulmonary remodeling. Pyroptosis-related genes were markedly upregulated in mice models of PH and reversed after the administration of UA. In accordance with that, UA treatment significantly inhibited hypoxia-induced pulmonary arterial smooth muscle cell (PASMC) pyroptosis via the AMPK/NF-κB/NLRP3 pathway. Our results revealed that UA treatment effectively mitigated PH progression through inhibiting PASMC pyroptosis, which represents an innovative therapeutic approach for PH.

Emerging connectivity of programmed cell death pathways and pulmonary vascular remodelling during pulmonary hypertension.

Pulmonary hypertension (PH) is a chronic progressive vascular disease characterized by abnormal pulmonary vascular resistance and pulmonary artery pressure. The major structural alteration during PH is pulmonary vascular remodelling, which is mainly caused by the imbalance between proliferation and apoptosis of pulmonary vascular cells. Previously, it was thought that apoptosis was the only type of programmed cell death (PCD). Soon afterward, other types of PCD have been identified, including autophagy, pyroptosis, ferroptosis and necroptosis. In this review, we summarize the role of the above five forms of PCD in mediating pulmonary vascular remodelling, and discuss their guiding significance for PH treatment. The current review could provide a better understanding of the correlation between PCD and pulmonary vascular remodelling, contributing to identify new PCD-associated drug targets for PH.

The role and mechanism of thrombospondin-4 in pulmonary arterial hypertension associated with congenital heart disease.

BACKGROUND: Due to a special hemodynamic feature, pulmonary vascular disease in pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD) has two stages: reversible and irreversible. So far, the mechanism involved in the transition from reversible to irreversible stage is elusive. Moreover, no recognized and reliable assessments to distinguish these two stages are available. Furthermore, we found that compared with control and reversible PAH, thrombospondin-4 (THBS4) was significantly upregulated in irreversible group by bioinformatic analysis. Hence, we further verify and investigate the expression and role of THBS4 in PAH-CHD. METHODS: We established the monocrotaline plus aorto-cava shunt-induced (MCT-AV) rat model. We measured the expression of THBS4 in lung tissues from MCT-AV rats. Double immunofluorescence staining of lung tissue for THBS4 and α-SMA (biomarker of smooth muscle cells) or vWF (biomarker of endothelial cells) to identify the location of THBS4 in the pulmonary artery. Primary pulmonary artery smooth muscle cells (PASMCs) were cultivated, identified, and used in this study. THBS4 was inhibited and overexpressed by siRNA and plasmid, respectively, to explore the effect of THBS4 on phenotype transformation, proliferation, apoptosis, and migration of PASMCs. The effect of THBS4 on pulmonary vascular remodeling was evaluated in vivo by adeno-associated virus which suppressed THBS4 expression. Circulating level of THBS4 in patients with PAH-CHD was measured by ELISA. RESULTS: THBS4 was upregulated in the lung tissues of MCT-AV rats, and was further upregulated in severe pulmonary vascular lesions. And THBS4 was expressed mainly in PASMCs. When THBS4 was inhibited, contractile markers α-SMA and MYH11 were upregulated, while the proliferative marker PCNA was decreased, the endothelial-mensenchymal transition marker N-cad was downregulated, proapototic marker BAX was increased. Additionally, proliferation and migration of PASMCs was inhibited and apoptosis was increased. Conversely, THBS4 overexpression resulted in opposite effects. And the impact of THBS4 on PASMCs was probably achieved through the regulation of the PI3K/AKT pathway. THBS4 suppression attenuated pulmonary vascular remodeling. Furthermore, compared with patients with simple congenital heart disease and mild PAH-CHD, the circulating level of THBS4 was higher in patients with severe PAH-CHD. CONCLUSIONS: THBS4 is a promising biomarker to distinguish reversible from irreversible PAH-CHD before repairing the shunt. THBS4 is a potential treatment target in PAH-CHD, especially in irreversible stage.

Levosimendan mediates the BMP/Smad axis through upregulation of circUSP34-targeted miR-1298 to alleviate pulmonary hypertension.

