Accumulation of VH replacement products in HIV patients

描述(申请人提供)：中和抗体是针对细菌或病毒感染(包括艾滋病毒)的体液免疫反应的重要效应器。然而，在自然感染或常规疫苗方法中，很难诱导针对HIV的有效中和抗体反应。以前对HIV病毒基因组和包膜蛋白结构的研究表明，HIV已经进化出许多策略来避免中和抗体反应。最近对来自HIV精英控制者的中和抗体和抗gp120抗体的研究表明，这些抗体中的大多数是多反应的，在B细胞发育过程中通常不被容忍。VH替换通常被认为是一种受体编辑机制，以改变无功能的IgH基因或编码自身反应性抗体的IGH基因。我们发现，VH替代产品高度富含来自HIV患者浆母细胞的IgH基因，并且这些积累的VH替代产品中的大多数编码抗gp120和多反应抗体。此外，用gp120蛋白处理EU12 MHC+细胞可诱导BCR依赖的钙内流，并诱导VH替代。基于这些结果，我们假设HIV持续gp120抗原诱导HIV感染患者未成熟B细胞中的VH替换；所产生的表达VH替换产物的成熟B细胞在稍后的抗HIV反应中被阳性选择，以产生抗HIV和自身/多反应抗体。为了验证这一假设，(1)我们将确定VH替换产品是否在HIV患者中得到丰富；(2)我们将确定累积的VH替换产品是否编码抗HIV和自身/多反应抗体；(3)我们将确定在HIV患者的未成熟B细胞中是否诱导VH替换，并确定gp120是否诱导人类未成熟B细胞中的VH替换。我们将进一步确定BCR信号的调制是否会增强gp120诱导的VH替换。在抗HIV应答过程中，未成熟B细胞中VH替换的诱导和表达VH替换产物的成熟B细胞的阳性选择是HIV病毒抗原在慢性HIV感染中触发的两个不同的过程。了解潜在的机制将使我们能够调节VH的替代，并在未来的疫苗设计中促进产生有效的抗HIV抗体。

DESCRIPTION (provided by applicant): Neutralizing antibodies are important effectors in humoral immune responses against bacterial or viral infections, including HIV. However, it is difficult to elicit effective neutralizing antibody responses against HIV in natural infections or y conventional vaccine approaches. Previous studies of HIV viral genome and envelop protein structures have suggested that HIV has evolved many strategies to avoid neutralizing antibody responses. Recent studies of neutralizing antibodies and anti-gp120 antibodies derived from HIV elite controllers showed that most of these antibodies are polyreactive, which are not generally tolerated during B cell development. VH replacement is normally considered as a receptor editing mechanism to change non- functional IgH genes or IgH genes encoding autoreactive antibodies. We found that VH replacement products are highly enriched in IgH genes derived from plasmablasts of HIV patients and the majority of these accumulated VH replacement products encode anti-gp120 and polyreactive antibodies. Moreover, treatment of EU12 mHC+ cells with gp120 proteins induces Ca++ influx in a BCR dependent manner and also induces VH replacement. Based on these results, we hypothesize that persistent HIV gp120 antigens induce VH replacement in the immature B cells in HIV infected patients; the resulting mature B cells expressing VH replacement products are positively selected later during anti-HIV response to generate anti-HIV and self/polyreactive antibodies. To test this hypothesis, (1) we will determine if VH replacement products are enriched in HIV patients; (2) we will determine if the accumulated VH replacement products encode anti-HIV and self/polyreactive antibodies; (3) we will determine if VH replacement is induced in the immature B cells of HIV patients and determine if gp120 induces VH replacement in human immature B cells. We will further determine if modulation of BCR signaling enhances gp120 induced VH replacement. Induction of VH replacement in the immature B cells and positive selection of mature B cells expressing VH replacement products during anti-HIV response are two different processes triggered by HIV viral antigens during chronic HIV infection. Understanding the underlying mechanisms will allow us to regulate VH replacement and facilitate the generation of effective anti-HIV antibodies in future vaccine design.