Unraveling the Impact of miR-146a in Pulmonary Arterial Hypertension Pathophysiology and Right Ventricular Function.

Pulmonary arterial hypertension (PAH) is a chronic disorder characterized by excessive pulmonary vascular remodeling, leading to elevated pulmonary vascular resistance and right ventricle (RV) overload and failure. MicroRNA-146a (miR-146a) promotes vascular smooth muscle cell proliferation and vascular neointimal hyperplasia, both hallmarks of PAH. This study aimed to investigate the effects of miR-146a through pharmacological or genetic inhibition on experimental PAH and RV pressure overload animal models. Additionally, we examined the overexpression of miR-146a on human pulmonary artery smooth muscle cells (hPASMCs). Here, we showed that miR-146a genic expression was increased in the lungs of patients with PAH and the plasma of monocrotaline (MCT) rats. Interestingly, genetic ablation of miR-146a improved RV hypertrophy and systolic pressures in Sugen 5415/hypoxia (SuHx) and pulmonary arterial banding (PAB) mice. Pharmacological inhibition of miR-146a improved RV remodeling in PAB-wild type mice and MCT rats, and enhanced exercise capacity in MCT rats. However, overexpression of miR-146a did not affect proliferation, migration, and apoptosis in control-hPASMCs. Our findings show that miR-146a may play a significant role in RV function and remodeling, representing a promising therapeutic target for RV hypertrophy and, consequently, PAH.

Upregulation of Angiomotin-Like 2 Ameliorates Experimental Pulmonary Arterial Hypertension by Inactivating YAP1 Signaling.

ABSTRACT: Angiomotin-like 2 (AMOTL2) is related to numerous physiological and pathological conditions by affecting signal transduction. However, whether AMOTL2 is linked to pulmonary arterial hypertension (PAH) has not been addressed. This work aimed to investigate the potential role of AMOTL2 in PAH. A decrease in AMOTL2 abundance was observed in the lungs of PAH rats. The upregulation of AMOTL2 significantly decreased right ventricle systolic pressure and right ventricular hypertrophy in PAH rats. Overexpression of AMOTL2 also led to a noteworthy decrease in vascular wall thickness, pulmonary artery area, and collagen deposition in rats with PAH. AMOTL2 was downregulated in hypoxia-stimulated pulmonary arterial smooth muscle cells (PASMCs). Moreover, AMOTL2 overexpression impeded hypoxia-evoked proliferation, migration, and phenotypic transformation in rat PASMCs. Mechanistic investigation revealed that Yes-associated protein 1 (YAP1) activation in PAH rats or hypoxia-stimulated PASMCs was markedly inhibited by AMOTL2 overexpression, which was associated with increased large tumor suppressor 1/2 phosphorylation. The inhibition of large tumor suppressor 1/2 reversed the AMOTL2-mediated inactivation of YAP1. Restoring the activity of YAP1 reversed the inhibitory effect of AMOTL2 on hypoxia-evoked proliferation, migration, and phenotypic transformation of PASMCs. Collectively, these results suggest that AMOTL2 can ameliorate PAH in a rat model by interfering with pulmonary arterial remodeling via the inactivation of YAP1 signaling. Our work indicates that AMOTL2 may be a candidate target for novel drug development for the treatment of PAH.

Indigo Leaves-Induced Pulmonary Arterial Remodeling without Right Ventricular Hypertrophy in Rats.

Indigo naturalis (IN), derived from the leaves of the indigo plant, is a traditional Chinese medicine that has historically been used for its anti-inflammatory properties in the treatment of various diseases, including ulcerative colitis (UC). However, long-term use of IN in UC patients is incontrovertibly associated with the onset of pulmonary arterial hypertension (PAH). To investigate the mechanisms by which IN induces PAH, we focused on the raw material of IN, indigo leaves (IL). Only the condition of long-term chronic (6 months) and high-dose (containing 5% IL in the control diet) administration of IL induced medial thickening in the pulmonary arteries without right ventricular hypertrophy in our rat model. IL administration for a month did not induce pulmonary arterial remodeling but increased endothelin-1 (ET-1) expression levels within endothelial cell (EC) layers in the lungs. Gene Expression Omnibus analysis showed that ET-1 is a key regulator of PAH and that the IL component indican and its metabolite IS induced ET-1 mRNA expression via reactive oxygen species-dependent mechanism. We identified the roles of indican and IS in ET-1 expression in ECs, which were linked to pulmonary arterial remodeling in an animal model.

A Murine Model of Pressure Overload-Induced Right Ventricular Hypertrophy and Failure by Pulmonary Trunk Banding.

