l-Carnitine therapy improves right heart dysfunction through Cpt1-dependent fatty acid oxidation

The therapeutic landscape of citrin deficiency

Citrin deficiency (CD) is a recessive, liver disease caused by sequence variants in the SLC25A13 gene encoding a mitochondrial aspartate-glutamate transporter. CD manifests as different age-dependent phenotypes and affects crucial hepatic metabolic pathways including malate-aspartate-shuttle, glycolysis, gluconeogenesis, de novo lipogenesis and the tricarboxylic acid and urea cycles. Although the exact pathophysiology of CD remains unclear, impaired use of glucose and fatty acids as energy sources due to NADH shuttle defects and PPARα downregulation, respectively, indicates evident energy deficit in CD hepatocytes. The present review summarizes current trends on available and potential treatments for CD. Baseline recommendation for CD patients is dietary management, often already present as a self-selected food preference, that includes protein and fat-rich food, and avoidance of excess carbohydrates. At present, liver transplantation remains the sole curative option for severe CD cases. Our extensive literature review indicated medium-chain triglycerides (MCT) as the most widely used CD treatment in all age groups. MCT can effectively improve symptoms across disease phenotypes by rapidly supplying energy to the liver, restoring redox balance and inducing lipogenesis. In contrast, sodium pyruvate restored glycolysis and displayed initial preclinical promise, with however limited efficacy in adult CD patients. Ursodeoxycholic acid, nitrogen scavengers and L-arginine treatments effectively address specific pathophysiological aspects such as cholestasis and hyperammonemia and are commonly administered in combination with other drugs. Finally, future possibilities including restoring redox balance, amino acid supplementation, enhancing bioenergetics, improving ureagenesis and mRNA/DNA-based gene therapy are also discussed.

Vitamin C deficiency can lead to pulmonary hypertension: a systematic review of case reports

BACKGROUND

In the early literature, unintentional vitamin C deficiency in humans was associated with heart failure. Experimental vitamin C deficiency in guinea pigs caused enlargement of the heart. The purpose of this study was to collect and analyze case reports on vitamin C and pulmonary hypertension.

METHODS

We searched Pubmed and Scopus for case studies in which vitamin C deficiency was considered to be the cause of pulmonary hypertension. We selected reports in which pulmonary hypertension was diagnosed by echocardiography or catheterization, for any age, sex, or dosage of vitamin C. We extracted quantitative data for our analysis. We used the mean pulmonary artery pressure (mPAP) as the outcome of primary interest.

RESULTS

We identified 32 case reports, 21 of which were published in the last 5 years. Dyspnea was reported in 69%, edema in 53% and fatigue in 28% of the patients. Vitamin C plasma levels, measured in 27 cases, were undetectable in 24 and very low in 3 cases. Diet was poor in 30 cases and 17 cases had neuropsychiatric disorders. Right ventricular enlargement was reported in 24 cases. During periods of vitamin C deficiency, the median mPAP was 48 mmHg (range 29-77 mmHg; N = 28). After the start of vitamin C administration, the median mPAP was 20 mmHg (range 12-33 mmHg; N = 18). For the latter 18 cases, mPAP was 2.4-fold (median) higher during vitamin C deficiency. Pulmonary vascular resistance (PVR) during vitamin C deficiency was reported for 9 cases, ranging from 4.1 to 41 Wood units. PVR was 9-fold (median; N = 5) higher during vitamin C deficiency than during vitamin C administration. In 8 cases, there was direct evidence that the cases were pulmonary artery hypertension (PAH). Probably the majority of the remaining cases were also PAH.

CONCLUSIONS

The cases analyzed in our study indicate that pulmonary hypertension can be one explanation for the reported heart failure of scurvy patients in the early literature. It would seem sensible to measure plasma vitamin C levels of patients with PH and examine the effects of vitamin C administration.

Role of Oxygen Starvation in Right Ventricular Decompensation and Failure in Pulmonary Arterial Hypertension

Right ventricular (RV) function and eventually failure determine outcome in patients with pulmonary arterial hypertension (PAH). Initially, RV responds to an increased load caused by PAH with adaptive hypertrophy; however, eventually RV failure ensues. Unfortunately, it is unclear what causes the transition from compensated RV hypertrophy to decompensated RV failure. Moreover, at present, there are no therapies for RV failure; those for left ventricular (LV) failure are ineffective, and no therapies specifically targeting RV are available. Thus there is a clear need for understanding the biology of RV failure and differences in physiology and pathophysiology between RV and LV that can ultimately lead to development of such therapies. In this paper, we discuss RV adaptation and maladaptation in PAH, with a particular focus of oxygen delivery and hypoxia as the principal drivers of RV hypertrophy and failure, and attempt to pinpoint potential sites for therapy.

