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.

Ferrostatin-1 Blunts Right Ventricular Hypertrophy and Dysfunction in Pulmonary Arterial Hypertension by Suppressing the HMOX1/GSH Signaling.

Ferroptosis plays a critical role in pulmonary arterial hypertension (PAH)-induced right ventricular (RV) dysfunction, but key genes remain largely unclear. We here identified HMOX1 as an essential ferroptosis-related differentially expressed gene in PAH by bioinformatic analysis using FerrDb, GSE119754, and GSE3675 datasets, respectively. Notably, there were marked increases in HMOX1 and iron levels in RV of monocrotaline-induced PAH rats with reduced TAPSE levels. More importantly, treatment with ferrostatin-1 effectively attenuated RV hypertrophy, remodeling, myocardial fibrosis, and dysfunction in PAH rats. In cultured H9C2 cells and primary neonatal rat cardiomyocytes, pretreatment with ferrostatin-1 and knockdown HMOX1 by siRNA strikingly blunted hypoxia-induced promotion of lipid peroxidation, ferroptosis, and cardiomyocyte injury by potentiating glutathione (GSH) and nitric oxide signaling, respectively. In summary, ferrostatin-1 attenuates RV hypertrophy, fibrosis, and dysfunction in PAH by suppressing the HMOX1/GSH signaling. Targeting HMOX1 ferroptosis signaling functions as a potential therapeutic strategy for patients with PAH.

The role of rhIGF-1/BP3 in the prevention of pulmonary hypertension in bronchopulmonary dysplasia and its underlying mechanism.

BACKGROUND: This study aimed to determine whether postnatal treatment with recombinant human IGF-1 (rhIGF-1)/binding peptide 3 (BP3) ameliorates lung injury and prevents pulmonary hypertension (PH) in bronchopulmonary dysplasia (BPD) models. METHODS: We used two models of BPD in this study: one model that was associated with chorioamnionitis (CA), stimulated by intra-amniotic fluid and exposure to lipopolysaccharide (LPS), whereas the other was exposed to postnatal hyperoxia. Newborn rats were treated with rhIGF-1/BP3 (0.2 mg/Kg/d) or saline via intraperitoneal injection. The study endpoints included the wet/dry weight (W/D) ratio of lung tissues, radial alveolar counts (RACs), vessel density, right ventricular hypertrophy (RVH), lung resistance, and lung compliance. Hematoxylin and eosin (H&E) and Masson staining were used to evaluate the degree of lung injury and pulmonary fibrosis. IGF-1 and eNOS expression were detected using western blotting or quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). The levels of SP-C, E-cadherin, N-cadherin, FSP1, and Vimentin in the lung tissues were detected by immunofluorescence. RESULTS: LPS and hyperoxia treatment increased lung injury and pulmonary fibrosis, enhanced RVH and total respiratory resistance, and decreased RAC, pulmonary vascular density and pulmonary compliance in young mice (all p < 0.01). Simultaneously, LPS and hyperoxia induced an increase in epithelial-mesenchymal transition (EMT) in airway epithelial cells. However, rhIGF-1/BP3 treatment reduced lung injury and pulmonary fibrosis, decreased RVH and total respiratory resistance, and enhanced RAC, pulmonary vascular density and pulmonary compliance, as well as inhibited EMT in airway epithelial cells in LPS and hyperoxia treated mice. CONCLUSION: Postnatal rhIGF-1/BP3 treatment relieved the effects of LPS or hyperoxia on lung injury and prevented RVH, providing a promising strategy for the treatment of BPD.

Serotonin-deficient neonatal mice are not protected against the development of experimental bronchopulmonary dysplasia or pulmonary hypertension.

