Cannabidiol may prevent the development of congestive hepatopathy secondary to right ventricular hypertrophy associated with pulmonary hypertension in rats.

BACKGROUND: Pulmonary hypertension (PH) can cause right ventricular (RV) failure and subsequent cardiohepatic syndrome referred to as congestive hepatopathy (CH). Passive blood stasis in the liver can affect inflammation, fibrosis, and ultimately cirrhosis. Cannabidiol (CBD) has many beneficial properties including anti-inflammatory and reduces RV systolic pressure and RV hypertrophy in monocrotaline (MCT)-induced PH in rats. Thus, it suggests that CBD may have the potential to limit CH development secondary to RV failure. The present study aimed to determine whether chronic administration of CBD can inhibit the CH secondary to RV hypertrophy associated with MCT-induced PH. METHODS: The experiments involved rats with and without MCT-induced PH. CBD (10 mg/kg) or its vehicle was administered once daily for 3 weeks after MCT injection (60 mg/kg). RESULTS: Monocrotaline administration increased the liver/body weight ratio. In histology examinations, we observed necrosis and vacuolar degeneration of hepatocytes as well as sinusoidal congestion. In biochemical studies, we observed increased levels of nuclear factor-κappa B (NF-κB), tumour necrosis factor-alpha (TNA-α), interleukin 1 beta (IL-1ß), and interleukin 6 (IL-6). CBD administration to PH rats reduced the liver/body weight ratio, improved the architecture of the liver, and inhibited the formation of necrosis. Cannabidiol also decreased the level of NF-κB, TNF-α, IL-1ß and IL-6. CONCLUSIONS: The studies show that CBD can protect the liver from CH probably through attenuating PH, protective effects on the RV, and possibly direct anti-inflammatory effects on liver tissue through regulation of the NF-κB pathway.

Copaiba oil improves pulmonary nitric oxide bioavailability in monocrotaline-treated rats.

Oxidative stress is involved in increased pulmonary vascular resistance (PVR) and right ventricular (RV) hypertrophy, characteristics of pulmonary arterial hypertension (PAH). Copaiba oil, an antioxidant compound, could attenuate PAH damage. This study's aim was to determine the effects of copaiba oil on lung oxidative stress, PVR, and mean pulmonary arterial pressure (mPAP) in the monocrotaline (MCT) model of PAH. Male Wistar rats (170 g, n = 7/group) were divided into four groups: control, MCT, copaiba oil, and MCT + copaiba oil (MCT-O). PAH was induced by MCT (60 mg/kg i.p.) and, after 1 week, the treatment with copaiba oil (400 mg/kg/day gavage) was started for 14 days. Echocardiographic and hemodynamic measurements were performed. RV was collected for morphometric evaluations and lungs and the pulmonary artery were used for biochemical analysis. Copaiba oil significantly reduced RV hypertrophy, PVR, mPAP, and antioxidant enzyme activities in the MCT-O group. Moreover, increased nitric oxide synthase and decreased NADPH oxidase activities were observed in the MCT-O group. In conclusion, copaiba oil was able to improve the balance between nitric oxide and reactive oxygen species in lungs and the pulmonary artery and to reduce PVR, which could explain a decrease in RV hypertrophy in this PAH model.

Kallikrein-related peptidase-8 (KLK8) aggravated hypoxia-induced right ventricular hypertrophy by targeting P38 MAPK/P53 signaling pathway.

Right ventricular (RV) hypertrophy and further heart failure are major co-morbidities, resulting in the premature death of patients with hypoxic pulmonary hypertension (HPH). The regulatory effects of kallikrein-related peptidase (KLK) family members on cardiac function have been extensively studied. However, to the best of the authors' knowledge, the regulatory effects of KLK8 on RV hypertrophy caused by HPH have yet to be reported. The aim of the present study was to assess KLK8 expression in the RV tissue of HPH-modeled rats, and to further explore the effects and underlying mechanism of KLK8 in regulating the hypertrophy of hypoxia-induced H9c2 cardiomyocytes. In HPH model rats, increases in the right ventricle hypertrophy index, the right ventricular systolic pressure, cardiac output, as well as pulmonary artery wall thickness were observed. Western blot analysis revealed that KLK8 expression and MAPK/p53 signaling activity were enhanced in the RVs of rats in an RV HPH rat model. In hypoxia-induced H9c2 cardiomyocytes, KLK8 overexpression promoted cardiomyocyte hypertrophy, whereas KLK8 silencing showed the opposite results. KLK8 overexpression increased the expression levels of ventricular hypertrophy markers, including atrial natriuretic peptide, brain natriuretic peptide and myosin heavy chain 7, which were blocked upon addition of the p38 MAPK inhibitor, SB202190. Conversely, KLK8 silencing caused a decrease in the expression levels of the ventricular hypertrophy markers, which were further reduced via inhibition of the p38 MAPK/p53 signaling pathway. Taken together, the results of the present study have shown that KLK8 may subtly regulate RV hypertrophy, and therefore KLK8 may be a promising therapeutic target for treating HPH-induced RV hypertrophy.

