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

本提案的目的是阐明GM-CSF佐剂增强疫苗诱导的针对SIV的免疫球蛋白和免疫球蛋白A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小组互补和综合的专门知识，评估用于诱导中和抗体(NAB)的新型环境免疫原(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)。和Cerutti小组，他们研究先天免疫细胞对B细胞的调节(项目4)。B细胞通过在病毒表面产生针对包膜的nabs(Env)尖峰来提供对HIV的免疫保护。然而，由于Env是唯一与NAB诱导相关的抗原，具有序列变异、抗原性有限和免疫原性低的特点，因此激发强大和持续的NAB反应仍然是一个主要障碍。另一个障碍涉及缺乏能够有效地从系统和在进入粘膜部位诱导NAB的战略。来自Amara小组的初步数据显示，GM-CSF增强了疫苗诱导的SIV反应性免疫球蛋白抗体在全身淋巴器官中产生的亲和力和频率，并诱导肠道分泌物中SIV特异性IgA的释放。这些影响与增强对肠道挑战的保护有关。在这项建议中，我们假设GM-CSF动员并激活了一组独特的脾IL-21产生的NBH中性粒细胞，配备了B细胞辅助功能。我们认为NBH细胞通过诱导脾B细胞(包括边缘带B细胞和记忆B细胞)的Ig重链类转换、V(D)J基因体细胞突变和肠道归巢受体来增强系统的免疫球蛋白和肠道免疫球蛋白A应答。提出了三个目标。目的1阐明GM-CSF诱导脾B细胞免疫球蛋白G和免疫球蛋白A转换的机制。目的2分析GM-CSF诱导脾IgA类转换B细胞肠道归巢的机制。目的3确定GM-CSF增强疫苗诱导的SIV全身免疫球蛋白和肠道免疫球蛋白A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..