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Activation of JUN in fibroblasts promotes pro-fibrotic programme and modulates protective immunity.

ABSTRACT: The transcription factor JUN is highly expressed in pulmonary fibrosis. Its induction in mice drives lung fibrosis, which is abrogated by administration of anti-CD47. Here, we use high-dimensional mass cytometry to profile protein expression and secretome of cells from patients with pulmonary fibrosis. We show that JUN is activated in fibrotic fibroblasts that expressed increased CD47 and PD-L1. Using ATAC-seq and ChIP-seq, we found that activation of JUN rendered promoters and enhancers of CD47 and PD-L1 accessible. We further detect increased IL-6 that amplified JUN-mediated CD47 enhancer activity and protein expression. Using an in vivo mouse model of fibrosis, we found two distinct mechanisms by which blocking IL-6, CD47 and PD-L1 reversed fibrosis, by increasing phagocytosis of profibrotic fibroblasts and by eliminating suppressive effects on adaptive immunity. Our results identify specific immune mechanisms that promote fibrosis and suggest a therapeutic approach that could be used alongside conventional anti-fibrotics for pulmonary fibrosis.

SUBMITTER: Cui L

PROVIDER: S-EPMC7270081 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Activation of JUN in fibroblasts promotes pro-fibrotic programme and modulates protective immunity.

Cui Lu L Chen Shih-Yu SY Lerbs Tristan T Lee Jin-Wook JW Domizi Pablo P Gordon Sydney S Kim Yong-Hun YH Nolan Garry G Betancur Paola P Wernig Gerlinde G

Nature communications 20200603 1

The transcription factor JUN is highly expressed in pulmonary fibrosis. Its induction in mice drives lung fibrosis, which is abrogated by administration of anti-CD47. Here, we use high-dimensional mass cytometry to profile protein expression and secretome of cells from patients with pulmonary fibrosis. We show that JUN is activated in fibrotic fibroblasts that expressed increased CD47 and PD-L1. Using ATAC-seq and ChIP-seq, we found that activation of JUN rendered promoters and enhancers of CD47 ...[more]

PMID: 32493933

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Project description:BACKGROUND:Scleroderma (systemic sclerosis; SSc) is a clinically heterogeneous and often lethal acquired disorder of the connective tissue that is characterized by vascular, immune/inflammatory and fibrotic manifestations. Tissue fibrosis is the main cause of morbidity and mortality in SSc and an unmet medical challenge, mostly because of our limited understanding of the molecular factors and signalling events that trigger and sustain disease progression. Recent evidence has correlated skin fibrosis in SSc with stabilization of proto-oncogene Ha-Ras secondary to auto-antibody stimulation of reactive oxygen species production. The goal of the present study was to explore the molecular connection between Ha-Ras stabilization and collagen I production, the main read-out of fibrogenesis, in a primary dermal fibroblast culture system that replicates the early stages of disease progression in SSc. RESULTS:Forced expression of proto-oncogene Ha-Ras in dermal fibroblasts demonstrated the promotion of an immediate collagen I up-regulation, as evidenced by enhanced activity of a collagen I-driven luciferase reporter plasmid and increased accumulation of endogenous collagen I proteins. Moreover, normal levels of Tgf? transcripts and active transforming growth factor-beta (TGF?) implied Ha-Ras stimulation of the canonical Smad2/3 signalling pathway independently of TGF? production or activation. Heightened Smad2/3 signalling was furthermore correlated with greater Smad3 phosphorylation and Smad3 protein accumulation, suggesting that Ha-Ras may target both Smad2/3 activation and turnover. Additional in vitro evidence excluded a contribution of ERK1/2 signalling to improper Smad3 activity and collagen I production in cells that constitutively express Ha-Ras. CONCLUSIONS:Our study shows for the first time that constitutively elevated Ha-Ras protein levels can directly stimulate Smad2/3 signalling and collagen I accumulation independently of TGF? neo-synthesis and activation. This finding therefore implicates the Ha-Ras pathway with the early onset of fibrosis in SSc and implicitly identifies new therapeutic targets in SSc.

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Activation of JUN in fibroblasts promotes pro-fibrotic programme and modulates protective immunity.

Publications

Activation of JUN in fibroblasts promotes pro-fibrotic programme and modulates protective immunity.

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