Biotherapeutic potential of gut microbiota-derived indole-3-acetic acid

The gut microbiota produces a variety of metabolites that are crucial for regulating host health and physiological homeostasis. Indole-3-acetic acid (IAA), a microbial metabolite of tryptophan, exhibits diverse biological activities including anti-inflammatory, anti-tumor, anti-obesity, hepatoprotective, enteroprotective, and neuromodulatory effects. Accumulating evidence has demonstrated its therapeutic potential against metabolic, inflammatory, and neurological disorders. Emerging evidence suggests that IAA exerts beneficial effects on mammalian health through multiple mechanisms, including modulation of gut microbiota composition, enhancement of intestinal barrier integrity, immune regulation, attenuation of bone loss, and improvement of glucose and lipid homeostasis. This review systematically summarizes current knowledge regarding IAA sources, elucidates recent advances in understanding its biological functions, and integrates existing evidence on its mechanisms of action in mammalian systems. Collectively, this synthesis provides a framework for future investigations and translational applications of IAA.