Department of Basic Sciences, Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel.
Department of Obstetrics and Gynecology, Hadassah University Hospital, Jerusalem, Israel.
PLoS One. 2021 May 3;16(5):e0243010. doi: 10.1371/journal.pone.0243010. eCollection 2021.
The single-epithelial cell layer of the gut mucosa serves as an essential barrier between the host and luminal microflora and plays a major role in innate immunity against invading pathogens. Nuclear factor kB (NF-κB), a central component of the cellular signaling machinery, regulates immune response and inflammation. NF-κB proteins are activated by signaling pathways downstream to microbial recognition receptors and cytokines receptors. Highly regulated NF-κB activity in intestinal epithelial cells (IEC) is essential for normal gut homeostasis; dysregulated activity has been linked to a number of disease states, including inflammatory bowel diseases (IBD) such as Crohn's Disease (CD). Our aim was to visualize and quantify spatial and temporal dynamics of NF-κB activity in steady state and inflamed human gut. Lentivirus technology was used to transduce the IEC of human gut xenografts in SCID mice with a NF-κB luminescence reporter system. NF-κB signaling was visualized and quantified using low resolution, intravital imaging of the whole body and high resolution, immunofluorescence microscopic imaging of the tissues. We show that NF-κB is activated in select subset of IEC with low "leaky" NF-κB activity. These unique inflammatory epithelial cells are clustered in the gut into discrete hotspots of NF-κB activity that are visible in steady state and selectively activated by systemic LPS and human TNFα or luminal bacteria. The presence of inflammatory hotspots in the normal and inflamed gut might explain the patchy mucosal lesions characterizing CD and thus could have important implications for diagnosis and therapy.
肠道黏膜的单层上皮细胞作为宿主与腔微生物之间的重要屏障，在先天免疫抵抗入侵病原体方面发挥着主要作用。核因子 kB（NF-κB）是细胞信号转导机制的核心组成部分，调节免疫反应和炎症。NF-κB 蛋白通过微生物识别受体和细胞因子受体的下游信号通路被激活。肠道上皮细胞（IEC）中高度调控的 NF-κB 活性对于正常的肠道稳态至关重要；失调的活性与许多疾病状态有关，包括炎症性肠病（IBD），如克罗恩病（CD）。我们的目的是可视化和定量稳态和炎症状态下人类肠道中 NF-κB 活性的时空动态。慢病毒技术用于转导 SCID 小鼠中的人肠道异种移植物的 IEC，使其带有 NF-κB 发光报告系统。使用全身低分辨率、活体成像和组织高分辨率、免疫荧光显微镜成像来可视化和定量 NF-κB 信号。我们表明，NF-κB 在具有低“渗漏”NF-κB 活性的特定 IEC 亚群中被激活。这些独特的炎症上皮细胞在肠道中聚集形成离散的 NF-κB 活性热点，在稳态下可见，并可被全身 LPS 和人 TNFα 或腔细菌选择性激活。正常和炎症肠道中炎症热点的存在可能解释了 CD 特征性的斑片状黏膜病变，因此对诊断和治疗具有重要意义。
