Biomedical Engineering Reference
In-Depth Information
Adhesion Molecules (ICAM-1, VCAM-1, E-selectin,
P-selectin)
During atherosclerotic plaque development the adhesion molecule pathway is
activated. Expressed adhesion molecules attract leukocytes to the endothelium
h e cells then 'roll' along the endothelium (b), become i rmly attached to it (c)
and migrate into the subintimal spaces (d), where they take up lipids to become
foam cells and fatty plaques (Krieglstein and Granger 2001). h e selectin family
of adhesion molecules are involved in the adhesion of leukocytes to the activated
endothelium and the observed cell 'rolling. Two dif erent adhesion molecules
belonging to the Immunoglobulin (Ig) superfamily, ICAM-1 and vascular cell
adhesion molecule 1 (VCAM-1), are involved in the extravasation of leukocytes
into the surrounding tissue. h e expressed endothelial adhesion molecules bind
to their complementary ligands on the leukocytes, many of which belong to the
integrin family. P-selectin is stored in specii c granules that are present in platelets
and endothelial cells from where it is mobilized to the cell surface at er stimulation.
E-selectin, however, is not stored, but increased surface expression can occur in
response to transcription-dependent protein synthesis.
(a)
Cells are attracted to endothelial
receptors.
(b)
The cells 'roll' along the endothelium.
(c)
Firm attachment takes place.
(d) Cells migrate into the subintimal
spaces. Lipids are taken up and the
formation of foam cells and fatty
plaques occurs.
Fig. 2
Diagram showing leukocyte at achment to the endothelial lining via endothelial adhesion
molecules and their receptors. h ese images depict the process whereby leukocytes are at racted
towards and then bind to the endothelial lining. Unpublished computer generated images: M.A.
Miller and S.P. Miller (Poser 7 (c) 1991-2008).
