CHAGAS DISEASE: AUTOIMMUNITY STEMS FROM PARASITE INVASION OF HOST GENOME

恰加斯病：自身免疫源于寄生虫对宿主基因组的入侵

• 批准号: 7231625
• 负责人: ANTONIO RL TEIXEIRA
• 金额: $ 5.24万
• 依托单位: UNIVERSITY OF BRASILIA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-15 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7231625
• 关键词: CHAGAS; DISEASE; AUTOIMMUNITY; STEMS; PARASITE

DESCRIPTION (provided by the applicant): Chagas disease is the most lethal endemic disease in the Western Hemisphere. Various hypotheses have been proposed to explain the pathogenesis of Chagas disease, ranging from degradation of the affected tissues by the presence of the parasite to the possibility of an autoimmune response that is not dependent on the persistence of live infection. It has been shown that kDNA integration into the vertebrate host genome occurs frequently. Furthermore, the KDNA integration that takes place in early embryonic life perpetuates through the germline of vertebrarte hosts. We hypothesise that kDNA mutations in the course of Chagas disease can be associated with the histopathology evident in the vertebrate host heart tissue. In this study, the chicken model will be utilized because chicks hatched from Trypanosoma cruzi-inoculated eggs are infection-free, even though PCR amplification with specific nested primer sets and Southern blots reveal kDNA-positive bands and absence of nuclear DNA. In this kDNA-positive animal model we will determine the phenotypic modification of mutated host cells that could trigger autoimmunity in Chagas disease. Novel chimeric protein encoded by ORFs formed by kDNA and host DNA juxtaposition, which carries the potential to induce the immune response will be detected, and its a.a. sequence determined by mass spectrometry. The chimeric protein sequence will be correlated with a potential ORF detected by Blast analyses of DNA sequences originated from kDNA mutated birds. Moreover, the role of immune competent cells in the production of heart lesions present in kDNA mutated chickens will be determined in the congenic MHC(B), BB (B12/B12) and CC (C4/C4) lineages. This will consist of histo-compatible donor heart graft into the subcutaneous tissue at the base of the neck of kDNA mutated chickens showing ECG alterations typical of Chagas disease. Control experiments will consist of control histo-compatible chicken heart graft into kDNA-negative recipients of the same congenic strain. The heart graft will be excised from the recipient chicken at various set-times, and the tissue will be subjected to histopathological exam. The phenotypes of the immune cells associated with the rejection of the target heart will be detected. This investigation will set the basis for explaining long-lasting asymptomatic infections in individuals with harmless kDNA mutation, and Chagas heart disease in cases showing deleterious kDNA mutations in some chromosomal sites.

描述（由申请人提供）：恰加斯病是西半球最致命的地方病。人们提出了各种假设来解释恰加斯病的发病机制，从寄生虫的存在导致受影响的组织退化到不依赖于活体感染持续存在的自身免疫反应的可能性。研究表明，kDNA 整合到脊椎动物宿主基因组中的情况经常发生。此外，早期胚胎生命中发生的 KDNA 整合通过脊椎动物宿主的种系得以延续。我们假设恰加斯病过程中的 kDNA 突变可能与脊椎动物宿主心脏组织中明显的组织病理学相关。在这项研究中，将使用鸡模型，因为从接种克氏锥虫的蛋中孵出的小鸡是无感染的，尽管使用特定嵌套引物组的 PCR 扩增和 Southern 印迹显示 kDNA 阳性条带并且不存在核 DNA。在这个 kDNA 阳性动物模型中，我们将确定可能引发恰加斯病自身免疫的突变宿主细胞的表型修饰。由kDNA和宿主DNA并置形成的ORF编码的新型嵌合蛋白，其具有诱导免疫反应的潜力，将被检测到，其a.a.通过质谱法确定序列。嵌合蛋白序列将与通过对来自 kDNA 突变鸟类的 DNA 序列进行 Blast 分析检测到的潜在 ORF 相关联。此外，免疫活性细胞在 kDNA 突变鸡中存在的心脏病变产生中的作用将在同源 MHC(B)、BB (B12/B12) 和 CC (C4/C4) 谱系中确定。这将包括将组织相容的供体心脏移植到 kDNA 突变鸡颈部根部的皮下组织中，显示恰加斯病典型的心电图改变。对照实验将包括将对照组织相容性鸡心脏移植到同一同源品系的 kDNA 阴性受体中。将在不同的设定时间从受体鸡中切除心脏移植物，并对组织进行组织病理学检查。将检测与目标心脏排斥相关的免疫细胞的表型。这项研究将为解释具有无害 kDNA 突变的个体的长期无症状感染以及在某些染色体位点显示有害 kDNA 突变的病例中的恰加斯心脏病奠定基础。