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 浸润、活化、寡克隆和无反应性T淋巴细胞。大多数OS患者缺乏循环B 淋巴细胞，并显示严重的低丙种球蛋白血症，但正常或血清IgE升高。我们有 发现大多数OS患者携带RAG基因的亚型突变， 消除V（D）J重组。然而，参与V（D）J重组的基因中的亚晶突变， 也可引起渗漏性SCID，伴随活化和无反应性T细胞的积聚，而无组织损伤。 我们已经发现转录因子Aire和组织特异性转录本在细胞中表达很低， 胸腺的OS患者，提高了自身反应性T细胞的阴性选择可能不是 适当的地方。此外，OS中调节性T细胞（TCRs）的发育可能会改变，因为 这些患者的胸腺缺乏参与胸腺发育的哈萨尔小体。最后， 环境因素也可能参与OS的病理生理学，因为已经表明， 具有亚型RAG突变的婴儿的疾病表型可以通过暴露于 病原体我们将利用最近开发的三种亚型rag2，rag1， 和Iig 4突变，以研究OS和渗漏SCID的细胞和分子机制。 我们的总体假设是，可变的临床和免疫学表型相关的 参与V（D）J重组的基因中的亚型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， 所产生的表型可被环境因素改变。 为了验证这一假设，我们将评估突变体的V（D）J重组活性。我们将分析 在这些模型中的负选择，并使用过继转移来评估受损的功能的作用， 你好最后，我们将用TLR激动剂、MCMV和恶唑酮激发小鼠，使其沉淀或 加速疾病的表型。 我们希望这些独特的动物模型的详细特征将提供关键信息， 了解OS和渗漏性SCID的病理生理学，以及其他更常见的疾病， 免疫调节将收集的信息也可能有助于开发新的和 这些免疫缺陷和反应不良的严重病症的更适当的治疗形式。

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.