Serotonin (5-hydroxytryptamine, 5-HT) is a potent pulmonary vasoconstrictor and contributes to high pulmonary vascular resistance in the developing ovine lung. In experimental pulmonary hypertension (PH), pulmonary expression of tryptophan hydroxylase-1 (TPH1), the rate limiting enzyme in 5-HT synthesis, and plasma 5-HT are increased. 5-HT blockade increases pulmonary blood flow and prevents pulmonary vascular remodeling and PH in neonatal models of PH with bronchopulmonary dysplasia (BPD). We hypothesized that neonatal tph1 knock-out (KO) mice would be protected from hypoxia-induced alveolar simplification, decreased vessel density, and PH. Newborn wild-type (WT) and tph1 KO mice were exposed to normoxia or hypoxia for 2 weeks. Normoxic WT and KO mice exhibited similar alveolar development, pulmonary vascular density, right ventricular systolic pressures (RVSPs), and right heart size. Circulating (plasma and platelet) 5-HT decreased in both hypoxia-exposed WT and KO mice. Tph1 KO mice were not protected from hypoxia-induced alveolar simplification, decreased pulmonary vascular density, or right ventricular hypertrophy, but displayed attenuation to hypoxia-induced RVSP elevation compared with WT mice. Tph1 KO neonatal mice are not protected against hypoxia-induced alveolar simplification, reduction in pulmonary vessel density, or RVH. While genetic and pharmacologic inhibition of tph1 has protective effects in adult models of PH, our results suggest that tph1 inhibition would not be beneficial in neonates with PH associated with BPD.

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.

Sildenafil prevents right ventricular hypertrophy and improves heart rate variability in rats with pulmonary hypertension secondary to experimental diabetes.

Chronic treatment with sildenafil (SILD) is an effective protector on the development of cardiovascular complications of pulmonary hypertension (PH) and diabetes. However, to date, no studies have evaluated the effect of SILD on cardiopulmonary pathophysiology during PH secondary to type 1 diabetes. AIM: The present study aimed to evaluate the beneficial effects of chronic SILD treatment on pulmonary arterial pressure, right ventricular hypertrophy (RVH) and cardiac autonomic dysfunction in rats with PH secondary to diabetes. METODOLOGY: Male Sprague Dawley rats were randomly distributed into the control group (saline), diabetic group (60 mg/kg with streptozotocin), SILD-treated control group (20 mg/kg) and SILD-treated diabetic group. RESULTS: After 8 weeks the type 1 diabetic animals presented PH, endothelial dysfunction of the pulmonary arteries, electrocardiographic alterations, RVH and overexpression of phosphodiesterase type 5 in the heart. In type 1 diabetic animals, SILD treatment prevented the development of PH, endothelial dysfunction and RVH. SILD treatment also prevented alterations in the corrected QT period and heart rate variability and prevented overexpression of phosphodiesterase type 5. CONCLUSION: Our results indicate for the first time that SILD treatment prevents pulmonary arterial endothelial dysfunction, pulmonary hypertension, right ventricular hypertrophy and improves heart rate variability in type 1 diabetic rats.

Bioactive Compounds From Coptidis Rhizoma Alleviate Pulmonary Arterial Hypertension by Inhibiting Pulmonary Artery Smooth Muscle Cells' Proliferation and Migration.

ABSTRACT: Pulmonary arterial hypertension (PAH) is a devastating disorder characterized by excessive proliferation and vasoconstriction of small pulmonary artery vascular smooth muscle cells (PASMCs). Coptidis rhizoma (CR) because of the complexity of the components, the underlying pharmacological role and mechanism of it on PAH remains unknown. In this article, the network pharmacological analysis was used to screen the main active constituents of CR and the molecular targets that these constituents act on. Then, we evaluated the importance of berberine and quercetin (biologically active components of CR) on the proliferation and migration of PASMCs and vascular remodeling in experimental models of PAH. Our results showed that berberine and quercetin effectively inhibited the proliferation and migration of hypoxia-induced PASMCs in a manner likely to be mediated by the suppression of MAPK1, NADPH oxidase 4 (NOX4), and cytochrome P450 1B1 (CYP1B1) expression. Furthermore, berberine and quercetin treatment attenuates pulmonary hypertension, reduces right ventricular hypertrophy, and improves pulmonary artery remodeling in monocrotaline-induced pulmonary hypertension in rat models. In conclusion, this research demonstrates CR might be a promising treatment option for PAH, and the network pharmacology approach can be an effective tool to reveal the potential mechanisms of Chinese herbal medicine.

Cystamine Treatment Fails to Prevent the Development of Pulmonary Hypertension in Chronic Hypoxic Rats.

