Abstract 150: Monocyte-Platelet Aggregates Correlate With the Prevalence and Severity of Aortic Aneurysms

Objective: To determine whether monocyte-platelet aggregates (MPA) correlate with aortic aneurysm (AA) prevalence and severity. BACKGROUND: Inflammation and intraluminal thrombus are key hallmarks of complex AA. While monocytes fuel inflammation in AA, the contribution of platelets is unknown. We hypothesized that increased platelet activity yields to MPA that drive AA development and indicate disease severity. Methods: Blood was collected from 49 symptomatic patients admitted for aneurysm repair procedures (8 thoracic and 41 abdominal) and 36 matched controls. All subjects were on aspirin monotherapy. Platelet responsiveness to agonists was characterized by light transmission aggregometry. Flow cytometry analysis allowed leukocytes (CD45+)/monocytes (CD14+)-platelet (CD61+) aggregates (LPA/MPA) measurements in the blood and profiled MPA in post-surgical aneurysm tissues. Results: Platelet aggregation in response to ADP (57% vs. 35% aggregation, pin situ in AA sac, platelets and tissue macrophage activation was characterized. Compared to the non-diseased part of the aorta, diseased section had significantly higher platelet infiltration (7.0% vs 1.2% CD61+ cells, p=0.006) and interaction with CD68+ tissue macrophages (8.3% vs. 0.7%, CD61+ macrophages p=0.03). Notably, macrophages highly expressed the adhesion protein, ICAM-1, in the diseased part (39.6 vs 3.3% in the non-diseased section, p Conclusions: Our data highlights MPA as a novel mediator valuable to predict AA prevalence and severity.