TPN171H alleviates pulmonary hypertension via inhibiting inflammation in hypoxia and monocrotaline-induced rats.

Pulmonary hypertension (PH) is a progressive and life-threatening disease with poor prognosis despite many advances in medical therapy over the past 20 years. Novel therapies which target on the underlying pathology of PH are still urgent to be met. TPN171H is a recently found new compound that exhibits potent pharmacological effects in PH via inhibiting phosphodiesterase type 5 (PDE-5). However, as one icariin derivative, the anti-inflammatory effects of TPN171H for treating PH are not clear. The present study was designed to investigate the therapeutical effect of TPN171H against inflammation in PH and reveal the underlying mechanism. Hypoxia and monocrotaline (MCT)-induced PH rat models were established, which were treated by oral administration of TPN171H (5, 25 mg/kg/d) or sildenafil (25 mg/kg/d). The right ventricle systolic pressure (RVSP), right ventricle hypertrophy index (RVHI) and vascular remodeling were measured. The results suggested that TPN171H significantly reduced RVSP and RVHI, and reversed pulmonary vascular remodeling in rats with both models. Furthermore, in in vivo and in vitro research, our data suggested that TPN171H remarkably suppressed cathepsin B-mediated NLRP3 inflammasome activation, which may contribute to its therapeutical function for PH.

Inflammatory Glycoprotein 130 Signaling Links Changes in Microtubules and Junctophilin-2 to Altered Mitochondrial Metabolism and Right Ventricular Contractility.

BACKGROUND: Right ventricular dysfunction (RVD) is the leading cause of death in pulmonary arterial hypertension (PAH), but no RV-specific therapy exists. We showed microtubule-mediated junctophilin-2 dysregulation (MT-JPH2 pathway) causes t-tubule disruption and RVD in rodent PAH, but the druggable regulators of this critical pathway are unknown. GP130 (glycoprotein 130) activation induces cardiomyocyte microtubule remodeling in vitro; however, the effects of GP130 signaling on the MT-JPH2 pathway and RVD resulting from PAH are undefined. METHODS: Immunoblots quantified protein abundance, quantitative proteomics defined RV microtubule-interacting proteins (MT-interactome), metabolomics evaluated the RV metabolic signature, and transmission electron microscopy assessed RV cardiomyocyte mitochondrial morphology in control, monocrotaline, and monocrotaline-SC-144 (GP130 antagonist) rats. Echocardiography and pressure-volume loops defined the effects of SC-144 on RV-pulmonary artery coupling in monocrotaline rats (8-16 rats per group). In 73 patients with PAH, the relationship between interleukin-6, a GP130 ligand, and RVD was evaluated. RESULTS: SC-144 decreased GP130 activation, which normalized MT-JPH2 protein expression and t-tubule structure in the monocrotaline RV. Proteomics analysis revealed SC-144 restored RV MT-interactome regulation. Ingenuity pathway analysis of dysregulated MT-interacting proteins identified a link between microtubules and mitochondrial function. Specifically, SC-144 prevented dysregulation of electron transport chain, Krebs cycle, and the fatty acid oxidation pathway proteins. Metabolomics profiling suggested SC-144 reduced glycolytic dependence, glutaminolysis induction, and enhanced fatty acid metabolism. Transmission electron microscopy and immunoblots indicated increased mitochondrial fission in the monocrotaline RV, which SC-144 mitigated. GP130 antagonism reduced RV hypertrophy and fibrosis and augmented RV-pulmonary artery coupling without altering PAH severity. In patients with PAH, higher interleukin-6 levels were associated with more severe RVD (RV fractional area change 23±12% versus 30±10%, P=0.002). CONCLUSIONS: GP130 antagonism reduces MT-JPH2 dysregulation, corrects metabolic derangements in the RV, and improves RVD in monocrotaline rats.

Right ventricular myocardial oxygen tension is reduced in monocrotaline-induced pulmonary hypertension in the rat and restored by myo-inositol trispyrophosphate.

