Structure and Function of the Lymphocyte Fce Receptor

描述(申请人提供)：目前的研究表明，针对CD23茎区域的抗体在人体体外和小鼠体内系统中都能促进IgE的合成。CD23转基因小鼠在所有淋巴细胞和FDCs上过度表达CD23，在蠕虫和明胶/银模型中均表现出显著的IgE生成减少。这些数据提出了一种模型，在该模型中，CD23的作用最初是作为先天免疫的一个组成部分，通过变得不稳定和被切割来传递产生IgE的信号，然后通过在细胞表面过度表达并调节IgE产生。这一延续申请建议研究这些影响的机制。目的#1研究小鼠系统，其中不稳定的单抗19G5在体内提供增强的IgE合成。在目前的资助中，金属蛋白酶ADAM10已经被确定为小鼠和人类中主要的CD23脱落酶。ADAM10在过敏性疾病中的作用将通过制造过表达ADAM10或显性阴性ADAM10的转基因小鼠来模拟。此外，我们还将通过研究CD23与另一种负性信号分子LAX的关系来研究19G5诱导IgE产生的机制。LAX最近被证明既调节CD23的表达，又调节IgE水平。目的#2研究CD23过度表达和CD23失稳对小鼠哮喘模型的调节和疾病加重的影响。我们将利用IgE和新的ADAM10转基因药物来评估抑制嗜酸性粒细胞增多的机制以及CD23调节哮喘表型的能力。目的#3研究人类体外免疫球蛋白E合成模型，包括抗柄抗体促进免疫球蛋白E合成和某些抗凝集素单抗抑制免疫球蛋白E合成的机制。还将探讨ADAM10在人类CD23切割和IgE产生中的重要性，以及LAX的参与。最后，我们将确定从正常和过敏受试者获得的B细胞产生的IgE是否受到CD23失稳或稳定的不同影响。综上所述，这些研究考察了一种天然的免疫球蛋白生成调节剂CD23的作用机制，目的是开发方案来增强CD23的表达，从而调节免疫球蛋白E，以此类推，免疫球蛋白E在其中起主导作用的过敏性疾病。项目说明：这个项目研究了一种自然调节因子控制免疫球蛋白E合成的机制。后者是CD23，是一种低亲和力的IgE受体。积累的证据表明，金属蛋白酶ADAM10对CD23的切割增加了小鼠和人类的IgE产量。这项申请建议研究这一调节机制，以开发控制过敏性疾病的新方案。

DESCRIPTION (provided by applicant): Current studies have indicated that antibodies directed against the stalk region of CD23 cause enhancement of IgE synthesis in both the human in vitro and mouse in vivo systems. CD23 transgenic mice, which overexpress CD23 on all lymphocytes and FDCs, exhibit drastically reduced IgE production in both helminth and alum/ag models. The data suggest a model where the role of CD23 is initially to serve as a component of innate immunity to signal for IgE production by becoming destabilized and cleaved and later by overexpressing at the cell surface and modulating IgE production. This continuation application proposes to investigate the mechanism of these effects. Aim#1 examines the mouse system where the destabilizing mab 19G5 gives enhanced IgE synthesis in vivo. In the current funding, the metalloprotease, ADAM10 has been identified as the primary CD23 sheddase in mouse and humans. The role of ADAM10 in allergic disease will be modeled by making transgenic mouse that overexpress ADAM10 or dominant negative ADAM10. In addition, we will examine the mechanism for the 19G5-induced IgE production by investigating the association of CD23 with another negative signaling molecule, LAX, which has recently been shown to both modulate CD23 expression and regulate IgE levels. Aim#2 will investigate the affect of CD23 overexpression and CD23 destabilization on the mouse asthma model with respect to both modulation and exacerbation of disease. We will utilize both IgE and the new ADAM10 transgenics in order to evaluate the mechanism of the suppression of eosinophilia as well as the capacity of CD23 to modulate the asthma phenotype. Aim#3 will investigate the human in vitro IgE synthesis models with respect to the mechanisms involved in IgE synthesis enhancement, seen with anti-stalk antibodies and synthesis suppression, seen with certain anti-lectin mabs. The importance of ADAM10 in human CD23 cleavage and IgE production will also be explored as will the involvement of LAX. Finally, we will determine if IgE production by B cells obtained from normal and allergic subjects is affected differently by destabilization or stabilization of CD23. In summary, these studies examine the mechanism of action of a natural regulator of IgE production, CD23, with the objective of developing protocols to enhance CD23 expression and thereby regulate IgE, and by analogy, allergic disease in which IgE plays a dominant role.Project Narrative: This project examines mechanisms involved in control of IgE synthesis by a natural regulator. The latter is CD23, a low affinity receptor for IgE. Accumulated evidence indicates that cleavage of CD23 by the metalloprotease ADAM10 increases IgE production in both mouse and humans. This application proposes to study mechanisms involved in this regulation in order to develop new protocols to control allergic disease.