Pulmonary Arterial Hypertension Induction Research Articles

Effects of Pterostilbene on Heart and Lung Oxidative Stress Parameters in 2 Experimental Models of Cardiovascular Disease: Myocardial Infarction and Pulmonary Arterial Hypertension.

Myocardial infarction (MI) and pulmonary arterial hypertension (PAH) are 2 prevalent cardiovascular diseases. In both conditions, oxidative stress is associated with a worse prognosis. Pterostilbene (PTE), an antioxidant compound, has been studied as a possible therapy for cardiovascular diseases. This study aims to evaluate the effect of PTE on oxidative stress in the hearts of animals with MI and in the lungs of animals with PAH. Male Wistar rats were used in both models. In the MI model, the experimental groups were sham, MI, and MI + PTE. In the PAH model, the experimental groups were control, PAH, and PAH + PTE. Animals were exposed to MI through surgical ligation of the left coronary artery, or to PAH, by the administration of monocrotaline (60 mg/kg). Seven days after undergoing cardiac injury, the MI + PTE animals were treated with PTE (100 mg/kg day) for 8 days. After this, the heart was collected for molecular analysis. The PAH + PTE animals were treated with PTE (100 mg/kg day) for 14 days, beginning 7 days after PAH induction. After this, the lungs were collected for biochemical evaluation. We found that PTE administration attenuated the decrease in ejection fraction and improved left ventricle end-systolic volume in infarcted animals. In the PAH model, PTE improved pulmonary artery flow and decreased reactive oxygen species levels in the lung. PTE administration promoted protective effects in terms of oxidative stress in 2 experimental models of cardiac diseases: MI and PAH. PTE also improved cardiac function in infarcted rats and pulmonary artery flow in animals with PAH.

Sulforaphane improves redox homeostasis and right ventricular contractility in a model of pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is characterized by increased pulmonary vascular resistance, imposing overload on the right ventricle (RV) and imbalance of redox state. Our study investigated the influence of treatment with sulforaphane (SFN), found in cruciferous vegetables, on right ventricle (RV) remodeling and redox homeostasis in monocrotaline-induced pulmonary arterial hypertension (PAH). Male Wistar rats were separated into four groups: control (CTR); control + sulforaphane (CTR + SFN); monocrotaline (MCT); monocrotaline + sulforaphane (MCT + SFN). PAH induction was implemented by a single dose of MCT (60 mg/kg i.p.). Treatment with SFN (2.5 mg/kg/day i.p.) started on the 7th day after the MCT injection and persisted for 2 weeks. After 21 days of PAH induction, echocardiography, hemodynamic, and oxidative stress evaluation were performed. MCT group showed increase in RV hypertrophy, RV systolic area, RV systolic, mean pulmonary artery pressure (mPAP), and pulmonary vascular resistance (PVR), while exhibited a decrease in RV outflow tract AT/ET ratio, RV fractional shortening and tricuspid annular plane systolic excursion (TAPSE) compared to CTR (P<0.05). SFN-treated PAH attenuated detrimental changes in TPSE, mPAP, and PVR parameters. Catalase and GSH/GSSG ratio were diminished in MCT compared to CTR (P<0.05). SFN increased catalase and normalized GSH/GSSG ratio to control levels (P<0.05). Data express a benefit of SFN treatment on the cardiac function of rats with PAH associated with the cellular redox state.

Effect of Nicorandil on Endothelial Markers and Tissue Remodeling in Pulmonary Arterial Hypertension Model of Male Rats

Background: Chronic pulmonary arterial hypertension (PAH) is a rare, long-lasting illness that makes pulmonary artery endothelial cells (PAEC) not work properly and leads to heart failure and death. Objective: To evaluate the effect of nicorandil in the treatment of PAH compared to tadalafil in a rat model of monocrotaline-induced PAH. Methods: Monocrotaline injection (60 mg/kg) was used for the induction of PAH in male rats; healthy control and induction groups were not treated. The other 4 groups were treated with either nicorandil or tadalafil with or without treatment blockers (glimepiride and N-Nitroarginine methyl ester (L-NAME)) for 21 days orally. Serum was obtained for assessment of endothelin-1 (ET-1) and tissue harvested for nuclear factor kappa B (NFκB) by ELISA, western blot analysis of endothelial nitric oxide synthase (eNOS), and an apoptosis assay to examine the endothelial function. Results: Nicorandil showed a significant reduction in ET-1 and significant elevation in eNOS compared to the induction group, with comparable efficacy to tadalafil; blocker groups showed significantly elevated levels of ET-1 and reduced levels of eNOS compared to healthy control; NFκB was significantly inhibited in nicorandil and tadalafil groups and significantly elevated in blocker and induction groups; while in the TUNEL apoptosis assay, nicorandil showed the highest level of inhibition to apoptosis with apparently normal endothelium lining. Conclusions: Nicorandil shows anti-inflammatory, antiapoptotic, and enhanced endothelial morphology and function compared to the induction model.

