Genesis of epicardial adipocytes and its association with progenitor markers, muscarinic receptor type 3 and b-blockers intake in patients with cardiovascular disease

Introduction

Epicardial fat thickness or volume was found to be associated with cardiovascular disease (CVD). Our aim was to study the epicardial adipocyte-progenitors' markers and its association with cholinergic or adrenergic activity in patients with cardiovascular disease.

Materials and methods

We have included epicardial adipose tissue (EAT) biopsies from 29 patients underwent open-heart surgery. From 10 patients (69±5 years old, 31±8 kg/ m2, 40% CAD, 40% HF, 60% AF, 0% T2DM) stromal cells from epicardial and subcutaneous fat were isolated after collagenase activity and cultured for 14 days and then submitted to adipogenesis for next 14 days. Samples from 19 patients (60±9 years old, 29±4 kg/m2, 42% CAD, 37% HF, 32% AF, 32% T2DM, 53% β-blockers) were used for “ex vivo assays”. Explants were split into equal pieces (100 mg), treated with or without acetylcholine (ACh) for 30 min. Afterwards RNA was isolated and cDNA was amplified by real time PCR. We selected adipocytes progenitors (CD36, PREF1, COL1A1), adipocytes markers (ADIPO, FABP4), muscarinic (muscarinic receptor type 2 (CHRM2) and 3 (CHRM2)) and β-adrenergic receptors (ABRD1, ABRD2 and ABRD3). Gene expression was represented regarding ACTB as 2HK/GEN.

Results

The stromal vascular cells (SVC) from subcutaneous fat (SAT) had higher expression levels of CD36, PREF1 and COL1A1 than SVC from epicardial fat (EAT). It explains the higher adipocytes markers after adipogenesis induction in SAT than EAT cells. However, an upregulation of fibroblasts markers was detected on EAT. The levels of CD36 and PREF1 in SVC were associated with higher adipogenesis. Although CHRM2 was higher in EAT than SAT SVC, the adipogenesis induction upregulated only CHRM3 (1.48±0.065 vs 1.42±0.036 a.u.) in EAT cells. Thus, this receptor was associated with adipocytes markers in epicardial fat (r=0.777 for CD36 and r=0.746 for FABP4) and incremented in epicardial fat biopsies from patients who were taken β-blockers (1.61±0.011 n=10 vs 1.54±0.097 a.u. n=9; p=0.05) and modulated by ACh treatment (p=0.05).

Conclusions

Our results showed that CD36 and PREF1 in epicardial SVC are adipocytes progenitors. The higher presence of adipocytes markers is associated with higher levels of muscarinic receptor (CHRM3), which are upregulated in epicardial fat from patients who were taken β-blockers and modulated by cholinergic activity. Because a metabolic and lipolytic dysfunction was associated with CHRM3, the sympathetic modulation might play a role in the epicardial adipocytes genesis. Further studies are needed to understand if this mechanism might improve or not future cardiovascular events.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): ISCIII (PFIS2020)

Sex-related differences of fatty acid-binding protein 4 and leptin levels in atrial fibrillation

AIMS

Adiposity plays a key role in the pathogenesis of atrial fibrillation (AF). Our aim was to study the sex differences in adipokines levels according to AF burden.

METHODS AND RESULTS

Two independent cohorts of patients were studied: (i) consecutive patients with AF undergoing catheter ablation (n = 217) and (ii) a control group (n = 105). (i) Adipokines, oxidative stress, indirect autonomic markers, and leucocytes mRNA levels were analysed; (ii) correlation between biomarkers was explored with heatmaps and Kendall correlation coefficients; and (iii) logistic regression and random forest model were used to determine predictors of AF recurrence after ablation. Our results showed that: (i) fatty acid-binding protein 4 (FABP4) and leptin levels were higher in women than in men in both cohorts (P < 0.01). In women, FABP4 levels were higher on AF cohort (20 ± 14 control, 29 ± 18 paroxysmal AF and 31 ± 17 ng/mL persistent AF; P < 0.01). In men, leptin levels were lower on AF cohort (22 ± 15 control, 13 ± 16 paroxysmal AF and 13 ± 11 ng/mL persistent AF; P < 0.01). (ii) In female with paroxysmal AF, there was a lower acetylcholinesterase and higher carbonic anhydrase levels with respect to men (P < 0.05). (iii) Adipokines have an important role on discriminate AF recurrence after ablation. In persistent AF, FABP4 was the best predictor of recurrence after ablation (1.067, 95% confidence interval 1-1.14; P = 0.046).

