Background and aims: Patients with inflammatory bowel disease (IBD) share several immunologic similarities with rheumatoid arthritis (RA). Patients with RA have significantly increased levels of serum agalactosyl immunoglobulin G (IgG). Our aim was to investigate the clinical significance of analyzing the oligosaccharide structure of serum IgG in patients with IBD.
Methods: Serum IgG oligosaccharide structures were analyzed using high-performance liquid chromatography in 60 patients with Crohn's disease (CD), 58 patients with ulcerative colitis (UC), 27 healthy volunteers (HV), and 15 disease controls (DC). The activity and mRNA level of beta-1,4-galactosyltransferase (Beta4GalT) in antibody-secreting cells were investigated in these subjects.
Results: The agalactosyl fraction of the fucosylated IgG oligosaccharides (G0F/G2F) in CD and UC was significantly greater than that in HV and DC (P < 0.001). The percentage of subjects with a high G0F/G2F in CD, UC, HV, and DC was 72%, 33%, 0%, and 0%, respectively. G0F/G2F, which is significantly correlated with disease severity in both CD and UC, had higher sensitivity to diagnose IBD compared with anti-Saccharomyces cerevisiae antibody. Moreover, G0F/G2F was significantly correlated with the prognosis of UC patients: patients with a high G0F/G2F did not maintain long-term remission. The activity and mRNA level of Beta4GalT were significantly elevated in UC but not in CD.
Conclusions: G0F/G2F is a potentially effective diagnostic marker of disease activity in both CD and UC, and of the clinical course in UC. A pathophysiologic difference between CD and UC was also demonstrated.