Attenuation of Lupus by Foxo3

 描述(申请人提供)：自身免疫性疾病系统性红斑狼疮(SLE)的特点是对核抗原的耐受性丧失，并产生自身抗体。这些形成免疫复合体，促进炎症和组织损伤。一些证据表明，SLE的发病机制是通过丧失获得性免疫耐受性和天然免疫系统的过度活跃来调节的。后者与促炎细胞因子的产生增加有关，包括I型IFN。明确控制这些事件的分子机制可能会揭示SLE的新治疗靶点。我们假设转录因子Foxo3有助于减轻狼疮的严重程度。FOX03是FOXO转录因子家族中的一员，该家族在转录水平和翻译后水平均受PI3激酶信号的下调。我们的初步数据表明，Foxo3缺陷小鼠改变了未成熟B细胞的凋亡和受体编辑，这两种方式都是中枢B细胞耐受的手段。FOXO_3在髓系细胞中也有几种独特的抗炎作用。它抑制树突状细胞的致炎反应，并已知限制I型IFN和干扰素签名基因在人和小鼠巨噬细胞中的表达。Foxo3mRNA表达升高与克罗恩病和类风湿性关节炎的严重程度降低有关，肿瘤浸润性树突状细胞由于Foxo3mRNA表达增加而具有耐受性。这突显了Foxo3及其mRNA表达在调节炎症反应中的重要性。有趣的是，初步分析表明，SLE患者在Foxo3和一系列相关基因的mRNA表达方面分为两个不同的组(我们将其称为“Foxo3特征”)。在这里，我们将通过以下目的来检验Foxo3在狼疮中发挥保护作用的假设。在目标1中，我们将询问在广泛的bcr编辑后保持自身反应的B细胞是否在没有Foxo3的情况下存活而不是被删除。我们将研究Foxo3-/-小鼠的编辑和缺失，使用RS重组的聚合酶链式反应分析，一种受体编辑的衡量标准，以及一种删除自身反应性B细胞的Ig TG模型。在目标2中，我们将确定在没有Foxo3的情况下，容易发生狼疮的小鼠是否会患上更严重的疾病，如果是这样的话，哪些细胞类型介导了这种影响。在目标3中，我们将比较表达低水平Foxo3和高水平Foxo3的SLE患者的基因表达谱和临床疾病参数，以确定高水平Foxo3和相关“签名”基因的患者是否有改变的病程。这项工作将确定Foxo3是否限制狼疮的严重程度，并为SLE患者亚组确定一组独特的Foxo3相关生物标记物。这些研究还将为针对Foxo3或Foxo3签名基因的新治疗方法铺平道路。

 DESCRIPTION (provided by applicant): The autoimmune disease Systemic Lupus Erythematosus (SLE) is characterized by a loss of tolerance to nu- clear antigens and the production of autoantibodies. These form immune complexes which promote inflammation and tissue damage. Several lines of evidence suggest that SLE pathogenesis is mediated by loss of adaptive immune tolerance coupled with hyperactivity of the innate immune system. The latter is associated with increased production of pro-inflammatory cytokines, including type I IFNs. Defining the molecular mechanisms that control these events may reveal novel therapeutic targets for SLE. We hypothesize that the transcription factor Foxo3 serves to attenuate the severity of lupus. Foxo3 is a member of the Foxo family of transcription factors which are downregulated by PI3 kinase signaling at both the mRNA and posttranslational levels. Our preliminary data indicate that Foxo3-deficient mice have altered immature B cell apoptosis and receptor editing, both means of central B cell tolerance. Foxo3 also has several unique anti-inflammatory roles in myeloid lineage cells. It dampens proinflammatory responses in dendritic cells and is known to limit the expression of type I IFNs and IFN signature genes in both human and murine macrophages. Elevated Foxo3 mRNA expression is associated with reduced severity of Crohn's disease and rheumatoid arthritis, and tumor- infiltrating dendritic cells are tolerogenic due to increased Foxo3 mRNA expression. This highlights the importance of Foxo3, and the control of its mRNA expression, in modulating inflammatory responses. Interestingly, preliminary analysis suggests that SLE patients fall into two distinct groups with respect to mRNA expression of Foxo3 and a cluster of associated genes (which we term the "Foxo3 signature"). Here, we will test the hypothesis that Foxo3 plays a protective role in lupus via the following Aims. In Aim 1, we will ask whether B cells that remain autoreactive after extensive BCR editing survive rather than undergo deletion in the absence of Foxo3. We will study editing and deletion in Foxo3-/- mice using a PCR assay of RS recombination, a measure of receptor editing, and an Ig Tg model in which autoreactive B cells are deleted. In Aim 2, we will determine whether mice that are prone to develop lupus have more severe disease in the absence of Foxo3, and if so which cell types mediate this effect. In Aim 3, we will compare SLE patients expressing low vs. high levels of Foxo3 for gene expression profiles and clinical disease parameters to determine whether patients with high levels of Foxo3 and associated "signature" genes have an altered disease course. This work will deter- mine whether Foxo3 limits the severity of lupus and characterize a unique set of Foxo3 associated biomarkers for a subset of SLE patients. These studies will also pave the way for new therapeutic approaches that target Foxo3 or Foxo3 signature genes.