Faculty Bibliography

Accelerated atherosclerosis in patients with diabetes is a major cause of their morbidity and mortality, and it is unresponsive to therapy aimed at restoring relative euglycemia. In hyperglycemia, nonenzymatic glycation and oxidation of proteins and lipids results in the accumulation of irreversibly formed advanced glycation endproducts. These advanced glycation endproducts engage their receptor in cells of the blood vessel wall, thereby activating mechanisms linked to the development of vascular lesions. We report here a model of accelerated and advanced atherosclerosis in diabetic mice deficient for apolipoprotein E. Treatment of these mice with the soluble extracellular domain of the receptor for advanced glycation endproducts completely suppressed diabetic atherosclerosis in a glycemia- and lipid-independent manner. These findings indicate interaction between the advanced glycation endproducts and their receptor is involved in the development of accelerated atherosclerosis in diabetes, and identify this receptor as a new therapeutic target in diabetic macrovascular disease

A soluble monomeric form of Alzheimer's amyloid-beta (1-40) peptide (sAbeta1-40) is present in the circulation and could contribute to neurotoxicity if it crosses the brain capillary endothelium, which comprises the blood-brain barrier (BBB) in vivo. This study characterizes endothelial binding and transcytosis of a synthetic peptide homologous to human sAbeta1-40 using an in vitro model of human BBB. 125I-sAbeta1-40 binding to the brain microvascular endothelial cell monolayer was time dependent, polarized to the apical side, and saturable with high- and low-affinity dissociation constants of 7.8+/-1.2 and 52.8+/-6.2 nM, respectively. Binding of 125I-sAbeta1-40 was inhibited by anti-RAGE (receptor for advanced glycation end products) antibody (63%) and by acetylated low density lipoproteins (33%). Consistent with these data, transfected cultured cells overexpressing RAGE or macrophage scavenger receptor (SR), type A, displayed binding and internalization of 125I-sAbeta1-40. The internalized peptide remains intact > 94%. Transcytosis of 125I-sAbeta1-40 was time and temperature dependent, asymmetrical from the apical to basolateral side, saturable with a Michaelis constant of 45+/-9 nM, and partially sensitive to RAGE blockade (36%) but not to SR blockade. We conclude that RAGE and SR mediate binding of sAbeta1-40 at the apical side of human BBB, and that RAGE is also involved in sAbeta1-40 transcytosis

In Alzheimer disease (AD), neurons are thought to be subjected to the deleterious cytotoxic effects of activated microglia. We demonstrate that binding of amyloid-beta peptide (Abeta) to neuronal Receptor for Advanced Glycation Endproduct (RAGE), a cell surface receptor for Abeta, induces macrophage-colony stimulating factor (M-CSF) by an oxidant sensitive, nuclear factor kappaB-dependent pathway. AD brain shows increased neuronal expression of M-CSF in proximity to Abeta deposits, and in cerebrospinal fluid from AD patients there was approximately 5-fold increased M-CSF antigen (P < 0.01), compared with age-matched controls. M-CSF released by Abeta-stimulated neurons interacts with its cognate receptor, c-fms, on microglia, thereby triggering chemotaxis, cell proliferation, increased expression of the macrophage scavenger receptor and apolipoprotein E, and enhanced survival of microglia exposed to Abeta, consistent with pathologic findings in AD. These data delineate an inflammatory pathway triggered by engagement of Abeta on neuronal RAGE. We suggest that M-CSF, thus generated, contributes to the pathogenesis of AD, and that M-CSF in cerebrospinal fluid might provide a means for monitoring neuronal perturbation at an early stage in AD

Amyloid-beta peptide is central to the pathology of Alzheimer's disease, because it is neurotoxic--directly by inducing oxidant stress, and indirectly by activating microglia. A specific cell-surface acceptor site that could focus its effects on target cells has been postulated but not identified. Here we present evidence that the 'receptor for advanced glycation end products' (RAGE) is such a receptor, and that it mediates effects of the peptide on neurons and microglia. Increased expressing of RAGE in Alzheimer's disease brain indicates that it is relevant to the pathogenesis of neuronal dysfunction and death

Exposure of proteins to reducing sugars results in nonenzymatic glycation with the ultimate formation of advanced glycation end products (AGEs). One means through which AGEs modulate cellular functions is through binding to specific cell surface acceptor molecules. The receptor for AGEs (RAGE) is such a receptor and is a newly identified member of the immunoglobulin superfamily expressed on endothelial cells (ECs), mononuclear phagocytes (MPs), and vascular smooth muscle cells (SMCs) in both vivo and in vitro. Binding of AGEs to RAGE results in induction of cellular oxidant stress, as exemplified by the generation of thiobarbituric acid-reactive substances, expression of heme oxygenase type I, and activation of the transcription factor NF-kB, with consequences for a range of cellular functions. AGEs on the surface of diabetic red cells enhance binding to endothelial RAGE and result in enhanced oxidant stress in the vessel wall. By using reagents to selectively block access to RAGE, the role of this receptor in AGE-mediated perturbation of cellular properties can be dissected in detail

Proteins or lipids exposed to aldose sugars undergo initial and ultimately irreversible modification resulting in the formation of so-called advanced glycation end-products (AGEs). AGEs are postulated to be especially important in the setting of diabetes mellitus due to hyperglycaemia characteristic of this disorder. Our work has demonstrated that one of the principal means by which AGEs interact with the vascular wall is by interaction with their cellular receptor, the receptor for advanced glycation end-products (RAGE), which is present on the surface of endothelial cells, smooth muscle cells, mesangial cells, mononuclear phagocytes and certain neurons. AGEs interact with RAGE, resulting in the induction of monocyte chemotaxis as well as oxidant stress. One of the consequences of AGE-RAGE-induced cellular oxidant stress is the enhanced expression of vascular cell adhesion molecule-1 on the endothelial surface, a critical consequence of which is the attraction of mononuclear phagocytes into the vessel wall. In both cases, the pro-inflammatory effects of AGEs may be inhibited in the presence of RAGE blockade, using either anti-RAGE F(ab')2 or soluble RAGE, the extracellular domain of the molecule. These data suggest that inhibition of RAGE may interfere with monocyte chemotaxis and attraction into the vessel wall where AGEs deposit/form, suggesting the potential of this intervention to interfere with a critical step in the development of vascular disease, especially in patients with diabetes