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: 8946324
• 负责人: michael j lenardo
• 金额: $ 55.78万
• 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/8946324
• 关键词: Adaptor Signaling Protein; Adrenal Cortex Hormones; Affect; Age; Amino Acids; Apoptosis; Atypical lymphocyte; Autoimmune Process; Autoimmunity; B-Cell Lymphomas; Biological Markers; Blood; CASP10 gene; CASP8 Gene Mutation; CD8B1 gene; CD95 Antigens; Caspase; Cell Death; Cell Surface Receptors; Cells; Cellular Morphology; Cessation of life; Characteristics; Child; Childhood; Chromosomes; Chronic; Cleaved cell; Clinical; Clinical Protocols; Complement; Complex; Confidence Intervals; Cysteine-Rich Domain; DNA Sequence; Death Domain; Defect; Development; Diabetes Mellitus; Diagnosis; Disease; Elements; Enrollment; Equilibrium; Event; Exons; Failure; Family; Female; Functional disorder; Future; Gene Expression Microarray Analysis; Gene Mutation; Genes; Germ-Line Mutation; Hematopoietic Neoplasms; Hodgkin Disease; Homeostasis; Human; Hypersplenism; Immune; Immune system; Immunologic Deficiency Syndromes; In Vitro; Incidence; Individual; Inherited; KRAS2 gene; Laboratories; Lead; Ligand Binding; Ligands; Light; Lymphatic Diseases; Lymphocyte; Lymphoid; Lymphoma; Malignant Neoplasms; Mediating; Molecular; Molecular Abnormality; Morbidity - disease rate; Multiple Sclerosis; Mutation; Mycophenolate; N-ras Genes; Natural History; Necrosis; Non-Hodgkin' s Lymphoma; Non-Malignant; Organ; Outcome; Patients; Penetrance; Peripheral; Persons; Physiology; Process; Proteins; Protocols documentation; Publishing; Reaction; Recommendation; Relative (related person); Relative Risks; Reporting; Rheumatoid Arthritis; Risk; Role; Sepsis; Serum; Signal Transduction; Sirolimus; Somatic Mutation; Specimen; Splenectomy; Splenomegaly; Surgical complication; Swelling; Symptoms; Syndrome; T-Lymphocyte; TNFRSF6 gene; Techniques; Tissues; Transmembrane Domain; Tumor Necrosis Factor-alpha; United States National Institutes of Health; Vitamin B 12; Withdrawal; apoptosis in lymphocytes; autoimmune lymphoproliferative syndrome; base; caspase-10; caspase-8; clinical phenotype; cohort; comparative genomic hybridization; cytokine; cytopenia; extracellular; follow-up; immunoregulation; improved; insight; lymph nodes; male; mortality; mutant; next generation; programs; protein complex; 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. The FAS receptor is homotrimeric and activated by the cognate FAS ligand (FASL), another homotrimeric protein complex homologous to tumor necrosis factor (TNF). Following stimulation, the intracellular death domain (DD) portion of FAS nucleates an extended helical complex of the FADD adaptor protein and caspases-8 and -10. These caspases undergo proteolytic autoprocessing and cleave, in a signaling cascade, downstream effector caspases and other targets leading to the cellular death process of apoptosis. The FAS gene contains 9 exons spanning 26 Kb on chromosome 10q24.118. The first 5 exons encode the extracellular portion containing three cysteine-rich domains that control receptor trimerization and FASL binding. Exon 6 represents the transmembrane domain (TM), and the intracellular portion is encoded by exons 7 through 9. The FAS DD encoded by exon 9 is 85-amino acids long and critical for apoptosis signaling. ALPS-FAS is most frequently caused by heterozygous mutations that generate mutant FAS proteins, often with defective DDs. The defective FAS chains associate with wild-type chains via the pre-ligand assembly domain (PLAD) resulting in functionally defective receptor trimers, a phenomenon termed dominant interference. Less frequently, heterozygous mutations cause decreased FAS protein and haploinsufficiency. Mutations in genes encoding FASL, FADD, and CASP10, also cause ALPS termed ALPS-FASL, ALPS-FADD, and ALPS-CASP10,respectively. Germline mutations in CASP8 or somatic mutations in NRAS and KRAS cause ALPS-related syndromes with distinct clinical phenotypes. Importantly, FAS mutations are associated with in vitro lymphocyte apoptosis defects but may show variable clinical penetrance which has not been fully defined. in a study completed this year, we determined the full clinical, molecular and laboratory assessments of 150 ALPS-FAS patients and 63 healthy mutations positive relatives (HMPRs) to broaden the current understanding of the diagnosis and management of ALPS-FAS. We have found that ALPS presents in childhood with nonmalignant lymphadenopathy and splenomegaly associated with a characteristic expansion of mature CD4 and CD8 negative or double negative TCRalpha/beta+ T cells. Patients often present with chronic multilineage cytopenias due to autoimmune peripheral destruction and/or splenic sequestration of blood elements and have an increased risk of B cell lymphoma. Deleterious heterozygous mutations in the FAS gene are the most common cause of this condition, termed ALPS-FAS. We have determined the natural history and pathophysiology of 150 ALPS-FAS patients and 63 healthy mutation-positive relatives evaluated at the NIH clinical center over the last two decades. Our principal findings are that FAS mutations have a clinical penetrance of less than 60%, elevated serum vitamin B12 is a reliable and accurate biomarker of ALPS-FAS, and the major causes of morbidity and mortality in these patients are the complications of surgical splenectomy and the development of lymphoma. The fact that 41% (27/66) of the splenectomized patients in our cohort had at least one episode of post splenectomy sepsis and 6 of them have died profoundly reinforces the recommendation of avoiding splenectomy and managing chronic cytopenias pharmaceutically. With the long follow up of our study, we observed a significantly greater relative risk of lymphoma than previously reported. We uncovered 18 B cell lymphomas in ALPS-FAS individuals and HMPRs and one non-lymphoid hematopoietic malignancy. The age at diagnosis ranged from 5-60 years (median 17 years). The male to female ratio was 14:5. This included 10 cases of Hodgkins lymphoma in 150 ALPS-FAS patients compared to 0.067 expected giving an observed to expected ratio (O/E) of 149 (95%, confidence interval (CI) = 71 274) and 6 cases of Non-Hodgkin lymphoma compared to 0.099 expected (O/E = 61; 95% CI = 22 132) in ALPS-FAS. The O/E ratios were both highly significant. Standardized incidence ratio (SIR) values are 149 and 61 for Hodgkin and Non-Hodgkin lymphoma, respectively, in the current report versus 51 and 14, respectively, in a previous report we published in 2001. This difference may be related to the cumulative increase of lymphoma with age and accrual of additional events and person-years. Surveillance for lymphoma and avoiding splenectomy while controlling hypersplenism using corticosteroid-sparing treatments such as mycophenolate or sirolimus improves the outcome in ALPS-FAS patients. 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.

