IBD patients show an IgG immune response towards specific intestinal bacteria genera.

Roo-Brand, G. (Geesje) (2014) IBD patients show an IgG immune response towards specific intestinal bacteria genera. thesis, Medicine.

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Abstract

The human gut microbiota is an important environmental factor in the pathogenesis of inflammatory bowel disease (IBD). IBD patients have elevated levels of mucosal and serum IgG directed against antigens of intestinal bacteria such as flagellins. The aim of this study is to determine to which bacteria the humoral immune response is reactive in IBD patients. Fecal and serum samples were obtained from 55 IBD patients. The fecal bacteria were incubated with autologous serum and the serum IgG binding bacteria were sorted by Magnetic-Activated Cell Sorting. The enrichment of IgG coated bacteria by this sorting was confirmed by flow cytometry. The bacterial composition of both the enriched samples and the original fecal samples was determined by 16S rRNA-gene profiling using Illumina sequencing. Principal component analysis of the results indicated that the IgG response was directed against typical small intestinal genera such as Streptococcus, Lactobacillus, Lactococcus, Enterococcaceae and Veillonella and also against Enterobacteriaceae and the genera Ruminococcus, Coprococcus and Dorea from Clostridium cluster XIVa. The IgG immune response was not directed against other commensal large intestinal bacteria such as Lachnospiraceae including Roseburia and Blautia, Ruminococcaceae including Faecalibacterium, and Bacteroides. There was no difference in the pattern of enrichment of IgG coated bacteria between patients with ulcerative colitis or Crohn’s disease. Furthermore, there was no correlation with disease activity nor with disease location. In conclusion, these results indicate that there is an IgG immune response towards specific gut bacteria. The role of these bacteria in the pathogenesis of IBD needs to be elucidated.

Item Type:	Thesis (Thesis)
Supervisor name:	Harmsen, dr. H. J. M. and Dijkstra, Prof. dr. G. and Sadabad, M. Sadaghian
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 10:46
Last Modified:	25 Jun 2020 10:46
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/722

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