CONCLUSION

The major finding of the present study is the sex-based differences of FABP4 and leptin levels according to AF burden. These adipokines are associated with oxidative stress, inflammatory and autonomic indirect markers, indicating that they may play a role in AF perpetuation.

Acute and chronic cholinergic activity in the inflammatory and lipid regulation of epicardial stromal cells from patients with and without atrial fibrillation

Aims

Acetylcholine (ACh) released modulation by botulinum toxin injection into epicardial fat diminish atrial fibrillation (AF) recurrence. These results suggest an interaction between autonomic imbalance and epicardial fat as risk factors of AF. Our aim was to study the inflammatory and lipid profile of epicardial stroma from AF patients and their regulation by high cholinergic activity.

Methods and results

We performed in vitro assays with primary cultures from paired subcutaneous and epicardial stromal cells from 33 patients. We analysed ACh effect on gene expression, intracellular calcium mobilization and neutrophil migration. Plasma protein regulation by parasympathetic denervation was performed in vagotomised rats. Acute ACh treatment up-regulated MCP1 levels on epicardial stromal cells and suggested a neutrophil infiltration enhancement. Patients with AF had a greater FABP4 gene expression (1.54±0.01 vs 1.47±0.01, p=0.005). Its plasma levels were pronouncedly declined on vagotomised rats (2.02±0.21 ng/mL vs 0.65±0.23 ng/mL, p&lt;0.001). Additionally, chronic ACh treatment improved lipid accumulation within epicardial stromal cells (60.50% [22.82–85.13] vs 13.85% [6.17–23.16], p&lt;0.001).

Conclusions

Acute ACh activity up-regulates MCP1 and calcium mobilization on epicardial stromal cells. Longer ACh treatment enhanced lipid accumulation. In this line, epicardial stroma from patients with permanent AF contains higher FABP4 expression levels. Thus, modulate cholinergic activity might reduce FABP4 since vagus nerve denervation is associated with a sharply decrease in FABP4 plasma levels.

FABP4 in human AF and vagotomised rats

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Carlos III Health Institute; Health Research Institute of Santiago de Compostela

Gender-dependent regulation of FABP4 and leptin according to atrial fibrillation burden

Aims

Adiposity plays a key role in the pathogenesis of atrial fibrillation (AF). Its associated proteins are differentially released between male and female. FABP4 and leptin are mediators in adipose tissue-inflammatory effects. Our aim was to study their gender differential behavior on mechanisms associated with AF progression.

Methods and results

Two independent cohorts were analyzed: A) patients referred for AF catheter ablation (n=217) and patients with suspected coronary artery disease referred for a CT scan (without previous history of AF) (n=105). Protein levels were determined by multiplex fluorometric immunoassay. Gene mRNA expression was analyzed by real time polymerase chain reaction. Correlation between biomarkers was explored with heatmaps and Kendall correlation coefficients. Logistic regression and random forest model determined the best predictors of AF recurrence after catheter ablation. Our results showed: 1) a distinctive profile according to gender, with an increment of FABP4 levels in women (20±14, 29±18 and 31±17 ng/mL; p=0.007) and a decrease of leptin levels in men (22±15, 13±16 and 13±11 ng/mL; p=0.001) among control, paroxysmal and persistent AF groups, respectively; 2) sex differences regarding inflammatory profile, oxidative stress and autonomic indirect markers in AF; 3) a prominent role of adipokines to discriminate AF recurrence after ablation. In persistent AF, FABP4 was the best predictor (LR coefficient 1.067, 95% CI 1–1.14, p=0.046).

Conclusion

The major finding of the present study is the sex differences of FABP4 and leptin according to AF burden. The relationship of these adipokines with oxidative stress, inflammatory and autonomic indirect markers might explain part of the mechanisms underlying the AF perpetuation.

