Intestinal M Cells: Uptake and Fate of Enteric Pathogens

描述（由申请人提供）：肠道病原体可以利用 运输活动的M细胞侵入肠粘膜。鼠标 病原体呼肠孤病毒（1型Lang）在成年小鼠中选择性粘附于M细胞 并在系统性传播之前在派尔集合淋巴结中建立感染。 呼肠孤病毒为了解病原体-M细胞提供了一个很好的模型 粘附性和以下病毒发病机制的最早阶段， 派伊尔淋巴结。目的一是阐明分子间的相互作用， 呼肠孤病毒选择性粘附于M细胞。呼肠孤病毒 外衣壳蛋白sigma 1是负责M细胞的病毒粘附素， 将使用重组外衣壳蛋白测试结合， 重组病毒核心我们将使用亲和方法分离顶端 上皮细胞的膜糖缀合物，以及 鉴定上皮膜糖蛋白和/或糖脂， 作为呼肠孤病毒受体。此外，假设膜粘蛋白 可以掩蔽呼肠孤病毒结合位点进行检测。目的二是利用呼肠孤病毒 一个模型，以澄清多种，矛盾的影响，分泌型伊加可能有 病原体通过M细胞进入，以及随后的粘膜免疫应答。 伊加可以预防粘膜感染，但IgA-抗原复合物可以粘附在M 细胞顶面。一个有待检验的统一假设是：1） 天然分泌的抗外衣壳蛋白的IgA可以通过包埋 病毒在粘液和防止粘膜接触，但2）如果病毒与伊加包被 成功地接触FAE，它可以通过伊加粘附到M细胞并进入 粘膜此外，内源性伊加涂层可能的保护作用， 将使用伊加敲除小鼠和正常小鼠检查对M细胞的影响。Aim III将 检查M细胞后呼肠孤病毒和呼肠孤病毒感染细胞的命运 运输我们将测试两个假设：1）M细胞运输的呼肠孤病毒是 被树突状细胞（DC）的特定亚群摄取并感染， 上皮下圆顶区，和2）粘膜佐剂霍乱毒素可以 驱动携带病毒或病毒大小的颗粒的DCS移动到其他 派尔集合淋巴结及其他部位，促进病毒传播。的 拟议的研究将阐明M细胞如何“选择”粘膜病原体， 免疫监视，病原体如何利用M细胞转运途径， 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.