Long-lived B cell Immunity in the Respiratory Tract

描述（由申请人提供）：呼吸道感染在局部诱导强烈和持久的体液免疫反应，显著促进免疫保护免受侵袭性感染。诱导和控制保护性局部免疫反应的机制目前尚不完全清楚。这项研究是基于小鼠的初步数据，这些数据暗示在流感病毒感染后，快速诱导的滤泡外局灶B细胞反应是呼吸道长期体液免疫的来源。本提案的目的是确定调节呼吸道流感病毒的这种长期局部抗体反应的机制。在Specific Aim #1中，将使用BLIMP-1报告小鼠和一种新开发的体外追踪流感血凝素特异性、c12id表达B细胞的系统，在野生型小鼠和缺乏生发中心形成的小鼠（SAP-/-小鼠）或滤泡外灶反应强的小鼠（灭活病毒递送后）中测量流感病毒感染后肺抗体分泌细胞的分化途径和保护能力。特异性目标#2将研究调节肺浆细胞前体向呼吸道迁移/保留的机制。他们将评估来自区域淋巴结的病毒特异性B细胞/浆细胞迁移的程度，以建立肺组织浆细胞池，并使用遗传筛选和定制的微流体设备，将确定整合素和趋化因子/受体负责在剪切应力下肺组织浆细胞的选择性积累和/或保留。特异性目标#3将使用基因表达研究来确定肺组织中浆细胞/前体的分化阶段，并使用BrDU标记研究来确定肺中抗体分泌细胞寿命的潜在机制。过继性转移研究将评估维持抗原和/或感染诱导的炎症信号的需要。这些研究将提供有关呼吸道中产生长期体液免疫反应的B细胞特征和发育途径的新信息，以及B细胞反应调控的基本知识，有助于疫苗设计的理论依据。

DESCRIPTION (provided by applicant): Respiratory tract infections induce strong and long-lasting humoral immune responses locally at the site, contributing significantly to immune protection from challenge infection. The mechanisms that induce and control protective local immune responses are currently not fully understood. The study is based on preliminary data in mice that implicate the rapidly induced extrafollicular foci B cell response as source for long-lived humoral immunity in the respiratory tract following influenza virus infection. The objective for this proposal is to identify the mechanisms that regulate this long-term local antibody response to influenza virus in the respiratory tract. In Specific Aim #1 the differentiation pathways and protective capacity of lung antibody-secreting cells following influenza virus infection will be measured in wildtype mice and in mice that lack formation of germinal centers (SAP-/- mice) or strong extrafollicular foci responses (following inactivated virus delivery) using BLIMP-1 reporter mice and a newly developed system for tracking of influenza hemagglutinin-specific, C12Id-expressing B cells ex vivo. Specific Aim #2 will study the mechanisms regulating the migration/retention of lung plasma cell precursors to the respiratory tract. They will assess the extent to which migration of virus-specific B cells/plasma cells from regional lymph nodes is required for the establishment of lung tissue plasma cell pools, and using genetic screening and a custom microfluidics device, will identify the integrins and chemokines/receptors responsible for the selective accumulation and/or retention of plasma cells the lung tissue under shear stress. Specific Aim #3 will use gene expression studies to determine the differentiation stage of plasma cells/precursors in the lung tissue and BrDU labeling studies to identify the mechanisms underlying the longevity of the antibody-secreting cells in the lung. Adoptive transfer studies will assess the requirements for antigen and/or infection-induced inflammatory signals for their maintenance. These studies will provide novel information on the characteristics and the B cell developmental pathways that generate the long-lived humoral immune responses in the respiratory tract, basic knowledge on B cell response regulation that can aid rationale vaccine design. PUBLIC HEALTH RELEVANCE: Protection from infections with influenza virus is contributed at least in part by antibody-secreting cells that establish in the lung following influenza virus infection. This study aims to understand how these cells are generated and what regulates their migration/maintenance in the lung. This basic information will provide potential avenues for rational vaccine design that aims to boost local/mucosal immune responses.