semaxinib and Hypertrophy--Right-Ventricular

Pulmonary hypertension (PH) seriously affects the health of patients. We have found in clinical studies that PH has adverse effects on both maternal and offspring.. To establish a animal model of PH induced by hypoxia/SU5416 and observe the effects of PH on pregnant mice and their fetuses.. Twenty-four C57 mice aged 7-9 weeks were selected and divided into 4 groups with 6 mice in each group. ① Female mice with normal oxygen; ② Female mice with hypoxia/SU5416; ③ Pregnant mice with normal oxygen; ④ Pregnant mice with hypoxia/SU5416. After 19 days, weight, right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) were compared in each group. Lung tissue and right ventricular blood were collected. The number and weight of fetal mice were also compared between the two pregnant groups.. There was no significant difference in RVSP and RVHI between female and pregnant mice under the same condition. Compared with normal oxygen condition, two groups of mice in hypoxia/SU5416 had poor development, RVSP and RVHI were significantly increased, the number of fetal mice was small, hypoplasia, degeneration and even abortion.. The model of mice PH was successfully established. PH affects the development and health of female and pregnant mice, and seriously affects the fetuses.

Topics: Animals; Disease Models, Animal; Female; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Mice; Oxygen; Pregnancy; Pulmonary Artery

Monoamine oxidases (MAOs), a class of enzymes bound to the outer mitochondrial membrane, are important sources of reactive oxygen species. Increased MAO-A activity in endothelial cells and cardiomyocytes contributes to vascular dysfunction and progression of left heart failure. We hypothesized that inhibition of MAO-A can be used to treat pulmonary arterial hypertension (PAH) and right ventricular (RV) failure. MAO-A levels in lung and RV samples from patients with PAH were compared with levels in samples from donors without PAH. Experimental PAH was induced in male Sprague-Dawley rats by using Sugen 5416 and hypoxia (SuHx), and RV failure was induced in male Wistar rats by using pulmonary trunk banding (PTB). Animals were randomized to receive either saline or the MAO-A inhibitor clorgyline at 10 mg/kg. Echocardiography and RV catheterization were performed, and heart and lung tissues were collected for further analysis. We found increased MAO-A expression in the pulmonary vasculature of patients with PAH and in experimental experimental PAH induced by SuHx. Cardiac MAO-A expression and activity was increased in SuHx- and PTB-induced RV failure. Clorgyline treatment reduced RV afterload and pulmonary vascular remodeling in SuHx rats through reduced pulmonary vascular proliferation and oxidative stress. Moreover, clorgyline improved RV stiffness and relaxation and reversed RV hypertrophy in SuHx rats. In PTB rats, clorgyline had no direct clorgyline had no direct effect on the right ventricle effect. Our study reveals the role of MAO-A in the progression of PAH. Collectively, these findings indicated that MAO-A may be involved in pulmonary vascular remodeling and consecutive RV failure.

Topics: Animals; Clorgyline; Disease Models, Animal; Disease Progression; Heart Ventricles; Humans; Hypertrophy, Right Ventricular; Indoles; Monoamine Oxidase; Oxidative Stress; Pulmonary Arterial Hypertension; Pulmonary Artery; Pyrroles; Rats; Vascular Remodeling; Vascular Stiffness; Vasodilation

Pulmonary hypertension (PH) causes cardiac hypertrophy in the right ventricle (RV) and eventually leads to RV failure due to persistently elevated ventricular afterload. We hypothesized that the mechanical stress on the RV associated with increased afterload impairs vasodilator function of the right coronary artery (RCA) in PH. Coronary vascular response was assessed using microangiography with synchrotron radiation (SR) in two well-established PH rat models, monocrotaline injection or the combined exposure to chronic hypoxia and vascular endothelial growth factor receptor blockade with Su5416 (SuHx model). In the SuHx model, the effect of the treatment with the nonselective endothelin-1 receptor antagonist (ERA), macitentan, was also examined. Myocardial viability was determined in SuHx model rats, using

