Electrocardiographic Prognostic Marker in Pulmonary Arterial Hypertension: RS Time. / Marcador Prognóstico Eletrocardiográfico na Hipertensão Arterial Pulmonar: Tempo de RS.

BACKGROUND: Pulmonary hypertension is a condition that involves the remodeling of the right ventricle. Ongoing remodeling is also associated with disease prognosis. During the restructuring process, complex changes such as hypertrophy and dilatation may also be reflected in electrocardiographic parameters. OBJECTIVES: Our study aimed to investigate the relationship between prognosis and electrocardiographic parameters in patients with pulmonary arterial hypertension. METHODS: The study was designed retrospectively and included patients diagnosed with pulmonary arterial hypertension between 2010 and 2022. The patients were divided into two groups based on their survival outcome. Various parameters, including electrocardiographic, demographic, echocardiographic, catheter, and blood parameters, were compared between the two groups. A p-value of <0.05 was considered statistically significant. RESULTS: In the multivariate Cox analyses, the parameters that were found to be independently associated with survival were the 6-minute walk test, mean pulmonary artery pressure, presence of pericardial effusion, and time between the beginning of the QRS and the peak of the S wave (RS time) (p<0.05 for each). Of all the parameters, RS time demonstrated the best diagnostic performance (AUC:0.832). In the survival analysis, a significant correlation was found between RS time and survival when using a cut-off value of 59.5 ms (HR: 0.06 [0.02-0.17], p < 0.001). CONCLUSIONS: According to the results of our study, a longer RS time is associated with poor prognosis in patients with pulmonary arterial hypertension. We can obtain information about the course of the disease with a simple, non-invasive parameter.

FUNDAMENTO: A hipertensão pulmonar é uma condição que envolve a remodelação do ventrículo direito. A remodelação contínua também está associada ao prognóstico da doença. Durante o processo de reestruturação, alterações complexas como hipertrofia e dilatação também podem se refletir nos parâmetros eletrocardiográficos. OBJETIVOS: Nosso estudo teve como objetivo investigar a relação entre prognóstico e parâmetros eletrocardiográficos em pacientes com hipertensão arterial pulmonar. MÉTODOS: O estudo foi desenhado retrospectivamente e incluiu pacientes com diagnóstico de hipertensão arterial pulmonar entre 2010 e 2022. Os pacientes foram divididos em dois grupos com base no resultado de sobrevida. Vários parâmetros, incluindo parâmetros eletrocardiográficos, demográficos, ecocardiográficos, de cateter e sanguíneos, foram comparados entre os dois grupos. Um valor de p <0,05 foi considerado estatisticamente significativo. RESULTADOS: Na análise multivariada de Cox, os parâmetros que se mostraram independentemente associados à sobrevida foram o teste de caminhada de 6 minutos, pressão média da artéria pulmonar, presença de derrame pericárdico e tempo entre o início do QRS e o pico da onda S (tempo de RS) (p<0,05 para cada). De todos os parâmetros, o tempo de RS demonstrou o melhor desempenho diagnóstico (AUC: 0,832). Na análise de sobrevida, foi encontrada correlação significativa entre o tempo de RS e a sobrevida ao utilizar o valor de corte de 59,5 ms (HR: 0,06 [0,02-0,17], p < 0,001). CONCLUSÕES: De acordo com os resultados do nosso estudo, um tempo de RS mais longo está associado a um pior prognóstico em pacientes com hipertensão arterial pulmonar. Podemos obter informações sobre o curso da doença com um parâmetro simples e não invasivo.

Prognostic impact of right atrial strain in systemic lupus erythematosus with pulmonary arterial hypertension.

