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.

IgG 是大多数哺乳动物中主要的循环 Ig 类别。小鼠和人都有 4 种 IgG 同种型，其诱导效应机制的能力不同。鼠 IgG1 激活补体的能力较差， 最短的 IgG 铰链区（可能会限制免疫复合物 (IC) 的形成）并且仅与 1 个刺激物结合 Fcγ 受体（FcγR）。人 IgG4 与小鼠 IgG1 具有相似的特性，但能力应该​​更差 形成 IC，因为它会自发形成单价、双特异性分子。这些观察结果提出了 为什么小鼠 IgG1 和人类 IgG4 会进化，尽管它们的破坏能力可能会降低 病原体。我们假设这些同种型通过限制宿主损伤来提供选择性优势 反应并通过比较 γ1 充足和 γ1 充足和中抗体 (Ab) 介导的疾病的发展来研究这一点 缺乏的老鼠。我们的结果支持我们的假设：γ1 充足的小鼠不会因免疫接种而受损 有效的抗原，而同样免疫的 γ1 缺陷小鼠死于补体和 FcγR 独立性 大 IC 阻塞肾小球毛细血管。 IgG1 Abs 抑制大 IC 形成，效果更佳 比具有更长铰链区的 IgG2a 或 IgG2b 更有效。 γ1 缺陷小鼠也会产生 2 种补体- 和 FcγR 依赖性疾病、胶原诱导的关节炎和实验性自身免疫性重症肌无力， 在相同遗传背景下，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问题：（1）铰链区存在差异吗？ 长度充分解释了 IgG1 比其他 IgG 同种型破坏大 IC 形成的能力更强； (2) 是 我们对小鼠 IgG 同种型的观察结果与人类相关； (3) 小鼠 IgG1 能否改善已确定的 Ab介导的疾病。这些问题将通过以下具体目标来解决： 1. 确定较短的铰链区长度是否会促进小鼠 IgG 抑制 Ab- 的能力 介导的疾病。我们将交换小鼠 IgG1 和 IgG2b 铰链区，并最小化和最大化 IgG1 铰链 区长度并使用产生的嵌合单克隆抗体来研究短铰链区是否限制 补体非依赖性和补体依赖性疾病模型中的疾病严重程度。 2. 确定我们对小鼠 IgG 同型的观察结果是否与人类相关。嵌合抗TNP 具有人 γ1、γ2、γ3 或 γ4 恒定区的 mAb，以及具有突变的抗 TNP mAb 将产生人类 γ4 恒定区，防止单价、双特异性抗体分子的形成 比较了体外破坏 IC 产生和体内预防 IC 肾病的能力。 3. 确定诱导效应功能相对较差的 Ab 同种型是否可以抑制 确定了抗体介导的疾病。将使用主动和被动小鼠模型进行研究 大疱性表皮松解症，一种由 Abs 引起的补体和 FcγR 依赖性水疱性皮肤病 VII 型胶原蛋白 (Col7)，以确定 IgG1 抗 Col7 抗体是否可以导致既定疾病消退。