Adhesion molecules in renal disease

Abstract

Adhesion molecules are a heterogeneous class of ligands/receptors that mediate cell adhesion, either to other cells or to the extracellular matrix. Cell adhesion is of fundamental importance to an impressive number of physiological and pathological processes, including the differentiation of cells and their organization in tissues [1], the intercommunication and activation of immune cells [2], the recirculation and migration of white blood cells [3], the growth and metastatic diffusion of tumoral cells [4]. On the basis of molecular, structural and functional differences, adhesion molecules have been separated into three main groups: the integrins, the selectins and a group that belongs to the immunoglobulin superfamily. In addition to these classic families of adhesion molecules, a recently described family of chemoattractive cytokines, termed chemokines, behave as adhesion molecules after having been released at a site of inflammation. These ligands, in fact, bind to specific receptors in the endothelium or extracellular matrix [5] and here regulate immune cell migration by haptotaxis, a process driven by the gradient of adhesive ligands affixed to the surface of cells or to the extracellular matrix [6]. This article first summarizes the features that distinguish the families of adhesion molecules and gives a concise description of their most relevant members. Then, the expression of adhesion molecules in renal cells in culture and in normal renal tissue, and the pathophysiological role of adhesion molecules in renal disease, with an emphasis on nephritis, transplant rejection and the effects of hemodialysis on leukocytes will be reviewed.