Topics: Animals; Antihypertensive Agents; Coronary Angiography; Coronary Vessels; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Monocrotaline; Predictive Value of Tests; Pulmonary Arterial Hypertension; Pyrimidines; Pyrroles; Rats, Sprague-Dawley; Severity of Illness Index; Sulfonamides; Synchrotrons; Vasodilation; Ventricular Dysfunction, Right; Ventricular Function, Right; Ventricular Remodeling

It is generally considered that there is an increase in glycolysis in the hypertrophied right ventricle (RV) during pulmonary hypertension (PH), which leads to a decrease in glucose oxidation through the tricarboxylic acid (TCA) cycle. Although recent studies have demonstrated that fatty acid (FA) and glucose accumulated in the RV of patients with PH, the details of this remain to be elucidated. The purpose of the current study was to assess the metabolic remodeling in the RV of rats with PH using a metabolic analysis. Male rats were treated with the vascular endothelial growth factor receptor blocker SU5416 followed by 3 weeks of hypoxic conditions and 5 weeks of normoxic conditions (Su/Hx rats). Hemodynamic measurements were conducted, and the RV was harvested for the measurement of metabolites. A metabolomics analysis revealed a decreasing trend in the levels of alanine, argininosuccinic acid and downstream TCA cycle intermediates, including fumaric and malic acid and an increasing trend in branched‑chain amino acids (BCAAs) in Su/Hx rats compared with the controls; however, no trends in glycolysis were indicated. The FA metabolomics analysis also revealed a decreasing trend in the levels of long‑chain acylcarnitines, which transport FA from the cytosol to the mitochondria and are essential for beta‑oxidation. The current study demonstrated that the TCA cycle was less activated because of a decreasing trend in the expression of fumaric acid and malic acid, which might be attributable to the expression of adenylosuccinic acid and argininosuccinic acid. These results suggest that dysregulated BCAA metabolism and a decrease in FA oxidation might contribute to the reduction of the TCA cycle reactions.

Topics: Animals; Citric Acid Cycle; Fatty Acids; Glucose; Heart Ventricles; Humans; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Oxidation-Reduction; Pulmonary Arterial Hypertension; Pyrroles; Rats; Rats, Sprague-Dawley; Ventricular Remodeling

Pulmonary Hypertension (PH) is a pathophysiological condition, defined by a mean pulmonary arterial pressure exceeding 25 mm Hg at rest, as assessed by right heart catheterization. A broad spectrum of diseases can lead to PH, differing in their etiology, histopathology, clinical presentation, prognosis, and response to treatment. Despite significant progress in the last years, PH remains an uncured disease. Understanding the underlying mechanisms can pave the way for the development of new therapies. Animal models are important research tools to achieve this goal. Currently, there are several models available for recapitulating PH. This protocol describes a two-hit mouse PH model. The stimuli for PH development are hypoxia and the injection of SU5416, a vascular endothelial growth factor (VEGF) receptor antagonist. Three weeks after initiation of Hypoxia/SU5416, animals develop pulmonary vascular remodeling imitating the histopathological changes observed in human PH (predominantly Group 1). Vascular remodeling in the pulmonary circulation results in the remodeling of the right ventricle (RV). The procedures for measuring RV pressures (using the open chest method), the morphometrical analyses of the RV (by dissecting and weighing both cardiac ventricles) and the histological assessments of the remodeling (both pulmonary by assessing vascular remodeling and cardiac by assessing RV cardiomyocyte hypertrophy and fibrosis) are described in detail. The advantages of this protocol are the possibility of the application both in wild type and in genetically modified mice, the relatively easy and low-cost implementation, and the quick development of the disease of interest (3 weeks). Limitations of this method are that mice do not develop a severe phenotype and PH is reversible upon return to normoxia. Prevention, as well as therapy studies, can easily be implemented in this model, without the necessity of advanced skills (as opposed to surgical rodent models).

