Increase In Right Ventricular Systolic Pressure Research Articles

Right ventricular diastolic adaptation to pressure overload in different rat strains.

Different rat strains are used in various animal models of pulmonary hypertension and right ventricular (RV) failure. No systematic assessment has been made to test differences in RV response to pressure overload between rat strains. We compared RV adaptation to pulmonary trunk banding (PTB) in Wistar (W), Sprague Dawley (SD), and Fischer344 (F) rats by hemodynamic profiling focusing on diastolic function. Age-matched male rat weanlings were randomized to sham surgery (W-sham, n = 5; SD-sham, n = 4; F-sham, n = 4) or PTB (W-PTB, n = 8; SD-PTB, n = 8; F-PTB, n = 8). RV function was evaluated after 5 weeks by echocardiography, cardiac MRI, and invasive pressure-volume measurements. PTB caused RV failure and increased RV systolic pressures four-fold in all three PTB groups compared with sham. W- and SD-PTB had a 2.4-fold increase in RV end-systolic volume index compared with sham, while F-PTB rats were less affected. Diastolic and right atrial impairment were evident by increased RV end-diastolic elastance, filling pressure, and E/e' in PTB rats compared with sham, again F-PTB the least affected. In conclusions, PTB caused RV failure with signs of diastolic dysfunction. Despite a similar increase in RV systolic pressure, F-PTB rats showed less RV dilatation and a more preserved diastolic function compared with W- and SD-PTB.

Right ventricular systolic pressure is an independent risk factor of all-cause death and inappropriate therapies in patients with implanted CRT-D

Abstract Introduction Cardiac resynchronization therapy-defibrillators (CRT-D) are implanted mostly in patients with low left ventricular ejection fraction (LVEF) and wide QRS. In such subjects, there is often a concomitant right ventricular (RV) dysfunction, which has been associated with higher long-term mortality. However, data on the association between RV dysfunction and arrhythmic outcomes in patients with CRT-D are scarce. Purpose To define whether there is any association between right ventricular dysfunction and antiarrhythmic therapies or all-cause mortality in patients with HF and CRT-D. Methods The clinical and demographic data of patients enrolled in this study were obtained from the single-centre COMMIT-HF registry. The parameters regarding right ventricular function, such as right ventricle dimension (RVD), tricuspid annular systolic plane systolic excursion (TAPSE) and right ventricular systolic pressure (RVSP) were obtained from electronic patients’ records. The data on the long-term hard endpoints were obtained from the national healthcare provider, while the data on the risk of arrhythmic events, CRT-D shocks and antitachycardia pacing (ATP) were obtained from investigator-initiated and -adjudicated single-centre remote monitoring database updated annually. Multivariable stepwise logistic regression was used to determine independent predictors of the study outcomes, being all-cause death, and the occurrence of appropriate and inappropriate CRT-D therapies. Results During the period between July, 2009 and November, 2019, 335 patients were enrolled at the RM programme after implantation of CRT-D. Of them, during the median (Q1-Q3) follow-up period of 5.3 (2.8-6.6) years, (113 (33.7%) died, 111 (33.1%) received appropriate and 37 (11%) inappropriate therapies. In the multivariable analysis, the independent predictors of all-cause death were reduction in LVEF and increase in RVSP. Lower age and increased LVEDD were independent predictors of appropriate therapies, while lower age and increased RVSP were independent predictors of inappropriate therapies. No association between TAPSE and RVD and outcomes was found. Conclusions Among right ventricular dysfunction parameters, RVSP is an independent predictor of inappropriate therapies and all-cause death, but not of appropriate therapies in patients with HF and CRT-D.

Usefulness of cardiopulmonary exercise test combined with exercise stress echocardiography in mild chronic thromboembolic pulmonary disease.

Chronic thromboembolic pulmonary disease (CTEPD) can lead to exercise limitations even without right ventricular (RV) dysfunction or pulmonary hypertension at rest. Combining exercise stress echocardiography with cardiopulmonary exercise testing (ESE-CPET) for RV function and pressure changes combined measuring overall function may be useful for CTEPD evaluation. This study aims to investigate CPET and ESE results to elucidate the mechanisms of exercise limitation in mild CTEPD cases. Among our CTEPD registry, 50 patients who performed both right heart catheterization data of mild disease (less than 30mm Hg of mean pulmonary arterial pressure (mPAP)) and ESE-CPET were enrolled.Echocardiography and CPET-derived parameters were compared with hemodynamic parameters measured through right heart catheterization. Peak VO2 (maximal oxygen consumption) was decreased in overall population (71.3±16.3% of predictive value). Peak VO2 during exercise was negatively correlate with mPAP and pulmonary vascular resistance at rest. A substantial increase in RV systolic pressure (RVSP) was observed during exercise (RVSP: pre-exercise 37.2±11.8mm Hg, postexercise 64.3±24.9mm Hg, p-value<.001). Furthermore, RV function deteriorated during exercise when compared to the baseline (RV fractional area change: 31.5±10.0% to 37.8±7.0%, p-value<.001; RV global longitudinal strain: -17.1±4.2% to -17.7±3.3%, p-value<.001) even though basal RV function was normal. While an excessive increase in RVSP during exercise was noticed in both groups, dilated RV and RV dysfunction during exercise were demonstrated only in the impaired exercise capacity group. CTEPD patients with mild PH or without PH exhibited limited exercise capacity alongside an excessive increase in RVSP during exercise. Importantly, RV dysfunction during exercise was significantly associated with exercise capacity. ESE-CPET could aid in comprehending the primary cause of exercise limitation in these patients.

Intratracheally Administered Peptide-Modified Lipid Admixture Containing Fasudil and/or DETA NONOate Ameliorates Various Pathologies of Pulmonary Arterial Hypertension.

