EXPRESSION OF VASCULAR ADHESION MOLECULES ON HUMAN ENDOTHELIA IN AUTOIMMUNE THYROID-DISORDERS

Cellular activation and expression of certain adhesion molecules withi n vascular endothelium is a critical event in leucocyte recruitment an d emigration. A wide array of different adhesion receptors has been id entified to mediate the interaction between endothelial cells (EC) and leucocyte subpopulations. In this study, the tissue expression of E-s electin, P-selectin, CD31, and endoglin endothelial cell adhesion mole cules was studied on thyroid tissue from patients with Graves' disease (GD) and Hashimoto's thyroiditis (HT). We found an up-regulated expre ssion of E-selectin in EC in GD and HT thyroids, specifically in those areas more severely inflamed, with no reactivity in control thyroids. P-selectin was basally expressed in postcapillary venules in control glands, with an increased expression in HT and GD glands. On the other hand, increased CD31 expression was found on perifollicular, small an d large venule EC from GD and HT glands, that correlated with the seve rity of mononuclear infiltration. In addition, CD31 expression was obs erved in some intrathyroidal macrophages and T cells in close proximit y to CD31(+) EC. Furthermore, a markedly enhanced expression of endogl in, a transforming growth factor-beta binding protein, was mainly loca ted on perifollicular EC and EC from small venules as well as in adjac ent macrophages from GD and HT thyroid glands. This enhanced expresion of E- and P-selectins, CD31 and endoglin by thyroid EC in GD and HT m ay reflect their ability to regulate leucocyte trafficking and activat ion.