Elevated release of extracellular vesicles in obese patients with no-alcoholic fatty liver disease (NAFLD)

Introduction: Obesity is excessive fat accumulation in adipose tissue and its prevalence has increased dramatically worldwide. Non-alcoholic liver disease (NAFLD) represents the liver manifestation of the metabolic syndrome and is closely associated to obesity. Prevalence rates of NAFLD increase in parallel to the obesity pandemic. Extracellular vesicles (EV) are recently identified membrane-encased vesicles that are secreted from cells. Our study aimed to analyze the effect of bariatric surgery on liver-related EV release and to identify markers contained in liver-specific EV.

Methods: Sera were collected from severely obese patients with NAFLD (n = 23) before and after bariatric surgery and form normal weight subjects (n = 12). EV isolation was performed from frozen serum samples by ultracentrifugation followed by PEG precipitation and EV quantification using NTA system.

Results: The number of EV in obese patients was significantly higher than in normal weight subjects (p < 0.0001). Over a period of 6 weeks after bariatric surgery a slight increase in EV numbers was observed (n.s.). Total protein content of EV increased after bariatric surgery compared to before surgery. Furthermore, the number of EV and BMI were positively correlated.

Conclusion: Increased EV release occurred in obese patients with NAFLD. Bariatric surgery led to slight increases of EV numbers and protein content, possibly suggesting a change of EV composition. In depth analysis of biological background and characterization of EV by surface proteins and content is warranted.