Pulmonary hypertension (PH) initially results in compensatory right ventricular (RV) hypertrophy, but eventually in RV failure. This transition is poorly understood, but may be triggered by hypoxia. Measurements of RV oxygen tension (pO2) in PH are lacking. We hypothesized that RV hypoxia occurs in monocrotaline-induced PH in rats and that myo-inositol trispyrophosphate (ITPP), facilitating oxygen dissociation from hemoglobin, can relieve it. Rats received monocrotaline (PH) or saline (control) and 24 days later echocardiograms, pressure-volume loops were obtained and myocardial pO2 was measured using a fluorescent probe. In PH mean pulmonary artery pressure more than doubled (35 ± 5 vs. 15 ± 2 in control), RV was hypertrophied, though its contractility was augmented. RV and LV pO2 was 32 ± 5 and 15 ± 8 mmHg, respectively, in control rats. In PH RV pO2 was reduced to 18 ± 9 mmHg, while LV pO2 was unchanged. RV pO2 correlated with RV diastolic wall stress (negatively) and LV systolic pressure (positively). Acute ITPP administration did not affect RV or LV pO2 in control animals, but increased RV pO2 to 26 ± 5 mmHg without affecting LV pO2 in PH. RV oxygen balance is impaired in PH and as such can be an important target for PH therapy. ITPP may be one of such potential therapies.

Quercetin, Perillyl Alcohol, and Berberine Ameliorate Right Ventricular Disorders in Experimental Pulmonary Arterial Hypertension: Effects on miR-204, miR-27a, Fibrotic, Apoptotic, and Inflammatory Factors.

ABSTRACT: Pulmonary arterial hypertension (PAH) is a pulmonary vascular disease causing right ventricular (RV) hypertrophy, failure, and death. Some miRNAs are involved in the pathophysiology of PAH. As the current treatments cannot prevent the progression of the disease, we investigated whether 3 plant derivatives, namely perillyl alcohol (PA), quercetin (QS), and berberine (BBR), can improve RV function and affect the expression of miR-204, miR-27a, and biochemical factors in monocrotaline-induced PAH (MCT-PAH). Thirty-six rats were divided into control (CTL), MCT, MCT+Veh (vehicle), MCT+PA, MCT+QS, and MCT + BBR groups (n = 6 each). After inducing PAH using MCT (60 mg/kg), PA (50 mg/kg), QS (30 mg/kg), and BBR (30 mg/kg) were administrated daily for 3 weeks. miR-204 expression, total antioxidant capacity, and antiapoptotic protein Bcl-2 significantly declined in the RV of PAH rats, and PA, QS, and BBR treatment significantly compensated for these decreases. Proapoptotic protein Bax and p21 cell cycle inhibitor increased in the RV. All 3 herbal derivatives compensated for Bax increase, and BBR caused a decrease in p21. TNFα, IL-6, and malondialdehyde increased in the RV, and PA, QS, and BBR significantly counterbalanced these increases. miR-27a expression was not affected by MCT and plant derivatives. Overall, PA, QS, and BBR improved ventricular disorders in rats with PAH by decreasing inflammation, apoptosis, and fibrosis and increasing the antioxidant-to-oxidant ratio. Therefore, these herbal derivatives may be considered as target therapeutic goals for this disease either alone or in combination with current medications.

S-Nitroso-L-Cysteine Ameliorated Pulmonary Hypertension in the MCT-Induced Rats through Anti-ROS and Anti-Inflammatory Pathways.

Pulmonary hypertension (PH) is a progressive and life-threatening chronic disease in which increased pulmonary artery pressure (PAP) and pulmonary vasculature remodeling are prevalent. Inhaled nitric oxide (NO) has been used in newborns to decrease PAP in the clinic; however, the effects of NO endogenous derivatives, S-nitrosothiols (SNO), on PH are still unknown. We have reported that S-nitroso-L-cysteine (CSNO), one of the endogenous derivatives of NO, inhibited RhoA activity through oxidative nitrosation of its C16/20 residues, which may be beneficial for both vasodilation and remodeling. In this study, we presented data to show that inhaled CSNO attenuated PAP in the monocrotaline- (MCT-) induced PH rats and, moreover, improved right ventricular (RV) hypertrophy and fibrosis induced by RV overloaded pressure. In addition, aerosolized CSNO significantly inhibited the hyperactivation of signal transducers and activators of transduction 3 (STAT3) and extracellular regulated protein kinases (ERK) pathways in the lung of MCT-induced rats. CSNO also regulated the expression of smooth muscle contractile protein and improved aberrant endoplasmic reticulum (ER) stress and mitophagy in lung tissues following MCT induction. On the other hand, CSNO inhibited reactive oxygen species (ROS) production in vitro, which is induced by angiotensin II (AngII) as well as interleukin 6 (IL-6). In addition, CSNO inhibited excessive ER stress and mitophagy induced by AngII and IL-6 in vitro; finally, STAT3 and ERK phosphorylation was inhibited by CSNO in a concentration-dependent manner. Taken together, CSNO led to pulmonary artery relaxation and regulated pulmonary circulation remodeling through anti-ROS and anti-inflammatory pathways and may be used as a therapeutic option for PH treatment.