Topics: Animals; Cell Hypoxia; Disease Models, Animal; Fibrosis; Heart Ventricles; Humans; Hydrogen-Ion Concentration; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Indoles; Male; Mice; Pulmonary Artery; Pulmonary Circulation; Pyrroles; Vascular Endothelial Growth Factor A; Vascular Remodeling; Ventricular Remodeling

Pulmonary arterial hypertension (PAH) is a lethal disease characterized by a progressive increase in pulmonary artery pressure due to an increase in vessel tone and occlusion of vessels. The endogenous vasodilator prostacyclin and its analogs are used as therapeutic agents for PAH. However, their pharmacological effects on occlusive vascular remodeling have not been elucidated yet. Selexipag is a recently approved, orally available and selective prostacyclin receptor agonist with a non-prostanoid structure. In this study, we investigated the pharmacological effects of selexipag on the pathology of chronic severe PAH in Sprague-Dawley and Fischer rat models in which PAH was induced by a combination of injection with the vascular endothelial growth factor receptor antagonist Sugen 5416 and exposure to hypoxia (SuHx). Oral administration of selexipag for three weeks significantly improved right ventricular systolic pressure and right ventricular (RV) hypertrophy in Sprague-Dawley SuHx rats. Selexipag attenuated the proportion of lung vessels with occlusive lesions and the medial wall thickness of lung arteries, corresponding to decreased numbers of Ki-67-positive cells and a reduced expression of collagen type 1 in remodeled vessels. Administration of selexipag to Fischer rats with SuHx-induced PAH reduced RV hypertrophy and mortality caused by RV failure. These effects were probably based on the potent prostacyclin receptor agonistic effect of selexipag on pulmonary vessels. Selexipag has been approved and is used in the clinical treatment of PAH worldwide. It is thought that these beneficial effects of prostacyclin receptor agonists on multiple aspects of PAH pathology contribute to the clinical outcomes in patients with PAH.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetamides; Animals; Cell Proliferation; Collagen Type I; Disease Models, Animal; Heart Ventricles; Hemodynamics; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Lung; Male; Pulmonary Arterial Hypertension; Pyrazines; Pyrroles; Rats, Sprague-Dawley; Receptors, Epoprostenol; Systole; Vascular Remodeling

Right ventricular failure (RVF) is a common cause of death in patients suffering from pulmonary arterial hypertension (PAH). The current treatment for PAH only moderately improves symptoms, and RVF ultimately occurs. Therefore, it is necessary to develop new treatment strategies to protect against right ventricle (RV) maladaptation despite PAH progression. In this study, we hypothesize that local mesenchymal stem cell (MSC) delivery via a novel bioscaffold can improve RV function despite persistent PAH. To test our hypothesis, we induced PAH in adult rats with SU5416 and chronic hypoxia exposure; treated with rat MSCs delivered by intravenous injection, intramyocardial injection, or epicardial placement of a bioscaffold; and then examined treatment effectiveness by in vivo pressure-volume measurement, echocardiography, histology, and immunohistochemistry. Our results showed that compared with other treatment groups, only the MSC-seeded bioscaffold group resulted in RV functional improvement, including restored stroke volume, cardiac output, and improved stroke work. Diastolic function indicated by end-diastolic pressure-volume relationship was improved by the local MSC treatments or bioscaffold alone. Cardiomyocyte hypertrophy and RV fibrosis were both reduced, and von Willebrand factor expression was restored by the MSC-seeded bioscaffold treatment. Overall, our study suggests a potential new regenerative therapy to rescue the pressure-overload failing RV with persistent pulmonary vascular disease, which may improve quality of life and/or survival of PAH patients. NEW & NOTEWORTHY We explored the effects of mesenchymal stem cell-seeded bioscaffold on right ventricles (RVs) of rats with established pulmonary arterial hypertension (PAH). Some beneficial effects were observed despite persistent PAH, suggesting that this may be a new therapy for RV to improve quality of life and/or survival of PAH patients.