Urolithin A protects severe acute pancreatitis-associated acute cardiac injury by regulating mitochondrial fatty acid oxidative metabolism in cardiomyocytes

Severe acute pancreatitis (SAP) often develops into acute cardiac injury (ACI), contributing to the high mortality of SAP. Urolithin A (UA; 3,8-dihydroxy-6H-dibenzopyran-6-one), a natural polyphenolic compound, has been extensively studied and shown to possess significant anti-inflammatory effects. Nevertheless, the specific effects of UA in SAP-associated acute cardiac injury (SACI) have not been definitively elucidated. Here, we investigated the therapeutic role and mechanisms of UA in SACI using transcriptomics and untargeted metabolomics analyses in a mouse model of SACI and in vitro studies. SACI resulted in severely damaged pancreatic and cardiac tissues with myocardial mitochondrial dysfunction and mitochondrial metabolism disorders. UA significantly reduced the levels of lipase, amylase and inflammatory factors, attenuated pathological damage to pancreatic and cardiac tissues, and reduced myocardial cell apoptosis and oxidative stress in SACI. Moreover, UA increased mitochondrial membrane potential and adenosine triphosphate production and restored mitochondrial metabolism, but the efficacy of UA was weakened by the inhibition of CPT1. Therefore, UA can attenuate cardiac mitochondrial dysfunction and reduce myocardial apoptosis by restoring the balance of mitochondrial fatty acid oxidation metabolism. CPT1 may be a potential target. This study has substantial implications for advancing our understanding of the pathogenesis and drug development of SACI.

Metabolomic Differences in Connective Tissue Disease-Associated Versus Idiopathic Pulmonary Arterial Hypertension in the PVDOMICS Cohort

OBJECTIVE

Patients with connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) experience worse survival and derive less benefit from pulmonary vasodilator therapies than patients with idiopathic PAH (IPAH). We sought to identify differential metabolism in patients with CTD-PAH versus patients with IPAH that might underlie these observed clinical differences.

METHODS

Adult participants with CTD-PAH (n = 141) and IPAH (n = 165) from the Pulmonary Vascular Disease Phenomics (PVDOMICS) study were included. Detailed clinical phenotyping was performed at cohort enrollment, including broad-based global metabolomic profiling of plasma samples. Participants were followed prospectively for ascertainment of outcomes. Supervised and unsupervised machine learning algorithms and regression models were used to compare CTD-PAH versus IPAH metabolomic profiles and to measure metabolite-phenotype associations and interactions. Gradients across the pulmonary circulation were assessed using paired mixed venous and wedged samples in a subset of 115 participants.

RESULTS

Metabolomic profiles distinguished CTD-PAH from IPAH, with patients with CTD-PAH demonstrating aberrant lipid metabolism with lower circulating levels of sex steroid hormones and higher free fatty acids (FAs) and FA intermediates. Acylcholines were taken up by the right ventricular-pulmonary vascular (RV-PV) circulation, particularly in CTD-PAH, while free FAs and acylcarnitines were released. In both PAH subtypes, dysregulated lipid metabolites, among others, were associated with hemodynamic and RV measurements and with transplant-free survival.

CONCLUSIONS

CTD-PAH is characterized by aberrant lipid metabolism that may signal shifted metabolic substrate utilization. Abnormalities in RV-PV FA metabolism may imply a reduced capacity for mitochondrial beta oxidation within the diseased pulmonary circulation.

Energy metabolism: A critical target of cardiovascular injury

Cardiovascular diseases are the main killers threatening human health. Many studies have shown that abnormal energy metabolism plays a key role in the occurrence and development of acute and chronic cardiovascular diseases. Regulating cardiac energy metabolism is a frontier topic in the treatment of cardiovascular diseases. However, we are not very clear about the choice of different substrates, the specific mechanism of energy metabolism participating in the course of cardiovascular disease, and how to develop appropriate drugs to regulate energy metabolism to treat cardiovascular disease. Therefore, this paper reviews how energy metabolism participates in cardiovascular pathophysiological processes and potential drugs aimed at interfering energy metabolism.It is expected to provide good suggestions for promoting the clinical prevention and treatment of cardiovascular diseases from the perspective of energy metabolism.

Mitochondrial Integrity Is Critical in Right Heart Failure Development

Molecular processes underlying right ventricular (RV) dysfunction (RVD) and right heart failure (RHF) need to be understood to develop tailored therapies for the abatement of mortality of a growing patient population. Today, the armament to combat RHF is poor, despite the advancing identification of pathomechanistic processes. Mitochondrial dysfunction implying diminished energy yield, the enhanced release of reactive oxygen species, and inefficient substrate metabolism emerges as a potentially significant cardiomyocyte subcellular protagonist in RHF development. Dependent on the course of the disease, mitochondrial biogenesis, substrate utilization, redox balance, and oxidative phosphorylation are affected. The objective of this review is to comprehensively analyze the current knowledge on mitochondrial dysregulation in preclinical and clinical RVD and RHF and to decipher the relationship between mitochondrial processes and the functional aspects of the right ventricle (RV).

Fatty Acid Metabolism in Endothelial Cell

The endothelium is a monolayer of cells lining the inner blood vessels. Endothelial cells (ECs) play indispensable roles in angiogenesis, homeostasis, and immune response under normal physiological conditions, and their dysfunction is closely associated with pathologies such as cardiovascular diseases. Abnormal EC metabolism, especially dysfunctional fatty acid (FA) metabolism, contributes to the development of many diseases including pulmonary hypertension (PH). In this review, we focus on discussing the latest advances in FA metabolism in ECs under normal and pathological conditions with an emphasis on PH. We also highlight areas of research that warrant further investigation.