Epicardial adipose tissue deposition in patients with diabetes and renal impairment: Analysis of the literature

Identification of key genes and mechanisms of epicardial adipose tissue in patients with diabetes through bioinformatic analysis

Background

In recent years, peri-organ fat has emerged as a diagnostic and therapeutic target in metabolic diseases, including diabetes mellitus. Here, we performed a comprehensive analysis of epicardial adipose tissue (EAT) transcriptome expression differences between diabetic and non-diabetic participants and explored the possible mechanisms using various bioinformatic tools.

Methods

RNA-seq datasets GSE108971 and GSE179455 for EAT between diabetic and non-diabetic patients were obtained from the public functional genomics database Gene Expression Omnibus (GEO). The differentially expressed genes (DEGs) were identified using the R package DESeq2, then Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were analyzed. Next, a PPI (protein–protein interaction) network was constructed, and hub genes were mined using STRING and Cytoscape. Additionally, CIBERSORT was used to analyze the immune cell infiltration, and key transcription factors were predicted based on ChEA3.

Results

By comparing EAT samples between diabetic and non-diabetic patients, a total of 238 DEGs were identified, including 161 upregulated genes and 77 downregulated genes. A total of 10 genes (IL-1β, CD274, PDCD1, ITGAX, PRDM1, LAG3, TNFRSF18, CCL20, IL1RN, and SPP1) were selected as hub genes. GO and KEGG analysis showed that DEGs were mainly enriched in the inflammatory response and cytokine activity. Immune cell infiltration analysis indicated that macrophage M2 and T cells CD4 memory resting accounted for the largest proportion of these immune cells. CSRNP1, RELB, NFKB2, SNAI1, and FOSB were detected as potential transcription factors.

Conclusion

Comprehensive bioinformatic analysis was used to compare the difference in EAT between diabetic and non-diabetic patients. Several hub genes, transcription factors, and immune cell infiltration were identified. Diabetic EAT is significantly different in the inflammatory response and cytokine activity. These findings may provide new targets for the diagnosis and treatment of diabetes, as well as reduce potential cardiovascular complications in diabetic patients through EAT modification.

The Role of Epicardial Adipose Tissue in the Development of Atrial Fibrillation, Coronary Artery Disease and Chronic Heart Failure in the Context of Obesity and Type 2 Diabetes Mellitus: A Narrative Review

Cardiovascular diseases (CVDs) are a significant burden globally and are especially prevalent in obese and/or diabetic populations. Epicardial adipose tissue (EAT) surrounding the heart has been implicated in the development of CVDs as EAT can shift from a protective to a maladaptive phenotype in diseased states. In diabetic and obese patients, an elevated EAT mass both secretes pro-fibrotic/pro-inflammatory adipokines and forms intramyocardial fibrofatty infiltrates. This narrative review considers the proposed pathophysiological roles of EAT in CVDs. Diabetes is associated with a disordered energy utilization in the heart, which promotes intramyocardial fat and structural remodeling. Fibrofatty infiltrates are associated with abnormal cardiomyocyte calcium handling and repolarization, increasing the probability of afterdepolarizations. The inflammatory phenotype also promotes lateralization of connexin (Cx) proteins, undermining unidirectional conduction. These changes are associated with conduction heterogeneity, together creating a substrate for atrial fibrillation (AF). EAT is also strongly implicated in coronary artery disease (CAD); inflammatory adipokines from peri-vascular fat can modulate intra-luminal homeostasis through an “outside-to-inside” mechanism. EAT is also a significant source of sympathetic neurotransmitters, which promote progressive diastolic dysfunction with eventual cardiac failure. Further investigations on the behavior of EAT in diabetic/obese patients with CVD could help elucidate the pathogenesis and uncover potential therapeutic targets.

Metabolic, inflammatory and imaging biomarkers in evaluation of coronary atherosclerosis severity in patients with coronary artery disease and diabetes mellitus type 2

Aim. To study interconnections between epicardial adipose tissue thickness (EATt), parameters of glucose metabolism/insulin, C-reactive protein (hsCRP), serum adipokines and severity of coronary artery disease (CAD) depending on the presence of diabetes mellitus type 2 (DM 2); to determine significant markers of CAD severity in patients with DM 2. Materials and methods. The study involved 106 patients with CAD (m/f 64/42, 60.96.8 years), including patients with DM 2 (group 1, n=35) and non-diabetic patients (group 2, n=71). Severity of CAD was evaluated according to angiography data with calculation of Gensini Score (GS). EATt was assessed via echocardiography. Serum levels of glucose/insulin metabolism parameters, lipid fractions, hsCRP and adipokines were evaluated. Clinical parameters, including GS, did not differ between groups. Results. EAT thickness median was elevated in gr.1 (5.1 mm vs. 4.4 mm in group 2), while adiponectin levels were decreased (6.55 g/ml vs. 7.71 g/ml). Linear regression of body mass index and resistin levels on EATt was revealed in gr.1; in gr.2 EATt linearly increased with waist circumference increment when EATt6 mm. Linear regression of EATt on GS was revealed in gr.1 when EATt8 mm, while linear regression in the whole GS range was obtained for HDL-C and hsCRP levels. Conclusion. Study results demonstrate differences in mechanisms of deposition and functioning of epicardial and abdominal adipose tissue depending on the presence or absence of diabetic status. Patients with DM2 are characterized by the excessive EAT deposition and decrease of serum adiponectin levels compared to non-diabetic patients in the equal conditions. Independent markers of CAD severity in DM 2 are decreased HDL-C and increased hsCRP levels, but not EATt.