Protein I/II of Oral Viridans Streptococci Increases Expression of Adhesion Molecules on Endothelial Cells and Promotes Transendothelial Migration of Neutrophilsin Vitro

As accumulation of leukocytes in perivascular tissues is a key step in inflammatory disorders, we have analyzed in the present work the up-regulation of expression of adhesion molecules, such as E-selectin, ICAM-1, and VCAM-1, on human endothelial cells, in response to protein I/II, a modulin fromStreptococcus mutansOMZ 175. Using cultured human saphenous vein endothelial cells (HSVEC), we demonstrated that protein I/II directly and specifically up-regulated E-selectin, ICAM-1, and VCAM-1 expression. We confirmed also that the up-regulation of adhesion molecules in HSVEC is mediated by lectin activity for NANA- and fucose-containing receptors. The ability of protein I/II to promote the transendothelial migration of neutrophils was then examined. Using Transwell inserts, we found that protein I/II, in promoting the up-regulation of adhesion molecule expression, stimulates neutrophil migration through endothelial cells. These events may play a role in the etiology of inflammatory responses leading to the various pathologies associated with oral viridans streptococci.