Metabolic remodeling in the right ventricle of rats with severe pulmonary arterial hypertension.

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 branched­chain 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 long­chain acylcarnitines, which transport FA from the cytosol to the mitochondria and are essential for beta­oxidation. 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.

Evaluation of right coronary vascular dysfunction in severe pulmonary hypertensive rats using synchrotron radiation microangiography.

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 18F-FDG Positron emission tomography (PET) and magnetic resonance imaging (MRI). Endothelium-dependent and endothelium-independent vasodilator responses were significantly attenuated in the medium and small arteries of severe PH rats. ERA treatment significantly improved RCA vascular function compared with the untreated group. ERA treatment improved both the decrease in ejection fraction and the increased glucose uptake, and reduced RV remodeling. In addition, the upregulation of inflammatory genes in the RV was almost suppressed by ERA treatment. We found impairment of vasodilator responses in the RCA of severe PH rat models. Endothelin-1 activation in the RCA plays a major role in impaired vascular function in PH rats and is partially restored by ERA treatment. Treatment of PH with ERA may improve RV function in part by indirectly attenuating right heart afterload and in part by associated improvements in right coronary endothelial function.NEW & NOTEWORTHY We demonstrated for the first time the impairment of vascular responses in the right coronary artery (RCA) of the dysfunctional right heart in pulmonary hypertensive rats in vivo. Treatment with an endothelin-1 receptor antagonist ameliorated vascular dysfunction in the RCA, enabled tissue remodeling of the right heart, and improved cardiac function. Our results suggest that impaired RCA function might also contribute to the early progression to heart failure in patients with severe pulmonary arterial hypertension (PAH). The endothelium of the coronary vasculature might be considered as a potential target in treatments to prevent heart failure in severe patients with PAH.

Perillyl alcohol suppresses monocrotaline-induced pulmonary arterial hypertension in rats via anti-remodeling, anti-oxidant, and anti-inflammatory effects.

Background: Pulmonary arterial hypertension (PAH) is a disastrous disease that current treatments cannot prevent its progression. The present study investigated the effects of perillyl alcohol (PA), a natural monoterpene, on the experimental PAH in male Wistar rats. Methods: Rats divided into eight groups of control, Monocrotaline (MCT), MCT+vehicle, and MCT+PA with doses of 20, 30, 40, 50, and 60 mg/kg. PAH was induced by a single injection of monocrotaline (60 mg/kg) on day 0. The animals in the groups of MCT+vehicle and MCT+PA received the vehicle or PA from day 22 to 42 once a day. On day 43, under general anesthesia, right ventricular systolic pressure (RVSP), as an index of pulmonary artery systolic pressure, and the ratio of the right ventricle to the left ventricle plus septum weight, as the right ventricular hypertrophy index (RVHI), were measured. Also, some histological and biochemical indices were assessed in the lung tissue. Results: MCT significantly (p < .001) enhanced the RVSP and RVHI compared to the control group (89.4 ± 8.2 vs 23 ± 3.3 mmHg & 0.63 ± 0.08 vs 0.26 ± 0.04 respectively). It also increased oxidative stress and inflammatory cytokines and reduced Bax/Bcl2 ratio. Treatment with PA significantly recovered RVSP and hypertrophy index and suppressed vascular cell proliferation, oxidant production, and inflammatory processes. Conclusion: PA exerted noticeable protective and curative effects against MCT-induced PAH and pulmonary vascular remodeling through inhibiting cellular proliferation, oxidative stress, and inflammation. Therefore, PA can be considered as a new therapeutic goal for the treatment of PAH.

Maxingxiongting mixture attenuates hypoxia pulmonary arterial hypertension to improve right ventricular hypertrophy by inhibiting the rho-kinase signaling pathway.

