Pulmonary Hypertension Research Articles

Background: First identified by Sharp et al. in 1972, Mixed Connective Tissue Disease (MCTD) is an autoimmune overlap syndrome that is typified by anti-U1RNP antibody positivity and symptoms of polymyositis, systemic lupus erythematosus, and systemic sclerosis. Case Presentation: A 39-year-old female presented with fever, limb and small joint pain, exertional dyspnea, bluish discoloration of fingers on cold exposure (Raynaud’s phenomenon), and dysphagia. Examination was unremarkable. Investigations revealed anemia (Hb 8.4 g/dL), thrombocytopenia (0.80 lakhs/cumm), elevated troponin-T (29.11 pg/mL), and CPK (255 IU/L). ECG showed poor R-wave progression with T-wave inversion (V1–V4), and echocardiography revealed dilated right chambers with severe tricuspid regurgitation and pulmonary hypertension. ANA and anti-U1RNP were positive, along with anti-Scl-70; skin biopsy showed sclerosis. Discussion: The patient fulfilled both Alarcón-Segovia and Kasukawa diagnostic criteria for MCTD based on serology and clinical findings. Cardiac and pulmonary involvement underscored the disease’s systemic nature. Conclusion: Early recognition of overlapping autoimmune features and serological markers is vital for timely diagnosis and management of MCTD to prevent life-threatening complications.

Antibody-drug conjugates are proving to be highly effective in oncology, yet their real-world respiratory safety profile remains largely unknown. This study sought to characterize drug-linked respiratory disorders and identify safety signals. We performed a descriptive analysis with expert review of respiratory adverse drug reactions related to antibody-drug conjugates from the French pharmacovigilance database. We also conducted disproportionality analyses for interstitial lung disease, pulmonary arterial hypertension, and pleural disorder using VigiBase®. Among the 71 patients included in the descriptive study, 56 (78.9%) were women, and the median age was 60 years. Most (71.8%) were treated for breast cancer. Fifty-nine patients (83.1%) developed antibody-drug conjugate-related interstitial lung disease, primarily after trastuzumab deruxtecan. Nine patients (12.7%) developed pulmonary arterial hypertension and three (4.2%) contracted pleural disorders, mainly after trastuzumab emtansine. The median time to onset varied by clinical feature, with 1 month for pleural disorder, 4 months for interstitial lung disease, and 45 months for pulmonary arterial hypertension. The disproportionality analysis showed a significant signal for interstitial lung disease with brentuximab vedotin, polatuzumab vedotin, trastuzumab emtansine, and trastuzumab deruxtecan. Only trastuzumab emtansine had a significant signal for pulmonary arterial hypertension. All antibody-drug conjugates, except belantamab mafodotin and enfortumab vedotin, were associated with a significant signal for pleural disorders. Our study highlights the risk of interstitial lung disease with these drugs in real-world settings and identified pulmonary arterial hypertension and pleural disorders as additional safety signals. Further research is needed to confirm these findings in population-based studies and to identify antibody-drug conjugates and patient-related risk factors.

Hypoxic pulmonary hypertension (HPH) serves as a crucial link in the pathogenesis of chronic high-altitude diseases and chronic obstructive pulmonary disease (COPD), and ultimately may lead to right heart failure. Hypoxia triggers immune responses and inflammatory processes, which contribute to vascular remodeling and elevated pulmonary artery pressure. NLRX1, a member of the Nod-like receptor family, plays a significant regulatory role in immunity, antioxidation, and apoptosis. However, its role in the occurrence and development of HPH remains unknown. Wild type (WT) C57BL/6 mice and NLRX1 knockout (NLRX1-/-) Mice were subjected to intermittent chronic hypoxia for 6 weeks to establish a hypoxic pulmonary hypertension model that is similar to the moderate pulmonary hypertension (PH) induced by hypoxia in humans. Subsequently, data on hemodynamics and pulmonary pathomorphology were collected. Additionally, bone marrow derived macrophages (BMDMs) were cultured to determine the effects of up-regulating and down-regulating NLRX1 on cell function under hypoxia exposure. Western blotting or reverse transcription polymerase chain reaction (RT-PCR) was utilized to detect changes in inflammation factors and oxidative stress-related indicators in rat lung tissue and cultured BMDMs. Hypoxia downregulates the expression of NLRX1 in the lung tissues of mice and bone marrow-derived macrophages (BMDM). Chronic hypoxia significantly increases right ventricular systolic pressure (RVSP), the ratio of right ventricle weight to left ventricle plus septum weight (RV/LV + S), and the medial width of pulmonary arterioles in NLRX1-knockout (NLRX1-/-) mice. NLRX1 mediates the hemodynamic response and right ventricular hypertrophy in mice with hypoxic pulmonary hypertension. The deficiency of NLRX1 upregulates inflammatory mediators by activating nuclear factor-κB (NF-κB) and simultaneously promotes oxidative stress and the activation of nuclear factor E2-related factor 2 (Nrf2). The activator NX-13 of NLRX1 can reduce the production of inflammatory cytokines in BMDMs stimulated by hypoxia and mitigate oxidative stress. NLRX1 may suppress hypoxia-induced lung inflammation and alleviate hypoxia-induced pulmonary hypertension through its anti-inflammatory and antioxidant properties. Therefore, targeted up-regulation of NLRX1 may offer a new strategy for the treatment of HPH.

