Research progress on tryptophan metabolism involved by gut microbiota in the diagnosis and treatment of acute radiation-induced intestinal injury / 中华放射肿瘤学杂志

ABSTRACT

Gut microbiota not only affects the activity of tryptophan metabolism rate limiting enzymes in intestinal cells, but also cooperatively produces a variety of catalytic enzymes, which directly affects the type and quantity of tryptophan metabolites in the intestine. Multiple tryptophan-associated indole compounds originating from the gut microbiome are significantly decreased in the peripheral blood of mice, and negatively correlated with radiation dose ranging from 2 to 10.4 Gy, which might be biomarkers for acute radiation-induced intestinal injury. Recent studies have reported that indole 3-propionic acid (IPA), indole-3-carboxaldehyde (I3A) and kynurenic acid (KYNA), which are tryptophan catabolites derived from gut microbiota, aryl hydrocarbon receptor, which is one of the receptors for tryptophan catabolites, and inhibition of indoleamine 2,3 dioxygenase-1, which is a main rate-limiting enzyme in intestinal tryptophan catabolism, can protect against radiation-induced intestinal toxicity. A more comprehensive understanding of the dynamics of tryptophan catabolites and their roles in acute radiation-induced intestinal injury is needed to deepen the understanding of the pathogenesis in radiation-induced intestinal injury and exploration of effective diagnostic and therapeutic approaches.