Mechanisms by which TLR9-deficiency and FasL Promote Cutaneous Lupus

TLR9 缺陷和 FasL 促进皮肤狼疮的机制

• 批准号: 9884735
• 负责人: Ann Marshak-Rothstein
• 金额: $ 20.94万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-05 至 2022-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9884735
• 关键词: Address; Animal Model; Apoptosis; Autoantibodies; Autoimmune Diseases; Autoimmunity; Automobile Driving; B-Lymphocytes; Basement membrane; Binding; Biopsy; CASP8 gene; CCL8 gene; Cell Death; Cells; Cessation of life; Chimeric Proteins; Clinical; Cutaneous; Data; Dendritic Cells; Deposition; Dermal; Dermatitis; Development; Disease; Exhibits; Flare; Functional disorder; Gene Expression; Gene Targeting; Generations; Goals; Hematopoietic; Histologic; Immunosuppressive Agents; In Vitro; Inflammation; Inflammatory; Interferon Type II; Interleukin-17; Langerhans cell; Ligands; Lupus; MHC Class II Genes; Membrane; Modeling; Molecular Chaperones; Mus; Mutation; Myeloid Cells; Pathogenesis; Pathway interactions; Patients; Process; Production; Psoriasis; Radiation Chimera; Recurrence; Regulation; Reproducibility; Role; Signal Pathway; Signal Transduction; Site; Skin; Structure of germinal center of lymph node; System; T-Lymphocyte; TLR7 gene; Th1 Cells; Tissues; Treatment Efficacy; UV Radiation Exposure; Up-Regulation; Work; chemokine; cytokine; draining lymph node; effector T cell; human disease; in vivo; insight; keratinocyte; lupus cutaneous; lupus-like; mouse model; novel; patient population; prevent; protein expression; radioresistant; response; side effect; skin lesion; skin organogenesis; small molecule inhibitor; therapeutic target; trafficking

ABSTRACT Common pathophysiological mechanisms are thought to promote the cutaneous and systemic manifestations of lupus. Thus a better understanding of the factors that promote CLE are likely to provide important insights as far as the pathogenesis of SLE. Nevertheless, it is also likely that tissue specific effector mechanisms account for the diverse clinical presentations exhibited by SLE patient populations. Since 75% of SLE patients exhibit skin lesions of some sort, and UV exposure of the skin is often associated with lupus flares, it is surprising that there have been relatively few mechanistic studies that address initiation, progression and recurrence of CLE. One reason for this gap is that murine models available for the study of CLE have been limited – despite the numerous murine models of SLE, models that accurately reflect the central features of CLE are much more limited. We have now develop an inducible model of lupus like skin inflammation (LLSI), initiated by T cell transfer, that recapitulates many of the features of CLE. These include a prominent role for skin-infiltrating IFNγ-producing Th1 cells, excessive keratinocyte death, autoantibody deposition at the dermal/epidermal border, increased expression of CxCL9, CxCL10, CxCL11, CCL8, and accumulation of pDCs in the skin. There are also mechanistic similarities between our LLSI model and other inducible as well as genetically programmed murine models of SLE; they all depend on the expression of TLR7 and are exacerbated by the absence of TLR9. Therefore our LLSI mice provide a novel, rapid and reproducible system for exploring the effector mechanisms responsible for the induction and regulation of cutaneous lupus. This application will focus on TLR9 and FasL. As mentioned, TLR9 negatively regulates the development of both cutaneous and systemic lupus, but whether TLR9 works passively by simply competing with TLR7 for access to the endosomal trafficking chaperone Unc93B1, or actively by inducing molecules dependent on a TLR9 signaling cascade that limit inflammation, has not been addressed. We have also recently shown that the development of skin lesions is completely dependent T cell FasL expression, but whether FasL promotes disease indirectly by inducing cell death and creating cell debris and/or directly by inducing the production of pro-inflammatory cytokines is unresolved. Interplay between TLR9 and FasL may be an important amplification loop in LLSI - TLR ligands induce upregulation of Fas and FasL generates cell debris that can activate endosomal TLRs. We propose to address the questions by using gene-targeted mice with discriminating mutations for both in vitro and in vivo (LLSI) studies. In Aim 1, we will use mice that express normal levels of a form of TLR9 that cannot engage MyD88, and in Aim 2, we will use mice that express a Caspase 8 mutation which removes the Caspase 8 autocleavage site and thereby prevents FasL-induced apoptosis but not chemokine production. Together, these studies should help identify the most effective therapeutic strategies for targeting TLR9 and FasL pathways to prevent or ameliorate the development of cutaneous lupus.

抽象的 常见的病理生理机制被认为促进皮肤和全身表现 狼疮。因此，更好地了解促进 CLE 的因素可能会提供重要的见解： 就SLE的发病机制而言。然而，组织特异性效应机制也可能解释了这一点。 针对 SLE 患者群体表现出的不同临床表现。由于 75% 的 SLE 患者表现出 某种类型的皮肤损伤，并且皮肤的紫外线暴露通常与狼疮发作有关，令人惊讶的是 针对 CLE 的发生、进展和复发的机制研究相对较少。 造成这一差距的原因之一是可用于 CLE 研究的小鼠模型有限——尽管 SLE 小鼠模型众多，准确反映 CLE 核心特征的模型还有更多 有限的。我们现在开发了一种由 T 细胞引发的狼疮样皮肤炎症 (LLSI) 的诱导模型 转移，概括了 CLE 的许多功能。其中包括皮肤渗透的重要作用 产生 IFNγ 的 Th1 细胞、角质形成细胞过度死亡、自身抗体沉积在真皮/表皮 边界，CxCL9、CxCL10、CxCL11、CCL8 表达增加以及皮肤中 pDC 的积累。那里 我们的 LLSI 模型与其他诱导模型和遗传模型之间也存在机械相似性 SLE 的编程小鼠模型；它们都依赖于 TLR7 的表达，并因 TLR7 的表达而加剧 TLR9 缺失。因此，我们的 LLSI 小鼠提供了一种新颖、快速且可重复的系统来探索 负责诱导和调节皮肤狼疮的效应机制。该应用程序将 重点关注 TLR9 和 FasL。如前所述，TLR9 负向调节皮肤和皮肤的发育。 系统性狼疮，但 TLR9 是否只是通过简单地与 TLR7 竞争访问 内体运输伴侣 Unc93B1，或通过依赖 TLR9 信号传导的分子主动诱导 限制炎症的级联反应尚未得到解决。我们最近还表明，发展 皮肤病变的发生完全依赖于T细胞FasL表达，但FasL是否间接促进病变 通过诱导细胞死亡和产生细胞碎片和/或直接通过诱导促炎物质的产生 细胞因子尚未解决。 TLR9 和 FasL 之间的相互作用可能是 LLSI 中重要的放大环路 - TLR 配体诱导 Fas 上调，FasL 产生可激活内体 TLR 的细胞碎片。我们 建议通过使用具有区分性突变的基因靶向小鼠来解决这些问题 和体内（LLSI）研究。在目标 1 中，我们将使用表达正常水平 TLR9 形式的小鼠，而这种 TLR9 形式不能表达正常水平。 参与 MyD88，在目标 2 中，我们将使用表达 Caspase 8 突变的小鼠，该突变消除了 Caspase 8 自动切割位点，从而阻止 FasL 诱导的细胞凋亡，但不能阻止趋化因子的产生。 总之，这些研究应有助于确定针对 TLR9 和 TLR9 的最有效的治疗策略。 FasL 途径可预防或改善皮肤狼疮的发展。