Pathogenesis of Trypanosoma cruzi infection

克氏锥虫感染的发病机制

基本信息

批准号：
8650941
负责人：
ROBERTO DOCAMPO
金额：
$ 37.29万
依托单位：
UNIVERSITY OF GEORGIA
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-09-03 至 2018-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8650941
关键词：
Abbreviations Acquired Immunodeficiency Syndrome Adverse drug effect Adverse effects Affect Animals Bacteria Blood Blood Circulation Cell membrane Cells Chagas Disease Coagulants Complex Cyclophosphamide Development Diphosphates Disease Dominant-Negative Mutation Drug Targeting EF Hand Motifs Enzymes Gene Dosage Genome Immunosuppression In Vitro Infection Inflammatory Insect Vectors Intestines Invaded Knock-out Laboratories Latin America Length Life Light Malaria Membrane Proteins Metabolic Pathway Molecular Chaperones Morbidity - disease rate Mus Osmolar Concentration Parasite Control Parasitemia Parasites Pathogenesis Pharmaceutical Preparations Polyphosphates Polyps Property Proteins Protons Rectum Role Surface Trypanosoma cruzi Trypanosomiasis Tuberculosis Vaccines Vacuole Virulence Factors disorder control in vivo inhibitor/antagonist inorganic phosphate kidney medulla mortality mouse model mutant overexpression pathogen prevent protein transport public health relevance pyrophosphatase research study trafficking trans-sialidase transmission process uptake vector

项目摘要

Abstract Morbidity and mortality associated with Chagas disease in Latin America exceed better-known conditions such as malaria, tuberculosis, or AIDS. Millions of people are affected by this trypanosomiasis. No vaccines are available to prevent this disease and drug treatments have serious side effects and are not completely effective. Survival of Trypanosoma cruzi in the mammalian hosts depends on the parasite's ability to infect host cells, reproduce, and live in the blood of the host long enough to warrant its transmission through a bloodsucking insect vector. Our aim is to investigate these survival mechanisms and their role in the pathogenesis of T. cruzi infection, and shed light into potential ways to control the disease. Survival of T. cruzi trypomastigotes in the blood of the mammalian host and in the intestine of the vector depends in great part on their ability to tolerate dramatic changes in osmolarity during their circulation through the kidney medulla of the mammalian host (1,300-1,400 mOsm/Kg) or their passage through the rectum of the insect vector (1,000 mOsm/Kg), and we have found that polyphosphate (polyP) and the contractile vacuole complex (CVC) have en essential role in their survival mechanisms. Recent results from our laboratory suggest that polyP and/or pyrophosphate (PPi) could also be involved in the pathogenesis of T. cruzi infection. To reduce polyP levels we overexpressed a degradative enzyme that hydrolyzes both PPi and polyP resulting in a dramatic decrease of PPi/polyP. Mutant trypomastigotes overexpressing the enzyme did not produce detectable parasitemias and in several experiments all infected animals survived an otherwise lethal infection. Mice infected with parasites deficient in PPi/polyP failed to develop parasitemia after immunosuppression with cyclophosphamide strongly suggesting that infection had been completely cleared. Our results underscore an important role for PPi/polyP in the pathogenesis of T. cruzi infection. PolyP has been shown to act as a virulence factor in bacteria but little is known on its role in eukaryotic pathogens, besides its pro-coagulant and pro-inflammatory activities. Survival within the mammalian host also depends on the ability of T. cruzi to invade different host cells, escape from the parasitophorus vacuole and replicate intracellularly. T. cruzi trans-sialidases have been demonstrated to have essential roles in these mechanisms. However, the main obstacle in assessing the function of trans-sialidases is that knockout parasites were never obtained due to the large number of gene copies scattered through the genome. We have found that trans-sialidases traffic through the contractile vacuole in their way to the plasma membrane, and that disruption of this traffic by interfering with their passage through the CVC results in parasites devoid of these proteins in their surface. The study of this trafficking mechanism and of ways to interfere with this traffic will contribute to the understanding of the pathogenesis of T. cruzi infection.

抽象的拉丁美洲与恰加斯病相关的发病率和死亡率超过了众所周知的情况例如疟疾、肺结核或艾滋病。数百万人受到这种锥虫病的影响。不疫苗可以预防这种疾病，药物治疗有严重的副作用，不能有效预防。完全有效。克氏锥虫在哺乳动物宿主中的存活取决于寄生虫的感染宿主细胞、繁殖并在宿主血液中存活足够长的时间以保证其生存的能力通过吸血昆虫媒介传播。我们的目标是研究这些生存机制及其在克氏锥虫感染发病机制中的作用，并揭示控制克氏锥虫感染的潜在方法疾病。克氏锥虫在哺乳动物宿主血液和肠道中的存活该载体在很大程度上取决于它们在其使用过程中耐受渗透压剧烈变化的能力。通过哺乳动物宿主肾髓质的循环（1,300-1,400 mOsm/Kg）或其通道通过昆虫载体的直肠（1,000 mOsm/Kg），我们发现多磷酸盐（polyP）收缩液泡复合体（CVC）在它们的生存机制中起着至关重要的作用。最近的我们实验室的结果表明聚磷和/或焦磷酸盐 (PPi) 也可能参与克氏锥虫感染的发病机制。为了降低多聚磷水平，我们过度表达了一种降解酶水解 PPi 和 polyP，导致 PPi/polyP 急剧减少。突变型锥鞭毛体过度表达该酶并没有产生可检测到的寄生虫血症，并且在几个实验中所有受感染的动物在致命的感染中幸存下来。感染缺乏 PPi/polyP 的寄生虫的小鼠使用环磷酰胺进行免疫抑制后未能出现寄生虫血症，强烈表明感染已被彻底清除。我们的结果强调了 PPi/polyP 在克氏锥虫感染的发病机制。 PolyP 已被证明可作为细菌的毒力因子，但很少除了其促凝血和促炎活性之外，其在真核病原体中的作用也是众所周知的。在哺乳动物宿主内的生存还取决于克氏锥虫侵入不同宿主细胞的能力，从寄生泡液泡中逃逸并在细胞内复制。 T. cruzi 转唾液酸酶已被被证明在这些机制中具有重要作用。然而，评估的主要障碍是转唾液酸酶的功能是由于大量的寄生虫而从未获得敲除寄生虫基因拷贝分散在基因组中。我们发现转唾液酸酶通过收缩液泡在通往质膜的途中，并且通过干扰来破坏这种交通当它们通过 CVC 时，会导致寄生虫表面缺乏这些蛋白质。这对这种贩运机制以及干扰这种贩运的方法的研究将有助于了解克氏锥虫感染的发病机制。