Damage-Associated Molecular Patterns Driving Fibrosis Progression in Scleroderma

2018年6月3日 摘要 多器官同步纤维化是系统性硬化症（SSc）的标志，但其 发病机制仍然知之甚少，迫切需要发现“可用药”的靶点。 模式识别受体Toll样受体4（TLR 4）是先天免疫的重要介质， 在免疫细胞和基质细胞上表达，并且可以被称为 “损伤相关分子模式”（DAMP）。我们的已发表和初步工作 实验室表明，TLR 4及其内源性配体腱生蛋白-C可能在 多器官纤维化。值得注意的是，腱生蛋白-C本身激发核心纤维化反应，包括ECM 在成纤维细胞和3D人类皮肤类器官模型中产生和基质硬化。TLR 4活性 由泛素编辑酶A20调节，这是SSc的主要风险基因。但 与Ssc相关的A20变体和发病机制的联系尚不清楚。我们证明 在SSc皮肤活检中A20表达减少。令人惊讶的是，我们发现A20抑制了核心 纤维化反应，而A20单倍型不足的小鼠表现出明显加重的非纤维化反应。 炎症性皮肤纤维化我们假设SSc中纤维化的持续性可以解释为 活化的TLR 4信号传导由生腱蛋白-C和其他DAMP触发，并长期持续 A20功能受损具有增加的促纤维化TLR 4途径活性的细胞类型，以及具有增加的促纤维化TLR 4途径活性的细胞类型。 促纤维化DAMP和特定结构域的集合仍然未知。此外，临床 SSc中A20减少、A20的细胞类型特异性调节和抗纤维化活性以及 A20减少和SSc发病机制的联系从未被研究过。解决 这些关键的差距，目标1将确定细胞类型和刺激特异性的作用和机制， 两种不同的实验诱导多器官纤维化模型中的DAMP-TLR 4信号传导;图 关键的腱生蛋白-C结构域，并鉴定作为潜在SSc生物标志物和治疗剂的其他DAMP 目标2将定义SSc纵向队列中A20表达的临床相关性 并使用新的A20缺陷型和A20抑制型来定义A20在纤维化过程中的不同功能。 人源化BAC转基因小鼠。目的3确定TLR 4的细胞来源和功能 SSc患者和对照的皮肤和肺中的信号传导途径活性。利用人类疾病 来自西北大学和耶鲁大学硬皮病项目的样本，结合体外 以及体内疾病模型和最先进的技术， 分析和公正的单细胞RNA测序的多个组织，我们的研究团队准备 在理解SSc中TLR 4信号传导方面取得了显著进展。这些信息反过来将 指导发现新的生物标志物和疗法。

June 3 2018 ABSTRACT Synchronous fibrosis in multiple organs is the defining hallmark of systemic sclerosis (SSc), but its pathogenesis remains poorly understood, and there is an urgent need to discover “druggable” targets. The pattern recognition receptor Toll-like receptor 4 (TLR4), a vital mediator of innate immunity, is expressed on both immune and stromal cells, and can be activated by endogenous ligands called “damage-associated molecular patterns” (DAMPs). Published and preliminary work from our laboratories show that TLR4 and its endogenous ligand tenascin-C are likely to play important roles in multi-organ fibrosis in SSc. Notably, tenascin-C itself elicits core fibrotic responses including ECM production and matrix stiffening in fibroblasts and 3D human skin organoid models. TLR4 activity is regulated by the ubiquitin-editing enzyme A20, which is a major risk gene for SSc. However, the mechanism linking SSc-associated A20 variants and pathogenesis are unknown. We demonstrated that A20 expression is reduced in SSc skin biopsies. Surprisingly, we found that A20 inhibited core fibrotic responses, and mice that are haploinsufficient for A20 showed markedly aggravated non- inflammatory skin fibrosis. We hypothesize that persistence of fibrosis in SSc could be explained by activated TLR4 signaling that is triggered by tenascin-C and other DAMPs, and chronically sustained by impaired A20 function. The cell types with increased profibrotic TLR4 pathway activity, and the ensemble of profibrotic DAMPs and specific domains, remain unknown. Moreover, the clinical correlates of reduced A20 in SSc, cell type-specific regulation and anti-fibrotic activity of A20, and the mechanisms linking reduced A20 and SSc pathogenesis, have never been investigated. To address these critical gaps, Aim 1 will determine cell type- and stimulus-specific roles and mechanisms of DAMP-TLR4 signaling in two separate models of experimentally-induced multi-organ fibrosis; map key tenascin-C domains and identify additional DAMPs as potential SSc biomarkers and therapeutic targets; Aim 2 will define the clinical correlates of A20 expression in a longitudinal cohort of SSc patients; and define distinct functions of A20 in the fibrotic process using novel A20-deficient and A20 humanized BAC transgenic mice. Aim 3 will determine the cellular sources and function of TLR4 signaling pathway activity in skin and lung from SSc patients and controls. Employing human disease samples from the established Northwestern and Yale Scleroderma Programs, combined with in vitro and in vivo disease models and state-of-the-art technologies including comprehensive matrisome analysis and unbiased single cell RNA sequencing of multiple tissue, our investigative team is poised to generate notable advances in understanding TLR4 signaling in SSc. The information in turn will guide discovery of novel biomarkers and therapies.