Interferon Regulatory Factor 7 Links Interferon Pathway Activation to the Exaggerates Fibrotic Response in Systemic Sclerosis

系统性硬化症(SSc)是一种多系统自身免疫性、纤维性疾病。 发病率和死亡率。系统性硬化症的有效治疗方法的开发进展受到了 对其发病机制的认识支离破碎。尽管大量证据表明免疫功能失调 在SSC中，免疫系统影响成纤维细胞功能的机制尚不清楚。我们 提出了一种多方面的方法来阐明干扰素调节因子7(IRF7)在皮肤中的作用 成纤维细胞作为SSC免疫失调和纤维化之间的病理桥梁。 干扰素(干扰素)基因表达特征是最显著的外周血细胞转录谱 SSC.此外，我们的大规模基因表达研究已经确定了IRF7，一个在细胞周期中的关键转录因子 I型干扰素途径，作为皮肤和血液中SSc分子图谱的最高预测上游调节因子， 以及SSC成纤维细胞的重要调节因子。我们最近发表的工作表明，IRF7显著地 SSC皮肤和移植的真皮成纤维细胞上调和激活I型干扰素上调IRF7 在成纤维细胞中表达。IRF7与Smad3相互作用并增强转化生长因子β诱导的肝纤维化信号转导 成纤维细胞。此外，在两种小鼠皮肤纤维化模型中，全球IRF7基因敲除可减轻皮肤纤维化。 最后，我们最近的初步数据表明，成纤维细胞特异性的IRF7基因敲除可能足以减弱 博莱霉素性真皮纤维化。在此，我们假设I型干扰素途径与纤维化有关。 通过增强转化生长因子β信号在成纤维细胞中的反应，成纤维细胞是干细胞中的主要效应细胞。我们的初选 目的是阐明I型干扰素诱导的irf7上调在增强转化生长因子β规范中的作用。 真皮成纤维细胞中IRF7与Smad3相互作用途径的研究将致力于实现以下具体目标： 目的1：明确IRF7缺失在小鼠皮肤纤维化模型中对成纤维细胞的特异性贡献。这个 成纤维细胞特异性IRF7缺失对博莱霉素性真皮纤维化和Tsk1真皮纤维化的影响 将对模型进行调查。目的2：阐明IRF7在Smad3介导的功能中的作用 含IRF7基因的人成纤维细胞系转录活性及基因表达调控 会产生表达缺失和转化生长因子β介导的Smad3转录靶点和基因 表达调控将通过芯片和RNA测序来表征。目标3：勾勒出关系 外周血细胞干扰素信号与终末器官水平IRF7上调之间的关系 自发性硬化症患者。系统性红斑狼疮患者外周血中干扰素标志物与IRF7表达的关系 皮肤组织和真皮成纤维细胞亚群将使用散装和单细胞RNA测序来表征。 总而言之，这一建议可以阐明免疫失调导致IRF7的关键机制 活化增强了SSC的纤维化反应。最终，这可以打开识别更多 针对这种潜在破坏性疾病的有针对性和有效的治疗选择。

Systemic sclerosis (SSc-scleroderma) is a multisystem autoimmune, fibrotic disease associated with high morbidity and mortality. Progress in the development of effective therapies for SSc has been hampered by a fragmented understanding of its pathogenesis. Although abundant evidence implicates dysregulated immunity in SSc, the mechanisms by which the immune system influences fibroblast function are not well-understood. We propose herein a multifaceted approach to elucidate the role of interferon regulatory factor 7 (IRF7) in dermal fibroblasts as a pathologic bridge between immune dysregulation and fibrosis in SSc. An interferon (IFN) gene expression signature is the most prominent peripheral blood cell transcript profile in SSc. Moreover, our large-scale gene expression studies have identified IRF7, a key transcription factor in the type I IFN pathway, as the top predicted upstream regulator of the SSc molecular profile in both skin and blood, as well as a prominent regulator of SSc fibroblasts. Our recently published work showed that IRF7 is significantly upregulated and activated in SSc skin and explanted dermal fibroblasts, and that type I IFN upregulates IRF7 expression in fibroblasts. IRF7 interacts with SMAD3 and potentiates TGFβ induced fibrosis signaling in fibroblasts. Moreover, global Irf7 knockdown attenuates dermal fibrosis in two murine dermal fibrosis models. Lastly, our recent preliminary data suggest fibroblast specific Irf7 knockdown might be sufficient for attenuating the bleomycin induced dermal fibrosis. Herein, we hypothesize that IRF7 links type I IFN pathway to the fibrotic response by potentiating the TGFβ signaling in fibroblasts which are the primary effector cells in SSc. Our primary goal is to elucidate the role of type I IFN induced IRF7 upregulation in potentiating the TGFβ canonical pathway via IRF7 interaction with SMAD3 in dermal fibroblasts. The following Specific Aims will be pursued: Aim 1: Define the fibroblast specific contribution of Irf7 depletion in murine dermal fibrosis models. The impact of fibroblast specific Irf7 depletion on dermal fibrosis in bleomycin induced and Tsk1 dermal fibrosis models will be investigated. Aim 2: Elucidate the functional effects of IRF7 on SMAD3 mediated transcriptional activity and gene expression regulation Human fibroblast cell lines with IRF7 over- expression and deletion will be generated and TGFβ-mediated SMAD3 transcriptional targets and gene expression regulation will be characterized by ChIP- and RNA-sequencing. Aim 3: Delineate the relationship between the peripheral blood cell interferon signature and IRF7 upregulation at the end-organ level in patients with SSc. The relationship between the peripheral blood IFN signature and IRF7 expression in SSc skin tissue and dermal fibroblast subpopulations will be characterized using bulk and single cell RNA sequencing. Cumulatively, this proposal can elucidate a key mechanism by which immune dysregulation leading to IRF7 activation potentiates the fibrotic response in SSc. Ultimately, this can open the door to identification of more targeted and effective treatment options for this potentially devastating disease.