Mechanisms of Immunosuppressive Actions of Glucocorticoids

糖皮质激素的免疫抑制作用机制

• 批准号: 7192223
• 负责人: INEZ ROGATSKY
• 金额: $ 39.14万
• 依托单位: HOSPITAL FOR SPECIAL SURGERY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-15 至 2011-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7192223
• 关键词: Accounting; Adverse effects; Affect; Agonist; Anti-Inflammatory Agents; Anti-inflammatory; Autoimmune Diabetes; Autoimmune Diseases; Autoimmune Process; Autoimmune thyroiditis; Autoimmunity; Benign; Binding; Biochemical; Biological Assay; Biological Response Modifiers; Cause of Death; Cell physiology; Cells; Complex; Cultured Cells; Cytokine Gene; Data; Development; Diabetes Mellitus; Disease; Double Stranded RNA Virus; Double-Stranded RNA; Economic Burden; Fostering; Foundations; Gene Expression; Gene Targeting; Genes; Genetic Transcription; Glucocorticoid Receptor; Glucocorticoids; Goals; Health; Hormones; Hybrids; IRF3 gene; Immune; Immune response; Immune system; Immunity; Immunosuppression; Immunosuppressive Agents; In Vitro; Inflammatory; Interferons; Knock-out; Ligands; Link; Lupus; Measures; Mediating; Mediator of activation protein; Molecular; Monitor; Mus; NCOA2 gene; Nuclear Receptors; Numbers; Pathogenesis; Pathway interactions; Pharmaceutical Preparations; Phosphorylation; Physiological; Population; Production; Proteins; Recruitment Activity; Regulation; Repression; Response Elements; Role; Signal Pathway; Signal Transduction; Stimulus; Surface; Systemic Lupus Erythematosus; Testing; Therapeutic immunosuppression; Thyroiditis; Toll-like receptors; Trans-Activators; Transcription Factor AP-1; Viral; Virus; Woman; Work; Yeasts; base; cell type; clinically relevant; cofactor; cytokine; design; disability; glucocorticoid receptor-interacting protein 1; human IRF3 protein; human RIPK1 protein; human TIF2 factor; human TLR3 protein; immunoregulation; in vivo; insight; interferon regulatory factor-3; macrophage; novel; nuclear factor 1; promoter; response; steroid hormone receptor; transcription factor

DESCRIPTION (provided by applicant): Nearly 20% of the US population suffers from autoimmune diseases, which are among the top ten causes of death by disease for women under 65 and the 4th leading cause of disability. This also imposes a severe economic burden measured in billions of dollars. Therapies for many autoimmune disorders rely on glucocorticoids (GC) to inhibit the production of cytokines, such as interferons (IFN)a/¿, which are intimately linked to the pathogenesis of lupus, autoimmune diabetes and thyroiditis. Yet, serious side effects associated with GC use can outweigh the benefits of these otherwise effective and affordable drugs. Our long-term goal is to identify the key viewers and mechanisms of GC-mediated immunomodulation in health and disease, which is essential for developing more specific therapies for autoimmunity. GC signal through a ligand-dependent GC receptor, GR, which recruits accessory cofactors to regulate transcription. Specifically, GR-dependent repression of AP1- and NF-?B -responsive genes accounts for certain anti-inflammatory activities of GC. While additional regulators must mediate the profound GC-induced immunosuppression, their identity and mechanisms of action are obscure. We established a nuclear receptor cofactor, GR-interacting protein (GRIP)1 as a corepressor for GR: NF-?B and GR: AP1 repression complexes. Unexpectedly, a yeast 2-hybrid screen for GRIP1 Repression Domain interactors yielded Interferon Regulatory Factor (IRF)3, a key effector of innate immune responses downstream of Toll- like receptors (TLR)3/4 and an essential transactivator for IFN¿. The objective of this application is to decipher the functional interaction between GC and IRF3. We hypothesize that GRIP1 is an IRF3 cofactor with a role in IFN production and autoimmunity. We further propose that GR and IRF3 compete for GRIP1 such that hormone-activated GR, in addition to directly repressing AP1/NF-?B, sequesters GRIP1 away from IRF3; the resulting inhibition of IRF3-dependent transcription is potentially a critical yet unexplored component of GC immunosuppression. Conversely, in response to bacterial or viral TLR3/4 ligands, IRF3 not only enhances cytokine transcription directly, but also depletes GRIP1 from GR:AP1 and GR: NF-?B repression complexes thereby promoting an effective immune response. Our Specific Aims are to: (1) dissect the GRIP1:IRF3 interaction in vitro, in cells and in IRF3 complexes bound at the IFN-Stimulated Response Elements; (2) corroborate the relevance of this interaction by examining the cross-talk between GR and IRF3 in primary macrophages; (3) identify the role of GRIP1 in IRF3 transcription and, using GRIP1 KO mice, in innate immune responses to virus, or to dsRNA and bacterial LPS in vivo. The GRIP1:IRF3 interaction uncovered in an unbiased screen may have a broad physiological significance. We will explore a role of GRIP1 in the immune system and decipher associated transcriptional mechanisms operative at IRF3 target genes. This work should provide a molecular basis for a functional antagonism between GC and IFN, and help define IRF3 as a novel target for GR-mediated immunosuppression, ultimately aiding in the design of more specific drugs for autoimmunity.

