Molecular Mechanisms Of The Autoimmune Lymphoproliferative Syndrome

自身免疫性淋巴增殖综合征的分子机制

• 批准号: 8336120
• 负责人: michael j lenardo
• 金额: $ 71.05万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8336120
• 关键词: Address; Affect; Alleles; Antigen Receptors; Apoptosis; Apoptotic; Atypical lymphocyte; Autoimmune Process; Autoimmunity; B-Lymphocytes; Binding; Birth; CD4 Positive T Lymphocytes; CD95 Antigens; Cell Death; Cell Surface Receptors; Cells; Cellular Morphology; Cessation of life; Child; Chronic; Clinical; Clinical Protocols; Complement; Coupling; DNA; DNA Sequence; Defect; Development; Diabetes Mellitus; Disease; Enrollment; Enzymes; Equilibrium; Exhibits; Exons; Failure; Family; Future; Gene Expression Microarray Analysis; Gene Mutation; Genes; Genetic; Germ-Line Mutation; HIV Infections; Homeostasis; Human; Immune; Immune System Diseases; Immune system; Immunologic Deficiency Syndromes; Inherited; Interleukin-2; Intracellular Second Messenger; Lead; Life; Ligands; Light; Link; Lymphocyte; Lymphocyte Activation; Lymphoid; Lymphopenia; Magnesium; Malignant Neoplasms; Mediating; Metabolic; Molecular; Molecular Abnormality; Multiple Sclerosis; Mutation; N-ras Genes; NF-kappa B; Necrosis; Organ; Pathway interactions; Patients; Peptide Hydrolases; Peripheral; Phospholipase C; Physiology; Play; Polyphosphates; Property; Proteins; Protocols documentation; RNA; Reaction; Receptor Activation; Receptor Signaling; Regulation; Regulator Genes; Rheumatoid Arthritis; Role; Second Messenger Systems; Signal Transduction; Specimen; Swelling; Symptoms; Syndrome; T-Lymphocyte; TNFRSF6 gene; Techniques; Thymus Gland; Tissues; United States National Institutes of Health; Virus Diseases; Withdrawal; Work; apoptosis in lymphocytes; autoimmune lymphoproliferative syndrome; base; caspase-10; caspase-8; cofactor; comparative genomic hybridization; cytokine; immunoregulation; insight; lymph nodes; magnesium ion; mutant; new therapeutic target; next generation; novel; programs; receptor; research study; response

This project is based on our discovery that genetic mutations in molecules that control the programmed death, or apoptosis, of lymphocytes are responsible for the Autoimmune Lymphoproliferative Syndrome (ALPS). ALPS is a disease affecting children that leads to loss of normal lymphocyte homeostasis leading to swollen lymph glands and organs. Because lymphocytes are the primary cell mediating immune reactions, this excess of lymphocytes leads to a pathological autoimmune attack on the patients own tissues. We have identified mutations in a death-inducing cell surface receptor termed Fas (also known as APO-1 or CD95) and in other molecules that regulate apoptosis. We have also identified a new disease entity called, Caspase-8 Deficiency State (CEDS) that is due to a genetic deficiency of caspase-8. This disease involves a loss of apoptotic control and lymphocyte expansion combined with a failure of normal lymphocyte activation through the antigen receptors. The consequence of this is a profound immunodeficiency state and a new insight that caspase-8, heretofore regarded solely as a cell death inducing protease, has a key role in antigen receptor signaling particularly for the induction of a gene regulatory factor called NF-kB. These studies promise to provide new insights into the molecular mechanisms that underlie autoimmune and immunodeficiency disease as well as revealing crucial steps in the pathway of programmed cell death in lymphocytes. In other related studies, we have shown that mutations in Fas and caspase-10 can be co-inherited in ALPS patients. We have also found that mutations in Fas ligand that cause ALPS have dominant-interfering properties thus explaining why such mutant alleles are disease-causing in a heterozygous state. Our work also permits us to address the pathogenic role of apoptosis defects in other immunological diseases such as X-linked proliferative disease or other less well-defined conditions. We are presently studying a class of these patients called ALPS Type III which do not display mutations in the Fas receptor, its ligand (Fas ligand), or caspase-10. We are using a variety of molecular analyses to determine the gene mutation that underlies disease in ALPS Type III. These experiments have been successful in uncovering the molecular basis of a new class of this disease, ALPS type IV. Patients with this disorder have typical clinical features of autoimmunity and abnormal lymphocyte homeostasis that are detected in ALPS, type I and II. however, these patients differ in that they have a strikingly decreased death in response to cytokine withdrawal rather than a defect in death receptor apoptosis. The molecular basis of this disorder is a reduction in the apoptosis protein Bim due to an inherited germline mutation in the N-Ras oncogene. We plan to continue to examine unusual Alps Type III cases to understand their molecular basis. Our guiding principle is that patient specimens from poorly understood diseases can yield valuable insights into disease mechanisms and normal physiology if investigated properly at the molecular level. We have found several new mutations in these unusual patient disorders and are currently characterizing their role in lymphocyte homeostasis and apoptosis. In studying a group of patients with abnormal immune regulation, we focused in the past year on a group of patients that had idiopathic CD4 lymphopenia. These patients had exhibited this condition from birth and had no known external causes of low CD4 T cells such as HIV infection. Our studies led to the the identification of a magnesium channel, termed MagT1, that is critical for the selection of CD4 T cells in the thymus as well as peripheral function of T but not B lymphocytes. The magnesium ion, Mg(2+), is essential for all life as a cofactor for ATP, polyphosphates such as DNA and RNA, chorophyll, and metabolic enzymes, but whether it plays a part in intracellular signalling (as Ca(2+) has been shown to play) was unexplored. we discovered inactivating mutations in the magnesium transporter gene, MAGT1, in a novel X-linked human immunodeficiency characterized by CD4 lymphopenia, severe chronic viral infections, and defective T-lymphocyte activation in the patients we were investigating. We found that a rapid transient Mg(2+) influx is induced by antigen receptor stimulation in normal T cells and by growth factor stimulation in non-lymphoid cells and that this influx is critical for cellular activation. MAGT1 defects abrogate this Mg(2+) influx and decrease the basal level of free Mg(2+) but not the total bound Mg(2+). These alterations lead to impaired responses to antigen receptor engagement, including defective activation of phospholipase Cγ1 and a markedly impaired Ca(2+) influx in T cells but not B cells. Our observations reveal a likely role for Mg(2+) as an intracellular second messenger coupling cell-surface receptor activation to intracellular effectors and identify MAGT1 as a possible target for novel therapeutics.

