Composition of TWIST1 dimers regulates fibroblast activation and tissue fibrosis.

Objectives: TWIST1 is a member of the class B of basic helix-loop-helix transcription factors that regulates cell lineage determination and differentiation and has been implicated in epithelial-to-mesenchymal transition. Here, we aimed to investigate the role of TWIST1 for the activation of resident fibroblasts in systemic sclerosis (SSc).

Methods: The expression of Twist1 in fibroblasts was modulated by forced overexpression or siRNA-mediated knockdown.

Interleukin-35 is upregulated in systemic sclerosis and its serum levels are associated with early disease.

Objectives: IL-35 is a member of the IL-12 family consisting of p35/IL-12a and EBI3/IL-27b subunits. IL-35 exerts immunomodulatory activities in experimental and human autoimmune inflammatory conditions. Our aim was to assess IL-35 expression in the skin and circulation of SSc patients and to characterize its potential association with SSc-related features.

Tribbles homologue 3 stimulates canonical TGF-β signalling to regulate fibroblast activation and tissue fibrosis.

Objectives: Tribbles homologue 3 (TRB3) is a pseudokinase that modifies the activation of various intracellular signalling pathways to control fundamental processes extending from mitosis and cell activation to apoptosis and modulation of gene expression. Here, we aimed to analyse the role of TRB3 in fibroblast activation in systemic sclerosis (SSc).

Methods: The expression of TRB3 was quantified by quantitative PCR, western blot and immunohistochemistry.

Activating transcription factor 3 regulates canonical TGFβ signalling in systemic sclerosis.

Background: Activating transcription factor 3 (ATF3), a member of the ATF/cAMP-responsive element binding (CREB) family of transcription factors, regulates cellular response to stress including oxidative stress. The aim of this study was to analyse the role of ATF3 in fibroblast activation in systemic sclerosis (SSc).

Methods: ATF3 was analysed by reverse transcription quantitative PCR, western blot and immunohistochemistry.

Orphan nuclear receptor NR4A1 regulates transforming growth factor-β signaling and fibrosis.

Mesenchymal responses are an essential aspect of tissue repair. Failure to terminate this repair process correctly, however, results in fibrosis and organ dysfunction. Therapies that block fibrosis and restore tissue homeostasis are not yet available for clinical use.

Cardiomyopathy in murine models of systemic sclerosis.

Objective: Cardiomyopathy has emerged as a leading cause of death in patients with systemic sclerosis (SSc). However, the pathogenesis of SSc-related cardiomyopathy is poorly understood, and new therapies as well as platforms for testing are needed. The aim of this study was to characterize the histopathologic features of cardiomyopathy in patients with SSc and in common mouse models of SSc.

Sirt1 regulates canonical TGF-β signalling to control fibroblast activation and tissue fibrosis.

Background: Sirt1 is a member of the sirtuin family of proteins. Sirt1 is a class III histone deacetylase with important regulatory roles in transcription, cellular differentiation, proliferation and metabolism. As aberrant epigenetic modifications have been linked to the pathogenesis of systemic sclerosis (SSc), we aimed to investigate the role of Sirt1 in fibroblast activation.

The nuclear receptor constitutive androstane receptor/NR1I3 enhances the profibrotic effects of transforming growth factor β and contributes to the development of experimental dermal fibrosis.

Objective: Nuclear receptors regulate cell growth, differentiation, and homeostasis. Selective nuclear receptors promote fibroblast activation, which leads to tissue fibrosis, the hallmark of systemic sclerosis (SSc). This study was undertaken to investigate the effects of constitutive androstane receptor (CAR)/NR1I3, an orphan nuclear receptor, on fibroblast activation and experimental dermal fibrosis.

S100A4 amplifies TGF-β-induced fibroblast activation in systemic sclerosis.

Objectives: S100A4 is a calcium binding protein with regulatory functions in cell homeostasis, proliferation and differentiation that has been shown to promote cancer progression and metastasis. In the present study, we evaluated the role of S100A4 in fibroblast activation in systemic sclerosis (SSc).

