Calprotectin modulates neutrophil function during Staphylococcus aureus infection of the heart

项目总结 2019年，耐甲氧西林金黄色葡萄球菌感染是近40万人住院的基础 每年，直接成本估计为17亿美元。此外，金黄色葡萄球菌是细菌的主要原因。 心内膜炎。了解宿主-病原体的相互作用会扭曲疾病的结果，这将有助于设计 有效的治疗策略。中性粒细胞具有抗菌功能，这对先天的 金黄色葡萄球菌的免疫反应。初步数据显示，中性粒细胞缺乏钙保护素(CP)，这是一种高度 中性粒细胞表达丰富的免疫蛋白，表现出线粒体动态平衡的改变，其中CP- 与野生型相比，缺乏中性粒细胞对金黄色葡萄球菌产生更多的线粒体超氧化物歧化酶 中性粒细胞。因此，CP缺陷的中性粒细胞会经历更高的自杀性网织红细胞增多。此外，增加了 自杀性网织红细胞增多症与CP缺陷小鼠心脏内细菌负荷较低有关 并提高了系统性金黄色葡萄球菌感染期间的存活率。这表明中性粒细胞和CP生物学是 在内心独一无二。目标1将确定为什么心脏在金黄色葡萄球菌期间为CP生物学提供了一个独特的生态位 感染。更具体地说，我们将解决(I)CP缺陷小鼠的心肌细胞功能是否发生改变， 从而扭曲中性粒细胞的反应，以及(Ii)确定中性粒细胞分泌/滞留CP的驱动因素 在心脏感染期间。这些实验意义重大，因为它们定义了免疫学和新陈代谢 心脏环境与其他感染部位的比较，以及这对CP和中性粒细胞的影响 生物学。目的2将重点介绍细胞内CP在改变线粒体动态平衡中的作用。我们将具体地 测试CP在调节线粒体代谢和金属动态平衡中的作用，以及下游对此的影响 对中性粒细胞功能有影响。这些实验意义重大，因为它们确定了CP是一种分子变阻器 通过控制线粒体动态平衡来发挥中性粒细胞的功能，这可能广泛适用于其他细胞 炎症时表达CP。这一建议为CP的功能提供了关键的科学见解， 作为治疗心脏金黄色葡萄球菌感染的生物靶点，可能特别有效。此外， 该提案实现的技术进步将创建一个可应用于其他 炎症性疾病。

PROJECT SUMMARY In 2019, methicillin-resistant Staphylococcus aureus infections were the basis of nearly 400,000 hospitalizations per year with direct costs estimated at $1.7 billion. Furthermore, S. aureus is the leading cause of bacterial endocarditis. Understanding host-pathogen interactions that skew disease outcome will facilitate the design of efficacious therapeutic strategies. Neutrophils possess antimicrobial functions that are critical to the innate immune response to S. aureus. Preliminary data show that neutrophils lacking calprotectin (CP), a highly abundant immune protein expressed by neutrophils, exhibit altered mitochondrial homeostasis, where CP- deficient neutrophils produce more mitochondrial superoxide in response to S. aureus compared to wild-type neutrophils. As a result, CP-deficient neutrophils undergo elevated suicidal NETosis. In addition, increased suicidal NETosis correlates with CP-deficient mice having lower bacterial burdens specifically within the heart and increased survival during systemic S. aureus infection. This suggests that neutrophil and CP biology is unique within the heart. Aim 1 will identify why the heart offers a unique niche for CP biology during S. aureus infection. More specifically, we will address (i) whether cardiomyocyte function in CP-deficient mice is altered, thereby skewing the neutrophil response and (ii) identify factors driving CP secretion/retention by neutrophils during infection in the heart. These experiments are significant as they define the immunological and metabolic environment of the heart, compared to other sites of infection, and the implications this has on CP and neutrophil biology. Aim 2 will focus on the role of intracellular CP in altering mitochondrial homeostasis. We will specifically test the role of CP in regulating mitochondrial metabolism and metal homeostasis, and downstream impacts this has on neutrophil function. These experiments are significant because they identify CP as a molecular rheostat for neutrophil function by controlling mitochondrial homeostasis, which may be broadly applicable to other cells expressing CP during inflammation. This proposal provides critical scientific insights into the function of CP that may be especially efficacious as a biological target for treating S. aureus infections of the heart. In addition, the technological advancements achieved by this proposal will create a platform that can be applied to other inflammatory diseases.