Development of a mouse model of peptidoglycan-induced pathology

描述（由申请人提供）：肽聚糖（PGN）是一种高度保守的病原体相关分子模式，在革兰氏阳性菌中含量特别高。人和非人灵长类动物在体外通过产生炎性细胞因子和血小板活化以及在体内通过全身性炎症和弥散性血管内凝血（DIC）对PGN作出反应。巧合的是，小鼠和小鼠细胞显示出对PGN的最小反应。我们最近发现，人类和非人类灵长类动物都天然表达IgG抗体，这些抗体与来自各种病原体的PGN交叉反应，而小鼠缺乏这些抗体。基于以下观察，抗PGN抗体对于PGN应答是必需的：1.所有调查的健康人表达调理PGN的抗PGN抗体。2. PGN激活人血清和血浆中的经典补体途径。3.正常人IgG的完整但非F（ab '）2片段支持人先天免疫细胞中PGN触发的炎性细胞因子产生。4.人IgG受体Fc？HEK 293细胞中的RIIa允许细胞以人IgG依赖性方式结合和吞噬PGN。5.狒狒对PGN的体内挑战作出反应，具有全身炎症和DIC的特征;该反应与其抗PGN IgG抗体的个体滴度直接相关。我们假设抗PGN IgG的存在和水平与PGN引起的病理学相关，从而与革兰氏阳性病原体相关。本项目将直接检测人体中抗PGN IgG的存在是否通过将含有抗PGN抗体的人IgG被动转移至人Fc而导致PGN的致病作用？RIIA转基因小鼠。我们还将通过使小鼠对PGN免疫，体内挑战免疫或幼稚小鼠，并测量炎症体征，来产生PGN诱导的病理学的小鼠模型。小鼠模型将是一个重要的突破，因为它将允许更好地了解对PGN病原体相关分子模式的反应，所有革兰氏阳性病原体都有这种反应。

DESCRIPTION (provided by applicant): Peptidoglycan (PGN) is a highly-conserved pathogen-associated molecular pattern that is present in especially high amounts in Gram-positive bacteria. Humans and non-human primates respond to PGN in vitro by production of inflammatory cytokines and platelet activation and in vivo by systemic inflammation and disseminated intravascular coagulation (DIC). Paradoxically, mice and mouse cells show minimal responses to PGN. We recently discovered that both humans and non-human primates naturally express IgG antibodies that cross-react with PGN derived from a variety of pathogens, while mice lack these antibodies. The anti-PGN antibodies were essential for PGN responses, based on the following observations: 1. All surveyed healthy humans express anti-PGN antibodies that opsonize PGN. 2. PGN activates the classical complement pathway in human serum and plasma. 3. Intact but not F(ab')2 fragments of normal human IgG support PGN-triggered inflammatory cytokine production in human innate immune cells. 4. Expression of the human IgG receptor Fc?RIIa in HEK293 cells permitted the cells to bind and phagocytose PGN in a human IgG-dependent manner. 5. Baboons responded to an in vivo challenge of PGN with features of systemic inflammation and DIC; the response directly correlated with their individual titer of anti-PGN IgG antibodies. We hypothesize that the presence and level of anti-PGN IgG is associated with the pathology caused by PGN and thus of Gram-positive pathogens. This project will directly test whether the presence of the anti-PGN IgG in humans contributes to the pathogenic effects of PGN by passive transfer of human IgG containing anti-PGN antibodies to human Fc?RIIA-transgenic mice. We will also generate a mouse model for PGN-induced pathology by making mice immune to PGN, challenging immune or naive mice in vivo, and measuring signs of inflammation. A mouse model will be an important breakthrough as it will permit a better understanding of the response to the PGN pathogen-associated molecular pattern, shared by all Gram-positive pathogens.