Pulmonary Arterial Hypertension Attenuates Vasoconstrictor Responses Caused by Activation of Alpha-1-Adrenoreceptors in the Systemic Circulation

Pulmonary arterial hypertension (PAH) accompanied by an arterial pressure increase in the pulmonary circulation, remodeling of pulmonary arteries and a change in its sensitivity to regulatory factors; PAH is accompanied by activation of the sympathetic nervous system and renin-angiotensin-aldosterone system and increased production of atrial natriuretic peptide. The change in the sensitivity of the vessels of the systemic circulation (SC) to regulatory influences in PAH has not been investigated. Vasoconstrictor reactions in SC with monocrotaline (MCT) were studied in the work models of PAH in rats (Wistar, 350 ± 50 g, 4 months). Mean arterial pressure (MAP) was recorded against the background of a double autonomous blockade with the administration of the α1-adrenergic receptor agonist (α1-AR) phenylephrine (PE) to conscious rats at the start of experiment, then 2 and 4 weeks after the induction of PAH with MCT or saline injection for control animals. Registration of MAP under the action of PE was also performed during angiotensin-II (ATII) infusion. The maximal amplitude (Amax) of the change in MAP and the longest half-return time of MAP (T∆MAP1/2) to the baseline level in rats in response to the Phe injection were estimated. It was found that in response to PE, Amah did not change in rats with PAH, whereas in control animals it significantly increased. In rats with PAH 2 (n = 6) and 4 weeks after the induction of PAH with MCT, T∆MAP1/2 is significantly less than in control rats. ATII leads to delayed changes in T∆MAP1/2 in both control rats and rats with PAH. In rats with MAP, the potentiation with angiotensin T∆MAP1/2 is significantly less than in control rats. Thus, in animals with PAH, the ability of the resistive arteries of the systemic circulation to maintain tone in response to the activation of α1-AR decreases. In addition, PAH suppresses the ability of ATII to stimulate sympathetic responses in the SC. Firstly, in vivo, it has been demonstrated remodeling and changing the functional state of the pulmonary circulation leads to changes in the regulation of vascular tone of the systemic circulation.

Transpulmonary amino acid metabolism in the sugen hypoxia model of pulmonary hypertension

Background: Pulmonary arterial hypertension (PAH) is characterized by narrowing of the pulmonary arteries, endothelial cell dysfunction, and an increased vascular cell proliferation. Increased proliferation is also accompanied by glycolytic shift, where glucose is shunted towards anaerobic respiration and production of critical macromolecules. This decreases the available glucose that can be used as a fuel in the tricarboxylic acid (TCA) cycle. To compensate for the lack of TCA cycle metabolites, there is an increase in the use of non-glucose fuels - such as amino acids and fatty acids. However, the effect of this shift on other metabolic pathways is still unknown. In this study, we investigated the levels of metabolites across the pulmonary circulation to define the metabolic shift that cells undergo during PAH. Material &amp; Methods: We carried out metabolomic analysis on serum samples taken from the right and left ventricles (RV and LV) of rats with PAH (SU5416/Hypoxia model: SuHx) and normoxic controls. We also isolated MVECs from each group and performed both targeted and untargeted metabolomics on the cell lysates. Results: Induction of PAH resulted in increased pulmonary artery pressures and RV hypertrophy. Metabolomics of the RV serum were different in PAH versus control rats. This was driven by lower metabolite levels of several amino acids, including glutamine, phenylalanine, and valine. Normoxia- and SuHx-MVEC lysates samples were also distinct, with increased levels of lactic acid contributing significantly to the differences between animals with PAH and controls. Importantly, and in contrast to the serum, where glutamine levels were decreased, we observed increased levels of intracellular glutamine in our analysis. Similarly, intracellular levels of amino acids like phenylalanine, tyrosine and leucine were increased in these lysates. This also contrasted with the serum, where levels of these amino acids were decreased. Interestingly, LV levels of amino acids like valine, glutamine and lysine were similar in normoxic and SuHx samples. However, we did observe increased citrulline levels in SuHx LV serum samples. Comparing the LV/RV ratio in our samples revealed that increased oxidized glutathione was a major determinant of the difference between the SuHx and control groups. Conclusion: Our data suggests that decreased RV serum levels of amino acids in SuHx rats may be driven by increased consumption in the pulmonary vasculature. Given that glutamine levels in the RV are decreased, while being increased intracellularly in MVECs, we hypothesize that glutamine consumption in the lung microvasculature may be driven in part, to produce reduced glutathione. This is also supported by the oxidized glutathione gradient across the pulmonary vasculature in our experiments. These results provide the basis for a mechanistic study aimed at understanding how interrupting glutathione and/or branched-chain amino acid metabolism in MVECs contributes to PAH. NHLBI grant K08HL145132 (J.S.), NHLBI grant R01HL148112 01 (L.S), NHLBI grant R01HL151530 (K.S) 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.

