P-selectin Glycoprotein Ligand-1 Plays a Crucial Role in the Selective Recruitment of Leukocytes Into the Atherosclerotic Arterial Wall

Leukocyte recruitment to the arterial vessel wall is the first step in the development of atherosclerotic lesions. Leukocyte homing in this event proceeds through a well-defined adhesion cascade, which includes tethering, rolling, adhesion, and transmigration. Selectins, including the P-, E-, and L-selectins, and their ligands mediate the initial tethering and rolling. Interactions between selectins and their ligands serve as a braking system to decelerate fast-flowing leukocytes from the central blood stream and enable them to adhere to and transmigrate underneath the activated endothelium. The best characterized ligand for selectins is P-selectin glycoprotein ligand-1, an extended homodimeric mucin on leukocytes that binds to all three selectins. Recent studies show that differential expression or glycosylation of P-selectin glycoprotein ligand-1 in different leukocytes mediates selective recruitment of different subsets of monocytes or lymphocytes to atherosclerotic arteries.