title: New insights into deleterious impacts of in vivo glycation on albumin antioxidant activities.
abstract: BACKGROUND
  Albumin constitutes the most abundant circulating antioxidant and prevents oxidative damages. However, in diabetes, this plasmatic protein is exposed to several oxidative modifications, which impact on albumin antioxidant properties.
  
  
  METHODS
  Most studies dealing on albumin antioxidant activities were conducted on in vitro modified protein. Here we tried to decipher whether reduced antioxidant properties of albumin could be evidenced in vivo. For this, we compared the antioxidant properties of albumin purified from diabetic patients to in vitro models of glycated albumin.
  
  
  RESULTS
  Both in vivo and in vitro glycated albumins displayed impaired antioxidant activities in the free radical-induced hemolysis test. Surprisingly, the ORAC method (Oxygen Radical Antioxidant Capacity) showed an enhanced antioxidant activity for glycated albumin. Faced with this paradox, we investigated antioxidant and anti-inflammatory activities of our albumin preparations on cultured cells (macrophages and adipocytes). Reduced cellular metabolism and enhanced intracellular oxidative stress were measured in cells treated with albumin from diabetics. NF-kB -mediated gene induction was higher in macrophages treated with both type of glycated albumin compared with cells treated with native albumin. Anti inflammatory activity of native albumin is significantly impaired after in vitro glycation and albumin purified from diabetics significantly enhanced IL6 secretion by adipocytes. Expression of receptor for advanced glycation products is significantly enhanced in glycated albumin-treated cells.
  
  
  CONCLUSIONS
  Our results bring new evidences on the deleterious impairments of albumin important functions after glycation and emphasize the importance of in vivo model of glycation in studies relied to diabetes pathology.
authors: Université de La Réunion, Plateforme CYROI, Saint Denis de La Réunion, France.
authors: Jennifer
authors: J
authors: Baraka-Vidot
authors: Alexis
authors: A
authors: Guerin-Dubourg
authors: Fanny
authors: F
authors: Dubois
authors: Bertrand
authors: B
authors: Payet
authors: Emmanuel
authors: E
authors: Bourdon
authors: Philippe
authors: P
authors: Rondeau
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D045744:Cell Line, Tumor; D003920:Diabetes Mellitus / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism; D018384:Oxidative Stress; D011499:Protein Processing, Post-Translational; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000096:biosynthesis; D012709:Serum Albumin / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D016328:NF-kappa B; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D012709:Serum Albumin