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。 FAS受体是同型二聚体的，并被同源性蛋白质复合物（FASL）激活，这是另一种同型蛋白质复合物（TNF）。刺激后，FAS的细胞内死亡结构域（DD）部分对FADD适配器蛋白和caspases -8和-10的延伸螺旋形成构成。这些胱天蛋白酶在信号级联，下游效应子胱天蛋白酶和其他靶标导致细胞凋亡过程中经历蛋白水解的自身处理和裂解。 FAS基因在10q24.118染色体上包含9个跨越26 kb的外显子。前5个外显子编码包含三个控制受体修剪和FASL结合的三个富含半胱氨酸的结构域的细胞外部分。外显子6代表跨膜结构域（TM），细胞内部分由外显子7至9编码。外显子9编码的FAS DD长85-氨基酸长，对于凋亡信号传导至关重要。 Alps-FAS最常是由杂合突变引起的，这些突变通常会产生突变的FAS蛋白，通常为DDS。有缺陷的FAS链通过配体组装域（PLAD）与野生型链相关，从而导致功能有缺陷的受体三聚体，这一现象称为显性干扰。杂合突变较少，导致FAS蛋白质和单倍弥补降低。编码FASL，FADD和CASP10的基因中的突变也分别导致Alps称为Alps-Fasl，Alps-Fadd和Alps-CASP10。 NRA和KRAS中CASP8或体细胞突变中的种系突变引起与阿尔卑斯山相关综合症具有不同的临床表型。重要的是，FAS突变与体外淋巴细胞凋亡缺陷有关，但可能显示出可变的临床渗透率，但尚未完全定义。在今年完成的一项研究中，我们确定了150名Alps-FAS患者和63个健康突变阳性亲属（HMPR）的全面临床，分子和实验室评估，以扩大对Alps-FAS诊断和管理的当前理解。 我们发现，阿尔卑斯山与成熟CD4和CD8阴性或双阴性tcralpha/beta+ T细胞的特征膨胀相关的非恶性淋巴结肿大和脾肿大。由于自身免疫外周的破坏和/或血液元素的脾隔离，患者经常出现慢性多核细胞质细胞减少症，并且患有B细胞淋巴瘤的风险增加。 FAS基因中有害的杂合突变是这种情况的最常见原因，称为Alps-Fas。在过去的二十年中，我们确定了150名Alps-FAS患者和63名健康突变阳性亲属的自然史和病理生理学，并在NIH临床中心进行了评估。我们的主要发现是，FAS突变的临床渗透率小于60％，血清维生素B12升高是ALPS-FAS的可靠且准确的生物标志物，这些患者的发病率和死亡率的主要原因是外科手术脾脏切除术的并发症。我们队列中有41％（27/66）的脾脏切除术患者至少有一集脾切除术败血症，其中6例死亡，这一事实严重增强了避免脾切除术和管理慢性细胞质的药物的建议。随着我们研究的长期跟进，我们观察到淋巴瘤的相对风险要比以前报道的要大得多。我们在阿尔卑斯山个体和HMPR和一个非淋巴造血恶性肿瘤中发现了18 B细胞淋巴瘤。 诊断年龄范围为5-60岁（中位17岁）。男性与女性比例为14：5。 其中包括150例ALPS-FAS患者的10例Hodgkins淋巴瘤，而预期为0.067，预期比率（O/E）为149例（95％，置信区间（CI）= 71 274）和6例非Hodgkin Lymphoma lymphoma lymphoma lymphomamoma lymphomamoma lymphoma homa，而预期为0.099（O/E/E = 61; 95％; 95％; 95％CI = 2222222222222222222222222222222222222222222222222325）。 O/E的比率都非常显着。霍奇金和非霍奇金淋巴瘤的标准化发病率比（SIR）值分别为149和61，在当前报告中分别与51和14分别为51和14，在我们在2001年发表的先前报告中。这种差异可能与淋巴瘤的累积增加有关，随着年龄和其他事件和人年的年龄和额外的事件和人数的增长。 淋巴瘤和避免脾切除术的监测，同时使用霉菌固醇治疗（如霉酚酸盐或西洛洛木素）控制超脾脏，可改善ALPS-FAS患者的结果。 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。