This study examined the therapeutic potential of a combination therapy using fasudil, a Rho-kinase inhibitor, and DETA NONOate (DN), a nitric oxide donor, delivered as a lipid admixture modified with a cyclic homing peptide known as CAR (CAR-lipid mixture) for the treatment of pulmonary arterial hypertension (PAH). CAR-lipid mixtures were initially prepared via a thin-film hydration method and then combined with fasudil, DN, or a mixture of both. The therapeutic efficacy of this drug-laden lipid mixture was evaluated in a Sugen/Hypoxia (Su/Hx) rat model of PAH by measuring RV systolic pressure (RVSP), mean pulmonary arterial pressure (mPAP), Fulton indices, and assessing right ventricular (RV) functions, as well as evaluating pulmonary vascular morphology. Rats that received no treatment exhibited increases in RVSP, mPAP, Fulton indices, and changes in RV functional parameters. However, the treatment with the CAR-lipid mixture containing either fasudil or DN or a combination of both led to a decline in mPAP, RVSP, and Fulton indices compared to saline-treated rats. Similarly, rats that received these treatments showed concurrent improvement in various echocardiographic parameters such as pulmonary acceleration time (PAT), tricuspid annular plane systolic excursion (TAPSE), and ventricular free wall thickness (RVFWT). A significant decrease in the wall thickness of pulmonary arteries larger than 100 µm was observed with the combination therapy. The findings reveal that fasudil, DN, and their combination in a CAR-modified lipid mixture improved pulmonary hemodynamics, RV functions, and pathological alterations in the pulmonary vasculature. This study underscores the potential of combination therapy and targeted drug delivery in PAH treatment, laying the groundwork for future investigations into the optimization of these treatments, their long-term safety and efficacy, and the underlying mechanism of action of the proposed therapy.

Left atrial stiffness and sex differences in atrial fibrillation recurrence after catheter ablation

Abstract Background Atrial fibrillation (AF) occurs more frequently in men, but women suffer more AF recurrence; mechanisms are not completely understood. Purpose To explore whether sex related differences in LA stiffness (LAstiffn) in patients with AF ablation could potentially explain differences in AF recurrence. Methods We screened patients with catheter ablation for AF, in sinus rhythm at 3 months post-ablation, with no significant mitral valve disease (&amp;lt; moderate), and with prospectively measured LA volumes [maximum (LAVI) and minimum volume index] by echocardiography. LAStiffn index was estimated as (E/e’)/LA emptying fraction. Outcome endpoint was AF recurrence up to 14 years post ablation. Results A total of 591 patients with AF ablation were studied (mean age 60±10 years; 25% women; Table1). At 3 months post-ablation, LAVI was 36±10 mL/m2 and LAstiffn was 0.31±0.21 1/%. Compared to males, female patients were slightly older, had more frequently hypertension, congestive heart failure, prior stroke/TIA, higher CHA2DS2-VASc score; they less often had persistent AF, coronary artery disease, or dilated cardiomyopathy. Women also had higher LAstiffn (0.37±0.24 vs. 0.29±0.19, P &amp;lt;.0001, Figure 1), despite similar indexed LA volumes (Table1). Rates of AF recurrence at follow-up (median 7.5 years; 347 patients with events) were higher in women vs. men (Figure 2, left; log-rank P&amp;lt;.001) and persisted after adjustment for age, type and duration of AF, body mass index, cardiovascular risk factors and comorbidities, CHA2DS2-VASc score ≥2, LV ejection fraction, and LAVI (adjusted HR 1.58 [1.20-2.08], P=.001). Overall, LA volumes and LAstiffn were higher in patients with older age and more comorbidities (hypertension, congestive heart failure, coronary artery disease, persistent AF, CHA2DS2-VASc score ≥2, etc; P&amp;lt;.01 for all). At multivariable regression analysis, LAVI and LAstiffn correlated with E/e’, LV size and mass, degree of mitral/tricuspid regurgitation, and LV stroke volume index (only LAVI). In addition, LAstiffn was higher in patients with elevated right ventricular systolic pressure (RVSP) &amp;gt;35 mmHg and increase in RVSP more than 10 mmHg from pre-ablation (P&amp;lt;.0001) (correlation R=0.44, P&amp;lt;.0001). At follow-up, after adjusting for age and LAVI, higher LAstiffn remained associated with AF recurrence in women (P=.02, HR 2.82 per unit change, 95% CI, 1.08-6.72; Figure 2, right), but not in men (P=.30). Conclusions LAStiffn is higher in women vs. men and correlates with burden of comorbidities, aging, diastolic dysfunction and pulmonary hypertension, possibly reflecting more extensive LA myopathy, and potentially contributing to sex differences in AF recurrence.Figure 1Table 1

Right ventricular diastolic adaptation to pressure overload in different rat strains

Abstract Background Different rat strains are used in various animal models of pulmonary hypertension and right ventricular (RV) failure. No systematic assessment has been performed to test differences in RV response to pressure overload between rat strains. Purpose We compared RV adaptation to pulmonary trunk banding (PTB) in Wistar, Sprague Dawley, and Fischer344 rats by hemodynamic profiling focusing on diastolic function. Methods Age-matched male rat weanlings were randomized to sham operation (Wistar sham, n=5; Sprague Dawley sham, n=4; Fischer344 sham, n=4) or PTB (Wistar PTB, n=8; Sprague Dawley PTB, n=8; Fischer344 PTB, n=8). RV function was evaluated after five weeks by echocardiography, cardiac MRI, and invasive pressure-volume measurements and RV remodelling assessed by histological analyses. Results At end of study, Fischer344 rats weighed 25 % less than Wistar and Sprague Dawley rats. PTB increased RV systolic pressures four-fold, and RV failure was evident by a decrease in cardiac index (Wistar PTB: 1.8±0.2 mL/s/m2 vs. Wistar sham: 3.9±0.2 mL/s/m2, p&amp;lt;0.0001; Sprague Dawley PTB: 1.7±0.1 mL/s/m2 vs. Sprague Dawley sham: 3.0±0.3 mL/s/m2, p=0.0029; Fischer344 PTB: 2.1±0.2 mL/s/m2 vs. Fischer344 sham: 3.8±0.3 mL/s/m2, p&amp;lt;0.0001). There was a 2.4-fold increase in RV end-systolic volume index in Wistar PTB and Sprague Dawley PTB compared with sham, while Fischer344 PTB rats were less affected with only a 2.0-fold increase in RV end-systolic volume index compared with Fischer344 sham. Diastolic and right atrial impairment were evident by increased end-diastolic elastance, filling pressure, and E/e’ in PTB rats compared with sham, again Fischer344 PTB the least affected. PTB increased RV fibrosis in all groups compared with sham, though Fischer344 PTB showed a trend towards a smaller increase in RV fibrosis (Fischer344 PTB: 9.2±0.4 % vs Wistar PTB: 10.7±0.2 %, p=0.0919). Conclusions PTB caused RV failure in all rats subjected to the procedure including signs of diastolic dysfunction. Despite similar increase in RV systolic pressure, Fischer344 PTB rats showed less RV dilatation and where more able to sustain diastolic function compared with Wistar and Sprague Dawley PTB rats. All three rat strains are suitable for PTB and studies of RV failure.

