Defining receptor-ligand interactions in gastric epithelial immunosurveillance

总结 胃感染H.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。虽然已经投入了大量的研究努力， 研究H.幽门螺杆菌引起的胃的发病机制和炎症，免疫机制的具体 胃粘膜仍然没有很好的了解。重要的是，如何单核吞噬细胞（MNP）在 胃进入腔H。幽门螺杆菌刺激和调节T细胞反应的机制尚不清楚。 与肠不同，胃缺乏专门用于将抗原从腔运输到胃的M细胞。 固有层然而，大比例的胃MNP定位成与胃粘膜直接接触。 上皮层，可能支持有效的上皮免疫监视，包括跨上皮树突 由MNP组成。控制这些功能重要的粘合剂的受体和配体 胃上皮和MNP之间的相互作用是未知的。在初步研究中， 鉴定了上皮细胞上表达的E-cadherin（E-cad）和E-cad之间的同型相互作用 由胃MNP的子集表达，作为MNP结合胃粘膜的潜在候选机制。 上皮当前提案的首要目标是确定受体-配体（R-L）相互作用， 胃中的MNP用于粘附于胃上皮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的作用。 上皮细胞参与H.幽门感染为了实现这一目标，我们将执行H。幽门 在有和没有E-cad抑制MNP-类器官共培养物中以及在两种新的 MNP特异性E-cad缺失的转基因小鼠模型，我们将绘制E-cad+ MNP的分布图， 在健康和H的胃中。幽门螺杆菌感染者在具体目标2中，我们将利用单细胞RNA 在胃上皮细胞和MNP制备物中进行测序以鉴定和评估另外的受体， 配体介导胃MNP和上皮细胞之间的细胞-细胞相互作用。识别的候选 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 这项研究在概念上是创新的，因为它解决了MNP E-cad表达在胃中的作用。 并且因为它将识别胃肠道中的MNP用于相互作用的受体-配体相互作用， 与上皮细胞层。这项研究是有意义的，因为了解的机制 胃上皮细胞的免疫监视和MNP的粘附可能最终会导致新的胃溃疡的发生。 调节胃对H.幽门螺杆菌和对抗感染。

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.