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

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.

Research progress on the prevention and treatment of radiation-induced intestinal injury by the genus Lactobacillus / 中华放射肿瘤学杂志

Acute radiation-induced intestinal injury is the common complication in patients following abdominal and pelvic radiotherapy. However, no effective clinical prevention and treatment interventions are available. As the probiotics and symbiotic bacteria, many species of the genus Lactobacillus are normally present in the gastrointestinal tract and beneficial for the intestinal health. Preclinical studies have reported that the genus Lactobacillus can prevent and treat acute radiation-induced intestinal injury by protecting crypt stem cells, maintaining intestinal barrier and exerting the antioxidant effect, etc. Clinical trials have prompted that oral administration of adequate complex probiotics containing Lactobacillus spp.at one week before radiotherapy contributes to preventing radiation-induced diarrhea. In addition, oral intake of the genus Lactobacillus has the tendency to treat radiation-induced diarrhea and mitigate acute radiation proctitis. At present, no relevant adverse events have been reported.