Lactadherin deficiency leads to apoptotic cell accumulation and accelerated atherosclerosis in mice

Background - Atherosclerosis is an immunoinflammatory disease; however, the key factors responsible for the maintenance of immune regulation in a proinflammatory milieu are poorly understood. Methods and Results - Here, we show that milk fat globule-EGF factor 8 ( Mfge8, also known as lactadherin) is expressed in normal and atherosclerotic human arteries and is involved in phagocytic clearance of apoptotic cells by peritoneal macrophages. Disruption of bone marrow - derived Mfge8 in a murine model of atherosclerosis leads to substantial accumulation of apoptotic debris both systemically and within the developing lipid lesions. The accumulation of apoptotic material is associated with a reduction in interleukin-10 in the spleen but an increase in interferon-gamma production in both the spleen and the atherosclerotic arteries. In addition, we report a dendritic cell-dependent alteration of natural regulatory T-cell function in the absence of Mfge8. These events are associated with a marked acceleration of atherosclerosis. Conclusions - Lack of Mfge8 in bone marrow - derived cells enhances the accumulation of apoptotic cell corpses in atherosclerosis and alters the protective immune response, which leads to an acceleration of plaque development.