OBJECTIVE: The aim of this study was to assess right atrial (RA) function, including RA phase strain, via speckle-tracking echocardiography (STE) in a cohort of systemic lupus erythematosus (SLE) patients with pulmonary arterial hypertension (PAH) and in particular to explore the relationship between RA phase strain and the occurrence of cardiovascular events. METHODS: STE analyses of RA function were evaluated in patients with SLE-PAH and in 33 healthy control subjects. Clinical associations, serum biomarkers, echocardiographic data, survival times, and adverse cardiovascular events were evaluated. RESULTS: A total of 66 patients with SLE-PAH were enrolled; they were divided into two groups based on the occurrence of adverse clinical events. RA phase strain was significantly reduced in patients with events than in patients without events. The endpoint was defined as the combined outcome of all-cause mortality, right heart failure, and rehospitalization due to disease progression. During a mean follow-up of 17.2 ± 9.9 months, 23 patients (35%) reached the endpoint. Compared with patients with RA reservoir strain (RASr) ≥33.45%, patients with RASr < 33.45% had more adverse long-term outcomes (log rank p < .0001). RASr was independently associated with adverse clinical outcomes according to multivariate analysis (p = .010). CONCLUSION: Our data suggest that RA function has prognostic value for SLE-PAH patients, and strain analysis revealed that the worse the RA function is, the worse the prognosis.

Mir-150-5p distinguishes acute pulmonary embolism, predicts the occurrence of pulmonary arterial hypertension, and regulates ox-LDL-induced endothelial cell injury.

BACKGROUND: Acute pulmonary embolism (APE) is a major type of venous thromboembolism (VTE) with a high risk of mortality and disability. There is a lack of biomarkers for APE to indicate deteriorating development and predict adverse outcomes. This study evaluated the significance of miR-150-5p in APE aiming to explore a novel potential biomarker for APE. METHODS: The study enrolled APE (n = 137) and deep wein thrombosis (DVT, n = 67) patients and collected plasma samples from all study subjects. The expression of miR-150-5p was analyzed by PCR and its significance in screening APE and pulmonary arterial hypertension (PAH) was assessed by receiver operating curve (ROC) and logistic analyses. The study established oxidized low-density lipoprotein (ox-LDL)-induced human venous endothelial cells (HUVECs). Through cell transfection combined with cell counting kit-8 (CCK8), flow cytometry, and enzyme-linked immunosorbent assay (ELISA), the effect of miR-150-5p on ox-LDL-induced HUVEC injury was evaluated. RESULTS: Significant downregulation of miR-150-5p was observed in the plasma of APE patients compared with DVT patients (P < 0.0001). The plasma miR-150-5p levels in APE patients occurred PAH was much lower than in patients without PAH (P < 0.0001). Reducing miR-150-5p distinguished APE patients from DVT patients (AUC = 0.912) and was identified as a risk factor for the occurrence of PAH in APE patients (OR = 0.385, P = 0.010). In HUVECs, oxidized low-density lipoprotein (ox-LDL) caused inhibited cell proliferation, enhanced apoptosis, increased pro-inflammatory cytokines, reactive oxygen species (ROS), malondialdehyde (MDA), and decreased superoxide dismutase (SOD). Overexpressing miR-150-5p could promote proliferation, inhibit apoptosis, and alleviate inflammation and oxidative stress of ox-LDL-treated HUVECs. CONCLUSIONS: Downregulated plasma miR-150-5p served as a diagnostic biomarker for APE and predicted the predisposition of PAH in APE patients. Overexpressing miR-150-5p could alleviate ox-LDL-induced endothelial cell injury in HUVECs.

Prognostic Value of Plasma Immunoglobulin G N-Glycome Traits in Pulmonary Arterial Hypertension.

BACKGROUND: B-type natriuretic peptide or N-terminal pro-B-type natriuretic peptide is the only blood biomarker in established risk calculators for pulmonary arterial hypertension (PAH). Profiling systemic-originated plasma immunoglobulin G (IgG) N-glycans, which reflect different components of the pathophysiology of PAH including immune dysregulation and inflammation, may improve PAH risk assessment. OBJECTIVES: This study sought to identify plasma IgG N-glycan biomarkers that predict survival in PAH to improve risk assessment. METHODS: This cohort study examined 622 PAH patients from 2 national centers (Beijing [discovery] cohort: n = 273; Shanghai [validation] cohort: n = 349). Plasma IgG N-glycomes were profiled by a robust mass spectrometry-based method. Prognostic IgG N-glycan traits were identified and validated in the 2 cohorts using Cox regression and Kaplan-Meier survival analyses. The added value of IgG N-glycan traits to previously established risk models was assessed using Harrell C-indexes and survival analysis. RESULTS: Plasma IgG fucosylation was found to predict survival independent of age and sex in the discovery cohort (HR: 0.377; 95% CI: 0.168-0.845; P = 0.018) with confirmation in the validation cohort (HR: 0.445; 95% CI: 0.264-0.751; P = 0.005). IgG fucosylation remained a robust predictor of mortality in combined cohorts after full adjustment and in subgroup analyses. Integrating IgG fucosylation into previously established risk models improved their predictive capacity, marked by an overall elevation in Harrell C-indexes. IgG fucosylation was useful in further stratifying the intermediate-risk patients classified by a previously established model. CONCLUSIONS: Plasma IgG fucosylation informs PAH prognosis independent of established factors, offering additional value for predicting PAH outcomes.