Pharmacological effects of a new soluble guanylate cyclase stimulator in experimental pulmonary arterial hypertension

Aim. To assess the effect of an indolinone derivative (2-[2-[(5RS)-5-(hydroxymethyl)-3-methyl-1,3-oxazolidine-2yliden]-2-cyanoethylidene]-1H-indole-3(2H)-one (codename – GRS) on right ventricular contractility, endothelial vasodilator function, and histologic changes in the lungs and heart in a rat model of monocrotaline-induced pulmonary hypertension.Materials and methods. Pulmonary arterial hypertension (PAH) was induced in Wistar rats by a single subcutaneous administration of monocrotaline at a dose of 60 mg / kg. Starting from day 15 after PAH induction, the rats received either GRS at a dose of 10 mg / kg or riociguat at a dose of 1 mg / kg orally once a day. Blood pressure in the right ventricle, right ventricular weight, endothelial vasodilator function, and the histologic structure of the lungs and heart were studied after the last administration of test substances.Results. Twenty-eight days after monocrotaline administration, the rats developed PAH, as shown by the increase in the maximal blood pressure in the right ventricle and the right ventricular weight / total heart weight ratio. GRS after multiple administration reduced the maximal blood pressure in the right ventricle, had no significant effect on its contractility, improved endothelial vasodilator function, and normalized blood pressure. Riociguat had a hypotensive effect and did not alleviate endothelial dysfunction in experimental PAH.Conclusion. The indolinone derivative GRS and riociguat, both soluble guanylate cyclase stimulators, lowered blood pressure in the right ventricle. GRS also alleviated endothelial dysfunction in animals with experimental PAH.

Jagged/Notch proteins promote endothelial-mesenchymal transition-mediated pulmonary arterial hypertension via upregulation of the expression of GATAs.

This study tested the hypothesis that Jagged2/Notches promoted the endothelial-mesenchymal transition (endMT)-mediated pulmonary arterial hypertension (PAH) (i.e. induction by monocrotaline [MCT]/63 mg/kg/subcutaneous injection) through increasing the expression of GATA-binding factors which were inhibited by propylthiouracil (PTU) (i.e. 0.1% in water for daily drinking since Day 5 after PAH induction) in rodent. As compared with the control (i.e. HUVECs), the protein expressions of GATAs (3/4/6) and endMT markers (Snail/Zeb1/N-cadherin/vimentin/fibronectin/α-SMA/p-Smad2) were significantly reduced, whereas the endothelial-phenotype markers (CD31/E-cadherin) were significantly increased in silenced JAG2 gene or in silenced GATA3 gene of HUVECs (all p < 0.001). As compared with the control, the protein expressions of intercellular signallings (GATAs [3/4/6], Jagged1/2, notch1/2 and Snail/Zeb1/N-cadherin/vimentin/fibronectin/α-SMA/p-Smad2) were significantly upregulated in TGF-ß/monocrotaline-treated HUVECs that were significantly reversed by PTU treatment (all p < 0.001). By Day 42, the results of animal study demonstrated that the right-ventricular systolic-blood-pressure (RVSBP), RV weight (RVW) and lung injury/fibrotic scores were significantly increased in MCT group than sham-control (SC) that were reversed in MCT + PTU groups, whereas arterial oxygen saturation (%) and vasorelaxation/nitric oxide production of PA exhibited an opposite pattern of RVW among the groups (all p < 0.0001). The protein expressions of hypertrophic (ß-MHC)/pressure-overload (BNP)/oxidative-stress (NOX-1/NOX-2) biomarkers in RV and the protein expressions of intercellular signalling (GATAs3/4/6, Jagged1/2, notch1/2) and endMT markers (Snail/Zeb1/N-cadherin/vimentin/fibronectin/TGF-ß/α-SMA/p-Smad2) in lung parenchyma displayed an identical pattern of RVW among the groups (all p < 0.0001). Jagged-Notch-GATAs signalling, endMT markers and RVSBP that were increased in PAH were suppressed by PTU.

Beneficial effects of berberine against pulmonary complications of experimental pulmonary arterial hypertension in rats and some relevant mechanisms

