Small molecule activation of innate immunity by Listeria monocytogenes

描述（由申请人提供）：细胞内病原体对宿主免疫和医疗干预构成独特挑战，使此类病原体成为当代人类健康负担最大的病原体之一。单核细胞增生李斯特菌是一种革兰氏阳性的细胞内病原体，它激活两种不同的先天免疫途径，这两种途径由感染细菌的细胞内位置（噬菌体或胞质）来描述。对胞质细菌的独特反应导致了胞质监视途径（CSP）的假设，其能够识别损害胞质的病原微生物。该途径的激活导致IFN-2的产生，并已在多种细胞内病原体中得到证实，包括M。tuberculosis，F. tularensis，L. pneumophila、布鲁氏菌和T.克鲁兹活的、复制的细胞内微生物的检测依赖于结合微生物配体的宿主受体。目前，我们缺乏对宿主受体和微生物配体参与先天性免疫检测的了解。单核细胞增多症，以及这类的许多其他病原体。详细分析了L.单核细胞增多症显示IFN-2的产生几乎完全依赖于多药物转运蛋白MdrM的存在。基于此，我们假设存在能够激活CSP的细菌衍生的小分子。目前，我们已经从L.单核细胞增多症，可以直接激活CSP。不能产生这种配体的细菌将用于表征其在细胞培养和鼠感染模型中的发病机制中的作用。此外，使用各种宿主菌株将允许表征在感染期间由该配体激活的先天免疫途径。最后，我们将使用固定化配体来鉴定相互作用的宿主蛋白，目的是确定宿主受体。细胞培养模型将用于验证已鉴定的配体相互作用蛋白。 公共卫生相关性：鉴于先天性免疫在人类疾病中的重要作用以及先天性免疫激活产生的细胞因子所引起的强有力的应答，详细了解L。单核细胞增多症激活免疫系统可能会产生许多有前途的治疗方法。从L.单核细胞增多症和识别这些分子的宿主蛋白质将提供可被操纵以治疗各种形式的人类疾病的靶标，最明显的应用是新佐剂、治疗微生物感染和恶性肿瘤的疫苗以及用于癌症和病毒治疗的新型干扰素诱导疗法。

DESCRIPTION (provided by applicant): Intracellular pathogens pose a unique challenge to host immunity and medical intervention, making this class of pathogens one of the largest contemporary human health burdens. Listeria monocytogenes, a gram- positive, intracellular pathogen, activates two distinct innate immune pathways, delineated by the intracellular location (phagasomal or cytosolic) of infecting bacteria. A unique response to cytosolic bacteria has led to the hypothesis of a cytosolic surveillance pathway (CSP) capable of identifying pathogenic microbes that compromise the cytosol. Activation of this pathway leads to IFN-2 production and has been demonstrated with multiple intracellular pathogens, including M. tuberculosis, F. tularensis, L. pneumophila, Brucella, and T. cruzi. Detection of live, replicating intracellular microbes is dependent on host receptors that bind microbial ligands. Currently, we lack an understanding of the host-receptors and microbial-ligands involved in innate immune detection of L. monocytogenes, as well as many other pathogens of this class. Detailed analysis of CSP activation by L. monocytogenes showed that IFN-2 production is almost entirely dependent on the presence the multi-drug transporter MdrM. Based on this we hypothesized the presence of a bacterial derived small molecule able to activate the CSP. Now, we have purified and identified a novel ligand derived from L. monocytogenes that can directly activate the CSP. Bacteria that are unable to generate this ligand will be used to characterize its role in pathogenesis in both cell culture and murine models of infection. Furthermore, use of various host strains will allow for the characterization of the innate immune pathways activated by this ligand during infection. Finally, we will use immobilized ligand to identify interacting host proteins with the aim of determining the host receptor. Cell culture models will be used to validate identified ligand interacting proteins. PUBLIC HEALTH RELEVANCE: Given the important role of innate immunity in human disease and the potent response elicited by the cytokines generated from innate immune activation, a detailed understanding of the mechanism by which L. monocytogenes activates the immune system may give rise to many promising therapeutics. Immuno- modulating molecules from L. monocytogenes and the host proteins that recognize these molecules will provide targets that can be manipulated to treat various forms of human disease, with the most obvious applications toward new adjuvants, vaccines to treat microbial infection and malignancies, and novel interferon inducing therapies for cancer and viral treatment.