Unlocking Envelope: A New Strategy for a Functional Cure Through Antibody-Dependent Cell-Mediated Cytotoxicity

解锁包膜：通过抗体依赖性细胞介导的细胞毒性实现功能性治愈的新策略

• 批准号: 9925499
• 负责人: Marzena Elzbieta Pazgier
• 金额: $ 45.66万
• 依托单位: HENRY M. JACKSON FDN FOR THE ADV MIL/MED
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-03 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9925499
• 关键词: Acquired Immunodeficiency Syndrome; Anti-Retroviral Agents; Antibodies; Antibody Therapy; Binding; Binding Sites; Bone Diseases; CD4 Antigens; CD4 Positive T Lymphocytes; Cardiovascular Diseases; Cell surface; Cells; Comorbidity; Data; Development; Down-Regulation; Epitopes; Exposure to; Fc Receptor; Glycoproteins; Goals; HIV; HIV Envelope Protein gp120; HIV Infections; Health; Human; Immune Targeting; Impaired cognition; In Vitro; Individual; Interruption; Laboratories; Lead; Length; Malignant Neoplasms; Maps; Mediating; Methods; Molecular Conformation; Monoclonal Antibodies; Research; Shock; Site; Specificity; Structure; Surface; System; Testing; Therapeutic antibodies; Transfer RNA; Viral; Viral reservoir; Virus; Virus Replication; antibody-dependent cell cytotoxicity; antiretroviral therapy; arm; base; cell envelope; design; experience; experimental study; immune checkpoint; immunological status; innovation; mimetics; neutralizing antibody; novel; novel strategies; novel therapeutics; prevent; public health relevance; response; success; unnatural amino acids; virus envelope; weapons

Project Summary/Abstract Strategies for a functional cure with use of non-neutralizing antibodies (nnAbs) that eliminate HIV-infected cells through Fc receptor (FcR) effector function including antibody dependent cellular cytoxicity (ADCC) remain a significant yet largely unexploited avenue of research.This project is designed to test the hypothesis that conjugates of CD4-mimetic miniprotein M48U1 and nnAbs specific for epitopes in the first and second constant (C1-C2) region of HIV-1 Env (A32-region or Cluster A epitopes) will develop into therapeutic antibodies (tAbs) capable of efficient reduction of the infected cell reservoir in infected individuals on ART thus develop into agents capable of a functional cure exclusively through FcR-effector mechanisms. This hypothesis will be tested using set of anti-Cluster A nnAbs which recognize highly conserved and functionally critical regions of gp120 which provide breadth of killing while minimizing the possibility of epitope escape. We have characterized these epitope targets at atomic and mapped them to the discontinuous sites involving highly conserved residues of the g120 inner domain. These regions in unliganded Env trimers are important for trimer stability and are inaccessible for antibody recognition until interactions of the Env spike with the cellular CD4 receptor. Our recent data indicate that exposure of these targets on the infected cell is limited by the low levels of surface CD4 that could effectively trigger Env trimers emerging on the cell surface. This represents a highly sophisticated mechanism put in place by HIV to prevent antibody-mediated clearance of virally infected cells. We were able to overcome the unfavorable exposure of these A32-region epitopes on infected cells with a CD4-mimetic molecule, the miniprotein M48U1 which binds within the CD4 binding site of Env trimers and triggers them to assume the CD4-bound conformation required to expose the A32-region epitopes on the surface of infected cells in the sera of HIV-1 infected individuals. Accordingly, by conjugating the M48U1 with the appropriate linker to the anti- Cluster A nnAbs we aim to develop new tAbs capable of sensitizing HIV-1-infected cells to ADCC-mediated killing. This effect will result from the cooperative action of the two moieties of conjugate. The M48U1 moiety will expose the A32-region within the Env trimer which will be subsequently recognized by the A32-region nnAb arm. Aim 1 is designed to develop mAb-M48U1 conjugates using lead mAbs of the A32-region region and evaluate their ability to recognize envelope epitopes and eliminate HIV-1-infected cells through ADCC responses in in vitro and ex-vivo experiments. Aim 2 will evaluate the ability of mAb-M48U1 conjugate to reduce the size of the latent HIV reservoir in ex-vivo “shock and kill” experiments using primary CD4+ T cells from ART-treated and untreated individuals. Pursuing our goal with A32-region conjugates, we expect to diminish the unfavorable impact of HIV-1 Nef- and Vpu-mediated CD4 down regulation that leads to reduction of CD4-inducible ADCC targets on infected cells and fully utilize the potential of nnAbs to kill the HIV-1 infected cells through ADCC. If successful, this project will add new weapons to the arsenal being built to achieve a functional cure in HIV-1- infected individuals.

