Highlights
- •Extracellular vesicles (EVs) from inflammed adipocytes increase VCAM expression in vascular endothelial cells.
- •EVs from inflammed and hypoxic adipocytes increase leukocyte attachment to vascular endothelial cells.
- •Inflammation and hypoxia affect the expression of adipokines in adipocytes and EVs.
- •Inflammation and hypoxia affect adipocyte EV yield and size.
Abstract
Background and aims
Obesity is associated with an increased risk of cardiovascular disease, but the mechanisms
involved are not completely understood. In obesity, the adipocyte microenvironment
is characterised by both hypoxia and inflammation. Therefore, we sought to determine
whether extracellular vesicles (EVs) derived from adipocytes in this setting might
be involved in mediating cardiovascular disease, specifically by promoting leukocyte
attachment to vascular endothelial cells.
Methods
Mature 3T3-L1 adipocytes were incubated for 24 h under control, TNF-α (30 ng/mL),
hypoxia (1% O2), or TNF-α+hypoxia (30 ng/mL, 1% O2) conditions. EVs were isolated by differential ultracentrifugation and analysed by
nanoparticle tracking analysis. Primary human umbilical vein endothelial cells (HUVECs)
were treated with EVs for 6 h before being lysed for Western blotting to investigate
changes in adhesion molecule production, or for use in leukocyte attachment assays.
Results
EVs from adipocytes treated with TNF-α and TNF-α+hypoxia increased vascular cell adhesion
molecule (VCAM-1) production in HUVECs compared to basal level (4.2 ± 0.6 and 3.8 ± 0.3-fold
increase, respectively (p < 0.05)), an effect that was inhibited by an anti-TNF-α neutralising antibody. Production
of other adhesion molecules (E-selectin, P-selectin, platelet endothelial cell adhesion
molecule and VE-Cadherin) was unchanged. Pre-incubating HUVECs with TNF-α+hypoxia
EVs significantly increased leukocyte attachment compared to basal level (3.0 ± 0.4-fold
increase (p < 0.05)).
Conclusions
Inflammatory adipocyte EVs induce VCAM-1 production in vascular endothelial cells,
accompanied by enhanced leukocyte attachment. Preventing adipocyte derived EV-induced
VCAM-1 upregulation may offer a novel therapeutic target in the prevention of obesity-driven
cardiovascular disease.
Graphical abstract
Graphical Abstract
Keywords
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Article info
Publication history
Published online: January 24, 2019
Accepted:
January 10,
2019
Received in revised form:
November 21,
2018
Received:
April 27,
2018
Identification
Copyright
© 2019 Elsevier B.V. All rights reserved.