Right ventricular (RV) failure caused by pressure overload is strongly associated with morbidity and mortality in a number of cardiovascular and pulmonary diseases. The pathogenesis of RV failure is complex and remains inadequately understood. To identify new therapeutic strategies for the treatment of RV failure, robust and reproducible animal models are essential. Models of pulmonary trunk banding (PTB) have gained popularity, as RV function can be assessed independently of changes in the pulmonary vasculature. In this paper, we present a murine model of RV pressure overload induced by PTB in 5-week-old mice. The model can be used to induce different degrees of RV pathology, ranging from mild RV hypertrophy to decompensated RV failure. Detailed protocols for intubation, PTB surgery, and phenotyping by echocardiography are included in the paper. Furthermore, instructions for customizing instruments for intubation and PTB surgery are given, enabling fast and inexpensive reproduction of the PTB model. Titanium ligating clips were used to constrict the pulmonary trunk, ensuring a highly reproducible and operator-independent degree of pulmonary trunk constriction. The severity of PTB was graded by using different inner ligating clip diameters (mild: 450 µm and severe: 250 µm). This resulted in RV pathology ranging from hypertrophy with preserved RV function to decompensated RV failure with reduced cardiac output and extracardiac manifestations. RV function was assessed by echocardiography at 1 week and 3 weeks after surgery. Examples of echocardiographic images and results are presented here. Furthermore, results from right heart catheterization and histological analyses of cardiac tissue are shown.

ß-catenin mediates monocrotaline-induced pulmonary hypertension via glycolysis in rats.

BACKGROUND: Metabolic abnormalities and immune inflammation are deeply involved in pulmonary vascular remodelling and the development of pulmonary hypertension (PH). However, the regulatory mechanisms of glycolysis in macrophages are still elusive. Cumulative evidence indicates that ß-catenin plays a crucial role in metabolic reprogramming. This study aimed to investigate the effect of ß-catenin on macrophage glycolysis in PH. METHODS: LPS-induced BMDMs were generated via in vitro experiments. A monocrotaline (MCT)-induced PH rat model was established, and the ß-catenin inhibitor XAV939 was administered in vivo. The role of ß-catenin in glycolysis was analysed. The degree of pulmonary vascular remodelling was measured. RESULTS: ß-catenin was significantly increased in both in vitro and in vivo models. In LPS-induced BMDMs, ß-catenin increased the levels of hexokinase 2 (HK2), phosphofructokinase (PFK), M2-pyruvate kinase (PKM2), lactate dehydrogenase (LDH), and lactate (LA) and the expression of inflammatory cytokines and promoted PASMC proliferation and migration in vitro. XAV939 decreased the level of glycolysis and downregulated the expression of inflammatory cytokines in vivo. MCT promoted pulmonary arterial structural remodelling and right ventricular hypertrophy, and XAV939 alleviated these changes. CONCLUSIONS: Our findings suggest that ß-catenin is involved in the development of PH by promoting glycolysis and the inflammatory response in macrophages. Inhibition of ß-catenin could improve the progression of PH.

Simple model of pulmonary hypertension secondary to left heart pressure overload induced by partial intravascular occlusion of the ascending aorta.

Pulmonary hypertension is a group of diseases characterized by elevated pulmonary artery pressure and pulmonary vascular resistance with significant morbidity and mortality. The most prevalent type is pulmonary hypertension secondary to left heart disease (PH-LHD). The available experimental models of PH-LHD use partial pulmonary clamping by technically nontrivial open-chest surgery with lengthy recovery. We present a simple model in which the reduction of the cross-sectional area of the ascending aorta is achieved not by external clamping but by partial intravascular obstruction without opening the chest. In anesthetized rats, a blind polyethylene tubing was advanced from the right carotid artery to just above the aortic valve. The procedure is quick and easy to learn. Three weeks after the procedure, left heart pressure overload was confirmed by measuring left ventricular end-diastolic pressure by puncture (1.3 ± 0.2 vs. 0.4 ± 0.3 mmHg in controls, mean ± SD, P < 0.0001). The presence of pulmonary hypertension was documented by measuring pulmonary artery pressure by catheterization (22.3 ± 2.3 vs. 16.9 ± 2.7 mmHg, P = 0.0282) and by detecting right ventricular hypertrophy and increased muscularization of peripheral pulmonary vessels. Contributions of a precapillary vascular segment and vasoconstriction to the increased pulmonary vascular resistance were demonstrated, respectively, by arterial occlusion technique and by normalization of resistance by a vasodilator, sodium nitroprusside, in isolated lungs. These changes were comparable, but not additive, to those induced by an established pulmonary hypertension model, chronic hypoxic exposure. Intravascular partial aortic obstruction offers an easy model of pulmonary hypertension induced by left heart disease that has a vasoconstrictor and precapillary component.NEW & NOTEWORTHY We present a new, simple model of a clinically important type of pulmonary hypertension, that induced by left heart failure. Left ventricular pressure overload is induced in rats by inserting a blinded cannula into the ascending aorta via carotid artery access. This partial intravascular aortic obstruction, which does not require opening of the chest and prolonged recovery, causes pulmonary hypertension, which has a precapillary and vasoconstrictor as well as a vascular remodeling component.

