Inflammatory and lipid regulation by cholinergic activity in epicardial stromal cells from patients who underwent open-heart surgery.

The modulation of acetylcholine (ACh) release by botulinum toxin injection into epicardial fat diminishes 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, lipidic and fibroblastic profile of epicardial stroma from patients who underwent open-heart surgery, their regulation by cholinergic activity and its association with AF. We performed in vitro and ex vivo assays from paired subcutaneous and epicardial stromal cells or explants from 33 patients. Acute ACh effects in inflammation and lipid-related genes were analysed by qPCR, in intracellular calcium mobilization were performed by Fluo-4 AM staining and in neutrophil migration by trans-well assays. Chronic ACh effects on lipid accumulation were visualized by AdipoRed. Plasma protein regulation by parasympathetic denervation was studied in vagotomized rats. Our results showed a higher pro-inflammatory profile in epicardial regarding subcutaneous stromal cells. Acute ACh treatment up-regulated monocyte chemoattractant protein 1 levels. Chronic ACh treatment improved lipid accumulation within epicardial stromal cells (60.50% [22.82-85.13] vs 13.85% [6.17-23.16], P < .001). Additionally, patients with AF had higher levels of fatty acid-binding protein 4 (1.54 ± 0.01 vs 1.47 ± 0.01, P = .005). Its plasma levels were pronouncedly declined in vagotomized rats (2.02 ± 0.21 ng/mL vs 0.65 ± 0.23 ng/mL, P < .001). Our findings support the characterization of acute or chronic cholinergic activity on epicardial stroma and its association with AF.

CD5L, Macrophage Apoptosis Inhibitor, Was Identified in Epicardial Fat-Secretome and Regulated by Isoproterenol From Patients With Heart Failure.

OBJECTIVES: Neurohormonal dysfunction, which can regulate epicardial fat activity, is one of the main promoters of atrial fibrillation (AF) in patients with heart failure (HF). Our aim was to study the epicardial fat mediators for AF in patients with HF and its catecholaminergic regulation. METHODS: We have included 29 patients with HF who underwent cardiac surgery and were followed up for 5 years. Released proteins by epicardial adipose tissue (EAT) after isoproterenol treatment were identified by nano-high-performance liquid chromatography (HPLC) and triple time-of-flight (TOF) analysis. Common and differential identified proteins in groups of patients with AF before and after surgery were determined by the FunRich tool. Plasma and epicardial fat biopsy proteins were quantified by western blot. RESULTS: Our results identified 17 common released proteins by EAT, after isoproterenol treatment, from HF patients who suffered AF or developed new-onset AF during follow-up. Mostly, they were involved on inflammatory response and extracellular matrix. One of them was CD5L, a macrophage apoptosis inhibitor. Its secretion by isoproterenol treatment was validated on western blot. The CD5L levels on epicardial fat were also higher in the group of male patients who present or develop AF (0.44 ± 0.05 vs. 0.18 ± 0.15; p < 0.016). However, there were no differences regarding plasma levels. CONCLUSION: Our results suggest the role of epicardial fat CD5L as a mediator of AF and its possible paracrine effect by catecholaminergic activity.

High released lactate by epicardial fat from coronary artery disease patients is reduced by dapagliflozin treatment.

BACKGROUND AND AIMS: Dapagliflozin, a sodium-glucose co-transporter 2 inhibitor, improves glucose uptake by epicardial adipose tissue (EAT). However, its metabolism might raise the lactate production and acidosis under hypoxia conditions, i.e. coronary artery disease (CAD), or lipogenesis and, in consequence, expand adipose tissue. Since lactate secreted by adipose tissue is correlated with tissue stress and inflammation, our aim was to study glucose metabolism by epicardial fat in CAD and its regulation by dapagliflozin. METHODS: Paired EAT and subcutaneous adipose tissue (SAT) biopsies from 49 patients who underwent open-heart surgery were cultured and split into three equal pieces, some treated with and others without dapagliflozin at 10 or 100 µM for 6 h. Anaerobic glucose metabolites were measured in supernatants of fat pads, and acidosis on adipogenesis-induced primary culture cells was analysed by colorimetric or fluorescence assays. Gene expression levels were assessed by real-time polymerase chain reaction. RESULTS: Our results showed that dapagliflozin reduced the released lactate and acidosis in epicardial fat (p < 0.05) without changes in lipid storage-involved genes. In addition, this drug induced gene expression levels of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α), a mitochondrial biogenesis-involved gene in both EAT and SAT (p < 0.05). After splitting the population regarding the presence of CAD, we observed higher lactate production in EAT from these patients (2.46 [1.75-3.47] mM), which was reduced after treatment with dapagliflozin 100 µM (1.99 [1.08-2.99] mM, p < 0.01). CONCLUSIONS: Dapagliflozin improved glucose metabolism without lipogenesis-involved gene regulation or lactate production, mainly in patients with CAD. These results suggest an improvement of glucose oxidation metabolism that can contribute to cardiovascular benefits.