P838 Characteristics of mucosal microbial composition of patients with inflammatory bowel disease susceptibility HLA genotype

A. Hirano, J. Umeno, T. Torisu

Kyushu University, Department of Medicine and Clinical Science, Fukuoka, Japan

Background

Although inflammatory bowel diseases (IBD) is presumed to develop as the result of dysregulated immune response to the intestinal microbiota in genetically susceptible hosts, the association between microbiota and genotypes in IBD patients remains unclear. The human leukocyte antigen (HLA)-Cw*1202-B*5201-DRB1*1502 haplotype has been reported to increase the susceptibility to ulcerative colitis (UC), and the HLA-DRB1#37Ser reduce the risk of Crohn’s disease (CD) in East Asian population. We investigated the association between IBD susceptibility HLA genotype and mucosal microbial composition to elucidate the pathogenesis of IBD.

Methods

Mucosal bioptic sampling was performed from the rectum under colonoscopy for the analysis of mucosal microbial composition among 54 IBD patients (27 patients with CD and 27 patients with UC). The mucosal microbial community structure was investigated using 16S rRNA gene sequences, and the structures were analysed using Qiime and LEfSe software. All patients were genotyped using the Affymetrix Japonica Array, and their HLA genotypes were determined by imputation based on the Japanese-specific references.

Results

Twelve CD patients had the HLA-DRB1#37Ser allele and 15 UC patients had the HLA-Cw*1202-B*5201-DRB1*1502 allele. Microbes of family Barnesiellaceae and genus Anaerofilum were more abundant in HLA-DRB1#37Ser allele carriers when compared with non-carriers among CD patients. Among UC patients, decreased abundance of the genus Acidaminococcus and increased abundance of genera Veillonella, SMB53, Lachnospira and Haemophilus was evident in HLA-Cw*1202-B*5201-DRB1*1502 allele carriers when compared with non-carriers.

Conclusion

IBD susceptibility HLA genotype might affect mucosal microbiota composition in both CD and UC.