Trypanosoma brucei-induced dyshematopoiesis: blocked B lymphopoiesis

布氏锥虫引起的造血障碍：B 淋巴细胞生成受阻

基本信息

批准号：
7386807
负责人：
SAMUEL J BLACK
金额：
$ 7.51万
依托单位：
UNIVERSITY OF MASSACHUSETTS AMHERST
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-06-01 至 2010-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7386807
关键词：
Address Affect Africa South of the Sahara African African Trypanosomiasis Agricultural Development Antibodies Antibody Formation Antigens Area B cell differentiation B-Cell Development B-Lymphocytes Berenil Blood Bone Marrow CD19 gene Cell Maturation Cell surface Cells Cellular Immunity Cessation of life Characteristics Coculture Techniques Competence DNA DNA Sequence Rearrangement Data Defect Development Differentiation Antigens Disease Domestic Animals Flow Cytometry Fluorescence-Activated Cell Sorting Future Gene Expression Gene Expression Profile Gene Expression Profiling Gene Rearrangement Genomics Giemsa stain Goals Green Fluorescent Proteins Host Defense Human Immune Immunodeficient Mouse Immunoglobulins In Vitro Individual Infection Infection Control Intercellular Fluid Intervention J segment gene Knowledge Laboratory Animals Lead Lymph Lymphoid Lymphopoiesis Maintenance Mastigophora Mature B-Lymphocyte Mediating Mental Depression Methodology Molecular Monitor Monoclonal Antibodies Mus Nature Organ PTPRC gene Parasitemia Parasites Pathology Pathway interactions Persons Plasma Polymerase Chain Reaction Population Protozoa RNA Receptors, Antigen, B-Cell Reverse Transcriptase Polymerase Chain Reaction Specific qualifier value Spleen Staging Stromal Cells Surface System T-Lymphocyte Testing Transcription factor genes Trypanocidal Agents Trypanosoma Trypanosoma brucei brucei Trypanosomiasis Work base disorder control exhaustion immune function improved in vivo mouse model nagana prevent progenitor response restoration size surface coating transcription factor

项目摘要

DESCRIPTION (provided by applicant): African trypanosomes are highly antigenically variable flagellated protozoa that cause fatal disease of people and domestic animals. About 300,000 persons have trypanosomiasis at present and the disease threatens an additional 60 million individuals in sub-Saharan Africa as well as severely limiting agricultural development in an area the size of USA. African trypanosomes replicate by binary fission in the blood and interstitial fluids and are controlled by host antibody responses against their variable coat antigens. Infected hosts lose the ability to mount an effective antibody response as the disease progresses resulting in poor control of newly arising trypanosome antigenic types, sustained pathology and eventually death. Our long term goal is to understand how T. brucei affects the B cell (antibody forming cell) system and to use this knowledge to develop strategic interventions that will preserve immune function and disease control. Our on- going analyses in the mouse model show that there is a rapid expansion of early B cell progenitors in the bone marrow and spleen, but the loss of newly formed and mature B cells from these organs, features of dyshematopoiesis that are reversed by clearance of trypanosomes from infected mice by treatment with the trypanocidal drug Berenil. These observations lead us to hypothesize that T. brucei induces a reversible block in B lymphopoiesis that prevents replenishment of the pools of new and mature B cell, which leads to B- cell clonal exhaustion and the collapse of B cell-mediated immunity. We will address this hypothesis in the following specific aims: i) identify the stage at which B lineage development is arrested in Trypanosoma brucei-infected mice ii) determine whether the block in B cell development results from truncated or aberrant B cell differentiation, iii) determine whether blocked B cells resume development when placed in trypanosome- free hosts, or grown in vitro, and if so, whether T. brucei or components of T. brucei prevent escape from the block in development. Methodologies will include: (i) cell surface differentiation antigen profiling using monoclonal antibodies specific for B cell developmental stages, (ii) transcription factor and immunoglobulin gene expression profiling of discrete B cell developmental stages isolated by fluorescence activate cell sorting (FACS) from the spleen and bone marrow of normal and trypanosome-infected mice, (iii) developmental analyses of B cell progenitors FACS isolated as in aim ii, and grown in immunodeficient mice (RAG-/-) and in vitro in the presence and absence of trypanosomes and extracts. Public heath relevance includes the elucidation of the cellular basis for trypanosome-induced B cell exhaustion and the loss of host ability to make protective antibodies responses. Narrative: Loss of the ability to make protective antibody responses and consequently to control parasitemia is a common feature of African trypanosomiasis in people, domestic and laboratory animals. Using the mouse model we have shown an infection-induced reversible block in B lymphocyte development that prevents the maintenance of pools of newly formed and mature B cell leading to B cell clonal exhaustion and thus, collapse of humoral immune competence. We propose to identify the affected B cell developmental stage and the nature of the developmental block as a step towards elucidating the molecular basis of this newly identified mechanism of disease-associated immuno-depression.

