EX VIVO MONOCYTES SIGNATURES FROM CORONARY ARTERY DISEASE PATIENTS AND HEALTHY SUBJECTS THROUGH A LIPIDOMIC APPROACH

Abstract

Monocytes play a major role in atherosclerosis, a chronic inflammatory disease of the arterial wall and specifically, the recruitment of circulating monocytes to the site of injury and their diapedesis through the endothelium (extravasation) are crucial events in atherosclerotic plaque progression. Monocytes are classified into three subsets according to the differential expression of the lipopolysaccharide receptor (CD14) and the FcγIII receptor (CD16): CD14++CD16- classical monocytes, intermediate CD14++CD16+ monocytes and non-classical CD14+CD16++. During circulation, monocytes are exposed to several environmental stimuli that may alter their metabolic state thus inducing a cellular reprogramming with important effects on their functional profile. Recent data indicated that subjects with altered blood lipid levels display circulating monocytes with an inflammatory profile. Most of researches investigated the mechanisms by which lipids and lipoproteins affects the monocyte functions leading to plaque formation, but no information about the relationship between cellular lipid composition and monocyte function are available. Aim of the study was to investigate a lipid profile of monocytes in healthy subjects (HS) and coronary artery disease (CAD) patients, and its influence on monocyte migration. Monocyte lipidomic profile was evaluated through an untargeted liquid chromatography-time of flight mass spectrometry platform operating in positive and negative ionization mode. Monocyte migration assay was performed using fetal bovine serum (FBS), or autologous serum as chemotactic stimuli. By means of an untargeted lipidomics approach, we evidence a different profile in CAD monocytes compared to HS, with a marked increase in lactosylceramide (d34:1) (d18:1/16:0) in patient’s monocytes. Moreover, we demonstrate that monocytes obtained from CAD patients show a significant increase in FBS- and autologous serum-mediated migration compared to HS. The lactosylceramide levels positive correlate with monocyte migration and the treatment with the inhibitor of lactosylceramide synthase significantly reduces the monocyte migration. The results of this study suggest that lipidomics profile may dysregulate cell function, such as migration in CAD patients’ monocytes.