Pulmonary arterial hypertension (PAH) is a severe disease that leads to pulmonary vascular remodeling characterized by a rise in pulmonary vascular resistance and pressure. We assessed the effects of an herbal compound, berberine (BB), and some related mechanisms on PAH in rats. Male Wistar rats were assigned to seven groups: control, monocrotaline (MCT), MCT+vehicle, and MCT+BB (with doses of 10, 20, 30, and 40 mg/kg) groups. Three weeks after induction of PAH by MCT, treatment groups received daily intraperitoneal injections of vehicle or BB for 3 weeks. On Day 43, the right ventricular systolic pressure (RVSP, as an index of pulmonary arterial pressure) and the ratio of RV to LV+septum weight (as RV hypertrophy index, right ventricle hypertrophy [RHVI]) were measured. Inflammatory and oxidative stress indices and histopathology of the lungs were also assessed. RVSP (89.4 ± 8.2 vs. 23 ± 3.3), RVHI (0.63 ± 0.08 vs. 0.26 ± 0.04), and lung inflammatory cytokines TNF-α (2.03 ± 0.25 vs. 1.21 ± 0.3) and IL-6 (8.8 ± 0.59 vs. 6.3 ± 0.95) significantly increased in the MCT group compared to the control group. MCT also raised the level of Malondialdehyde (0.11 ± 0.01 vs. 0.09 ± 0.01) and diminished total antioxidant capacity (6.5 ± 0.51 vs. 8.3 ± 0.62), the activity of superoxide dismutase (1.19 ± 0.22 vs. 1.93 ± 0.2), glutathione peroxidase (0.02 ± 0.002 vs. 0.03 ± 0.005), catalase (2.1 ± 0.29 vs. 2.8 ± 0.20) and Bax/Bcl-2 ratio (0.41 ± 0.07 vs. 0.61 ± 0.09) in the lungs. Treatment with BB significantly recovered all of these alterations. BB ameliorated pulmonary vascular remodeling by decreasing inflammation and fibrosis and increasing apoptosis and antioxidant/oxidant balance. Therefore, this herbal derivative may be considered a therapeutic goal against PAH.

Stabilization of RyR2 maintains right ventricular function, reduces the development of ventricular arrhythmias, and improves prognosis in pulmonary hypertension.

Right ventricular (RV) dysfunction and its associated arrhythmias are recognized as important determinants of the prognosis of pulmonary arterial hypertension (PAH). Here, we aimed to investigate whether direct pharmacological intervention in the RV muscle with dantrolene (DAN), a stabilizer of the cardiac ryanodine receptor (RyR2), has a protective effect against RV dysfunction and arrhythmia in a monocrotaline (MCT)-induced PAH rat model. Male 8-week-old Sprague-Dawley rats were injected with MCT for the induction of PAH. Induction of ventricular tachycardia (VT) by catecholamines was also evaluated in association with RyR2-mediated Ca2+ release properties in isolated cardiomyocytes. A pulmonary artery-banding model has also been established to assess the independent effects of chronic pressure overload on RV morphology and function. In the MCT-induced PAH rat model, RV hypertrophy, dilation, and functional decline were observed, with a survival rate of 0% 2 months after MCT induction. In contrast, chronic DAN treatment improved all these RV parameters and increased survival by 80%. Chronic DAN treatment also prevented the dissociation of calmodulin from RyR2, thereby inhibiting Ca2+ sparks and spontaneous Ca2+ transients in MCT-induced hypertrophied RV cardiomyocytes. Epinephrine induced VT in more than 50% of rats with MCT-induced PAH, but complete suppression of VT was achieved by chronic DAN treatment. Stabilization of RyR2 by DAN has potential as a new therapeutic agent against the development of RV dysfunction and fatal arrhythmia associated with PAH.

Sulforaphane Does Not Protect Right Ventricular Systolic and Diastolic Functions in Nrf2 Knockout Pulmonary Artery Hypertension Mice.

PurposeNrf2 is a nuclear transcription factor and plays an important role in the regulation of oxidative stress and inflammation. We recently demonstrated that sulforaphane (SFN) protected mice from developing pulmonary arterial hypertension (PAH) and right ventricular (RV) dysfunction by elevating cardiac Nrf2 expression and function. Here we further investigate Nrf2 dependence for SFN-mediated prevention of PAH and RV dysfunction in an Nrf2 knockout mouse model.MethodsWe used male global Nrf2-knockout mice and male C57/6 J wild type mice in the following groups: Control group received room air and vehicle control; SuHx group received SU5416 and 10% hypoxia for 4 weeks to induce PAH; SuHx+SFN group received both SuHx and sulforaphane, a Nrf2 activator, for 4 weeks. Transthoracic echocardiography was performed to quantify RV function and estimate pulmonary vascular resistance over 4 weeks. PAH was confirmed using invasive RV systolic pressure measurement at 4 weeks.ResultsAll Nrf2 knockout mice survived the 4-week SuHx induction of PAH. SuHx caused progressive RV diastolic/systolic dysfunction and increased RV systolic pressure. The development of RV diastolic dysfunction occurred earlier in the Nrf2 knockout PAH mice when compared with the wide type PAH mice. SFN partially or completely reversed SuHx-induced RV diastolic/systolic dysfunction and increased RV systolic pressure in wild-type mice, but not in Nrf2 knockout mice.ConclusionOur findings demonstrated the essential role of Nrf2 in SFN-mediated prevention of RV dysfunction and PAH, and increasing Nrf2 activity in patients with PAH may have therapeutic potential.