OBJECTIVE: To explore the mechanism of Maxingxiongting mixture (MXXTM) on pulmonary hypertension in a rat model established by intraperitoneal injection of monocrotaline solution, smoking and forced swimming. METHODS: A total of 30 male Sprague-Dawley rats were randomly divided into five groups: control group, model group, high-dose of MXXTM group (HM), low-dose of MXXTM group (LM), and fasudil group. The mean pulmonary artery pressure (mPAP) was measured by using a miniature catheter. Lung tissue and right ventricular tissue sections were stained with hematoxylin-eosin. The right ventricle (RV) and left ventricle + septum (LV + S) were weighted. RV/(LV+S) was calculated to reflect the degree of right ventricular hypertrophy. Rho/Rho-kinase signaling pathway key proteins (RhoA, ROCK Ⅰ and ROCK Ⅱ) in rat right ventricular tissue were measured by Western blot analysis. The levels of serum hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and the levels of plasma renin activity (PRA), angiotensin Ⅱ (ANG-Ⅱ), aldosterone (ALD) in rat anticoagulated plasma were all measured by enzyme-linked immunosorbent assay. RESULTS: Compared with the control group, the mPAP and RV/(LV+S) in the model group were significantly increased. Administration of fasudil resulted in a significant decrease of mPAP and RV/ (LV+S). In the HM group and LM group, mPAP and RV/ (LV+S) were significantly lower than the model group. Compared with the control group, the contents of HIF-1α, VEGF, PRA, ANG-Ⅱ and ALD in the model group were significantly increased. The administration of fasudil and high-dose MXXTM significantly reduced the contents of HIF-1α, VEGF, PRA, ANG-II and ALD. Compared with the control group, the expression of RhoA, ROCK Ⅰ and ROCK Ⅱ in the right ventricle of the model group were significantly increased. The administration of fasudil and high-dose MXXTM significantly reduced the expression of RhoA and Rock Ⅱ proteins. Our results indicated that high-dose of MXXTM had similar effects on reducing pulmonary artery pressure and improving right ventricular remodeling to fasudil. However, MXXTM was unable to restore parameters above to control levels. CONCLUSIONS: MXXTM attenuates hypoxia pulmonary arterial hypertension to improve right ventricular hypertrophy by inhibiting the Rho-kinase signaling pathway.

Protective effect of nicotinamide and L-arginine against monocrotaline-induced pulmonary hypertension in rats: gender dependence.

BACKGROUND: The purpose of this paper was to examine the effects of nicotinamide (ND) and L-arginine (L-ARG) on pulmonary vascular and heart changes induced by pulmonary hypertension in rats in a gender-dependent way. METHODS: Experiments were performed on male (M) and female (F) rats. PAH was induced via monocrotaline injection (sc, 60/kg B.W.) on day one of the 23-day observational period. After that, the animals were sacrificed, hearts removed and weighed and the papillary muscles isolated to measure force of contraction (Fc). Morphological changes of pulmonary vessels were also examined. RESULTS: Mixed diet supplementation with L-ARG + ND prevented highly significant right ventricle enlargement induced by PAH in both, male and female rats. Weight ratios between the right ventricle (RV) on one side and the left ventricle with septum on the other (LV + S) decreased from 0.46 ± 0.016 g to 0.29 ± 0.006 g in males and from 0.63 ± 0.03 g to 0.24 ± 0.008 g in females, n = 6, p < 0.001. Additionally, PAH increased basal contractility in female groups, and each of the diet allocations (L-ARG, ND, and mixed) were found to restore contractility to control values. All diet protocols in male and female restored decreased responsiveness of the myocardium to norepinephrine in hearts obtained from rats with PAH and prevented vascular changes observed in pulmonary hypertension (thickness of blood vessels and cell infiltration). CONCLUSION: Our study suggests that L-arginine, nicotinamide or both play a positive role in right ventricle function or the process reducing pulmonary vascular remodeling especially in a gender-independent way.

Perillyle alcohol and Quercetin ameliorate monocrotaline-induced pulmonary artery hypertension in rats through PARP1-mediated miR-204 down-regulation and its downstream pathway.