Nur77 induced by HIF-1α mediates vascular remodeling in hypoxic pulmonary hypertension.

Nur77 is a member of the NR4A subfamily of orphan nuclear receptors that is expressed and has a function within the immune system. This study aimed to investigate the role of Nur77 in hypoxic pulmonary hypertension. SPF male SD rats were exposed in hypobaric chamber simulating 5000 m high altitude for 0, 3, 7, 14, 21 or 28 days. Rat pulmonary artery smooth muscle cells (RPASMCs) were cultured under normoxic conditions (5% CO2-95% ambient air) or hypoxic conditions (5% O2 for 6 h, 12 h, 24 h, 48 h). Hypoxic rats developed pulmonary arterial remodeling and right ventricular hypertrophy with significantly increased pulmonary arterial pressure. The levels of Nur77, HIF-1α and PNCA were upregulated in pulmonary arterial smooth muscle from hypoxic rats. Silencing of either Nur77 or HIF-1α attenuated hypoxia-induced proliferation. Silencing of HIF-1α down-regulated Nur77 protein level, but Nur77 silence did not reduce HIF-1α. Nur77 was not con-immunoprecipitated with HIF-1α. This study demonstrated that Nur77 acted as a downstream regulator of HIF-1α under hypoxia, and plays a critical role in the hypoxia-induced pulmonary vascular remodeling, which is regulated by HIF-1α. Nur77 maybe a novel target of HPH therapy.

Sex-dependent remodeling of right ventricular function in a rat model of pulmonary arterial hypertension.

Right ventricular (RV) function is an important prognostic indicator for pulmonary arterial hypertension (PAH), a vasculopathy that primarily and disproportionally affects women with distinct pre- and postmenopausal clinical outcomes. However, most animal studies have overlooked the impact of sex and ovarian hormones on RV remodeling in PAH. Here, we combined invasive measurements of RV hemodynamics and morphology with computational models of RV biomechanics in sugen-hypoxia (SuHx)-treated male, ovary-intact female, and ovariectomized female rats. Despite similar pressure overload levels, SuHx induced increases in end-diastolic elastance and passive myocardial stiffening, notably in male SuHx animals, corresponding to elevated diastolic intracellular calcium. Increases in end-systolic chamber elastance were largely explained by myocardial hypertrophy in male and ovary-intact female rats, whereas ovariectomized females exhibited contractility recruitment via calcium transient augmentation. Ovary-intact female rats primarily responded with hypertrophy, showing fewer myocardial mechanical alterations and less stiffening. These findings highlight sex-related RV remodeling differences in rats, affecting systolic and diastolic RV function in PAH.NEW & NOTEWORTHY Combining hemodynamic and morphological measurements from male, female, and ovariectomized female pulmonary arterial hypertension (PAH) rats revealed distinct adaptation mechanisms despite similar pressure overload. Males showed the most diastolic stiffening. Ovariectomized females had enhanced myocyte contractility and calcium transient upregulation. Ovary-intact females primarily responded with hypertrophy, experiencing milder passive myocardial stiffening and no changes in myocyte shortening. These findings suggest potential sex-specific pathways in right ventricular (RV) adaptation to PAH, with implications for targeted interventions.

Does Cell-Type-Specific Silencing of Monoamine Oxidase B Interfere with the Development of Right Ventricle (RV) Hypertrophy or Right Ventricle Failure in Pulmonary Hypertension?

Increased mitochondrial reactive oxygen species (ROS) formation is important for the development of right ventricular (RV) hypertrophy (RVH) and failure (RVF) during pulmonary hypertension (PH). ROS molecules are produced in different compartments within the cell, with mitochondria known to produce the strongest ROS signal. Among ROS-forming mitochondrial proteins, outer-mitochondrial-membrane-located monoamine oxidases (MAOs, type A or B) are capable of degrading neurotransmitters, thereby producing large amounts of ROS. In mice, MAO-B is the dominant isoform, which is present in almost all cell types within the heart. We analyzed the effect of an inducible cardiomyocyte-specific knockout of MAO-B (cmMAO-B KO) for the development of RVH and RVF in mice. Right ventricular hypertrophy was induced by pulmonary artery banding (PAB). RV dimensions and function were measured through echocardiography. ROS production (dihydroethidium staining), protein kinase activity (PamStation device), and systemic hemodynamics (in vivo catheterization) were assessed. A significant decrease in ROS formation was measured in cmMAO-B KO mice during PAB compared to Cre-negative littermates, which was associated with reduced activity of protein kinases involved in hypertrophic growth. In contrast to littermates in which the RV was dilated and hypertrophied following PAB, RV dimensions were unaffected in response to PAB in cmMAO-B KO mice, and no decline in RV systolic function otherwise seen in littermates during PAB was measured in cmMAO-B KO mice. In conclusion, cmMAO-B KO mice are protected against RV dilatation, hypertrophy, and dysfunction following RV pressure overload compared to littermates. These results support the hypothesis that cmMAO-B is a key player in causing RV hypertrophy and failure during PH.