Exosomes derived from mesenchymal stromal cells exert a therapeutic effect on hypoxia-induced pulmonary hypertension by modulating the YAP1/SPP1 signaling pathway

ObjectiveHypoxic pulmonary hypertension (HPH) is a progressive and life-threatening disease characterized by perivascular inflammation, pulmonary vascular remodeling, and occlusion. Mesenchymal stromal cell-derived exosomes (MSC-exo) have emerged as potential therapeutic agents due to their role in cell communication and the transportation of bioactive molecules. In this study, we aimed to investigate the therapeutic effects of MSC-exo against HPH and elucidate the underlying molecular mechanism. MethodsExosomes were isolated from conditioned media of human bone mesenchymal stromal cells using ultracentrifugation and characterized through western blotting, transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). An HPH animal model was established in male SD rats, and MSC-exo or phosphate-buffered saline (PBS) were administered via the tail vein for three weeks. Subsequently, right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), and pulmonary vascular remodeling were evaluated. Lung tissues from HPH rats and normal rats underwent high-throughput sequencing and transcriptomic analysis. Gene Ontology (GO) analysis was employed to identify upregulated differentially expressed genes. Additionally, rat pulmonary artery smooth muscle cells (PASMC) exposed to platelet-derived growth factor-BB (PDGF-BB) were used to simulate HPH-related pathological behavior. In vitro cellular models were established to examine the molecular mechanism of MSC-exo in HPH. ResultsMSC-exo administration protected rats from hypoxia-induced increases in RVSP, RVHI, and pulmonary vascular remodeling. Additionally, MSC-exo alleviated PDGF-BB-induced proliferation and migration of PASMC. Transcriptomic analysis revealed 267 upregulated genes in lung tissues of HPH rats compared to control rats. Gene Ontology analysis indicated significant differences in pathways associated with Yes Associated Protein 1 (YAP1), a key regulator of cell proliferation and organ size. RT-qPCR and western blot analysis confirmed significantly increased expression of YAP1 in HPH lung tissues and PASMC, which was inhibited by MSC-exo treatment. Furthermore, analysis of datasets demonstrated that Secreted Phosphoprotein 1 (SPP1), also known as Osteopontin (OPN), is a downstream binding protein of YAP1 and can be upregulated by PDGF-BB. MSC-exo treatment reduced the expression of both YAP1 and SPP1. Lentivirus-mediated knockdown of YAP1 inhibited PDGF-BB-induced PASMC proliferation, migration, and SPP1 protein levels. ConclusionOur findings demonstrate that MSC-exo exert a therapeutic effect against hypoxia-induced pulmonary hypertension by modulating the YAP1/SPP1 signaling pathway. The inhibition of YAP1 and downstream SPP1 expression by MSC-exo may contribute to the attenuation of pulmonary vascular remodeling and PASMC proliferation and migration. These results suggest that MSC-exo could serve as a potential therapeutic strategy for the treatment of HPH. Further investigations are warranted to explore the clinical applicability of MSC-exo-based therapies in HPH patients.

TNF-α and IL-8 levels are positively correlated with hypobaric hypoxic pulmonary hypertension and pulmonary vascular remodeling in rats.

The expression status of proinflammatory cytokines in high-altitude pulmonary arterial hypertension (PAH) has been well studied. However, the changes in interleukin (IL)-8 and tumor necrosis factor α (TNF-α) during the reversible changes in pulmonary vascular remodeling (PVR) in PAH after detaching from a hypobaric hypoxic environment have not been elucidated. This investigation elucidated a high-altitude PAH rat model. Then, PAH rats in the high-altitude group were maintained in the high-altitude area, and rats in the low-altitude group returned to the low-altitude area. After 0, 10, 20, and 30 days of PAH modeling, right ventricular systolic pressure (RVSP) and the mean pulmonary arterial pressure (mPAP) were assessed. Right ventricular (RV) hypertrophy was reflected by the ratio of RV/[left ventricle + interventricular septum (S)]. Pathological changes in PVR were accessed by hematoxylin-eosin staining, and medial wall thickness (WT%) and medial wall area (WA%) were measured. TNF-α and IL-8 levels in pulmonary artery tissues and blood were measured with Western blot assay and enzyme-linked immunosorbent assay, respectively. Our results showed that PAH rats exhibited a substantial increase in RVSP and mPAP, RV hypertrophy, PVR, and enhanced generation of TNF-α and IL-8. Then, we found that these pathological changes were gradually aggravated and TNF-α and IL-8 levels were increased in rats in the high-altitude group after 10, 20, and 30 days of PAH modeling. In contrast, the mPAP was decreased and PVR was alleviated in rats in the low-altitude group, accompanying with reduced TNF-α and IL-8 production. In conclusion, our study demonstrated that the generation of TNF-α and IL-8 was also reversible during the reversible changes in PVR after detaching from a hypobaric hypoxic environment. Thus, proinflammatory cytokine TNF-α and IL-8 levels are positively correlated with PVR severity.

Cardiometabolic Risk Factors Associated With Right Ventricular Function and Compensation in Patients Referred for Echocardiography.

