Gut microbiota–mediated tryptophan metabolic dysregulation in the comorbidity of inflammatory bowel disease and autism spectrum disorder: mechanisms and research progress

The “microbiota-gut-brain axis” represents a critical link connecting various aspects of intestinal physiology, brain function, and behavioral performance. Among these, tryptophan metabolism abnormalities mediated by gut microbes through the gut-brain axis (GBA) have garnered widespread attention in the study of IBD-ASD comorbidity. This article reviews the current state of research on tryptophan metabolism abnormalities in IBD-ASD comorbidity, with a particular focus on the connection between peripheral and central tryptophan metabolic derangements mediated by gut microbes via the GBA. Furthermore, we summarize and analyze potential therapeutic targets and intervention strategies in this comorbid condition, integrating recent mechanistic studies and clinical evidence to provide a conceptual framework for understanding the potential mechanisms underlying IBD-ASD comorbidity. However, direct evidence from patients with confirmed IBD-ASD comorbidity remains limited at present, and further clinical studies are still needed to test this hypothesis.