Establishment of a prediction model of pulmonary artery hypertension in patients with hyperthyroidism.

OBJECTIVE: This study aims to assess the tricuspid annular plane systolic excursion (TAPSE)/PASP ratio as a potential indicator for predicting the probability of developing pulmonary arterial hypertension (PAH) in hyperthyroidism patients. A nomogram model will be developed based on our findings, as well as the receiver operating characteristic (ROC) curve. METHODS: The study involved 166 hyperthyroid patients treated at Yijishan Hospital, and the period covered August 2021 to August 2022. Patients were divided into two groups according to pulmonary artery systolic pressure ≥35 mmHg. Univariate and multivariate logistic analyses were performed on the two groups' demographic and laboratory data to identify potential diagnostic markers. These parameters were evaluated using ROC curves to determine their precision in forecasting PAH. The findings were validated by plotting a calibration curve based on a line chart model. RESULTS: In the study, eventually, 80 patients were enrolled: 30 in the PAH group and 50 in the No PAH group. Multipleistic regression analysis predicted the occurrence risk of developing PAH. When paired with other conventional echocardiographic parameters (such as TAPSE, MPI, and SV) and serological markers (such as FT3 and FT4), the developed model demonstrated outstanding predictive performance with an area under the ROC curve of 0.985, a Youden index of 0.971, a sensitivity of 100%, and a specificity of 97.1%. CONCLUSIONS: The nomogram model constructed by combining the TAPSE/PASP ratio with FT3 and FT4 serum markers, as well as conventional ultrasound parameters SV and MPI in hyperthyroidism patients, demonstrates robust discriminatory ability and consistency.

Oroxylin A, a broad­spectrum anticancer agent, relieves monocrotaline­induced pulmonary arterial hypertension by inhibiting the Warburg effect in rats.

Pulmonary arterial hypertension (PAH) is a chronic and fatal disease characterized by pulmonary vascular remodeling, similar to the 'Warburg effect' observed in cancer, which is caused by reprogramming of glucose metabolism. Oroxylin A (OA), an active compound derived from Scutellaria baicalensis, which can inhibit glycolytic enzymes [hexokinase 2 (HK2), Lactate dehydrogenase (LDH), and pyruvate dehydrogenase kinase 1 (PDK1) by downregulating aerobic glycolysis to achieve the treatment of liver cancer. To the best of our knowledge, however, the impact of OA on PAH has not been addressed. Consequently, the present study aimed to evaluate the potential protective role and mechanism of OA against PAH induced by monocrotaline (MCT; 55 mg/kg). The mean pulmonary artery pressure (mPAP) was measured using the central venous catheter method; HE and Masson staining were used to observe pulmonary artery remodeling. Non­targeted metabolomics was used to analyze the metabolic pathways and pathway metabolites in MCT­PAH rats. Western Blot analysis was employed to assess the levels of glucose transporter 1 (Glut1), HK2), pyruvate kinase (PK), isocitrate dehydrogenase 2 (IDH2), pyruvate dehydrogenase kinase 1(PDK1), and lactate dehydrogenase (LDH) protein expression in both lung tissue samples from MCT­PAH rats. The results demonstrated that intragastric administration of OA (40 and 80 mg/kg) significantly decreased mPAP from 43.61±1.88 mmHg in PAH model rats to 26.51±1.53 mmHg and relieve pulmonary artery remodeling. Untargeted metabolomic analysis and multivariate analysis indicated abnormal glucose metabolic pattern in PAH model rats, consistent with the Warburg effect. OA administration decreased this effect on the abnormal glucose metabolism. The protein levels of key enzymes involved in glucose metabolism were evaluated by western blotting, which demonstrated that OA could improve aerobic glycolysis and inhibit PAH by decreasing the protein levels of Glut1, HK2, LDH, PDK1 and increasing the protein levels of PK and IDH2. In conclusion, OA decreased MCT­induced PAH in rats by reducing the Warburg effect.

