Abstract
Background. Recent evidence suggests that the gut microbiota (GM) in Behçet’s syndrome patients (BS) has low diversity and a peculiar layout. Diet is known to influence the GM, but to date no study has investigated its effect on these patients. Aim. To evaluate the effect of a lacto-ovo vegetarian diet (VD) and a Mediterranean diet supplemented with 2 g/die of oral butyrate (MD-Bt) in comparison with a Mediterranean diet (MD) on the GM in BS. Methods. Forty-four (27F; mean age: 46.9 ± 11.2 years) BS patients were randomly assigned to follow a VD, MD-Bt, or MD for 3 months each and then crossed over. Stool samples were collected from the participants at the beginning and at the end of each intervention phase. Samples were analyzed through 16S rRNA amplicon sequencing on an Illumina MiSeq platform. Results. Regarding alpha diversity, a decreasing trend after a VD (Shannon index: p = 0.069; observed species: p = 0.08) and an increasing trend after a MD (Shannon index: p = 0.084; observed species: p = 0.079) were observed. Regarding beta diversity, no significant separation was found between the sample groups either over time or between different interventions. Phylum-level taxonomic analysis showed a significant increase in Bacteroidetes (+2.6%; p = 0.049) following the MD and a significant reduction in Proteobacteria (−0.2%; p = 0.035) following the MD-Bt. At the family level, we observed a significant increase in Bacteroidaceae (+2%; p = 0.05) and Porphyromonadaceae (+0.3%; p = 0.004) after the MD, a significant reduction in Porphyromonadaceae (−0.4%; p = 0.05) and Rikenellaceae (−0.7%; p = 0.03) after the VD, and a significant reduction in Rikenellaceae (−0.2%; p = 0.008) and Turicibacteraceae (−0.02%; p = 0.04) after the MD-Bt. In addition, there was a significant increase in the genus Bacteroides (+2%; p = 0.05) and Parabacteroides (−0.2%; p = 0.004) after the MD. On the other hand, the MD-Bt, led to a significant increase in Clostridium (+1%; p = 0.05) and a significant reduction in Oscillospira (−0.6%; p = 0.011) and Turicibacter (−1.9%; p = 0.04). Conclusions. The MD appeared to have an overall better impact on the GM modulation of BS in terms of higher diversity and potentially beneficial compositional changes.
Author Contributions
Conceptualization, G.P., G.E. and F.S.; methodology, G.P., S.T., G.E. and F.S.; formal analysis, G.P., F.D. and S.T.; investigation, G.P., I.M., M.T.A., G.E. and F.S.; writing—original draft preparation, G.P.; writing—review and editing, S.T., G.E. and F.S.; supervision, F.S. All authors have read and agreed to the published version of the manuscript.
Funding
This study is co-funded by the Italian Ministry of Health (Ricerca Finalizzata 2016; Reference Number: GR-2016-02361162) and by the Tuscany region. The study is also co-funded by a grant from the Associazione Italiana Sindrome e Malattia di Behçet (SIMBA) Onlus. The funders had no input into the design and conduct of the project; collection, management, analysis, and interpret- ation of the data; and preparation, review, or approval of the manuscript.
Institutional Review Board Statement
The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of The Tuscany Region, Careggi University Hospital (protocol code 12773_SPE).
Informed Consent Statement
Informed consent was obtained from all subjects involved in the study.
Data Availability Statement
The data presented in this study are available on request from the corresponding author.
Conflicts of Interest
The authors declare no conflict of interest.
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