AMPK activation by metformin protects against pulmonary hypertension in rats and relaxes isolated human pulmonary artery

Deciphering the inhibitory effects of trimetazidine on pulmonary hypertension development via decreasing fatty acid oxidation and promoting glucose oxidation

Pulmonary hypertension (PH) is a devastating disease characterized by vascular remodeling, resulting in right ventricular failure and death. Dysregulation of energy metabolism is linked to PH pathogenesis. Trimetazidine (TMZ), a selective long-chain 3-ketoacyl coenzyme A thiolase inhibitor, is critical in maintaining energy metabolism. Despite the indicated TMZ's inhibitory effect on pulmonary vascular remodeling in PH development, the integrated evaluation of the changes in biomolecules, such as metabolites and transcripts, that TMZ induces in the lung and heart tissues is largely unknown in vivo. For an improved understanding of the molecular mechanism involving the effects of TMZ on PH development, we performed a comprehensive analysis of the changes in cardiac metabolites and pulmonary transcripts of SU5416-Hypoxia (Su/Hx) rats treated with TMZ. Metabolomic analysis of the Su/Hx-induced PH hearts demonstrated that TMZ reduced the long-chain fatty acid concentration. Additionally, TMZ alleviated PH degree and excessive strain on the right heart functions in rats with Su/Hx-induced PH. We identified the candidate target genes for TMZ treatment during PH development. Interestingly, the mRNA levels of the fatty acid transporters were substantially downregulated by TMZ administration in the lungs with Su/Hx-induced PH. Notably, TMZ suppressed excessive proliferation of human pulmonary artery smooth muscle cells under hypoxic conditions. Our study suggests that TMZ ameliorates PH development by involving energy metabolism in the lungs and heart.

Resistance artery vasodilator pathways involved in the antihypertensive effects of cocoa shell extract in rats exposed to fetal undernutrition

Fetal undernutrition establishes the foundations for hypertension development, with oxidative stress being a key hallmark. A growing interest in nutraceuticals for treating hypertension and environmental waste concerns prompted the present study aiming to evaluate whether supplementation with a polyphenol enriched extract from cocoa shell (CSE), a by-product from the chocolate industry with antioxidant properties, reduces hypertension of developmental origin, thus improving mesenteric resistance artery (MRA) vasodilatation. Adult male and female offspring from rats exposed to 50% food restriction from mid-gestation (maternal undernutrition, MUN) and controls were used. Supplementation was given through a gelatine (vehicle, VEH) or containing CSE (250 mg kg-1 day-1) 5 days week-1 for 3 weeks. Systolic blood pressure (SBP) was assessed by tail-cuff plethysmography. MRA function was studied by wire myography, and superoxide anion and nitric oxide were investigated by fluorescent indicators and confocal microscopy. Compared to control-VEH, MUN-VEH males showed significantly higher SBP, reduced MRA as well as relaxation to ACh, sodium nitroprusside and the AMPK agonist 5-aminoimidazole-4-carboxamide riboside, but not to isoproterenol. In MUN males, endothelial endothelium-derived hyperpolarizing factor and nitric oxide were unaltered, but MRA released a vasoconstrictor prostanoid and produced higher levels of superoxide anion. CSE normalized blood pressure and improved all above-mentioned MRA alterations in MUN males without an effect on control counterparts, except the reduction of superoxide anion. MUN-VEH females were normotensive and only showed a tendency towards larger superoxide anion production, which was abolished by CSE. CSE supplementation reduces SBP improving endothelium-dependent and independent MRA vasodilatation, related to local superoxide anion reduction, being a potential nutraceutical ingredient to counteract hypertension, in addition to contributing to the circular economy. KEY POINTS: Fetal undernutrition induces hypertension in males associated with deficient resistance artery vasodilatation, being normalized by cocoa shell extract (CSE). Release of a cyclooxygenase-derived contractile factor is the main endothelial alteration, which is abolished by CSE. AMPK and soluble guanylyl cyclase-mediated relaxation are also reduced in smooth muscle cells from maternal undernutrition resistance arteries, being improved by CSE. Vascular oxidative damage caused by excess superoxide anion generation can account for impaired vasodilatation, which is improved by CSE. The capacity of CSE to improve relaxation is probably related to its antioxidant bioactive factors, and thus cocoa shell is a potential food by-product to treat hypertension.

Resveratrol attenuates cyclosporin A-induced upregulation of the thromboxane A2 receptor and hypertension via the AMPK/SIRT1 and MAPK/NF-κB pathways in the rat mesenteric artery

Cyclosporin A, an immunosuppressive agent, is extensively utilized for the prevention of transplant rejection and treat autoimmune disease in the clinic, despite its association with a high risk of hypertension development among patients. Resveratrol is a kind of non-flavonoid phenolic compound that widely exists in many plants. The aim of the present study was to investigate the mechanism by which resveratrol ameliorates cyclosporin A-induced hypertension. The arterial rings of the mesentery were incubated with cyclosporin A and resveratrol in vitro. Rats were administered cyclosporin A and/or resveratrol for 3 weeks in vivo. Blood pressure was measured via the tail arteries. Vasoconstriction curves were recorded using a sensitive myograph. The protein expression was evaluated through Western blotting. This study demonstrated that resveratrol mitigated the cyclosporin A-induced increase in blood pressure in rats. Furthermore, resveratrol markedly inhibited the cyclosporin A-induced upregulation of thromboxane A2 receptor-mediated vasoconstriction in the rat mesenteric artery both in vitro and in vivo. Moreover, resveratrol activated AMPK/SIRT1 and inhibited the MAPK/NF-κB signaling pathway. In conclusion, resveratrol restored the cyclosporin A-induced upregulation of the thromboxane A2 receptor and hypertension via the AMPK/SIRT1 and MAPK/NF-κB pathways in rats.