Thoracic bilateral sympathectomy attenuates oxidative stress and prevents ventricular remodelling in experimental pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a cardiopulmonary disease that affects the pulmonary vasculature, leading to increased afterload and eventually right ventricular (RV) remodelling and failure. Bilateral sympathectomy (BS) has shown promising results in dampening cardiac remodelling and dysfunction in several heart failure models. In the present study, we investigated whether BS reduces pulmonary arterial remodelling and mitigates RV remodelling and failure. PAH was induced in male Wistar rats by intraperitoneal injection of monocrotaline. Rats were divided into 3 groups, involving untreated PAH (n = 15), BS-treated PAH (n = 13) and non-manipulated control rats (n = 13). Three weeks after PAH induction, the rats were anaesthetized and RV function was assessed via the pressure-volume loop catheter approach. Upon completion of the experiment, the lungs and heart were harvested for further analyses. BS was found to prevent pulmonary artery remodelling, with a clear reduction in α-smooth muscle actin and endothelin-1 expression. RV end-systolic pressure was reduced in the BS group, and preload recruitable stroke work was preserved. BS, therefore, mitigated RV remodelling and cardiomyocyte hypertrophy and diminished oxidative stress. We showed that thoracic BS may be an important treatment option for PAH patients. Blockade of the sympathetic pathway can prevent pulmonary remodelling and protect the RV from oxidative stress, myocardial remodelling and function decay.

Pulmonary and Systemic Hemodynamics following Multielectrode Radiofrequency Catheter Renal Denervation in Acutely Induced Pulmonary Arterial Hypertension in Swine.

Objective We aimed to assess the effects of renal denervation (RDN) on systemic and pulmonary hemodynamics in a swine model of thromboxane A2- (TXA2-) induced pulmonary arterial hypertension (PAH). Methods The study protocol comprised two PAH inductions with a target mean pulmonary artery pressure (PAP) of 40 mmHg at baseline and following either the RDN or sham procedure. Ten Landrace pigs underwent the first PAH induction; then, nine animals were randomly allocated in 1 : 1 ratio to RDN or sham procedure; the second PAH induction was performed in eight animals (one animal died of pulmonary embolism during the first PAH induction, and one animal died after RDN). In the RDN group, ablation was performed in all available renal arteries, and balloon inflation within artery branches was performed in controls. An autopsy study of the renal arteries was performed. Results At baseline, the target mean PAP was achieved in all animals with 25.0 [20.1; 25.2] mcg of TXA2. The second PAH induction required the same mean TXA2 dose and infusion time. There was no statistically significant difference in the mean PAP at second PAH induction between the groups (39.0 ± 5.3 vs. 39.75 ± 0.5 mmHg, P > 0.05). In the RDN group, the second PAH induction resulted in a numerical but insignificant trend toward a decrease in the mean systemic blood pressure and systemic vascular resistance, when compared with the baseline induction (74 ± 18.7 vs. 90.25 ± 28.1 mmHg and 1995.3 ± 494.3 vs. 2433.7 ± 1176.7 dyn∗sec∗cm−5, P > 0.05, respectively). No difference in hemodynamic parameters was noted in the sham group between the first and second PAH induction. Autopsy demonstrated artery damage in both groups, but RDN resulted in more severe lesions. Conclusions According to our results, RDN does not result in significant acute pulmonary or systemic hemodynamic changes in the TXA2-induced PAH model. The potential chronic effects of RDN on PAH require further research.

Naringin Ameliorates Monocrotaline-Induced Pulmonary Arterial Hypertension Through Endothelial-To-Mesenchymal Transition Inhibition.

Pulmonary arterial hypertension (PAH) caused by enhanced arterial pressure increases vessel resistance in the lung. Endothelial-to-mesenchymal transition (EndMT) plays key roles in the vascular remodeling in PAH. Naringin, a protective gaseous mediator is commonly extracted from tomatoes and citrus fruits (such as grapefruits), and demonstrates anti-inflammation, anti-oxidant, anti-proliferation, and anti-tumor effects. Meanwhile, the association of Naringin and the process of EndMT is still unclear. In this study, monocrotaline (MCT) administration (60 mg/kg) was delivered for the induction of PAH in rats. Following this, Naringin (concentrations: 25, 50, and 100 mg/kg/day) was used for treatments. Human Umbilical Vein Endothelial Cells (HUVECs) were stimulated with Naringin and transforming growth factor β1 (TGFβ1, 10 ng/ml). As the result, Naringin was demonstrated to inhibit EndMT and alleviate PAH progression. In particular, in HUVECs, Naringin significantly suppressed the mesenchymal marker expression induced by TGFβ1 treatment, enhanced the endothelial marker expression, and inhibited the activation of ERK and NF-κB signaling pathways. To conclude, this study provided novel evidence suggesting the beneficial effects of Naringin in PAH through the inhibition of the ERK and NF-κB signaling pathways and the EndMT progression in pulmonary arteries.

