Identification of circulating monocytes with a metabolic
phenotype.
Peripheral blood was obtained from healthy individuals to analyse
metabolic markers in circulating monocytes. Cell staining was performed
as described in materials and methods. Cells were analysed by
multi-parametric flow cytometry. We used ABCA1, CD36 and PLIN2 to define
the metabolic population (Fig 1A). Interestingly, with this strategy, we
proved by the first time the presence in bloodstream of monocytes with
metabolic phenotype (MoMe). We could identify two populations according
to the ABCA1 and CD36 expression (3.4%, 1.93%-9%, median and IQR) or
ABCA1, CD36 and PLIN2 expression (2.05%, 0.95%-4.17%, median and IQR
respectively) (Fig 1B). Since a common marker for the study of monocytes
is CD14, we decided to evaluate this molecule expression in metabolic
monocytes (Fig 1C), we found that in each subject, there are metabolic
monocytes with different CD14 expression levels. We found a range from a
small population that does not express this marker (6.83%,
3.33%-14.08%median and IQR), to CD14 positive metabolic monocytes with
dim (31.05%, 20.48%-40.78%, median and IQR) and high expression, but
the most predominant fraction was the one with high expression of CD14
(p<0.0001, 58.75%, 43.13%-75.33%, median and IQR).