The monocytic lineage specific soluble CD163 is a plasma marker of coronary atherosclerosis

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, 1.79–3.5 mg/L) than in CAD− patients (2.09, 1.31–2.72 mg/L) (p = 0.021, Mann–Whitney U-test). Log sCD163 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 log sCD163 correlated with CAD extent (Spearman r = 0.22, p = 0.008), log CRP 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.