Host Gut Microbiota-Immune System Axis (Gut-Immune Axis)

The host gut microbiota and immune system constitute a dynamic and bidirectional communication network known as the gut-immune axis. This system involves the interaction between trillions of commensal microorganisms—including bacteria, fungi, and viruses—and the host's innate and adaptive immune components, primarily located within the gut-associated lymphoid tissue (GALT) [Nature Reviews Immunology 2009, 9(5):313-323]. The microbiota plays a critical role in training the immune system, promoting the development of regulatory T cells (Tregs) and maintaining a balance between pro-inflammatory and anti-inflammatory responses through the production of metabolites like short-chain fatty acids (SCFAs) [Science 2013, 341(6145):569-573]. Dysregulation of this axis, often termed dysbiosis, is implicated in a wide range of pathologies, including inflammatory bowel disease (IBD), autoimmune disorders, and metabolic syndrome [NIH/NCBI PMC3448089]. Furthermore, the composition of the gut microbiota has been shown to significantly influence the efficacy of systemic treatments, such as immune checkpoint inhibitors in oncology [Science 2018, 359(6371):97-103]. Therapeutic interventions targeting this axis include probiotics, prebiotics, and fecal microbiota transplantation (FMT), which aim to restore microbial diversity and healthy immune signaling.

Other names

Gut-microbiota-immune axisMicrobiome-immune system crosstalkIntestinal microbiota-immune system interactionGut-microbiota-immune system axis

Interventions modulate the gut-immune axis by altering microbial composition to increase the production of metabolites like butyrate, which signals through G protein-coupled receptors (e.g., GPR43, GPR109A) to induce FOXP3+ regulatory T cells (Tregs) and strengthen the intestinal barrier [Nature 2013, 504(7480):446-450]. Additionally, specific microbial-associated molecular patterns (MAMPs) interact with host pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) and NOD-like receptors (NLRs) to calibrate innate immune sensitivity and maintain epithelial barrier integrity [Nature Reviews Immunology 2009, 9(5):313-323].