Mechanistic studies of BLyS-mediated modulation in HIV-1 Env-specific antibody responses

BLyS 介导的 HIV-1 Env 特异性抗体反应调节机制研究

• 批准号: 9010936
• 负责人: Michael Paul Cancro
• 金额: $ 69.56万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-10 至 2020-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9010936
• 关键词: Antibodies; Antibody Response; B-Cell Activation; B-Cell Development; B-Lymphocyte Subsets; B-Lymphocytes; Binding; Cell Maturation; Cells; Clone Cells; Development; Disadvantaged; Frequencies; HIV; HIV vaccine; HIV-1; Health; Immune response; Immunization; Immunoglobulin Somatic Hypermutation; Immunoglobulin Variable Region; Macaca mulatta; Mediating; Memory B-Lymphocyte; Mus; Mutate; Pattern; Positioning Attribute; Prophylactic treatment; Reaction; Recruitment Activity; Research; Sorting - Cell Movement; Specificity; Staging; Structure of germinal center of lymph node; TALL-1 protein; Testing; Vaccination; Work; cytokine; env Gene Products; improved; in vivo; neutralizing antibody; nonhuman primate; prophylactic; response

 DESCRIPTION (provided by applicant): Despite quantitatively robust humoral immune responses to HIV-1, prophylaxis is rare because broadly neutralizing antibodies are uncommon after natural immunization or vaccination. Increasing evidence suggests this reflects the counterselection of B cells needed for broadly neutralizing responses at checkpoints imposed during B cell development or activation. These observations predict that relaxing B cell counterselection should alter the quality of HIV-specific responses and establish repertoires with prophylactic potential, but this prediction has not been directly tested. The cytokine BLyS modulates B cell selection at two checkpoints: first at the transitional to mature preimmune B cell developmental step; and then among activated B cells in the germinal center. Importantly, treating mice with BLyS prior to HIV-1 envelope immunization yields an increased frequency of mice responding with broader neutralizing activity. Together, these observations position us for detailed study of how relaxed selection at the transitional and/or germinal center checkpoints impacts the ability to mount broadly neutralizing responses. In Aim 1, we will determine whether relaxing transitional selection with BLyS establishes a preimmune repertoire more capable of broad neutralization. We will accomplish this through analyses of repertoire composition and diversity in the transitional, follicular and marginal zone B cell subsets, followed by single-cell cloning and re-expression of antibodies to assess HIV neutralizing capacity. In Aim 2, we will use a similar strategy to determine whether surplus BLyS alters germinal center selection, and allows somatically mutated germinal center B cells capable of broadly neutralizing responses to persist and enter memory B cell pools. We will compare GC and memory B cells from mice treated with BLyS prior to immunization with Env, or from mice treated with exogenous BLyS in the early stages of GC formation after Env immunization. In Aim 3, we will extend our findings to nonhuman primates, by determining whether rhesus macaques show similar enlargement of TR and FO pools after BLyS treatment, and whether BLyS treatment prior to Env vaccination improves neutralizing antibody breadth.

 描述（由申请人提供）：尽管对 HIV-1 的体液免疫反应在数量上强劲，但预防措施很少见，因为自然免疫或疫苗接种后广泛中和的抗体并不常见。越来越多的证据表明，这反映了 B 细胞的反选择，需要在 B 细胞发育或激活过程中施加的检查点处广泛中和反应。这些观察结果预测，放松 B 细胞反选择应该会改变 HIV 特异性反应的质量，并建立具有预防潜力的方案，但这一预测尚未得到直接检验。细胞因子 BLyS 在两个检查点调节 B 细胞选择：首先是在向成熟免疫前 B 细胞发育的过渡阶段；然后是生发中心激活的 B 细胞。重要的是，在 HIV-1 包膜免疫之前用 BLyS 治疗小鼠可以增加小鼠响应更广泛的中和活性的频率。总之，这些观察结果使我们能够详细研究过渡和/或生发中心检查点的宽松选择如何影响广泛中和反应的能力。在目标 1 中，我们将确定使用 BLyS 放松过渡选择是否建立了更能够广泛中和的免疫前库。我们将通过分析移行、滤泡和边缘区 B 细胞亚群的库组成和多样性来实现这一目标，然后分析单细胞 克隆和重新表达抗体以评估 HIV 中和能力。在目标 2 中，我们将使用类似的策略来确定过剩的 BLyS 是否会改变生发中心选择，并允许体细胞突变的生发中心 B 细胞能够广泛中和反应，从而持续存在并进入记忆 B 细胞池。我们将比较 Env 免疫前用 BLyS 处理的小鼠的 GC 和记忆 B 细胞，或 Env 免疫后在 GC 形成早期阶段用外源 BLyS 处理的小鼠的 GC 和记忆 B 细胞。在目标 3 中，我们将通过确定恒河猴在 BLyS 治疗后是否表现出类似的 TR 和 FO 池扩大，以及 Env 疫苗接种之前的 BLyS 治疗是否改善中和抗体广度，将我们的发现扩展到非人类灵长类动物。