Bryon Jessica, Wasson Christopher W, Koeppen Katja, Chandler Francesca, Willis Leon F, Di Donato Stefano, Klein Elliott, Zeqiraj Elton, Ross Rebecca L, Del Galdo Francesco
University of Leeds, Leeds, United Kingdom.
Boehringer Ingelheim, Ridgefield, Connecticut.
Arthritis Rheumatol. 2025 Mar;77(3):322-334. doi: 10.1002/art.43029. Epub 2024 Nov 12.
Activation of type I interferon (IFN) response has been shown to correlate with disease activity in systemic sclerosis (SSc). It is currently unknown whether the tissue-specific type I IFN activation is a consequence of the response observed in blood or rather its source. Exosomes from SSc fibroblasts were recently shown to activate macrophages in vitro. Here, we aimed to determine the source of type I IFN signature in SSc skin biopsies and the potential role of exosomes from SSc dermal fibroblasts in the process.
Skin biopsies were obtained from the forearms of healthy patients and of those with SSc and processed for dermal fibroblasts and keratinocytes. Exosomes were isolated from healthy and SSc dermal fibroblast supernatants by ultracentrifugation and added to human skin keratinocytes. Keratinocyte transcriptome was analyzed by RNA sequencing (RNA-seq) analysis. TANK-binding kinase (TBK) and JAK were inhibited using a small molecule inhibitor (GSK8612) and tofacitinib, respectively.
SSc skin biopsies showed the highest levels of type I IFN response in the epidermal layer. RNA-seq analysis of keratinocytes transcriptome following exposure to dermal fibroblast exosomes showed strong up-regulation of IFN signature genes induced by SSc exosomes compared to healthy control. Inhibition of TBK or JAK activity suppressed the up-regulation of the IFN signature induced by SSc exosomes.
IFN activation of SSc keratinocytes is dependent on their crosstalk with dermal fibroblasts and inducible by extracellular exosomes. Our data indicate that SSc fibroblast exosomes contribute to the type I IFN activation in SSc skin through activation of pattern recognition receptors upstream of TBK.
I型干扰素（IFN）反应的激活已被证明与系统性硬化症（SSc）的疾病活动相关。目前尚不清楚组织特异性I型干扰素激活是血液中观察到的反应的结果还是其来源。最近发现SSc成纤维细胞来源的外泌体可在体外激活巨噬细胞。在此，我们旨在确定SSc皮肤活检中I型干扰素特征的来源以及SSc真皮成纤维细胞来源的外泌体在此过程中的潜在作用。
从健康患者和SSc患者的前臂获取皮肤活检样本，并对真皮成纤维细胞和角质形成细胞进行处理。通过超速离心从健康和SSc真皮成纤维细胞上清液中分离出外泌体，并将其添加到人皮肤角质形成细胞中。通过RNA测序（RNA-seq）分析角质形成细胞转录组。分别使用小分子抑制剂（GSK8612）和托法替布抑制TANK结合激酶（TBK）和JAK。
SSc皮肤活检显示表皮层中I型干扰素反应水平最高。与健康对照相比，角质形成细胞转录组在暴露于真皮成纤维细胞外泌体后的RNA-seq分析显示，SSc外泌体诱导的IFN特征基因强烈上调。抑制TBK或JAK活性可抑制SSc外泌体诱导的IFN特征上调。
SSc角质形成细胞的IFN激活依赖于它们与真皮成纤维细胞的相互作用，并可由细胞外外泌体诱导。我们的数据表明，SSc成纤维细胞外泌体通过激活TBK上游的模式识别受体，促进了SSc皮肤中的I型干扰素激活。
