Examining IgG4 sialylation as a gain of function post-translation modification in IgG4-related diseases

项目摘要/摘要。 IgG4相关疾病(IgG4-RDS)是一组以纤维化为特征的相关自身炎症性疾病家族 病变由CD4T细胞和IgG4浆细胞组成，并显著升高的寡克隆IgG4。然而， 目前尚不清楚IgG4抗体是否与IgG4-RD病理有关。尽管存在巨大的临床问题 免疫治疗的成功，关于免疫球蛋白G4的生物学与免疫球蛋白1的关系知之甚少。我们的长期目标是 了解糖基化对抗体生物学的作用和调节，最终调控抗体效应物 在体外和体内发挥作用。这项应用的总体目标是全面剖析细胞毒性 唾液酸化的IgG4的活性。我们的中心假设是IgG4中的自身抗原特异性的IgG4-RD是唾液酸化的，并且 参与了IgG4-RD的病理过程。我们的方法结合了从IgG4-RD血清中鉴定免疫球蛋白 和健康患者，同时精确检测糖工程IgG4的受体结合和效应功能 化验。 我们的假设是由研究策略的方法小节中的初步数据提供的 一节。这项拟议的研究的基本原理是了解IgG4如何介导细胞毒效应 功能将使人们能够对免疫球蛋白生物学有新的见解，并可能导致创新的基于抗体的开发 治疗。我们将测试我们的中心假设，从而通过追求 以下三个具体目标使用生物物理实验相结合，并在体外和体内功能 化验。 1)确定γ-RD中总和自身抗原特异性免疫球蛋白的糖基化和Fc-IgGRs结合谱。 假设：唾液酸化使FcγR与Ig G4结合。 2)体外检测唾液酸化的IgG4的效应功能。假说：唾液酸化的IgG4介导效应器 细胞特异性促炎效应器功能。 3)唾液酸化IgG4体内效应功能的测定。假说：唾液酸化的IgG4能促进 炎症效应分子在体内发挥作用。 这项建议预计将具有广泛的临床意义，范围从IgG4滴度升高的疾病 与病理或解决方案以及免疫疗法的设计有关，并代表着一种 通过强调IgG4的细胞毒能力，从根本上改变现状。

Project Summary/Abstract. IgG4-related diseases (IgG4-RDs) are a family of related autoinflammatory diseases characterized by fibrotic lesions comprised of CD4+ T cells and IgG4+ plasma cells, and markedly elevated oligoclonal IgG4. However, whether IgG4 antibodies contribute to IgG4-RD pathology remains unclear. Despite the tremendous clinical success of immunotheraputics, little is known regarding IgG4 biology relative to IgG1. Our long-term goals are to understand the role and regulation of glycosylation to antibody biology, to ultimately modulate antibody effector functions in vitro and in vivo. The overall objective of this application is to comprehensively dissect cytotoxic activity of sialylated IgG4. Our central hypothesis is autoantigen-specific IgG4 in IgG4-RD is sialylated, and contributes to the pathology Of IgG4-RD. Our approach combines characterizing IgG from the sera of IgG4-RD and healthy patients, while examining precisely glycoengineered IgG4 in receptor binding and effector function assays. Our hypothesis is informed by preliminary data shown here in the Approach subsection of the Research Strategy section. The rationale that underlies the proposed research is understanding how IgG4 mediate cytotoxic effector function will enable new insights into IgG biology, and may lead to development of innovative antibody-based therapies. We will test our central hypothesis and, thereby, attain the objective of this application by pursuing the following three specific aims using a combination of biophysical experiments, and in vitro and in vivo functional assays. 1) Define the glycosylation and FcγRs-binding profiles of total and autoantigen-specific IgG in IgG4-RD. Hypothesis: Sialylation enables FcγR binding by IgG4. 2) Examine the effector functions of sialylated IgG4 in vitro. Hypothesis: Sialylated IgG4 mediates effector cell-specific pro-inflammatory effector functions. 3) Determine the in vivo effector functions of sialylated IgG4. Hypothesis: Sialylated IgG4 exerts pro- inflammatory effector functions in vivo. This proposal is expected to have broad clinical implications, ranging from diseases where elevated IgG4 titers are associated in the pathology or resolution, as well as to design of immunotherapeutics, and represents a substantive departure from the status quo by underscoring the cytotoxic capacity of IgG4.