[Efficacy and safety of metformin for Behcet's disease and its effect on Treg/Th17 balance: a single-blinded, before-after study].

OBJECTIVE: Behcet's disease (BD) is an autoimmune disorder that causes most commonly mouth and genital ulcerations and erythema nodules of the skin and currently has limited options of therapeutic medicines. Metformin is recently reported to suppress immune reaction, and we hypothesized that metformin could be an option for treatment of BD. METHODS: Thirty patients with BD were enrolled in this perspective single-blinded, before-after study. We recorded the changes in the mucocutaneous activity index for BD (MAIBD), relapse frequency, C-reactive protein (CRP) level and erythrocyte sedimentation rate (ESR) after metformin treatment to assess the changes in the disease activity. We also analyzed the changes in the protein and mRNA expression levels of Foxp3, interleukin-35 (IL-35), transforming growth factor-beta (TGF-beta), Ror-gammat, IL-17, and tumor necrosis factor-alpha (TNF-alpha) in these patients using ELISA and qRT-PCR. RESULTS: Of the 30 patients enrolled, 26 completed the trial. After the treatment, favorable responses were achieved in 88.46% (23/26) of the patients, and partial remission was obtained in 11.54% (4/26) of them. During the treatment, 8 patients complained of gastrointestinal side effects, for which 4 chose to withdraw from the study in the first week. Our results showed that metformin treatment decreased MAIBD and relapse frequency in the patients, and significantly lowered the clinical inflammatory indexes including CRP and ESR. The results of ELISA and qRT-PCR revealed that metformin treatment obviously increased Foxp3 and TGF-beta expressions at both the protein and mRNA levels and significantly decreased the levels of ROR-gammat, IL-17 and TNF-alpha as well as IL-35 level in these patients. CONCLUSION: Metformin treatment relieves the clinical symptoms, reduces the inflammatory reaction indexes and regulates the Treg/Th17 axis in patients with BD, suggesting the potential of metformin as a candidate medicine for treatment of BD.