项目概要/摘要 使用非中和抗体 (nnAb) 消除 HIV 感染细胞的功能性治愈策略 通过 Fc 受体 (FcR) 效应功能，包括抗体依赖性细胞毒性 (ADCC) 仍然是 重要但很大程度上尚未开发的研究途径。该项目旨在检验以下假设： CD4 模拟小蛋白 M48U1 和对第一和第二常数表位具有特异性的 nnAb 的缀合物 HIV-1 Env 的 (C1-C2) 区域（A32 区域或 A 簇表位）将发育成治疗性抗体 (tAb) 能够有效减少接受 ART 治疗的受感染个体中的受感染细胞库，从而发展为药物 能够完全通过 FcR 效应器机制进行功能性治愈，将使用该假设进行测试。 一组抗簇 A nnAb，可识别 gp120 的高度保守且功能关键的区域， 提供了杀伤的广度，同时表位逃逸的可能性我们已经表征了这些表位。 原子目标并将它们映射到涉及高度保守残基的不连续位点 g120 内部结构域在未配体的 Env 三聚体中对于三聚体稳定性很重要，并且 在 Env 尖峰与细胞 CD4 受体相互作用之前，无法进行抗体识别。 数据表明，这些目标在受感染细胞上的暴露受到表面 CD4 水平低的限制， 可以有效地触发细胞表面出现的 Env 三聚体，这代表了一种高度复杂的机制。 HIV 建立的机制可以防止抗体介导的病毒感染细胞的清除。 克服这些 A32 区表位在感染细胞上与 CD4 模拟分子的不利暴露， 微型蛋白 M48U1 结合在 Env 三聚体的 CD4 结合位点内，并触发它们呈现 CD4 结合构象需要暴露血清中感染细胞表面的 A32 区表位 因此，通过将 M48U1 与适当的接头缀合至抗 HIV-1 感染个体。 Cluster A nnAbs 我们的目标是开发能够使 HIV-1 感染细胞对 ADCC 介导的细胞敏感的新 tAbs 这种效应是由 M48U1 的两个部分的协同作用产生的。 暴露 Env 三聚体内的 A32 区域，随后将被 A32 区域 nnAb 臂识别。 目标 1 旨在使用 A32 区域的先导 mAb 开发 mAb-M48U1 缀合物并评估 它们识别包膜表位并通过 ADCC 反应消除 HIV-1 感染细胞的能力 体外和离体实验将评估 mAb-M48U1 缀合物减小尺寸的能力。 使用来自经 ART 处理和治疗的原代 CD4+ T 细胞进行离体“休克和杀伤”实验中的潜伏 HIV 储存库 我们希望通过 A32 区域缀合物来减少未经治疗的个体的不利影响。 HIV-1 Nef 和 Vpu 介导的 CD4 下调的影响导致 CD4 诱导型 ADCC 减少 靶向感染细胞，充分利用 nnAb 的潜力，通过 ADCC 杀死 HIV-1 感染细胞。 如果该项目取得成功，将为正在建设的武器库增添新的武器，以实现 HIV-1 的功能性治愈 感染者。