Engineering the innate immune response to Staphaureus infection

摘要 金黄色葡萄球菌(SA)是引起皮肤感染的主要原因。致命的 社区获得性耐甲氧西林金黄色葡萄球菌(MRSA)是最常见的皮肤来源 以及美国医院的软组织感染。迅速招募中性粒细胞 感染部位有足够数量的中性粒细胞(PMN)是控制感染的关键 耐甲氧西林金黄色葡萄球菌感染和防止扩散到重要器官。没想到，我们最近 发现造血干细胞和祖细胞(HSPC)也被招募来 伤口，这些细胞检测细菌抗原和毒力因子，并增强 解决耐甲氧西林金黄色葡萄球菌感染伤口所需的PMN数量。信令流程 诱导创面内HSPC髓系募集和分化增加 被发现涉及Toll样受体2(TLR2)检测来自于 革兰氏阳性细胞壁，并在伤口内释放。我们建议这一新的 已发现的宿主免疫特征是一种有效克服免疫的适应 耐甲氧西林金黄色葡萄球菌毒力因子如α-溶血素毒素(AT)对中性粒细胞的抑制作用 通过裂解血管周围巨噬细胞帮助引导它们到 感染。这一提议的核心假设是免疫调节 调整中性粒细胞数量和抗菌活性可加速MRSA感染 清除和治愈。这项提议将利用我们创新的伤口感染模型 使用基因工程生物发光细菌和转基因溶菌酶- M-EGFP敲入小鼠，产生荧光成熟的PMN。这款车型将是 与先进的活体整体动物光学成像结合使用，以无创 并纵向监测细菌负荷和免疫反应。翻译目标 将CD34用于实施HSPC髓系扩增的评价 局部扩增中性粒细胞对抗耐甲氧西林金黄色葡萄球菌感染的治疗潜力 免疫缺陷(NSG)小鼠创伤模型。

ABSTRACT Staphylococcus aureus (SA) is a major cause of cutaneous infections. Virulent community-acquired methicillin-resistant SA (MRSA) is the most common source of skin and soft tissue infections in U.S. hospitals. Prompt recruitment of polymorphonuclear (PMN) leukocytes in sufficient numbers to the site of infection is critical for controlling MRSA infection and preventing dissemination to vital organs. Unexpectedly, we recently discovered that hematopoietic stem and progenitor cells (HSPCs) are also recruited to wounds, and these cells detect bacterial antigens and virulence factors, and augment PMN numbers necessary to resolve a MRSA infected wound. The signaling process eliciting an increase in myeloid recruitment and differentiation of HSPC within the wound was found to involve toll-like receptor 2 (TLR2) detection of peptidoglycans derived from the gram-positive cell wall and released within the wound. We propose that this newly discovered host immune trait is an adaption to effectively overcome immune suppression by MRSA virulence factors such as α-hemolysin toxin (AT) that blocks PMN recruitment by lysing perivascular macrophages that help guide them to sites of infection. The central hypothesis governing this proposal is that immune-modulation that tunes PMN number and antibacterial activity against MRSA infection can hasten clearance and healing. This proposal will utilize our innovative model of wound infection that employs genetically-engineered bioluminescent bacteria and a transgenic lysozyme- M-EGFP knock-in mouse that produces fluorescent mature PMN. This model will be used in conjunction with advanced in vivo whole animal optical imaging to noninvasively and longitudinally monitor bacterial burden and immune responses. A translational goal will be the implementation of human CD34+ HSPC myeloid expansion to evaluate the therapeutic potential of local PMN expansion to combat MRSA infection in an immunodeficient (NSG) mouse wound model.