Behçet's Disease Under Microbiotic Surveillance? A Combined Analysis of Two Cohorts of Behçet's Disease Patients

In Behçet's disease (BD), an auto-inflammatory vasculitis, an unbalanced gut microbiota can contribute to pro-inflammatory reactions. In separate studies, distinct pro- and anti-inflammatory bacteria associated with BD have been identified. To establish disease-associated determinants, we performed gut microbiome profiling in BD patients from the Netherlands ( = 19) and Italy ( = 13), matched healthy controls (HC) from the Netherlands ( = 17) and Italy ( = 15) and oral microbiome profiling in Dutch BD patients ( = 18) and HC ( = 15) by 16S rRNA gene sequencing. In addition, we used fecal IgA-SEQ analysis to identify specific IgA coated bacterial taxa in Dutch BD patients ( = 13) and HC ( = 8). In BD stool samples alpha-diversity was conserved, whereas beta-diversity analysis showed no clustering based on disease, but a significant segregation by country of origin. Yet, a significant decrease of unclassified and genera was associated with BD patients compared to HC. Subdivided by country, the Italian cohort displays a significant decrease of unclassified and genera, in the Dutch cohort this decrease is only a trend. Increased IgA-coating of spp., spp. and species was found in stool from BD patients. Moreover, oral Dutch BD microbiome displayed increased abundance of and families. BD patients show decreased fecal abundance of and and increased oral abundance of and . In addition, increased fecal IgA coating of and may reflect retention of anti-inflammatory species and neutralization of pathosymbionts in BD, respectively. Additional studies are warranted to relate intestinal microbes with the significance of ethnicity, diet, medication and response with distinct pro- and inflammatory pathways in BD patients.