Activation of Innate Immunity by Small Ribonucleoprotein

小核糖核蛋白激活先天免疫

• 批准号: 7278714
• 负责人: WESTLEY H REEVES
• 金额: $ 27.93万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-16 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7278714
• 关键词: Amino Acid Motifs; Antibody Formation; Antigens; Antiviral Agents; Antiviral Response; Autoantibodies; Autoantigens; Autoimmune Responses; Autoimmunity; B-Cell Activation; B-Cell Development; B-Lymphocytes; Binding; Binding Proteins; Blood Circulation; Cell Maturation; Cells; Data; Dendritic Cells; Double-Stranded RNA; Exposure to; Gene Expression; Genes; Immune; Immunity; Interferon Type I; Interferons; Lead; Lupus; Lupus Erythematosus; Macrophage Activation; Mediating; Mononuclear; Natural Immunity; Normal Cell; Pathogenesis; Pathway interactions; Patients; Pattern Recognition; Peripheral Blood Mononuclear Cell; Play; Production; Protein Binding; Proteins; Purpose; RNA; RNA Viruses; RNA-Protein Interaction; Relative (related person); Ribonucleoproteins; Role; Series; Signal Transduction; Small Nuclear Ribonucleoproteins; Small RNA; Structure; System; Systemic Lupus Erythematosus; T-Lymphocyte; Testing; Therapeutic Uses; U1 Small Nuclear Ribonucleoprotein; U1 small nuclear RNA; Viral; Work; autoreactive B cell; autoreactive T cell; cell type; chronic autoimmune disease; cytokine; eIF-2 Kinase; gain of function; human TLR3 protein; macrophage; microbial; monocyte; prevent; response; sensor; stem

DESCRIPTION (provided by applicant): Many patients with chronic autoimmune diseases such as systemic lupus erythematosus (SLE) develop autoantibodies to ubiquitous host cellular molecules, such as Sm small ribonucleoproteins (snRNPs) containing the small RNAs U1, U2, U4-6, and U5 RNAs. These small RNAs are highly structured molecules containing extensive regions of duplex (double-stranded, ds) RNA. High concentrations of dsRNA produced by replicating RNA viruses activate innate immunity by binding to dsRNA binding proteins such as TLR3 and/or the dsRNA dependent protein kinase (PKR), causing increased production of type I interferon (IFN) leading to an antiviral response. The purpose of this project is to elucidate the mechanism by which snRNP activates innate immunity in systemic lupus erythematosus (SLE). Mononuclear cells from SLE patients with increased anti-snRNPs autoantibodies express higher levels of genes usually induced by type-I IFN, an innate cytokine that plays a key role in SLE. Additional preliminary data show that double-stranded (ds) U1 RNA from snRNP stimulates mononuclear cells to activate dsRNA-induced protein kinase (PKR), a hallmark of the IFN response. It is hypothesized that snRNP triggers IFN production by engaging Toll-like receptor 3 (TLR3) in innate immune cells via U1 RNA. Preliminary studies indicated that peripheral blood mononuclear cells from a subset of patients with autoantibodies against the small ribonucleoproteins nRNP/Sm and Ro/La express higher levels of IFN inducible genes than healthy controls or the subset of lupus patients who are negative for these autoantibodies. Moreover, it was found that purified authentic U1 RNA and synthetic stem-loop II of U1 are potent stimulators of IFN-inducible gene expression and PKR autophosphorylation. Interestingly, type I IFNs also have been implicated in the pathogenesis of SLE. We hypothesize that the small RNAs associated with U1 snRNPs promote autoimmune responses to the protein components of UI snRNPs by stimulating signaling via TLR3 and/or PKR. By stimulating type I IFN production, highly structured small RNAs of cellular origin may promote dendritic cell maturation and activation of autoreactive T cells and/or the activation and maturation of autoreactive B cells specific for snRNPs. Three Specific Aims are proposed. Aim I is to examine how U1 RNA stimulates an antiviral (IFN) response by investigating whether the IFN response is mediated by TLR3 signaling, internalization of the U1 RNA followed by binding and activation of PKR, or some other pathway. The portion(s) of U1 RNA responsible for the immunostimulatory effect will be identified and the possibility that immunoinhibitory dsRNAs also exist will be examined. Aim 2 is to determine what normally prevents endogenous U1 RNA from activating the IFN system. It is hypothesized that proteins bound to structured regions of the RNA prevent it from engaging TLR3 or PKR. The ability of series of partially disrupted U1 snRNP fractions to stimulate IFN responses or PKR activation will be examined. Aim 3 is to identify the cell type that becomes activated in response to U1 RNA. The effects of U1 RNA on dendritic cell maturation, macrophage activation, and B cell development will be determined. These studies may lead to a better understanding of why autoimmune responses in SLE selectively target the Sm (U series) and other snRNPs. By triggering innate immunity, the highly structured, RNAs contained in these molecules could promote autoimmunity by promoting dendritic cell maturation and/or the activation of autoreactive B or T lymphocytes.