Adipokines regarding Gender & AF burden

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Institute of Health Carlos III

Obesity-Related Genetic Determinants of Heart Failure Prognosis

PURPOSE

Recent advances in genomics offer a smart option for predicting future risk of disease and prognosis. The objective of this study was to examine the prognostic value in heart failure (HF) patients, of a series of single nucleotide polymorphisms (SNPs).

METHODS

A selection of 192 SNPs found to be related with obesity, body mass index, circulating lipids or cardiovascular diseases were genotyped in 191 patients with HF. Anthropometrical and clinical variables were collected for each patient, and death and readmission by HF were registered as the primary endpoint.

RESULTS

A total of 53 events were registered during a follow-up period of 438 (263-1077) days (median (IQR)). Eight SNPs strongly related to obesity and HF prognosis were selected as possible prognostic variables. From these, rs10189761 and rs737337 variants were independently associated with HF prognosis (HR 2.295 (1.287-4.089, 95% CI); p = 0.005), whereas rs10423928, rs1800437, rs737337 and rs9351814 were related with bad prognosis only in obese patients (HR 2.142 (1.438-3.192, 95% CI); p = 0.00018). Combined scores of the genomic variants were highly predictive of poor prognosis.

CONCLUSIONS

SNPs rs10189761 and rs737337 were identified, for the first time, as independent predictors of major clinical outcomes in patients with HF. The data suggests an additive predictive value of these SNPs for a HF prognosis. In particular for obese patients, SNPs rs10423928, rs1800437, rs737337 and rs9351814 were related with a bad prognosis. Combined scores weighting the risk of each genomic variant could effect interesting new tools to stratify the prognostic risk of HF patients.

P3494Dapagliflozin reduced lactate release by epicardial adipose tissue from CAD patients: switch from fatty acids to glucose aerobic oxidation

Background

Dapagliflozin, a sodium-glucose co-transporter 2 inhibitor, improves the glucose uptake by epicardial adipose tissue (EAT). However, its metabolic pathways are still unknown. Our aim was to clarify the EAT glucose-lipid metabolism from patients with and without coronary artery disease (CAD).

Methods

Paired subcutaneous (SAT) and EAT biopsies from 49 patients undergoing heart surgery were cultured and treated with or without dapa at 10 or 100 μM for 6 hours. Glucose, lactate and oxygen were analyzed on supernatants by colorimetric or fluorescence assays. Glycolytic, lipolytic, glyceroneogenic and lipogenic genes or protein expression levels were determined on fat tissues by RT-qPCR or western blot, respectively.

Results

Glyceroneogenic and lipid metabolism-involved genes were higher expressed in SAT than in EAT. Dapa reduced their expression in SAT but not in EAT. Lipid-droplet protein levels, perilipin (PLN A) and hormone-sensitive lipase (HSL), were reduced in EAT. Mitochondrial biogenesis-related gene PGC1α was upregulated (p<0.05). Despite this drug improved glucose utilization, it reduced lactate release and oxygen consumption in both fat pads. After classifying patients according presence/absence of CAD, we observed a greater release of lactate by EAT in patients with CAD (3.22±2.40 mM) that was remarkably reduced after dapagliflozin treatment at 10 μM (2.17±1.53 mM, p<0.01) and 100 μM (2.45±2.11 mM, p<0.001).

Clinical characteristics regarding CAD presence (n=49) Non CAD patients (n=26) CAD patients (n=23) p value Gender (male) (n/%) 14/54 20/87 0.010* Age (years) 73±9 67±12 0.026* BMI (kg/m2) 29.±4 30±4 0.377 HTA (n/%) 21/80.8 17/73.9 0.578 T2DM (n/%) 12/46 9/39 0.629 HF (n/%) 2/8 6/26 0.096 L-Lactate (mM) 2±1.1 3.2±2.4 0.029* Glucose (mg/dL) 65±15 62±22 0.539 Oxygen (RFU) 47±9 46±14 0.899 CAD: Coronary artery disease, BMI: Body mass index, HTA: arterial hypertension, T2DM: Diabetes mellitus type 2, HF: Heart failure, RFU: relative fluorescence units.

