Pepducins in Atherosclerosis

Introduction. Cardiovascular disease is the leading cause of illness and death in developed countries and will soon become the pre-eminent health problem world wide. Considering atherosclerosis as an inflammatory process, activation of leukocytes, aggregation of platelets and damage of vascular endothelium are major pathophysiological mechanisms in its progression. Leukocyte migration into injured vasculature plays a role in the onset of atherosclerosis and in the destabilization of atherosclerotic lesions leading to myocardial infarction. Distinct chemokines, their receptors and the G protein-mediated cellular signaling events might play a role in this process. Aim of the study. To elucidate the role of these chemokine receptors in vivo and thus to test a novel therapeutic approach to atherosclerosis, pepducins specific for certain G protein coupled receptors shall be developed. Pepducins are novel palmitoylated peptides based on the third intracellular loop of chemokine receptors and act as receptor-modulating agents by targeting the intracellular surface of the receptor. They allow for the fast in vitro and in vivo elucidation of the functional role of respective G-protein coupled receptors. By virtue of this pepducin- based approach, receptor-modulators for the chemokine receptors CXCR1, CXCR2, CCR5, CXCR4 and CCR2, all of which have been descriptively associated with atherosclerosis, should be developed and in vitro and in vivo characterized with regard to their functional role on leukocytes, platetelets, and endothelium. Finally, these newly developed pepducins shall be tested for their capability to prevent and treat atherosclerosis in a respective mouse- model, namely the ApoE knock-out mouse. Methods. Peptides will be synthesized by standard Fmoc solid-phase synthetic methods with C-terminal amides. The migration inhibitory effect will be tested by chemotaxis assays using human leukocytes. The ability to inhibit respiratory burst and phagocytosis of leukocytes will be tested. Leukocyte-endothelium interactions will be tested using flow-chamber models with monolayers of endothelial cells. Subsequently, the in vivo inhibitory effect of newly derived pepducins will be tested by performing peritoneal lavage migration experiments. Finally, thus far functionally characterized pepducins will be tested for their inhibitory effect on the development of and the treatment of atherosclerosis in the ApoE-/- mouse-model of atherosclerosis. Conclusions. These experiments should reveal the functional role of indicated chemokine receptors in atherosclerosis and should concomitantly derive novel drugs - pepducins - to prevent and treat atherosclerosis, and potentially other inflammatory conditions. A specific chemokine antagonist with clinical efficacy would be predicted to have a much higher therapeutic index than current conventional anti-inflammatory drugs.