Chest wall deformities are considered a risk factor for lung transplantation. A 5-year-old girl with protein surfactant C deficiency, interstitial lung disease, pulmonary hypertension, and pectus excavatum (Haller 5.9) underwent lung transplantation and Nuss bar placement. Correction of her pectus was necessary to accommodate donor lungs. She was discharged after 18 days. We hope this youngest described child who underwent simultaneous transplant and pectus correction with excellent outcomes will lead others to consider concomitant surgeries.

Background/Objectives: Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease, in which multiple genetic and environmental factors may contribute. This study aimed to identify potential genetic determinants in patients with CTEPH and to compare their occurrence to a control group, which included patients with pulmonary embolism who had not developed CTEPH. Methods: Tier 1 and 2 genes related to coagulation, fibrinolysis and platelet disorders—as recommended by the International Society on Thrombosis and Haemostasis—and genes associated with vascular conditions were analyzed in n = 15 patients with CTEPH and n = 17 controls using next-generation sequencing. Non-synonymous, rare variants were collected and interpreted. Results: As expected, no single gene or variant was consistently present among CTEPH patients. Instead, individuals carried different mutations and combinations of variants. We identified several variants that were not found in the control group. Candidate variants were detected in F12, F13A1, F13B, F5, KNG1, SERPIND1, THBD, ADAMTS13, VWF, STIM1, ETV6, THPO, MPL, SERPINA1, ENG, RASA1, ACVRL1, GDF2, NFE2, SOX17 and RNF213. We did not detect exclusive variants in FGA, CPB2, and BMPR2 although they were suggested as candidates in previous studies. Elevated factor VIII and von Willebrand factor in CTEPH could not be explained by mutations in VWF and F8. Conclusions: Our study supports the hypothesis of heterogeneous genetic background in CTEPH, involving multiple pathways such as coagulation, altered fibrinolysis and impaired angiogenesis. These results provide a basis for more detailed investigations into specific genes and variants potentially associated with CTEPH in larger cohorts.

Background Pulmonary hypertension (PH) is a complex and progressive disease characterized by elevated pulmonary vascular resistance. Inflammation plays an important role in the pathogenesis of PH. Interferons (IFNs) are key immune cytokines that regulate cellular responses to various stimuli. This study aimed to investigate the association between IFN levels and the risk and prognosis of PH. Methods A cohort of 875 PH patients and 182 matched controls were included in this study. Logistic regression models and receiver operating characteristic (ROC) curves were applied to evaluate the association between IFN levels and PH risk. Correlations between variables were assessed using Spearman's rank correlation coefficient (r ). Cox proportional hazards regression and Kaplan-Meier survival curves were used to assess the prognostic value of IFNs levels. The predictive performance of prognostic models was assessed using ROC analysis and decision curve analysis and a nomogram was constructed to estimate individual overall survival probabilities. Results Both IFN-α and IFN-γ levels were significantly elevated in PH patients compared with controls ( P < 0.05 for both), with IFN-α showing stronger predictive value across multiple PH subgroups ( P < 0.05 for all), particularly in patients with Group 4 PH and idiopathic pulmonary arterial hypertension (IPAH). In Cox regression models, IFN-α was significantly associated with lower survival in PH patients (HR: 1.120, 95% CI: 1.001-1.253, P = 0.048). Kaplan-Meier analysis demonstrated that patients with IFN-α > 2.131 pg/mL had significantly lower 5-year cumulative survival rate of 60.1%, compared with 81.2% for those with IFN-α ≤ 2.131 pg/mL (Log Rank P < 0.001). A prognostic model combining IFN-α with traditional clinical markers, such as WHO-FC, 6-MWD, and NT-proBNP, improved predictive accuracy, with IFN-α contributing additional clinical net benefit in risk stratification. Conclusions These findings suggest that plasma IFN-α may serve as a valuable biomarker for both predicting PH risk and assessing prognosis.

