CD180(RP105) Regulation of TLR and BCR Responses in B Cells

描述（由申请人提供）：本提案将研究 CD180 刺激对 B 细胞免疫调节的潜力，并研究 CD180 与 BCR 和 TLR 信号相互作用的机制。 TLR4 和 TLR2 介导的 B 细胞增殖和 T 细胞非依赖性抗体反应（TI-1 反应）需要 CD180 (RP105) 表达。我们建议对 CD180 受体进行全面研究，包括研究 CD180 与 BCR 和 TLR 信号相互作用的机制，结合小鼠中 CD180 激活的分析，以确定对表达 NP 特异性转基因高亲和力 BCR (B1-8hi) 的抗原特异性 B 细胞的影响，以及对 NP-CGG 抗体反应的影响。这些实验将确定 CD180 激活是否可以作为致敏信号，导致抗原结合后选择性 B 细胞缺失。 CD180被认为在B细胞中协调或整合TLR4和TLR2信号与BCR信号，以驱动所有同种型的抗原特异性抗体反应。我们发现 CD180 刺激与 TLR 激动剂一起导致 B 细胞协同增殖，并增强 B 细胞炎症细胞因子 IL-6、IL-10 和 TNF1 的产生。相反，CD180 刺激的 B 细胞的增殖受到同时 BCR 刺激的抑制，并且 CD180 激活的 B 细胞对抗 BCR 凋亡敏感。该资助的第二个主要部分将利用在哺乳动物细胞中表达的可溶性 CD180/MD-1 的分子工程来帮助识别和潜在地阻断天然 CD180 配体。我们还将表达抗人和抗小鼠 CD180 scFv-Ig 融合蛋白。 scFv 将用野生型或突变的人和小鼠 Ig 尾构建，以研究 FcR 结合对 CD180 信号的调节。这些结果将有助于阐明 CD180 作为 TLR2 和 TLR4 主调节因子的作用，并将有助于确定 CD180 作为抗体治疗靶点的潜力。这项工作还将导致重组分子的构建和表达，这些重组分子将有助于未来传染病和癌症模型中 CD180 疗法的研究。 公共健康相关性：CD180 是调节 B 细胞中 TLR4 和 TLR2 功能的关键受体，并且可能是免疫调节的重要靶点。这笔资助将表达用于 CD180 刺激的重组分子，并将测试 CD180 作为删除自身反应性 B 细胞的治疗靶点的潜力。

DESCRIPTION (provided by applicant): This proposal will investigate the potential for B cell immunoregulation by CD180 stimulation and study the mechanisms of CD180 interactions with BCR and TLR signals. CD180 (RP105) expression is required for TLR4 and TLR2-mediated B cell proliferation and T cell- independent antibody responses (TI-1 response). We propose a comprehensive study of the CD180 receptor, including studies of the mechanisms of CD180 interaction with BCR and TLR signals, combined with analysis of CD180 activation in mice to determine the effect on antigen-specific B cells expressing transgenic high affinity BCR (B1-8hi) specific for NP, and on the antibody response to NP-CGG. These experiments will determine whether CD180 activation may serve as a sensitization signal that could result in selective B cell deletion upon antigen binding. CD180 is thought to coordinate or integrate the TLR4 and TLR2 signals with BCR signals in B cells to drive an antigen specific antibody response of all isotypes. We have found that CD180 stimulation together with TLR agonists results in synergistic B cell proliferation, and augments B cell production of inflammatory cytokines IL-6, IL-10, and TNF1. In contrast, proliferation of CD180-stimulated B cells is inhibited by simultaneous BCR stimulation, and CD180-activated B cells are sensitized to anti-BCR apoptosis. The second major component of this grant will use molecular engineering of soluble forms of CD180/MD-1 that are expressed in mammalian cells to help identify and potentially block natural CD180 ligands. We will also express anti-human and anti-mouse CD180 scFv-Ig fusion proteins. The scFvs will be constructed with wt or mutated human and mouse Ig tails in order to study the regulation of CD180 signals by FcR binding. The results will help clarify the role of CD180 as a master regulator of TLR2 and TLR4 and will help determine the potential for CD180 as a target for antibody-based therapy. The work will also result in construction and expression of recombinant molecules that will be useful in future studies of CD180 therapy in infectious disease and cancer models. PUBLIC HEALTH RELEVANCE: CD180 is a critical receptor for regulation of TLR4 and TLR2 function in B cells and could be an important target for immunoregulation. This grant will express recombinant molecules for CD180 stimulation and will test the potential for CD180 as a therapeutic target for deletion of autoreactive B cells.