Department of Medicine, Division of Gastroenterology, University of Florida, CGRC, 2033 Mowry Rd, Florida, 32610, USA.
Department of Pediatrics, University of Florida, Gainesville, Florida, USA.
BMC Microbiol. 2020 Jul 11;20(1):205. doi: 10.1186/s12866-020-01892-7.
The intestinal tract undergoes a period of cellular maturation during early life, primarily characterized by the organization of epithelial cells into specialized crypt and villus structures. These processes are in part mediated by the acquisition of microbes. Infants delivered at term typically harbor a stable, low diversity microbiota characterized by an overrepresentation of various Bacilli spp., while pre-term infants are colonized by an assortment of bacteria during the first several weeks after delivery. However, the functional effects of these changes on intestinal epithelium homeostasis and maturation remain unclear. To study these effects, human neonate feces were obtained from term and pre-term infants. Fecal 16S rDNA sequencing and global untargeted LC-MS were performed to characterize microbial composition and metabolites from each population. Murine enteral organoids (enteroids) were cultured with 0.22 μm filtered stool supernatant pooled from term or pre-term infants.
Term and pre-term microbial communities differed significantly from each other by principle components analysis (PCoA, PERMANOVA p < 0.001), with the pre-term microbiome characterized by increased OTU diversity (Wilcox test p < 0.01). Term communities were less diverse and dominated by Bacilli (81.54%). Pre-term stools had an increased abundance of vitamins, amino acid derivatives and unconjugated bile acids. Pathway analysis revealed a significant increase in multiple metabolic pathways in pre-term samples mapped to E. coli using the KEGG database related to the fermentation of various amino acids and vitamin biosynthesis. Enteroids cultured with supernatant from pre-term stools proliferated at a higher rate than those cultured with supernatant from term stools (cell viability: 207% vs. 147.7%, p < 0.01), grew larger (area: 81,189μm vs. 41,777μm, p < 0.001), and bud at a higher rate (6.5 vs. 4, p < 0.01). Additionally, genes involved in stem cell proliferation were upregulated in pre-term stool treated enteroid cultures (Lgr5, Ephb2, Ascl2 Sox9) but not term stool treated enteroids.
Our findings indicate that microbial metabolites from the more diverse gut microbiome associated with pre-term infants facilitate stem cell proliferation. Therefore, perturbations of the pre-term microbiota may impair intestinal homeostasis.
肠道在生命早期经历细胞成熟阶段，主要表现为上皮细胞形成专门的隐窝和绒毛结构。这些过程部分受微生物获得的调节。足月出生的婴儿通常携带稳定的低多样性微生物群，其特征是各种芽孢杆菌的过度表达，而早产儿在出生后的头几周内会被各种细菌定植。然而，这些变化对肠道上皮细胞稳态和成熟的功能影响尚不清楚。为了研究这些影响，从足月和早产儿中获得了人类新生儿粪便。进行粪便 16S rDNA 测序和非靶向 LC-MS 以分别从每个群体中鉴定微生物组成和代谢物。用来自足月或早产儿的 0.22μm 过滤粪便上清液培养鼠肠类器官（肠类器官）。
通过主成分分析（PCoA，PERMANOVA p<0.001），足月和早产儿微生物群落彼此之间存在显著差异，早产儿微生物组的 OTU 多样性增加（Wilcox 检验 p<0.01）。足月群落的多样性较低，以芽孢杆菌为主（81.54%）。早产儿粪便中维生素、氨基酸衍生物和未结合胆汁酸的含量增加。途径分析显示，使用 KEGG 数据库映射到大肠杆菌的，早产儿样本中与各种氨基酸发酵和维生素生物合成相关的多个代谢途径显著增加。与用来自足月粪便的上清液培养的肠类器官相比，用来自早产儿粪便的上清液培养的肠类器官增殖速度更快（细胞活力：207%比 147.7%，p<0.01），生长更大（面积：81189μm 比 41777μm，p<0.001），芽生速度更快（6.5 比 4，p<0.01）。此外，与早产儿粪便处理的肠类器官培养物中，参与干细胞增殖的基因上调（Lgr5、Ephb2、Ascl2、Sox9），但在足月粪便处理的肠类器官中没有上调。
我们的研究结果表明，与早产儿相关的多样性更高的肠道微生物群的微生物代谢物促进干细胞增殖。因此，早产儿微生物群的干扰可能会损害肠道稳态。