BACKGROUND: Pulmonary artery hypertension (PAH) is a vascular disease in the lung characterized by elevated pulmonary arterial pressure (PAP). Many miRNAs play a role in the pathophysiology of PAH. Perillyle alcohol (PA) and Quercetin (QS) are plant derivatives with antioxidant and anti-proliferative properties. We investigated the effect of PA and QS on PAP, expression of PARP1, miR-204, and their targets, HIF1α and NFATc2, in experimental PAH. METHODS: Thirty rats were divided into control, MCT, MCT + Veh, MCT + PA and MCT + QS groups. MCT (60 mg/kg) was injected subcutaneously to induce PAH. PA (50 mg/kg daily) and QS (30 mg/kg daily) were administered for 3 weeks after inducing PAH. PAP, lung pathology, expression of miRNA and mRNA, and target proteins were evaluated through right ventricle cannulation, H&E staining, real-time qPCR, and western blotting, respectively. RESULTS: Inflammation and lung arteriole thickness in the MCT group increased compared to control group. PA and QS ameliorated inflammation and reduced arteriole thickness significantly. miR-204 expression decreased in PAH rats (p < 0.001). PA (p < 0.001) and QS (p < 0.01) significantly increased miR-204 expression. Expression of PARP1, HIF1α, NFATc2, and α-SMA mRNA increased significantly in MCT + veh rats (all p < 0.001), and these were reduced after treatment with PA and QS (both p < 0.01). PA and QS also decreased the expression of PARP1, HIF1α, and NFATc2 proteins that had increased in MCT + Veh group. CONCLUSION: PA and QS improved PAH possibly by affecting the expression of PARP1 and miR-204 and their downstream targets, HIF1a and NFATc2. PA and QS may be therapeutic goals in the treatment of PAH.

Preventive but nontherapeutic effect of danshensu on hypoxic pulmonary hypertension.

OBJECTIVES: Danshensu is a traditional Chinese medicine that is used for treatment of cardiovascular diseases. We previously demonstrated its preventive effect against early-stage hypoxic pulmonary hypertension (HPH) in a rat model. To determine whether danshensu treatment might be useful for patients with chronic HPH, we examined its therapeutic effect in rats with prolonged HPH. METHODS: Adult Sprague-Dawley rats received danshensu (80, 160, and 320 mg/kg) during or after hypoxia exposure to assess preventive and therapeutic effects, respectively. Right ventricle systolic pressure (RVSP), right ventricle hypertrophy index (RVHI), and mean left carotid artery pressure (mCAP) were measured in each group. Western blotting was used to assess transforming growth factor (TGF)-ß expression levels in rats and cultured cells exposed to hypoxia. RESULTS: Preventive danshensu treatment significantly reduced the elevation of RVSP and RVHI in rats exposed to hypoxia, whereas therapeutic danshensu treatment did not; mCAP did not change in any treatment group. The increased expression levels of TGF-ß induced by hypoxia were inhibited by preventive danshensu treatment, but not by therapeutic danshensu treatment. CONCLUSIONS: Although danshensu treatment could prevent HPH, it had no obvious therapeutic effect after development of HPH. Therefore, danshensu might be suitable for clinical treatment of early-stage HPH.

NTP42, a novel antagonist of the thromboxane receptor, attenuates experimentally induced pulmonary arterial hypertension.

BACKGROUND: NTP42 is a novel antagonist of the thromboxane prostanoid receptor (TP), currently in development for the treatment of pulmonary arterial hypertension (PAH). PAH is a devastating disease with multiple pathophysiological hallmarks including excessive pulmonary vasoconstriction, vascular remodelling, inflammation, fibrosis, in situ thrombosis and right ventricular hypertrophy. Signalling through the TP, thromboxane (TX) A2 is a potent vasoconstrictor and mediator of platelet aggregation. It is also a pro-mitogenic, pro-inflammatory and pro-fibrotic agent. Moreover, the TP also mediates the adverse actions of the isoprostane 8-iso-prostaglandin F2α, a free-radical-derived product of arachidonic acid produced in abundance during oxidative injury. Mechanistically, TP antagonists should treat most of the hallmarks of PAH, including inhibiting the excessive vasoconstriction and pulmonary artery remodelling, in situ thrombosis, inflammation and fibrosis. This study aimed to investigate the efficacy of NTP42 in the monocrotaline (MCT)-induced PAH rat model, alongside current standard-of-care drugs. METHODS: PAH was induced by subcutaneous injection of 60 mg/kg MCT in male Wistar-Kyoto rats. Animals were assigned into groups: 1. 'No MCT'; 2. 'MCT Only'; 3. MCT + NTP42 (0.25 mg/kg BID); 4. MCT + Sildenafil (50 mg/kg BID), and 5. MCT + Selexipag (1 mg/kg BID), where 28-day drug treatment was initiated within 24 h post-MCT. RESULTS: From haemodynamic assessments, NTP42 reduced the MCT-induced PAH, including mean pulmonary arterial pressure (mPAP) and right systolic ventricular pressure (RSVP), being at least comparable to the standard-of-care drugs Sildenafil or Selexipag in bringing about these effects. Moreover, NTP42 was superior to Sildenafil and Selexipag in significantly reducing pulmonary vascular remodelling, inflammatory mast cell infiltration and fibrosis in MCT-treated animals. CONCLUSIONS: These findings suggest that NTP42 and antagonism of the TP signalling pathway have a relevant role in alleviating the pathophysiology of PAH, representing a novel therapeutic target with marked benefits over existing standard-of-care therapies.

