PhD Scientific Days 2021

MO_III_L: Molecular Sciences III. Lectures

Hepatic extracellular vesicle release and uptake under normolipemia and hyperlipidemia

Text of the abstract

Introduction
Liver has a key role in removal of extracellular vesicles (EVs) from the blood circulation, and it also significantly contributes to EV secretion. However, the knowledge regarding to the involvement of the different liver cell types is scarce.
Aims
Here we examined the different contribution of liver cell types in the dynamics of EV uptake and release both in normo- and hyperlipidemia.
Method
Plasma EV profiles of C57BL/6 mice were analyzed after 20-30 weeks on high fat diet. Furthermore, control mice were injected intravenously with 99mTc-duramycin labelled medium (~ 330 nm) and small EVs (~ 130 nm), and an hour later, biodistribution of EVs were determined by SPECT/CT. In vitro, different liver cell types were tested for EV production and uptake with/without prior oleic acid/palmitic acid treatment.
Results
Based on the EV marker expression, we found a significantly higher plasma small EV concentration after 30 weeks on high fat diet. To elucidate the involvement of primary hepatocytes, we carried out in vitro experiments. We report, that hyperlipidemic conditions significantly increased the release of medium EVs and small EVs. When investigating EV biodistribution, upon injection of 99mTc-duramycin labelled medium EVs and small EVs intravenously to mice, we detected their accumulation primarily in the liver. In vitro, we found that medium EVs were primarily taken up by Kupffer cells, while small EV uptake was the highest in liver sinusoidal endothelial cells. Finally, we demonstrated that in hyperlipidemia, there was a decreased EV uptake both by Kupffer cells and liver sinusoidal endothelial cells.
Conclusion
Our data suggest that hyperlipidema increases the release and reduces the uptake of EVs by liver cells. We also provide evidence for size-dependent differential EV uptake by the different cell types of the liver.
Funding
NVKP16-1-2016-0017, ÚNKP19-4-SE-09, János Bolyai Research Scholarship, Hungarian Scientific Research Fund (K120237), VEKOP2.3.2-16-2017-000002, VEKOP2.3.3-15-2017-00016, H2020-MSCA-ITN-2017-722148 TRAIN EV, FIKP-Therapeutic Thematic Programme, Horizon 2020 Research and Innovation Programme (739593)

University and Doctoral School

Semmelweis University, Doctoral School of Molecular Medicine