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: 8555824
• 负责人: michael j lenardo
• 金额: $ 87.47万
• 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/8555824
• 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; Physiology; Play; Polyphosphates; Property; Proteins; Protocols documentation; RNA; Reaction; Receptor Activation; Receptor Signaling; 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 2012, we have focused 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 partin 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 Cgamma1 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.

该项目基于我们的发现，即控制淋巴细胞程序性死亡或凋亡的分子中的基因突变是导致自身免疫性淋巴细胞增殖综合征（ALPS）的原因。ALPS是一种影响儿童的疾病，导致正常淋巴细胞稳态的丧失，从而导致淋巴腺和器官肿胀。因为淋巴细胞是介导免疫反应的主要细胞，所以这种过量的淋巴细胞导致对患者自身组织的病理性自身免疫攻击。我们已经确定了一种称为Fas（也称为APO-1或CD 95）的死亡诱导细胞表面受体和其他调节细胞凋亡的分子的突变。我们还发现了一种新的疾病实体，称为Caspase-8缺陷状态（CEDS），这是由于Caspase-8的遗传缺陷。 这种疾病涉及凋亡控制和淋巴细胞扩增的丧失，以及通过抗原受体的正常淋巴细胞活化的失败。 其结果是一种严重的免疫缺陷状态和一种新的见解，即迄今为止仅被认为是细胞死亡诱导蛋白酶的胱天蛋白酶-8在抗原受体信号传导中具有关键作用，特别是用于诱导称为NF-κ B的基因调节因子。 这些研究有望为自身免疫和免疫缺陷疾病的分子机制提供新的见解，并揭示淋巴细胞程序性细胞死亡途径中的关键步骤。 在其他相关研究中，我们已经表明，Fas和caspase-10的突变可以在ALPS患者中共同遗传。 我们还发现导致ALPS的Fas配体突变具有显性干扰特性，从而解释了为什么这种突变等位基因在杂合状态下是致病的。 我们的工作也使我们能够解决凋亡缺陷在其他免疫性疾病，如X-连锁增殖性疾病或其他不太明确的条件下的致病作用。 我们目前正在研究一类称为ALPS III型的患者，这些患者不显示Fas受体，其配体（Fas配体）或caspase-10的突变。 我们正在使用各种分子分析来确定导致ALPS III型疾病的基因突变。这些实验已经成功地揭示了这种疾病的一个新类别，ALPS IV型的分子基础。 患有这种疾病的患者具有在ALPS I型和II型中检测到的自身免疫和异常淋巴细胞稳态的典型临床特征。然而，这些患者的不同之处在于，他们响应于细胞因子撤除而具有显著降低的死亡，而不是死亡受体凋亡缺陷。这种疾病的分子基础是由于N-Ras癌基因的遗传性种系突变导致凋亡蛋白Bim减少。我们计划继续研究不寻常的阿尔卑斯山III型病例，以了解其分子基础。 我们的指导原则是，如果在分子水平上进行适当的研究，来自不太了解的疾病的患者标本可以对疾病机制和正常生理产生有价值的见解。 我们在这些不寻常的患者疾病中发现了几个新的突变，目前正在表征它们在淋巴细胞稳态和凋亡中的作用。 2012年，我们重点关注了一组患有特发性CD 4淋巴细胞减少症的患者。 这些患者从出生起就表现出这种情况，并且没有已知的CD 4 T细胞低水平的外部原因，例如艾滋病毒感染。 我们的研究导致了镁通道的鉴定，称为MagT 1，其对于胸腺中的CD 4 T细胞的选择以及T淋巴细胞而不是B淋巴细胞的外周功能是至关重要的。 镁离子，Mg（2+），作为ATP、多磷酸盐（如DNA和RNA）、叶绿素和代谢酶的辅助因子，对所有生命都是必不可少的，但它是否在细胞内信号传导中起作用（如Ca（2+）已被证明起作用）尚未探索。我们在一种新的X连锁人类免疫缺陷中发现了镁转运蛋白基因MAGT 1的失活突变，其特征是我们所研究的患者中的CD 4淋巴细胞减少症、严重的慢性病毒感染和T淋巴细胞活化缺陷。我们发现，一个快速的瞬时Mg（2+）流入诱导抗原受体刺激在正常的T细胞和生长因子刺激在非淋巴细胞，这种流入是至关重要的细胞活化。MAGT 1缺陷消除了这种Mg（2+）流入，并降低了游离Mg（2+）的基础水平，但不降低总结合Mg（2+）。 这些改变导致对抗原受体结合的反应受损，包括磷脂酶C γ 1的活化缺陷和T细胞中而非B细胞中的Ca（2+）内流显著受损。我们的观察揭示了Mg（2+）作为细胞内第二信使将细胞表面受体活化偶联到细胞内效应物的可能作用，并将MAGT 1鉴定为新疗法的可能靶点。