Role of microbiota in radiation-induced small-bowel damage

Radiation-induced gastrointestinal damage is a common acute radiation syndrome. Previous studies have highlighted that Galectin-1 and Interleukin-6 (IL-6) are associated with flaking of small intestinal villi and intestinal radioresistance. Therefore, our goal is to study whether gut bacteria regulated by galectin-1 or IL-6 can mitigate radiation-induced small intestine damage. In this study, differences between galectin-1, sgp130-regulated and wild-type (WT) mice were analyzed by microbiome array. The effects of the Firmicutes/Bacteroidetes (F/B) ratio and the proportion of bacterial distribution at the phylum level were observed after 18 Gy whole abdomen radiation. Fecal microbiota transplantation was used to implant radioresistant gut flora into WT mice, and the number of viable small intestinal crypt foci was observed by immunohistochemistry. Fecal transplantation from galectin-1 knockout and sgp130 transgenic mice, with higher radiation resistance, into WT mice significantly increased the number of surviving small intestinal crypts. This radiation resistance, generated through gene regulation, was not affected by the F/B ratio. We initially found that the small intestinal villi of WT mice receiving radioresistant mouse fecal bacteria demonstrated better repair outcomes after radiation exposure. These results indicate the need for a focus on the identification and application of superior radioresistant bacterial strains. In our laboratory, we will further investigate specific radioresistant bacterial strains to alleviate acute side effects of radiation therapy to improve the patients' immune ability and postoperative quality of life. (author)