Canagliflozin inhibits PASMCs proliferation via regulating SGLT1/AMPK signaling and attenuates artery remodeling in MCT-induced pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) was a devastating disease characterized by artery remodeling, ultimately resulting in right heart failure. The aim of this study was to investigate the effects of canagliflozin (CANA), a sodium-glucose cotransporter 2 inhibitor (SGLT2i) with mild SGLT1 inhibitory effects, on rats with PAH, as well as its direct impact on pulmonary arterial smooth muscle cells (PASMCs). PAH rats were induced by injection of monocrotaline (MCT) (40 mg/kg), followed by four weeks of treatment with CANA (30 mg/kg/day) or saline alone. Pulmonary artery and right ventricular (RV) remodeling and dysfunction in PAH were alleviated with CANA, as assessed by echocardiography. Hemodynamic parameters and structural of pulmonary arteriole, including vascular wall thickness and wall area, were reduced by CANA. RV hypertrophy index, cardiomyocyte hypertrophy, and fibrosis were decreased with CANA treatment. PASMCs proliferation was inhibited by CANA under stimulation by platelet-derived growth factor (PDGF)-BB or hypoxia. Activation of AMP kinase (AMPK) was induced by CANA treatment in cultured PASMCs in a time- and concentration-dependent manner. These effects of CANA were attenuated when treatment with compound C, an AMPK inhibitor. Abundant expression of SGLT1 was observed in PASMCs and pulmonary arteries, while SGLT2 expression was undetectable. SGLT1 increased in response to PDGF-BB or hypoxia stimulation, while PASMCs proliferation was inhibited and beneficial effects of CANA were counteracted by knockdown of SGLT1. Our research demonstrated for the first time that CANA inhibited the proliferation of PASMCs by regulating SGLT1/AMPK signaling and thus exerted an anti-proliferative effect on MCT-induced PAH.

The role and mechanism of AMPK in pulmonary hypertension

Pulmonary hypertension (PH) is a chronic progressive disease with high mortality. There has been more and more research focusing on the role of AMPK in PH. AMPK consists of three subunits-α, β, and γ. The crosstalk among these subunits ultimately leads to a delicate balance to affect PH, which results in conflicting conclusions about the role of AMPK in PH. It is still unclear how these subunits interfere with each other and achieve balance to improve or deteriorate PH. Several signaling pathways are related to AMPK in the treatment of PH, including AMPK/eNOS/NO pathway, Nox4/mTORC2/AMPK pathway, AMPK/BMP/Smad pathway, and SIRT3-AMPK pathway. Among these pathways, the role and mechanism of AMPK/eNOS/NO and Nox4/mTORC2/AMPK pathways are clearer than others, while the SIRT3-AMPK pathway remains still unclear in the treatment of PH. There are drugs targeting AMPK to improve PH, such as metformin (MET), MET combination, and rhodiola extract. In addition, several novel factors target AMPK for improving PH, such as ADAMTS8, TUFM, and Salt-inducible kinases. However, more researches are needed to explore the specific AMPK signaling pathways involved in these novel factors in the future. In conclusion, AMPK plays an important role in PH.

Current Management and Future Directions for Pulmonary Arterial Hypertension Associated with Congenital Heart Disease

Current management of patients with congenital heart disease has increased their survival into adulthood. This is accompanied by potential cardiac complications, including pulmonary hypertension associated with congenital heart disease (PAH-CHD). PAH-CHD constitutes a challenging subgroup of pulmonary hypertension and requires expert management to improve quality of life and prognosis. Novel agents have shown a significant improvement in morbidity and mortality in patients with pulmonary arterial hypertension. However, the long-term effects of these medications on PAH-CHD patients remain somewhat uncertain, necessitating treatment plans largely founded on the clinical experience of the healthcare providers. The aim of this review is to summarize the current evidence and future perspectives regarding treatment strategies for PAH-CHD to help better guide management of this complex disease.

Maternal exercise represses Nox4 via SIRT1 to prevent vascular oxidative stress and endothelial dysfunction in SHR offspring

Maternal exercise during pregnancy has emerged as a potentially promising approach to protect offspring from cardiovascular disease, including hypertension. Although endothelial dysfunction is involved in the pathophysiology of hypertension, limited studies have characterized how maternal exercise influences endothelial function of hypertensive offspring. In this study, pregnant spontaneously hypertensive rats and Wistar-Kyoto rats were assigned either to a sedentary lifestyle or to swimming training daily, and fetal histone deacetylase-mediated epigenetic modification and offspring vascular function of mesenteric arteries were analyzed. Maternal exercise ameliorated the impairment of acetylcholine-induced vasodilation without affecting sodium nitroprusside-induced vasodilation in mesenteric arteries from the hypertensive offspring. In accordance, maternal exercise reduced NADPH oxidase-4 (Nox4) protein to prevent the loss of nitric oxide generation and increased reactive oxygen species production in mesenteric arteries of hypertensive offspring. We further found that maternal exercise during pregnancy upregulated vascular SIRT1 (sirtuin 1) expression, leading to a low level of H3K9ac (histone H3 lysine 9 acetylation), resulting in the transcriptional downregulation of Nox4 in mesenteric arteries of hypertensive fetuses. These findings show that maternal exercise alleviates oxidative stress and the impairment of endothelium-dependent vasodilatation via SIRT1-regulated deacetylation of Nox4, which might contribute to improved vascular function in hypertensive offspring.