Chitosan lowers body weight through intestinal microbiota and reduces IL-17 expression via mTOR signalling

This study was conducted to explore the effect of chitosan supplementation on mouse intestinal microbiota and interleukin-17 (IL-17) expression. Chitosan supplementation reduced mouse body weight, associating with change of intestinal microbiota (i.e. lowering the ratio of Firmicutes: Bacteroidetes). In antibiotics treated mice, chitosan supplementation had little effect on mouse body weight. Chitosan supplementation decreased expression of IL-17 in mouse jejunum and inhibited the mTOR pathway. In antibiotics treated mice, chitosan also reduced expression of IL-17 in the jejunum. Activation of mTOR signalling in mouse increased expression of IL-17 in the jejunum in the context of chitosan supplementation. We conclude that chitosan supplementation reduces mouse body weight through the intestinal microbiota, and inhibits intestinal IL-17 expression through the mTOR signalling. The discovery of this study suggests the potentials of chitosan as a functional supplement in intestinal health.