Endocrine Abstracts

Introduction: Obesity is associated with increased cardiovascular disease (CVD) risk but the underlying pathways are unclear. Extracellular vesicles (EVs) are circulating submicron particles containing proteins, enzymes and mRNA of their donor cells. They could mediate some of these risks by paracrine actions in target cells.

Aims: To compare the concentration and characteristics of circulating EVs from healthy volunteers (HV) and morbidly overweight (MO) patients.

Methods: EVs were isolated from venous blood in HV (n=49, age 33±9 years, BMI 27±6 kg/m²) and MO (n=21, age 51.7±11 years, BMI 55±7 kg/m²) subjects by ultracentrifugation. EV concentration and size distribution was established by Nanoparticle Tracking Analysis (NTA). Time Resolved Fluorescence (TRF) immunoassay was applied to establish cellular origin and adipokine content: CD41 (platelets), CD11b (monocytes/macrophages), CD235a (erythrocytes), CD144 (endothelial cells), CD9 (exosomes), TNFα, interferon γ, Fatty Acid Binding Protein 4 (FABP4) and PPARγ.

Results: EV concentration was significantly higher in the MO cohort (13.8±3.1x10¹¹/mL of plasma vs 4.6±0.4x10¹¹/mL (P<0.0001)) but EV size distribution was similar, and predominantly in the exosomal range. CD9 and CD11b expression was not different between groups (50874 (17393-117688) vs 33222 (5536-104080); 14903 (2111-482013) vs 2756 2(404.0-112260) arbitrary TRF units (a.u.), respectively but expression of CD41, CD144 and CD235a was higher in the MO group: 22926 (10402-72078) vs 12962 (2568-34360); 12080 (3941-58123) vs 6076 (320.0-36106); 9585 (2668-24785) vs 5232 (416.0-25128) a.u., all P<0.01). EVs in MO subjects showed significantly higher expression of TNFα, interferon γ and FABP4 (27769 (15835-107710) vs 5425 (42.00-35230); 57028 (4558-157275) vs 37982(1240-103628); 38849 (11637-77248) vs 14445 (258.0-57026) a.u., all P<0.001) but no differences were seen in PPARγ expression.

Conclusions: Circulating EVs are elevated in morbidly obese subjects and are associated with enhanced platelet, endothelial and erythrocyte cell-of-origin expression. Coupled with increased expression of FABP4, TNFα and interferon γ, this suggests that EVs may, at least in part, contribute to the increased CVD morbidity observed in obesity.