PHARMACOLOGIC ACTIVATION OF THE ALTERNATIVE RAS ATTENUATES DEVELOPMENT OF PULMONARY ARTERIAL HYPERTENSION IN MONOCROTALINE TREATED RATS

Objective: Pulmonary arterial hypertension (PAH) is a rare, chronic and debilitating disease characterized by increased pulmonary arterial pressure leading to right heart failure and – eventually death. Several drugs are approved for the treatment of PAH, but due to ongoing disease progression only half of the patients survive more than 7 years after diagnosis. A novel therapeutic approach based on pharmacologic activation of the alternative RAS was investigated in monocrotaline induced PAH in rats. Design and method: PAH was induced in 12 week-old Wistar rats by an injection of monocrotaline (60 mg/kg). Immediately after PAH induction, the rats (n = 11-12 in each group) were treated for 4 weeks with either a) vehicle, b) the novel peptidase inhibitor ALT001, or c) the endothelin receptor antagonist bosentan – representing the standard of care. Vehicle-treated sham rats served as healthy controls. Analysis included tissue and plasma equilibrium levels of angiotensin metabolites, echocardiography determined right ventricular function and structure, pulmonary arterial pressure, systemic blood pressure and histomorphometrical evaluations. Results: Ang II was significantly increased in lungs of monocrotaline treated animals concomitant with a profound increase in pulmonary arterial pressure (mPAP), reduced fractional shortening, dilated pulmonary valve diameter and a thickened and enlarged right ventricle. ALT001 treatment resulted in increased Ang 1–7 levels while Ang II levels were normalized. Bosentan treatment did not affect angiotensin peptide levels. The PAH induced increase in mPAP was almost completely abolished by ALT001 treatment, while systemic blood pressure remained unaffected. Right ventricular structure and function was effectively preserved under ALT001 treatment and pathological changes in fractional shortening (FS) were significantly reduced. Conclusions: Small molecule based modulation of the RAS might represent a promising novel therapeutic approach in treating RAS-related diseases, including PAH. (Partly supported by VEGA 1/0127/17, FFG 872313)

Pterostilbene improves cardiac function in a rat model of right heart failure through modulation of calcium handling proteins and oxidative stress.

This study explored the effect of pterostilbene (PTS) complexed with hydroxypropyl-β-cyclodextrin (HPβCD) on right heart function, glutathione and glutaredoxin systems, and the expression of redox-sensitive proteins involved with regulation calcium levels in the experimental model of pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). After 7 days of PAH induction, rats received daily doses of the PTS:HPβCD complex (corresponding to 25, 50, or 100 mg·kg-1 of PTS) or vehicle (control group, CTR0) (an aqueous solution containing HPβCD; CTR0 and MCT0 (MCT group that did not receive PTS treatment)) via oral administration for 2 weeks. The results showed that the PTS:HPβCD complex increased the content of reduced glutathione and the activity of glutathione-S-transferase and glutaredoxin in the right ventricle (RV) of MCT-treated rats in a dose-dependent manner. Additionally, at higher doses, it also prevented the reduction of stroke volume and cardiac output, prevented myocardial performance index (MPI) increase, reduced lipoperoxidation, reduced total phospholamban, and increased the expression of sarcoplasmic reticulum calcium ATPase in the RV of MCT-treated rats. These results demonstrate that the PTS:HPβCD complex has a dose-dependent antioxidant mechanism that results in improved cardiac function in experimental right heart failure. Our results open a field of possibilities to PTS administration as new therapeutic approach to conventional therapy for right ventricular dysfunction. Novelty Pterostilbene complexed with hydroxypropyl-β-cyclodextrin could be a new therapeutic approach. Pterostilbene complexed with hydroxypropyl-β-cyclodextrin reestablishes redox homeostasis through glutathione metabolism modulation, leading to an improved MPI in pulmonary arterial hypertension-provoked right heart failure.

Sulforaphane prevents right ventricular injury and reduces pulmonary vascular remodeling in pulmonary arterial hypertension.