Background Pulmonary hypertension and right ventricular (RV) dysfunction are drivers of adverse outcomes; however, modifiable risk factors for RV dysfunction are not well described. We investigated the association between clinical markers of metabolic syndrome and echocardiographic RV function in a large referral population. Methods and Results Using electronic health record data, we performed a retrospective cohort study of patients aged ≥18 years referred for transthoracic echocardiography between 2010 and 2020 with RV systolic pressure (RVSP) or tricuspid annular plane systolic excursion (TAPSE) values. Pulmonary hypertension was defined by RVSP >33 mm Hg and RV dysfunction by TAPSE ≤1.8 cm. Our sample included 37 203 patients of whom 19 495 (52%) were women, 29 752 (83%) were White, with a median age of 63 years (interquartile range, 51-73). Median (interquartile range) RVSP was 30.0 mm Hg (24.0-38.7), and median TAPSE was 2.1 cm (1.7-2.4). Within our sample, 40% had recorded RVSP >33 mm Hg, and 32% with TAPSE <1.8 cm. Increase in RVSP from normal (<33 mm Hg) to mildly elevated (33-39 mm Hg) or elevated (>39 mm Hg) was associated with lower low-density lipoprotein and high-density lipoprotein, and higher hemoglobin A1c and body mass index (P<0.001). A decrease in TAPSE between groups of TAPSE >1.8 cm, TAPSE 1.5-1.8 cm, and TAPSE <1.5 cm was associated with increased triglyceride:high-density lipoprotein ratio and hemoglobin A1c, and decreased body mass index, low-density lipoprotein, high-density lipoprotein, and systolic blood pressure (P<0.001). Most associations between cardiometabolic predictors and RVSP and TAPSE were nonlinear with clear inflection points associated with higher pulmonary pressure and lower RV function. Conclusions Clinical measures of cardiometabolic function were highly associated with echocardiographic measures of right ventricular function and pressure.

Sympathetic Spleen Denervation Attenuate Pulmonary Hypertension by Decreasing Lung Infiltration of Hematopoietic Stem Cells And Neuroinflammation

Background: Pulmonary Hypertension (PH) is a severe disease characterized by increased pulmonary arterial pressure that ultimately leads to right heart failure. Previous studies have indicated PH as a disease that affects several other organ systems in addition to the lungs. Of particular interest has been the brain and its contribution to the pathogenesis of PH. Neural control of immunity and inflammation is well-established in the literature, whereby sympathetic-mediated emergency granulopoiesis from the spleen is a critical source for the inflammatory process in different diseases. Aim: Investigate the hypothesis of a feedforward loop involving increased sympathetic activity and hematopoietic stem cells (HSCs). In this hypothesis, infiltration of HSC to the brain contributes to neuroinflammation, maladaptive neuroplasticity in preautonomic neurons, and consequently, autonomic disbalance, which contributes to increased inflammatory response and severity of PH. Method: Sympathetic denervation of spleen was performed in C57BL6-J mice (n=40) using absolute ethanol/saline repeatedly applied in the splenic hilum. Following completion of either splenic denervation or sham surgery, animals were allowed to recover for 6 weeks before exposure to either Chronic Hypoxia (CH-PH; FIO2 10%) or normoxia (room air, FIO2 21%) for 4 weeks. Then, right ventricular systolic pressure (RVSP) was recorded, followed by harvest of tissues. Alpha-smooth muscle actin (αSMC) and Masson trichrome staining in the lungs was used for characterization of pulmonary hypertension. Immune cell profile in the lung, spleen and brain was performed by flow cytometry. Iba1 staining was used to label microglia/macrophage cells. Together, histological and flow data were used to evaluate whether the neuroinflammation observed in CH-PH is dependent/independent of sympathetic-mediated infiltration of myeloid precursors from the circulation to preautonomic nuclei such as the paraventricular nucleus of the hypothalamus (PVN). TH staining was performed in the spleen of all animals to confirm the spleen denervation. Result: Sympathetic spleen denervation attenuated the increase of RVSP, Iba1+ cells within the PVN and proliferation of αSMC and collagen in the lungs induced by CH. Furthermore, sympathetic denervation also blunted the changes in the catecholamine metabolism in PMN-MDSC cells within the lung and altered TREM2+ microglia cells’ response to CH. Conclusion: Our previous experiments demonstrated that the exposure of chimeric mice with GFP bone marrow cells to chronic hypoxia illustrates the translocation of these cells into the brain of PH animals. Current experiments show that sympathetic spleen denervation attenuates the infiltration of hematopoietic cells to the PVN and PH development. Together, these results indicate that hematopoietic cells may contribute directly to lung inflammation as well as to the dysfunctional neuro-immune axis observed in PH. NIH grant HL102033, HL110170, HL142776; AHA 20POST35210516 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comparison of Tricuspid Regurgitation Severity Between Cardiac Resynchronization Therapy Versus Right Ventricular Pacing in Patients With Chronic Obstructive Pulmonary Disease

BackgroundRight ventricular (RV) lead placement can worsen tricuspid regurgitation (TR). TR is known to be associated with lower survival irrespective of left ventricular ejection fraction (LVEF) or pulmonary hypertension (PH). Patients with chronic obstructive pulmonary disease (COPD) often have PH and pre-existent TR with higher morbidity and mortality from worsening TR. Prior studies are lacking to indicate if cardiac resynchronization therapy (CRT) may be more beneficial in lessening TR in COPD patients. Therefore, we sought to study if patients with COPD will have less TR with CRT versus non-CRT devices.MethodsWe performed a retrospective, single-center analysis on 154 COPD patients (mean age = 71.69 ± 10.58, males = 54.14%) that required single-chamber (n = 27), dual-chamber (n = 90), or CRT (n = 37) devices. TR severity, LVEF and right ventricular systolic pressure (RVSP) were evaluated by two cardiologists in a blinded fashion. Analysis of variance (ANOVA) and Chi-square tests were applied for continuous and categorical variables respectively. The primary endpoint was a change in the severity of TR comparing pre-device versus post-device echocardiogram. Secondary endpoints included changes in LVEF and RVSP.ResultsCOPD patients, who underwent a CRT device had a significantly lower incidence of worsening TR (16%) when compared to single- (37%) (P = 0.001) and dual-chamber devices (30%) (P = 0.02). The increase in RVSP was similar between the groups. There was an expected improvement in LVEF in the CRT group.ConclusionsCOPD patients receiving a CRT device were least likely to have worsening TR, compared to single- or dual-chamber devices. Since both COPD and progression in TR may result in poor outcomes, our study may suggest that an upfront strategy of CRT rather than a single- or dual-chamber device may be more beneficial in COPD patients, especially with pre-existent TR.