Pulmonary arterial hypertension (PAH) is a subtype of pulmonary hypertension (PH), characterized by pulmonary arterial remodeling. This disease frequently progresses to right heart failure and can result in patient mortality. Research at the cellular and molecular level is gradually revealing the mechanism underlying the development of pulmonary arterial hypertension, providing new avenues for treatment by identifying potential therapeutic targets. Contact between the endoplasmic reticulum and mitochondria has been recognized for several decades. And an increasing number of laboratory and clinical studies are beginning to elucidate the relationship between PAH and the interplay involving mitochondria and the endoplasmic reticulum. In this review, we first introduce the basic normal biological functions and processes of MAM-based mitochondrial-endoplasmic reticulum interactions. We then discuss how the dysfunction contributes to pulmonary arterial hypertension (PAH), focusing on three key aspects, mitochondrial dynamics, calcium homeostasis, and endoplasmic reticulum stress. Clarifying these issues may provide important insights for therapeutic interventions in PAH.

Background Pulmonary arterial hypertension (PAH) is a progressive disorder characterized by pulmonary vascular remodeling and mitochondrial dysfunction. Recent studies have implicated impaired mitophagy in the pathogenesis of PAH; however, the underlying mechanisms and associated biomarkers remain insufficiently defined. This study used an integrative approach, incorporating bulk transcriptomic profiling, single-cell RNA sequencing (scRNA-seq), machine learning algorithms, and experimental validation to explore the relationship between mitophagy and PAH. Methods Differentially expressed genes were extracted from publicly available microarray datasets and intersected with mitophagy-related genes curated from the MitoCarta 3.0 database. Weighted gene co-expression network analysis, along with five distinct machine learning models, identified five candidate mitophagy-associated biomarkers: RRAS , BECN1 , MFN1 , HIF1A , and TAX1BP1 . These genes demonstrated high diagnostic performance (area under the curve >0.9) across both training and validation cohorts. Immune cell deconvolution analysis indicated a marked increase in M1 macrophage infiltration in lung tissue from individuals with PAH. The scRNA-seq further localized the expression of these biomarkers predominantly to monocyte/macrophage populations and indicated distinct pseudotemporal expression trajectories during macrophage differentiation. Expression and co-localization of the identified biomarkers with autophagy and inflammation markers were subsequently validated using quantitative PCR, western blotting, and immunofluorescence in a monocrotaline-induced PAH rat model. Results and Conclusion The findings underscore the involvement of mitophagy in the pathobiology of PAH and identify five macrophage-associated biomarkers with strong diagnostic potential. These results may inform future strategies aimed at early detection and targeted therapeutic interventions in PAH.

Background: Pulmonary hypertension is common in left-sided heart valve disease, with historical studies reporting mortality rates up to 31% in severe cases undergoing mitral valve surgery. This study evaluates the impact of severe pulmonary hypertension on outcomes of mechanical mitral valve replacement with posterior leaflet preservation by comparing results with patients having mild-to-moderate pulmonary hypertension. Methods: Prospective analysis of 86 patients with mitral valve disease undergoing mechanical valve replacement with posterior leaflet preservation from March 2015 to September 2016 was conducted. Patients were stratified by pulmonary artery pressure: severe (≥60 mmHg, n = 19) versus mild–moderate (35–59 mmHg, n = 67). Primary outcomes included mortality, complications, and functional recovery at 1, 6, and 12 months. Results: The cohort included 67 patients (77.9%) with mild–moderate pulmonary hypertension and 19 patients (22.1%) with severe pulmonary hypertension. Severe pulmonary hypertension patients demonstrated higher NYHA functional class (73.7% class III vs. 46.2%, p = 0.03), larger left atrial diameter (56.3 ± 9.8 vs. 49.5 ± 6.7 mm, p = 0.01), and higher mean pressure gradients (14.4 ± 5.3 vs. 11.3 ± 5.0 mmHg, p = 0.025). Mortality was 5.3% in the severe group versus 0% in the mild–moderate group (p = 0.331). Patients with severe pulmonary hypertension required longer ICU stays (6.3 ± 3.7 vs. 4.7 ± 2.2 days, p = 0.024) but showed no significant differences in ventilation time, reoperation rates, or major complications. At the 12-month follow-up, both groups achieved equivalent outcomes in pulmonary artery pressures, left ventricular function, and cardiac dimensions. Conclusion: In this study with a relatively small sample size, severe pulmonary hypertension was associated with significantly longer intensive care unit stay but not with higher mortality compared to mild–moderate pulmonary hypertension, with both groups attaining comparable functional and hemodynamic parameters at 12 months after mechanical mitral valve replacement with posterior leaflet preservation.

