Inflammation and NLR Proteins in Leishmaniasis

描述(由申请人提供)： 利什曼原虫引起一系列人类疾病，其中最严重的是内脏利什曼病(VL)。VL是一种潜在的致命性疾病，寄生虫在宿主的网状内皮器官中传播，导致严重抑制宿主免疫反应的慢性耗竭综合征。沙蝇载体进入人体真皮后，其前鞭毛体形态被髓系来源的宿主细胞吞噬，在那里转化为专有的细胞内无鞭毛体。在整个慢性感染过程中，寄生虫主要作为专性细胞内寄生虫在组织巨噬细胞中存活。长期以来，人们一直认为利什曼原虫在哺乳动物宿主的感染过程中只存在于单核细胞来源的细胞中。现在很明显，寄生虫可以感染其他类型的髓系细胞。中性粒细胞和炎性单核细胞是第一批到达感染部位并内化利什曼原虫的细胞。这项应用的初步研究表明，在慢性进行性感染期间，LIC继续将髓系细胞招募到感染部位。在癌症或移植模型中，具有抑制功能的不同种类的未成熟髓系细胞被称为髓源性抑制细胞或MDSCs，它们被证明能抑制获得性免疫反应并调节巨噬细胞表型。在此，我们建议验证一种假设，即弥漫性Lic感染部位的髓系细胞具有抑制性表型。NLR蛋白是胞质蛋白，对病原体相关或危险相关的分子模式做出反应。一些NLR蛋白激活多蛋白炎症体复合体，导致Caspase-1的激活，IL-1�和IL-18的释放，以及强大的炎症反应。非炎症体形成的NLR蛋白也通过不同的机制影响宿主防御，其中许多机制尚不清楚。我们推测，慢性VL免疫抑制的部分原因是侵入寄生虫传播部位的髓系细胞，而NLR是Lic感染期间髓系细胞功能的关键决定因素。我们建议调查以下目标。目的#1.确定LIC定位部位的髓系细胞在整个感染过程中的分布。假设：在急性感染期间，成熟的中性粒细胞和炎性单核细胞渗入寄生虫接种部位，而粒细胞和单核细胞衍生的髓系抑制细胞(MDSCs)在慢性感染后定位于寄生虫传播部位。目的#2.在小鼠模型中确定NLR蛋白是加重还是改善内脏利什曼病的病程。假设：Nlrp10对于髓系细胞的募集是必不可少的，而Nlrp12是发展保护性的1型免疫反应所必需的。

DESCRIPTION (provided by applicant): The Leishmania species protozoa cause a spectrum of human diseases, the most severe of which is visceral leishmaniasis (VL). VL is a potentially fatal disease in which parasites disseminate throughout reticuloendothelial organs of the host, causing a chronic wasting syndrome with profound suppression of host immune responses. After being deposited in human dermis by the sand fly vector, the promastigote form of the parasite is taken up through phagocytosis by host cells of myeloid origin, where it transforms to the obligate intracellular amastigote form. Throughout chronic infection, parasites survive as obligate intracellular parasites primarily in tissue macrophages. It was long believed that Leishmania reside exclusively in cells of monocytic origin throughout infection of the mammalian host. It is now apparent that parasites infect other myeloid cell types. Neutrophils and inflammatory monocytes are the first cells to arrive at the infection site and internalize Leishmania. Preliminary studiesin this application demonstrate that Lic continue to recruit myeloid cells to the infection site throughout chronic progressive infection. Heterogeneous populations of immature myeloid cells with suppressive functions, called Myeloid Derived Suppressor Cells or MDSCs, have been shown to suppress adaptive immune responses and modulate macrophage phenotype in models of cancer or transplantation. We propose herein to examine that hypothesis that myeloid cells infiltrating the sites of disseminated Lic infection have a suppressive phenotype. The NLR proteins are cytosolic proteins that respond to either pathogen-associated or danger- associated molecular patterns. Some of the NLR proteins activate the multi-protein inflammasome complex, resulting in activation of caspase-1, release of IL-1� and IL-18, and a potent inflammatory response. The non-inflammasome forming NLR proteins also affect host defenses through varied mechanisms, many of which are yet ill-defined. We hypothesize that myeloid cells infiltrating the sites of parasite dissemination are responsible in part for the immunosuppression of chronic VL, and that NLRs are critical determinants of myeloid cell function during Lic infection. We propose to investigate the following aims. AIM #1. Identify myeloid cells infiltratin the sites of Lic localization throughout infection. Hypothesis: Mature neutrophils and inflammatory monocytes infiltrate the site of parasite inoculation during acute infection, whereas granulocytic and monocytic myeloid derived suppressor cells (MDSCs) localize to the sites of parasite dissemination once chronic infection is established. AIM #2. Determine whether NLR proteins exacerbate or ameliorate the course of visceral leishmaniasis in murine models. Hypothesis: Nlrp10 is essential for recruitment of myeloid cells, whereas Nlrp12 is required for the development of a protective type 1 immune response.