Human in vivo Th17 cell responses in cutaneous immunity to Staphylococcus aureus

项目摘要/摘要 社区获得性耐甲氧西林金黄色葡萄球菌的流行现状 二十年来，出现了毒力强和多重耐药的菌株，这些菌株正在引起严重的 医院外健康人的皮肤感染。这些感染正在造成严重的公共卫生 令人担忧的是，尤其是在CA-MRSA临床分离株的抗生素耐药性持续上升的情况下。我们的终极 目标是深入了解特定的人类免疫反应，以达到更有效的目标 预防金黄色葡萄球菌皮肤感染的疫苗接种策略。这一点尤其重要，因为所有的疫苗接种 迄今为止在临床前小鼠模型中有效的针对金黄色葡萄球菌的尝试都没有 对人类有效或实际上加剧了感染。中性粒细胞在感染部位的募集 促进脓肿的形成，是清除金黄色葡萄球菌皮肤感染所必需的。因此，在这项提案中， 我们将重点关注人类Th17细胞和反应，因为它们代表抗原特异性的适应性反应 这可能会控制PMN的招募。然而，人类机制研究的一个主要障碍是 中性粒细胞募集是缺乏一个体内模型系统与正常的人中性粒细胞数量。当前 人源化的小鼠模型只有1%-5%的循环中人中性粒细胞-远远低于45%-70%的 在人类血液中发现的中性粒细胞。为了克服这一点，我们将开发出更高效的人性化小鼠 中性粒细胞重建来验证我们的总体假设，即人类Th17细胞细胞因子IL-17A，IL-22和 IL-26可通过诱导中性粒细胞募集来促进金黄色葡萄球菌皮肤感染的清除。我们进一步 假设金黄色葡萄球菌特异性的CD4+T细胞，特别是Th17细胞可以促进中性粒细胞 招募和清除细菌。在目标1中，我们将确定人类IL-17A、 IL-22和IL-26促进中性粒细胞募集和宿主对金黄色葡萄球菌皮肤感染的防御 人性化的老鼠。在目标2中，我们将确定人类Th17细胞在促进PMN募集和 清除人源化小鼠的金黄色葡萄球菌皮肤感染。值得注意的是，我们的人性化老鼠模型将拥有 都匹配了人类皮肤和人类免疫细胞，这是高度创新的，因为这还没有 以前为了研究金黄色葡萄球菌皮肤感染而做的。综上所述，我们的提案将在体内提供新的 人类Th17细胞和细胞因子促进中性粒细胞募集和宿主的机制研究 防御金黄色葡萄球菌皮肤感染。假设我们的结果将使用优化的人性化 活体模型，我们的发现更有可能翻译到人类身上，并提供有关特定的关键信息 以人类免疫机制为靶点，在未来开发一种有效的金黄色葡萄球菌疫苗。

Project Summary / Abstract The epidemic of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) over the past two decades has resulted in the emergence of virulent and multi-drug resistant strains that are causing severe skin infections in healthy people outside of hospitals. These infections are creating a serious public health concern, especially since antibiotic resistance among CA-MRSA clinical isolates continues to rise. Our ultimate goal is to gain insights into the specific human immune responses that could be targeted for more effective vaccination strategies against S. aureus skin infections. This is especially important because all vaccination attempts against S. aureus to date that were previously effective in preclinical mouse models either had no efficacy in humans or actually exacerbated the infection. The recruitment of neutrophils to the site of infection facilitates abscess formation and is required for clearance of S. aureus skin infections. Thus, in this proposal, we will focus on human Th17 cells and responses since these represent antigen-specific adaptive responses that might control PMN recruitment. However, a major impediment to investigating the mechanisms of human neutrophil recruitment is the lack of an in vivo model system with normal human neutrophil numbers. Current humanized mouse models only possess 1-5% of circulating human neutrophils—far below the 45-70% of neutrophils found in human blood. To overcome this we will develop humanized mice with more efficient neutrophil reconstitution to test our overall hypothesis that the human Th17 cell cytokines IL-17A, IL-22 and IL-26 can promote clearance of a S. aureus skin infection by inducing PMN recruitment. We further hypothesize that S. aureus-specific CD4+ T cells, and in particular Th17 cells, can promote neutrophil recruitment and bacterial clearance. In Aim 1, we will determine the mechanisms by which human IL-17A, IL-22 and IL-26 promote neutrophil recruitment and host defense against a S. aureus skin infection in humanized mice. In Aim 2, we will determine the role of human Th17 cells in promoting PMN recruitment and clearing a S. aureus skin infection in humanized mice. Of note, our humanized mouse models will possess both “matched” human skin and human immune cells, which is highly innovative because this has not been done before to study S. aureus skin infections. Taken together, our proposal will provide new in vivo mechanistic insights by which human Th17 cells and cytokines promote neutrophil recruitment and host defense against S. aureus skin infections. Given that our results will be obtained using optimized humanized in vivo models, our findings are more likely to translate to humans and provide key information about the specific human immune mechanisms to target in the future development of an effective S. aureus vaccine.