Alterations in Genes Associated with Bioactive Lipid Pathways during Development of Pulmonary Hypertension in Rat SU5416‐Hypoxia Model of Severe Pulmonary Arterial Hypertension

BackgroundPulmonary arterial hypertension (PAH) is a disease of the pulmonary vascular system characterized by sustained elevation in resting mean pulmonary arterial pressure (&gt;25 mmHg) with presence of occlusive vascular remodeling and progressive loss of microvasculature. PAH patients have a poor five‐year survival rate of only ~50% and the primary cause of death for PAH patients is the right (‐sided) heart failure. Better understanding of pathophysiology of PAH and RHF is required to find novel therapies. In this project, using a rat model of severe PAH, we explored the alterations in expression of genes involved in bioactive lipid pathways in the lungs and the right ventricle (RV) during development of PAH.MethodsAdult male Sprague Dawley rats were administered a single injection of SU5416 (SU; 20 mg/kg, subcutaneous) and subjected to 3 weeks of hypoxia (10% O2) followed by 4 weeks of normoxia (room air), SUHx model of sever PAH. Right ventricular systolic pressure (RVSP) was measured, and heart and lung samples were collected at 1, 3, 7, 21 and 49‐days post SU injection. Histological analysis was conducted to confirm vascular remodeling in the lungs and development of RV hypertrophy (RVH; RV/LV+S). RTqPCR was performed to evaluate gene expression changes in the genes related to bioactive lipids pathways.ResultsIn response to SUHx, progressive increase in RVSP and RVH was observed. Histology of lungs and heart samples confirmed pulmonary vascular and RV remodeling at 7 weeks post SU in the SUHx model. We observed increase in expression of ALOX‐5 in the RV and lungs of SUHx rats, compared to controls. Furthermore, alterations in various cytochrome P450 (CYP) isozymes were observed in the RV and lungs of SUHx rats compared to controls.ConclusionsTogether, we have identified unique changes in bioactive lipid pathway genes in the lungs and the RV that were associated with development of PAH and RV remodeling in SUHx model. Further studies are ongoing to confirm the role of the candidate genes in pathophysiology of PAH and development of RHF.

Upregulation of endothelial hypoxia‐inducible factor‐2 alpha in animals with pulmonary hypertension

IntroductionIdiopathic pulmonary arterial hypertension (IPAH) is a life‐threatening disease with no cure. Pulmonary vascular remodeling due to increased pulmonary artery smooth muscle (PASMC) and lung vascular endothelial cell (LVEC) proliferation is a major cause for the elevated pulmonary vascular resistance (PVR) and pulmonary arterial pressure (PAP) in patients with IPAH. We have previously demonstrated that endothelial hypoxia‐inducible factor‐2α (HIF‐2α) contributes to the development of pulmonary vascular remodeling in LVEC isolated from IPAH patients. Moreover, HIF‐2α is involved in the initiation of endothelial‐to‐mesenchymal transition (EndMT) by upregulating Snai1 and Snai2 (EndMT drivers). However, the exact role of HIF‐2α in the development and progression of pulmonary hypertension (PH) remains elusive. We aimed to investigate whether endothelial HIF‐2α is involved in pulmonary vascular remodeling in animals with hypoxia/sugen‐induced PH (SuHx‐PH) and monocrotaline‐induced PH (MCT‐PH).MethodsHypoxia/sugen‐PH (SuHx‐PH) model in mice was induced by exposing animals to the combination of normobaric hypoxia (10% O2) and sugen 5416 (20 mg/kg, i.p., weekly) for 6 weeks. Monocrotaline‐MCT‐PH model in rats was induced by single administration of MCT (60 mg/kg, s.c.) followed by experimental measurements after 28 days. Body weight (BW) was collected from all animals weekly. Hemodynamic parameters including right ventricular systolic pressure (RVSP), mean pulmonary arterial pressure (mPAP), the Fulton index (FI), right ventricular (RV) contractility, heart rate (HR) were measured to establish PH. The pulmonary artery (PA) wall thickness was estimated by H&amp;E staining. The protein expression of Snai1 and HIF‐2α was determined by Western blot and immunocytochemistry. Normal human LVEC was treated with TGF‐β1 for 7 days to induce EndMT. LVEC isolated with patients with IPAH was treated with HIF‐2α inhibitor Compound 2 for 8‐48 hrs.ResultsExposure of mice to the SuHx (6 weeks) or rats to MCT (4 weeks) resulted in the significant increase of RVSP, mPAP, RV contractility, and FI compared to control animals. We did not detect any changes in HR between corresponded groups. BW was decreased by 7% after the first week of the SuHx treatment in mice. By the end of 6 weeks BW was significantly lower by 12% in SuHx mice compared with normoxic animals. BW in MCT‐treated rats was 5% lower after the first week and at the end of experiment compared to vehicle‐treated animals. Pulmonary vascular remodeling estimated by PA wall thickness was enhanced in both SuHx‐PH mice and MCT‐PH rats. The protein expression of HIF‐2α and Snai1 was higher in lung tissues isolated from SuHx‐PH mice and MCT‐PH rats compared to controls. Moreover, HIF‐2α and Snai1 was activated in normal human LVEC treated with TGF‐β1 (10ng/ml) for 7 days. Additionally, HIF‐2α inhibitor, Compound 2 (30µM) was able to downregulate Snai1 protein expression in LVEC isolated from IPAH patients after 16 hours.ConclusionsOur results indicate that HIF‐2α is involved in pulmonary vascular remodeling in animals with PH. Our studies support the premise that targeting HIF‐2α would be a novel therapeutic approach for the treatment of IPAH and other forms of PH.