PAI-1 deficiency drives pulmonary vascular smooth muscle remodeling and pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by vasoconstriction and remodeling of small pulmonary arteries (PAs). Central to the remodeling process is a switch of pulmonary vascular cells to a proliferative, apoptosis-resistant phenotype. Plasminogen activator inhibitors-1 and -2 (PAI-1 and PAI-2) are the primary physiological inhibitors of urokinase-type and tissue-type plasminogen activators (uPA and tPA), but their roles in PAH are unsettled. Here, we report that: 1) PAI-1, but not PAI-2, is deficient in remodeled small PAs and in early-passage PA smooth muscle and endothelial cells (PASMCs and PAECs) from subjects with PAH compared with controls; 2) PAI-1-/- mice spontaneously develop pulmonary vascular remodeling associated with upregulation of mTORC1 signaling, pulmonary hypertension (PH), and right ventricle (RV) hypertrophy; and 3) pharmacological inhibition of uPA in human PAH PASMCs suppresses proproliferative mTORC1 and SMAD3 signaling, restores PAI-1 levels, reduces proliferation, and induces apoptosis in vitro, and prevents the development of SU5416/hypoxia-induced PH and RV hypertrophy in vivo in mice. These data strongly suggest that downregulation of PAI-1 in small PAs promotes vascular remodeling and PH due to unopposed activation of uPA and consequent upregulation of mTOR and transforming growth factor-ß (TGF-ß) signaling in PASMCs, and call for further studies to determine the potential benefits of targeting the PAI-1/uPA imbalance to attenuate and/or reverse pulmonary vascular remodeling and PH.NEW & NOTEWORTHY This study identifies a novel role for the deficiency of plasminogen activator inhibitor (PAI)-1 and resultant unrestricted uPA activity in PASMC remodeling and PH in vitro and in vivo, provides novel mechanistic link from PAI-1 loss through uPA-induced Akt/mTOR and TGFß-Smad3 upregulation to pulmonary vascular remodeling in PH, and suggests that inhibition of uPA to rebalance the uPA-PAI-1 tandem might provide a novel approach to complement current therapies used to mitigate this pulmonary vascular disease.

Preparation of the new peptide drug ACTY116-loaded in situ forming implants and evaluation of its efficacy in pulmonary arterial hypertension and right ventricular hypertrophy induced by SU5416/hypoxia in mice.

There is a lack of effective therapeutic drugs for pulmonary arterial hypertension. Previous studies have demonstrated the positive cardiovascular system protective effects of the new peptide ACTY116. However, its stability in ordinary aqueous solution injections is poor and its half-life in the body is short, which has hindered the development of preparations. This study aimed to prepare in situ forming implants (ISFIs) of the peptide ACTY116 and investigate its impact on pulmonary arterial hypertension. We prepared ISFIs using NMP/TA as a solvent and PLGA as a polymer. These ISFIs exhibited low viscosity, low toxicity and sustained release properties. In a mouse model of pulmonary hypertension induced by SU5416/hypoxia, both ISFIs and ACTY116 peptides effectively reduced pulmonary hypertension, cardiac hypertrophy and pulmonary blood vessel wall thickness. In conclusion, this study highlights the potential of ACTY116 as a treatment for pulmonary arterial hypertension and suggests that incorporating it into an in-situ gel implant could be a promising option.

Mechanisms of cordycepin in the treatment of pulmonary arterial hypertension in rats based on metabonomics and transcriptomics.