The impact of menopausal hormone therapy (HT), and its timing on cardiovascular disease (CVD) remains controversial in women. Examine the association of HT with incident CVD in women veterans (WV). Veterans Health Administration (VHA) electronic records were used to identify WV aged ≥45 years who engaged with VHA from 1/1/2000-12/31/2017. HT was defined as any oral or transdermal estrogen-containing product or combined estrogen-progestin. Incident CVD was defined as new-onset ischemic heart disease (IHD), stroke, heart failure (HF), atrial fibrillation/flutter (AF), aortic stenosis (AS), pulmonary hypertension (PHTN), venous thromboembolism (VTE), peripheral arterial disease (PAD). Propensity score matching was used to match WV with and without HT on demographics, CVD risk factors, mental health conditions, and cardiovascular medication use. Cox proportional hazards models were used to estimate hazard ratios. Stratified analyses were conducted across distinct age categories. A total of 241,943 WV met the inclusion criteria, including 9,295 with HT. After 1:2 propensity score matching the HT cohort had significantly higher rates of CVD compared to non-HT cohort (22.4% versus 11.7%, p < 0.001), and all-cause mortality (8.0% versus 5.2%, p < 0.001). In the Cox proportional hazards regression model, HT was independently associated with a greater risk of CVD (HR=1.74, 95% CI 1.63-1.85), Death (HR=1.25 95% CI 1.13-1.39), and IHD, stroke, HF, AF, AS, PHTN, PAD and VTE. Our results suggest that menopausal HT is associated with increased risk of a broad range of CVD and death in WV 45 years and older.

Roles of the Altitude-Adapted Immune Microenvironment in Pulmonary Vascular Remodeling in High-Altitude Pulmonary Hypertension: A Review

Background: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by pulmonary arterial remodelling, leading to right ventricular failure. Accumulating evidence shows the importance of inflammation in the pathogenesis of PAH. Regnase-1 is a ribonuclease essential in limiting inflammation by degrading messenger RNAs involved in immune responses, such as interleukin-6 (IL-6) and IL-1β. This occurs through recognition of stem-loop structures in the 3′ untranslated regions of target mRNAs by Regnase-1. We previously reported that Regnase-1 mRNA expression was reduced in peripheral blood mononuclear cells of PAH patients and that its expression was inversely correlated with the severity of the disease. In addition, myeloid-specific deletion of Regnase-1 in mice led to the spontaneous development of severe PAH, accompanied by enhanced accumulation of inflammatory cells in the lungs (Circulation. 2022, 146(13):1006). We hypothesized that inducing increased expression of Regnase-1 could ameliorate the pathology of pulmonary hypertension (PH). Methods: We designed antisense phosphoramidate morpholino oligonucleotides (MOs) that bind to the stem-loop structure within the 3′ UTR of Regnase-1 mRNA. We previously demonstrated that the designed MOs suppress Regnase-1 self-degradation in mice and human cells (Sci Transl Med. 2022,14(644):eabo2137). We developed additional MOs that specifically bind to Regnase-1 mRNA in rats, inhibiting self-degradation by Regnase-1. We then examined the effects of these Regnase-1-targeted MOs on PH pathology in both a hypoxia-induced PH mouse model and a monocrotaline-induced PH rat model. Results: Intratracheal administration of Regnase-1-targeting MOs improved PH pathology in the hypoxia-induced PH mouse and monocrotaline-induced PH rat models. We confirmed that Regnase-1-targeting MO administration suppressed the decline in Regnase-1 mRNA expression in the lungs of each PH model. Regnase-1-targeting MO administration significantly reduced the increase in inflammatory cytokine expression, particularly IL-6 mRNA expression, in the lungs. Conclusions: Intratracheal administration of Regnase-1-targeting MOs increased Regnase-1 mRNA expression and suppressed inflammation in the lungs of PH model animals, thereby improving PH pathology. Disrupting the Regnase-1 self-regulation pathway with MOs might become a potential therapeutic strategy to enhance Regnase-1 abundance and suppress inflammation in PH patients.