INTRODUCTION: Pulmonary hypertension is characterized by vasoconstriction and remodeling of pulmonary arteries, leading to right ventricular hypertrophy and failure. We have previously found upregulation of transglutaminase 2 (TG2) in the right ventricle of chronic hypoxic rats. The hypothesis of the present study was that treatment with the transglutaminase inhibitor, cystamine, would inhibit the development of pulmonary arterial remodeling, pulmonary hypertension, and right ventricular hypertrophy. METHODS: Effect of cystamine on transamidase activity was investigated in tissue homogenates. Wistar rats were exposed to chronic hypoxia and treated with vehicle, cystamine (40 mg/kg/day in mini-osmotic pumps), sildenafil (25 mg/kg/day), or the combination for 2 weeks. RESULTS: Cystamine concentration-dependently inhibited TG2 transamidase activity in liver and lung homogenates. In contrast to cystamine, sildenafil reduced right ventricular systolic pressure and hypertrophy and decreased pulmonary vascular resistance and muscularization in chronic hypoxic rats. Fibrosis in the lung tissue decreased in chronic hypoxic rats treated with cystamine. TG2 expression was similar in the right ventricle and lung tissue of drug and vehicle-treated hypoxic rats. DISCUSSION/CONCLUSIONS: Cystamine inhibited TG2 transamidase activity, but cystamine failed to prevent pulmonary hypertension, right ventricular hypertrophy, and pulmonary arterial muscularization in the chronic hypoxic rat.

Soluble guanylate cyclase stimulator, trans-4-methoxy-ß-nitrostyrene, has a beneficial effect in monocrotaline-induced pulmonary arterial hypertension in rats.

The soluble guanylate cyclase (sGC)/GMPc pathway plays an important role in controlling pulmonary arterial hypertension (PAH). We investigated whether the novel sGC stimulator trans-4-methoxy-ß-nitrostyrene (T4MN), ameliorates monocrotaline (MCT)-induced PAH. At Day 0, rats were injected with MCT (60 mg/kg, s. c.). Control (CNT) rats received an equal volume of monocrotaline vehicle only (s.c.). Four weeks later, MCT-treated rats were orally treated for 14 days with T4MN (75 mg/kg/day) (MCT-T4MN group) or its vehicle (MCT-V group), and with sildenafil (SIL; 50 mg/kg) (MCT-SIL group). Compared to the CNT group, MCT treatment induced a significant increase in both the Fulton index and RV systolic pressure but significantly reduced the maximum relaxation induced by acetylcholine. Indeed, MCT treatment increased the wall thickness of small and larger pulmonary arterioles. Oral treatment with T4MN and SIL reduced the Fulton index and RV systolic pressure compared to the MCT-V group. Maximum relaxation induced by acetylcholine was significantly enhanced in MCT-SIL group. Both T4MN and SIL significantly reduced the enhanced wall thickness of small and larger pulmonary arterioles. Treatment with T4MN has a beneficial effect on PAH by reducing RV systolic pressure and consequently right ventricular hypertrophy, and by reducing pulmonary artery remodeling. T4MN may represent a new therapeutic or complementary approach for the treatment of PAH.

Angiotensin II type 1 receptor mediates pulmonary hypertension and right ventricular remodeling induced by inhaled nicotine.

