Immunohistochemical Studies on Annexin I and II in Takayasu Arteritis

Abstract

Annexin I and II are classical types of the annexin family and known for their physiological functions in inflammatory processes and thrombus formation. Takayasu arteritis, on the other hand, is a vasculitis of unknown etiology characterized by the inflammatory involvement of the internal vessel wall and thrombus formation. It causes the stenotic andlor obstructive changes of the arterial wall leading to the characteristic clinical feature of pulselessness. Expression of annexin I and II in vessel walls obtained from nine patients with Takayasu arteritis was studied immuno-histochemically to investigate their roles in this morbid condition. Expression of annexin I was recognized in foamy cells in the thickened intima andlor medial layer and in inflammatory cells in vessel walls, but neither in endothelial cells nor in normal or proliferated smooth muscle cells. Strong expression of annexin II was present in foamy cells as well as in endothelial cells both in thickened intima and in proliferated smooth muscle cells in the intima, but not in smooth muscle cells in the media. The stronger expression of annexin II was seen in the endothelial cells in the vasa vasorum of both thickened and normal adventitia. These results suggest the participation of annexin I and II in the process of this vasculitis, and an essential role of vasa vasorum in the pathogenesis of Takayasu arteritis.