# Diabetes Alters microRNA Expression in Epicardial and Subcutaneous Adipose Tissue from Patients Undergoing Elective Cardiac Surgery

## TL;DR

This study shows that diabetes changes microRNA levels in heart-related fat tissue, which could affect heart cell growth and function.

## Contribution

The study identifies diabetes-specific microRNA changes in epicardial fat, linking them to heart-related biological pathways.

## Key findings

- Epicardial adipose tissue has a unique microRNA profile, with 34 miRNAs uniquely expressed.
- Diabetes increases miR-155-5p in epicardial fat and miR-93-3p and miR-223-3p in subcutaneous fat.
- EAT miRNAs target genes involved in heart cell growth and differentiation.

## Abstract

What are the main findings

A microRNA discovery panel identified 34 microRNAs to be uniquely
expressed in epicardial adipose tissue (EAT).

Diabetes increases the expression of miR-155-5p in EAT and of
miR-93-3p and miR-223-3p in subcutaneous AT.

What are the implications of the main findings?

EAT microRNA targets are enriched in pathways for heart cell
growth and differentiation.

Epicardial adipose tissue (EAT) function may influence the heart, given its metabolic actions and proximity to the heart. We hypothesized that diabetes mellitus (DM) alters miRNA expression across adipose tissue types, and that modifications in EAT may have critical implications for cardiac physiology. To test this, we compared EAT and subcutaneous adipose tissue (SAT) miRNA profiles between patients with and without DM and across tissues within each disease group. Paired biopsies from patients with (n = 18) and without DM (n = 46) undergoing cardiac surgery were analyzed using miRNA profiling and bioinformatics. Among 680 miRNAs screened, 34 were uniquely expressed in EAT, confirming a distinct molecular signature in this fat depot. Notably, miR-155-5p was significantly elevated in EAT from patients with DM, indicating a localized metabolic effect. In SAT, miR-93-3p and miR-223-3p were upregulated in patients with DM and consistently higher than in EAT, regardless of DM status, indicating tissue-specific regulation. miR-324-5p was more expressed in SAT of patients in the NDM group, reflecting combined effects of tissue type and DM. These patterns remained consistent across cardiac disease stratifications. Pathway analysis revealed that miRNAs enriched in EAT target genes involved in cardiomyocyte growth and differentiation. Overall, the findings highlight the unique miRNA profile of epicardial fat and its altered response to DM, supporting its relevance in cardiac physiology.