Behcet's syndrome patients exhibit specific microbiome signature

Background and aims: Behcet syndrome is a systemic inflammatory condition characterized by muco-cutaneous and ocular manifestations, with central nervous system, vascular and/or gastro-intestinal involvement. The association of microbiota with Behcet syndrome has not been shown yet. Our work was aimed to compare the gut microbiota structure and the profiles of short-chain fatty acids production in Behcet syndrome patients and healthy control relatives. Methods: Here, we compared the fecal microbiota of 22 patients with Behcet syndrome and that of 16 healthy cohabiting controls, sharing the same diet and lifestyle by pyrosequencing of the V3-V4 hypervariable regions of the 16 rDNA gene and biochemical analyses. Results: Our analyses showed significant differences in gut microbiota between Behcet patients and healthy cohabitants. In particular we found that Behcet's patients were significantly depleted in the genera Roseburia and Subdoligranulum. Roseburia showed a relative abundance value of 10.45 +/- 6.01% in healthy relatives and 4.97 +/- 5.09% in Behcet's patients, and Subdoligranulum, which reached a relative abundance of 3.28 +/- 2.20% in healthy controls, was only at 1.93 +/- 1.75% of abundance in Behcet's patients. Here we report, for the first time, that a peculiar dysbiosis of the gut microbiota is present in patients with Behcet syndrome and this corresponds to specific changes in microbiome profile. A significant decrease of butyrate production (P = 0.0033) in Behcet's patients was demonstrated. Butyrate is able to promote differentiation of T-regulatory cells, and consequently the results obtained prompt us to speculate that a defect of butyrate production might lead to both reduced Treg responses and activation of immuno-pathological T-effector responses. Conclusions: Altogether, our results indicate that both a peculiar dysbiosis of the gut microbiota and a significant decrease of butyrate production are present in patients with Behcet syndrome. Published by Elsevier B.V.