BACKGROUND: Pulmonary hypertension (PH) is a long-term disease that impacts approximately 1% of the world's population. Currently, levosimendan (Lev) is proposed for PH treatment. However, the mechanism of Lev in the treatment of PH is unknown. METHODS: We used hypoxia-induced pulmonary artery smooth muscle cells (PASMCs) to establish a PH cell model. A number of cell biology methods were performed to assay alterations in cell proliferation, migration and apoptosis after Lev treatment. qRT-PCR and WB were performed to test the levels of circUSP34 and miR-1298, and BMP/Smad protein respectively. In addition, the regulatory relationship between circUSP34 or BMPR2 with miR-1298 was verified through the use of double luciferase as well as RIP assay. In addition, we explored the regulatory effect of Lev on the circUSP34/miR-1298/BMP/Smad axis using a rat PH model. RESULTS: Our results demonstrate that Lev inhibited PASMCs cell proliferation, migration and promoted apoptosis exposed to hypoxia. In hypoxia-treated PASMCs, circUSP34 expression got downregulated while miR-1298 upregulated, whereas the addition with Lev resulted in upregulation of circUSP34 expression and downregulation of miR-1298 expression, indicating that circUSP34 can target and regulate miR-1298. In addition, miR-1298 targets and regulates the expression of BMPR2. In a rat PH model induced by hypoxia combined with SU5416, Lev upregulated circUSP34 targeting miR-1298-mediated BMP/Smad axis to alleviate the PH phenotype. CONCLUSION: We have shown that Lev can be used as a therapeutic drug for PH patients, which works through the circUSP34/miR-1298/BMP/Smad axis to alleviate PH symptoms.

MFN2-dependent mitochondrial dysfunction contributes to Relm-ß-induced pulmonary arterial hypertension via USP18/Twist1/miR-214 pathway.

Induction of resistin-like molecule ß (Relm-ß) and mitofusin 2 (MFN2) mediated aberrant mitochondrial fission have been found to be involved in the pathogenesis of pulmonary arterial hypertension (PAH). However, the molecular mechanisms underlying Relm-ß regulation of MFN2 therefore mitochondrial fission remain unclear. This study aims to address these issues. Primary cultured PASMCs and monocrotaline (MCT)-induced PAH rats were applied in this study. The results showed that Relm-ß promoted cells proliferation in PASMCs, this was accompanied with the upregulation of USP18, Twist1 and miR-214, and downregulation of MFN2. We found that Relm-ß increased USP18 expression which in turn raised Twist1 by suppressing its proteasome degradation. Elevation of Twist1 increased miR-214 expression and then reduced MFN2 expression and mitochondrial fragmentation leading to PASMCs proliferation. In vivo study, we confirmed that Relm-ß was elevated in MCT-induced PAH rat model, and USP18/Twist1/miR-214/MFN2 axis was altered similar as in vitro. Targeting this cascade by Relm-ß receptor inhibitor Calhex231, proteasome inhibitor MG-132, Twist1 inhibitor Harmine or miR-214 antagomiR prevented the development of pulmonary vascular remodeling and therefore PAH in MCT-treated rats. In conclusion, we demonstrate that Relm-ß promotes PASMCs proliferation and vascular remodeling by activating USP18/Twist1/miR-214 dependent MFN2 reduction and mitochondrial fission, suggesting that this signaling pathway might be a promising target for management of PAH.

A spotlight on the aged pulmonary artery.

The ever-increasing life expectancy of the global population introduces a critical perspective on the impact of aging as an immutable cardiovascular risk factor, particularly manifesting in the alterations observed in the pulmonary artery (PA). Mechanisms contributing to aging-induced changes in PA include endothelial dysfunction, chronic inflammation, and structural changes in the arterial wall over time. These alterations extend beyond mere elasticity, exerting profound effects on pulmonary hemodynamics. The propensity of PAs to develop atherosclerotic plaques underscores an intriguing facet of vascular aging, although the available literature is currently insufficient to comprehensively assess their true incidence. While recognizing the inherent risk of periprocedural complications, right heart catheterization (RHC) stands out as the gold standard for precise hemodynamic evaluation. Echocardiography, a widely employed method, proves valuable for screening pulmonary hypertension (PH), yet falls short of diagnostic capability. Technological advancements usher in a new era with non-invasive modalities such as cardiac magnetic resonance (CMR) imaging emerging as promising tools. These innovations demonstrate their prowess in providing accurate assessments of PA stiffness and hemodynamics, offering a glimpse into the future landscape of diagnostic methodologies. As we navigate the intersection of aging and pulmonary vascular health, this review aims to address mechanisms and techniques for assessing PA aging, highlighting the need for comprehensive assessments to guide clinical decision making in an increasingly aging population.

Aquaporin 1 confers apoptosis resistance in pulmonary arterial smooth muscle cells from the SU5416 hypoxia rat model.