Topics: Animals; Arterial Pressure; Cells, Cultured; Disease Models, Animal; Fibrosis; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Male; Mesenchymal Stem Cell Transplantation; Myocardial Contraction; Myocardium; Pulmonary Arterial Hypertension; Pulmonary Artery; Pyrroles; Rats, Sprague-Dawley; Recovery of Function; Regeneration; Tissue Scaffolds; Ventricular Dysfunction, Right; Ventricular Function, Right; Ventricular Remodeling; von Willebrand Factor

Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling, increased pulmonary artery (PA) pressure, right-heart afterload and death. Mechanistic target of rapamycin (mTOR) promotes smooth muscle cell proliferation, survival, and pulmonary vascular remodeling via two functionally distinct mTOR complexes (mTORCs)-1 (supports cell growth) and -2 (promotes cell survival), and dual mTORC1/mTORC2 inhibition selectively induces pulmonary arterial hypertension PA vascular smooth muscle cell apoptosis and reverses pulmonary vascular remodeling. The consequences of mTOR inhibition on right ventricle (RV) morphology and function are not known. Using SU5416/hypoxia rat model of pulmonary hypertension (PH), we report that, in contrast to activation of both mTORC1 and mTORC2 pathways in small remodeled PAs, RV tissues had predominant up-regulation of mTORC1 signaling accompanied by cardiomyocyte and RV hypertrophy, increased RV wall thickness, RV/left ventricle end-diastolic area ratio, RV contractility and afterload (arterial elastance), and shorter RV acceleration time compared with controls. Treatment with mTOR kinase inhibitor, PP242, at Weeks 6-8 after PH induction suppressed both mTORC1 and mTORC2 in small PAs, but only mTORC1 signaling in RV, preserving basal mTORC2-Akt levels. Vehicle-treated rats showed further PH and RV worsening and profound RV fibrosis. PP242 reversed pulmonary vascular remodeling and prevented neointimal occlusion of small PAs, significantly reduced PA pressure and pulmonary vascular resistance, reversed cardiomyocyte hypertrophy and RV remodeling, improved max RV contractility, arterial elastance, and RV acceleration time, and prevented development of RV fibrosis. Collectively, these data show a predominant role of mTORC1 versus mTORC2 in RV pathology, and suggest potential attractiveness of mTOR inhibition to simultaneously target pulmonary vascular remodeling and RV dysfunction in established PH.

Topics: Animals; Cell Proliferation; Cell Survival; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Indoles; Male; Myocytes, Cardiac; Protein Kinase Inhibitors; Pulmonary Artery; Pyrroles; Rats, Sprague-Dawley; TOR Serine-Threonine Kinases; Ventricular Remodeling

Pulmonary arterial hypertension (PAH) is a lethal disease and improved therapeutic strategies are needed. Increased pulmonary arterial pressure, due to vasoconstriction and vascular remodeling, causes right ventricle (RV) failure and death in patients. The treatment of Sprague-Dawley rats with SU5416 injection and exposure to chronic hypoxia for three weeks followed by maintenance in normoxia promote progressive and severe PAH with pathologic features that resemble human PAH. At 5-17 weeks after the SU5416 injection, PAH is developed with pulmonary vascular remodeling as well as RV hypertrophy and fibrosis. The present study investigated subsequent events that occur in these PAH animals.. At 35 weeks after the SU5416 injection, rats still maintained high RV pressure, but pulmonary vascular remodeling was significantly reduced. Metabolomics analysis revealed that lungs of normal rats and rats from the 35-week time point had different metabolomics profiles. Despite the maintenance of high RV pressure, fibrosis was resolved at 35-weeks. Masson's trichrome stain and Western blotting monitoring collagen 1 determined 12% fibrosis in the RV at 17-weeks, and this was decreased to 5% at 35-weeks. The level of myofibroblasts was elevated at 17-weeks and normalized at 35-weeks.. These results suggest that biological systems possess natural ways to resolve pulmonary and RV remodeling. The resolution of RV fibrosis appears to involve the reduction of myofibroblast-dependent collagen synthesis. Understanding these endogenous mechanisms should help improve therapeutic strategies to treat PAH and RV failure.