Right ventricular (RV) dysfunction is the main determinant of mortality in patients with pulmonary arterial hypertension (PAH) and while inflammation is pathogenic in PAH, there is limited information on the role of RV inflammation in PAH. Sulforaphane (SFN), a potent Nrf2 activator, has significant anti-inflammatory effects and facilitates cardiac protection in preclinical diabetic models. Therefore, we hypothesized that SFN might play a comparable role in reducing RV and pulmonary inflammation and injury in a murine PAH model. We induced PAH using SU5416 and 10% hypoxia (SuHx) for 4 wk in male mice randomized to SFN at a daily dose of 0.5 mg/kg 5 days per week for 4 wk or to vehicle control. Transthoracic echocardiography was performed to characterize chamber-specific ventricular function during PAH induction. At 4 wk, we measured RV pressure and relevant measures of histology and protein and gene expression. SuHx induced progressive RV, but not LV, diastolic and systolic dysfunction, and RV and pulmonary remodeling, fibrosis, and inflammation. SFN prevented SuHx-induced RV dysfunction and remodeling, reduced RV inflammation and fibrosis, upregulated Nrf2 expression and its downstream gene NQO1, and reduced the inflammatory mediator leucine-rich repeat and pyrin domain-containing 3 (NLRP3). SFN also reduced SuHx-induced pulmonary vascular remodeling, inflammation, and fibrosis. SFN alone had no effect on the heart or lungs. Thus, SuHx-induced RV and pulmonary dysfunction, inflammation, and fibrosis can be attenuated or prevented by SFN, supporting the rationale for further studies to investigate SFN and the role of Nrf2 and NLRP3 pathways in preclinical and clinical PAH studies.NEW & NOTEWORTHY Pulmonary arterial hypertension (PAH) in this murine model (SU5416 + hypoxia) is associated with early changes in right ventricular (RV) diastolic and systolic function. RV and lung injury in the SU5416 + hypoxia model are associated with markers for fibrosis, inflammation, and oxidative stress. Sulforaphane (SFN) alone for 4 wk has no effect on the murine heart or lungs. Sulforaphane (SFN) attenuates or prevents the RV and lung injury in the SUF5416 + hypoxia model of PAH, suggesting that Nrf2 may be a candidate target for strategies to prevent or reverse PAH.

Upregulation of miR-335-3p by NF-κB Transcriptional Regulation Contributes to the Induction of Pulmonary Arterial Hypertension via APJ during Hypoxia.

Pulmonary arterial hypertension (PAH) is a cardiopulmonary disease that can lead to heart failure and eventually death. MicroRNAs (miRs) play essential roles during PAH progression; however, their exact mechanism of action remains unclear. Apelin is a small bioactive peptide with a key protective function in the pathogenesis of PAH mediated by binding to the APJ gene. The aim of the present study was to investigate the role of miR-335-3p in chronic normobaric hypoxia (CNH)-induced PAH in mice and the potential underlying regulatory mechanism. Adult male C57BL/6 mice were exposed to normoxia (~21% O2) or CNH (~10% O2, 23 h/d) for 5 weeks. MiR-335-3p was significantly increased in lung tissue of CNH-induced PAH mice. Blocking miR-335-3p attenuated CNH-induced PAH and alleviated pulmonary vascular remodeling. Bioinformatics analysis and luciferase reporter assay indicated that nuclear factor-kappa beta (NF-κB) acted as a transcriptional regulator upstream of miR-335-3p. Pyrrolidine dithiocarbamate treatment reversed the CNH-induced increase in miR-335-3p expression and diminished CNH-induced PAH. Moreover, p50-/- mice were resistant to CNH-induced PAH. Finally, APJ was identified as a direct targeting gene downstream of miR-335-3p, and pharmacological activation of APJ by its ligand apelin-13 reduced CNH-induced PAH and improved pulmonary vascular remodeling. Our results indicate that NF-κB-mediated transcriptional upregulation of miR-335-3p contributes to the inhibition of APJ and induction of PAH during hypoxia; hence, miR-335-3p could be a potential therapeutic target for hypoxic PAH.

Chrysin ameliorates ANTU-induced pulmonary edema and pulmonary arterial hypertension via modulation of VEGF and eNOs.

Alpha-naphthylthiourea (ANTU), a rodenticide induces lung toxicity. Chrysin a flavonoid possesses antioxidant, anti-inflammatory, and antihypertensive potential. The aim of this study was to evaluate the efficacy of chrysin against ANTU-induced pulmonary edema (PE) and pulmonary arterial hypertension (PAH) in laboratory rats. Sprague-Dawley rats were used to inducePE (ANTU, 10 mg/kg, ip) and PAH (ANTU, 5 mg/kg, ip, 4 weeks). Animals were treated with chrysin (10, 20, and 40 mg/kg) and various biochemical, molecular, and histological parameters were evaluated. Acute administration of ANTU induces PE revealed by significant (P < 0.05) increasein relative lung weight, pleural effusion volume, lung edema, bronchoalveolar lavage fluid cell counts, total protein, 5-hydroxytryptamine (5-HT), lactate dehydrogenase (LDH), and γ-glutamyl transferase (GGT), whereas pretreatment with chrysin (20 and 40 mg/kg, ip) significantly (P < 0.05) attenuated these ANTU-induced biochemical and histological alterations. Repeated administration of ANTU caused induction of PAH evaluated by significant (P < 0.05) alterations in electrocardiographic, hemodynamic changes, and left ventricular function, whereas chrysin (20 and 40 mg/kg, p.o.) treatment significantly (P < 0.05) attenuated these alterations. ANTU-induced hematological and serum biochemical (aspartate transaminase, alanine transaminase, LDH, and creatinine kinase MB) alterations were significantly (P < 0.05) inhibited by chrysin. It also significantly (P < 0.05) decreased elevated levels of oxido-nitrosative stress in the right ventricle (RV) and lung. Chrysin significantly (P < 0.05) attenuated downregulated endothelial nitric oxide synthase and upregulated vascular endothelial growth factor messenger RNA and protein expressions both in the RV and pulmonary artery. Chrysin inhibited ANTU-induced PE and PAH via modulation of inflammatory responses (5-HT, LDH, and GGT), oxido-nitrosative stress, and VEGF and eNOs levels.

