Song B.,Zheng C.,Zha C.,Hu S.,Yang X.,Wang L.,Xiao H.
AimsLeucine supplementation promotes intestinal health, but the mechanism is largely unknown. This study aimed to elucidate the mechanisms underlying the beneficial effects of leucine on intestinal homeostasis.Methods and ResultsFemale ICR mice (6‐week‐old) were randomly assigned into three groups: (i) mice received a basal diet; (ii) mice received a dietary 0·5% crystalline l‐leucine supplementation; and (iii) mice received a dietary 1·0% crystalline l‐leucine supplementation. Our results showed that leucine supplementation stimulated the secretion of SIgA in mice ileum and expression of cytokines related to SIgA production. Moreover, leucine supplementation improved the expression of mTOR and p70S6K1 expression. Further study showed that leucine supplementation markedly decreased microbiota richness and induced a shift in the Firmicutes : Bacteroidetes ratio in favour of Firmicutes.ConclusionsTherefore, our data suggested that leucine supplementation could enhance intestinal health through the regulation of mTOR pathway and promoting SIgA secretion in the mouse intestine, which might be associated with intestinal microbiota.Significance and Impact of the StudyThe present study found that dietary leucine supplementation of mice could improve intestinal health by enhancing intestinal SIgA secretion via a nonexclusive mechanism, which might include T cell‐dependent pathway, T cell‐independent pathway and gut microbiota.
This study was aimed at investigating the immunomodulating activity of Hericium erinaceus polysaccharide (HEP) in mice, by assessing splenic lymphocyte proliferation (cell-mediated immunity), serum hemolysin levels (humoral immunity), phagocytic capacity of peritoneal cavity phagocytes (macrophage phagocytosis), and NK cell activity. ELISA of immunoglobulin A (SIgA) in the lamina propria, and western blotting of small intestinal proteins were also performed to gain insight into the mechanism by which HEP affects the intestinal immune system. Here, we report that HEP improves immune function by functionally enhancing cell-mediated and humoral immunity, macrophage phagocytosis, and NK cell activity. In addition, HEP was found to upregulate the secretion of SIgA and activate the MAPK and AKT cellular signaling pathways in the intestine. In conclusion, all these results allow us to postulate that the immunomodulatory effects of HEP are most likely attributed to the effective regulation of intestinal mucosal immune activity.
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