Causal relationship between immune cells and pulmonary arterial hypertension: Mendelian randomization analysis.

Immunity and inflammation in pulmonary arterial hypertension (PAH) has gained more attention. This research aimed to investigate the potential causal connections between 731 immunophenotypes and the likelihood of developing PAH. We obtained immunocyte data and PAH from openly accessible database and used Mendelian randomization (MR) analysis to evaluate the causal association between each immunophenotype and PAH. Various statistical methods were employed: the MR-Egger, weighted median, inverse variance weighted (IVW), simple mode, and weighted mode. In the study of 731 different types of immune cells, it was found that 9 showed a potential positive connection (IVW P < .05) with increased risk of PAH, while 19 had a possible negative link to decreased risk. Following false discovery rate (FDR) adjustment, the analysis using the IVW method demonstrated that 5 immune phenotypes were significantly associated with PAH (FDR < 0.05, OR > 1). Conversely, there was a negative correlation between PAH and 4 immune cell types (FDR < 0.05, OR < 1). Sensitivity analyses suggested the robustness of all MR findings. This research, for the first time, has revealed indicative evidence of a causal link between circulating immune cell phenotypes and PAH through genetic mechanisms. These results underscore the importance of immune cells in the pathogenesis of PAH.

Unraveling the Mfn2-Warburg effect nexus: a therapeutic strategy to combat pulmonary arterial hypertension arising from catch-up growth after IUGR.

BACKGROUND: The interplay between intrauterine and early postnatal environments has been associated with an increased risk of cardiovascular diseases in adulthood, including pulmonary arterial hypertension (PAH). While emerging evidence highlights the crucial role of mitochondrial pathology in PAH, the specific mechanisms driving fetal-originated PAH remain elusive. METHODS AND RESULTS: To elucidate the role of mitochondrial dynamics in the pathogenesis of fetal-originated PAH, we established a rat model of postnatal catch-up growth following intrauterine growth restriction (IUGR) to induce pulmonary arterial hypertension (PAH). RNA-seq analysis of pulmonary artery samples from the rats revealed dysregulated mitochondrial metabolic genes and pathways associated with increased pulmonary arterial pressure and pulmonary arterial remodeling in the RC group (postnatal catch-up growth following IUGR). In vitro experiments using pulmonary arterial smooth muscle cells (PASMCs) from the RC group demonstrated elevated proliferation, migration, and impaired mitochondrial functions. Notably, reduced expression of Mitofusion 2 (Mfn2), a mitochondrial outer membrane protein involved in mitochondrial fusion, was observed in the RC group. Reconstitution of Mfn2 resulted in enhanced mitochondrial fusion and improved mitochondrial functions in PASMCs of RC group, effectively reversing the Warburg effect. Importantly, Mfn2 reconstitution alleviated the PAH phenotype in the RC group rats. CONCLUSIONS: Imbalanced mitochondrial dynamics, characterized by reduced Mfn2 expression, plays a critical role in the development of fetal-originated PAH following postnatal catch-up growth after IUGR. Mfn2 emerges as a promising therapeutic strategy for managing IUGR-catch-up growth induced PAH.

Severe pulmonary arterial hypertension in congenital sideroblastic anemia from PUS1 mutation - a case report.

