Monocyte heterogeneity in obesity and subclinical atherosclerosis

Monocytes and monocyte-derived macrophages have been recognised as the cellular hallmark of atherosclerosis decades ago. Recently, they have also been shown to play a pivotal role in obesity. Monocytes display immunophenotypic heterogeneity with functionally distinct subpopulations. We initiated the I LIKE HOMe study to examine monocyte heterogeneity in obesity and subclinical atherosclerosis. We assessed carotid intima media thickness (IMT), body mass index (BMI), and other cardiovascular risk factors in 622 healthy volunteers. Using flow-cytometry, we differentiated monocytes into CD14(++)CD16(-) and CD16(+) cells, which we further subdivided into CD14(++)CD16(+) and CD14((+))CD16(+) cells. Body mass index was significantly correlated with carotid IMT. High CD16(+) monocyte counts were significantly associated with both higher BMI and increased carotid IMT. Adjustment for CD16(+) monocyte counts weakened the correlation between BMI and carotid IMT, suggesting that the increase in CD16(+) monocyte numbers in obesity may partly explain the association between obesity and IMT. Our results reveal a significant univariate association between CD16(+) monocytes and both obesity and subclinical atherosclerosis in low-risk individuals. They are in line with recent observations that CD16(+) monocytes show high endothelial affinity and a potent capacity to invade vascular lesions and to transform into pro-inflammatory cytokine producing macrophages.