Methods: The expression of S100A4 was analysed in human samples, murine models of SSc and in cultured fibroblasts by real-time PCR, immunohistochemistry and western blot.

Activation of liver X receptors inhibits experimental fibrosis by interfering with interleukin-6 release from macrophages.

Objectives: To investigate the role of liver X receptors (LXRs) in experimental skin fibrosis and evaluate their potential as novel antifibrotic targets.

Methods: We studied the role of LXRs in bleomycin-induced skin fibrosis, in the model of sclerodermatous graft-versus-host disease (sclGvHD) and in tight skin-1 (Tsk-1) mice, reflecting different subtypes of fibrotic disease. We examined both LXR isoforms using LXRα-, LXRβ- and LXR-α/β-double-knockout mice.

Stimulation of the soluble guanylate cyclase (sGC) inhibits fibrosis by blocking non-canonical TGFβ signalling.

Objectives: We have previously described the antifibrotic role of the soluble guanylate cyclase (sGC). The mode of action, however, remained elusive. In the present study, we describe a novel link between sGC signalling and transforming growth factor β (TGFβ) signalling that mediates the antifibrotic effects of the sGC.

Vitamin D receptor regulates TGF-β signalling in systemic sclerosis.

Background: Vitamin D receptor (VDR) is a member of the nuclear receptor superfamily. Its ligand, 1,25-(OH)2D, is a metabolically active hormone derived from vitamin D3. The levels of vitamin D3 are decreased in patients with systemic sclerosis (SSc).

Inhibition of casein kinase II reduces TGFβ induced fibroblast activation and ameliorates experimental fibrosis.

Objectives: Casein kinase II (CK2) is a constitutively active serine/threonine protein kinase that plays a key role in cellular transformation and tumorigenesis. The purpose of the study was to characterise whether CK2 contributes to the pathologic activation of fibroblasts in patients with SSc and to evaluate the antifibrotic potential of CK2 inhibition.

Methods: Activation of CK2, JAK2 and STAT3 in human skin and in experimental fibrosis was analysed by immunohistochemistry.

The Wnt antagonists DKK1 and SFRP1 are downregulated by promoter hypermethylation in systemic sclerosis.

Objectives: Activated Wnt signalling with decreased expression of endogenous inhibitors has recently been characterised as a central pathomechanism in systemic sclerosis (SSc). Aberrant epigenetic modifications also contribute to the persistent activation of SSc fibroblasts. We investigated whether increased Wnt signalling and epigenetic changes in SSc are causally linked via promoter hypermethylation-induced silencing of Wnt antagonists.

Heat shock protein 90 (Hsp90) inhibition targets canonical TGF-β signalling to prevent fibrosis.

Objectives: Targeted therapies for systemic sclerosis (SSc) and other fibrotic diseases are not yet available. We evaluated the efficacy of heat shock protein 90 (Hsp90) inhibition as a novel approach to inhibition of aberrant transforming growth factor (TGF)-β signalling and for the treatment of fibrosis in preclinical models of SSc.

Methods: Expression of Hsp90 was quantified by quantitative PCR, western blot and immunohistochemistry.

Combined inhibition of c-Abl and PDGF receptors for prevention and treatment of murine sclerodermatous chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGvHD) is a common complication of allogeneic bone marrow transplantation, and has a major effect on the long-term prognosis. The molecular mechanisms underlying cGvHD have been only partially revealed, and molecular targeted therapies have not yet been established for clinical use. We examined the effects of the combined inhibition of the Abelson kinase (c-Abl) and platelet-derived growth factor receptors (PDGFR) in experimental sclerodermatous cGvHD.

Inhibition of hedgehog signaling for the treatment of murine sclerodermatous chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is a prognosis limiting complication of allogeneic stem cell transplantation. The molecular mechanisms underlying cGVHD are incompletely understood, and targeted therapies are not yet established for clinical use. Here we examined the role of the hedgehog pathway in sclerodermatous cGVHD.

