Molecular Mechanisms Of The Autoimmune Lymphoproliferative Syndrome And Other Immunoregulatory Disorders

这个项目最初是基于我们的发现，即影响淋巴细胞程序性死亡或凋亡的基因突变是自身免疫淋巴增殖综合征(Alps)的原因。阿尔卑斯病是一种先天性疾病，导致正常淋巴细胞稳态丧失，表现为淋巴腺和器官肿大。淋巴细胞过多会导致患者自身组织的病理性自身免疫攻击。在阿尔卑斯综合征的临床研究中，许多患者被推荐到我们的计划中进行评估，这些患者患有其他免疫调节和免疫缺陷综合征。因此，我们启动了临床基因组学计划，以确定这些疾病的遗传原因。除了国立卫生研究院的患者外，我们还在中国、土耳其和印度建立了临床研究中心，为许多患者提供细胞和基因组水平的研究。 我们最近发现了一种非常有趣的遗传病，影响了10名患者，其中大部分来自我们位于土耳其伊斯坦布尔的中心，他们遭受着腹痛和腹泻的痛苦，这些疾病是由早发性蛋白失失性肠病(PLE)伴淋巴管扩张、低蛋白血症引起的浮肿、吸收不良以及较少见的肠炎、反复感染和血管病理性血栓栓塞病引起的。有趣的是，这种疾病即使不完全相同，也与1961年由美国国立卫生研究院临床中心的托马斯·A·沃尔德曼博士首次报道的瓦尔德曼病非常相似。我们发现常染色体隐性突变导致编码CD55/衰变加速因子基因的蛋白表达缺失。患者T淋巴细胞和CD55缺陷细胞系表现出补体因子C3d异常增多。CD55基因重组阻止了C3d沉积。刺激患者T淋巴细胞上的过敏性毒素受体会产生肿瘤坏死因子α，从而导致抗凝蛋白血栓调节蛋白与促凝血蛋白组织因子的比率降低。CD97对CD55的共刺激作用和IL-10的偶发产生在患者T淋巴细胞中存在缺陷。因此，CD55缺乏症伴补体过度激活、血管病理性血栓形成和PLE(Chaple)病是由于CD55基因的常染色体隐性功能丧失(LOF)突变引起的补体激活异常所致。有趣的是，沃尔德曼博士最初将蛋白缺失性肠病归因于原发性肠道淋巴管扩张，大约50年后，我们的发现为这种疾病提供了基因病因。此外，我们的体外结果表明，FDA批准的补体抑制治疗药物eculizumab(Soliris，Alexion)可能对这些患者有利。我们现在已经在伊斯坦布尔马尔马拉医院接受治疗的30多名患者中测试了这一假设，在这些患者中，eculizumab取得了显著的治疗效果。我们发现，几乎在给药后立即，腹泻和腹痛就会停止。在为期4周的2次治疗后，血液蛋白水平和其他异常情况得到逆转。因此，我们的结果表明，这种特殊的先天性免疫臂的紊乱可能会导致严重的疾病。此外，这些结果是一个重要的证明，表明基于基因洞察的精确医学如何对一种发病率和死亡率高的严重疾病产生巨大影响。

This project was originally based on our discovery that genetic mutations that affect programmed death, or apoptosis, of lymphocytes are responsible for the Autoimmune Lymphoproliferative Syndrome (ALPS). ALPS is a congenital disease causing loss of normal lymphocyte homeostasis manifested as swollen lymph glands and organs. This excess of lymphocytes leads to a pathological autoimmune attack on the patients own tissues. During the clinical investigations on ALPS, many patients have been referred to our program with other immunoregulatory and immunodeficiency syndromes for evaluation. Therefore we launched a clinical genomics program to identify the genetic causes of these diseases. In addition to NIH patients, we have also established clinical research centers in China, Turkey, and India, providing many patients to study at the cellular and genomic level. We recently discovered a very interesting genetic disease affecting 10 patients, mostly coming from our center in Istanbul, Turkey, suffering from abdominal pain and diarrhea caused by early-onset protein-losing enteropathy (PLE) with lymphangiectasia, edema due to hypoproteinemia, malabsorption, and, less frequently, bowel inflammation, recurrent infections, and angiopathic thromboembolic disease. Interestingly, this disease was very similar if not identical to a condition called Waldmann's disease, that was first reported in 1961 by Dr. Thomas A. Waldmann at the NIH clinical center. We identified autosomal recessive mutations leading to loss of protein expression in the gene encoding CD55/Decay accelerating factor. Patient T lymphocytes and CD55-deficient cell lines displayed abnormally increased deposition of complement factor C3d. Genetic reconstitution of CD55 prevented C3d deposition. Stimulation of anaphylatoxin receptors on patient T lymphocytes produced increased tumor necrosis factor alpha, which caused a decreased ratio of the anti-coagulatory protein thrombomodulin to the pro-coagulatory protein tissue factor. CD55 costimulation by CD97, and the contingent production of interleukin-10, was defective in patient T lymphocytes. Hence, CD55 deficiency with hyperactivation of complement, angiopathic thrombosis, and PLE (CHAPLE) disease is caused by abnormal complement activation due to autosomal recessive loss-of-function (LOF) mutations in the CD55 gene. Interestingly, Dr. Waldmann had originally attributed protein-losing enteropathy to primary intestinal lymphangiectasis and, some 50 years later, our findings provide a genetic etiology for this disease. Moreover, our in vitro results suggest that eculizumab (Soliris, Alexion), an FDA-approved, complement-inhibiting therapeutic may benefit these patients. We have now tested that hypothesis in over 30 patients that have been treated at Marmara hospital in Istanbul in which eculizumab has achieved dramatic treatment effects. We find that almost immediately after administration of the drug, the diarrhea and abdominal pain ceases. After 2 treatments over the course of 4 weeks, blood protein levels and other abnormalities were reversed. Thus, our results show how disorders of this specialized arm of innate immunity can lead to severe disease. Moreover, these results are an important demonstration of how precision medicine based on genetic insights can have a dramatic impact on a severe disease with a high rate of morbidity and mortality.