The Immunology of Recurrent Group A Streptococcus Tonsillitis

摘要 复发性气性扁桃体炎或链球菌性咽喉炎是儿科常见病。扁桃体炎复发病史(RT) 提示转诊做扁桃体切除术。为什么只有一些孩子得了链球菌性咽喉炎，这是一个长期存在的谜团。至 回答这个问题，我们发展了一组儿童，他们接受了扁桃体切除术， 由于气体或非RT原因。我们收集了216个扁桃体，以确定RT儿童是否有 扁桃体生发中心(GC)对GAS的反应受损，容易反复感染。 扁桃体生发中心内是GC T滤泡辅助细胞(TFH)，是一种特化的CD4T细胞，它可以 为GC B细胞提供帮助，指导亲和力成熟、体细胞高度突变的记忆B细胞的发育 细胞和抗体。在我们的队列中，我们观察到RT扁桃体具有明显较小的生发中心 GcTfh和GcB细胞明显减少。我们鉴定出‘At Risk’人类白细胞抗原II类等位基因使人联想到‘At Risk’ 中毒性休克综合征和风湿性心脏病的等位基因，这是一种未经治疗的链球菌咽喉炎的不良后遗症。 使用我们的新的活的CD4T细胞试验来鉴定GAS特异性的GC Tfh细胞，我们发现RT扁桃体具有 对气体特异性GC-TFH细胞形成的偏见。有趣的是，由于我们有配对的血液样本，我们 观察到针对一种关键气体毒力因子链球菌的循环抗体显著减少 热源性外毒素A(SPEA)，临床上与侵入性气体易感性相关的低滴度 疾病。最后，我们鉴定了SPEA诱导的具有细胞溶解功能的颗粒酶B-GC-Tfh细胞 活性，我们称之为‘杀伤Tfh’细胞。这些“杀手Tfh”细胞可能解释了 RT扁桃体。我们假设RT儿童对反复发生的气体感染具有免疫敏感度。 在这里，我们将测试与这种易感性相关的特定假设，重点是宿主对GAS的反应 评估我们已确定的“风险”HLA等位基因的作用以及GAS抑制获得性免疫的能力 通过诱导“杀伤Tfh”细胞进行反应。 这项K08提案，如果得到资助，将支持我成为一名独立的内科科学家的目标。 在培训期间，我将学习人类免疫学的先进技术，获得 生物信息学和统计分析，并将这些技能应用于翻译研究项目。拉荷亚 过敏和免疫学研究所(LJI)为拟议的研究提供了一个合作环境。我的 导师Shane Crotty和共同导师Victor Nizet都是各自领域的世界知名专家 生发中心和TFH细胞生物学与GAS感染。这个项目将让我继续我的发展 作为一名内科科学家，将人类免疫学的先进技术应用于临床 有问题。

Abstract Recurrent GAS tonsillitis or strep throat is a common pediatric disease. A history of recurrent tonsillitis (RT) prompts a referral for tonsillectomy. It is a long-standing mystery why only some children get strep throat. To answer this question, we developed a cohort of children who had undergone tonsillectomies for either RT due to GAS or non-RT reasons. We have accrued 216 tonsils to determine whether children with RT have an impaired tonsillar germinal center (GC) response to GAS, predisposing them to recurrent infection. Within the tonsillar germinal center are GC T follicular helper (Tfh) cells, specialized CD4+ T cells that provide help to GC B cells to instruct the development of affinity matured, somatically hypermutated memory B cells and antibodies. In our cohort, we observed that RT tonsils have significantly smaller germinal centers with significantly fewer GC Tfh and GC B cells. We identified `At Risk' HLA Class II alleles reminiscent of `At Risk' alleles for toxic shock syndrome and rheumatic heart disease, an adverse sequellae of untreated strep throat. Using our novel live CD4+ T cell assay to identify GAS-specific GC Tfh cells, we discerned that RT tonsils have a bias against GAS-specific GC Tfh cell formation. Intriguingly, as we have paired blood specimens, we observed significantly fewer circulating antibodies against a critical GAS virulence factor streptococcal pyrogenic exotoxin A (SpeA), with a lower titer clinically associated with a predisposition for invasive GAS disease. Finally, we have identified aberrant SpeA-induced granzyme B+ GC Tfh cells endowed with cytolytic activity, which we refer to as `killer Tfh' cells. These `killer Tfh' cells may explain the smaller germinal centers in RT tonsils. We hypothesize that children with RT have an immunosusceptibility to recurrent GAS infections. Herein, we will test specific hypotheses related to this predisposition, focusing on the host response to GAS by evaluating the role of `At Risk' HLA alleles we have identified and GAS's ability to quench an adaptive immune response by inducing `killer Tfh' cells. This K08 proposal, if funded, will support me in my goal to become an independent physician-scientist. During the training period, I will learn advance techniques in human immunology, acquire expertise in bioinformatics and statistical analyses, and apply these skills to translational research projects. La Jolla Institute for Allergy and Immunology (LJI) provides a collaborative environment for the proposed studies. My mentor Shane Crotty and co-mentor Victor Nizet are both world-renowned experts in their respective fields of germinal center and Tfh cell biology and GAS infections. This project will allow me to continue my development as a physician-scientist by applying advanced techniques in human immunology to addressing clinical problems.