Microbiota and mucosal immunity: a balance between symbiosis and defense

There are a large number of microbial communities in the human body, and they form a complex symbiotic relationship with the host. As the main interface between the human body and the external environment, the mucosa is not only the main place for microbial colonization, but also an important barrier for immune defense. Recent studies have shown that there is a close interaction between the microbiota and the mucosal immune system (MIS) to maintain human health. In this review, we will review the interaction mechanism between microecology and MIS from four aspects: pattern recognition receptor recognition, microbial molecular pattern-mediated signaling pathway, microbial metabolites regulation of MIS, microbial maintenance of mucosal barrier function, and feedback regulation of MIS on microecology.