Use of electronic cigarettes is rapidly increasing among youth and young adults, but little is known regarding the long-term cardiopulmonary health impacts of these nicotine-containing devices. Our group has previously demonstrated that chronic, inhaled nicotine induces pulmonary hypertension (PH) and right ventricular (RV) remodeling in mice. These changes were associated with upregulated RV angiotensin-converting enzyme (ACE). Angiotensin II receptor blockers (ARBs) have been shown to reverse cigarette smoking-induced PH in rats. ACE inhibitor and ARB use in a large retrospective cohort of patients with PH is associated with improved survival. Here, we utilized losartan (an ARB specific for angiotensin II type 1 receptor) to further explore nicotine-induced PH. Male C57BL/6 mice received nicotine vapor for 12 h/day, and exposure was assessed using serum cotinine to achieve levels comparable to human smokers or electronic cigarette users. Mice were exposed to nicotine for 8 wk and a subset was treated with losartan via an osmotic minipump. Cardiac function was assessed using echocardiography and catheterization. Although nicotine exposure increased angiotensin II in the RV and lung, this finding was nonsignificant. Chronic, inhaled nicotine significantly increased RV systolic pressure and RV free wall thickness versus air control. These parameters were significantly lower in mice receiving both nicotine and losartan. Nicotine significantly increased RV internal diameter, with no differences seen between the nicotine and nicotine-losartan group. Neither nicotine nor losartan affected left ventricular structure or function. These findings provide the first evidence that antagonism of the angiotensin II type 1 receptor can ameliorate chronic, inhaled nicotine-induced PH and RV remodeling.NEW & NOTEWORTHY Chronic, inhaled nicotine causes pulmonary hypertension and right ventricular remodeling in mice. Treatment with losartan, an angiotensin II type 1 receptor antagonist, ameliorates nicotine-induced pulmonary hypertension and right ventricular remodeling. This novel finding provides preclinical evidence for the use of renin-angiotensin system-based therapies in the treatment of pulmonary hypertension, particularly in patients with a history of tobacco-product use.

Continuous Aerobic Exercise Prevents Detrimental Remodeling and Right Heart Myocyte Contraction and Calcium Cycling Dysfunction in Pulmonary Artery Hypertension.

ABSTRACT: Pulmonary artery hypertension (PAH) imposes right heart and lung detrimental remodeling which impairs cardiac contractility, physical effort tolerance, and survival. The effects of an early moderate-intensity continuous aerobic exercise training on the right ventricle and lung structure, and on contractility and the calcium (Ca2+) transient in isolated myocytes from rats with severe PAH induced by monocrotaline were analyzed. Rats were divided into control sedentary (CS), control exercise (CE), monocrotaline sedentary (MS), and monocrotaline exercise (ME) groups. Animals from control exercise and ME groups underwent a moderate-intensity aerobic exercise on a treadmill (60 min/d; 60% intensity) for 32 days, after a monocrotaline (60 mg/kg body weight i.p.) or saline injection. The pulmonary artery resistance was higher in MS than in control sedentary (1.36-fold) and was reduced by 39.39% in ME compared with MS. Compared with MS, the ME group presented reduced alveolus (17%) and blood vessel (46%) wall, fibrosis (25.37%) and type I collagen content (55.78%), and increased alveolus (52.96%) and blood vessel (146.97%) lumen. In the right ventricle, the ME group exhibited diminished hypertrophy index (25.53%) and type I collagen content (40.42%) and improved myocyte contraction [ie, reduced times to peak (29.27%) and to 50% relax (13.79%)] and intracellular Ca2+ transient [ie, decreased times to peak (16.06%) and to 50% decay (7.41%)] compared with MS. Thus, early moderate-intensity continuous aerobic exercise prevents detrimental remodeling in the right heart and lung increases in the pulmonary artery resistance and dysfunction in single myocyte contraction and Ca2+ cycling in this model.

Estrogen receptor-α prevents right ventricular diastolic dysfunction and fibrosis in female rats.

