Mushroom Bulgaria inquinans Modulates Host Immunological Response and Gut Microbiota in Mice

Abstract

We aimed to determine the prebiotic impact of Mushroom <i>Bulgaria inquinans</i> (BI) on the host immune response and gut microbiota. Male C57BL/6 mice were fed a diet supplemented with 0, 1, or 2% BI for 4 wks. Compared to mice fed with a control diet (0% BI), mice fed with 1 or 2% BI had an increase of T cell proliferation from the spleen, but such change was not found between 1 and 2% BI treated mice. Also, BI at 2% increased the production of IL-2 of splenocytes stimulated with T-cell mitogens, but BI at 1 and 2% did not affect productions of other splenic-T cell cytokines including IL-4, IL-10, and IFN-γ. Interestingly, BI at 1 or 2% inhibited T cell proliferation of mesenteric lymph node (mLN) but this effect was not found between 1 and 2% BI treated mice. Furthermore, BI inhibited the production of IL-2 in anti-CD3/CD28-stimulated T cells from mLN in a dose-dependent manner. Meanwhile, BI at 2%, not 1% inhibited the production of IL-4, IL-10, and IFN-γ of mLN. Since BI at 2% produced a more significant effect on the immune response, we further used BI at 2% to evaluate the effect of BI on gut microbiota. Of note, BI reduced the diversity of gut microbiota and resulted in an increase of <i>Faecalibaculum</i> and <i>Parabacteroides</i> abundance and the decrease of <i>Allobaculum, Candidatus</i>_<i>Saccharimonas</i>, and <i>Rikenella</i> abundance at the genus level. Finally, the correlation was observed between specific bacteria genera and the productions of T-cell cytokines from mesenteric lymphocytes: <i>Rikenella</i> and <i>Candidatus_Saccharimonas</i> correlated positively with IL-2, IL-4, IL-10, and IFN-γ; <i>Bacteroides</i> and <i>Parabacteroides</i> correlated negatively with IL-2 and IL-4; <i>Faecalibaculum</i> correlated negatively with IFN-γ and IL-4 and <i>Bacteroides</i> and <i>Bifidobacterium</i> correlated negatively with IFN-γ. The specific role of each intestinal microbiota observed is still unclear, but BI might exert a prebiotic effect on gut microbiota by increasing the abundance of potentially beneficial bacteria (<i>Faecalibaculum</i>). This is helpful for further demonstrating the healthy-promotion mechanism of <i>B. inquinans</i>.