Alterations in the taxanomic and predicted functional profile of gut microbiota in Behçet’s Disease

Abstract

Purpose : Behçet's Disease (BD) is a devastating inflammatory condition of unknown cause. Gut microbiome is important in the modulation of the immune system. Therefore, we aim to investigate the phylogenetic and predicted functional compositions of the gut microbiome in patients with BD compared to disease and healthy controls.

Methods : Faecal samples were collected from patients with BD fulfilling the Behçet’s Syndrome International Study Group criteria, along with age- and gender-matched disease and healthy controls. Mucous membrane pemphigoid (MMP) was used as disease control as it has similar systemic mucocutaneous involvement to BD. The V4 region of the 16S rRNA gene of bacterial DNA was amplified and sequenced on Illumina MiSeq. Microbial taxa and metagenomic function (KEGG orthologues) was analysed using Quantitative Insights Into Microbial Ecology (QIIME) and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) software.

Results : A total of 109 participants [BD (n= 47), MMP (n=30), HC (n=32)] were recruited to the study.
The dominant phyla across all three groups were Firmicutes and Bacteroides, followed by Actinobacteria. There was no significantGut difference in the alpha diversity across the groups. Patients with BD had significantly lower relative abundance of Alphaproteobacteria (p=0.016), and higher relative abundance of Tenericutes (p=0.02) compared to disease and healthy controls. Predicted functional metagenome revealed higher relative abundance of microbial genes related to the RIG-1-like receptor signalling pathway (p=0.018), which is important in RNA viral pathogen sensing and initiation of the innate immunity, and lower relative abundance of genes associated with the nucleotide-binding oligomerization domain-like (NOD-like) receptors in patients with BD. Patients who were on immunosuppression had higher relative abundances of microbial genes regulating nucleotide excision repair.

Conclusions : Gut microbiome was altered in patients with BD and was associated with predicted microbial genes regulating the innate immunity.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.