Although women are more susceptible to pulmonary arterial hypertension (PAH) than men, their right ventricular (RV) function is better preserved. Estrogen receptor-α (ERα) has been identified as a likely mediator for estrogen protection in the RV. However, the role of ERα in preserving RV function and remodeling during pressure overload remains poorly understood. We hypothesized that loss of functional ERα removes female protection from adverse remodeling and is permissive for the development of a maladapted RV phenotype. Male and female rats with a loss-of-function mutation in ERα (ERαMut) and wild-type (WT) littermates underwent RV pressure overload by pulmonary artery banding (PAB). At 10 wk post-PAB, WT and ERαMut demonstrated RV hypertrophy. Analysis of RV pressure waveforms demonstrated RV-pulmonary vascular uncoupling and diastolic dysfunction in female, but not male, ERαMut PAB rats. Similarly, female, but not male, ERαMut exhibited increased RV fibrosis, comprised primarily of thick collagen fibers. There was an increased protein expression ratio of TIMP metallopeptidase inhibitor 1 (Timp1) to matrix metalloproteinase 9 (Mmp9) in female ERαMut compared with WT PAB rats, suggesting less collagen degradation. RNA-sequencing in female WT and ERαMut RV revealed kallikrein-related peptidase 10 (Klk10) and Jun Proto-Oncogene (Jun) as possible mediators of female RV protection during PAB. In summary, ERα in females is protective against RV-pulmonary vascular uncoupling, diastolic dysfunction, and fibrosis in response to pressure overload. ERα appears to be dispensable for RV adaptation in males. ERα may be a mediator of superior RV adaptation in female patients with PAH.NEW & NOTEWORTHY Using a novel loss-of-function mutation in estrogen receptor-α (ERα), we demonstrate that female, but not male, ERα mutant rats display right ventricular (RV)-vascular uncoupling, diastolic dysfunction, and fibrosis following pressure overload, indicating a sex-dependent role of ERα in protecting against adverse RV remodeling. TIMP metallopeptidase inhibitor 1 (Timp1), matrix metalloproteinase 9 (Mmp9), kallikrein-related peptidase 10 (Klk10), and Jun Proto-Oncogene (Jun) were identified as potential mediators in ERα-regulated pathways in RV pressure overload.

Resistance training prevents right ventricle hypertrophy in rats exposed to secondhand cigarette smoke.

Exposure to secondhand cigarette smoke is associated with the development of diverse diseases. Resistance training has been considered one of the most useful tools for patients with pulmonary disease, improving their quality of life. This study aimed to evaluate the effect of resistance training (RT) on the prevention of thickening of the right ventricle wall of rats exposed to secondhand cigarette smoke. Thirty-two Wistar rats were divided into four groups: Control (C), Smoker (S), Exercised (E) and Exercised Smoker (ES). The smoker groups were exposed to the smoke of four cigarettes for 30 min, twice daily, five days a week, for 16 weeks. The exercised groups climbed on a vertical ladder with progressive load, once a day, five days a week, for 16 weeks. The heart, trachea, lung, liver and gastrocnemius muscle were removed for histopathological analysis. Pulmonary emphysema (S and ES vs C and E, P < 0.0001) and pulmonary artery thickness enlargement (S vs C and E, P = 0.003, ES vs C, P = 0.003) were detected in the smoking groups. There was an increase in the right ventricle thickness in the S group compared with all other groups (P < 0.0001). An increase in resident macrophages in the liver was detected in both smoking groups compared with the C group (P = 0.002). Additionally, a relevant reduction of the diameter of the muscle fibers was detected only in ES compared with the C, S and E groups (P = 0.0002), impairing, at least in part, the muscle mass in exercised smoking rats. Therefore, it was concluded that resistance training prevented the increase of thickness of the right ventricle in rats exposed to secondhand cigarette smoke, but it may be not so beneficial for the skeletal muscle of smoking rats.

Angiotensin Receptor-Neprilysin Inhibition Attenuates Right Ventricular Remodeling in Pulmonary Hypertension.

BackgroundPulmonary hypertension (PH) results in increased right ventricular (RV) afterload and ventricular remodeling. Sacubitril/valsartan (sac/val) is a dual acting drug, composed of the neprilysin inhibitor sacubitril and the angiotensin receptor blocker valsartan, that has shown promising outcomes in reducing the risk of death and hospitalization for chronic systolic left ventricular heart failure. In this study, we aimed to examine if angiotensin receptor-neprilysin inhibition using sac/val attenuates RV remodeling in PH.Methods and ResultsRV pressure overload was induced in Sprague-Dawley rats via banding the main pulmonary artery. Three different cohorts of controls, placebo-treated PH, and sac/val-treated PH were studied in a 21-day treatment window. Terminal invasive hemodynamic measurements, quantitative histological analysis, biaxial mechanical testing, and constitutive modeling were employed to conduct a multiscale analysis on the effects of sac/val on RV remodeling in PH. Sac/val treatment decreased RV maximum pressures (29% improvement, P=0.002), improved RV contractile (30%, P=0.012) and relaxation (29%, P=0.043) functions, reduced RV afterload (35% improvement, P=0.016), and prevented RV-pulmonary artery uncoupling. Furthermore, sac/val attenuated RV hypertrophy (16% improvement, P=0.006) and prevented transmural reorientation of RV collagen and myofibers (P=0.011). The combined natriuresis and vasodilation resulting from sac/val led to improved RV biomechanical properties and prevented increased myofiber stiffness in PH (61% improvement, P=0.032).ConclusionsSac/val may prevent maladaptive RV remodeling in a pressure overload model via amelioration of RV pressure rise, hypertrophy, collagen, and myofiber reorientation as well as tissue stiffening both at the tissue and myofiber level.

