# Expression of Serum and Exosomal microRNA-34a in Subjects with Increased Fat Mass

## TL;DR

This study explores how microRNA-34a in blood and exosomes relates to body fat and metabolic health, suggesting it could be a non-invasive biomarker for fat-related dysfunction.

## Contribution

The study identifies miR-34a as a potential non-invasive biomarker for adipose tissue dysfunction linked to increased fat mass.

## Key findings

- miR-34a expression in serum and exosomes correlates with various metabolic and inflammatory markers.
- Serum miR-34a levels are higher than in exosomes, indicating a potential role in metabolic dysfunction and insulin resistance.
- Correlation patterns of miR-34a differ between serum and exosomes for certain lipid and glucose markers.

## Abstract

Extracellular vesicles (EVs), particularly exosomes, are key mediators of intercellular communication, transporting biomolecules such as nucleic acids, lipids, and proteins that influence immune and metabolic pathways. In adipose tissue (AT), adipocyte-derived EVs (AdEVs) play a crucial role in maintaining metabolic homeostasis and have been implicated in obesity-related dysfunction. Among their bioactive cargo, microRNAs regulate post-transcriptional gene expression and participate in immunometabolic regulation. This study aimed to determine whether miR-34a expression in serum and circulating EVs varies according to body fat percentage, to explore its potential utility as a non-invasive biomarker of AT dysfunction. A total of 142 adults (mean age 36 ± 11 years) were classified by body fat percentage (≥25% in men, ≥35% in women). Exosomes were isolated (Invitrogen®) and characterized by cryo-TEM, and miR-34a expression was quantified by qRT-PCR. miR-34a expression correlated negatively with Total Cholesterol, Triglycerides, LDLc/HDLc, TG/HDLc, BMI, C3, CRP, fasting insulin, HOMA-IR, HOMA-B, Body adiposity, Chemerin, CCL2, AdipoQT, and AdipoQ-H, but positively with HDLc and QUICKI. Notably, LDLc, sdLDLc, sdLDLc/LDLc, TC/HDLc, and fasting glucose showed opposite correlation patterns between serum and exosomes. Overall, serum miR-34a levels were higher than in exosomes, suggesting its potential as a biomarker of metabolic dysfunction and insulin resistance.