Murine gene knock-in models fo Omenn Syndrome and leaky SCID

Omenn 综合征 (OS) 是一种联合免疫缺陷，其特征是由于以下因素导致的严重组织损伤： 浸润、活化、寡克隆和无能 T 淋巴细胞。大多数 OS 患者缺乏循环 B 淋巴细胞并表现出严重的低丙种球蛋白血症，但血清 IgE 正常或升高。我们有 发现大多数 OS 患者携带 RAG 基因的亚等位突变，这些突变减少但不增加 废除V(D)J重组。然而，参与 V(D)J 重组的基因的亚等位突变 也可能导致渗漏性 SCID，伴随着活化和无反应性 T 细胞的积累，但没有组织损伤。 我们发现转录因子 Aire 和组织特异性转录物在 OS 患者的胸腺，增加了自身反应性 T 细胞的阴性选择可能无法被抑制的可能性。 正确就位。此外，调节性 T 细胞 (Treg) 的发育可能会在 OS 中发生改变，因为 这些患者的胸腺缺乏参与 Tregs 发育的哈萨尔氏小体。最后， 环境因素也可能参与 OS 的病理生理学，因为已经表明， 具有低等态 RAG 突变的婴儿的疾病表型可以通过暴露于 病原体。我们将利用三个最近开发的亚效型 rag2、ragl、 和 Iig4 突变，以研究 OS 和渗漏 SCID 背后的细胞和分子机制。 我们的总体假设是，与以下因素相关的可变临床和免疫表型 参与V(D)J重组的基因的亚等位性突变反映了不同程度的损伤 V(D)J 重组影响中枢耐受的缺失和非缺失机制，并且 所产生的表型可能会被环境因素改变。 为了检验这个假设，我们将评估突变体的 V(D)J 重组活性。我们将分析 这些模型中的负选择，并使用过继转移来评估受损功能的作用 特雷格斯。最后，我们将用 TLR 激动剂、MCMV 和恶唑酮攻击小鼠，以沉淀或 加速疾病表型的发生。 我们期望这些独特动物模型的详细表征将为 了解 OS 和漏性 SCID 的病理生理学，以及其他更常见的疾病的病理生理学 免疫调节。将收集的信息也可能对开发新颖的和有用的 更合适的治疗方式来治疗这些严重的免疫缺陷和反应不良状况。

Omenn syndrome (OS) is a combined immunodeficiency characterized by severe tissue damage due to infiltrating, activated, oligoclonal and anergic T lymphocytes. Most patients with OS lack circulating B lymphocytes and show profound hypogammaglobulinemia, but normal or elevated serum IgE. We have found that most patients with OS carry hypomorphic mutations of the RAG genes that decrease but do not abolish V(D)J recombination. However, hypomorphic mutations in genes involved in V(D)J recombination may also cause leaky SCID, with accumulation of activated and anergic T cells, without tissue damage. We have found that the transcription factor Aire and tissue-specific transcripts are poorly expressed in the thymus of patients with OS, raising the possibility that negative selection of autoreactive T cells may not be properly in place. In addition, development of regulatory T cells (Tregs) is likely to be altered in OS, as the thymus of these patients lacks Hassall's corpuscles, which are involved in Tregs development. Finally, environmental factors may also be involved in the pathophysiology of OS, as it has been shown that the disease phenotype in infants with hypomorphic RAG mutations can be dramatically modified by exposure to pathogens. We will take advantage of three recently developed murine models of hypomorphic rag2, ragl, and Iig4 mutations to investigate the cellular and molecular mechanisms that underlie OS and leaky SCID. Our overall hypothesis is that the variable clinical and immunological phenotype associated with hypomorphic mutations in genes involved in V(D)J recombination reflects a different degree of impairment of V(D)J recombination that affects deletional and non deletional mechanisms of central tolerance, and that the resulting phenotype may be modified by environmental factors. To test this hypothesis,we will evaluate the V(D)J recombination activity of the mutants. We will analyze negative selection in these models, and use adoptive transfer to assess the role of impaired function of Tregs. Finally, we will challenge the mice with TLR agonists, MCMV and oxazolone to precipitate or accelerate the disease phenotype. We expect that detailed characterization of these unique animal models will provide critical information to understand the pathophysiology of OS and leaky SCID, but also of other, more common, disorders of immune regulation. The information that will be collected might be useful also for development of novel and more appropriate forms of treatment of these severe conditions of immune deficiency and dysreactivity.