Inhibition of H3K27 histone trimethylation activates fibroblasts and induces fibrosis.

Objectives: Epigenetic modifications such as DNA methylation and histone acetylation have been implicated in the pathogenesis of systemic sclerosis. However, histone methylation has not been investigated so far. We therefore aimed to evaluate the role of the trimethylation of histone H3 on lysine 27 (H3K27me3) on fibroblast activation and fibrosis.

Inactivation of fatty acid amide hydrolase exacerbates experimental fibrosis by enhanced endocannabinoid-mediated activation of CB1.

Background: Selective targeting of the cannabinoid receptors CB1 and CB2 by synthetic compounds has revealed opposing roles of both receptors in fibrosis.

Objectives: To characterise the role of endogenous cannabinoids (endocannabinoids) and their predominant receptor in fibrosis.

Methods: The levels of endocannabinoids in mice were modulated by pharmacological or genetic inactivation of the enzyme fatty acid amide hydrolase (FAAH).

Pomalidomide is effective for prevention and treatment of experimental skin fibrosis.

Objectives: Tissue fibrosis is a major hallmark and a leading cause of death in systemic sclerosis (SSc). Here, we investigated the antifibrotic effects of pomalidomide, an analogue of thalidomide with potent immunomodulatory effects, in preclinical models of skin fibrosis.

Methods: We evaluated the antifibrotic effects of pomalidomide in preventive as well as therapeutic treatment regimes using bleomycin-induced dermal fibrosis as a model of early, inflammatory stages of fibrosis and the tight-skin mouse model as a model of later stages of fibrosis with endogenous activation of fibroblasts.

JAK-2 as a novel mediator of the profibrotic effects of transforming growth factor β in systemic sclerosis.

Objective: To investigate whether JAK-2 contributes to the pathologic activation of fibroblasts in patients with systemic sclerosis (SSc) and to evaluate the antifibrotic potential of JAK-2 inhibition for the treatment of SSc.

Methods: Activation of JAK-2 in human skin and in experimental fibrosis was determined by immunohistochemical analysis. JAK-2 signaling was inhibited by the selective JAK-2 inhibitor TG101209 or by small interfering RNA.

Activation of canonical Wnt signalling is required for TGF-β-mediated fibrosis.

The transforming growth factor-β (TGF-β) signalling pathway is a key mediator of fibroblast activation that drives the aberrant synthesis of extracellular matrix in fibrotic diseases. Here we demonstrate a novel link between transforming growth factor-β and the canonical Wnt pathway. TGF-β stimulates canonical Wnt signalling in a p38-dependent manner by decreasing the expression of the Wnt antagonist Dickkopf-1.

Inhibition of hedgehog signalling prevents experimental fibrosis and induces regression of established fibrosis.

Objectives: Tissue fibrosis is a leading cause of death in patients with systemic sclerosis (SSc). Effective antifibrotic treatments are not available. Here, the authors investigated inhibition of hedgehog signalling by targeting Smoothened (Smo) as a novel antifibrotic approach.

Hedgehog signaling controls fibroblast activation and tissue fibrosis in systemic sclerosis.

Objective: Hedgehog signaling not only plays crucial roles during human development but also has been implicated in the pathogenesis of several diseases in adults. The aim of the present study was to investigate the role of the hedgehog pathway in fibroblast activation in systemic sclerosis (SSc).

Methods: Activation of the hedgehog pathway was analyzed by immunohistochemistry and real-time polymerase chain reaction (PCR).

The 12/15-lipoxygenase pathway counteracts fibroblast activation and experimental fibrosis.

Background: Idiopathic and inflammation-dependent fibrotic diseases such systemic sclerosis (SSc) impose a major burden on modern societies. Understanding endogenous mechanisms, which counteract fibrosis, may yield new therapeutic approaches. Lipoxins are highly potent lipid mediators, which have recently been found to be decreased in SSc.