Stratification of Patients with Coronary Artery Disease by Circulating Cytokines Profile: A Pilot Study

Abstract

Coronary artery disease (CAD) is a long-term inflammatory process, with atherosclerosis as its underlying pathophysiological mechanism. Endothelial dysfunction is the first step towards atherosclerosis, where damaged endothelial cells release large amounts of pro-inflammatory cytokines and mediators, thus promoting vascular inflammation and disease progression. However, the correlation between serum cytokines and CAD severity remains to be defined. Serum samples from patients performing cardiac computed tomography for suspected CAD (n = 75) were analyzed with a multiplex bead-based immunoassay panel for simultaneous assessment of the concentration of 11 cytokines using flow cytometric technology. The analysis showed statistically significant increases in sRAGE, CCL2_MCP1, FLT1, and IL6 levels in CAD patients compared with healthy subjects and a gradual increase trend towards a more severe form of the disease for most cytokines (e.g., sCD40L, FLT1, sRAGE, CCL2-MCP1, TNFα). Lastly, we explored the performance of cytokines in predicting the diagnosis of CAD and found that an increase in IL6 levels will increase the odds of being non-obstructive CAD-positive. In contrast, an increase in CCL2-MCP1 or FLT1 levels will increase the probability of being obstructive CAD-positive. These results suggest that the combination of serum cytokines may contribute to the not-invasive stratification risk for patients with suspected CAD.

Keywords: cardiovascular disease; coronary artery disease; diagnostic markers; inflammation cytokines.

Figure 1

Distribution of different cytokine serum concentrations in CTRL and CAD groups. For each cytokine, boxplots show the concentration in CTRL and CAD. Statistical differences were calculated by using the Wilcoxon test (* p ≤ 0.05; ** p ≤ 0.01; *** p ≤ 0.001).

Figure 2

Cytokine serum concentrations in CTRL, non_obCAD, and obCAD. The heatmap shows the mean concentration of each cytokine in the 3 groups. Levels of each cytokine (rows) were averaged within the pre-classified group (column). Unsupervised hierarchical clustering is also reported between cytokines and between groups.

Figure 3

Correlation plots. Correlograms show the Spearman’s correlation between cytokine levels and clinical variables in (A) CTRL subjects, (B) non_obCAD, and (C) obCAD patients. The circle size is scaled by the correlation coefficient. Blue and red colors designate, respectively, the positive and negative correlations (* p ≤ 0.05; ** p ≤ 0.01; *** p ≤ 0.001).

Figure 4

Receiver operating characteristic (ROC) curve for (A) IL6 in non_obCAD, (B) CCL2-MCP1, and (C) Flt1 in obCAD. The diagonal represents the reference line. The solid line represents the ROC curve of the cytokine.

Figure 5

Grafical abstract, (A) healthy artery, (B) non-obstructive artery, (C) obstructive artery, (D) grafical illustration.