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

该提案的目的是阐明佐剂 GM-CSF 增强疫苗诱导的针对 SIV 的 IgG 和 IgA 反应的机制。这些研究将利用该联盟提供的独特资源以及 Amara 和 Pulendran 小组的互补和综合专业知识，评估用于诱导中和抗体 (NAbs) 的新型 Env 免疫原（项目 1 和项目 2）。 Ahmed/Silvestri/Crotty 小组，探索 T 细胞对抗体反应的调节（项目 3）。以及 Cerutti 小组，该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 来包膜病毒表面的尖峰 (Env)，从而提供针对 HIV 的免疫保护。然而，引发强劲且持续的 NAb 反应仍然是一个主要障碍，因为 Env 是 NAb 诱导的唯一相关抗原，其特点是序列变异、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在系统和粘膜进入位点有效诱导 NAb 的策略。 Amara 小组的初步数据表明，GM-CSF 增强了疫苗诱导的系统淋巴器官中产生的 SIV 反应性 IgG 抗体的亲合力和频率，并引起肠道分泌物中 SIV 特异性 IgA 的释放。这些作用与增强对肠道挑战的保护有关。在该提议中，我们假设 GM-CSF 动员并激活具有 B 细胞辅助功能的脾脏产生 IL-21 的 NBH 中性粒细胞的独特子集。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 IgA 反应。提出了三个目标。目标 1 是阐明 GM-CSF 诱导脾 B 细胞中 IgG 和 IgA 类别转换的机制。目标 2 是剖析 GM-CSF 诱导脾 IgA 类别转换 B 细胞肠道归巢的机制。目标 3 是确定 GM-CSF 提高疫苗诱导的针对 SIV 的全身 IgG 和肠道 IgA 反应的亲合力的机制。

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..