CELLULAR AND MOLECULAR MECHANISMS FOR MUCOSAL IMMUNITY

描述(由申请者提供)：这项资助工作最近发现 佩尔氏斑，这是主要的粘膜诱导部位在 胃肠道(GI)免疫系统，对粘膜IgA不是严格要求 口服免疫后的抗体反应。宫内给药的小鼠 淋巴毒素-β受体(LTbR)-Ig不形成Peyer‘s斑块；然而， 这些小鼠表现为肠系膜淋巴结，排出了小肠。在……里面 在这方面，LTbR-Ig经口免疫处理的小鼠的蛋白质和霍乱 毒素(CT)作为粘膜佐剂可诱导小鼠产生明显的IgA抗体应答 胃肠道。初步研究表明，肠系膜淋巴结 作为这些IgA抗体反应的代偿部位。另外，我们发现， 佩耶贴片是口服蛋白质耐受性的严格要求 如卵清蛋白(OVA)，而不是半抗原，如三硝基苯磺酸 酸(TNBS)。明确证明口腔耐受需要佩耶贴片 TnBS与OVA结合的实验提供给蛋白质 (TNP-OVA)在LTbR-Ig中未能诱导对TNBS或OVA的口服耐受 治疗过的小鼠。这些实验揭示了需求的根本差异 在粘膜免疫和口服耐受性方面的Peyer‘s补片，并为我们提供 有一个平台可以同时研究胃肠道的这些反应。在……里面 这次续签申请，第一个具体目标将是 LTbR-Ig处理的肠系膜淋巴结，以Peyer‘s Patch缺失小鼠为替代 免疫球蛋白诱导位点。我们将用B细胞和浆细胞来表征 重点是u&gt；a开关，以及对于转化生长因子-β1的表达。第二个具体目标 将重点放在CD4+T辅助(Th)细胞，特别是Th1型细胞上 胃肠道粘膜免疫球蛋白A抗体反应。主要重点将放在 表达OVA的重组沙门氏菌对小鼠粘膜免疫的诱导作用 Peyer‘s补丁缺失小鼠。第三个具体目标将评估 Peyer‘s斑块中抗原提呈细胞(APC)对IgA免疫和口服免疫的比较 耐受性诱导。重点将放在树突状细胞(DC)上，在 自然环境或用Flt3配体激活后。第四个具体问题 AIM将使用OVA多肽特异性四聚体来跟踪来自 黏膜免疫球蛋白A或口腔条件下的Peyer‘s补片 耐受性反应。最后一个特定的目标将桥接粘膜的IgA抗体反应 用口服耐受诱导。在这方面，我们将研究 从口服耐受到IgA免疫的转换，当CT用作 一种口服佐剂。从这笔赠款中产生的开创性发现 自1982年以来的努力将再次集中在细胞和分子上 诱导胃肠道粘膜免疫或口服耐受所需的事件 一条小路。

DESCRIPTION (provided by applicant): This grant effort has recently discovered that the Peyer's patches, which are the major mucosal inductive sites in the gastrointestinal (GI) immune system, are not strictly required for mucosal IgA antibody (Ab) responses after oral immunization. Mice treated in utero with lymphotoxin-beta receptor (LTbR)-Ig do not develop Peyer's patches ; however, these mice exhibit mesenteric lymph nodes which drain the small intestine. In this regard, oral immunization of LTbR-Ig treated mice with protein and cholera toxin (CT) as mucosal adjuvant resulted in significant IgA Ab responses in the GI tract. Preliminary studies suggested that the mesenteric lymph nodes served as a compensatory site for these IgA Ab responses. In addition, we discovered that Peyer's patches are a strict requirement for oral tolerance to proteins such as ovalbumin (OVA), but not to haptens such as trinitrophenyl sulfonic acid (TNBS). Clear proof that Peyer's patches are required for oral tolerance to proteins was provided by an experiment where TNBS conjugated to OVA (TNP-OVA) failed to induce oral tolerance to either TNBS or to OVA in LTbR-Ig treated mice. These experiments reveal fundamental differences in a requirement for Peyer's patches in mucosal immunity versus oral tolerance and provide us with a platform to simultaneously study these responses in the GI tract. In this renewal application, the first specific aim will characterize the mesenteric lymph nodes of LTbR-Ig treated, Peyer's patch null mice as alternate IgA inductive sites. We will characterize B cells and plasma cells with emphasis on u > a switches, and for TGF-b 1 expression. The second specific aim will focus on CD4+ T helper (Th) cells and especially Th1-type cells for mucosal IgA Ab responses in the GI tract. Major emphasis will be placed on recombinant Salmonella expressing OVA for initiation of mucosal immunity in Peyer's patch-null mice. The third specific aim will assess the role of antigen-presenting cells (APCs) in Peyer's patches for IgA immunity versus oral tolerance induction. Emphasis will be placed on dendritic cells (DCs), in a natural environment or after activation with Flt3 ligand. The fourth specific aim will employ OVA peptide-specific tetramers to track CD4+ T cells from Peyer's patches to the periphery under conditions for mucosal IgA or oral tolerance responses. The last specific aim will bridge mucosal IgA Ab responses with oral tolerance induction. In this regard, we will study the mechanism of the switch from oral tolerance to IgA immunity which occurs when CT is used as an oral adjuvant. The seminal findings which have emanated from this grant effort since 1982 will again remain focused on the cellular and molecular events required for induction of mucosal immunity or oral tolerance in the GI tract.