Introduction: Pulmonary hypertension (PH) is a life-threatening, progressive disease with non-specific symptoms, often leading to delayed diagnosis. Early identification of World Health Organization Group 1 (Pulmonary Arterial Hypertension, PAH) and Group 4 (Chronic Thromboembolic Pulmonary Hypertension, CTEPH) is essential, as effective therapies can improve outcomes. Hypothesis: An electrocardiogram-based AI algorithm for PH detection (ECG-AI PH) may enable earlier diagnosis and reduce healthcare utilization, including hospitalizations and procedures. Methods: Retrospective analysis used a de-identified data platform of &gt;7M clinical records from a multistate integrated health system. Adult precapillary PH patients (mPAP &gt;20 mmHg, PVR &gt;2 WU, PCWP ≤15 mmHg) were identified as PAH or CTEPH based on ICD codes, use of approved therapies, or surgical interventions (for CTEPH) between 2002 and 2024. ECG-AI PH was applied to ECGs within 30 days of diagnostic right heart catheterization, using a 5:1 randomly sampled PH-negative control cohort. Training set patients were excluded. Clinical event frequency was compared between two intervals: from first possible PH symptom (dyspnea, syncope, chest pain, fatigue, lower limb swelling) to diagnosis, and from symptom onset to first positive ECG-AI PH prediction. Results: A total of 1882 PAH and 359 CTEPH patients met inclusion criteria. Of these, 1340 PAH and 258 CTEPH patients had symptom codes prior to diagnosis. Both groups showed prolonged intervals from symptom onset to diagnosis, with multiple diagnostic procedures and hospitalizations (Figure). ECG-AI PH performance evaluation on the test set included 647 PAH and 152 CTEPH patients. ECG-AI PH achieved AUCs of 0.90 and 0.89 for PAH and CTEPH, sensitivities of 80.3% and 76.8%, and specificities of 83.4% and 82.4%. Among those tested, 576 PAH and 95 CTEPH patients had a positive ECG-AI PH prediction after symptom onset but before diagnosis. Compared to the current patient journey, the interval between initial symptoms and a positive output from ECG-AI PH was shorter and had fewer diagnostic tests/visits. Conclusion: ECG-AI PH demonstrated strong performance in detecting PAH and CTEPH. It may reduce diagnostic delays, support earlier PH-focused screening (e.g., echocardiograms evaluating the right heart), enable earlier intervention, and reduce pre-diagnosis healthcare burden, benefitting both patient outcomes and healthcare system efficiency.

Background: Cardiac involvement is a major contributor to morbidity and mortality in systemic sclerosis (SSc), yet valvular heart disease remains underrecognized. Fibrotic and vascular remodeling in SSc may predispose to valve lesions, which can exacerbate right or left heart failure, particularly in the presence of pulmonary hypertension (PH). Emerging data suggest that valvular dysfunction, especially regurgitant lesions, is associated with more advanced cardiopulmonary disease and may serve as a marker of increased mortality risk. We aimed to characterize the burden and distribution of valvular disease across SSc subtypes and PH phenotypes. Methods: We analyzed a cohort of SSc patients from Johns Hopkins Medicine who were referred for transthoracic echocardiogram for evaluation of pulmonary vascular disease between September 2003 and April 2025. Demographic and clinical metrics, invasive hemodynamics, and echocardiographic parameters were analyzed. Patients were classified into limited cutaneous SSc, diffuse cutaneous SSc, or SSc with overlap of another mixed connective tissue disease (MCTD). PH subtype was determined based on invasive hemodynamics and World Health Organization classification. Disease duration was calculated from date of Raynaud’s onset. Comparative analyses were conducted using ANOVA, Chi-Squared tests, and ordered logistic regression. Results: Our cohort consisted of 211 SSc patients, mean age 64 ± 13 years, 82% female, 71% white, 52% limited SSc subtype, 74% with PH, Table 1 . Patients with interstitial lung disease associated PH or pulmonary arterial hypertension displayed significantly higher odds for more severe tricuspid regurgitation (TR) compared to those without PH (p = 0.001), Table 2 . Additionally, individuals with diffuse SSc showed a higher prevalence of advanced TR compared to those with limited SSc (p = 0.037) and MCTD (p = 0.019). Among patients with MCTD, extensive aortic regurgitation was more prevalent than in limited SSc (p = 0.018), and the occurrence of higher-grade mitral regurgitation was significantly greater compared to both limited (p = 0.021) and diffuse SSc (p = 0.037). Conclusion: Valvular regurgitation is a prevalent and clinically relevant manifestation in SSc, particularly among patients with PH and diffuse SSc or MCTD. These findings underscore the importance of routine echocardiographic surveillance to detect and manage valvular disease early in the course of SSc-related cardiopulmonary involvement.

