Wimpy antibody isotypes protect against antibody-mediated disease

Wimpy 抗体同种型可预防抗体介导的疾病

• 批准号: 9287287
• 负责人: FRED Douglass FINKELMAN
• 金额: $ 37.18万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-01-25 至 2021-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9287287
• 关键词: Acute Lung Injury; Address; Affect; Affinity; Antibodies; Antigen-Antibody Complex; Antigens; Binding; Bispecific Antibodies; Bulla; Characteristics; Collagen Type VII; Collagen-Induced Arthritis; Complement; Complement 2; Complement Activation; Development; Disease; Disease model; Dissociation; Epidermolysis Bullosa Acquisita; Experimental Autoimmune Myasthenia Gravis; Genetic; Glomerular Capillary; Human; IgG1; IgG2; IgG3; IgG4; Immune system; Immunization; Immunize; Immunoglobulin Constant Region; Immunoglobulin G; Immunoglobulins; In Vitro; Inflammation; Inflammatory; Inflammatory Response; Kidney; Kidney Diseases; Laboratories; Length; Mammals; Mediating; Monoclonal Antibodies; Mus; Mutate; Obstruction; Oryctolagus cuniculus; Pathogenicity; Pathway interactions; Production; Reagent; Severities; Severity of illness; Testing; Transfusion; crosslink; design; in vivo; man; mouse model; mutant; pathogen; prevent; receptor; response; skin disorder

IgG is the predominant circulating Ig class in most mammals. Both mouse and man have 4 IgG isotypes, which differ in ability to induce effector mechanisms. Murine IgG1 activates complement poorly, has the shortest IgG hinge region (which may limit immune complex (IC) formation) and binds to only 1 stimulatory Fcγ receptor (FcγR). Human IgG4 has similar characteristics to mouse IgG1 and should have even less ability to form ICs because it spontaneously forms univalent, bispecific molecules. These observations raise the question of why mouse IgG1 and human IgG4 evolved, despite their likely reduced ability to damage pathogens. We hypothesized that these isotypes provide a selective advantage by limiting host-damaging responses and studied this by comparing development of antibody (Ab)-mediated disorders in γ1-sufficient and deficient mice. Our results support our hypothesis: γ1-sufficient mice are not damaged by immunization with a potent antigen, while identically immunized γ1-deficient mice die from complement- and FcγR-independent obstruction of glomerular capillaries by large ICs. IgG1 Abs suppress large IC formation and do so more potently than IgG2a or IgG2b, which have longer hinge regions. γ1-deficient mice also develop 2 complement- and FcγR-dependent disorders, collagen induced arthritis and experimental autoimmune myasthenia gravis, more frequently and more severely than γ1-sufficient mice on the same genetic background. Three important questions are suggested by these observations: (1) do differences in hinge region length fully explain the greater ability of IgG1 than other IgG isotypes to disrupt formation of large ICs; (2) are our observations with mouse IgG isotypes human-relevant; and (3) can mouse IgG1 ameliorate an established Ab-mediated disease. These questions will be addressed by the following specific aims: 1. Determine whether short hinge region length promotes the ability of mouse IgG to suppress Ab- mediated disease. We will swap mouse IgG1 and IgG2b hinge regions and minimize and maximize IgG1 hinge region length and use the chimeric monoclonal Abs produced to study whether a short hinge region limits disease severity in complement-independent and complement-dependent disease models. 2. Determine whether our observations with mouse IgG isotypes are human-relevant. Chimeric anti-TNP mAbs that have human γ1, γ2, γ3 or γ4 constant regions, as well as an anti-TNP mAb that has a mutated human γ4 constant region that prevents formation of univalent, bispecific Ab molecules, will be produced and compared for ability to disrupt IC production in vitro and prevent IC kidney disease in vivo. 3. Determine whether an Ab isotype that is relatively poor at inducing effector functions can suppress an established Ab-mediated disorder. Studies will be performed with active and passive mouse models of epidermolysis bullosa acquisita, a complement- and FcγR-dependent blistering skin disease caused by Abs to collagen type VII (Col7), to determine whether IgG1 anti-Col7 Abs can cause established disease to regress.

在大多数哺乳动物中，IgG是主要循环Ig类。鼠标和人都有4个IgG 同种型在影响效应机制的能力上有所不同。鼠IgG1激活完全差，具有 最短的IgG铰链区域（可能限制免疫复合物（IC）形成），仅结合1个刺激性 Fcγ受体（FcγR）。人IgG4具有与鼠标IgG1相似的特征，并且能力甚至应更低 形成IC，是因为它赞助形成通用的双特异性分子。这些观察提出了 小鼠IgG1和人IgG4为什么进化的问题，可能会降低损害能力 病原体。我们假设这些同种型通过限制宿主损害来提供选择性优势 通过比较γ1充足和 不足的小鼠。我们的结果支持我们的假设：γ1充足的小鼠没有通过A的免疫受损 有效的抗原，虽然免疫抑制的γ1缺陷小鼠死于完工和FcγR 大型IC的肾小球毛细血管阻塞。 IgG1 ABS抑制大型IC形成并这样做更多 可能比具有更长的铰链区域的IgG2A或IgG2b。 γ1缺陷小鼠还会发展2个完成 - 和FcγR依赖性疾病，胶原蛋白引起的关节炎和实验性自身免疫性肌无力重症 在相同的遗传背景上，比γ1充足的小鼠更频繁，更严重。 这些观察结果提出了三个重要的问题：（1）铰链区域的差异 长度完全解释了IgG1的能力，而不是其他IgG同种型破坏大型IC的形成的能力。 （2）是 我们对小鼠IgG同种型人类与人相关的观察； （3）鼠标igG1可以改善已建立的 AB介导的疾病。这些问题将由以下具体目的解决： 1。确定短铰链区域长度是否促进了小鼠IgG抑制AB-的能力 介导的疾病。我们将交换鼠标IgG1和IgG2B铰链区域，并最小化并最大化IgG1铰链 区域长度并使用产生的嵌合单克隆ABS来研究短铰链区域是否限制 疾病的严重程度与补体无关和补体依赖性疾病模型。 2。确定我们对小鼠IgG同种型的观察是否与人相关。嵌合抗TNP 具有人γ1，γ2，γ3或γ4常数区域的mAb，以及具有突变的抗TNP mAb 将产生阻止普遍双特异性AB分子形成的人γ4常数区域 比较在体外破坏IC产生并预防体内IC肾脏疾病的能力。 3。确定在诱导效应子功能下相对较差的AB同种型是否可以抑制 建立的AB介导的疾病。研究将使用主动和被动的小鼠模型进行 表皮溶液囊泡囊肿，ABS引起的一种补体和FcγR依赖性皮肤疾病 VII型胶原蛋白（COL7），确定IgG1抗Col7 ABS是否会导致既定疾病退缩。