Lactate in CAD

Conclusions

Dapagliflozin reduced the anaerobic glycolytic pathway, lowering the released lactate by EAT, overall in patients with CAD. This effect suggests a protective metabolic role since high lactate was found to be a marker of poor outcomes in HF patients.

Acknowledgement/Funding

Astrazeneca

Receptor for advanced glycation end-products expression in subcutaneous adipose tissue is related to coronary artery disease

OBJECTIVE

Obesity, a risk factor for coronary artery disease (CAD), is associated with inflammation and reactive oxygen species (ROS) production, while advanced glycation end-products, through their receptor (AGER or RAGE), play an important role on these processes. The aim of this study was to analyze the expression levels of RAGE, NADPH oxidase subunits, and catalase in adipose tissue in relation with CAD.

DESIGN AND METHODS

Patients undergoing heart surgery were included in two groups: with and without CAD. Epicardial adipose tissue (EAT) and subcutaneous adipose tissue (SAT) biopsies were analyzed for gene expression by RT-quantitative PCR, immunohistochemistry, or western blot.

RESULTS

RAGE mRNA and protein expression in SAT from patients with CAD was lower than in patients without CAD. However, there was no change in EAT from patients with or without CAD. P22-PHOX and RAGE gene expression were higher in EAT than in SAT, whereas catalase mRNA levels were lower. NADPH oxidase subunits and catalase mRNA expression were not influenced by CAD. Whereas NADPH oxidase-dependent oxidative response of SAT and EAT to lipid circulating levels could be different; glycemic levels were not related with the analyzed genes expression.

CONCLUSIONS

This study demonstrates that RAGE expression in SAT, but not in EAT, is down-regulated in patients with CAD with respect to those without CAD. Although changes were not observed for NADPH oxidase subunits or catalase expression between CAD and non-CAD patients, a possible relationship between ROS production and RAGE expression in adipose tissues cannot be ruled out.

Alterations in contractile protein composition and function in human atrial dilatation and atrial fibrillation

The cellular mechanisms responsible for contractile dysfunction associated with atrial fibrillation (AF) are still poorly understood. Atrial fibrillation is often preceded by atrial dilatation. This study aimed to explain contractile alterations associated with AF and their relation to atrial dilatation, by studying the relationships between atrial dimensions, contractile protein composition, force production and Ca(2+)-sensitivity. Force development was determined in mechanically isolated single skinned cardiomyocytes from right atrial appendages from patients with sinus rhythm without (SR;n=9), or with atrial dilation (SR+AD;n=11) or atrial fibrillation (AF;n=16). Echocardiography showed that, compared to the SR group, mean right atrial dimensions were increased by 18% and 35% in the SR+AD and AF group, respectively (P<0.05). Protein composition was determined by 1- and 2-dimensional gel electrophoresis. Compared to the SR group, the AF group exhibited: a reduction in the kinetics of force redevelopment (K(tr)) in isolated atrial cardiomyocytes, enhanced protein expression of the slow myosin heavy chain isoform (beta-MHC), an increase in troponin T (TnT) phosphorylation and a marked increase (70%) of the cytoskeletal protein desmin. Significant correlations were observed between the right atrial major axis (RA(major)) and beta-MHC expression as well as the desmin/actin ratio. Our findings indicate that dilatation may influence cardiomyocyte stability through altered desmin expression, but that it does not predispose to the alterations in contractile function observed in AF.

No direct effect of creatine phosphate on the cross-bridge cycle in cardiac myofibrils

Creatine phosphate (CP) and creatine kinase (CK) are involved in the rapid resynthesis of ATP and thereby serve to stabilize ATP concentration and to maintain free ADP low inside cardiac muscle cells during contraction. Recently, it has been suggested from experiments in permeabilized multicellular preparations that CP/CK also regulate the kinetics of the actomyosin interaction (cross-bridge cycle) and may explain contractile dysfunction, for instance, during ischemia. However, the reported effects of CP/CK may be confounded by diffusion limitations in multicellular preparations in which inorganic phosphate (P(i)) and ADP may significantly accumulate during contraction. To test this hypothesis, we measured force production and the rates of force development (k (ACT) and k (TR)) in isolated cardiac myofibrils, in which rapid concentration changes of Ca(2+), CP/CK, and P(i) were imposed using a rapid perfusion change system. The results showed that CP/CK did not influence maximum force-generating capacity, whereas P(i) markedly reduced force and increased the rates of force development. No effects of CP/CK on the rates of force development were observed, consistent with the notion that CP/CK do not exert a direct effect on the actomyosin interaction.