Alginate Oligosaccharide Alleviates Monocrotaline-Induced Pulmonary Hypertension via Anti-Oxidant and Anti-Inflammation Pathways in Rats.

Pulmonary arterial hypertension (PAH) is a serious and fatal cardiovascular disorder characterized by increased pulmonary vascular resistance and progressive pulmonary vascular remodeling. The underlying pathological mechanisms of PAH are multi-factorial and multi-cellular. Alginate oligosaccharide (AOS), which is produced by depolymerizing alginate, shows better pharmacological activities and beneficial effects. The present study was undertaken to investigate the effects and potential mechanisms of AOS-mediated alleviation of pulmonary hypertension. Pulmonary hypertension was induced in Sprague-Dawley rats by a single intraperitoneal injection of monocrotaline (MCT; 60 mg/kg). Five weeks after the injection of MCT, AOS (5, 10, and 20 mg·kg-1·d-1) was injected intraperitoneally for another three weeks. The results showed that AOS prevented the development of MCT-induced pulmonary hypertension and right ventricular hypertrophy in a dose-dependent manner. AOS treatment also prevented MCT-induced pulmonary vascular remodeling via inhibition of the TGF-ß1/p-Smad2 signaling pathway. Furthermore, AOS treatment downregulated the expression of malondialdehyde, nicotinamide adenine dinucleotide phosphate oxidase, and pro-inflammatory cytokines, decreased macrophage infiltration, and upregulated the expression of anti-inflammatory cytokines. These findings indicate that AOS exerts anti-oxidative and anti-inflammatory effects in pulmonary arteries, which may contribute to the alleviation of pulmonary hypertension and pulmonary vascular remodeling.

Tsantan Sumtang attenuated chronic hypoxia-induced right ventricular structure remodeling and fibrosis by equilibrating local ACE-AngII-AT1R/ACE2-Ang1-7-Mas axis in rat.

ETHNOPHARMACOLOGICAL RELEVANCE: Tsantan Sumtang, which consists of Choerospondias axillaris (Roxb.) Burtt et Hill, Myristica fragrans Houtt and Santalum album L, is a traditional and common prescription of Tibetan medicine. Tsantan Sumtang originates from Four Tantra with properties of nourishing heart and has been used as a folk medicine for cardiovascular diseases and heart failure in Qinghai, Tibet and Inner Mongolia. Our previous studies found that Tsantan Sumtang showed beneficial effects on right ventricular structure in hypoxia rats, while the underling mechanism remains unclear. AIM OF THE STUDY: To elucidate the underlying mechanisms of Tsantan Sumtang attenuated right ventricular (RV) remodeling and fibrosis of chronic hypoxia-induced pulmonary arterial hypertension (HPAH) rats. MATERIALS AND METHODS: Fifty male Sprague Dawley (SD) rats (170 ± 20 g) were randomly divided into control group, hypoxia group, and hypoxia + Tsantan Sumtang groups (1.0 g·â€¯kg-1·day-1, 1.25 g·â€¯kg-1·day-1, 1.5 g ·kg-1·day-1). Rats in the hypoxia group and hypoxia + Tsantan Sumtang groups were maintained in a hypobaric chamber by adjusting the inner pressure and oxygen content to simulate an altitude of 4500 m for 28 days. The mean pulmonary arterial pressure (mPAP), right ventricle hypertrophy index (RVHI), the ratio of RV weight to tibia length (TL) (RV/TL), heart rate (HR) and RV systolic pressure (RVSP) was determined. Histomorphological assay of RV structure was evaluated by hematoxylin and eosin (HE) staining. RV tissue fibrosis was assessed by collagen proportion area (CPA), collagen I, collagen III and hydroxyproline content. CPA was obtained by picro-sirius red staining (PSR). The expression of collagen I and collagen III were detected by immunohistochemistry and western blotting. The hydroxyproline content was detected by alkaline hydrolysis. In addition, the level of angiotensin II (AngII) and angiotensin 1-7 (Ang1-7) in RV tissue was tested by enzyme-linked immune sorbent assay (ELISA). Protein expression of angiotensin-converting enzyme (ACE), AngII, AngII type 1 receptor (AT1R), angiotensin-converting enzyme 2 (ACE2), Mas receptor (Mas) were determined by immunohistochemistry and western blotting. mRNA level of ACE, AT1R, ACE2, Mas were tested by qPCR. The chemical profile of Tsantan Sumtang was revealed by UHPLC-Q-Exactive hybrid quadrupole-orbitrap mass analysis. RESULTS: Our results showed that RVHI, RV/TL and RVSP were significantly increased in HPAH rat. Furthermore, levels of collagen I, collagen III and hydroxyproline were up-regulated in RV tissue under hypoxia. We found that RV hypertrophy and fibrosis were associated with increased expression of ACE, AngII, AT1R as well as decreased expression of ACE2, Ang1-7 and Mas. RV remodeling and fibrosis were attenuated after Tsantan Sumtang administration by up-regulating ACE2 and Mas level as well as down-regulating ACE, AngII and AT1R levels in RV tissue. 35 constituents in Tsantan Sumtang were identified. CONCLUSION: Tsantan Sumtang attenuated RV remodeling and fibrosis in rat exposed to chronic hypoxia. The pharmacological effect of Tsantan Sumtang was based on equilibrating ACE-AngII-AT1R and ACE2-Ang1-7-Mas axis of RV tissue in HPAH rat.

