Johanna Matilainen is a PhD researcher at the University of Eastern Finland, Kuopio campus. She is conducting her research in the doctoral program of molecular medicine, under the supervision of Kirsi Rilla, Ville Männistö, Petteri Nieminen and Anne-Mari Mustonen.
Johanna is also the chair of The Finnish Society for cell biology, and a board member of the Finnish Association for the Study of Obesity (FASO: https://suomenlihavuustutkijat.fi/). In her recent work, published in The Journal of Translational Medicine (available at this link: https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-024-05249-w), Johanna and her colleagues investigated the effects of obesity on extracellular vesicle secretion from human adipocytes and adipose tissue.
Extracellular vesicles (EVs) are a highly heterogenous group of nanosized membrane particles that are secreted by all mammalian cell types. EVs are present in all body fluids, and they carry all kinds of biomolecules present in the cells from which EVs are secreted. Thus, EVs are bioactive, making them important cellular communicators in normal homeostasis, but also in various diseases.
As in many conditions, recent studies have shown that the levels of circulating EVs are increased in obesity. However, mechanistic research on obesity’s impact on EV secretion from adipocytes and adipose tissue has remained scarce, and most of the previous investigations have utilized EVs from murine adipocytes and adipose tissue. Moreover, the previous research has mainly focused on protein and miRNA content of mouse adipocyte EVs, leaving fatty acid cargo of EVs highly under-examined. Thus, Matilainen and co-authors investigated the role of adipocyte and adipose tissue EVs in human obesity, utilizing human SGBS adipocyte cell line, visceral and subcutaneous adipose tissue, as well as plasma from individuals with obesity. This study also provided the first, detailed FA profiles of human adipocyte and adipose tissue EVs.
The authors observed that inflammatory components related to obesity increase EV secretion from human adipocytes, and that human visceral adipose tissue secretes more EVs than subcutaneous adipose tissue. The latter was shown to the best of the authors’ knowledge, for the first time with statistical support. Moreover, plasma EVs from people with obesity contained more adiponectin positive EVs than the ones from people with normal weight, further supporting the higher EV secretion from adipose tissue in obesity. Plasma EV counts correlated positively with BMI and TNF expression in subcutaneous adipose tissue, connecting increased EV secretion with adipose expansion and inflammation. For the first time with high-resolution confocal microscopy of EVs, the authors provided evidence that adipocyte EVs can act as carriers of excess lipids. Compared to previous studies with murine material, differing EV secretion patterns and their fatty acid profiles were also observed.
These results suggest that adipose tissue EVs act as important stress responders and lipid redistributors in human obesity. As the study opens numerous possibilities, Johanna is planning to continue as a postdoctoral researcher to further explore EV-mediated mechanisms in obesity-related conditions.
If you are interested in collaborating or finding out more about this work, please find contact details here: https://uefconnect.uef.fi/en/person/johanna.matilainen/
https://www.linkedin.com/in/johannamatilainen/
https://uefconnect.uef.fi/en/group/rilla-lab/
https://suomenlihavuustutkijat.fi/
Please find the article here: https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-024-05249-w