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Charakterisierung alternativer LFA-1 Liganden bei entzündlicher und atherogener Zellrekrutierung

Subject Area Cardiology, Angiology
Term from 2007 to 2015
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 29385330
 
Final Report Year 2015

Final Report Abstract

In this project, we focused on the cell-specific roles of Junctional Adhesion Molecule A (JAM-A) in vascular inflammation and remodeling. Using state-of-the-art microscopy techniques, e.g. atomic force and 2-photon laser scanning microscopy, we could further establish and characterize the important role of endothelial JAM-A in the recruitment of leukocytes. First, we showed that binding of the leukocyte integrin LFA-1 to JAM-A led to a destabilization of the 34mmune34ng34 interaction of JAM-A, a process that has implications for transendothelial migration. During inflammation, JAM-A is both redistributed and proteolytically released from the cell membrane and these processes can subsequently affect leukocyte recruitment to the vascular endothelium. In a relevant mouse model of diet-induced atherosclerosis, the pathophysiologic relevance of endothelial cell- and bone marrow-derived JAM-A was established. Whereas deletion of JAM-A in leukocytes led to an increase of plaque formation, downregulation of endothelial JAM-A resulted in a reduction of atherosclerosis. Multiphoton microscopy revealed a disordered endothelial distribution of JAM-A at sites of plaque development in hyperlipidemic mice, which might facilitate atherogenic monocyte recruitment. Thus, endothelial JAM-A might serve as a molecular beacon guiding leukocytes to sites of developing atherosclerosis. Finally, we have further characterized the role of JAM-A in platelet signaling and confirmed that JAM-A–deficiency in platelets was accompanied by hyperreactivity. As a consequence, JAM-A–deficient platelets appeared to release more chemokines and more avidly interacted with leukocytes and endothelial cells. During the course of a highfat diet, the platelet hyperreactivity in the absence of JAM-A accelerated the development of atherosclerotic plaques in mice. Taken together, the results from this project highlight the versatile and cell-specific roles of JAM-A in the recruitment of leukocytes that drives the development of atherosclerosis.

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