P6070
Oxidized low-density lipoprotein, in contrast to inflammatory cytokines, activates AMPK-ACC signaling in human platelets

Extract

Background: Thrombin is the major platelet agonist responsible for AMP-activated protein kinase, AMPK activation, specific ACCSer79 phosphorylation, and subsequently controls cytoskeleton organization. However, our data showed that the relationship between thrombin generation in vivo and platelet ACC phosphorylation (P-ACC) in coronary artery disease patients is poor. These findings suggest that other factors may affect AMPK-ACC signaling in human platelets. Inflammatory cytokines and more importantly oxidized low-density lipoprotein (oxLDL) can activate platelets and promote platelet prothrombotic functions. The effect of cytokines and oxLDL on platelet AMPK-ACC signaling warrant further investigation.

Aims: The aim of our study was to investigate the impact of inflammatory cytokines (IL1b, IL6, IL10, IL17A, TNFa) and oxLDL on platelet AMPK-ACC signaling.

Methods: Washed platelets from healthy donors, were treated with the above-mentioned cytokines and with Cu2+- and myeloperoxidase-mediated (Mox) oxLDL, prior to lysis and western blot analysis of protein extracts.

Results: Our study showed that these inflammatory cytokines may participate in platelet activation by influencing the P38-MAPK pathway, but they barely affect ACC phosphorylation. However, we demonstrated for the first time that in addition to thrombin and collagen, oxLDL activates the AMPK-ACC signaling in human platelets. Furthermore, we used MoxLDL, a specifically modified ApoB100 lipoprotein and oxPCCD36 (a specific CD36 ligand) to show that platelet AMPK activation lay downstream of CD36. Blocking the CD36 receptor with a monoclonal antibody prevented MoxLDL-induced ACC phosphorylation, confirming CD36 involvement in platelet AMPK activation.