Pulmonary arterial hypertension (PAH) is a fatal disease featured by high morbidity and mortality. Although Cordycepin is known for its anti-inflammatory, antioxidant and immune-enhancing effects, its role in PAH treatment and the underlying mechanisms remain unclear. The therapeutic effects of Cordycepin on rats with PAH were investigated using a monocrotaline (MCT)-induced rat model. The metabolic effects of Cordycepin were assessed based on the plasma metabolome. The potential mechanisms of Cordycepin in PAH treatment were investigated through transcriptome sequencing and validated in pulmonary artery smooth muscle cells (PASMC). Evaluations included hematoxylin and eosin staining for pulmonary vascular remodeling, CCK-8 assay, EDU, and TUNEL kits for cell viability, proliferation, and apoptosis, respectively, and western blot for protein expression. Cordycepin significantly reduced right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) in PAH rats, and mitigated pulmonary vascular remodeling. Plasma metabolomics showed that Cordycepin could reverse the metabolic disorders in the lungs of MCT-induced PAH rats, particularly impacting linoleic acid and alpha-linolenic acid metabolism pathways. Transcriptomics revealed that the P53 pathway might be the primary pathway involved, and western blot results showed that Cordycepin significantly increased P53 and P21 protein levels in lung tissues. Integrated analysis of transcriptomics and metabolomics suggested that these pathways were mainly enriched in linoleic acid metabolism and alpha-linolenic acid metabolism pathway. In vitro experiments demonstrated that Cordycepin significantly inhibited the PDGFBB (PD)-induced abnormal proliferation and migration of PASMC and promoted PD-induced apoptosis. Meanwhile, Cordycepin enhanced the expression levels of P53 and P21 proteins in PD-insulted PASMC. However, inhibitors of P53 and P21 eliminated these effects of Cordycepin. Cordycepin may activate the P53-P21 pathway to inhibit abnormal proliferation and migration of PASMC and promote apoptosis, offering a potential approach for PAH treatment.

Bawei Chenxiang Wan ameliorates right ventricular hypertrophy in rats with high altitude heart disease by SIRT3-HIF1α-PDK/PDH signaling pathway improving fatty acid and glucose metabolism.

BACKGROUND: Bawei Chenxiang Wan (BCW) is among the most effective and widely used therapies for coronary heart disease and angina pectoris in Tibet. However, whether it confers protection through a right-ventricle (RV) myocardial metabolic mechanism is unknown. METHODS: Male Sprague-Dawley rats were orally administrated with BCW, which was injected concurrently with a bolus of Sugen5416, and subjected to hypoxia exposure (SuHx; 5000 m altitude) for 4 weeks. Right ventricular hypertrophy (RVH) in high-altitude heart disease (HAHD) was assessed using Fulton's index (FI; ratio of RV to left ventricle + septum weights) and heart-weight-to-body-weight ratio (HW/BW). The effect of therapeutic administration of BCW on the RVH hemodynamics was assessed through catheterization (mean right ventricular pressure and mean pulmonary artery pressure (mRVP and mPAP, respectively)). Tissue samples were used to perform histological staining, and confirmatory analyses of mRNA and protein levels were conducted to detect alterations in the mechanisms of RVH in HAHD. The protective mechanism of BCW was further verified via cell culture. RESULTS: BCW considerably reduced SuHx-associated RVH, as indicated by macro morphology, HW/BW ratio, FI, mPAP, mRVP, hypertrophy markers, heart function, pathological structure, and myocardial enzymes. Moreover, BCW can alleviate the disorder of glucose and fatty acid metabolism through upregulation of carnitine palmitoyltransferase1ɑ, citrate synthase, and acetyl-CoA and downregulation of glucose transport-4, phosphofructokinase, and pyruvate, which resulted in the reduced levels of free fatty acid and lactic acid and increased aerobic oxidation. This process may be mediated via the regulation of sirtuin 3 (SIRT3)-hypoxia-inducible factor 1α (HIF1α)-pyruvate dehydrogenase kinase (PDK)/pyruvate dehydrogenase (PDH) signaling pathway. Subsequently, the inhibition of SIRT3 expression by 3-TYP (a selective inhibitor of SIRT3) can reverse substantially the anti-RVH effect of BCW in HAHD, as indicated by hypertrophy marker and serum myocardial enzyme levels. CONCLUSIONS: BCW prevented SuHx-induced RVH in HAHD via the SIRT3-HIF1ɑ-PDK/PDH signaling pathway to alleviate the disturbance in fatty acid and glucose metabolism. Therefore, BCW can be used as an alternative drug for the treatment of RVH in HAHD.

Echocardiographic features of right ventricle in septic patients with elevated central venous pressure.

