LAUSR

BACKGROUND T-lymphocytes plays an important role in the pathophysiology of acute coronary syndromes (ACS). T-cell activation in vitro by pro-inflammatory cytokines may lead to functional Tissue Factor (TF) expression, indicating a possible contribution of immunity to thrombosis. Oxidized low-density lipoproteins (oxLDLs) are found abundantly in atherosclerotic plaques. We aimed at evaluating the effects of oxLDLs on TF expression in T-cells and the role of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). METHODS AND RESULTS CD3+ cells were isolated from healthy volunteers. Gene, protein, and surface expression of TF, as well as of LOX-1, was assessed at different time-points after oxLDL stimulation. To determine whether oxLDL-induced TF was LOX-1 dependent, T-cells were preincubated with a LOX-1 inhibiting peptide (L-RBP) or with an anti-LOX-1 blocking antibody. To exclude that TF expression was mediated by reactive oxygen species (ROS) generation, oxLDL-stimulated T-cells were preincubated with superoxide dismutase (SOD) + catalase or with 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol), an intracellular free radical scavenger. Finally, to determine if the observed findings in vitro may have a biological relevance, the presence of CD3+/TF+/LOX-1+ cells was evaluated by immunofluorescence in human carotid atherosclerotic lesions.OxLDLs induced functionally active TF expression in T-cells in a dose and time-dependent manner, independently on ROS generation. No effect was observed in native LDL-treated T-cells. LOX-1 expression was also induced by oxLDLs in a time- and dose-dependent manner. Pre-incubation with L-RBP or anti LOX-1 antibody almost completely inhibited oxLDL-mediated TF expression. Interestingly, human carotid plaques showed significant infiltration of CD3+ cells (mainly CD8+ cells), some of which were positive for both TF and LOX-1. CONCLUSIONS oxLDLs induce functional TF expression in T-lymphocytes in vitro via interaction of oxLDLs with LOX-1. Human carotid atherosclerotic plaques contain CD3+/CD8+cells that express both TF and LOX-1, indicating that also in patients these mechanisms may play an important role. TRANSLATIONAL PERSPECTIVES Despite significant advancements have been made in antithrombotic therapy, current strategies still fail to prevent acute thrombotic coronary events in a substantial number of patients, indicating that the complex mechanisms underlying the pathophysiology of ACS are not fully elucidated. The present study demonstrates, for the first time, that T-lymphocytes may express functional TF in response to oxLDLs via mechanisms other than the "classical" activation of the T-cell receptor, namely via interaction with LOX-1. Further studies aimed at interfering with LOX-1 in T-lymphocytes might offer innovative and additional therapeutical approaches for ACS patients.