Oxidized laminin-1 induces increased monocyte attachment and expression of ICAM-1 in endothelial cells

Atherosclerosis has been associated with increased oxidative stress and monocyte recruitment by endothelial cells. Sub-endothelial basement membrane proteins, such as laminins that play a central role in cell adhesion, are exposed to reactive oxygen species. In the present study monocyte attachment on human umbilical cord vein endothelial cells (HUVEC) that were preattached to oxidized or native laminin, was investigated. Intracellular cell adhesion molecule-1 (ICAM-1) expression by HUVEC was estimated by an enzyme-linked immunosorbent assay. HUVEC attachment to oxidized or native laminin-1 was examined using the Hemacolor kit. Anti-alphaL, anti-alphaM, anti-alpha2 and anti-beta2 integrin subunit antibodies were used in order to further investigate the above phenomena. HUVEC that were preattached to oxidized laminin expressed higher levels of ICAM-1 and monocytes attached at a higher degree to these cells as compared to HUVEC that were preattached to native laminin. Incubation of monocytes with monoclonal antibodies against the alphaM and beta2 integrin subunits equalized the above mentioned differences. Moreover, HUVEC attached to oxidized laminin at a higher degree as compared to native laminin. This difference was equalized after incubation with the antibody against the alpha2 integrin subunit. These results indicate a modified interaction between HUVEC and the basement membranes in cases where laminin is oxidatively modified. This modified interaction results in increased ICAM-1 expression by endothelial cells and consequently increased monocyte recruitment capacity.