描述（由申请人提供）： 许多患有慢性自身免疫性疾病（如系统性红斑狼疮（SLE））的患者产生针对普遍存在的宿主细胞分子（如含有小RNA U1、U2、U4-6和U 5 RNA的Sm小核糖核蛋白（snRNP））的自身抗体。这些小RNA是高度结构化的分子，含有广泛的双链体（双链，ds）RNA区域。通过复制RNA病毒产生的高浓度dsRNA通过与dsRNA结合蛋白如TLR 3和/或dsRNA依赖性蛋白激酶（PKR）结合来激活先天免疫，引起I型干扰素（IFN）的产生增加，从而导致抗病毒应答。本研究的目的是阐明snRNP激活系统性红斑狼疮（SLE）先天免疫的机制。 来自具有增加的抗snRNP自身抗体的SLE患者的单核细胞表达通常由I型IFN诱导的更高水平的基因，I型IFN是在SLE中起关键作用的先天性细胞因子。 额外的初步数据显示，来自snRNP的双链（ds）U1 RNA刺激单核细胞激活dsRNA诱导的蛋白激酶（PKR），这是IFN应答的标志。 假设snRNP通过U1 RNA与先天性免疫细胞中的Toll样受体3（TLR 3）结合来触发IFN产生。 初步研究表明，外周血单核细胞的一个子集的患者与自身抗体对小核糖核蛋白nRNP/Sm和Ro/La表达更高水平的IFN诱导基因比健康对照组或狼疮患者的子集谁是这些自身抗体阴性。此外，研究发现纯化的真实U1 RNA和合成的U1茎环II是IFN诱导的基因表达和PKR自磷酸化的有效刺激物。有趣的是，I型IFN也与SLE的发病机制有关。我们假设与U1 snRNP相关的小RNA通过TLR 3和/或PKR刺激信号传导促进对UI snRNP蛋白组分的自身免疫反应。通过刺激I型IFN产生，细胞来源的高度结构化的小RNA可以促进树突细胞成熟和自身反应性T细胞的活化和/或对snRNP特异性的自身反应性B细胞的活化和成熟。提出了三个具体目标。目的我是研究如何U1 RNA刺激抗病毒（IFN）的反应，通过调查是否介导的干扰素的反应是由TLR 3信号，内化的U1 RNA结合和激活PKR，或其他一些途径。将鉴定负责免疫刺激作用的U1 RNA部分，并检查免疫抑制性dsRNA也存在的可能性。目的2是确定通常阻止内源性U1 RNA激活IFN系统。据推测，与RNA结构化区域结合的蛋白质阻止其与TLR 3或PKR结合。将检查一系列部分破坏的U1 snRNP组分刺激IFN应答或PKR活化的能力。目的3是鉴定响应于U1 RNA而被激活的细胞类型。将确定U1 RNA对树突状细胞成熟、巨噬细胞活化和B细胞发育的影响。这些研究可能会导致更好地理解为什么SLE的自身免疫反应选择性靶向Sm（U系列）和其他snRNP。通过触发先天免疫，这些分子中所含的高度结构化的RNA可以通过促进树突细胞成熟和/或自身反应性B或T淋巴细胞的活化来促进自身免疫。