Human intestinal microbiota-host immune system axis (Gut-immune axis)

The human intestinal microbiota-host immune system axis represents the complex, bidirectional communication network between the trillions of microorganisms inhabiting the gastrointestinal tract and the host's mucosal immune system. This ecosystem is fundamental to human health, as the microbiota provides essential signals for the maturation of immune cells, such as regulatory T cells (Tregs) and Th17 cells, primarily through the production of metabolites like short-chain fatty acids (SCFAs) (Belkaid & Hand, 2014, Science). In return, the host immune system maintains the balance of this microbial community through the secretion of antimicrobial peptides and secretory IgA, preventing the overgrowth of opportunistic pathogens (Koh et al., 2016, Cell). Dysbiosis, or the disruption of this delicate balance, is implicated in a wide range of pathologies, including inflammatory bowel disease (IBD), metabolic syndrome, and autoimmune disorders (Ni et al., 2017, Nature Reviews Gastroenterology & Hepatology). Therapeutic interventions targeting this axis, such as live biotherapeutic products (LBPs) and fecal microbiota transplantation (FMT), aim to restore microbial diversity and normalize immune responses. While the FDA has recently approved the first microbiota-based therapies for recurrent Clostridioides difficile infection, such as Vowst and Rebyota, the field faces ongoing challenges regarding the standardization of these complex biological products and the potential for unintended systemic immune effects (FDA, 2023).

Other names

Gut microbiota-immune system axisIntestinal microbiome-immune system interactionMicrobiota-host immunity crosstalkGut-immune system ecosystem

Restoration of microbial diversity and modulation of host immune signaling through microbial metabolites (e.g., SCFAs) and direct cell-to-cell interactions with mucosal immune cells.