Leptin Modifies the Rat Heart Performance Associated with Mitochondrial Dysfunction Independently of Its Prohypertrophic Effects

Epicardial Adipose Tissue-Derived Leptin Promotes Myocardial Injury in Metabolic Syndrome Rats Through PKC/NADPH Oxidase/ROS Pathway

Background The epicardial adipose tissue (EAT) of metabolic syndrome (MetS) is abnormally accumulated with dysfunctional secretion of adipokines, closely relating to cardiac dysfunction. The current study was designed to identify the effects of EAT-derived leptin on the myocardium of MetS rats and explore the potential molecular mechanisms. Methods and Results A MetS rat model was established in 8-week-old Wistar rats by a 12-week high-fat diet. MetS rats exhibited increased leptin secretion from EAT, cardiac hypertrophy, and diastolic dysfunction with preserved systolic function. The myocardium of MetS rats had abnormal structure, increased oxidative stress injury, and higher inflammatory factor levels, especially the subepicardial myocardium, which was correlated with the EAT-derived leptin level but not the serum leptin. The EAT was separated from each group of rats to prepare EAT-conditioned medium. H9C2 rat cardiomyoblasts were treated with EAT-conditioned medium or leptin, plus various inhibitors. EAT-derived leptin from MetS rats promoted mitochondrial oxidative stress and dysfunction, induced mitochondrial pathway apoptosis, and inhibited cell viability in H9C2 cardiomyoblasts via the protein kinase C/reduced nicotinamide adenine dinucleotide phosphate oxidase/reactive oxygen species (PKC/NADPH oxidase/ROS) pathway. EAT-derived leptin from MetS rats stimulated inflammation in H9C2 cardiomyocytes by promoting activator protein 1 nuclear translocation via the PKC/NADPH oxidase/ROS pathway. Leptin promoted the interaction between p-p47phox and gp91phox in H9C2 cardiomyocytes via protein kinase C, activating nicotinamide adenine dinucleotide phosphate oxidase, increasing reactive oxygen species generation, and inhibiting cell viability. Conclusions EAT-derived leptin induces MetS-related myocardial injury through the following 2 cooperative ways via PKC/NADPH oxidase/ROS pathway: (1) inducing mitochondrial pathway apoptosis by promoting mitochondrial oxidative stress and dysfunction; and (2) stimulating inflammation by promoting activator protein 1 nuclear translocation.

Hyperleptinemia results in systemic inflammation and the exacerbation of ischemia-reperfusion myocardial injury

Aim

Hyperleptinemia potentiates the effects of many atherogenic factors, such as inflammation, platelet aggregation, migration, hypertrophy, proliferation of vascular smooth muscle cells, and endothelial cell dysfunction. The present study analysed the effects of long-term hyperleptinemia in an in vivo myocardial ischemia-reperfusion model to demonstrate whether the in vivo deleterious effect also affects cardiac structure and function.

Main methods

Rats were subcutaneously administered leptin for 8 days to estimate the involvement of the JAK/STAT pathway. Data from 58 male Wistar rats were included in the final analysis. Myocardial infarction (MI) was modelled by the 30-minute ligation of the main left coronary artery followed by 120-minute reperfusion. Hemodynamic measurements, electrocardiography monitoring, echocardiography, myocardial infarct size and area at risk, blood biochemical parameters, leptin, IL-6, TNF-alpha, FGF-21, and cardiomyocyte morphology were measured. The expression of JAK2, p-JAK2, STAT3, p-STAT3 was assessed by Western Blot analysis. Statistical analyses were performed using IBM SPSS Statistics v.26.

Key findings

Eight-day hyperleptinemia in rats leads to an increase in blood pressure and heart rate, myocardial hypertrophy, impaired LV function, the frequency of ischemic arrhythmias, dyslipidemia, systemic inflammation, and the size of induced myocardial infarction. Significance: The blockade of the JAK/STAT signalling pathway effectively reverses the negative effects of leptin, including increased blood pressure and total cholesterol.

Leptin, Galectin-3 and Angiotensin II Type 1 Receptor Polymorphism in Overweight and Obese Patients with Heart Failure - Role and Functional Interplay

Background and Aims

Leptin, one of the best-known adipocytes, together with the renin-angiotensin-aldosterone system and galectin-3 are important players in inflammation, arterial hypertension and heart failure pathophysiology. Moreover, uninucleotide A1166C polymorphism is associated with hypertension and poor prognosis in heart failure. The aim of the study was to investigate a possible relationship between leptin serum values, specific heart failure biomarkers and the presence of AT1 receptor A1166C polymorphism in overweight and obese heart failure patients.

Methods

The study included 88 consecutive overweight and obese patients admitted for decompensated heart failure. NT-proBNP, MR-proANP, galectin-3 and leptin levels were determined on the arrival day. Genotyping of the A1166C allele – AT1 receptor gene was performed in all patients in order to find variants.

Results

We found a strong positive correlation (r = 0.347, p = 0.001) between leptin serum concentrations and BMI. Leptin levels were not correlated with heart failure biomarkers (NT-proBNP, MR-proANP and galectin-3). All homozygote CC variants were hypertensive, but we registered no significant difference in genetic AC and AA variants distribution between hypertensive and normotensive. Leptin was not significantly modified by the presence of potentially pathogenic A1166C–AT 1 receptor genotypes (AC + CC). But, galectin-3 was found in higher concentrations in patients with heterozygous and homozygous A1166C mutations.

Conclusion

Overweight and obese patients with heart failure display high leptin serum levels. Leptin does not offer incremental prognostic value in heart failure overweight and obese patients. But, galectin-3 was found in higher concentrations in patients with heterozygous and homozygous A1166C mutations, suggesting a worse prognosis probably due to more advanced cardiac fibrosis.

Leptin Levels are Associated with Subclinical Cardiac Dysfunction in Obese Adolescents

PURPOSE

The purposes of this study were to use speckle tracking echocardiography to confirm the influence of obesity on cardiac functions and to assess their relationships with leptin and uric acid levels in obese adolescents.

METHODS

Eighty-one participants aged 16-19 years were recruited and classified as either non-obese (n = 30) or obese (n = 51). Global longitudinal strain (GLS), leptin and uric acid levels for each group were assessed and compared. The data from obese participants were then compared based on their leptin levels and analyzed for correlation using regression analysis.

RESULTS

The obese group had significantly lower absolute GLS compared to the non-obese group (19.10 ± 0.30 versus 21.10 ± 0.30%, p < 0.001). In obese group, subclinical cardiac dysfunction was worse in the hyperleptinemic group than that of the normoleptinemic group (p = 0.03). Multivariate regression analysis showed that leptin and triglyceride levels were negatively associated with absolute GLS. Leptin could predict the absolute GLS with β = -0.35 (p = 0.02).

CONCLUSION

Subclinical left ventricular systolic dysfunction was found in obese adolescents, while GLS was worse in the hyperleptinemic subjects. Leptin, but not uric acid, levels were associated with a worsening of GLS.