Intestinal M Cells: Uptake and Fate of Enteric Pathogens

描述(申请人提供)：肠道病原体可利用 M细胞侵袭肠粘膜的转运活性。鼠标 病原体呼肠孤病毒(1型Lang)选择性黏附于成年小鼠的M细胞 在系统传播之前，在Peyer的斑块中建立感染。 呼肠孤病毒为了解病原体-M细胞提供了一个很好的模型 坚持并跟踪病毒致病的最早阶段 佩尔的斑块。我的目的是阐明分子间的相互作用 呼肠孤病毒选择性地附着在M细胞上。假设呼肠孤病毒 外衣壳蛋白Sigma 1是M细胞的病毒粘附素 结合试验将使用重组衣壳蛋白和 重组的病毒核心。我们将使用亲和的方法来分离根尖 上皮细胞的膜糖偶联物，以及覆盖方法 识别上皮膜糖蛋白和/或糖脂 充当呼肠孤病毒受体。此外，还有一种假设，即完整的细胞膜粘蛋白 可以对呼肠孤病毒结合部位进行掩膜检测。目标二是使用呼肠孤病毒 阐明分泌型IgA可能具有的多重矛盾效应的模型 当病原体通过M细胞进入时，以及随后的粘膜免疫反应。 免疫球蛋白可以预防粘膜感染，但免疫球蛋白A抗原复合体可以黏附M 细胞顶面。需要检验的统一假设是1) 天然分泌的抗衣壳蛋白免疫球蛋白可通过包裹保护 粘液中的病毒和防止粘膜接触，但2)如果病毒包被IgA 成功与FAE接触，可通过IgA黏附于M细胞，进入 粘膜。此外，内源性IgA涂层可能的保护作用 将使用IgA基因敲除小鼠和正常小鼠检测M细胞上的。AIM III将 检测呼肠孤病毒和呼肠孤病毒感染细胞在M细胞后的命运 运输。我们将检验两个假设：1)M细胞传播的呼肠孤病毒是 被树突状细胞(DC)中的特定亚群摄取并感染 上皮下穹隆区域，以及2)粘膜佐剂霍乱毒素可以 推动携带病毒或病毒大小的颗粒的分布式控制系统移动到其他 在Peyer‘s Patch和其他地方的站点，促进病毒传播。这个 拟议的研究将阐明M细胞是如何为粘膜“选择”病原体的 免疫监测，病原体如何利用M细胞运输途径 导致疾病，以及疫苗和疫苗载体如何有效地靶向 对粘膜免疫系统的影响。

DESCRIPTION (provided by applicant): Enteric pathogens can exploit the transport activity of M cells to invade the intestinal mucosa. The mouse pathogen reovirus (Type 1 Lang) adheres selectively to M cells in adult mice and establishes infection in Peyer's patches before spreading systemically. Reovirus provides an excellent model for understanding pathogen-M cell adherence and for following the earliest stages of viral pathogenesis in Peyer's patches. Aim I is to elucidate the molecular interactions that allow reovirus to selectively adhere to M cells. The hypothesis that the reovirus outer capsid protein sigma 1 is the viral adhesin responsible for M cell binding will be tested using recombinant outer capsid proteins and reconstituted viral cores. We will use affinity methods to separate apical membrane glycoconjugates of epithelial cells, and overlay approaches to identify the epithelial membrane glycoproteins and/or glycolipids that can serve as reovirus receptors. Also, the hypothesis that integral membrane mucins can mask reovirus binding sites will be tested. Aim II is to use the reovirus model to clarify the multiple, paradoxical effects that secreted IgA may have on entry of pathogens via M cells, and on subsequent mucosal immune responses. IgA can prevent mucosal infection, yet IgA-antigen complexes can adhere to M cell apical surfaces. A unifying hypotheses to be tested is that 1) naturally-secreted IgAs against outer capsid proteins can protect by entrapping virus in mucus and preventing mucosal contact, but 2) if virus coated with IgA succeeds in contacting the FAE, it can adhere to M cells via IgA and enter the mucosa. In addition, the possible protective effect of the endogenous IgA coat on M cells will be examined using IgA knockout and normal mice. Aim III will examine the fate of reovirus and reovirus-infected cells after M cell transport. We will test two hypotheses: 1) that M cell-transported reovirus is taken up by and infects a specific subset of dendritic cells (DCs) in the subepithelial dome region, and 2) that the mucosal adjuvant cholera toxin can drive the movement of the DCS carrying virus or virus-sized particles to other sites in Peyer's patches and beyond, facilitating viral dissemination. The proposed studies will elucidate how M cells "select" pathogens for mucosal immune surveillance, how pathogens exploit the M cell transport pathway to cause disease, and how vaccines and vaccine vectors may be efficiently targeted to the mucosal immune system.