Toll‐like Receptor 9 Signaling Is Augmented in Systemic Sclerosis and Elicits Transforming Growth Factor β–Dependent Fibroblast Activation

作者：Feng Fang, Roberta Gonçalves Marangoni, Xingchun Zhou, Yang Yang, Boping Ye, Anna Shangguang, Wenjie Qin, Wenxia Wang, Swati Bhattacharyya, Jun Wei, Warren G. Tourtellotte, John Varga · 发表于：Arthritis & Rheumatology · 年份：2016 · DOI：10.1002/art.39655 · 被引用次数：67 · 研究领域：Systemic Sclerosis and Related Diseases、Multiple Sclerosis Research Studies、Effects of Radiation Exposure

OBJECTIVE: Although transforming growth factor β (TGFβ) is recognized as being a key trigger of fibroblast activation in systemic sclerosis (SSc), prominent innate immunity suggests that additional pathways contribute to disease persistence. Toll-like receptor 9 (TLR9) is implicated in autoimmunity and fibrosis; however, the expression, mechanism of action, and pathogenic role of TLR9 signaling in SSc remain uncharacterized. The aim of this study was to explore the expression, activity, and potential pathogenic role of TLR9 in the context of skin fibrosis in SSc and in mouse models of experimental fibrosis. METHODS: Expression and localization of TLR9 were evaluated in SSc skin biopsy specimens and explanted skin fibroblasts. Fibrotic responses elicited by type A CpG oligonucleotide and mitochondrial DNA (mtDNA) were examined in human skin fibroblasts by a combination of real-time quantitative polymerase chain reaction, Western blot analysis, transient transfection, immunofluorescence microscopy, and functional assays. Expression of TLR9 was examined in 2 distinct mouse models of experimental fibrosis. RESULTS: Skin biopsy specimens obtained from 2 independent cohorts of SSc patients showed up-regulation of TLR9, and myofibroblasts were the major cellular source. Moreover, SSc skin biopsy specimens showed evidence of TLR9 pathway activation. CpG induced robust TLR9-dependent fibrotic responses in explanted normal fibroblasts that could be blocked by bortezomib and were mediat...