Gut microbiota-immune system axis

The gut microbiota-immune system axis refers to the complex, bidirectional communication network between the trillions of microorganisms in the gastrointestinal tract and the host's innate and adaptive immune systems (Belkaid & Hand, 2014, Science). This axis is essential for the maturation of lymphoid tissues and the maintenance of systemic immune homeostasis, largely mediated by microbial metabolites such as short-chain fatty acids (SCFAs) and secondary bile acids. In a healthy state, the microbiota promotes the differentiation of regulatory T cells (Tregs), preventing aberrant inflammatory responses against commensal bacteria and self-antigens (Round & Mazmanian, 2009, Nature Reviews Immunology). Conversely, dysbiosis—a state of microbial imbalance—is a key driver in the etiology of inflammatory bowel disease (IBD), allergies, and certain autoimmune conditions (Lynch & Pedersen, 2016, NEJM). Therapeutic strategies targeting this axis include fecal microbiota transplantation (FMT), which has shown high efficacy in treating recurrent Clostridioides difficile infections, and the use of probiotics or prebiotics to modulate immune tone. Furthermore, recent research highlights the axis's influence on the efficacy of immune checkpoint inhibitors in oncology, where specific microbial compositions correlate with improved patient outcomes (Gopalakrishnan et al., 2018, Science).

Other names

Fecal microbiota-immune system axisIntestinal microbiome-immune system axisGut-immune axisMicrobiota-immune crosstalkGut microbiota-immune system axis

Modulation of host immune cell populations (e.g., Treg/Th17 balance) through microbial metabolites like short-chain fatty acids (SCFAs), secondary bile acids, and structural components like lipopolysaccharides (LPS) interacting with pattern recognition receptors (PRRs) (Belkaid & Hand, 2014).