BACKGROUND: Elevated central venous pressure (CVP) is deemed as a sign of right ventricular (RV) dysfunction. We aimed to characterize the echocardiographic features of RV in septic patients with elevated CVP, and quantify associations between RV function parameters and 30-day mortality. METHODS: We retrospectively reviewed a cohort of septic patients with CVP ≥ 8 mmHg in a tertiary hospital intensive care unit. General characteristics and echocardiographic parameters including tricuspid annular plane systolic excursion (TAPSE), pulmonary vascular resistance (PVR) as well as prognostic data were collected. Associations between RV function parameters and 30-day mortality were assessed using Cox regression models. RESULTS: Echocardiography was performed in 244 septic patients with CVP ≥ 8 mmHg. Echocardiographic findings revealed that various types of abnormal RV function can occur individually or collectively. Prevalence of RV systolic dysfunction was 46%, prevalence of RV enlargement was 34%, and prevalence of PVR increase was 14%. In addition, we collected haemodynamic consequences and found that prevalence of systemic venous congestion was 16%, prevalence of RV-pulmonary artery decoupling was 34%, and prevalence of low cardiac index (CI) was 23%. The 30-day mortality of the enrolled population was 24.2%. In a Cox regression analysis, TAPSE (HR:0.542, 95% CI:0.302-0.972, p = 0.040) and PVR (HR:1.384, 95% CI:1.007-1.903, p = 0.045) were independently associated with 30-day mortality. CONCLUSIONS: Echocardiographic findings demonstrated a high prevalence of RV-related abnormalities (RV enlargement, RV systolic dysfunction and PVR increase) in septic patients with elevated CVP. Among those echocardiographic parameters, TAPSE and PVR were independently associated with 30-day mortality in these patients.

Hypoxia-Induced Myocardial Hypertrophy Companies with Apoptosis Enhancement and p38-MAPK Pathway Activation.

Li, Xiaoxu, Zhijun Pu, Gang Xu, Yidong Yang, Yu Cui, Xiaoying Zhou, Chenyuan Wang, Zhifeng Zhong, Simin Zhou, Jun Yin, Fabo Shan, Chengzhong Yang, Li Jiao, Dewei Chen, and Jian Huang. Hypoxia-induced myocardial hypertrophy companies with apoptosis enhancement and p38-MAPK pathway activation. High Alt Med Biol. 25:186-196, 2024. Background: Right ventricular function and remodeling are closely associated with symptom severity and patient survival in hypoxic pulmonary hypertension. However, the detailed molecular mechanisms underlying hypoxia-induced myocardial hypertrophy remain unclear. Methods: In Sprague-Dawley rats, hemodynamics were assessed under both normoxia and hypobaric hypoxia at intervals of 7 (H7), 14 (H14), and 28 (H28) days. Morphological changes in myocardial tissue were examined using hematoxylin and eosin (HE) staining, while myocardial hypertrophy was evaluated with wheat germ agglutinin (WGA) staining. Apoptosis was determined through TUNEL assays. To further understand the mechanism of myocardial hypertrophy, RNA sequencing was conducted, with findings validated via Western blot analysis. Results: The study demonstrated increased hypoxic pulmonary hypertension and improved right ventricular diastolic and systolic function in the rat models. Significant elevations in pulmonary arterial systolic pressure (PASP), mean pulmonary arterial pressure (mPAP), right ventricular mean pressure (RVMP), and the absolute value of +dp/dtmax were observed in the H14 and H28 groups compared with controls. In addition, right ventricular systolic pressure (RVSP), -dp/dtmax, and the mean dp/dt during isovolumetric relaxation period were notably higher in the H28 group. Heart rate increased in the H14 group, whereas the time constant of right ventricular isovolumic relaxation (tau) was reduced in both H14 and H28 groups. Both the right heart hypertrophy index and the heart weight/body weight ratio (HW/BW) were elevated in the H14 and H28 groups. Myocardial cell cross-sectional area also increased, as shown by HE and WGA staining. Western blot results revealed upregulated HIF-1α levels and enhanced HIF-2α expression in the H7 group. In addition, phosphorylation of p38 and c-fos was augmented in the H28 group. The H28 group showed elevated levels of Cytochrome C (Cyto C), whereas the H14 and H28 groups exhibited increased levels of Cleaved Caspase-3 and the Bax/Bcl-2 ratio. TUNEL analysis revealed a rise in apoptosis with the extension of hypoxia duration in the right ventricle. Conclusions: The study established a link between apoptosis and p38-MAPK pathway activation in hypoxia-induced myocardial hypertrophy, suggesting their significant roles in this pathological process.

Metabolic changes contribute to maladaptive right ventricular hypertrophy in pulmonary hypertension beyond pressure overload: an integrative imaging and omics investigation.

