Glycated albumin increases oxidative stress, activates NF-kappa B and extracellular signal-regulated kinase (ERK), and stimulates ERK-dependent transforming growth factor-beta 1 production in macrophage RAW cells.
Albumin modified by Amadori glucose adducts has been shown to modulate signal transduction and induce alterations in renal glomerular cells that contribute to the development of diabetic nephropathy. However, the participation of this nonenzymatically glycated protein in the pathobiology of atherosclerotic cardiovascular disease in diabetes has not been established. To probe this issue, we used macrophage RAW cells to assess the effects of glycated albumin on molecular events implicated in the pathogenesis of diabetes-related vascular complications. RAW cells were cultured in medium containing 5.5 mmol/L glucose and glycated or nonglycated albumin, with and without the addition of PD98059, a specific inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK), followed by analysis of phosphorylated ERK and the nuclear translocation of nuclear factor (NF)-kappa B and measurement of cellular content of thiobarbituric acid-reactive substances and the concentration of transforming growth factor (TGF)-beta(1) in the spent medium. We demonstrate, for the first time, that glycated albumin activates RAW cell ERK and promotes ERK-dependent increases in TGF-beta(1) production, oxidative stress, and NF-kappa B activation. Preincubation with the antioxidant alpha-lipoic acid partially prevented the glycated albumin-induced increase in NF-kappa B activation. These findings indicate that Amadori-modified glycated albumin modulates macrophage cell biology independent of high glucose concentration. The effects of glycated albumin on RAW cell molecular mediators and cytokine production may have pathophysiologic significance with respect to the accelerated atherosclerosis that occurs in diabetes.
Cohen
Margo P
MP
Institute of Metabolic Research, University City Science Center, Research University of Pennsylvania, 3508 Market Street, Suite 420, Philadelphia, PA 19104, USA. drmpcohen@aol.com
Shea
Elizabeth
E
Chen
Sheldon
S
Shearman
Clyde W
CW
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002460:Cell Line; D017077:Culture Media, Conditioned / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D017127:Glycation End Products, Advanced; D006031:Glycosylation; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis*; D016328:NF-kappa B / Q000096:biosynthesis*; D018384:Oxidative Stress / Q000187:drug effects*; D012709:Serum Albumin / Q000737:chemistry / Q000494:pharmacology*; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D008063:Thioctic Acid / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis*; D053773:Transforming Growth Factor beta1; D000093423:Glycated Serum Albumin
D000975:Antioxidants; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D005419:Flavonoids; D017127:Glycation End Products, Advanced; D016328:NF-kappa B; D012709:Serum Albumin; C508961:Tgfb1 protein, mouse; D017392:Thiobarbituric Acid Reactive Substances; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D008063:Thioctic Acid; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000093423:Glycated Serum Albumin