描述（由申请人提供）：近20%的美国人口患有自身免疫性疾病，这是65岁以下妇女疾病死亡的十大原因之一，也是第四大致残原因。这也造成了以数十亿美元计的严重经济负担。许多自身免疫性疾病的治疗依赖于糖皮质激素（GC）来抑制干扰素（IFN）a/¿等细胞因子的产生，干扰素与狼疮、自身免疫性糖尿病和甲状腺炎的发病机制密切相关。然而，与GC使用相关的严重副作用可能超过这些有效和负担得起的药物的好处。我们的长期目标是确定gc介导的免疫调节在健康和疾病中的关键观察者和机制，这对于开发更特异性的自身免疫疗法至关重要。GC信号通过配体依赖的GC受体，GR，招募辅助因子来调节转录。具体来说，gr依赖性抑制AP1-和NF-？B -应答基因对胃癌具有一定的抗炎作用。虽然其他调节因子必须介导gc诱导的深度免疫抑制，但它们的身份和作用机制尚不清楚。我们建立了一个核受体辅助因子，GR相互作用蛋白（GRIP）1作为GR的辅助抑制因子：NF-？B和GR: AP1抑制复合物。出乎意料的是，GRIP1抑制域相互作用的酵母2杂交筛选产生了干扰素调节因子（IRF）3，它是Toll样受体（TLR）3/4下游先天免疫反应的关键效应因子，也是IFN¿的重要反激活因子。这个应用程序的目的是破译GC和IRF3之间的功能交互。我们假设GRIP1是IRF3的辅助因子，在IFN的产生和自身免疫中起作用。我们进一步提出GR和IRF3竞争GRIP1，这样激素激活的GR除了直接抑制AP1/NF-？B，使GRIP1远离IRF3；由此产生的对irf3依赖性转录的抑制可能是GC免疫抑制的一个关键但尚未被探索的组成部分。相反，在响应细菌或病毒的TLR3/4配体时，IRF3不仅直接增强细胞因子转录，还会从GR:AP1和GR: NF-？B抑制复合物从而促进有效的免疫反应。我们的具体目标是：(1)在体外、细胞内和结合ifn刺激反应元件的IRF3复合物中解剖GRIP1:IRF3的相互作用；(2)通过检测原代巨噬细胞中GR和IRF3之间的串扰来证实这种相互作用的相关性；(3)确定GRIP1在IRF3转录中的作用，并利用GRIP1 KO小鼠在体内对病毒、dsRNA和细菌LPS的先天免疫应答中发挥作用。在无偏筛选中发现的GRIP1:IRF3相互作用可能具有广泛的生理意义。我们将探索GRIP1在免疫系统中的作用，并破译IRF3靶基因的相关转录机制。这项工作将为GC和IFN之间的功能性拮抗提供分子基础，并有助于将IRF3定义为gr介导的免疫抑制的新靶点，最终有助于设计更特异性的自身免疫药物。