Monocrotaline-induced pulmonary arterial hypertension: Time-course of injury and comparative evaluation of macitentan and Y-27632, a Rho kinase inhibitor.

Novel pharmacological approaches are needed to improve outcomes of patients with idiopathic pulmonary hypertension. Rho-associated protein kinase (ROCK) inhibitors have shown beneficial effects in preclinical models of pulmonary arterial hypertension (PAH), because of their role in the regulation of pulmonary artery vasoconstrictor tone and remodeling. We compared a ROCK inhibitor, Y-27632, for the first time with the dual endothelin receptor antagonist, macitentan, in a monocrotaline-induced rat pulmonary hypertension model. Different methods (echocardiography, hemodynamics, histology of right ventricle and pulmonary vessels, and circulating biomarkers) showed consistently that 100 mg/kg daily of Y-27632 and 10 mg/kg daily of macitentan slowed the progression of PAH both at the functional and structural levels. Treatments started on day 14 after monocrotaline injection and lasted 14 days. The findings of all experimental methods show that the selective ROCK inhibitor Y-27632 has more pronounced effects than macitentan, but a major limitation to its use is its marked peripheral vasodilating action.

Metabolic Response to Stress by the Immature Right Ventricle Exposed to Chronic Pressure Overload.

Background The right ventricle exposed to chronic pressure overload exhibits hypertrophy and decompensates when exposed to stress. We hypothesize that impaired ability to increase myocardial oxidative flux through pyruvate dehydrogenase leads to hypertrophied right ventricular (RV) dysfunction when exposed to hemodynamic stress, and pyruvate dehydrogenase stimulation can improve RV function. Methods and Results Infant male Yorkshire piglets (13.5±0.6 kg weight, n=19) were used to assess substrate fractional contribution to the citric acid cycle after sustained pulmonary artery banding (PAB). Carbon 13-labeled glucose, lactate, and leucine, oxidative substrate tracers for the citric acid cycle, were infused into the right coronary artery on 7 to 10 days after PAB. RV systolic pressure, RV free wall thickness, and individual cardiomyocyte cell size after PAB were significantly elevated compared with the sham group. Both fractional glucose and lactate oxidations in the PAB group were >2-fold higher than in the sham group. Pigs with overdrive atrial pacing (≈80% increase in heart rate) stress after PAB showed only a 22% increase in rate-pressure product from baseline before atrial pacing and limited carbohydrate oxidation rate in the right ventricle. Intracoronary infusion of dichloroacetate, a pyruvate dehydrogenase agonist, produced higher rate-pressure product (59% increase) in response to increased workload by atrial pacing in association with a marked increase in lactate oxidation. Conclusions The immature hypertrophied right ventricle shows limited ability to increase carbohydrate oxidation in response to tachycardia stress leading to energy supply/utilization imbalance and decreased systolic function. Enhanced pyruvate dehydrogenase activation by dichloroacetate increases energy supply and preserves hypertrophied RV contractile function during hemodynamic stress.