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.

Gut Pathology and Its Rescue by ACE2 (Angiotensin-Converting Enzyme 2) in Hypoxia-Induced Pulmonary Hypertension.

Therapeutic advances for pulmonary hypertension (PH) have been incremental because of the focus on the pulmonary vasculature in PH pathology. Here, we evaluate the concept that PH is, rather, a systemic disorder involving interplay among multiorgan systems, including brain, gut, and lungs. Therefore, the objective of this study was to evaluate the hypothesis that PH is associated with a dysfunctional brain-gut-lung axis and that global overexpression of ACE2 (angiotensin-converting enzyme 2) rebalances this axis and protects against PH. ACE2 knockin and wild-type (WT; C57BL/6) mice were subjected to chronic hypoxia (10% FIO2) or room air for 4 weeks. Cardiopulmonary hemodynamics, histology, immunohistochemistry, and fecal 16S rRNA microbial gene analyses were evaluated. Hypoxia significantly increased right ventricular systolic pressure, sympathetic activity as well as the number and activation of microglia in the paraventricular nucleus of the hypothalamus in WT mice. This was associated with a significant increase in muscularis layer thickening and decreases in both villi length and goblet cells and altered gut microbiota. Global overexpression of ACE2 prevented changes in hypoxia-induced pulmonary and gut pathophysiology and established distinct microbial communities from WT hypoxia mice. Furthermore, WT mice subjected to fecal matter transfer from ACE2 knockin mice were resistant to hypoxia-induced PH compared with their controls receiving WT fecal matter transfer. These observations demonstrate that ACE2 ameliorates these hypoxia-induced pathologies and attenuates PH. The data implicate dysfunctional brain-gut-lung communication in PH and provide novel avenues for therapeutic interventions.

Chrysin Alleviates Monocrotaline-Induced Pulmonary Hypertension in Rats Through Regulation of Intracellular Calcium Homeostasis in Pulmonary Arterial Smooth Muscle Cells.

Chrysin (CH) is the main ingredient of many medicinal plants. Our previous study showed that CH could suppress hypoxia-induced pulmonary arterial smooth muscle cells proliferation and alleviate chronic hypoxia-induced pulmonary hypertension by targeting store-operated Ca entry (SOCE)-[Ca]i pathway. In this study, we investigated the effect of CH on monocrotaline-induced pulmonary hypertension (MCTPH) and the mechanism behind it. Results show that, in MCTPH model rats, (1) CH significantly reduced the enhancement of right ventricular pressure, right ventricular hypertrophy, and pulmonary vascular remodeling; (2) CH markedly suppressed the promotion of SOCE and [Ca]i in pulmonary arterial smooth muscle cells; and (3) CH obviously inhibited the MCT-upregulated proliferating cell nuclear antigen, TRPC1, TRPC4, and TRPC6 expression in distal pulmonary arteries. These results demonstrate that CH likely alleviates MCTPH by targeting TRPC1,4,6-SOCE-[Ca]i pathway.

Ursolic Acid Improves Monocrotaline-Induced Right Ventricular Remodeling by Regulating Metabolism.

