S100 protein is expressed in induced atherosclerotic lesions of hypercholesterolaemic rats

We have previously identified S100 positive dendritic cells (vascular dendr itic cells) in atherosclerotic lesions of human large arteries. The aim of this study was to determine whether S100 protein is expressed in atheroscle rotic lesions of hypercholesterolaemic rats. Specimens of aorta were obtain ed from 10 healthy rats, and from 30 rats kept on an atherogenic diet for 1 0 and 20 weeks. Immunohistochemical analysis, utilising an en face immunost aining technique and an avidin-biotin complex immunoperoxidase method, demo nstrated S100 immunoreactivity in the aortic intima of the hypercholesterol aemic rats. No expression of S100 protein was detected in the aortic intima of healthy animals. The S100 protein was expressed by intimal cells, which were distributed irregularly throughout the aorta but were frequently loca ted at arterial branch-points and within atherosclerotic lesions. This is t he first report which demonstrates S100 protein expressing cells in atheros clerotic lesions of hypercholesterolaemic rats. This finding might provide a new approach to investigating the functional significance of S100 positiv e cells in atherogenesis.