NCIt related terms : Leukocyte transendothelial migration;
Alternative definition : KEGG: Leukocyte migration from the blood into tissues is vital for immune surveillance
and inflammation. During this diapedesis of leukocytes, the leukocytes bind to endothelial
cell adhesion molecules (CAM) and then migrate across the vascular endothelium. A
leukocyte adherent to CAMs on the endothelial cells moves forward by leading-edge
protrusion and retraction of its tail. In this process, alphaL/beta2 integrin activates
through Vav1, RhoA, which subsequently activates the kinase p160ROCK. ROCK activation
leads to MLC phosphorylation, resulting in retraction of the actin cytoskeleton. Moreover,
leukocytes activate endothelial cell signals that stimulate endothelial cell retraction
during localized dissociation of the endothelial cell junctions. ICAM-1-mediated signals
activate an endothelial cell calcium flux and PKC, which are required for ICAM-1 dependent
leukocyte migration. VCAM-1 is involved in the opening of the endothelial passage
through which leukocytes can extravasate. In this regard, VCAM-1 ligation induces
NADPH oxidase activation and the production of reactive oxygen species (ROS) in a
Rac-mediated manner, with subsequent activation of matrix metalloproteinases and loss
of VE-cadherin-mediated adhesion.;