Topics: Animals; Blotting, Western; Fibrosis; Heart Ventricles; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Indoles; Lung; Male; Metabolomics; Pulmonary Artery; Pyrroles; Rats; Rats, Sprague-Dawley; Ventricular Remodeling

Prostacyclin and its analogues improve cardiac output and functional capacity in patients with pulmonary arterial hypertension (PAH); however, the underlying mechanism is not fully understood. We hypothesised that prostanoids have load-independent beneficial effects on the right ventricle (RV). Angio-obliterative PAH and RV failure were induced in rats with a single injection of SU5416 followed by 4 weeks of exposure to hypoxia. Upon confirmation of RV dysfunction and PAH, rats were randomised to 0.1 μg·kg(-1) nebulised iloprost or drug-free vehicle, three times daily for 2 weeks. RV function and treadmill running time were evaluated pre- and post-iloprost/vehicle treatment. Pulmonary artery banded rats were treated 8 weeks after surgery to allow for significant RV hypertrophy. Inhaled iloprost significantly improved tricuspid annulus plane systolic excursion and increased exercise capacity, while mean pulmonary artery pressure and the percentage of occluded pulmonary vessels remained unchanged. Rats treated with iloprost had a striking reduction in RV collagen deposition, procollagen mRNA levels and connective tissue growth factor expression in both SU5416/hypoxia and pulmonary artery banded rats. In vitro, cardiac fibroblasts treated with iloprost showed a reduction in transforming growth factor (TGF)-β1-induced connective tissue growth factor expression, in a protein kinase A-dependent manner. Iloprost decreased TGF-β1-induced procollagen mRNA expression as well as cardiac fibroblast activation and migration. Iloprost significantly induced metalloproteinase-9 gene expression and activity and increased the expression of autophagy genes associated with collagen degradation. Inhaled iloprost improves RV function and reverses established RV fibrosis partially by preventing collagen synthesis and by increasing collagen turnover.

Topics: Animals; Collagen; Cyclic AMP-Dependent Protein Kinases; Echocardiography; Fibroblasts; Fibrosis; Heart Ventricles; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Iloprost; Indoles; Male; Matrix Metalloproteinase 9; Microscopy, Phase-Contrast; Physical Conditioning, Animal; Procollagen; Pyrroles; Random Allocation; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transforming Growth Factor beta1; Vasodilator Agents; Ventricular Function, Right

The SU5416 combined with hypoxia (SuHx) rat model features angio-obliterative pulmonary hypertension resembling human pulmonary arterial hypertension. Despite increasing use of this model, a comprehensive haemodynamic characterisation in conscious rats has not been reported. We used telemetry to characterise haemodynamic responses in SuHx rats and associated these with serial histology. Right ventricular systolic pressure (RVSP) increased to a mean±sd of 106±7 mmHg in response to SuHx and decreased but remained elevated at 72±8 mmHg upon return to normoxia. Hypoxia-only exposed rats showed a similar initial increase in RVSP, a lower maximum RVSP and near-normalisation of RVSP during subsequent normoxia. Progressive vascular remodelling consisted of a four-fold increase in intima thickness, while only minimal changes in media thickness were found. The circadian range in RVSP provided an accurate longitudinal estimate of vascular remodelling. In conclusion, in SuHx rats, re-exposure to normoxia leads to a partial decrease in pulmonary artery pressure, with persisting hypertension and pulmonary vascular remodelling characterised by progressive intima obstruction.

Topics: Angiogenesis Inhibitors; Animals; Circadian Rhythm; Disease Models, Animal; Disease Progression; Echocardiography; Heart Ventricles; Hemodynamics; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Lung; Male; Pulmonary Artery; Pyrroles; Rats; Rats, Sprague-Dawley; Systole; Telemetry; Tunica Intima; Vascular Remodeling