Notch4 mediates vascular remodeling via ERK/JNK/P38 MAPK signaling pathways in hypoxic pulmonary hypertension

BackgroundHypoxic pulmonary hypertension (HPH) is a chronic progressive advanced disorder pathologically characterized by pulmonary vascular remodeling. Notch4 as a cell surface receptor is critical for vascular development. However, little is known about the role and mechanism of Notch4 in the development of hypoxic vascular remodeling.MethodsLung tissue samples were collected to detect the expression of Notch4 from patients with HPH and matched controls. Human pulmonary artery smooth muscle cells (HPASMCs) were cultured in hypoxic and normoxic conditions. Real-time quantitative PCR and western blotting were used to examine the mRNA and protein levels of Notch4. HPASMCs were transfected with small interference RNA (siRNA) against Notch4 or Notch4 overexpression plasmid, respectively. Cell viability, cell proliferation, apoptosis, and migration were assessed using Cell Counting Kit-8, Edu, Annexin-V/PI, and Transwell assay. The interaction between Notch4 and ERK, JNK, P38 MAPK were analyzed by co-immunoprecipitation. Adeno-associated virus 1-mediated siRNA against Notch4 (AAV1-si-Notch4) was injected into the airways of hypoxic rats. Right ventricular systolic pressure (RVSP), right ventricular hypertrophy and pulmonary vascular remodeling were evaluated.ResultsIn this study, we demonstrate that Notch4 is highly expressed in the media of pulmonary vascular and is upregulated in lung tissues from patients with HPH and HPH rats compared with control groups. In vitro, hypoxia induces the high expression of Delta-4 and Notch4 in HPASMCs. The increased expression of Notch4 promotes HPASMCs proliferation and migration and inhibits cells apoptosis via ERK, JNK, P38 signaling pathways. Furthermore, co-immunoprecipitation result elucidates the interaction between Notch4 and ERK/JNK/P38. In vivo, silencing Notch4 partly abolished the increase in RVSP and pulmonary vascular remodeling caused by hypoxia in HPH rats.ConclusionsThese findings reveal an important role of the Notch4-ERK/JNK/P38 MAPK axis in hypoxic pulmonary remodeling and provide a potential therapeutic target for patients with HPH.

Echocardiographic Findings in Patients (pts) Receiving Tyrosine Kinase Inhibitors (TKIs) for the Treatment of Chronic Myeloid Leukemia (CML)

INTRODUCTIONTKIs are standard therapy for pts with CML, with therapy continued over several years and in many instances indefinitely. Cardiac effects of TKIs have been described, including prolongation of QTc and arterio-thrombotic events. Echocardiographic manifestations have been reported including a reduction in left ventricular ejection fraction (EF) and an increase in right atrial pressure (RAP) and right ventricular systolic pressure (RVSP). However, no systematic description of these changes over the course of therapy has been presented. We retrospectively examined features and course of treatment of CML pts who had undergone echocardiogram during or following treatment with TKI therapy.METHODSWe interrogated medical records for pts with CML who had undergone echocardiogram (ECHO). Pts were grouped by TKI and analyzed their age, race, sex, line of therapy, duration of therapy, and change of TKIs. Variables were analyzed using general linear model (for continuous variables), or chi-square test or Fisher's exact test (for categorical variables). T-test was used to compare EF, RVSP, and RAP measure before vs. during and during vs. after index TKI for patients with sequential ECHOs. To compare echocardiograph findings by TKI we used separate repeated measures ANOVAs for EF, RVSP, and RAP for patients with sequential ECHOs. All statistical analyses were conducted using SAS v9.4.RESULTSA total of 146 ECHOs were performed on 111 pts. 11 pts had ECHO before, during, and after TKI treatment, 17 pts had ECHO before and during TKI treatment, and 20 had ECHO during and after TKI. Their median age was 53 yrs (range, 15-83), and 53.1% were male. 95 (86%) were in CP at the time of TKI start; 71 (64%) were receiving their 1st TKI. TKIs used included imatinib in 53 (400 mg n=19, 800 mg n=34), dasatinib in 39, and nilotinib in 19. Among patients with 3 sequential ECHOs, 9 were on dasatinib, 1 on imatinib (400 mg), and 1 on nilotinib. Among patients with ECHOs before and during treatment, 13 were on dasatinib, 2 on imatinib (800 mg), and 2 on nilotinib, while among patients with ECHOs during and after treatment, 16 were on dasatinib, 1 on nilotinib, 1 on imatinib (800 mg), and 1 on imatinib (400 mg). Pt characteristics are presented in Table 1.Considering all ECHOs in all pts, median EF was 62.5% before TKI, 60% during, and 60% after index TKI. Median RVSP was 30 mmHg before index TKI, 33 mmHg during, and 28 mmHg after TKI. Median RAP was stable at 5 mmHg throughout index TKI use. For patients with two sequential ECHOs, EF decreased significantly during TKI therapy (compared to baseline, difference=-3.1%, N=16, p=0.0186), and marginally after TKI (vs during, difference=-2.8%, N=20, p=0.091). There was a mild, non-statistically significant increase in RVSP from baseline to during TKI (difference=3.6 mmHg, N=16, p=0.30) and from during TKI to after TKI use (difference=1.9 mmHg, N=18, p=0.51). RAP did not differ from baseline to during TKI use (difference=1.1 mmHg, N=13, p=0.19), or during TKI to after TKI (difference=-0.71 mmHg, N=14, p=0.16). The results of these pairwise comparisons are presented in Figure 1. In repeated measures ANOVA of those patients with three sequential ECHOs, EF did not differ significantly among TKIs used (F=0.22, N=10, p=0.68), nor did RVSP (F=0.04, N=11, p=0.86). RAP was marginally different among TKIs used (F=9.53, N=11, p=0.054) (Figure 2). Full model results for these repeated measures ANOVAs are presented in Table 2.CONCLUSIONChronic administration of TKIs results in modest ECHO changes, particularly a slight decline in EF. There was also a modest increase in RAP with dasatinib and, to some extent, nilotinib but small sample size make these results preliminary. Still, monitoring of patients on TKIs with ECHOs at baseline and during therapy might be advisable. [Display omitted] DisclosuresKantarjian:ARIAD: Research Funding; Delta-Fly Pharma: Research Funding; Amgen: Research Funding; Pfizer: Research Funding; Bristol-Meyers Squibb: Research Funding; Novartis: Research Funding. Wierda:The University of Texas MD Anderson Cancer Center: Employment; GSK/Novartis: Consultancy, Honoraria, Research Funding; Genzyme: Consultancy, Honoraria; Acerta: Research Funding; Celgene: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Research Funding; Genentech/Roche: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding; Janssen: Research Funding; Juno: Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Merck: Consultancy, Honoraria; Emergent: Consultancy, Honoraria, Research Funding; Karyopharm: Research Funding; Kite: Research Funding; Sanofi: Consultancy, Honoraria. Jabbour:Bristol-Myers Squibb: Consultancy. Cortes:Pfizer: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding; ARIAD: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Sun Pharma: Research Funding; Teva: Research Funding.

