Increased outer arm and core fucose residues on the N-glycans of mutated alpha-1 antitrypsin protein from alpha-1 antitrypsin deficient individuals

J Proteome Res. 2014 Feb 7;13(2):596-605. doi: 10.1021/pr400752t. Epub 2013 Dec 13.

Abstract

Alpha-1 antitrypsin (AAT) is the major physiological inhibitor of a range of serine proteases, and in the lung, it maintains a protease-antiprotease balance. AAT deficiency (AATD) is an autosomal co-dominant condition with the Z mutation being the most common cause. Individuals homozygous for Z (PiZZ) have low levels of circulating mutant Z-AAT protein leading to premature emphysematous lung disease. Extensive glycoanalysis has been performed on normal AAT (M-AAT) from healthy individuals and the importance of glycosylation in affecting the immune modulatory roles of AAT is documented. However, no glycoanalysis has been carried out on Z-AAT from deficient individuals to date. In this study, we investigate whether the glycans present on Z-AAT differ to those found on M-AAT from healthy controls. Plasma AAT was purified from 10 individuals: 5 AATD donors with the PiZZ phenotype and 5 PiMM healthy controls. Glycoanalysis was performed employing N-glycan release, exoglycosidase digestion and UPLC analysis. No difference in branched glycans was identified between AATD and healthy controls. However, a significant increase in both outer arm (α1-3) (p = 0.04) and core (α1-6) fucosylated glycans (p < 0.0001) was found on Z-AAT compared to M-AAT. This study has identified increased fucosylation on N-glycans of Z-AAT indicative of ongoing inflammation in AATD individuals with implications for early therapeutic intervention.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Case-Control Studies
  • Chromatography, Liquid
  • Electrophoresis, Gel, Two-Dimensional
  • Fucose / metabolism*
  • Humans
  • Male
  • Middle Aged
  • Mutation*
  • Polysaccharides / chemistry
  • Polysaccharides / metabolism*
  • Spectrometry, Fluorescence
  • Tandem Mass Spectrometry
  • Young Adult
  • alpha 1-Antitrypsin / genetics
  • alpha 1-Antitrypsin / metabolism*
  • alpha 1-Antitrypsin Deficiency / metabolism*

Substances

  • Polysaccharides
  • alpha 1-Antitrypsin
  • Fucose