Pulmonary hypertension (PH) is a progressive disease arising from remodeling and narrowing of pulmonary arteries (PAs) resulting in high pulmonary blood pressure and ultimately right ventricular failure. Elevated production of reactive oxygen species by NADPH oxidase 4 (Nox4) is associated with increased pressure in PH. However, the cellular location of Nox4 and its contribution to aberrant vascular remodeling in PH remains poorly understood. Therefore, we sought to identify the vascular cells expressing Nox4 in PAs and determine the functional relevance of Nox4 in PH.. Elevated expression of Nox4 was detected in hypertensive PAs from 3 rat PH models and human PH using qualititative real-time reverse transcription polymerase chain reaction, Western blot, and immunofluorescence. In the vascular wall, Nox4 was detected in both endothelium and adventitia, and perivascular staining was prominently increased in hypertensive lung sections, colocalizing with cells expressing fibroblast and monocyte markers and matching the adventitial location of reactive oxygen species production. Small-molecule inhibitors of Nox4 reduced adventitial reactive oxygen species generation and vascular remodeling as well as ameliorating right ventricular hypertrophy and noninvasive indices of PA stiffness in monocrotaline-treated rats as determined by morphometric analysis and high-resolution digital ultrasound. Nox4 inhibitors improved PH in both prevention and reversal protocols and reduced the expression of fibroblast markers in isolated PAs. In fibroblasts, Nox4 overexpression stimulated migration and proliferation and was necessary for matrix gene expression.. These findings indicate that Nox4 is prominently expressed in the adventitia and contributes to altered fibroblast behavior, hypertensive vascular remodeling, and development of PH.

Topics: Adventitia; Animals; Antihypertensive Agents; Cell Movement; Cell Proliferation; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Extracellular Matrix; Familial Primary Pulmonary Hypertension; Fibroblasts; HEK293 Cells; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Male; Mice; Mice, Inbred C57BL; Monocrotaline; NADPH Oxidase 4; NADPH Oxidases; Pulmonary Artery; Pyrroles; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Signal Transduction; Time Factors; Transfection; Up-Regulation

The efficacy of endothelin (ET) receptor antagonist bosentan in patients with severe pulmonary arterial hypertension (PAH) remains limited, partly because its higher doses for potential blockade of ET receptors have never been tested due to liver dysfunction. We hypothesized that rigorous blockade of ET receptors using the novel dual ET receptor antagonist macitentan would be effective in treating severe PAH without major side effects in a preclinical model appropriately representing the human disorder. In normal rats, 30 mg·kg·d of macitentan completely abolished big ET-1-induced increases in right ventricle (RV) systolic pressure. Adult male rats were injected with SU5416, a vascular endothelial growth factor blocker, and exposed to hypoxia for 3 weeks and then to normoxia for an additional 5 weeks (total 8 weeks). In intrapulmonary arterial rings isolated from rats with severe PAH, macitentan concentration dependently inhibited ET-1-induced contraction. Long-term treatment with macitentan (30 mg·kg·d, from week 3 to 8) reversed the high RV systolic pressure with preserved cardiac output. Development of RV hypertrophy, luminal occlusive lesions and medial wall thickening were also significantly improved without increasing serum levels of liver enzymes by macitentan. In conclusion, efficacious blockade of ET receptors with macitentan would reverse severe PAH without major adverse effects.

Topics: Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Indoles; Male; Pyrimidines; Pyrroles; Rats; Rats, Sprague-Dawley; Severity of Illness Index; Sulfonamides; Time Factors; Vascular Endothelial Growth Factor A

