Background: CD163 is a monocyte-macrophage lineage specific scavenger receptor that mediates the uptake and clearance of haptoglobin-haemoglobin complexes, and soluble CD163 (sCD163) is also present in plasma. As atherosclerosis involves infiltration by monocyte-derived macrophages, we investigated whether sCD163 may act as a marker of coronary atherosclerosis (CAD).
Methods and results: Clinical features were identified and plasma was collected from 147 consecutive patients presenting for coronary angiography. Patients were classified as having CAD+, or being free of CAD- haemodynamically significant (>50% luminal diameter) coronary stenoses in one or more major coronary arteries (1, 2 or 3 vessel disease), and sCD163 concentration was measured by ELISA. Plasma sCD163 was non-parametrically distributed, being significantly higher in CAD+ patients (median 2.47 mg/L, 25th-75th percentile, 1.79-3.5mg/L) than in CAD- patients (2.09, 1.31-2.72 mg/L) (p=0.021, Mann-Whitney U-test). LogsCD163 increased significantly with increasing CAD extent (p=0.0036) and was significantly greater in patients with 3 vessel disease than in CAD- patients (p<0.001). Whereas logsCD163 correlated with CAD extent (Spearman r=0.22, p=0.008), logCRP did not, and sCD163 was only weakly correlated with CRP (r=0.19, p=0.039). Importantly, multivariate linear regression identified that sCD163 (p=0.0021) was a significant predictor of CAD extent and was independent of conventional risk factors age (p<0.0001), hypercholesterolemia (p=0.0023), hypertension (p=0.068), and current smoking (p=0.066).
Conclusions: The monocyte-specific marker sCD163 is a novel potential plasma marker of coronary atherosclerotic burden.