Research progress on the mechanism of functional activity of edible fungi polysaccharides—focusing intestinal mucus as a key and entry point

Edible fungi polysaccharide is a kind of natural active substance, which plays an important role in immune regulation. The research on the mechanism of polysaccharide activity in the early stage mainly focused on the direct action mechanism between polysaccharide and cell, and the indirect action mechanism between polysaccharide and microbe and cell. It mainly focused on the enhancement of immune cells and the regulation of immune active factors, as well as the regulation of intestinal microenvironment homeostasis. Due to the complexity of the intestinal environment, polysaccharides need to interact with the mucous layer of the intestinal tract before entering the intestinal tract to play the function of immune activity. This interaction will change the structure, viscosity and dispersion of polysaccharides, thus affecting the activity of polysaccharides in the body. Therefore, the interaction between polysaccharide and mucus layer is also extremely important. Edible fungi polysaccharides can supplement mucinoglycan to change the glycosylation level of mucin, and also affect the abundance of mucin symbiotic flora, thus changing the secretion of mucin. As prebiotics, the short-chain fatty acids produced by polysaccharides can not only directly act on intestinal epithelial cells, but also maintain energy generation. It can also stimulate goblet cells and maintain mucus barrier homeostasis. The effect of the interaction between polysaccharide and intestinal mucus on intestinal immune activity can be a new direction to study the mechanism of polysaccharide activity.