beta 2-Microglobulin modified with advanced glycation end products is a major component of hemodialysis-associated amyloidosis.

Abstract

Abstract,32-Microglobulin (#2M) is a major constituent of amyloid fibrils in hemodialysis-associated amyloidosis, a complication of long-term hemodialysis patients. Amyloid fibril proteins were isolated from connective tissues forming carpal tunnels in hemodialysis patients with carpal tunnel syndrome. Two-dimensional polyacrylamide gel electrophoresis and Western blotting demonstrated that most of the fl2M forming amyloid fibrils exhibited a more acidic pI value than normal ,B2M. This acidic /@2M was also found in a small fraction of f2M in sera and urine from these patients, whereas heterogeneity was not observed in healthy individuals. We purified acidic and normal iB2M from the urine of long-term hemodialysis patients and compared their physicochemical and immunochemical properties. Acidic ,62M, but not normal 6l2M, was brown in color and fluoresced, both of which are characteristics of advanced glycation end products (AGEs) of the Maillard reaction. Immunochemical studies showed that acidic #2M reacted with anti-AGE antibody and also with an antibody against an Amadori product, an early product of the Maillard reaction, but normal f2M did not react with either antibody. Incubating normal I2M with glucose in vitro resulted in a shift to a more acidic pI, generation of fluorescence, and immunoreactivity to the anti-AGE antibody. The #2M forming amyloid fibrils also reacted with anti-AGE antibody. These data provided evidence that AGE-modified

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

“…and, indeed, natural aging, albeit to a lesser degree, has suggested their potential contribution to the pathogenesis of complications that typify these conditions (3)(4)(5)(6)(7). Our previous studies demonstrated that both in vitro and in vivo derived heterogeneous AGEs ligate cell surface RAGE on endothelium (ECs), mononuclear phagocytes (MPs), vascular smooth muscle (VSMC), and neurons to activate cell signaling pathways such as ERK1/ERK2 kinases and NF-B (8 -9), thereby redirecting cellular function in a manner linked to expression of inflammatory and prothrombotic genes important in the pathogenesis of chronic disorders as apparently diverse as diabetic macrovascular disease and amyloidosis (10 -20).…”

“…These findings may have direct implications for inflammatory processes that characterize certain complications of diabetes and renal failure, for example, such as atherosclerosis, impaired wound healing, aggressive and inflammatory periodontal disease, and dialysis-related amyloidosis (DRA) (6,(35)(36).…”

Gastrointestinal β2microglobulin amyloidosis in hemodialysis patients: biochemical analysis of amyloid proteins in small formalin-fixed paraffin-embedded tissue specimens

“…36,37 In fact, previous biochemical studies on Ab 2 M proteins were performed using larger amounts of fresh (unfixed) tissues obtained at autopsy 5,8,12 or at carpal tunnel release operations. 4,10 In these studies, the classical amyloid isolation methods, which include the water extraction method of Pras 10,12,38 and the guanidine hydrochloride solubilization technique, 4,5,8 were successfully used, but these methods were found unsuitable for biochemical examination of small fixed biopsy specimens. Recently, we reported a new simple formic acid microextraction technique allowing the recovery and chemical typing of amyloid in small formalin-fixed biopsy specimens.…”

“…4,8 A possibility was raised that in contrast to the normal circulating b 2 M, the deposited Ab 2 M proteins contain some acidic isoforms. [10][11][12] The appearance of these isoforms was explained by deamination of Asn17 13,14 or modification by advanced glycation end products (AGE), 10,12 but these findings have not been confirmed by other authors. 15 In addition, presence of acidic b 2 M isoforms has been demonstrated in normal urine, thus bringing up the question whether these isoforms are specific to dialysis-related amyloidosis.…”

Fever associated with severe dialysis-related amyloidosis

“…Miyata et al [6,7] have reported that advanced glycation end product (AGE)-b 2 M may function as a pathogenic factor responsible for induction of the inflammatory response that ultimately leads to joint/bone destruction in DRA. However, only some reports have documented b 2 M-based induction of the systemic inflammatory response in patients on long-term HD [8,9].…”