B cell TLRs and germinal centers

 描述(由申请人提供)：体液免疫反应质量的决定因素，包括产生的抗体的大小和同种类型，以及亲和力成熟的程度，仍然定义不清，限制了合理疫苗设计的努力。虽然早期的研究表明B细胞的Toll样受体(TLRs)的天然免疫识别与快速低亲和力抗体反应有关，但我们最近的研究表明，TLR9或TLR7对B细胞的天然识别大大增强了生发中心(GC)反应的规模和效率，后者产生高质量的抗体。此外，在小鼠模型中，TLRs的这种新功能已被证明是对抗几种病毒感染的免疫防御所必需的。此外，越来越多的证据表明，在系统性红斑狼疮(SLE)小鼠模型中，TLR7和TLR9是产生抗核抗体所必需的关键成分。因此，TLRs促进高亲和力GC抗体应答的新途径可能对许多病毒的免疫防御和SLE的发展具有重要意义。最近的研究已经开始确定TLR识别增强免疫球蛋白应答的大小和质量的细胞基础，但这一调控的分子机制尚不清楚，这是本应用的主题。特定目的1旨在定义经TLR9刺激的GC B细胞与响应相同免疫但缺乏TLR信号组件MyD88的功能版本的GC B细胞相比，其mRNA和microRNA表达的变化。具体目标2将解决这样的假设，即基因表达的关键变化集中在GC B细胞的亚群中，即从滤泡辅助T细胞(TFH)接收选择信号和/或对抗原具有更高亲和力的GC B细胞。这个问题将通过微流控单细胞分析来评估，这些基因表达谱来自表达Myc-GFP报告的GC B细胞(由与TFH细胞的生产性相互作用产生)或来自对抗原具有确定亲和力的GC B细胞。了解这一过程的分子机制将有助于合理的疫苗设计，也为治疗SLE的治疗方法的开发提供了新的靶点。

 DESCRIPTION (provided by applicant): Determinants of the quality of a humoral immune response, including the magnitude and isotype of antibody produced, and the extent of affinity maturation, remain poorly defined, limiting efforts of rational vaccine design. Whereas earlier studies had implicated innate immune recognition by Toll-like receptors (TLRs) of B cells in rapid lower affinity antibody responses, our recent studies have shown that innate recognition by TLR9 or TLR7 of B cells strongly enhances the magnitude and the efficacy of the germinal center (GC) response, which generates high quality antibodies. Moreover, this novel function of TLRs has been shown to be required for immune defense against several virus infections in mouse models. In addition, accumulating evidence has indicated that TLR7 and TLR9 are critical components required for the production of anti-nuclear antibodies in mouse models of systemic lupus erythematosus (SLE). Thus, a new pathway whereby TLRs promote high affinity GC antibody responses is likely to be important for immune defense against many viruses and for development of SLE. Recent studies have begun to define the cellular basis by which TLR recognition enhances the magnitude and quality of the IgG response, but the molecular mechanisms underlying this regulation are unknown, which is the topic of this application. Specific Aim 1 is designed to define the changes in mRNA and microRNA expression in GC B cells experiencing stimulation via their TLR9 compared to GC B cells responding to the same immunization but lacking a functional version of the TLR signaling component MyD88. Specific Aim 2 will address the hypothesis that key changes in gene expression are concentrated in subsets of GC B cells, namely GC B cells that are receiving selection signals from follicular helper T cells (TFH) and/or have a higher affinity for antigen. This issue will be assessed by microfluidic single cell analysis of gene expression profiles from GC B cells expressing a Myc-GFP reporter (resulting from productive interaction with TFH cells) or from GC B cells of defined affinity for antigen. Understanding the molecular mechanisms of this process will be useful for rational vaccine design and also many provide new targets for development of therapies to treat SLE.