描述（由申请人提供）：非洲锥虫是一种抗原性高度可变的有鞭毛原生动物，可导致人类和家畜致命疾病。目前约有 30 万人患有锥虫病，该疾病威胁着撒哈拉以南非洲地区另外 6000 万人，并严重限制了美国面积的农业发展。非洲锥虫通过血液和间质液中的二元裂变进行复制，并受到针对其可变外壳抗原的宿主抗体反应的控制。随着疾病的进展，受感染的宿主失去产生有效抗体反应的能力，导致对新出现的锥虫抗原类型控制不佳、持续病理并最终死亡。我们的长期目标是了解布氏锥虫如何影响 B 细胞（抗体形成细胞）系统，并利用这些知识制定战略干预措施，以保持免疫功能和疾病控制。我们在小鼠模型中正在进行的分析表明，骨髓和脾脏中早期 B 细胞祖细胞快速扩增，但这些器官中新形成和成熟的 B 细胞丢失，造血障碍的特征可通过清除逆转通过用杀锥虫药物 Berenil 治疗，从受感染的小鼠中提取锥虫。这些观察结果使我们推测布氏锥虫会诱导 B 淋巴细胞生成的可逆性阻断，从而阻止新的和成熟的 B 细胞库的补充，从而导致 B 细胞克隆耗竭和 B 细胞介导的免疫崩溃。我们将在以下具体目标中解决这一假设：i) 确定布氏锥虫感染小鼠中 B 谱系发育受阻的阶段 ii) 确定 B 细胞发育受阻是否是由截短或异常的 B 细胞分化引起的，iii)确定被阻断的 B 细胞在置于不含锥虫的宿主中或在体外生长时是否会恢复发育，如果是这样，布氏锥虫或布氏锥虫的成分是否会阻止发育中的阻断逃逸。方法包括：(i) 使用 B 细胞发育阶段特异性单克隆抗体进行细胞表面分化抗原分析，(ii) 通过荧光激活细胞分选 (FACS) 从脾脏分离的离散 B 细胞发育阶段的转录因子和免疫球蛋白基因表达分析以及正常和锥虫感染小鼠的骨髓，(iii) B 细胞祖细胞的发育分析 FACS 按照目的 ii 分离并在免疫缺陷小鼠中生长(RAG-/-) 以及在存在和不存在锥虫和提取物的情况下的体外实验。公共卫生相关性包括阐明锥虫诱导的 B 细胞耗竭和宿主产生保护性抗体反应的能力丧失的细胞基础。叙述：丧失产生保护性抗体反应并进而控制寄生虫血症的能力是非洲锥虫病在人类、家畜和实验动物中的一个共同特征。使用小鼠模型，我们发现感染诱导的 B 淋巴细胞发育可逆性受阻，阻止新形成和成熟 B 细胞池的维持，导致 B 细胞克隆耗竭，从而导致体液免疫能力崩溃。我们建议确定受影响的 B 细胞发育阶段和发育障碍的性质，作为阐明这种新发现的疾病相关免疫抑制机制的分子基础的一步。