Pulmonary arterial hypertension (PAH) is a progressive and malignant disease characterized by pulmonary small arteries and right ventricle (RV) remodeling that can lead to severe RV dysfunction and death. The current therapeutic targets for RV dysfunction, which is strongly linked to mortality, are far from adequate. Therefore, we investigated the effect of ursolic acid (UA), a pentacyclic triterpenoid carboxylic acid, on PAH-induced RV remodeling and its underlying mechanism. We established a PAH model by injecting Sprague Dawley rats with monocrotaline (MCT, 60 mg/kg, ip), as verified by echocardiography and hemodynamic examination. Proteomic analysis was performed on RV samples using a Q Exactive high-field mass spectrometer, followed by KEGG enrichment analysis. The effect of 4 weeks of UA (50 mg/kg) treatment on RV remodeling was explored based on ultrasound, hemodynamic parameters, and histological changes, with the mechanism verified in vivo and in vitro by qRT-PCR and western blotting. RV hypertrophy, fibrosis, increased apoptosis, and abnormal metabolism were induced by MCT and suppressed by UA via a mechanism that changed the expression of key markers. UA also attenuated the Phenylephrine-induced hypertrophy of neonatal rat ventricular myocytes and upregulated peroxisome proliferator-activated receptor-alpha (PPARα), a key fatty acid metabolism regulator, and its downstream factor carnitine palmitoyl transferase 1b. In conclusion, UA exerts beneficial effects on PAH-induced RV dysfunction and remodeling by regulating PPARα-dependent fatty acid metabolism.

Taurine prevents cardiomyocyte apoptosis by inhibiting the calpain-1/cytochrome c pathway during RVH in broilers.

The calpain-1-activated apoptotic pathway plays a key role in right ventricular hypertrophy (RVH). Taurine has been shown to attenuate apoptosis by inhibiting calpain activity. This experiment aimed to determine whether taurine could prevent RVH by inhibiting the calpain-1/cytochrome c apoptotic pathway. The broilers were given 1% taurine dissolved in drinking water and were raised at 10 °C ~ 12 °C from day 21 to day 42. At 21 d, 28 d, 35 d and 42 d, the right ventricular (RV) tissues were collected. Increased RVH index, angiotensin II, norepinephrine and atrial natriuretic peptide mRNA expression were reduced by taurine in the broiler RVs. Taurine obviously inhibited cardiomyocyte apoptosis via maintaining the mitochondrial membrane potential and decreased the activation of caspase-9 and caspase-3 in the broiler RVs. The antioxidant assay demonstrated that taurine enhanced the activities of superoxide dismutase, total antioxidant capacity and glutathione peroxidase and the glutathione/glutathione disulfide ratio. Western blot results revealed that taurine also downregulated the expression of calpain-1 and cytosolic cytochrome c while upregulating the expression of Bcl-2/Bax and mitochondrial cytochrome c in broiler cardiomyocytes during RVH. In summary, we found that taurine could enhance cardiomyocyte antioxidant ability and further prevented cardiomyocyte apoptosis by inhibiting the calpain-1/cytochrome c pathway during RVH in broilers.

The SGLT2 inhibitor empagliflozin reduces mortality and prevents progression in experimental pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a rare, but progressive and devastating vascular disease with few treatment options to prevent the advancement to right ventricular dysfunction hypertrophy and failure. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, enhances urinary glucose excretion as well as reduces cardiovascular events and mortality in individuals with type 2 diabetes. While empagliflozin has been reported to lower systemic hypertension due to increased diuresis, the effect of empagliflozin on PAH is unknown. We used monocrotaline (MCT)-treated Sprague-Dawley rats to determine if empagliflozin alters PAH-associated outcomes. Compared to vehicle control, daily empagliflozin administration significantly improved survival in rats with severe MCT-induced PAH. Hemodynamic assessments showed that empagliflozin treatment significantly reduced mean pulmonary artery pressure, right ventricular systolic pressure, and increased pulmonary acceleration time. Empagliflozin treatment resulted in reduced right ventricular hypertrophy and fibrosis. Histological and molecular assessments of lung vasculature revealed significantly reduced medial wall thickening and decreased muscularization of pulmonary arterioles after empagliflozin treatment compared to vehicle-treated rats. In summary, SGLT2 inhibition with empagliflozin lowered mortality, reduced right ventricle systolic pressure, and attenuated maladaptive pulmonary remodeling in MCT-induced PAH. Clinical studies evaluating the efficacy of SGLT-2 inhibition should be considered for patients with PAH.