Effect of gamma irradiation on intestinal system and protective effect of Lactobacillus acidophilus on damaged intestinal epithelial cells

Background: The gastrointestinal tract is one of the most sensitive organs togamma irradiation during radiation therapy. It is important to understand howirradiation affects intestinal components to improve its efficacy for clinicalapplications. We aimed to demonstrate the effect of gamma irradiation on theintestinal composition in a time-dependent manner.Results: Based on analysis by high-throughput 16S rRNA gene sequencing, thediversity of microbiota was substantially decreased after irradiation. Especially, therelative abundance of Lactobacillus was reduced post-irradiation. Further, significantdamage to the intestinal epithelial cell (IEC) layer in the ileum, concomitant with aloss of crypt villus architecture, was observed. Intestinal organoids derived from theirradiated mice showed defects in budding, suggesting the destructive effect ofirradiation on the stemness of intestinal epithelial cells. However, we show here thattreatment with either heat-killed Lactobacillus acidophilus or its outer membranevesicles (OMVs) rescued the budding-impaired phenotype in organoids and inducedsufficient differentiation in epithelial cells, and particularly mucin-producing cells, inintestinal organoids.Conclusions: Our results suggest that indigenous gut bacteria and their OMVs haveprotective effects on irradiation induced damage to epithelial cells.