Daintain/AIF-1 plays roles in coronary heart disease via affecting the blood composition and promoting macrophage uptake and foam cell formation.

Background: Daintain/AIF-1 is an inflammatory polypeptide factor/allograft inflammatory factor 1 derived from macrophages. It is characterized in APOE(-/-) mice as a novel inflammatory factor associated with atherosclerosis. The purpose of this study was to characterize its function in human atherosclerosis.

Methods: Immunohistochemistry was used to identify the expression of daintain/AIF-1 in vessel segments within and far from atherosclerotic plaques; High-performance liquid chromatography (HPLC) was used to display the effects of daintain/AIF-1 on C-reactive protein (CRP), oxidative capacity and superoxide dismutase (SOD) in vivo; Oil Red O Staining was used to show the effects of daintain/AIF-1 on uptake of oxidized low density lipoprotein (ox-LDL) into U937 cells, a macrophage line; Western Blot was used to test scavenger receptor A (SRA) expression.

Results: A high density of daintain/AIF-1 was observed in the tunica intima and media of coronary artery with atherosclerotic plaque, and fewer daintain/AIF-1 in the vessels without atherosclerotic plaque; Daintain/AIF-1 injected intravenously into BALB/c mice boosted oxidative capacity, significantly impaired SOD activities and augmented the CRP level in blood. According to the oil red O test, daintain/AIF-1 profoundly facilitated the uptake of ox-LDL in U937 macrophages and formation of foam cells in the endothelium. We also found that the molecular mechanisms are effective by promoting overexpression of SRA on macrophages.

Conclusion: These findings implicate that the inflammatory factor daintain/AIF-1 is closely associated with atherogenesis, and could be further characterized as a novel risk factor for atherosclerosis.