ROLE OF CYTOKINES IN MEDIATING ORAL TOLERANCE

我们以前研究了口服耐受髓鞘碱性蛋白（MBP）， 刘易斯大鼠EAE模型。 我们已经证明，喂养MBP 产生调节细胞，通过释放TGF-β抑制EAE 在被喂食抗原触发后。 最近，我们发现 口服抗原也能产生T细胞， Th 2型，因为它们在被进食触发后分泌IL-4。 抗原的 我们还发现，根据抗原的剂量， 产生主动抑制或克隆无反应性，并可证明 根据细胞因子模式。 我们现在已经开始研究 EAE小鼠模型中的耐受性，这将允许更好的免疫学 口服耐受机制的表征。 以下 具体目标是：1）在MBP-TcR转基因小鼠中， 主动抑制、克隆缺失和克隆无能发生的程度 在口服抗原后 三种可能的机制 抗原驱动的外周耐受可以在口服后产生， 给予抗原。 使用MBP-TcR转基因动物的研究 将允许描绘这些途径中的哪一个发生以及这些因素 影响一个途径而不是另一个途径。 我们假设低剂量 口腔抗原通过一种独特的粘膜途径被处理， Peyer结中的调节性T细胞，而高剂量口服抗原导致 通过在传代后全身递送抗原， 穿过内脏 MBP-TcR动物也将使我们能够确定 口服抗原后发生何种程度的克隆缺失， 与口服耐受性相关的肠中局部发生无反应性。 （二） TGF-β、IL-10和IL-4在介导口腔黏膜炎症中的相对作用 宽容？ 口服施用的抗原产生调节细胞， 通过在抗原特异性后分泌抑制性细胞因子起作用 触发。 这些细胞因子在口服耐受中的相对作用将 使用体内施用的抗细胞因子抗体进行研究， 细胞因子转基因动物和细胞因子缺陷动物。 3)是什么 共刺激分子在诱导口服耐受中的作用？ 与口服耐受性相关的一个基本问题是， 给予的抗原优先激活产生IL-4、IL-10 和TGF-β。 我们假设产生这些细胞因子的T细胞 需要与所需的那些在性质上不同的共刺激信号 而抗原呈递的粘膜途径 提供激活Th 2和TGF-β T细胞的信号，但抑制Th 1细胞， 细胞 这将使用抗B7的单克隆抗体进行研究， 其他共刺激分子和B7缺陷小鼠。 总之， 概述的研究将有助于提供对机制的基本理解 小鼠实验模型中的口服耐受性。

We have previously studied oral tolerance to myelin basic protein (MBP) in the Lewis rat model of EAE. We have demonstrated that feeding MBP generates regulatory cells that suppress EAE by the release of TGF-beta after being triggered by the fed antigen. More recently, we have found that orally administered antigen also generates T cells that are of the Th2 type in that they secrete IL-4 after being triggered by the fed antigen. We have also found that depending on the dose of antigen fed, active suppression or clonal anergy is generated and can be demonstrated according to cytokine patterns. We have now initiated studies of oral tolerance in murine models of EAE which will allow better immunologic characterization of the mechanisms of oral tolerance. The following specific aim will be addressed: 1) In MBP-TcR transgenic mice, to what degree does active suppression, clonal deletion and clonal anergy occur following orally administered antigen? Three potential mechanisms of antigen driven peripheral tolerance can result following orally administered antigen. Investigations using MBP-TcR transgenic animals will allow a delineation of which of these pathways occur and the factors that influence one pathway over the other. We hypothesize that low dose oral antigen is processed through a unique mucosal pathway to activate regulatory T cells in Peyer's patches whereas high dose oral antigen leads to clonal anergy via systemic delivery of antigen following passage through the gut. The MBP-TcR animals will also allow us to determine to what degree clonal deletion occurs following oral antigen and whether anergy occurs locally in the gut in association with oral tolerance. 2) What are the relative roles of TGF-beta, IL-10 and IL-4 in mediating oral tolerance? Orally administered antigens generate regulatory cells which act by secreting suppressive cytokines following antigen specific triggering. The relative role of these cytokines in oral tolerance will be investigated using anti-cytokine antibodies administered in vivo, cytokine transgenic animals, and cytokine deficient animals. 3) What are the roles of costimulatory molecules in the induction of oral tolerance? A fundamental question related to oral tolerance is why orally administered antigen preferentially activates cells producing IL-4, IL-10 and TGF-beta. We hypothesize that T cells producing these cytokines require costimulatory signals qualitatively different from those required for Th1 cells and that the mucosal pathway of antigen presentation provides signals for activating Th2 and TGF-beta T cells, but anergize Th1 cells. This will be investigated using monoclonal antibodies to B7 and other costimulatory molecules and in B7 deficient mice. In summary, the studies outlined will help provide a basic understanding of the mechanisms of oral tolerance in murine experimental models.