Crosstalk between the Immune Receptors and Gut Microbiota

The mucosal surfaces of the intestinal tract are constantly exposed to complex microbial communities that contain commensal microorganisms and potential pathogens. Therefore, hosts harbor multiple molecular mechanisms to modulate the gut innate immunity to achieve gut-microbe homeostasis. Pattern recognition receptors (PRRs), such as Toll-like receptor (TLR) and nucleotide oligomerization domain (NOD)-like receptor (NLR), play a key role in sensing pathogens and promoting the induction of innate effectors. Gut microbiota, through PRRs, can modulate the expression of genes involved in inflammatory responses and the production of antimicrobial peptides. In turn, the expression of PRRs affects the structure of gut microbiota in health or disease status. Deficiency in PRRs such as NOD2 and TLR5 can alter the gut microbiota composition in mice. The crosstalk between PRRs and microbiota connects the microbial action with the host response. This article outlines recent advances in the role of immune sensors in the gut microbiota balance and the related microbiota-host interaction.