The receptor for advanced glycation end products (RAGE) is a central mediator of the interaction of AGE-beta2microglobulin with human mononuclear phagocytes via an oxidant-sensitive pathway. Implications for the pathogenesis of dialysis-related amyloidosis.

Abstract

An important component of amyloid fibrils in dialysisrelated amyloidosis is a form of ␤ 2 microglobulin modified with advanced glycation end products (AGEs) of the Maillard reaction, known as AGE-␤ 2 M. We demonstrate here that the interaction of AGE-␤ 2 M with mononuclear phagocytes (MPs), cells important in the pathogenesis of the inflammatory arthropathy of dialysis-related amyloidosis, is mediated by the receptor for AGEs, or RAGE.125 I-AGE-␤ 2 M bound to immobilized RAGE or to MPs in a specific, dose-dependent manner ( K d Ϸ 53.5 and Ϸ 81.6 nM, respectively), a process inhibited in the presence of RAGE blockade. AGE-␤ 2 M-mediated monocyte chemotaxis was prevented by excess sRAGE or anti-RAGE IgG. Induction of tumor necrosis factor-␣ (TNF) expression by MPs exposed to AGE-␤ 2 M resulted from engagement of RAGE, as appearances of TNF transcripts and TNF antigen release into culture supernatants were prevented by addition of sRAGE, a process mediated, at least in part, by oxidant stress. AGE-␤ 2 M reduced cytochrome c and the elaboration of TNF by MPs was inhibited by N -acetylcysteine. Consistent with these data, immunohistochemical studies of AGE-laden amyloid deposits of a long-term hemodialysis patient revealed positive staining for RAGE in the MPs infiltrating these lesions. These data indicate that RAGE is a central binding site for AGEs formed in vivo and suggest that AGE-␤ 2 M-MP-RAGE interaction likely contributes to the initiation of an inflammatory response in amyloid deposits of long-term hemodialysis patients, a process which may ultimately lead to bone and joint destruction. ( J. Clin. Invest. 98:1088-1094.) Key words: glycated proteins • cytokines • long-term hemodialysis patients • monocyte • amyloidosis IntroductionProteins or lipids exposed to aldose sugars undergo nonenzymatic glycation and oxidation (1-7). Initially, the reversible early glycation adducts form, the best known of which is hemoglobin A 1c, used as an index of glycemic control in diabetic patients. After further complex molecular rearrangements, the irreversible advanced glycation end products (AGEs) 1 form. Conditions favoring AGE formation include those in which protein/lipid turnover is prolonged or delayed on lysine-rich structures, especially in the setting of elevated levels of aldose sugars, such as in diabetes. AGE formation can occur even in the euglycemic state, as in hypercholesterolemic rabbits without diabetes, in which macromolecules are trapped in the expanded neointima in atherosclerosis-prone animals (8).While the generation of AGEs is particularly likely in the diabetic milieu given relatively sustained hyperglycemia (1-4), the tendency toward generation of AGEs is also favored on long-lived proteins, such as those central in the pathogenesis of amyloidoses. In Alzheimer's disease, AGE modification occurs on components of the intracellular neurofibrillary tangles and in extracellular amyloid-␤ peptide (9-11). In a different context, renal failure presents a unique pathophysiological setting for the d...

N ε-(Carboxymethyl)Lysine Adducts of Proteins Are Ligands for Receptor for Advanced Glycation End Products That Activate Cell Signaling Pathways and Modulate Gene Expression

“…In this context, previous studies indicated that heterogenous AGEs, especially those derived from in vivo sources, were signal-transducing ligands of RAGE. Specifically, interaction of AGE-␤ 2 -microglobulin, isolated from the urine of subjects with renal failure and DRA, with cellular RAGE resulted in enhanced MP migration and generation of proinflammatory cytokines such as tumor necrosis factor-␣ (16). Since recent studies have shown AGE-␤ 2 M itself to be quite heterogeneous, composed at least in part of AGEs such as pentosidine, CML, and imidizalone (55)(56)(57), it was important to begin to delineate those specific AGEs that interacted with RAGE.…”

“…Mononuclear Phagocytes-Previous studies from our laboratory indicated that MP properties are significantly modulated upon ligation of RAGE by heterogeneous AGEs, either those prepared in vitro or those derived from in vivo sources, such as AGEs isolated from diabetic plasma, or AGE-␤ 2 -microglobulin isolated and purified from the urine/plasma of subjects with DRA (16). It was thus important to determine if CML adducts, present in these preparations, could activate RAGE on MPs causing cellular migration and activation in this setting (54).…”

HLA–B27 up‐regulation causes accumulation of misfolded heavy chains and correlates with the magnitude of the unfolded protein response in transgenic rats: Implications for the pathogenesis of spondylarthritis‐like disease

“…A second, non-mutually exclusive, possibility is that overproduction of Hu␤ 2 m has biologic effects that converge with those of the UPR. A significant body of literature shows that serum ␤ 2 m becomes glycated over time, and that advanced glycation end products interact with receptors for advanced glycation end products, leading to NF-kB activation, which can amplify immune and inflammatory responses (27,28). For example, ␤2-microglobulin modified with advanced glycation end products delays monocyte apoptosis and results in increased production of proinflammatory TNF␣ and IL-1␤ (29).…”

Interaction of the Receptor for Advanced Glycation End Products (RAGE) with Transthyretin Triggers Nuclear Transcription Factor kB (NF-kB) Activation

“…of iodination damage in enhancing the interaction of proteins with RAGE is the fact that several proteins when iodinated, do not bind this receptor, as is the case of native albumin and native ␤ 2 -microglobulin, whereas their iodinated advanced glycation end products do (Miyata et al, 1996;Schmidt et al, 1994).…”