Circulating immune cell profiles detected by mass cytometry differ significantly between patients with predominantly calcified and predominantly non-calcified coronary atherosclerosis

Abstract Background/Introduction Inflammation is now a well-established component of the pathophysiology of coronary artery disease (CAD), but it is unknown whether atherosclerosis is associated with a distinct circulating immune cell profile. Mass cytometry time-of-flight (CYTOF) is a new precision technology which can be used to assess leukocyte populations comprehensively. Purpose To determine if patients with calcified and non-calcified (soft) coronary plaque have distinct circulating immune cell profiles when compared to healthy controls, and to assess whether this could be used to detect sub-clinical CAD. Methods Patients referred for a CT coronary angiogram were recruited; blood samples were collected and peripheral blood mononuclear cells (PBMCs) were isolated. Imaging data was analysed using a modified Gensini scoring system which incorporated plaque composition, with higher weighting given to soft plaque. The modified Gensini scores were then used to further segregate into calcified-predominant and soft-predominant disease groups. CYTOF analysis was performed on the PBMCs, with groups as outlined in Table 1. Results Age was significantly higher in the CAD+ group, but all other demographic features and risk factors did not differ between groups. Patients with predominantly calcified disease showed an increase in memory CD8 T cells (p=0.004), an increase in CD 39+ CD4 T cells (p=0.028), and a decrease in naïve CD8 T cells (p=0.005), which suggests an accumulated memory response in more quiescent disease. Patients with predominantly soft-plaque disease have higher pro-inflammatory monocyte populations (p=0.013) and proliferative CD4 T cell populations (p=0.011), suggesting acute innate and adaptive responses to biologically active plaque. Conclusions This pilot study has shown that further study should be pursued into the utility of CYTOF to identify sub-clinical CAD through differences in peripheral circulating immune cell profiles. Table 1. Risk Factors and Demographics All Healthy (Gensini = 0) CAD+ (Genini >0) P value Calcified Predominant Soft Predominant P value Number 58 30 28 10 18 Age 61.0 (±11.8) 54.9 (±10.8) 67.6 (±9.1)