Data_Sheet_2_Irradiation-Induced Intestinal Damage Is Recovered by the Indigenous Gut Bacteria Lactobacillus acidophilus.pdf

The intestinal tract is one of the most sensitive organs following irradiation. The protective effect of specific indigenous microbiota on irradiation-induced damage to intestinal epithelial cells has not been reported. Mice were irradiated with a single dose of 6 Gy of gamma rays. The intestinal damage was analyzed by histopathology. Intestinal stemness and differentiation were determined by intestinal organoid culture. Microbiota community was observed by high-throughput 16S rRNA gene sequencing and oligotyping analysis. We showed that distal small intestine was damaged by sublethal dose of gamma irradiation. Intestinal organoids derived from the irradiated mice showed defects in budding and mucin expression, suggesting the detrimental effect of irradiation on the intestinal stemness and differentiation. In addition, irradiation reduced intestinal immunoglobulin A level, concomitant with decreased microbiota diversity based on our high-throughput 16S rRNA gene sequencing data. Especially, the relative abundance of Lactobacillus was reduced at early time point post-irradiation; however, it was recovered at late time point. Oligotyping analysis within the Lactobacillus genus indicated that Lactobacillus-related oligotype 1 (OT1) including Lactobacillus acidophilus might drive recovery after irradiation as it was associated with increased long-term numbers post-exposure. We showed that treatment with heat-killed L. acidophilus rescued the budding-impaired organoids and induced sufficient differentiation in epithelial cells, and particularly mucin-producing cells, in intestinal organoids. This study provides the first evidence that the indigenous gut bacteria L. acidophilus enhance intestinal epithelial function with respect to irradiation-induced intestinal damage by improving intestinal stem cell function and cell differentiation.

肠道是辐照后最为敏感的器官之一。关于特定固有微生物群对肠道上皮细胞辐照损伤的防护作用尚未有报道。实验中，小鼠接受了单次6 Gy伽马射线辐照。通过组织病理学方法分析了肠道损伤。肠道干细胞及其分化能力通过肠道类器官培养进行确定。微生物群社区通过高通量16S rRNA基因测序和寡核苷酸分型分析进行观察。研究发现，远端小肠受到亚致死剂量伽马辐照的损伤。从辐照小鼠中分离出的肠道类器官表现出发芽和粘蛋白表达的缺陷，这表明辐照对肠道干细胞及其分化具有不利影响。此外，辐照降低了肠道免疫球蛋白A的水平，与我们基于高通量16S rRNA基因测序数据获得的微生物群多样性降低的结果相一致。特别是在辐照后的早期时间点，乳杆菌的相对丰度降低；然而，在晚期时间点得以恢复。乳杆菌属内的寡核苷酸分型分析表明，乳杆菌相关寡核苷酸类型1（OT1），包括乳杆菌酸杆菌，可能与辐照后的恢复相关，因为它与暴露后长期数量的增加有关。我们证实，使用热杀死的乳杆菌酸杆菌处理能够挽救发芽受损的类器官，并诱导肠道类器官中上皮细胞，尤其是分泌粘蛋白细胞的充分分化。本研究首次提供了证据，表明固有肠道细菌乳杆菌酸杆菌通过改善肠道干细胞功能和细胞分化，增强了肠道上皮细胞对辐照诱导的肠道损伤的防护作用。