Scavenging, signalling and adhesion coupling in macrophages: Implications for atherogenesis

Integrins are in physical association and functional cooperation with other membrane proteins that include receptors with scavenger functions, glycosyl-phosphatidylinositol-linked receptors, the family of integrin associated multimembrane spanning signalling proteins and possibly other less characterized proteins with a coupling or signalling function. Monocyte adhesion, migration and differentiation to phagocytically active scavenger cells are directly coupled processes, involving integrins as common transducers for a panel of integrin-linked specific receptors, which assemble a master cluster to coordinate adhesion, migration, scavenging and associated metabolic pathways of the lysosomal and secretory route, and also processes involved in host response. As macrophages represent highly heterogeneous cells that have major phenotypical and functional differences associated with specific patterns of integrin expression, the functional cooperation of integrins with scavenger receptors has to be related to specialized subsets of monocytes and macrophages as well as to ligand specific effects which mediate receptor coupling.