Pulmonary hypertension (PH) arises from increased pulmonary vascular resistance due to contraction and remodeling of the pulmonary arteries. The structural changes include thickening of the smooth muscle layer from increased proliferation and resistance to apoptosis. The mechanisms underlying apoptosis resistance in PH are not fully understood. In cancer cells, high expression of aquaporin 1 (AQP1), a water channel, is associated with apoptosis resistance. We showed AQP1 protein was expressed in pulmonary arterial smooth muscle cells (PASMCs) and upregulated in preclinical PH models. In this study, we used PASMCs isolated from control male rats and the SU5416 plus hypoxia (SuHx) model to test the role of AQP1 in modulating susceptibility to apoptosis. We found the elevated level of AQP1 in PASMCs from SuHx rats was necessary for resistance to apoptosis and that apoptosis resistance could be conferred by increasing AQP1 in control PASMCs. In exploring the downstream pathways involved, we found AQP1 levels influence the expression of Bcl-2, with enhanced AQP1 levels corresponding to increased Bcl-2 expression, reducing the ratio of BAX to Bcl-2, consistent with apoptosis resistance. These results provide a mechanism by which AQP1 can regulate PASMC fate.

TGFß1, SMAD and ß-catenin in pulmonary arteries of smokers, patients with small airway disease and COPD: potential drivers of EndMT.

We previously reported pulmonary arterial remodelling and active endothelial-to-mesenchymal transition (EndMT) in smokers and patients with early chronic obstructive pulmonary disease (COPD). In the present study, we aimed to evaluate the role of different drivers of EndMT. Immunohistochemical staining for EndMT drivers, TGF-ß1, pSMAD-2/3, SMAD-7, and ß-catenin, was performed on lung resections from 46 subjects. Twelve were non-smoker-controls (NC), six normal lung function smokers (NLFS), nine patients with small-airway diseases (SAD), nine mild-moderate COPD-current smokers (COPD-CS) and ten COPD-ex-smokers (COPD-ES). Histopathological measurements were done using Image ProPlus softwarev7.0. We observed lower levels of total TGF-ß1 (P<0.05) in all smoking groups than in the non-smoking control (NC). Across arterial sizes, smoking groups exhibited significantly higher (P<0.05) total and individual layer pSMAD-2/3 and SMAD-7 than in the NC group. The ratio of SAMD-7 to pSMAD-2/3 was higher in COPD patients compared with NC. Total ß-catenin expression was significantly higher in smoking groups across arterial sizes (P<0.05), except for COPD-ES and NLFS groups in small and medium arteries, respectively. Increased total ß-catenin was positively correlated with total S100A4 in small and medium arteries (r = 0.35, 0.50; P=0.02, 0.01, respectively), with Vimentin in medium arteries (r = 0.42, P=0.07), and with arterial thickness of medium and large arteries (r = 0.34, 0.41, P=0.02, 0.01, respectively). This is the first study uncovering active endothelial SMAD pathway independent of TGF-ß1 in smokers, SAD, and COPD patients. Increased expression of ß-catenin indicates its potential interaction with SMAD pathway, warranting further research to identify the deviation of this classical pathway.

Cell Death in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a severe pulmonary vascular disease characterized by increased pulmonary vascular resistance because of vascular remodeling and vasoconstriction. Subsequently, PAH leads to right ventricular hypertrophy and heart failure. Cell death mechanisms play a significant role in development and tissue homeostasis, and regulate the balance between cell proliferation and differentiation. Several basic and clinical studies have demonstrated that multiple mechanisms of cell death, including pyroptosis, apoptosis, autophagy, ferroptosis, anoikis, parthanatos, and senescence, are closely linked with the pathogenesis of PAH. This review summarizes different cell death mechanisms involved in the death of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs), the primary target cells in PAH. This review summarizes the role of these cell death mechanisms, associated signaling pathways, unique effector molecules, and various pro-survival or reprogramming mechanisms. The aim of this review is to summarize the currently known molecular mechanisms underlying PAH. Further investigations of the cell death mechanisms may unravel new avenues for the prevention and treatment of PAH.