BACKGROUND: Myopathy, lactic acidosis and inherited sideroblastic anemia (MLASA) are a group of rare intriguing disorders with wider pathophysiological implications. One of the causes of MLASA is the mutation in PUS1 gene that encodes for pseudouridine synthase. This PUS1 mutation results in MLASA in which anemia and myopathy predominate. Severe pulmonary arterial hypertension has not been previously reported in patients with PUS1 gene mutation. CASE REPORT: A 17 year old girl with congenital sideroblastic anemia presented with worsening of breathlessness. Severe pulmonary artery hypertension was documented on investigations. A homozygous variant in exon 3 of gene PUS1,( chromosome 12:g.131932301 C > T c.430 C > T) was found on sanger sequencing. CONCLUSION: We document severe pulmonary arterial hypertension in a patient of congenital sideroblastic anemia from PUS1 gene. We hypothesis that cross talk with TGFb pathways might occur in PUS1 mutation, and that might cause severe PAH. This observation might have therapeutic implications.

[Research progress of right ventricular strain imaging evaluation technology in pulmonary arterial hypertension]. / å³å¿ƒå®¤åº”å˜å½±åƒè¯„ä¼°æŠ€æœ¯åœ¨è‚ºåŠ¨è„‰é«˜åŽ‹ä¸­çš„ç ”ç©¶è¿›å±•.

Pulmonary arterial hypertension (PAH) has a subtle onset, rapid progression, and high mortality rate. Imaging evaluation is an important diagnostic and follow-up method for PAH patients. Right ventricular (RV) strain evaluation can identify early changes in RV function and predict the prognosis. Currently, various methods such as tissue Doppler imaging, velocity vector imaging, speckle tracking imaging, and cardiac magnetic resonance imaging can be used to evaluate RV strain in PAH patients. This article aims to summarize the research progress of RV strain imaging evaluation technology in PAH patients, in order to provide a basis for clinical diagnosis and follow-up of PAH patients.

Salidroside enhances NO bioavailability and modulates arginine metabolism to alleviate pulmonary arterial hypertension.

BACKGROUND: Salidroside (SAL), derived from Rhodiola, shows protective effects in pulmonary arterial hypertension (PAH) models, but its mechanisms are not fully elucidated. OBJECTIVES: Investigate the therapeutic effects and the mechanism of SAL on PAH. METHODS: Monocrotaline was used to establish a PAH rat model. SAL's impact on oxidative stress and inflammatory responses in lung tissues was analyzed using immunohistochemistry, ELISA, and Western blot. Untargeted metabolomics explored SAL's metabolic regulatory mechanisms. RESULTS: SAL significantly reduced mean pulmonary artery pressure, right ventricular hypertrophy, collagen deposition, and fibrosis in the PAH rats. It enhanced antioxidant enzyme levels, reduced inflammatory cytokines, and improved NO bioavailability by upregulating endothelial nitric oxide synthase (eNOS), soluble guanylate cyclase (sGC), cyclic guanosine monophosphate (cGMP), and protein kinase G (PKG) and decreases the expression of endothelin-1 (ET-1). Metabolomics indicated SAL restored metabolic balance in PAH rats, particularly in arginine metabolism. CONCLUSIONS: SAL alleviates PAH by modulating arginine metabolism, enhancing NO synthesis, and improving pulmonary vascular remodeling.

Safflower Alleviates Pulmonary Arterial Hypertension by Inactivating NLRP3: A Combined Approach of Network Pharmacology and Experimental Verification.

INTRODUCTION: Traditional Chinese medicinal plant, safflower, shows effective for treating pulmonary arterial hypertension (PAH), yet the underlying mechanisms remain largely unexplored. This study is aimed at exploring the potential molecular mechanisms of safflower in the treatment of PAH. METHODS: Network pharmacology approach and molecular docking were applied to identify the core active compounds, therapeutic targets, and potential signaling pathways of safflower against PAH. Meanwhile, high-performance liquid chromatography (HPLC) assay was performed to determine the core compounds from safflower. Further, the mechanism of action of safflower on PAH was verified by in vivo and in vitro experiments. RESULTS: A total of 15 active compounds and 177 targets were screened from safflower against PAH. Enrichment analysis indicated that these therapeutic targets were mainly involved in multiple key pathways, such as TNF signaling pathway and Th17 cell differentiation. Notably, molecular docking revealed that quercetin (core compound in safflower) displayed highest binding capacity with NLRP3. In vivo, safflower exerted therapeutic effects on PAH by inhibiting right ventricular hypertrophy, inflammatory factor release, and pulmonary vascular remodeling. Mechanistically, it significantly reduced the expression of proangiogenesis-related factors (MMP-2, MMP-9, Collagen 1, and Collagen 3) and NLRP3 inflammasome components (NLRP3, ASC, and Caspase-1) in PAH model. Similarly, these results were observed in vitro. Besides, we further confirmed that NLRP3 inhibitor had the same therapeutic effect as safflower in vitro. CONCLUSION: Our findings suggest that safflower mitigates PAH primarily by inhibiting NLRP3 inflammasome activation. This provides novel insights into the potential use of safflower as an alternative therapeutic approach for PAH.

