Plasma proteomic analysis of patients with Coronary Artery Disease with different levels of apolipoprotein CIII

BACKGROUND: Coronary artery disease (CAD) is a multifactorial condition, involving alsogenetic factors. Among candidate genes associated with CAD risk there are lipoprotein lipase (LPL)gene and APOC3 gene. APOC3 encodes for the apolipoprotein CIII (ApoCIII) which acts as aninhibitor of LPL. Three different ApoCIII glycoforms (with different LPL inhibitory activity) -characterized by none, one or two sialic acids - have been described. Changes in the relativeabundance of these glycoforms have been observed in a variety of pathologies.The aim of this study was to analyze and quantify the apoCIII glycoforms and to assess theirrelationship with LPL activity and with the levels of the LPL activator apoA-V.METHODS: ApoCIII glycoforms in four groups of patients (from “Verona Heart Study” biobank,)classified according to the total plasma concentration of ApoCIII and different TG levels, wereanalyzed by a classical (isoelectric focusing/western blotting) and by a shotgun MS approach. LPLactivity (Fluorescent assay) and ApoA-V concentration (ELISA assay) were determined, and theircorrelations with lipid metabolism parameters were analyzed. We also validated by 2D-WB someproteins previously identified by 2-DE analysis.RESULTS Our results indicate that the distribution of the three ApoCIII glycoforms in the selectedgroups of patients are related to the TG levels, particularly the mono-sialylated isoform (ApoCIII-1)prevails in patients with the highest TG levels. A positive correlation between apoCIII and TGlevels as well a positive correlation between TG and more glycosylated ApoCIII were observed.Moreover, investigating the relation among ApoA-V level, LPL activity and the other parameters oflipid metabolism, we obtained useful information on their interplay as anti-atherogenic factor. Finally2D-WB patterns of serum proteins (i.e. Fibrinogen beta/gamma chain, Complement C3) confirmed thetrend in previously proteomics experiments.CONCLUSIONS: These data could provide important insights regarding the interaction amongapoCIII glycoforms, ApoA-V level and LPL activity in predicting cardiovascular risk inpredisposed individuals.