Investigation into the role of H2-Ab1 in vascular remodeling in pulmonary arterial hypertension via Bioinformatics.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a progressive disease of vascular remodeling characterized by persistent pulmonary arterial pressure elevation, which can lead to right heart failure and premature death. Given the complex pathogenesis and poor prognosis of PAH, the identification and investigation of biomarkers become increasingly critical for advancing further understanding of the disease. METHODS: PAH-related datasets, GSE49114, GSE180169 and GSE154959, were downloaded from the publicly available GEO database. By performing WGCNA on the GSE49114 dataset, a total of 906 PAH-related key module genes were screened out. By carrying out differential analysis on the GSE180169 dataset, a total of 576 differentially expressed genes were identified. Additionally, the GSE154959 single-cell sequencing dataset was also subjected to differential analysis, leading to the identification of 34 DEGs within endothelial cells. By taking intersection of the above three groups of DEGs, five PAH-related hub genes were screened out, namely Plvap, Cyp4b1, Foxf1, H2-Ab1, and H2-Eb1, among which H2-Ab1 was selected for subsequent experiments. RESULTS: A SuHx mouse model was prepared using the SU5416/hypoxia method, and the successful construction of the model was evaluated through Hematoxylin-Eosin staining, hemodynamic detection, fulton index, and Western Blot (WB). The results of WB and qRT-PCR demonstrated a significant upregulation of H2-Ab1 expression in SuHx mice. Consistent with the results of bioinformatics analysis, a time-dependent increase was observed in H2-Ab1 expression in hypoxia-treated mouse pulmonary artery endothelial cells (PAECs). To investigate whether H2-Ab1 affects the development and progression of PAH, we knocked down H2-Ab1 expression in PAECs, and found that its knockdown inhibited the viability, adhesion, migration, and angiogenesis, while concurrently promoted the apoptosis of PAECs. CONCLUSION: H2-Ab1 could regulate the proliferation, apoptosis, adhesion, migration, and angiogenesis of PAECs.

The Correlation between Lung Ultrasound and Pathology in Rat Model of Monocrotaline-Induced Pulmonary Hypertension.

Pulmonary hypertension (PH) is a progressive and complex pulmonary vascular disease with poor prognosis. The aim of this study was to provide a new understanding of the lung pathology of disease and a noninvasive method in monitoring the establishment of animal models for basic and clinical studies of PH, indeed to explore clinical application value of lung ultrasound for patients with PH. Totally 32 male SD rats were randomly divided into control group, MCT (monocrotaline) group, PDTC (pyrrolidine dithiocarbamate) group, and NS (normal saline) group. Rats in the MCT group, PDTC group, and NS group received single intraperitoneal injection of MCT, while the control group received the same dose of NS. Then, PDTC group and NS group received PDTC and NS daily for treatment at the end of the model. Each group received lung ultrasound examination and measurement of pulmonary arterial pressure (PAP). Then, the rats were sacrificed to take the lung specimens to being observed. The ultrasound and pathological results were analyzed with a semiquantitative score. With the pulmonary artery pressure increases, the MCT group had a higher pulmonary ultrasound score and pathological score compared with the control group (p < 0.05). After PDTC treatment, the pulmonary ultrasound score and the pathological score decline (p < 0.05). We investigated both lung ultrasound scores, and the pathological scores were positively correlated with mean pulmonary artery pressure (mPAP) (both r > 0.8, p < 0.0001). Moreover, lung ultrasound scores were positively correlated with pathological scores (r > 0.8, p < 0.0001). We elucidated lung ultrasound evaluation providing more evidence for the management of PH in the rat model. Moreover, lung ultrasound provided a noninvasive method in monitoring the establishment of animal models for basic and clinical studies of PH.

Indigo Leaves-Induced Pulmonary Arterial Remodeling without Right Ventricular Hypertrophy in Rats.

Indigo naturalis (IN), derived from the leaves of the indigo plant, is a traditional Chinese medicine that has historically been used for its anti-inflammatory properties in the treatment of various diseases, including ulcerative colitis (UC). However, long-term use of IN in UC patients is incontrovertibly associated with the onset of pulmonary arterial hypertension (PAH). To investigate the mechanisms by which IN induces PAH, we focused on the raw material of IN, indigo leaves (IL). Only the condition of long-term chronic (6 months) and high-dose (containing 5% IL in the control diet) administration of IL induced medial thickening in the pulmonary arteries without right ventricular hypertrophy in our rat model. IL administration for a month did not induce pulmonary arterial remodeling but increased endothelin-1 (ET-1) expression levels within endothelial cell (EC) layers in the lungs. Gene Expression Omnibus analysis showed that ET-1 is a key regulator of PAH and that the IL component indican and its metabolite IS induced ET-1 mRNA expression via reactive oxygen species-dependent mechanism. We identified the roles of indican and IS in ET-1 expression in ECs, which were linked to pulmonary arterial remodeling in an animal model.