Mechanisms of Immunosuppressive Actions of Glucocorticoids

近20%的美国人患有自身免疫性疾病，这些疾病位居十大病因之列 65岁以下妇女因疾病死亡的比例最高，是导致残疾的第四大原因。这也导致了一种严重的 以数十亿美元衡量的经济负担。许多自身免疫性疾病的治疗依赖于葡萄糖- 皮质激素(GC)，以抑制细胞因子的产生，如干扰素(干扰素)a/(J)，它们与 与狼疮、自身免疫性糖尿病和甲状腺炎的发病机制有关。然而，与此相关的严重副作用 对于GC，使用可能超过这些本来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，这是必不可少的 为自身免疫开发更特效的治疗方法。GC信号通过配体依赖的GC受体GR， 它招募辅助辅助因子来调节转录。具体地说，依赖GR抑制AP1- NFxB反应基因与GC的抗炎活性有关。虽然更多的监管机构 必须介导GC诱导的深层免疫抑制，其身份和作用机制尚不清楚。我们 建立了核受体辅因子GR相互作用蛋白(GRIP)L作为GR：NFkB和GR： API抑制复合体。出人意料的是，酵母双杂交筛选出了GRIP1阻遏结构域的相互作用 产生了干扰素调节因子(IRF)3，Toll下游天然免疫反应的关键效应因子- 样受体(TLR)3/4和IFNp的重要反式激活因子。这个应用程序的目标是破译 GC与IRF3的功能相互作用。我们假设GRIP1是一个在干扰素中起作用的IRF3辅助因子 生产和自身免疫力。Wefurther提出，Grand IRF3竞争GRIP1，从而激素- 激活的GR，除了直接抑制APL/NFicB外，还将GRIP1与IRF3隔离；由此产生的 抑制IRF3依赖的转录可能是GC免疫的一个关键但尚未被探索的成分。 压制。相反，在对细菌或病毒TLR3/4配体的反应中，IRF3不仅增强细胞因子 直接转录，但也消耗GR：AP1和GR：NFX：B阻遏复合体中的GRIP1 促进有效的免疫反应。我们的具体目标是：(1)剖析GRIP1：IRF3在 体外、细胞内和与干扰素刺激的反应元件结合的IRF3复合体中；(2)证实 通过检查初级巨噬细胞中Grand IRF3之间的串扰来研究这种相互作用的相关性；(3) 确定GRIP1在IRF3转录中的作用，并使用GRIP1KO小鼠，在先天免疫反应中的作用 病毒，或体内对dsRNA和细菌内毒素的作用。在无偏屏幕中发现的GRIP1：IRF3相互作用可以 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 作用于IRF3靶基因的相关转录机制。这项工作应该提供一种分子 为GC和干扰素之间的功能拮抗奠定基础，并有助于将IRF3定义为GR-2的新靶点 介导免疫抑制，最终帮助设计更具特异性的自身免疫药物。

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 ofdollars. Therapies for many autoimmune disorders rely on gluco- corticoids (GC)to inhibit the production of cytokines, such as interferons (IFN)a/ (J,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 therapiesfor autoimmunity. GC signal through a ligand-dependent GC receptor, GR, which recruits accessory cofactors to regulate transcription. Specifically, GR-dependent repression of AP1- and NFxB-responsive genes accounts for certain anti-inflammatory activities of GC. While additional regulators must mediate the profound GC-induced immunosuyyression, their identity and mechanisms ofaction are obscure. We established a nuclear receptor cofactor, GR-interacting protein (GRIP)l as a corepressor for GR:NFKB and GR: API 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 ofToll- like receptors (TLR)3/4 and an essential transactivator for IFNp. Theobjective ofthis application is to decipher the functional interaction between GC and IRF3. Wehypothesize that GRIP1 is an IRF3 cofactor with a role in IFN production and autoimmunity. Wefurther propose that GRand IRF3 competefor GRIP1 such that hormone- activated GR,in addition to directly repressing APl/NFicB,sequesters GRIP1 away from IRF3; the resulting inhibition of IRF3-dependent transcription is potentially a critical yet unexplored component of GC immuno- suppression. Conversely, in response to bacterial or viral TLR3/4 ligands, IRF3 not only enhances cytokine transcription directly, but also depletes GRIP1 from GR:AP1and GR:NFx: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 GRand IRF3 in primary macrophages; (3) identify the role of GRIP1 in IRF3 transcription and,using GRIP1KO mice, in innate immune responses to virus, or to dsRNA and bacterial LPS in vivo. The GRIP1:IRF3interaction uncovered in an unbiased screen may have a broad physiological significance. We will explore a role of GRIP1in 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.