The intestinal epithelium is a monolayer of polarized columnar cells that act as a border between the host and its environment and are the first line of defence against the luminal microbes. In addition to providing a physical barrier, the epithelium possesses a multitude of active mechanisms to fight invading pathogens and regulate the composition and spatial distribution of commensals. The different epithelial cell types have unique functions in this context, and crosstalk with the immune system further modulates their intricate antimicrobial responses.

The epithelium is organized into clonal crypt units with a high cellular turnover that is driven by stem cells located at the base. There is increasing evidence that this anatomical organization, the stem cell turnover, and the lineage determination processes are essential for barrier maintenance. These processes can be modulated by microbes directly or by the immune responses to enteric pathogens, resulting in a rapid and efficient adaptation of the epithelium to environmental perturbations, injuries, and infections. Here we discuss the complex host-microbial interactions that shape the mucosa and how the epithelium maintains and re-establishes homeostasis after infection.

肠上皮是极化的柱状细胞的单层，其充当宿主与其周围环境之间的边界，并且是对抗腔微生物的第一道防线。除了提供物理屏障外，上皮还具有多种主动机制来抵抗入侵的病原体并调节共生体的组成和空间分布。在这种情况下，不同的上皮细胞类型具有独特的功能，并且与免疫系统的串扰进一步调节了它们复杂的抗菌反应。

上皮被组织成具有高细胞更新率的克隆隐窝单元，其由位于基部的干细胞驱动。越来越多的证据表明这种解剖组织，干细胞更新和谱系确定过程对于屏障的维持至关重要。这些过程可以通过微生物直接调节，也可以通过对肠道病原体的免疫反应来调节，从而使上皮快速有效地适应环境扰动，伤害和感染。在这里，我们讨论了形成粘膜的复杂宿主-微生物相互作用，以及感染后上皮如何维持和重建体内平衡。