Allograft inflammatory factor-1 augments macrophage phagocytotic activity and accelerates the progression of atherosclerosis in ApoE^-/- mice

Allograft inflammatory factor (AIF)-1, originally cloned from a rat heart allograft under chronic rejection, is induced in various inflammatory conditions including atherosclerosis. Using mouse AIF-1 transfected macrophages and AIF-1 transgenic (AIF-1^Tg) mice, we analyzed the influence of AIF-1 overexpression on macrophage phagocytosis and the development of atherosclerosis. The AIF-1 transfectants showed significantly increased phagocytosis of latex beads and E. coli BioParticles as well as incorporation of acetylated low-density lipoprotein (LDL) compared to those of vector controls. Concordant results were obtained with elicited peritoneal exudate cells from AIF-1^Tg mice. When AIF- 1^Tg mice were crossbred with apolipoprotein E knockout mice (ApoE^-/-), these AIF-1^TgApoE^-/- mice developed significantly increased atherosclerotic lesions compared to ApoE^-/- mice. These results suggest that enhanced AIF-1 expression leads to augmented incorporation of degenerated LDL by macrophages and promotes development of astherosclerotic vasculopathy.