Dissecting The Interplay of GM-CSF and Neutrophils In IgG and IgA Responses

该建议的目的是阐明佐剂GM-CSF增强疫苗诱导的针对SIV的IgG和伊加应答的机制。这些研究将利用该联盟提供的独特资源以及阿马拉和Pulendran小组的互补和综合专业知识，评估用于诱导中和抗体（NAb）的新型Env免疫原（项目1和项目2）。Ahmed/Silvestri/Crotty小组，探索T细胞对Ab反应的调节（项目3）。Cerutti小组，研究先天免疫细胞对B细胞的调节（项目4）。B细胞通过产生NAb包封病毒表面的Env刺突来提供针对HIV的免疫保护。然而，引发稳健和持续的NAb应答仍然是一个主要障碍，因为Env是NAb诱导的唯一相关抗原，其特征在于序列变异、有限的抗原性和稀缺的免疫原性。另一个障碍涉及缺乏能够有效诱导NAb的策略，既全身性的，并在粘膜部位的进入。来自阿马拉小组的初步数据显示，GM-CSF增强了全身淋巴器官中产生的疫苗诱导的SIV反应性IgG抗体的亲合力和频率，并促进肠道分泌物中SIV特异性伊加的释放。这些作用与增加对肠道挑战的保护相关。在这个建议中，我们假设GM-CSF动员和激活一个独特的脾IL-21产生NBH中性粒细胞的子集配备了B细胞辅助功能。我们认为，NBH细胞通过诱导IG重链类别转换、V（D）J基因体细胞超突变和脾B细胞（包括边缘区和记忆B细胞）中的肠道归巢受体来增强针对SIV的全身IgG和肠道伊加应答。提出了三个目标。目的1：阐明GM-CSF诱导脾B细胞IgG和伊加类转换的机制。目的二是探讨GM-CSF诱导脾伊加类转换B细胞归巢的机制。目的3是确定GM-CSF提高疫苗诱导的全身IgG和肠道伊加对SIV的亲和力的机制。

The goal of this proposal is to elucidate the mechanisms by which the adjuvant GM-CSF enhances vaccine induced IgG and IgA responses against SIV. These studies will take advantage ofthe unique resources made available by this consortium and ofthe complementary and integrative expertise ofthe Amara and Pulendran groups, which evaluate novel Env immunogens for the induction of neutralizing Abs (NAbs) (Project 1 and Project 2). the Ahmed/Silvestri/Crotty group, which explores the regulation of Ab responses by T cells (Project 3). and the Cerutti group, which studies the regulation of B cells by innate immune cells (Project 4). B cells provide immune protection against HIV by producing NAbs to envelope (Env) spikes on the surface ofthe virus. However, eliciting robust and sustained NAb responses remains a major obstacle, because Env, the only relevant antigen for NAb induction, is characterized by sequence variation, limited antigenicity and scarce immunogenicity. An additional obstacle relates to the lack of strategies capable of effectively inducing NAbs both systemically and at mucosal sites of entry. Preliminary data from the Amara group show that GM-CSF enhances the avidity and frequency of vaccine-induced SIV-reactive IgG Abs produced in systemic lymphoid organs and elicits release of SIV-specific IgA in intestinal secretions. These effects correlate with increased protection against an intestinal challenge. In this proposal we hypothesize that GM-CSF mobilizes and activates a unique subset of splenic IL-21-producing NBH neutrophils equipped with B cell helper function. We contend that NBH cells enhance systemic IgG and intestinal IgA responses against SIV by inducing Ig heavy chain class switching, V(D)J gene somafic hypermutation and gut-homing receptors in splenic B cells, including marginal zone and memory B cells. Three aims are proposed. Aim 1 is to elucidate the mechanism by which GM-CSF induces IgG and IgA class switching in splenic B cells. Aim 2 is to dissect the mechanism by which GM-CSF induces intestinal homing of splenic IgA class-switched B cells. Aim 3 is to determine the mechanism by which GM-CSF improves the avidity of vaccine-induced systemic IgG and intestinal IgA responses against SIV..