Hormonal control of IgG galactosylation in murine arthritis

描述（由申请人提供）：人免疫球蛋白G （IgG）的效应功能依赖于抗体Fc部分内部的两个聚糖。成人类风湿关节炎（RA）表现出这些聚糖的特征性异常：较高比例的抗体使用缺乏末端半乳糖的糖型。这种抗体更有效地固定补体，因此可能更容易引发组织炎症。然而，控制抗体糖基化的因素尚不清楚。在对RA患者IgG聚糖的研究过程中，我们发现了令人信服的证据，表明激素环境是体内IgG聚糖结构的关键决定因素。在这里，我们表明我们可以在小鼠炎症性关节炎的K/BxN模型中模拟这种人类生理学的关键方面，从而实现详细的机制探索。因此，我们提出两个目标。首先，我们将通过对培养的B细胞和关节炎前K/BxN小鼠进行激素调控，研究诱导IgG糖基化变化的内分泌因素，并研究由此产生的IgG糖型。其次，我们将通过一系列实验来研究激素驱动的IgG糖基化变化对关节炎的体内重要性，这些实验将激素操纵的K/BxN小鼠的IgG转移到正常受体动物。聚糖在我们期望观察到的差异中的作用将通过体外酶处理IgG来评估，我们进一步期望通过实验来明确回答特定聚糖变化在致病性抗体致关节炎性中的重要性。因此，这些研究将有助于了解抗体糖基化的基本生物学，揭示炎症性关节炎中的性别差异，并确定是否以及如何操纵IgG聚糖来治疗RA和相关疾病。

DESCRIPTION (provided by applicant): The effector functions of human immunoglobulin G (IgG) depend on two glycans internal to the Fc portion of the antibody. Adults with rheumatoid arthritis (RA) exhibit a characteristic abnormality in these glycans: a higher proportion of antibodies employ glycoforms lacking terminal galactose. Such antibodies fix complement more efficiently and may therefore be more likely to incite tissue inflammation. However, the factors governing antibody glycosylation are not understood. In the course of studies into IgG glycans in RA patients, we have uncovered compelling evidence that hormonal milieu is a key in vivo determinant of IgG glycan structure. Here, we show that we can model key aspects of this human physiology in the murine K/BxN model of inflammatory arthritis, enabling detailed mechanistic exploration. We therefore propose two Aims. First, we will investigate the endocrine factors that induce changes in IgG glycosylation by subjecting cultured B cells and pre-arthritic K/BxN mice to hormonal manipulation and studying the resulting IgG glycoforms. Second, we will investigate the in vivo importance of hormone-driven IgG glycosylation changes to arthritis through a series of experiments in which IgG from hormonally-manipulated K/BxN mice is transferred to normal recipient animals. The role of glycans in the differences we expect to observe will be evaluated by ex vivo enzymatic manipulation of the IgG, experiments which we further anticipate to answer definitively the importance of specific glycan changes in the arthritogenicity of pathogenic antibodies. These studies will therefore contribute to the understanding of the basic biology of antibody glycosylation, shed fresh light on gender discrepancies in inflammatory arthritis, and determine whether and how IgG glycans might be manipulated for the treatment of RA and related diseases.