The gut epithelium serves to maximize the surface for nutrient and fluid uptake, but at the same time must provide a tight barrier to pathogens and remove damaged intestinal epithelial cells (IECs) without jeopardizing barrier integrity. How the epithelium coordinates these tasks remains a question of significant interest. We used imaging and an optical flow analysis pipeline to study the dynamicity of untransformed murine and human intestinal epithelia, cultured atop flexible hydrogel supports. Infection with the pathogen Salmonella Typhimurium (S.Tm) within minutes elicited focal contractions with inward movements of up to ∼1,000 IECs. Genetics approaches and chimeric epithelial monolayers revealed contractions to be triggered by the NAIP/NLRC4 inflammasome, which sensed type-III secretion system and flagellar ligands upon bacterial invasion, converting the local tissue into a contraction epicenter. Execution of the response required swift sublytic Gasdermin D pore formation, ion fluxes, and the propagation of a myosin contraction pulse across the tissue. Importantly, focal contractions preceded, and could be uncoupled from, the death and expulsion of infected IECs. In both two-dimensional monolayers and three-dimensional enteroids, multiple infection-elicited contractions coalesced to produce shrinkage of the epithelium as a whole. Monolayers deficient for Caspase-1(-11) or Gasdermin D failed to elicit focal contractions but were still capable of infected IEC death and expulsion. Strikingly, these monolayers lost their integrity to a markedly higher extent than wild-type counterparts. We propose that prompt NAIP/NLRC4/Caspase-1/Gasdermin D/myosin–dependent contractions allow the epithelium to densify its cell packing in infected regions, thereby preventing tissue disintegration due to the subsequent IEC death and expulsion process.

肠道上皮用于最大限度地吸收营养和液体，但同时必须为病原体提供紧密的屏障，并在不损害屏障完整性的情况下去除受损的肠上皮细胞 (IEC)。上皮如何协调这些任务仍然是一个非常有趣的问题。我们使用成像和光流分析管道来研究在柔性水凝胶支持物上培养的未转化小鼠和人类肠道上皮的动态。感染病原体鼠伤寒沙门氏菌（S.Tm) 在几分钟内引起局灶性收缩，向内运动高达 1,000 IECs。遗传学方法和嵌合上皮单层显示收缩是由 NAIP/NLRC4 炎症小体触发的，它在细菌入侵时感知 III 型分泌系统和鞭毛配体，将局部组织转化为收缩中心。响应的执行需要快速的亚溶解 Gasdermin D 孔形成、离子通量以及肌球蛋白收缩脉冲在整个组织中的传播。重要的是，局灶性收缩先于受感染的 IEC 的死亡和驱逐，并且可能与其脱钩。在二维单层和三维肠体中，多次感染引起的收缩结合在一起，使上皮整体收缩。缺乏 Caspase-1(-11) 或 Gasdermin D 的单层未能引起局灶性收缩，但仍然能够感染 IEC 死亡和驱逐。引人注目的是，与野生型对应物相比，这些单层细胞失去其完整性的程度要高得多。我们建议迅速 NAIP/NLRC4/Caspase-1/Gasdermin D/肌球蛋白依赖性收缩允许上皮细胞在感染区域致密其细胞堆积，从而防止由于随后的 IEC 死亡和排出过程导致的组织分解。