Absence of microbiota (germ-free conditions) accelerates the atherosclerosis in apoe-deficient mice fed standard low cholesterol diet

Aim: the aim of our work was to determine the influence of intestinal bacteria on the development of atherosclerotic lesions using apolipoprotein e (apoe)-deficient knockout mice. & methods: the experiments were performed on apoe-/-deficient mouse strain c57bl/6,bred under germ-free (gf) conditions for two generations or under conventional conditions with defined microflora (cv). the mice were fed a standard low cholesterol diet or cholesterol-rich diet for 3-4 months. we studied the development of advanced lesions in the thoracic and abdominal aorta by histological,morphometric and immunohistological methods. & results: conventionally reared apoe-/- mice (containing no pathogenic intestinal microbiota) and fed a standard low cholesterol diet in contrast to a high cholesterol diet did not develop atherosclerotic aortic plaques. in contrast,apoe-/- mice reared under germfree conditions for 2 generations and fed a low cholesterol diet exhibited atherosclerotic plaques in the aorta. characteristic lipid deposition with foam cells and macrophages was found in their arterial walls. & conclusion: in contrast to the absence of atherosclerotic plaques in conventionally reared apoe-deficient mice,germ-free apoe-/- mice consuming the same low cholesterol standard diet developed atherosclerotic plaques in the aorta. differences in atherosclerotic plaques between gf and cv apoe-/- mice are not so apparent when mice are fed a high cholesterol diet. our findings thus document the protective effect of microbiota (commensal bacteria) on atherosclerosis development.