PhD Scientific Days 2024

Molecular Medicine III.

Reduced Circulating CD63+ Extracellular Vesicles Levels Associate with Atherogenic Pathways in Hypercholesterolaemic Mice and Humans

Text of the abstract

Introduction: The association and co-isolation of low-density lipoprotein (LDL) and extracellular vesicles (EVs) has been shown in blood plasma; however, the biological significance of this is not fully understood.
Aim: Here we aim to explore this relationship to better understand the role EVs play in atherogenesis.
Methods: Wild-type (WT), PCSK9−/−, and LDLR−/− C57BL/6 mice were used in this study. 11-week-old male mice were fed high-fat diet (HFD) for 12 weeks or kept on normal diet for 22-months.
Cardiac function was assessed by ultrasound. Circulating EVs were measured using flow cytometry.
Plaques were analysed post-mortem using Oil-Red-O staining. EVs were measured from blood plasma of normocholesterolaemic and hypercholesterolaemic clinical patients.
Results: Using annexin V and CD63 staining, we found an increase in EV levels in LDLR−/− and PCSK9−/− mice after HFD, and all mice groups showed a reduction in EV levels after HFD, where cholesterol levels were increased across the board. CD81 showed no change in any group either before HFD, after HFD, or at 22 months of age. There was no change in plaque formation after HFD, however, a significant increase was observed in LDLR−/− mice at 22-months. PCSK9−/− mice had a higher body mass at all given time points. HFD had less effect on cardiovascular health in the PCSK9−/− mice compared to WT. At age 22 months, cardiovascular function was depleted in all groups and CD63+ EV levels were depleted in kind. Similar to mice, CD63+ EVs were significantly depleted in patients with hypercholesterolaemia.
Conclusions: PCSK9−/− mice after HFD show a prognostically favourable cardiovascular function, however, these mice are also obesogenic, highlighting the importance of proper diet for PCSK9 inhibition therapeutics. Circulating EVs show an overall inverse relationship to cholesterol such that increased EVs correlate to lower risk for atherosclerotic cardiovascular disease. HFD depletes cardiac function, but atherosclerotic development is slow progressing, even in hypercholesterolaemic models.
Funding: Horizon 2020 Programme No. 739593, OTKA FK 147023, VEKOP-2.3.2-162016-00002, VEKOP-2.3.3-15-2017-00016, The Higher Education Excellence Program (FIKP) TKP2021-EGA-23, RRF-2.3.121-2022-00003 (National Cardiovascular Laboratory Program), 2019-2.1.7-ERA-NET-2021-00015 and Semmelweis 250+ Excellence PhD Scholarship.