Effect of probiotics for regulation of inflammatory response in radiation-induced enteritis

Abstract Purpose: The purpose of this study was to investigate the role of probiotics in radiation enteritis using in vivo mice. Methods: A total of 40 mice were randomly assigned to four groups: control, probiotics, radiotherapy (RT), and RT + probiotics. For the group of probiotics, 0.2 mL of solution that contained 1.0 × 10 8 colony-forming units (CFU) of Lactobacillus rhamnosus GG (LGG) was used and orally administered daily until sacrifice. For RT, a single dose of 14 Gy was administered using a 6 mega-voltage photon beam to the abdominopelvic area. Mice were sacrifice at day 4 (S1) and day 7 (S2) after RT. Their jejunum, colon, and stool were collected. A multiplex cytokine assay and 16s ribosomal RNA amplicon sequencing were then performed. Results : Regarding cytokine concentrations in tissues, pro-inflammatory cytokines TNF, IL-6, and MCP-1 showed decreased protein levels in colon tissues of the RT + probiotics group than in the RT group. The abundance of microbes showed no significant difference between RT + probiotics and RT groups except increased alpha-diversity in the stool at S2 of the RT + probiotics group. Probiotics-related and anti-inflammation-related microbes were dominant in the jejunum, colon, and stool from early days after administration of probiotics (probiotics or RT + probiotics groups). Differentially predicted metabolic pathways associated with anti-inflammatory process were found in the RT + probiotics group compared to the RT alone group. Conclusion : Protective effects of probiotics on radiation enteritis were potentially derived from dominant anti-inflammation-related microbes and metabolites.