Leukocyte-Independent Effects of CC-Chemokines on Vascular Remodeling

Vascular remodeling is an alteration in the structure of vessels in response to injury or hemodynamic changes. Disturbance of the structural and functional integrity of the endothelial cell layer can be observed in vascular remodeling associated with inflammation. Chemokines have been implicated in a wide range of diseases with prominent inflammatory components, and also in vascular remodeling. Among them, CC-chemokines are of great interest. They act through conventional CC-chemokine receptors (CCRs), widely expressed by leucocytes and especially monocytes, which are attracted to sites of chronic inflammation. However, much experimental data shows that CCRs are expressed by vascular cells, suggesting a direct, leukocyte-independent effect on vascular remodeling. Here we discuss the role of CC-chemokines in atherosclerosis, angiogenesis, restenosis and renal dysfunction through direct activation of endothelial cells, endothelial progenitors, vascular smooth muscle cells, platelets, mesangial cells and fibroblasts. The pathophysiological role of CC-chemokines has become more interesting since the discovery of Duffy antigen receptor for chemokines (DARC), a member of the atypical chemokine receptor (ACKR) subfamily, that does not couple with G proteins and fails to transmit conventional intracellular signals. It has been demonstrated to be a chemokine scavenger or decoy receptor with a role in regulation of acute inflammatory responses. At vascular level, ACKRs are expressed by endothelial cells and endothelial lymphatic cells that seem to regulate angio- and lymph-angiogenesis. Pleiotropic effects of CC-chemokines on vascular wall cells and leukocytes increase their importance in vascular remodeling and suggest new drugs to counteract vascular dysfunction.