Myosin heavy chain composition and the economy of contraction in healthy and diseased human myocardium

Changes in myosin heavy chain (MHC) isoform expression and protein composition occur during cardiac disease and it has been suggested that even a minor shift in MHC composition may exert a considerable effect on myocardial energetics and performance. Here an overview is provided of the cellular basis of the energy utilisation in cardiac tissue and novel data are presented concerning the economy of myocardial contraction in diseased atrial and ventricular human myocardium. ATP utilisation and force development were measured at various Ca(2+) concentrations during isometric contraction in chemically skinned atrial trabeculae from patients in sinus rhythm (SR) or with chronic atrial fibrillation (AF) and in ventricular muscle strips from non-failing donor or end-stage failing hearts. Contractile protein composition was analysed by one-dimensional gel electrophoresis. Atrial fibrillation was accompanied by a significant shift from the fast alpha-MHC isoform to the slow beta-MHC isoform, whereas both donor and failing ventricular tissue contained almost exclusively the beta-MHC isoform. Simultaneous measurements of force and ATP utilisation indicated that economy of contraction is preserved in atrial fibrillation and in end-stage human heart failure.

Leptin promotes the tyrosine phosphorylation of SHC proteins and SHC association with GRB2

The identification and characterization of proteins that become tyrosine phosphorylated in response to growth factor stimulation is critical for furthering our understanding of the signal transduction pathways involved in the regulation of cell proliferation, differentiation as well as metabolic activities. In this report, we demonstrate for the first time, that leptin is able to induce the tyrosine phosphorylation of the SH(2) containing protein SHC. These studies have been carried out on a human embryonic cell line (HEK 293) transfected with the cDNA encoding for the long form of the leptin receptor and stably expressing the receptor itself. We also shown that upon tyrosine phosphorylation, SHC associated with the adaptor protein, Grb(2). The formation of this complex may directly link tyrosine phosphorylation events to Ras activation and may be a critical step in proliferation and/or differentiation of cells. In conclusion, these results indicate that leptin receptor, after binding the ligand, activates several pathways for signal transduction that might lead to mitogenic effect.

Elevated serum leptin concentrations induced by experimental acute inflammation

Leptin is a pleiotropic hormone that regulates body weight and energy expenditure. Recent findings suggest that leptin may be involved in acute and/or chronic inflammation, however only limited results are available describing the effects of in vivo models of acute inflammation on leptin secretion. The aim of this study was to evaluate serum leptin levels in response to two well-established models of acute inflammation in rats: carrageenan rat paw induced oedema and carrageenan induced pleurisy. Our results clearly show that leptin levels rise in rats in which both oedema and pleurisy were induced. Serum leptin levels in carrageenan induced paw oedema were 3.86+/-0.16 microg/L in comparison to 1.83+/-0.17 microg/L of control animals (p<0.001). A similar result was observed in carrageenan induced pleurisy animals in which leptin levels were 4.87+/-0.27 microg/L in comparison to 2.19+/-0.16 microg/L of control animals (p<0.001). The increase in leptin levels induced following carrageenan-induced pleurisy appears to be dependent on adrenal function and it is markedly blunted in adrenalectomized rats. Leptin levels in carrageenan induced pleurisy, carried out on adrenalectomized rats, were lower than intact inflamed animals, suggesting a possible involvement of endogenous glucocorticoids. In summary the results here presented show that: a) an elevated plasma leptin concentration was induced during experimental models of inflammation b) this increase is mediated to a large extent by glucocorticoids. In conclusion, acute experimental models of inflammation are associated with changes in circulating leptin suggesting a possible involvement of this hormone in the anorexia/cachexia that is frequently associated with inflammatory processes. Furthermore, our data indicate the existence of a feedback loop among glucocorticoids and leptin which might contribute to the immune response to lace the inflammatory process.