Regulation of humoral immunity in a mouse model of hookworm infection

全世界估计有7亿人感染钩虫，造成重大社会经济问题，并因儿童贫血、营养不良和发育迟缓对健康造成显著影响。虽然药物可以减轻蠕虫的负担，但由于再次感染，它们的效率往往很低，并可能导致耐药性的出现。目前还没有针对人类钩虫感染的疫苗。巴西尼波圆线虫（Nippostrongylus brasiliensis, Nb）是研究小鼠钩虫感染机制（包括保护性免疫途径）的常用实验室模型。Nb感染在肺和小肠引起强烈的2型免疫反应，伴有明显的嗜酸性粒细胞增多、高IgE水平和Th2细胞和ILC2s的积累。本建议的重点是分析对Nb的体液免疫反应，特别是在继发性感染或单一Nb衍生蛋白免疫后。我们之前可以证明，在Nb感染期间，除了已知的类开关重组到IgE的功能外，B细胞还需要IL-4/ il -13诱导的转录因子STAT6来形成生发中心（GC）。我们进一步确定了B细胞中stat6调控的基因，我们现在将对这些基因进行功能表征，以揭示这些基因如何参与GC反应，浆细胞（PC）分化和记忆B细胞的形成。使用命运图方法，我们将确定记忆B细胞和pc在原发性和继发性Nb感染后的分化和持久性。我们还将分析命运定位细胞的B细胞受体（BCR）库，并确定单细胞中连接的BCR/转录组谱，以鉴定扩增克隆，从中克隆BCR并用于鉴定nb衍生抗原或产生BCR转基因小鼠。最近，我们发现了一种新的Nb衍生抗原，可提供针对Nb攻击感染的保护性免疫。这种保护作用发生在皮肤中，而在嗜碱性细胞缺乏的小鼠中则消失，这表明它需要抗体介导的嗜碱性细胞激活。对这种抗原的体液免疫反应的进一步表征可能导致未来针对蠕虫的新疫苗接种策略的发展。

Estimated 700 million people are affected by hookworm infections world-wide leading to major socioeconomic problems and a pronounced health impact caused by anemia, malnutrition and growth retardation of children. While medications can reduce worm burden they are often of low efficiency due to reinfections and may lead to the emergence of drug resistance. Vaccines are not yet available for human hookworm infections. The helminth Nippostrongylus brasiliensis (Nb) is a frequently used laboratory model to study the mechanisms of hookworm infections including pathways of protective immunity in mice. Nb infections elicit a strong type 2 immune response in the lung and small intestine with pronounced eosinophilia, high IgE levels and accumulation of Th2 cells and ILC2s. The focus of this proposal is the analysis of the humoral immune response to Nb especially after secondary infection or immunization with a single Nb-derived protein. We could previously show that during Nb infection the IL-4/IL-13-induced transcription factor STAT6 is required in B cells for germinal center (GC) formation in addition to its known function for class switch recombination to IgE. We further identified STAT6-regulated genes in B cells that we will now functionally characterize as part of this proposal to uncover how these genes may be involved in the GC response, plasma cell (PC) differentiation and formation of memory B cells. Using a fate-mapping approach, we will determine the differentiation and persistence of memory B cells and PCs after primary and secondary Nb infection. We will also analyze the B cell receptor (BCR) repertoire of fate-mapped cells and determine the linked BCR/transcriptome profile in single cells to identify expanded clones from which BCRs can be cloned and used to identify Nb-derived antigens or generate BCR-transgenic mice. Recently, we identified a new Nb-derived antigen that provides protective immunity against a Nb challenge infection. The protective effect occurs in the skin and is lost in basophil-deficient mice suggesting that it requires antibody-mediated activation of basophils. Further characterization of the humoral immune response to this antigen could lead to development of new vaccination strategies against helminths in the future.