Abstract 21360: Hck and Fgr, Potential Targets for Intervention in Atherosclerosis?
Leukocyte transmigration across the endothelial layer to atherosclerotic plaques is a hot target for clinical intervention which is directed by inflammatory responses and interactions of leukocytess with endothelial cells. Considering that the Src kinases Hck and Fgr play a central role in immune function and cell motility, in this study we evaluated their involvement in atherosclerosis. In vitro experiments were performed with peritoneal macrophages (PM) and bone marrow macrophages (BMM). Two in vivo experiments were set up: First, Fluorescent labelled BMM were injected into LDLr−/− mice with advanced atherosclerotic plaques induced by perivascular collar placement, to evaluate their migration capacity towards established lesions. Second: Female LDLr−/− mice were lethally irradiated and reconstituted with bone marrow deficient in Hck/Fgr for assestment of lesion development. All animals were fed an atherogenic diet during 13 weeks and then sacrificed for analysis. Blood and bone cell composition was analyzed by FACS. Peritoneal macrophages from Hck/Fgr dKO mice exhibited a reduced migratory capacity in vitro (17 fold decrease, P=1E10 - 6). BMM from Hck/Fgr dKO mice had a 42% (P=0.03) reduction in their adhesion with no differences in transmigration to activated endothelial cells . In agreement with these findings, the number of dKO fluorescent labelled BMM that adhered to atherosclerotic plaques in vivo was 66% less than that of WT cells 15 minutes after injection (P=2E-4) leading to 88% fewer transmigrated cells after 1 day (P=1.3E-12). Atherosclerotic lesions formed in Hck/Fgr deficient mice resulted in 36% reduction in lesion size (P=0.01, n=10) and plaque macrophage and neutrophil contents (respectively 34% and 61% reduction, P=1.16E-8 and P=0.02). Necrotic core size did not differ between groups, while fibrous caps and collagen content were markedly smaller, suggesting a reduced stability (fibrous cap: −60% P=0.002; collagen: −80% P=0.0005). In conclusion, deficiency of Hck and Fgr Src kinases leads to reduced atherosclerosis lesion formation accompanied by reduced fibrosis and collagen contents. The accumulation of macrophages in advanced atherosclerotic lesions is blocked by the impaired adhesion of macrophages to the endothelium.
- © 2010 by American Heart Association, Inc.