The effect of aging and smoking on the phagocytosis of apoptotic cells in alveolar macrophages

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Our aims of this study are to examine expressions of various receptors for recognition and/or clearance of apoptotic cells on macrophages and assess the relationship with aging and/or smoking. The expression of phosphatidylserine receptor (PSR) and scavenger receptor A (SR-A) in alveolar macrophages was downregulated in smokers when compared to lifelong non-smokers only in the older subjects, but not in younger subjects. The expression of PSR is elevated on U937-derived macrophage like cells if these are incubated in CSE. The cigarette smoke extract-induced upregulation of PSR was inhibited by the vascular endothelial growth factor (VEGF) receptor blockade, SU5614, in U937-derived macrophage-like cells. These results showed that VEGF was indirectly associated with the ability to phagocytose apoptotic cells through the expression of PSR.