Caffeic Acid Phenethyl Ester Rescues Pulmonary Arterial Hypertension through the Inhibition of AKT/ERK-Dependent PDGF/HIF-1α In Vitro and In Vivo.

Pulmonary arterial hypertension (PAH) is characterized by pulmonary arterial proliferation and remodeling, resulting in a specific increase in right ventricle systolic pressure (RVSP) and, ultimately right ventricular failure. Recent studies have demonstrated that caffeic acid phenethyl ester (CAPE) exerts a protective role in NF-κB-mediated inflammatory diseases. However, the effect of CAPE on PAH remains to be elucidated. In this study, monocrotaline (MCT) was used to establish PAH in rats. Two weeks after the induction of PAH by MCT, CAPE was administrated by intraperitoneal injection once a day for two weeks. Pulmonary hemodynamic measurements and pulmonary artery morphological assessments were examined. Our results showed that administration of CAPE significantly suppressed MCT-induced vascular remodeling by decreasing the HIF-1α expression and PDGF-BB production, and improved in vivo RV systolic performance in rats. Furthermore, CAPE inhibits hypoxia- and PDGF-BB-induced HIF-1α expression by decreasing the activation of the AKT/ERK pathway, which results in the inhibition of human pulmonary artery smooth muscle cells (hPASMCs) proliferation and prevention of cells resistant to apoptosis. Overall, our data suggest that HIF-1α is regarded as an alternative target for CAPE in addition to NF-κB, and may represent a promising therapeutic agent for the treatment of PAH diseases.

High Intensity Interval Training in a Rat Model of Severe, Angioproliferative Pulmonary Arterial Hypertension

PURPOSE: We previously demonstrated superior benefit of high intensity interval training (HIIT) over continuous exercise training (CET) in a monocrotaline rat model of mild pulmonary arterial hypertension (PAH). Here we investigate HIIT in a model that elicits a more severe, angioproliferative PAH. METHODS: SD rats (~200g, male) received Sugen5416 (20mg/kg), followed by 3 wks of hypoxia (Patm=362 mmHg) and 4 wks of room air to induce PAH (SuHx, n=33). Subgroups of SuHx then underwent 6 wks of treadmill training performed as either HIIT (2 min at ~80-90%VO2reserve [VO2R] + 3 min at 30%VO2R, for 4-5 cycles, n=12), or low intensity CET (45-60 min at 50%VO2R, n=11), with the remainder untrained (SED, n=10). Values are mean±SE. RESULTS: Mortality in SuHx was unexpectedly worse for HIIT (4 deaths at 56, 60, 68, and 71 days), vs. CET (2 deaths at 60, and 73 days), and SED (2 deaths at 66 days). While all animals had similar baseline echocardiographic measures of cardiac output (CO, in uL) and stroke volume (SV, in mL/min), SuHx that died prematurely (n=8) had greater impairment in CO (141±19) and SV (424±52) following PAH induction (at pre-training) compared to surviving SuHx (n=25, 235±26, 598±38). Final CO and SV were higher for both HIIT (239±49, 540±58) and CET (207±41, 529±51) vs. SED (122±12, 405±35) SuHx rats, and were similar to untrained healthy controls (CON, n=6, 268±59, 548±71). SuHx-induced elevation in right ventricular (RV) systolic pressure (mmHg) and RV hypertrophy (as RV mass/LV+septum mass, and as RV thickness on echo in mm) were not improved by training with HIIT (61±7; 0.60±0.07, 2.2±0.2) or CET (60±8; 0.47±0.04, 2.0±0.2), vs. SED (55±8; 0.52±0.06, 2.2±0.2), and were higher than CON (28±3; 0.24±0.01, 1.3±0.1). Final VO2max (ml/kg/min) in SuHx was also not improved for either HIIT (44±1.9) or CET (46±1.7) vs. SED (46±3.8). CONCLUSION: Both HIIT and CET promoted better RV function in SuHx rats despite no amelioration of RV hypertrophy, PAH, or exercise impairment. However, in contrast to previous findings in a mild PAH rat model, exercise training, particularly with HIIT, increased mortality for animals with poorer cardiac function prior to training onset and suggests that further investigation is needed to optimize training approach for patients with more severe RV dysfunction. Funding: NIH-NHLBI R-15 (to MB Brown).