Objectives: Immunoglobulin treatment is known to suppress atherosclerosis in apolipoprotein E-deficient mice. In addition, immunoglobulin inhibits atherosclerosis via the Fc receptors. However, the effect of immunoglobulin treatment at the advanced stage of atherosclerosis is still unclear. This study examined the effects of immunoglobulin on apolipoprotein E-deficient mice at the advanced stage of the disease.
Methods: Atherosclerosis was induced in mice fed a high-fat diet containing 0.3% cholesterol. After confirming the presence of atherosclerotic lesions at 11 weeks, mice were intraperitoneally treated with injections of either intact type of immunoglobulin (1 g/kg/day) or F (ab') 2 fragments of immunoglobulin (1 g/kg/day) on alternate days over 4 weeks. Oil red-O staining and immunohistochemical staining with CD4+ cells were performed of the aorta, and atherosclerotic lesions was evaluated and compared between the groups.
Results: Fatty streak lesion was significantly suppressed by intact immunoglobulin compared with saline, and inflammatory cell infiltration and expression of CD4+ cells were less in mice treated with intact immunoglobulin compared with the control.
Conclusions: Immunoglobulin treatment even at the advanced stage of atherosclerosis suppressed the development of fatty lesions and may stabilize atherosclerotic plaques by inhibiting inflammatory cell expression. Immunoglobulin suppression of atherosclerosis was confirmed to act via the Fc receptors.