Profiling the microbiome of oral and genital mucosal surfaces in Behçet's disease

Almost 90% of Behçet's patients present with oral and/or genital ulcers which influence the disease outcome. We hypothesised that the dysregulation of the oral and genital microbiome, coupled with dysregulation of the immune response, contributes to the aetiopathogenesis of Behçet's Disease (BD) and drives disease activation.

152 BD patient samples; 70 matched oral and genital samples plus 12 unmatched samples (Female: Male, 58:12; mean age, 42 ± 13.9: 39.3 ± 10.3) to profile microbial community high-throughput sequencing of the microbiome using 16 s rRNA sequencing targeting the V1/V2 and V3/V4 hyper variable regions were used and results reviewed in relation to disease severity, Work and Social Adjustment Scale (WSAS) outcomes and medication.

Alpha and beta diversity were significantly decreased in genital compared to oral samples; p value<0.05. However, grouping the samples as to whether ulceration was present was not significant. Escherichia-Shigella was the only Amplicon Sequence Variants (ASVs) in the V1/V2 region that was shared between the oral mucosa with ulcer (O_U) and genital mucosa with ulcer (G_U) groups. This was in contrast to the V3/V4 region which indicated that Lachnospiraceae, Saccharimonadales, and Coriobacteriales were shared between the O_U and G_U groups. In addition, gender had no impact on the bacterial abundance in V1/V2 analysis of the oral and genital samples. V3/V4 analysis of genital samples demonstrated that Lactobacilli and Gardnerella were significantly increased in females (20 times) compared to the males in samples; p-adj <0.05. Interestingly in BD patients, Rothia which is commonly found in the mouth was present in both oral and genital samples. Streptococci were significantly increased while Veillonella significantly decreased in the presence of oral ulceration in the BD cohort. The clinical phenotype had no effect on V1/V2 and V3/V4 on the bacterial abundance of oral samples. However, medication e.g. colchicine had a significant effect on the oral microbial abundance (V1/V2; P = 0.020, V3/V4; P = 0.003). There was no relationship between colchicine and the presence/absence of genital ulcers. BD patients with active disease had higher WSAS scores, and their bacterial abundance differed significantly from the non-active BD patients (ADONIS, R2 = 0.05, p value =0.029).

The presence of the microbes Streptococcus, Veillonella, Gardnerella, Lactobacillus, Atopobium, Peptoniphilus, Corynebacterium and Staphylococcus may provide early evidence of BD patients are with active disease.