Histological study of diurnal changes in bacterial settlement in the rat alimentary tract
Histological study of diurnal changes in bacterial settlement in the rat alimentary tract
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DOI：
10.1007/s00441-022-03626-9
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发表时间：
2022-04
影响因子：
3.6
通讯作者：
N. Sakata;Y. Mantani;Satoki Nakanishi;Rinako Morishita;T. Yokoyama;N. Hoshi
中科院分区：
文献类型：
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作者：
N. Sakata;Y. Mantani;Satoki Nakanishi;Rinako Morishita;T. Yokoyama;N. Hoshi
据报道，粪便细菌的成分在一天中会发生变化，而定居在上皮细胞上的本土细菌的昼夜节律却大多未知。本研究旨在通过组织学分析阐明大鼠消化道中本土细菌定居的昼夜变化。在食道、胃非腺体区域和回肠中观察到本地细菌全天在粘膜上皮上的沉降以及沉降水平的日变化。沉降层的时间（ZT）峰值因段而异：食道中的ZT 12，胃的非腺体区域中的ZT 6，回肠中的ZT 0。此外，使用组织切片进行的 16S rRNA 扩增子测序表明，ZT 之间回肠中的本土细菌的组成有所不同。在回肠的绒毛间隙中，粘液层（宿主对细菌最基本的防御之一）的形成水平在 ZT 0 时最低。在 ZT 0 时，细菌优先邻近绒毛上皮，而没有被粘液层覆盖的区域。这些发现共同表明，各个部分的沉降水平和可能的本土细菌的组成在白天发生变化。 消化道的结构和粘液层的形成可能最有可能导致本土细菌的这种昼夜变化，至少在回肠中是这样。
The composition of fecal bacteria is reported to change throughout the day, whereas the circadian rhythmicity of indigenous bacteria that settle on the epithelium is mostly unknown. The present study aimed to clarify the diurnal changes in the settlement of indigenous bacteria in the rat alimentary tract using histological analysis. The settlement of indigenous bacteria on the mucosal epithelium throughout the day and the diurnal changes in settlement levels were observed in the esophagus, the nonglandular area of the stomach, and the ileum. The peak of zeitgeber time (ZT) in the settlement level differed by segment: ZT 12 in the esophagus, ZT 6 in the nonglandular area of the stomach, and ZT 0 in the ileum. Moreover, 16S rRNA amplicon sequencing using tissue sections revealed that the compositions of the indigenous bacteria in the ileum differed among ZT. In the intervillous spaces of the ileum, the formation level of the mucus layer, one of the most fundamental host defenses against bacteria, was lowest at ZT 0. Bacteria were preferentially adjacent to the villous epithelium in the area without coverage by the mucus layer at ZT 0. These findings collectively suggest that the settlement level and possibly the composition of the indigenous bacteria changed diurnally in various segments of the alimentary tract, and the formation of the mucus layer might be the most likely to lead to such diurnal changes in indigenous bacteria, at least in the ileum.