Extracellular Vesicles: The Hidden Messengers of Adipose Tissue in Obesity

Shane

Jul 9, 20242y ago

Category

Science
Summary

Increased secretion of adipocyte-derived extracellular vesicles is associated with adipose tissue inflammation and the mobilization of excess lipid in human obesity - Journal of Translational Medicine

Background Obesity is a worldwide epidemic characterized by adipose tissue (AT) inflammation. AT is also a source of extracellular vesicles (EVs) that have recently been implicated in disorders related to metabolic syndrome. However, our understanding of mechanistic aspect of obesity’s impact on EV secretion from human AT remains limited. Methods We investigated EVs from human Simpson Golabi Behmel Syndrome (SGBS) adipocytes, and from AT as well as plasma of subjects undergoing bariatric surgery. SGBS cells were treated with TNFα, palmitic acid, and eicosapentaenoic acid. Various analyses, including nanoparticle tracking analysis, electron microscopy, high-resolution confocal microscopy, and gas chromatography–mass spectrometry, were utilized to study EVs. Plasma EVs were analyzed with imaging flow cytometry. Results EVs from mature SGBS cells differed significantly in size and quantity compared to preadipocytes, disagreeing with previous findings in mouse adipocytes and indicating that adipogenesis promotes EV secretion in human adipocytes. Inflammatory stimuli also induced EV secretion, and altered EV fatty acid (FA) profiles more than those of cells, suggesting the role of EVs as rapid responders to metabolic shifts. Visceral AT (VAT) exhibited higher EV secretion compared to subcutaneous AT (SAT), with VAT EV counts positively correlating with plasma triacylglycerol (TAG) levels. Notably, the plasma EVs of subjects with obesity contained a higher number of adiponectin-positive EVs than those of lean subjects, further demonstrating higher AT EV secretion in obesity. Moreover, plasma EV counts of people with obesity positively correlated with body mass index and TNF expression in SAT, connecting increased EV secretion with AT expansion and inflammation. Finally, EVs from SGBS adipocytes and AT contained TAGs, and EV secretion increased despite signs of less active lipolytic pathways, indicating that AT EVs could be involved in the mobilization of excess lipids into circulation. Conclusions We are the first to provide detailed FA profiles of human AT EVs. We report that AT EV secretion increases in human obesity, implicating their role in TAG transport and association with adverse metabolic parameters, thereby emphasizing their role in metabolic disorders. These findings promote our understanding of the roles that EVs play in human AT biology and metabolic disorders.

doi.org

In the complex world of obesity research, a groundbreaking study has unveiled fascinating insights into the role of extracellular vesicles (EVs) secreted by adipose tissue. This article delves into the key findings of a comprehensive research project that sheds light on how these tiny cellular messengers may hold clues to understanding and potentially treating obesity-related disorders.

The Hidden World of Extracellular Vesicles

Extracellular vesicles are minuscule membrane-bound structures released by cells, acting as crucial communication vehicles in our bodies. Recent research has revealed that adipose tissue, commonly known as fat, is a significant source of these vesicles. But what role do they play in obesity?

Visceral Fat: A Prolific EV Producer

One of the study's most striking findings is that visceral adipose tissue (VAT) - the fat surrounding our internal organs - secretes more EVs than subcutaneous adipose tissue (SAT), the fat just beneath our skin. This discovery is particularly significant because VAT is strongly associated with metabolic complications in obesity.

EVs as Lipid Transporters

In a fascinating twist, the research revealed that adipose tissue EVs contain triacylglycerols (TAGs), suggesting they may play a role in lipid transport. This finding opens up new avenues for understanding how excess fat is mobilized in the body, potentially offering new targets for obesity treatment.

Inflammation and EV Secretion

The study also uncovered a link between inflammation and increased EV secretion. When exposed to inflammatory stimuli, adipocytes (fat cells) produced more EVs. This connection provides valuable insights into the complex relationship between obesity, inflammation, and metabolic disorders.

Implications for Obesity Research and Treatment

These findings have significant implications for our understanding of obesity and related metabolic disorders. By uncovering the role of EVs in adipose tissue communication and lipid transport, researchers have opened new avenues for potential diagnostic tools and therapeutic interventions.

As we continue to unravel the mysteries of cellular communication in obesity, extracellular vesicles may prove to be a key piece of the puzzle. Their potential as biomarkers for obesity-related conditions and targets for novel treatments is an exciting prospect for future research.

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