Right ventricular (RV) failure remains the strongest determinant of survival in pulmonary hypertension (PH). We aimed to identify relevant mechanisms, beyond pressure overload, associated with maladaptive RV hypertrophy in PH. To separate the effect of pressure overload from other potential mechanisms, we developed in pigs two experimental models of PH (M1, by pulmonary vein banding and M2, by aorto-pulmonary shunting) and compared them with a model of pure pressure overload (M3, pulmonary artery banding) and a sham-operated group. Animals were assessed at 1 and 8 months by right heart catheterization, cardiac magnetic resonance and blood sampling, and myocardial tissue was analyzed. Plasma unbiased proteomic and metabolomic data were compared among groups and integrated by an interaction network analysis. A total of 33 pigs completed follow-up (M1, n = 8; M2, n = 6; M3, n = 10; and M0, n = 9). M1 and M2 animals developed PH and reduced RV systolic function, whereas animals in M3 showed increased RV systolic pressure but maintained normal function. Significant plasma arginine and histidine deficiency and complement system activation were observed in both PH models (M1&M2), with additional alterations to taurine and purine pathways in M2. Changes in lipid metabolism were very remarkable, particularly the elevation of free fatty acids in M2. In the integrative analysis, arginine-histidine-purines deficiency, complement activation, and fatty acid accumulation were significantly associated with maladaptive RV hypertrophy. Our study integrating imaging and omics in large-animal experimental models demonstrates that, beyond pressure overload, metabolic alterations play a relevant role in RV dysfunction in PH.

Sulforaphane Improves Redox Homeostasis and Right Ventricular Contractility in a Model of Pulmonary Hypertension.

ABSTRACT: Pulmonary arterial hypertension (PAH) is characterized by increased pulmonary vascular resistance (PVR), imposing overload on the right ventricle (RV) and imbalance of the redox state. Our study investigated the influence of treatment with sulforaphane (SFN), found in cruciferous vegetables, on RV remodeling and redox homeostasis in monocrotaline (MCT)-induced PAH. Male Wistar rats were separated into 4 groups: control (CTR); CTR + SFN; MCT; and MCT + SFN. PAH induction was implemented by a single dose of MCT (60 mg/kg intraperitoneally). Treatment with SFN (2.5 mg/kg/day intraperitoneally) started on the seventh day after the MCT injection and persisted for 2 weeks. After 21 days of PAH induction, echocardiographic, hemodynamic, and oxidative stress evaluation was performed. The MCT group showed an increase in RV hypertrophy, RV systolic area, RV systolic, mean pulmonary artery pressure, and PVR and exhibited a decrease in the RV outflow tract acceleration time/ejection time ratio, RV fractional shortening, and tricuspid annular plane systolic excursion compared to CTR ( P < 0.05). SFN-treated PAH attenuated detrimental changes in tricuspid annular plane systolic excursion, mean pulmonary artery pressure, and PVR parameters. Catalase levels and the glutathione/Glutathione disulfide (GSSG) ratio were diminished in the MCT group compared to CTR ( P < 0.05). SFN increased catalase levels and normalized the glutathione/GSSG ratio to control levels ( P < 0.05). Data express the benefit of SFN treatment on the cardiac function of rats with PAH associated with the cellular redox state.

Effect of free and nanoemulsified ß-caryophyllene on monocrotaline-induced pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is characterized by increased pulmonary vascular resistance (PVR), right ventricular (RV) failure and premature death. Compounds with vasodilatory characteristics, such as ß-caryophyllene, could be promising therapeutics for PAH. This study aimed to determine the effects of free and nanoemulsified ß-caryophyllene in lung oxidative stress and heart function in PAH rats. Male Wistar rats (170 g, n = 6/group) were divided into four groups: control (CO), monocrotaline (MCT), monocrotaline + ß-caryophyllene (MCT-Bcar) and monocrotaline + nanoemulsion with ß-caryophyllene (MCT-Nano). PAH was induced by MCT (60 mg/kg i.p.), and 7 days later, treatment with ß-caryophyllene, either free or in a nanoemulsion (by gavage, 176 mg/kg/day) or vehicle was given for 14 days. Echocardiographic and hemodynamic measurements were performed, and after, the RV was collected for morphometry and the lungs for evaluation of oxidative stress, antioxidant enzymes, total sulfhydryl compounds, nitric oxide synthase (NOS) activity and endothelin-1 receptor expression. RV hypertrophy, increased PVR and RV systolic and diastolic pressures (RVSP and RVEDP, respectively) and increased mean pulmonary arterial pressure (mPAP) were observed in the MCT group. Treatment with both free and nanoemulsified ß-caryophyllene reduced RV hypertrophy, mPAP, RVSP and lipid peroxidation. The reduction in RVSP was more pronounced in the MCT-Nano group. Moreover, RVEDP decreased only in the MCT-Nano group. These treatments also increased superoxide dismutase, catalase and NOS activities and decreased endothelin-1 receptors expression. Both ß-caryophyllene formulations improved mPAP, PVR and oxidative stress parameters. However, ß-caryophyllene in a nanoemulsion was more effective in attenuating the effects of PAH.

[Effects of human umbilical cord mesenchymal stem cells (MSCs)-derived exosomes on pulmonary vascular remodeling in hypoxic pulmonary hypertension].