Pulmonary arterial hypertension (PAH) is a vasculopathy characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation and suppressed apoptosis. This results in both increase in pulmonary arterial pressure and pulmonary vascular resistance. Recent studies have shown the implication of the signal transducer and activator of transcription 3 (STAT3)/bone morphogenetic protein receptor 2 (BMPR2)/peroxisome proliferator-activated receptor gamma (PPARγ) in PAH. STAT3 activation induces BMPR2 downregulation, decreasing PPARγ, which both contribute to the proproliferative and antiapoptotic phenotype seen in PAH. In chondrocytes, activation of this axis has been attributed to the advanced glycation end-products receptor (RAGE). As RAGE is one of the most upregulated proteins in PAH patients' lungs and a strong STAT3 activator, we hypothesized that by activating STAT3, RAGE induces BMPR2 and PPARγ downregulation, promoting PAH-PASMC proliferation and resistance to apoptosis.. In vitro, using PASMCs isolated from PAH and healthy patients, we demonstrated that RAGE is overexpressed in PAH-PASMC (6-fold increase), thus inducing STAT3 activation (from 10% to 40% positive cells) and decrease in BMPR2 and PPARγ levels (>50% decrease). Pharmacological activation of RAGE in control cells by S100A4 recapitulates the PAH phenotype (increasing RAGE by 6-fold, thus activating STAT3 and decreasing BMPR2 and PPARγ). In both conditions, this phenotype is totally reversed on RAGE inhibition. In vivo, RAGE inhibition in monocrotaline- and Sugen-induced PAH demonstrates therapeutic effects characterized by PA pressure and right ventricular hypertrophy decrease (control rats have an mPAP around 15 mm Hg, PAH rats have an mPAP >40 mm Hg, and with RAGE inhibition, mPAP decreases to 20 and 28 mm Hg, respectively, in MCT and Sugen models). This was associated with significant improvement in lung perfusion and vascular remodeling due to decrease in proliferation (>50% decrease) and BMPR2/PPARγ axis restoration (increased by ≥60%).. We have demonstrated the implications of RAGE in PAH etiology. Thus, RAGE constitutes a new attractive therapeutic target for PAH.

Topics: Adult; Aged; Animals; Apoptosis; Arterial Pressure; Bone Morphogenetic Protein Receptors, Type II; Case-Control Studies; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Familial Primary Pulmonary Hypertension; Female; Glycation End Products, Advanced; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Male; Middle Aged; Monocrotaline; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; PPAR gamma; Pulmonary Artery; Pyrroles; Rats; Rats, Sprague-Dawley; Receptor for Advanced Glycation End Products; Receptors, Immunologic; RNA Interference; S100 Proteins; Signal Transduction; STAT3 Transcription Factor; Transfection; Up-Regulation

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signal-transduction pathway is impaired in many cardiovascular diseases, including pulmonary arterial hypertension (PAH). Riociguat (BAY 63-2521) is a stimulator of sGC that works both in synergy with and independently of NO to increase levels of cGMP. The aims of this study were to investigate the role of NO-sGC-cGMP signaling in a model of severe PAH and to evaluate the effects of sGC stimulation by riociguat and PDE5 inhibition by sildenafil on pulmonary hemodynamics and vascular remodeling in severe experimental PAH.. Severe angioproliferative PAH was induced in rats by combined exposure to the vascular endothelial growth factor receptor antagonist SU5416 and hypoxia (SUHx). Twenty-one days thereafter rats were randomized to receive either riociguat (10 mg/kg/day), sildenafil (50 mg/kg/day) or vehicle by oral gavage, for 14 days until the day of the terminal hemodynamic measurements. Administration of riociguat or sildenafil significantly decreased right ventricular systolic pressure (RVSP). Riociguat significantly decreased RV hypertrophy (RVH) (0.55 ± 0.02, p<0.05), increased cardiac output (60.8 ± .8 mL/minute, p<0.05) and decreased total pulmonary resistance (4.03 ± 0.3 mmHg min(-1) ml(-1) 100 g BW, p<0.05), compared with sildenafil and vehicle. Both compounds significantly decreased the RV collagen content and improved RV function, but the effects of riociguat on tricuspid annular plane systolic excursion and RV myocardial performance were significantly better than those of sildenafil (p<0.05). The proportion of occluded arteries was significantly lower in animals receiving riociguat than in those receiving vehicle (p<0.05); furthermore, the neointima/media ratio was significantly lower in those receiving riociguat than in those receiving sildenafil or vehicle (p<0.05).. Riociguat and sildenafil significantly reduced RVSP and RVH, and improved RV function compared with vehicle. Riociguat had a greater effect on hemodynamics and RVH than sildenafil.

