Modeling Entamoeba histolytica host-parasite interactions

溶组织内阿米巴宿主-寄生虫相互作用建模

• 批准号: 121785-2013
• 负责人: Chadee, Khrisendath
• 金额: $ 2.62万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=522205
• 关键词: Modeling; Entamoeba; histolytica; host; parasite

Entamoeba histolytica (Eh) is a colonic protozoan parasite where 99% of infections are non-invasive. How the innate immune system determines the pathogenicity and level of risk posed by Eh are unanswered questions in this host-parasite interaction. When Eh invades, it is a dead end for the parasite as cysts production ceases and may kill the host. Eh invasion stimulates interleukin IL-1ß inflammatory responses. Even though Eh components can also induce inflammation through Toll-like receptor activation, it does not recapitulate the aggressive inflammatory IL-1ß production towards live Eh. This indicates that the host senses Eh and that other pathogen sensing pathways are activated to induce inflammation. We recently identified that NLRP3 inflammasome is the molecular sensor controlling the rapid IL-1ß response to Eh. Inflammasomes are cytosolic multimeric complexes that can be activated by pathogens. As inflammasome activation only occurs following direct contact with Eh, we hypothesize that inflammasome activation is a central mechanism used by the innate immune system to discriminate the threat posed by invading parasites. The specific aims are: 1) to determine the molecular mechanism of inflammasome activation by Eh and, 2) to quantify the function of inflammasomes in regulating the magnitude of the inflammatory response. To investigate this, we will assess inflammasome activation in macrophages (mo) using defined pharmacological inhibitors of the NLRP3 pathway and in mo that are genetically deficient for inflammasome components. Mechanistic studies will be done to elucidate a role for phagocytosis and phagosome maturation. Other studies will investigate if the danger signal ATP can trigger the inflammasome by blocking the P2X7 receptor and by enzymatic depletion of extracellular ATP. Inflammasome activation will be visualized in real-time using confocal microcopy with caspase-1 probes. Studies will be verified in WT and genetically deficient mice for inflammasome components or following inhibition of the inflammasome pathway. These studies will quantify a mechanism to define how Eh is able to successfully colonize without evoking unwanted host inflammatory responses.

溶组织内阿米巴（Eh）是一种结肠原生动物寄生虫，其中99%的感染是非侵入性的。 先天免疫系统如何决定Eh的致病性和风险水平是宿主-寄生虫相互作用中尚未回答的问题。当Eh入侵时，它是寄生虫的死胡同，因为包囊生产停止并可能杀死宿主。 Eh侵袭刺激白细胞介素IL-1 β炎症反应。尽管Eh组分也可以通过Toll样受体激活诱导炎症，但它并不重现针对活Eh的侵袭性炎症性IL-1 β产生。 这表明宿主感知Eh，并且其他病原体感知途径被激活以诱导炎症。我们最近发现NLRP 3炎性小体是控制IL-1 β对Eh快速反应的分子传感器。 炎性小体是可以被病原体激活的胞质多聚体复合物。 由于炎性小体激活仅发生在与Eh直接接触后，我们假设炎性小体激活是先天免疫系统用于区分入侵寄生虫构成的威胁的中心机制。 具体目标是：1）确定Eh激活炎性小体的分子机制，2）量化炎性小体在调节炎症反应程度中的功能。 为了研究这一点，我们将使用NLRP 3途径的定义的药理学抑制剂评估巨噬细胞（mo）中的炎性小体激活，以及遗传上缺乏炎性小体组分的mo中的炎性小体激活。 将进行机制研究以阐明吞噬作用和吞噬体成熟的作用。 其他研究将调查危险信号ATP是否可以通过阻断P2 X7受体和酶促消耗细胞外ATP来触发炎性小体。 将使用具有半胱天冬酶-1探针的共聚焦显微镜实时观察炎性小体活化。将在WT和遗传缺陷小鼠中验证炎性体成分或抑制炎性体途径后的研究。 这些研究将量化一种机制，以确定Eh如何能够成功地定殖，而不会引起不必要的宿主炎症反应。