The present study aimed to investigate the effect of human umbilical cord mesenchymal stem cells (MSCs)-derived exosomes (MSCs-Exo) on mice with hypoxic pulmonary hypertension (HPH). MSCs were isolated and cultured from human umbilical cords under aseptic conditions, and exosomes were extracted from the supernatants and identified. Healthy SPF C57BL/6 mice were randomly divided into three groups: normoxic group, hypoxic group, and hypoxic+MSCs-Exo group. Mice in the hypoxic group and the hypoxic+MSCs-Exo group were maintained for 28 d at an equivalent altitude of 5 000 m in a hypobaric chamber to establish HPH mouse model. The mice in the hypoxic+MSCs-Exo group were injected with MSCs-Exo via tail vein before hypoxia and on days 1, 3, 5 and 9 of hypoxia, and the mice in the other two groups were injected with PBS. At the end of the experiment, echocardiography was performed to detect pulmonary arterial acceleration time/pulmonary arterial ejection time ratio (PAAT/PET), right ventricular free wall thickness, and right ventricular hypertrophy index RV/(LV+S). HE staining was performed to observe the lung tissue morphology. EVG staining was performed to observe elastic fiber hyperplasia. Immunohistochemistry was performed to detect α smooth muscle actin (α-SMA) expression in lung tissue. Immunofluorescence staining was used to detect macrophage infiltration in lung tissue. qPCR was performed to detect IL-1ß and IL-33 in lung tissue, and cytometric bead array was performed to detect IL-10 secretion. Western blotting was used to detect the M1 macrophage marker iNOS, M2 macrophage marker Arg-1 and IL-33/ST2 pathway proteins in lung tissues. The results showed that hypoxia increased pulmonary artery pressure and pulmonary vascular remodeling, increased macrophage infiltration, IL-1ß and IL-33 expression (P < 0.05) and upregulated the IL-33/ST2 pathway (P < 0.05). Compared with the hypoxic group, MSCs-Exo treatment increased PAAT/PET (P < 0.05), decreased right ventricular free wall thickness (P < 0.05), right ventricular hypertrophy index RV/(LV+S) (P < 0.05), α-SMA expression in small pulmonary vessels (P < 0.05), and inflammatory factors including IL-1ß and IL-33 expression in lung tissue, however increased IL-10 secretion (P < 0.05). In addition, MSCs-Exo treatment upregulated Arg-1 and downregulated iNOS and IL-33/ST2 (P < 0.05). The results suggest that MSC-Exo may alleviate HPH through their immunomodulatory effects.

Forsythoside B Mitigates Monocrotaline-Induced Pulmonary Arterial Hypertension via Blocking the NF-κB Signaling Pathway to Attenuate Vascular Remodeling.

Purpose: Pulmonary arterial hypertension (PAH) is a devastating disease with little effective treatment. The proliferation of pulmonary artery smooth muscle cells (PASMCs) induced by the nuclear factor-κB (NF-κB) signaling activation plays a pivotal role in the pathogenesis of PAH. Forsythoside B (FTS•B) possesses inhibitory effect on NF-κB signaling pathway. The present study aims to explore the effects and mechanisms of FTS•B in PAH. Methods: Sprague-Dawley rats received monocrotaline (MCT) intraperitoneal injection to establish PAH model, and FTS•B was co-treated after MCT injection. Right ventricular hypertrophy and pulmonary artery pressure were measured by echocardiography and right heart catheterization, respectively. Histological alterations were detected by H&E staining and immunohistochemistry. FTS•B's role in PASMC proliferation and migration were evaluated by CCK-8 and wound healing assay. To investigate the underlying mechanisms, Western blotting, immunofluorescence staining and ELISA were conducted. The NF-κB activator PMA was used to investigate the role of NF-κB in FTS•B's protective effects against PAH. Results: FTS•B markedly alleviated MCT-induced vascular remodeling and pulmonary artery pressure, and improved right ventricular hypertrophy and survival. FTS•B also reversed PDGF-BB-induced PASMC proliferation and migration, decreased PCNA and CyclinD1 expression in vitro. The elevated levels of IL-1ß and IL-6 caused by MCT were decreased by FTS•B. Mechanistically, MCT-triggered phosphorylation of p65, IκBα, IKKα and IKKß was blunted by FTS•B. FTS•B also reversed MCT-induced nuclear translocation of p65. However, all these protective effects were blocked by PMA-mediated NF-κB activation. Conclusion: FTS•B effectively attenuates PAH by suppressing the NF-κB signaling pathway to attenuate vascular remodeling. FTS•B might be a promising drug candidate with clinical translational potential for the treatment of PAH.