Neomangiferin modulates the Th17/Treg balance and ameliorates colitis in mice.

BACKGROUND: Anemarrhena asphodeloides (Liliaceae family) and Mangifera indica L. (Anacardiaceae family) contain neomangiferin as the main active constituent and have been used to treat inflammation, asthma, and pain.

PURPOSE: A preliminary study found that neomangiferin inhibited splenic T cell differentiation into Th17 cells and promoted Treg cell production in vitro. Therefore, we examined its anti-colitic effects in vitro and in vivo.

METHODS: Splenocytes isolated from C57BL/6J mice were treated with neomangiferin. Colitis was either induced in vivo by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) to C57BL/6J mice or occurred spontaneously in colitis caused by interleukin (IL)-10 knockout at age of 13 weeks. Mice were treated daily with neomangiferin or sulfasalazine. Inflammatory markers, cytokines, enzymes and transcription factors were measured by enzyme-linked immunosorbent assay, immunoblot, and flow cytometry.

RESULTS: Neomangiferin suppressed retinoic acid receptor-related orphan receptor gamma t (RORγt) and IL-17 expression in IL-6/transforming growth factor β-stimulated Th17 splenocytes and increased IL-10 expression in vitro. Mouse TNBS-induced colon shortening, macroscopic score, and myeloperoxidase activity were inhibited by neomangiferin, which also reduced TNBS-induced activation of nuclear factor-κB and extracellular signal-regulated kinases, as well as expression of inducible nitric oxide synthase and cyclooxygenase-2. In addition, neomangiferin inhibited TNBS-induced expression of tumor necrosis factor-α, IL-17, IL-6, and IL-1β, and increased IL-10 expression. Neomangiferin inhibited TNBS-induced differentiation to Th17 cells and promoted the development of Treg cells. Moreover, in IL-10(-/-) mice, neomangiferin inhibited colonic myeloperoxidase activity, suppressed Th17 cell differentiation, and reduced levels of TNF-α and IL-17.

CONCLUSION: Neomangiferin may restore the balance between Th17/Treg cells by suppressing IL-17 and RORγt expression and inducing IL-10 and forkhead box P3 expression, thus ameliorating colitis.