Background: Pulmonary arterial hypertension (PAH) is a progressive and fatal disease characterized by pulmonary vascular remodeling, increased right ventricular pressure, and eventual heart failure. Elevated levels of oxidized lipid metabolites especially hydroxyeicosatetraenoic acids (HETEs) have been observed in both human patients and animal models, implicating these lipids in the disease’s pathogenesis. We previously demonstrated that dietary supplementation with 15-HETE for 3 weeks is sufficient to induce pulmonary hypertension (PH) in C57BL6/J. However, the molecular mechanisms remain poorly understood. During our investigations, we discovered that dietary 15-HETE increases systemic oxylipin levels of not only 15HETE but also other HETEs (including 5-, 12-), like PAH patients. We therefore hypothesized that 15-HETE promotes PH through an initial lipoxygenase (LOX)-mediated oxylipin amplification, which in turn drives metabolic and immune alterations in the gut and contribute to progression of PH. Methods: PH development was assessed by pulmonary arterial acceleration time (PAAT) and right ventricular systolic pressure (RVSP). LOX involvement was tested by blocking total LOX activity, treating 12/15-LOX-deficient mice with a 5-LOX inhibitor (zileuton). Plasma lipid profiles were analyzed mass spectrometry. Cytokine levels were measured by multiplex immunoassay. Flow cytometry was used to evaluate gut immune populations. Results: 15-HETE alone, 5-HETE alone or combined 5-HETE and 12-HETE supplementation induced PH, reflected by significantly decreased PAAT and elevated RVSP. Lipidomics analysis revealed increased oxilipins in 15-HETE treated mice. Elevation in plasma inflammatory cytokines (including eotaxin, G-CSF, IL-15, and MCP-1) and shifts in gut immune cells (increased Type 1 macrophages and decreased neutrophils) were observed in 15-HETE treated mice, suggesting an inflammatory response initiated in the gut. Finally, 12/15-LOX deficiency combined with zileuton treatment not only reduced intestinal 5-, 12-, 15-HETE levels but also prevented 15-HETE induced PH suggesting that 15-HETE mediated oxylipin amplification is causal in the development of PH in mice treated with 15-HETE. Conclusions: Our findings suggest that the gut appears to play a previously underappreciated role in the development of PH, highlighting the potential of targeting LOX pathways and gut–lung interactions in the treatment of PAH.

Chronic exertional dyspnea has been documented in US Veterans after deployment to Iraq and Afghanistan with reported environmental inhalation exposures. We studied whether continued exertional dyspnea in this patient population is associated with pulmonary vascular disease (PVD) and pulmonary hypertension (PH). We performed detailed histomorphometry of pulmonary vasculature in 52 Veterans with biopsy-proven post-deployment respiratory syndrome (PDRS). Lung tissue specimens obtained from 15 non-diseased (ND) subjects, 13 end-stage patients with pulmonary arterial hypertension (PAH, Group 1 PH) and 8 patients with pulmonary hypertension due to left heart failure (LHF, Group 2 PH) were used as negative and positive controls, respectively. Then, we recruited nine of these Veterans with continued exertional dyspnea to undergo a follow-up clinical evaluation, including symptom questionnaire, pulmonary function testing, surface echocardiography, and right heart catheterization (RHC). Morphometric evaluation of pulmonary vasculature showed striking pathological changes in all patient groups. In bronchovascular bundle pulmonary arteries (BVB arteries), increased intima and media thicknesses were identified. Observed vascular pathology was not limited to BVBs but also extended to distal compartments, affecting intra-acinar (IA) arteries and veins, which are located within alveolar tissue and not associated with distal bronchioles. We found that the pathological changes in IA arteries in PDRS are less severe than in PAH and similar to LHF. Pathological remodeling of IA veins was characterized by similar fractional thicknesses of intima and adventitia in PDRS and PAH but was much less severe compared to LHF. In comparison to PAH and LHF patients, Veterans with PDRS had more prominent fibrosis (collagen deposition) at all generations of pulmonary vessels analyzed. Of the nine Veterans involved in clinical follow-up study, six had evidence of post-capillary PH on RHC at rest and one had PH at exercise. In contrast to patients with LHF, none of the Veterans who underwent RHC had evidence of systolic or diastolic dysfunction on surface echocardiography. Although further investigations are needed, these findings may suggest that Veterans with undiagnosed exertional dyspnea can develop previously unrecognized toxicant-mediated form of PH, which is post-capillary, may occur in the absence of left heart dysfunction and has unique vascular pathologic features.

