Reduced Membrane CD163 Expression in 7-Oxysterol-Induced Apoptosis Accompanied by Elevated Oxidative Stress

CD163 is a transmembrane scavenger receptor predominantly expressed by activated M2-like macrophages and is involved in inflammatory processes. Oxysterols, which accumulate in atherosclerotic lesions, are known to induce oxidative stress and apoptosis in macrophages. However, the relationship between CD163 expression and apoptosis induced by oxysterols remains poorly understood. Our brief report presents an examination of the effects of an atheroma-relevant mixture of 7β-hydroxycholesterol and 7-ketocholesterol (2mix) on cell surface CD163. THP-1 monocytes/macrophages were exposed to 2mix, and the surface expressions of CD163, apoptosis, and reactive oxygen species (ROS) production were assessed using flow cytometry and fluorescence microscopy. Exposure to 7-oxysterols induced a dose-dependent reduction in cell surface CD163 expression, with significant decreases observed in R1 and R2 cell populations but not in R3. This decrease was accompanied by a significant increase in apoptosis and ROS production. Notably, CD163 expression was inversely correlated with both apoptotic cell death and oxidative stress levels. Our findings suggest that macrophage surface CD163 may exert a protective role against 7-oxysterol-induced apoptosis and oxidative stress. This indicates a potential function of CD163 in macrophage survival and highlights its possible importance for plaque stability in atherosclerotic lesions.