The Co-pathogenic Target Gene CNTN1 Involved in Coronary Artery Disease and Pulmonary Arterial Hypertension Has Potential for Diagnosis of Coronary Artery Disease.

BACKGROUND: We aimed to find a gene for coronary artery disease (CAD) early diagnosis by detecting co-pathogenic target gene involved in CAD and pulmonary arterial hypertension (PAH). Methods: Datasets were obtained from the Gene Expression Omnibus (GEO) database, including GSE113079, GSE113439, and GSE12288, to investigate gene expression patterns in cardiovascular diseases. Weighted Gene Co-expression Network Analysis (WGCNA) was performed to identify gene modules associated with clinical traits. Differential gene expression analysis and functional enrichment analysis were carried out. Protein-protein interaction (PPI) networks were constructed. JASPAR database and FIMO tool were utilized to predict transcription factor (TF) binding sites. Results: Fifteen key genes were identified in CAD and PAH, with CNTN1 being prioritized for further investigation due to its high connectivity degree. Upstream regulation analysis identified potential TFs (DRGX, HOXD3, and RAX) and 7 miRNAs targeting CNTN1. The expression profile of CNTN1 was significantly upregulated in CAD samples, and ROC analysis indicated potential diagnostic value for CAD. CMap database analysis predicted potential targeted drugs for CAD. Conclusion: CNTN1 was detected as a co-pathogenetic gene for CAD and PAH. It is highly expressed in CAD patients and has potential value for CAD diagnosis. CNTN1 is potentially regulated by 3 TFs and 7 miRNAs.

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.

Cellular senescence in the pathogenesis of pulmonary arterial hypertension: the good, the bad and the uncertain.

Senescence refers to a cellular state marked by irreversible cell cycle arrest and the secretion of pro-inflammatory and tissue-remodeling factors. The senescence associated secretory phenotype (SASP) impacts the tissue microenvironment and provides cues for the immune system to eliminate senescent cells (SCs). Cellular senescence has a dual nature; it can be beneficial during embryonic development, tissue repair, and tumor suppression, but it can also be detrimental in the context of chronic stress, persistent tissue injury, together with an impairment in SC clearance. Recently, the accumulation of SCs has been implicated in the pathogenesis of pulmonary arterial hypertension (PAH), a progressive condition affecting the pre-capillary pulmonary arterial bed. PAH is characterized by endothelial cell (EC) injury, inflammation, and proliferative arterial remodeling, which leads to right heart failure and premature mortality. While vasodilator therapies can improve symptoms, there are currently no approved treatments capable of reversing the obliterative arterial remodeling. Ongoing endothelial injury and dysfunction is central to the development of PAH, perpetuated by hemodynamic perturbation leading to pathological intimal shear stress. The precise role of senescent ECs in PAH remains unclear. Cellular senescence may facilitate endothelial repair, particularly in the early stages of disease. However, in more advanced disease the accumulation of senescent ECs may promote vascular inflammation and occlusive arterial remodeling. In this review, we will examine the evidence that supports a role of endothelial cell senescence to the pathogenesis of PAH. Furthermore, we will compare and discuss the apparent contradictory outcomes with the use of interventions targeting cellular senescence in the context of experimental models of pulmonary hypertension. Finally, we will attempt to propose a framework for the understanding of the complex interplay between EC injury, senescence, inflammation and arterial remodeling, which can guide further research in this area and the development of effective therapeutic strategies.

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.

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.