Abstract 583: Receptor for Advanced Glycation End Products (Ager) and Diaphanous-1 (Drf1) Suppress Macrophage Reverse Transendothelial Migration and Regression of Diabetic Atherosclerosis
Macrophages display complex trafficking properties in vivo, involving interaction with vascular endothelial cells. Macrophage migration is an important mechanism linked to the progression and regression of atherosclerosis. The underlying mechanisms involved in these processes are not fully defined. RAGE is a multiligand cell surface macromolecule, which binds distinct ligands. The RAGE cytoplasmic domain interacts with Diaphanous-1 (Drf1), both in vitro and in vivo and this interaction is essential for RAGE ligand-mediated signaling in macrophages. We tested the hypothesis that RAGE and Diaphanous-1 suppress regression of diabetic atherosclerosis; at least in part by impaired reduction of plaque macrophage content in an AGE-enriched diabetic environment. In a aorta transplantation model, we examined the morphologic changes in LDLr-/- donor plaques found in Ager-/-, Drf1-/- or WT recipient diabetic mice. After lipid normalization into Ager-/- recipient diabetic mice, we observed reduced plaque macrophage density (CD68 -46%;p<0.05), but increased plaque collagen (PSR+43%;p<0.06), compared to WT diabetic recipients. Oil Red O staining for fatty deposit suggests a decrease (-51%;p<0.05) in plaque area stained and lower AGE staining (-32%;p<0.05) in diabetic Drf1-/- recipient mice compared to WT diabetic recipients. We employed a monocyte bead-tracking model in this in vivo aorta transplantation study. In WT recipient mice, when the donors were LDLr-/- mice fed a western diet, bead frequency per plaque section was reduced (22%;p< 0.05) on day 5 post-transplant compared with baseline. In contrast, bead frequency per plaque section was significantly reduced by (41%;p< 0.05) compared with baseline in the absence of Ager (gene encoding RAGE). In vitro, in a reverse transendothelial migration assay using primary aortic endothelial cells and Ager or Drf1 deficient bone marrow derived macrophages (BMDMs), revealed in the setting of treatment with RAGE ligand AGEs, deletion of Ager or Drf1 in BMDMs facilitated macrophage reverse migration vs. that observed in WT BMDMs. Therefore, we propose that deletion of Ager or Drf1 in recipient diabetic mice accelerates atherosclerotic plaque regression, via reduction in lesional macrophage content.
Author Disclosures: L.M. Senatus: None. Q. Li: None. R. Rosario: None. J. Liu: None. H. Li: None. Y. Vengrenyuk: None. E. Distel: None. T. Barrett: None. G. Daffu: None. X. Shen: None. R. Ramasamy: None. E. Fisher: None. A. Schmidt: None.
- © 2015 by American Heart Association, Inc.