Background: Increased inflammatory activity destabilizes the atherosclerotic lesion and may lead to atherothrombosis and symptomatic cardiovascular disease. Co-stimulatory molecules, such as CD137, are key regulators of inflammation, and CD137 activity regulates inflammation in experimental atherosclerosis. Here, we hypothesized that CD137 activation promotes carotid artery inflammation and atherothrombosis.Methods and Results:In a model of inducible atherothrombosis with surgical ligation of the right carotid artery and a subsequent placement of a polyethene cuff, elevated levels of CD137 and CD137 ligand mRNA in atherothrombotic vs. non-atherothrombotic murine carotid lesions was observed. Mice treated with the CD137 agonistic antibody 2A showed signs of increased inflammation in the aorta and a higher proportion of CD8+T cells in spleen and blood. In carotid lesions of 2A-treated mice, significantly higher counts of CD8+and major histocompatibility (MHC)-class II molecule I-Ab+cells were observed. Treatment with the CD137 agonistic antibody 2A did not significantly affect the atherothrombosis frequency in 16-week-old mice in this model.
Conclusions: Levels of CD137 and CD137 ligand mRNA were higher in advanced atherosclerotic disease compared to control vessels, and treatment with the CD137 agonistic antibody 2A, in a murine model for inducible atherothrombosis promoted vascular inflammation, but had no significant effect on atherothrombosis frequency at this early disease stage.
Keywords: 4-1BB; Atherosclerosis; Co-stimulation; Cytokines; Leukocytes.