Background: Right ventricular failure (RVF) is the strongest risk factor for mortality in pulmonary arterial hypertension (PAH). RVF is deadly because it leads to multi-organ dysfunction. Recent studies show that hepatic dysfunction correlates with RVF and is an important predictor of outcomes in PAH. However, the cell-specific impacts of PAH-mediated RVF in human livers are unexplored. Methods: Nuclei were isolated from autopsy-derived liver tissue from four healthy control and five PAH patients. Single-nucleus RNA sequencing (snRNAseq) was performed by 10X Genomics and analyzed in RStudio using Seurat. Publicly available snRNAseq datasets of human liver tissue from non-alcoholic steatohepatitis (NASH) and Fontan-associated liver disease (FALD) were compared to PAH. Results: 57,057 control and 71,792 PAH hepatic nuclei were analyzed via snRNAseq. Hepatocyte relative abundances were uniquely increased in PAH. Moreover, PAH induced a pro-proliferative, Warburg-like metabolic phenotype in hepatocytes, a finding mirrored by PAH endothelial cells. NASH hepatocytes and endothelial cells were characterized by a hypermetabolic phenotype, whereas FALD hepatocytes and endothelial cells only displayed suppressed oxidative phosphorylation without alterations in glycolysis. Derangements in the cytochrome P450 oxidation system were present in PAH and NASH hepatocytes, but not FALD. Pro-inflammatory signaling was observed in both PAH hepatic stellate cells and macrophage. PAH hepatic stellate cells were characterized by upregulated HIF-1 and PI3K/Akt/mTOR signaling, as opposed to PI3K/Akt/mTOR signaling alone in NASH or the combination of TGF-beta and Wnt signaling in FALD. Complement transcripts were enriched and cell-cell communication was hindered in PAH macrophages. NASH and FALD macrophages had heightened predicted intercellular interactions, with elevated complement and JAK-STAT signaling, respectively. Finally, PAH uniquely modified the expression of vasoactive genes (ENG, FLT1, GDF15) across several cell types, augmented interleukin-6 production in hepatic stellate cells, and suppressed ketone metabolism in hepatocytes. Conclusion: PAH hepatopathy is a distinct cellular and molecular phenomenon as compared to FALD and NASH. These data delineate PAH-specific therapeutic targets and nominate liver-specific alterations that may contribute to the systemic manifestations of PAH.

Background: The cellular heterogeneity and molecular mechanisms underlying human pulmonary arterial hypertension (PAH) remain incompletely characterized. We aimed to construct a comprehensive single-cell lung atlas of human PAH to elucidate shifts in cellular composition and disease-specific gene expression. Methods: Flash-frozen lung tissues were collected from 10 healthy donors and 30 PAH patients, including idiopathic PAH (IPAH), drug/toxin-induced PAH, and PAH secondary to systemic-to-pulmonary shunting, representing diverse sexes, ethnicities, and ages. Fixed lung tissues were processed for single-cell RNA sequencing and single-cell resolution spatial transcriptomics using 10X Genomics Xenium 5K gene panel. We analyzed changes in cell proportions, gene expression, and pathways across disease subtypes, sexes, and age groups. Results: We identified four major cell lineages and 34 distinct clusters. We discovered a novel subtype: COL15A1 + systemic arterial endothelial cells (SAECs) , characterized by co-expression of arterial EC markers and COL15A1 . Spatial transcriptomics analysis and immunostaining confirmed that SAECs localized within plexiform and occlusive vascular lesions in PAH lungs. SAECs were enriched for genes involved in migration, shear stress response, and coagulation. PAH SAECs exhibited strong upregulation of genes linked to angiogenesis, epithelial-mesenchymal transition (EMT), apical surface remodeling, and Wnt/β-catenin signaling. Transcriptional factor prediction showed that SAECs identity was maintained by SOX18, E2F6 and SOX6. Ligand-receptor interaction demonstrated that SAECs produce the most significantly autocrine and paracrine signaling in PAH lungs. Cellular lineage pseudotime analysis revealed SAECs might come from arterial ECs or systemic venous ECs in PAH. Global cell proportion analysis showed consistent PAH-associated increases in SAECs, systemic venous ECs, secondary crest myofibroblasts (SCMF), and alveolar fibroblast 2. Notably, female PAH patients exhibited reduced mast cells, CD8 + T cells, and vascular smooth muscle cells, but enrichment of SAECs, SCMFs, and platelets. EMT emerged as a core upregulated pathway across all major cell types in PAH. Conclusion: Our integrative single-cell atlas of human PAH lungs identifies a previously unrecognized SAECs and provides deep insight into the molecular and cellular landscape of PAH across disease subtypes and sexes.

