Altered glycosylation of α1-acid glycoprotein in patients with inflammation and diabetes mellitus

Background: In certain pathophysiological conditions, such as inflammation rheumatoid arthritis and diabetes mellitus (DM), alterations in asparagine-linked glycan (N-glycan) patterns of the acute-phase protein, alpha(1)-acid glycoprotein (AGP), have been reported. In this study, we investigated N-glycan structures of AGP purified from the sera of patients with acute inflammation (n = 5), type 2 diabetes mellitus (n = 5), and healthy individuals (n = 5). Methods: N-Glycans were released with peptide N-glycosidase F (PNGase F) from denatured AGP and purified with cellulose cartridge. N-glycans were analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS) in combination with exoglycosidase digestion. Results: We revealed increases in bi-antennary complex glycans and in alpha1-3 fucosylated bi-, tri-, and tetra-antennary glycans and a decrease in tri-antennary glycans in inflammation patients. These results support increases in bindings to concanavalin A (ConA) and Aleuria aurantia lectins (AALs). In diabetic patients, the pathogenesis-specific change in N-glycan patterns of AGP was not significant. Conclusions: The MALDI-TOFMS method is sensitive and suitable for profiling analysis of N-glycans in clinical samples. (C) 2003 Elsevier Science B.V. All rights reserved.