The effect of aspartate supplementation on the microbial composition and innate immunity on mice.

The study was conducted to investigate the changes of intestinal microbiota composition and innate immunity with different dietary dosages of aspartate (Asp) supplementation. Thirty-six female ICR mice were divided randomly to four groups and thereafter fed the basal diets (controls) or those supplemented with additional 0.5, 1.0 and 2.0% aspartate. After 2 week feeding, microbial composition in ileum and feces, gene expression of pro-inflammatory cytokine, and innate immune factors in ileum were determined. The ratio of Firmicutes: Bacteroidetes in ileum and feces decreased in 0.5 and 1.0% Asp-supplemented groups, whereas this ratio increased in feces in 2.0% Asp-supplemented group. Meanwhile, the gene expression of IL-17 and IFN-γ in ileum decreased in 1.0% Asp-supplemented group; the gene expression in ileum of Muc2 decreased in 0.5 and 1.0% Asp-supplemented groups. Dietary supplementation with 2.0% Asp enhanced the expression of pIgR and Crp1 as compared to the other three groups. The results indicated that dietary 1.0% Asp supplementation lowers the ratio of Firmicutes:Bacteroidetes, which affects the innate immunity by decreasing the gene expression of IL-17, IFN-γ, and Muc2 in ileum.