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

Feng Fang, Roberta Goncalves Marangoni, Xingchun Zhou, Yang Yang, Boping Ye, Anna Shangguang, Wenjie Qin, Wenxia Wang, Swati Bhattacharyya, Jun Wei, Warren G. Tourtellotte, John Varga*

*Corresponding author for this work

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

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 mediated through the action of endogenous TGFβ. Mice with experimental fibrosis showed a time-dependent increase in TLR9 localized primarily to myofibroblasts in the dermis. Conclusion: In isolated fibroblasts, TLR9 elicits fibrotic responses mediated via endogenous TGFβ. In patients with SSc, mtDNA and other damage-associated TLR9 ligands in the skin might trigger localized activation of TLR9 signaling, TGFβ production, and consequent fibroblast activation. Disrupting this fibrotic process with inhibitors targeting TLR9 or its downstream signaling pathways might therefore represent a novel approach to SSc therapy.

Original languageEnglish (US)
Pages (from-to)1989-2002
Number of pages14
JournalArthritis and Rheumatology
Volume68
Issue number8
DOIs
StatePublished - Aug 1 2016

Fingerprint

Toll-Like Receptor 9
Systemic Scleroderma
Transforming Growth Factors
Fibroblasts
Skin
Fibrosis
Myofibroblasts
Mitochondrial DNA
Biopsy
Theoretical Models
Dermis
Autoimmunity
Fluorescence Microscopy
Innate Immunity
Oligonucleotides

ASJC Scopus subject areas

  • Immunology and Allergy
  • Rheumatology
  • Immunology

Cite this

Fang, Feng ; Goncalves Marangoni, Roberta ; Zhou, Xingchun ; Yang, Yang ; Ye, Boping ; Shangguang, Anna ; Qin, Wenjie ; Wang, Wenxia ; Bhattacharyya, Swati ; Wei, Jun ; Tourtellotte, Warren G. ; Varga, John. / Toll-like Receptor 9 Signaling Is Augmented in Systemic Sclerosis and Elicits Transforming Growth Factor β–Dependent Fibroblast Activation. In: Arthritis and Rheumatology. 2016 ; Vol. 68, No. 8. pp. 1989-2002.
@article{7993ef2985264065994fb0986e6a7f50,
title = "Toll-like Receptor 9 Signaling Is Augmented in Systemic Sclerosis and Elicits Transforming Growth Factor β–Dependent Fibroblast Activation",
abstract = "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 mediated through the action of endogenous TGFβ. Mice with experimental fibrosis showed a time-dependent increase in TLR9 localized primarily to myofibroblasts in the dermis. Conclusion: In isolated fibroblasts, TLR9 elicits fibrotic responses mediated via endogenous TGFβ. In patients with SSc, mtDNA and other damage-associated TLR9 ligands in the skin might trigger localized activation of TLR9 signaling, TGFβ production, and consequent fibroblast activation. Disrupting this fibrotic process with inhibitors targeting TLR9 or its downstream signaling pathways might therefore represent a novel approach to SSc therapy.",
author = "Feng Fang and {Goncalves Marangoni}, Roberta and Xingchun Zhou and Yang Yang and Boping Ye and Anna Shangguang and Wenjie Qin and Wenxia Wang and Swati Bhattacharyya and Jun Wei and Tourtellotte, {Warren G.} and John Varga",
year = "2016",
month = "8",
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doi = "10.1002/art.39655",
language = "English (US)",
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pages = "1989--2002",
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Fang, F, Goncalves Marangoni, R, Zhou, X, Yang, Y, Ye, B, Shangguang, A, Qin, W, Wang, W, Bhattacharyya, S, Wei, J, Tourtellotte, WG & Varga, J 2016, 'Toll-like Receptor 9 Signaling Is Augmented in Systemic Sclerosis and Elicits Transforming Growth Factor β–Dependent Fibroblast Activation', Arthritis and Rheumatology, vol. 68, no. 8, pp. 1989-2002. https://doi.org/10.1002/art.39655

Toll-like Receptor 9 Signaling Is Augmented in Systemic Sclerosis and Elicits Transforming Growth Factor β–Dependent Fibroblast Activation. / Fang, Feng; Goncalves Marangoni, Roberta; Zhou, Xingchun; Yang, Yang; Ye, Boping; Shangguang, Anna; Qin, Wenjie; Wang, Wenxia; Bhattacharyya, Swati; Wei, Jun; Tourtellotte, Warren G.; Varga, John.

In: Arthritis and Rheumatology, Vol. 68, No. 8, 01.08.2016, p. 1989-2002.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Toll-like Receptor 9 Signaling Is Augmented in Systemic Sclerosis and Elicits Transforming Growth Factor β–Dependent Fibroblast Activation

AU - Fang, Feng

AU - Goncalves Marangoni, Roberta

AU - Zhou, Xingchun

AU - Yang, Yang

AU - Ye, Boping

AU - Shangguang, Anna

AU - Qin, Wenjie

AU - Wang, Wenxia

AU - Bhattacharyya, Swati

AU - Wei, Jun

AU - Tourtellotte, Warren G.

AU - Varga, John

PY - 2016/8/1

Y1 - 2016/8/1

N2 - 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 mediated through the action of endogenous TGFβ. Mice with experimental fibrosis showed a time-dependent increase in TLR9 localized primarily to myofibroblasts in the dermis. Conclusion: In isolated fibroblasts, TLR9 elicits fibrotic responses mediated via endogenous TGFβ. In patients with SSc, mtDNA and other damage-associated TLR9 ligands in the skin might trigger localized activation of TLR9 signaling, TGFβ production, and consequent fibroblast activation. Disrupting this fibrotic process with inhibitors targeting TLR9 or its downstream signaling pathways might therefore represent a novel approach to SSc therapy.

AB - 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 mediated through the action of endogenous TGFβ. Mice with experimental fibrosis showed a time-dependent increase in TLR9 localized primarily to myofibroblasts in the dermis. Conclusion: In isolated fibroblasts, TLR9 elicits fibrotic responses mediated via endogenous TGFβ. In patients with SSc, mtDNA and other damage-associated TLR9 ligands in the skin might trigger localized activation of TLR9 signaling, TGFβ production, and consequent fibroblast activation. Disrupting this fibrotic process with inhibitors targeting TLR9 or its downstream signaling pathways might therefore represent a novel approach to SSc therapy.

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