Role of Hypoxia-Inducible Factors in Regulating Right Ventricular Function and Remodeling during Chronic Hypoxia–induced Pulmonary Hypertension

Pulmonary hypertension (PH) and right ventricular (RV) hypertrophy frequently develop in patients with hypoxic lung disease. Chronic alveolar hypoxia (CH) promotes sustained pulmonary vasoconstriction and pulmonary artery (PA) remodeling by acting on lung cells, resulting in the development of PH. RV hypertrophy develops in response to PH, but coronary arterial hypoxemia in CH may influence that response by activating HIF-1α (hypoxia-inducible factor 1α) and/or HIF-2α in cardiomyocytes. Indeed, other studies show that the attenuation of PH in CH fails to prevent RV remodeling, suggesting that PH-independent factors regulate RV hypertrophy. Therefore, we examined the role of HIFs in RV remodeling in CH-induced PH. We deleted HIF-1α and/or HIF-2α in hearts of adult mice that were then housed under normoxia or CH (10% O2) for 4 weeks. RNA-sequencing analysis of the RV revealed that HIF-1α and HIF-2α regulate the transcription of largely distinct gene sets during CH. RV systolic pressure increased, and RV hypertrophy developed in CH. The deletion of HIF-1α in smooth muscle attenuated the CH-induced increases in RV systolic pressure but did not decrease hypertrophy. The deletion of HIF-1α in cardiomyocytes amplified RV remodeling; this was abrogated by the simultaneous loss of HIF-2α. CH decreased stroke volume and cardiac output in wild-type but not in HIF-1α-deficient hearts, suggesting that CH may cause cardiac dysfunction via HIF-dependent signaling. Collectively, these data reveal that HIF-1 and HIF-2 act together in RV cardiomyocytes to orchestrate RV remodeling in CH, with HIF-1 playing a protective role rather than driving hypertrophy.

IRAG1 Deficient Mice Develop PKG1β Dependent Pulmonary Hypertension.

PKGs are serine/threonine kinases. PKG1 has two isoforms—PKG1α and β. Inositol trisphosphate receptor (IP3R)-associated cGMP-kinase substrate 1 (IRAG1) is a substrate for PKG1β. IRAG1 is also known to further interact with IP3RI, which mediates intracellular Ca2+ release. However, the role of IRAG1 in PH is not known. Herein, WT and IRAG1 KO mice were kept under normoxic or hypoxic (10% O2) conditions for five weeks. Animals were evaluated for echocardiographic variables and went through right heart catheterization. Animals were further sacrificed to prepare lungs and right ventricular (RV) for immunostaining, western blotting, and pulmonary artery smooth muscle cell (PASMC) isolation. IRAG1 is expressed in PASMCs and downregulated under hypoxic conditions. Genetic deletion of IRAG1 leads to RV hypertrophy, increase in RV systolic pressure, and RV dysfunction in mice. Absence of IRAG1 in lung and RV have direct impacts on PKG1β expression. Attenuated PKG1β expression in IRAG1 KO mice further dysregulates other downstream candidates of PKG1β in RV. IRAG1 KO mice develop PH spontaneously. Our results indicate that PKG1β signaling via IRAG1 is essential for the homeostasis of PASMCs and RV. Disturbing this signaling complex by deleting IRAG1 can lead to RV dysfunction and development of PH in mice.

Stim-activated TRPC-ORAI channels in pulmonary hypertension induced by chronic intermittent hypoxia.

Obstructive sleep apnea (OSA), a breathing disorder featured by chronic intermittent hypoxia (CIH) is associated with pulmonary hypertension (PH). Rodents exposed to CIH develop pulmonary vascular remodeling and PH, but the pathogenic mechanisms are not well known. Overexpression of Stim-activated Transient Receptor Potential Channels (TRPC) and Calcium Release-Activated Calcium Channel Protein (ORAI) TRPC-ORAI Ca2+ channels (STOC) has been involved in pulmonary vascular remodeling and PH in sustained hypoxia. However, it is not known if CIH may change STOC levels. Accordingly, we studied the effects of CIH on the expression of STOC subunits in the lung and if these changes paralleled the progression of the vascular pulmonary remodeling and PH in a preclinical model of OSA. Male Sprague-Dawley rats (∼200 g) were exposed to CIH (5%O2, 12 times/h for 8 h) for 14, 21, and 28 days. We measured right ventricular systolic pressure (RVSP), cardiac morphometry with MRI, pulmonary vascular remodeling, and wire-myographic arterial responses to KCl and endothelin-1 (ET-1). Pulmonary RNA and protein STOC levels of TRPC1, TRPC4, TRPC6, ORAI 1, ORAI 2, and STIM1 subunits were measured by qPCR and western blot, and results were compared with age-matched controls. CIH elicited a progressive increase of RVSP and vascular contractile responses to KCl and ET-1, leading to vascular remodeling and augmented right ventricular ejection fraction, which was significant at 28 days of CIH. The levels of TRPC1, TRPC4, TRPC 6, ORAI 1, and STIM 1 channels increased following CIH, and some of them paralleled morphologic and functional changes. Our findings show that CIH increased pulmonary STOC expression, paralleling vascular remodeling and PH.

