Gut microbiota and host immune–barrier systems

"Gut microbiota and host immune–barrier systems" refers not to a single molecule or receptor but to the complex, bidirectional interactions between the trillions of microbes residing in the gastrointestinal tract ("gut microbiota") and the body’s immune and physical barrier systems, especially those of the gut mucosa[1][2][3][4][5]. The gut barrier consists of physical (epithelial cells, mucus), chemical (antimicrobial peptides), and immunological (immune cell populations, secretory IgA) layers[2][4][5]. These systems collectively defend the host from pathogens, regulate tolerance to commensal microbes and dietary antigens, and help maintain homeostasis[2][3][5]. Gut microbes produce metabolites such as short-chain fatty acids that directly affect immune cell function and epithelial health[1][7]. The immune system, in turn, shapes the composition and function of the gut microbiota[3][4]. Disruptions—such as altered microbiota composition (dysbiosis) or barrier impairment—can drive a broad range of diseases from inflammatory bowel disease and infections to metabolic and neurodegenerative disorders[3][4][5]. As a therapeutically defined "target," this concept is imprecise: while drugs such as probiotics, prebiotics, antibiotics, fecal microbiota transplantation, and some dietary interventions are designed to act on this system, there is no single molecular entity, receptor, or well-bounded target called the "gut microbiota and host immune/barrier systems"[1][3][4]. This entry is incorrect as a molecular or receptor "target," since it represents a multi-component physiological and ecological system rather than a defined druggable entity.

Other names

gut microbiome–immune system axisgut-immune axisgut microbiota–immune crosstalkintestinal barrier–microbiota interactions