Defining receptor-ligand interactions in gastric epithelial immunosurveillance

摘要 胃部感染幽门螺杆菌是发病率和死亡率的重要原因，导致慢性 胃炎、消化性溃疡和胃癌。虽然大量的研究工作致力于 研究幽门螺杆菌诱导的胃部炎症的发病机制，其特异性的免疫机制 对胃粘膜的认识还不是很清楚。重要的是，单核巨噬细胞(MNPs)是如何 胃接触幽门螺杆菌对T细胞反应的刺激和调节尚不清楚。 与肠道不同的是，胃缺乏专门用于将抗原从肠腔运送到肠道的M细胞 固有层。然而，很大一部分胃MNPs位于与胃直接接触的位置。 上皮层，可能支持包括跨上皮树突状细胞在内的有效的上皮免疫监视 由MNPs形成。控制这些具有重要功能的粘合剂的受体和配体 胃上皮细胞与MNPs之间的相互作用尚不清楚。在初步研究中，我们有 上皮细胞上表达的E-钙粘附素(E-cad)与E-cad的同型相互作用 由一组胃MNPs表达作为MNP与胃结合的潜在候选机制 上皮组织。目前建议的首要目标是确定受体-配体(R-L)的相互作用 胃中的mNPs用于粘附胃上皮细胞，并确定这些细胞的功能结果。 胃免疫的相互作用。在具体目标1中，我们将确定E-cad介导的MNP- 幽门螺杆菌感染中上皮细胞参与MNP功能的研究为了达到这一目的，我们将进行幽门螺杆菌 有或无E-cad抑制的MNP-有机物共培养中的感染实验和两个新的 带有MNP特异性E-cad缺失的转基因小鼠模型，我们将绘制E-cad MNPs的分布图谱 在健康和感染幽门螺杆菌的人的胃里。在具体目标2中，我们将利用单细胞RNA 胃上皮细胞和MNP制备中的测序以识别和评估其他受体和 介导胃MNPs和上皮细胞之间细胞间相互作用的配体。确定的候选人 受体-配体对将通过分析胃组织切片和功能实验来验证。我们的 这项研究在概念上是创新的，因为它解决了MNP E-cad在胃中表达的作用 这是因为它将识别胃肠道中的MNPs用来相互作用的受体-配体相互作用 与上皮层。这项拟议的研究具有重要意义，因为了解 MNPs对胃上皮细胞的免疫监视和黏附最终可能为新的 调节胃对幽门螺杆菌的反应和对抗感染的策略。

SUMMARY Stomach infections with H. pylori are a significant cause of morbidity and mortality, leading to chronic gastritis, peptic ulcer disease and gastric cancer. While significant research efforts have been devoted to studying H. pylori-induced gastric pathogenesis and inflammation, the immune mechanisms specific to the gastric mucosa are still not very well understood. Importantly, how mononuclear phagocytes (MNPs) in the stomach access the luminal H. pylori bacteria for stimulation and regulation of T cell responses is unclear. Unlike the intestine, the stomach lacks M cells that are specialized for antigen transport from the lumen to the lamina propria. However, a large proportion of gastric MNPs are positioned in direct contact with the gastric epithelial layer, which likely supports efficient epithelial immunosurveillance including transepithelial dendrite formation by the MNPs. The receptors and ligands that control these functionally important adhesive interactions between the gastric epithelium and the MNPs are unknown. In preliminary studies, we have identified homotypic interactions between E-cadherin (E-cad) expressed on the epithelial cells and E-cad expressed by a subset of gastric MNPs as a potential candidate mechanism for MNP binding to the gastric epithelium. The overarching goal of the current proposal is to identify the receptor-ligand (R-L) interactions that MNPs in the stomach utilize to adhere to the gastric epithelium and to define the functional outcome of these interactions for gastric immunity. In Specific Aim 1, we will determine the role of E-cad-mediated MNP- epithelial cell engagement for MNP function in H. pylori infection. To achieve this aim, we will perform H. pylori infection experiments in MNP-organoid co-cultures with and without E-cad inhibition and in two novel transgenic mouse models with MNP-specific E-cad deletions, and we will map the distribution of E-cad+ MNPs in the stomach of healthy and H. pylori-infected individuals. In Specific Aim 2, we will utilize single cell RNA sequencing in gastric epithelial cell and MNP preparations to identify and evaluate additional receptors and ligands that mediate cell-cell interactions between gastric MNPs and epithelial cells. Identified candidate receptor-ligand pairs will be validated by analyzing gastric tissue sections and in functional experiments. Our research is conceptually innovative, because it addresses the role of MNP E-cad expression in the stomach and because it will identify receptor-ligand interactions that MNPs in the gastrointestinal tract utilize to interact with the epithelial layer. The proposed research is significant, because understanding the mechanisms of gastric epithelial immunosurveillance and adhesion by MNPs may ultimately inform the development of novel strategies to modulate the gastric response to H. pylori and combat infection.