Drag-reducing polymers attenuates pulmonary vascular remodeling and right ventricular dysfunction in a rat model of chronic hypoxia-induced pulmonary hypertension.

Drag-reducing polymers (DRPs) was previously demonstrated to increase blood flow, tissue perfusion, and reduce vascular resistance. The purpose of this study was to investigate the effect of DRPs on pulmonary vascular remodeling and right ventricular dysfunction in a rat model of chronic hypoxia-induced pulmonary hypertension (HPH). A total of forty male Wistar rats were randomly and equally assigned into four experimental groups (Group I: normoxia + saline, Group II: normoxia + PEO, Group III: hypoxia + saline, Group IV: hypoxia + PEO) and maintained in normoxia (21% O2) or hypobaric hypoxia (10% O2). After four weeks, comparisons were made of the following aspects: the mean pulmonary arterial pressure (mPAP), right ventricular systolic pressure (RVSP), right ventricular hypertrophy, wall thickness of pulmonary trunk and arteries, internal diameter of pulmonary arteries, cardiomyocyte cross-sectional area (CM CSA), and ultrastructure of right ventricular. Treatment with PEO in Group IV attenuated the increases in RVSP and mPAP (40.5±7.2 and 34.7±7.0 mmHg, respectively, both P < 0.05), compared with Group III. Distal vascular remodeling was visible as a significant increase in medial wall thickness (64.2±12.3% vs. 43.95±7.0%, P < 0.01) and a remarkable decrease in internal diameter of small pulmonary arteries (35.2±9.7μ m vs. 50.4±14.7μ m, P < 0.01) in Group III, to a greater extent than that detected in Group IV. Nevertheless, no significant histopathological differences in medial wall thickness was observed in pulmonary trunk between Group III and Group IV (P > 0.05), denoting that PEO chiefly attenuated the remodeling of small pulmonary arteries rather than main arteries in hypoxic environment. Infusion of DRPs (intravenous injection twice weekly) also attenuated the index of right ventricular hypertrophy, protected against the increase of cardiomyocyte cross-sectional area, and provided protection for cardiac ultrastructure. DRP treatment with intravenous injection elicited a protective effect against pulmonary vascular remodeling and right ventricular dysfunction in the rat model of HPH. DRPs may offer a new potential approach for the treatment of HPH, which may have theoretical significance and application value to society.

Impaired Endothelial Caveolin‐1‐TRPV4 Channel Signaling Contributes to Endothelial Dysfunction in Pulmonary Hypertension

Impaired endothelium‐dependent vasodilation is a key contributor to elevated pulmonary arterial pressure (PAP) in pulmonary hypertension (PH). While the mechanisms of pathogenesis of PH remain elusive, recent studies show that spatially localized Ca2+ influx via endothelial transient receptor potential vanilloid 4 (TRPV4EC) channels promotes vasodilation in resistance‐sized pulmonary arteries (PAs) by activating endothelial nitric oxide synthase (eNOS) and releasing nitric oxide (NO). Caveolin‐1 (Cav‐1EC) is an essential structural protein within the pulmonary endothelium, where it has been found to associate with TRPV4EC channels in cultured endothelial cells. We hypothesized that Cav‐1EC regulates TRPV4EC channel activity and PAP, and that impaired Cav‐1EC‐TRPV4EC signaling contributes to elevated PAP in PH. To test these hypotheses, we used right ventricular systolic pressure (RVSP) and PAP measurements in normoxic or chronic hypoxic Cav‐1EC−/− and TRPV4EC−/− mice, and pressure myography and high‐speed Ca2+ imaging studies in PAs from these mice. TRPV4EC channel activity and TRPV4EC‐mediated vasodilation were significantly impaired in PAs from Cav‐1EC−/− mice, suggesting that Cav‐1EC enhances TRPV4EC channel activity in PAs. Purinergic signaling plays an important role in pulmonary circulation, and we recently identified adenosine triphosphate (ATP) as a novel physiological activator of TRPV4EC channels in PAs. ATP activation of TRPV4EC channels was abolished by protein kinase C (PKC) inhibition, and was absent in the arteries from Cav‐1EC−/− mice, supporting a Cav‐1EC‐PKC‐TRPV4EC signaling that enables ATP activation of TRPV4‐EC channels. Resting RVSP and PAP were elevated in Cav‐1EC−/− and TRPV4EC−/− mice supporting the concept that Cav‐1EC‐TRPV4EC signaling lowers resting PAP. Moreover, exposure to chronic hypoxia (CH, 3 weeks) resulted in higher increases in RVSPs in Cav‐1EC−/− and TRPV4EC−/− mice when compared to the respective wild‐type control mice, suggesting that Cav‐1EC‐TRPV4EC channel signaling is protective against CH‐induced PH. We further used two well‐established models of PH— CH and sugen 5416 injection + CH. TRPV4EC channel activity, and ATP‐ and PKC‐activation of TRPV4EC channels were impaired in PAs from both the models of PH, suggesting that Cav‐1EC‐PKC‐TRPV4EC signaling may be impaired in PH. Taken together, these results suggest that Cav‐1EC‐PKC‐TRPV4EC signaling lowers resting PAP, and is impaired in PH. Deciphering the mechanisms that impair the Cav‐1EC‐PKC‐TRPV4EC signaling in PH may lead to novel therapeutic strategies to restore endothelium‐dependent vasodilation in PH.Support or Funding InformationHL121484‐01, HL‐138496