Chemokines are structurally related proteins which form a large family of chemotactic cytokines. They provide a general communication system for cells and regulate lymphocyte migration. These proteins orchestrate the formation of microenvironments in lymphoid tissue, promote lymphoid organogenesis and help foster vascular and lymphatic angiogenesis. In addition to the classical G proteincoupled chemokine receptors, many chemokines also bind to a family of nonsignaling proteins, now called interceptors (chemokine-internalizing proteins). Here we summarize recent data on the role of interceptors in chemokine biology with a focus on renal inflammation.
Atypical Chemokine Receptors in Renal InflammationStephan Segerer a, b Jan Jedlicka a Rudolf P. Wüthrich As inflammatory cells migrate from the bloodstream, a chemokine signal is necessary for firm adhesion to the endothelium of venules. Therefore, chemokines need either to be expressed by endothelial cells, deposited on endothelial surfaces by platelets, or be transported through the endothelial layer, to be presented to passing leukocytes [4] . Having left the vessels, inflammatory cells travel through interstitial tissues most likely following haptotactic (matrix-bound) gradients towards the site of injury [3] . Defined structures of the extracellular matrix, particularly glycosaminoglycans and nonsignaling chemokine-binding proteins, are sites of chemokine presentation, and in the case of the interceptors, also transport [5] . These presenting structures change during inflammation [6] . Additionally, chemokine function is modified by the formation of dimers and multimers, occurring in the ligands and receptors [3] .An additional cascade of interactions between chemokines, soluble mediators, adhesion molecules and chemo-
Key WordsChemokines ؒ Chemokine receptors ؒ Interceptors ؒ Nonsignaling receptor ؒ Duffy antigen/receptor for chemokines Abstract Chemokines are structurally related proteins which form a large family of chemotactic cytokines. They provide a general communication system for cells and regulate lymphocyte migration. These proteins orchestrate the formation of microenvironments in lymphoid tissue, promote lymphoid organogenesis and help foster vascular and lymphatic angiogenesis. In addition to the classical G protein-coupled chemokine receptors, many chemokines also bind to a family of nonsignaling proteins, now called interceptors (chemokine-internalizing proteins). Here we summarize recent data on the role of interceptors in chemokine biology with a focus on renal inflammation.