Topics: Animals; Apoptosis; Blood Pressure; Blotting, Western; Caspase 3; Cell Proliferation; Cyclic GMP; Guanylate Cyclase; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Immunohistochemistry; Indoles; Lung; Male; Nitric Oxide Synthase Type III; Phosphodiesterase 5 Inhibitors; Piperazines; Purines; Pyrazoles; Pyrimidines; Pyrroles; Random Allocation; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; Sildenafil Citrate; Soluble Guanylyl Cyclase; Sulfones; Time Factors; Treatment Outcome

C-type natriuretic peptide (CNP) is a local regulator of vascular tone and remodeling in many vascular beds. However, the role of CNP in modulating pulmonary arterial hypertensive and vascular remodeling responses is unclear. The purpose of this study was to determine if CNP is capable of preventing the development of pulmonary hypertension (PH).. We used animal models of PH caused by chronic hypoxia alone or in combination with the vascular endothelial growth factor (VEGF) receptor blocker SU5416. We measured pulmonary hemodynamics, right ventricular hypertrophy and vascular remodeling effects in response to a continuous infusion of low dose or high dose CNP or vehicle placebo.. Right ventricular hypertrophy and a marked elevation in right ventricular systolic pressure (RVSP) were seen in both models of PH. Rats treated with the combination of SU5416 and chronic hypoxia also developed pulmonary endothelial hyperproliferative lesions. Continuous intravenous infusion of CNP at either dose did not attenuate the development of PH, right ventricular hypertrophy or vascular remodeling in either of the models of PH despite a three-fold increase in serum CNP levels.. CNP does not prevent the development of PH in the chronic hypoxia or SU5416 plus hypoxia models of pulmonary hypertension suggesting that CNP may not play an important modulatory role in human PH.

Topics: Animals; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Lung; Male; Natriuretic Agents; Natriuretic Peptide, C-Type; Protein Kinase Inhibitors; Pyrroles; Rats; Rats, Sprague-Dawley; Receptors, Vascular Endothelial Growth Factor

Administration of the VEGF receptor blocker SU5416 to rats causes alveolar septal cell apoptosis and emphysema; both can be prevented by a superoxide dismutase mimetic. Here we show that SU5416 induces the expression of heme oxygenase-1 in the lung tissue and that administration of antioxidant N-acetyl-l-cysteine protects alveolar septal cells against apoptosis, as demonstrated by caspase-3 lung immunohistochemistry, and against emphysema.

Topics: Acetylcysteine; Animals; Apoptosis; Disease Models, Animal; Dose-Response Relationship, Drug; Emphysema; Heme Oxygenase-1; Hypertrophy, Right Ventricular; Indoles; Lung; Male; Oxidative Stress; Pyrroles; Rats; Rats, Sprague-Dawley; Receptors, Vascular Endothelial Growth Factor

To determine whether disruption of vascular endothelial growth factor (VEGF)-VEGF receptor (VEGFR) signaling in the newborn has long-term effects on lung structure and function, we injected 1-day-old newborn rat pups with a single dose of Su-5416, a VEGFR inhibitor, or vehicle (controls). Lungs from infant (3-wk-old) and adult (3- to 4-mo-old) rats treated with Su-5416 as newborns showed reductions in arterial density (82 and 31%, respectively) and alveolar counts (45 and 29%) compared with controls. Neonatal treatment with Su-5416 increased right ventricle weight to body wt ratios (4.2-fold and 2.0-fold) and pulmonary arterial wall thickness measurements (2.7-fold and 1.6-fold) in infant and adult rats, respectively, indicating marked pulmonary hypertension. We conclude that treatment of newborn rats with the VEGFR inhibitor Su-5416 impaired pulmonary vascular growth and postnatal alveolarization and caused pulmonary hypertension and that these effects were long term, persisting well into adulthood.

Topics: Angiography; Animals; Animals, Newborn; Birth Weight; Chronic Disease; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Lung; Pulmonary Alveoli; Pulmonary Artery; Pulmonary Circulation; Pyrroles; Rats; Rats, Sprague-Dawley; Receptor Protein-Tyrosine Kinases; Receptors, Growth Factor; Receptors, Vascular Endothelial Growth Factor; Stress, Physiological