该项目是基于我们发现的，即控制淋巴细胞的编程死亡或凋亡的分子中的基因突变负责自身免疫性淋巴增生综合征（ALPS）。阿尔卑斯山是一种影响儿童的疾病，导致正常淋巴细胞稳态失去导致淋巴腺和器官肿胀。由于淋巴细胞是介导免疫反应的主要细胞，因此过量的淋巴细胞会导致对患者自己组织的病理自身免疫性攻击。我们已经在称为FA的死亡的细胞表面受体（也称为APO-1或CD95）以及调节细胞凋亡的其他分子中确定了突变。我们还确定了一个新的疾病实体，称为CASPASE-8缺乏状态（CEDS），该状态是由于caspase-8的遗传缺乏造成的。 该疾病涉及凋亡控制和淋巴细胞膨胀的丧失，以及通过抗原受体的正常淋巴细胞激活的失败。 结果的结果是一种深远的免疫缺陷状态和一种新的见解，即Caspase-8（迄今为止仅视为诱导细胞死亡蛋白酶）在抗原受体信号传导中具有关键作用，特别是对于诱导了称为NF-KB的基因调节因素。 这些研究有望提供有关自身免疫性和免疫缺陷疾病基础的分子机制的新见解，并在淋巴细胞中编程细胞死亡的途径中揭示了关键步骤。 在其他相关研究中，我们已经表明，ALPS患者可以共同介绍FAS和CASPASE-10中的突变。 我们还发现，导致阿尔卑斯山的FAS配体中的突变具有显着性干扰性质，从而解释了为什么这种突变等位基因在杂合状态下引起疾病的原因。 我们的工作还允许我们解决凋亡缺陷在其他免疫疾病中的致病作用，例如X连锁的增殖疾病或其他定义不太明确的疾病。 我们目前正在研究一类称为Alps III的患者，该患者在FAS受体，配体（FAS配体）或CASPASE-10中不显示突变。 我们正在使用各种分子分析来确定阿尔卑斯山III型疾病构成的基因突变。这些实验已成功地揭示了该疾病的新类别ALPS IV的分子基础。 患有这种疾病的患者具有自身免疫性和异常淋巴细胞稳态的典型临床特征，在ALPS，I型和II型中检测到。但是，这些患者的不同之处在于，由于细胞因子戒断而不是死亡受体凋亡的缺陷，他们的死亡显着降低。该疾病的分子基础是由于N-RAS癌基因的遗传生殖线突变，凋亡蛋白BIM的降低。我们计划继续检查异常的III型病例，以了解其分子基础。 我们的指导原则是，如果在分子水平上对疾病机制和正常生理学的疾病，患者的标本中的疾病较低的疾病标本可以产生有价值的见解。 我们在这些异常的患者疾病中发现了一些新的突变，目前正在表征它们在淋巴细胞稳态和凋亡中的作用。 在研究一组异常免疫调节的患者时，我们将重点放在一组患有特发性CD4淋巴细胞减少症的患者上。 这些患者从出生开始就表现出这种疾病，并且没有发现低CD4 T细胞（例如HIV感染）的外部原因。 我们的研究导致了称为MAGT1的镁通道的鉴定，这对于胸腺中CD4 T细胞的选择至关重要，而T淋巴细胞的含量和外周功能至关重要。 镁离子Mg（2+）对于ATP，DNA和RNA，Chorophyll和代谢酶等辅助因子的所有生命都是必不可少的，但是未探索它是否在细胞内信号传导（Ca（2+）中扮演）。我们在镁转运蛋白基因MAGT1中发现了一种新型的X连锁的人免疫缺陷，其特征是以CD4淋巴细胞减少症，严重的慢性病毒感染和有缺陷的T-淋巴细胞激活在我们正在研究的患者中。我们发现，正常T细胞中的抗原受体刺激和非淋巴样细胞中的生长因子刺激诱导了快速的瞬态MG（2+）流入，并且这种流入对于细胞激活至关重要。 MAGT1缺陷消除了此Mg（2+）涌入，并降低自由Mg（2+）的基础水平，但不能降低总结合Mg（2+）。 这些改变会导致对抗原受体参与的反应受损，包括磷脂酶Cγ1的有缺陷激活和T细胞中明显受损的Ca（2+）涌入，而不是B细胞。我们的观察结果揭示了Mg（2+）作为细胞内的第二信使耦合细胞表面受体激活对细胞内效应子的作用，并将MAGT1鉴定为新型治疗剂的可能靶标。