Background: Dysregulated fibroblasts and macrophages have been implicated in vascular remodeling in pulmonary arterial hypertension (PAH). Macrophages are known to modulate fibroblast activity in fibrotic lung diseases. However, the spatial interactions between fibroblasts and macrophages within the lung tissue context of PAH remain largely unexplored. Hypothesis: High-resolution spatial transcriptomics can reveal cell–cell interactions in PAH. We hypothesize that spatial interactions between macrophages and fibroblasts are increased in PAH lungs and may contribute to vascular remodeling. Approach: Mice with Tie2Cre-mediated deletion of Egln1 (Egln1 Tie2Cre , or CKO) were used, as these animals exhibit spontaneous and severe pulmonary hypertension (PH) with pronounced vascular remodeling. Lung tissues from wild-type (WT) and CKO mice were analyzed using the high-resolution 10x Genomics Visium HD spatial transcriptomics platform. Whole-transcriptome data were collected at 2μm resolution, and adjacent squares were aggregated into 8μm regions to approximate single-cell dimensions. Cell identity was determined using the RCTD algorithm (v1.2.0) with integrated single-cell RNA-seq data from the WT and CKO mice. Machine learning techniques were employed to assign aggregated transcriptomic data to individual cells and calculate the spatial distances between fibroblasts and macrophages. Results: Seventeen cell types and ten spatial regions were identified in WT and CKO lungs (Figure A), consistent with histological findings. CKO mice displayed prominent regions of fibrosis and inflammation. Specifically, regions corresponding to inflammation (Region 2), perivascular fibrosis (Region 5), and perivascular smooth muscle (Region 7) were expanded in CKO lungs, while capillary endothelial regions (Regions 4, 6, and 8) were markedly reduced. Notably, the spatial distance between fibroblasts and macrophages was significantly reduced in CKO lungs (Figure B). Conclusion: High-resolution spatial transcriptomics (Visium HD) effectively delineates anatomical and molecular changes in PH lungs. The reduced spatial distance between fibroblasts and macrophages in PH mice suggests increased cellular interactions that may drive pulmonary vascular remodeling and contribute to PAH pathogenesis. Keywords: Pulmonary Arterial Hypertension, Spatial transcriptomics, High resolution, Macrophages, Fibroblasts

Background: Myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis (MF), are chronic leukemias associated with cardiovascular (CV) disease (CVD), including pulmonary hypertension (PH). Prior studies utilizing echocardiography for identifying PH in MPNs have suggested an association between PH and adverse outcomes. However, right heart catheterization (RHC) is required for diagnosis and hemodynamic profiling of PH. Data on RHC-proven PH in MPNs are sparse. Methods: We conducted a multicenter study of patients with MPN who underwent RHC. PH, defined as mean pulmonary artery pressure (mPAP) &gt; 20 mmHg, was hemodynamically characterized into isolated pre-capillary (pre-cap), isolated post-capillary (post-cap), and combined pre- and post-capillary (Cpc-PH). Outcomes were heart failure hospitalization (HFH) or CV death, and all-cause death. Multivariable Cox proportional hazards regression was performed. To model total number of HFH, multivariable negative binomial regression was performed. Results: 85 patients were included, 70 (82.4%) had PH, 37 (43.5%) were female, and 68 (80.0%) were White. Among PH patients, 30 (42.9%) had pre-cap PH, 12 (17.1%) post-cap PH, and 28 (40.0%) Cpc-PH. Age, gender, time from MPN to RHC, MPN type and driver and non-driver mutations did not differ between patients with or without PH. Patients with PH were more likely to have prior HFH (35.7% vs 0%, p = 0.006). After a median follow-up of 31.4 months, HFH or CV death occurred in 57 (67.1%) patients and death in 49 (57.6%). After adjustment, pre-cap (aHR 2.69, 95% CI 1.00 – 7.27) and post-cap PH were associated with increased risk of HFH or CV death (aHR 4.12, 95% CI 1.26 – 13.50) versus no PH. After multivariable negative binomial regression, any PH (IRR 3.36, 95% CI 1.31 – 8.63), pre-cap PH (IRR 4.11, 95% CI 1.60 – 10.58) and post-cap PH (IRR 5.06, 95% CI 1.63 – 15.67) were associated with increased total HFH. Conclusions: Among patients with MPN who underwent RHC, PH is common and appears to be predominantly isolated pre-capillary and Cpc-PH. Isolated pre- and isolated post-capillary PH were associated with increased HFH. Our study is confounded by selection bias, and therefore prospective studies of PH as diagnosed with RHC are needed in MPNs.