Bleomycin-induced Dermal Fibrosis Research Articles

SAT0032 The synthetic cannabinoid ajulemic acid exerts potent anti-fibrotic effects in experimental models of systemic sclerosis

BackgroundCannabinoids are able to modulate fibrogenesis in scleroderma. Ajulemic acid (AjA) is a non-psychoactive synthetic analogue of tetrahydrocannabinol (THC), able to bind the peroxisome proliferator-activated receptor-γ (PPAR-γ) (1). Recent evidence...

SAT0026 Combined inhibition of notch, hedgehog and wnt signaling exerts additive anti-fibrotic effects and reduces toxicity

BackgroundRecent studies demonstrated that the morphogenic pathways Notch, hedgehog (Hh) and Wnt are activated in systemic sclerosis and that inhibition of these morphogen pathways exerted potent anti-fibrotic effects in different...

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

ObjectivesTargeted 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...

Blockade of canonical Wnt signalling ameliorates experimental dermal fibrosis

Background and objectivesFibrosis is a major socioeconomic burden, but effective antifibrotic therapies are not available in the clinical routine. There is growing evidence for a central role of Wnt signalling...

Performance of Skin Ultrasound to Measure Skin Involvement in Different Animal Models of Systemic Sclerosis

Animal models are widely used in systemic sclerosis (SSc) research. We set out to determine whether ultrasonography (US) could be used to assess skin fibrosis in two complementary SSc-models: the bleomycin-induced dermal fibrosis model and the tight-skin 1 mouse model. Back skin thickness was measured using a high-frequency ultrasound dedicated to the small animal. There was no significant difference in dermal thickness measured by US between mice injected with bleomycin and those treated with NaCl. These results were inconsistent with histological analyses. Mean US hypodermal thickness was significantly higher in tight-skin 1 mice as compared with Pa/Pa control subgroup (p = 0.02). Histologic and US measures of dermal and hypodermal thicknesses in this model were well correlated (r = 0.79). The intra-observer concordance was 0.96 for hypodermal thickness. US is reliable and sensitive in detecting hypodermal thickening in the tight-skin 1 mouse model. Further larger studies are warranted to better determine the place of US in SSc-research.

Activation of pregnane X receptor inhibits experimental dermal fibrosis

ObjectiveTo assess the antifibrotic effects of pregnane X receptors (PXRs) in experimental dermal fibrosis.MethodsThe antifibrotic effects of PXR activation by 5-pregnen-3β-ol-20-one-16α-carbonitrile (PCN) were studied in the bleomycin model for prevention...

Critical role of the adhesion receptor DNAX accessory molecule-1 (DNAM-1) in the development of inflammation-driven dermal fibrosis in a mouse model of systemic sclerosis

ObjectiveTo investigate the contribution of the adhesion receptor DNAX accessory molecule-1 (DNAM-1) in the development of dermal fibrosis on gene inactivation and targeted molecular strategies.MethodsHuman skin expression of DNAM-1 was...

Inactivation of tankyrases reduces experimental fibrosis by inhibiting canonical Wnt signalling

ObjectivesCanonical Wnt signalling has recently emerged as a key mediator of fibroblast activation and tissue fibrosis in systemic sclerosis. Here, we investigated tankyrases as novel molecular targets for inhibition of...

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

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. 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. Bleomycin-induced dermal fibrosis in mice and TSK-1 mice were used to evaluate the antifibrotic potential of specific JAK-2 inhibition in vivo. Increased activation of JAK-2 was detected in the skin of patients with SSc, particularly in fibroblasts. The activation of JAK-2 was dependent on transforming growth factor β (TGFβ) and persisted in cultured SSc fibroblasts. Inhibition of JAK-2 reduced basal collagen synthesis selectively in SSc fibroblasts but not in resting healthy dermal fibroblasts. Moreover, inhibition of JAK-2 prevented the stimulatory effects of TGFβ on fibroblasts. Treatment with TG101209 not only prevented bleomycin-induced fibrosis but also effectively reduced skin fibrosis in TSK-1 mice. We demonstrated that JAK-2 is activated in a TGFβ-dependent manner in SSc. Considering the potent antifibrotic effects of JAK-2 inhibition, our study might have direct translational implications, because inhibitors of JAK-2 are currently being evaluated in clinical trials for myeloproliferative disorders and would also be available for evaluation in patients with SSc.

Pomalidomide is effective for prevention and treatment of experimental skin fibrosis

ObjectivesTissue 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...

Inhibition of sumoylation prevents experimental fibrosis

ObjectivesFibrosis is a predominant cause of death in systemic sclerosis (SSc). First epigenetic modifications have recently been shown to contribute to activation of SSc fibroblasts. Here, we investigated inhibition of...

Synthetic cannabinoid ajulemic acid exerts potent antifibrotic effects in experimental models of systemic sclerosis

BackgroundCannabinoids modulate fibrogenesis in scleroderma. Ajulemic acid (AjA) is a non-psychoactive synthetic analogue of tetrahydrocannabinol that can bind the peroxisome proliferator-activated receptor-γ (PPAR-γ). Recent evidence suggests a key role for...

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

ObjectivesTissue 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...

Stimulation of soluble guanylate cyclase reduces experimental dermal fibrosis

BackgroundFibrosis and vascular disease are cardinal features of systemic sclerosis (SSc). Stimulators of soluble guanylate cyclase (sGC) are vasoactive drugs that are currently being evaluated in phase III clinical trials...

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

BackgroundIdiopathic 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...

Jun N-terminal kinase as a potential molecular target for prevention and treatment of dermal fibrosis

ObjectivesThe hallmark of systemic sclerosis (SSc) is the accumulation of extracellular matrix proteins by pathologically activated fibroblasts. This study analysed the antifibrotic effects of the selective c-Jun N-terminal kinase (JNK)...

Targeting STAT4 in systemic sclerosis: a promising new direction

Evaluation of: Avouac J, Fürnrohr BG, Tomcik M et al. Inactivation of the transcription factor STAT-4 prevents inflammation-driven fibrosis in animal models of systemic sclerosis. Arthritis Rheum. 63(3), 800–809 (2011).STAT4 has been identified as a genetic risk factor for the development of autoimmune diseases including systemic sclerosis. STAT4 regulates Th1 cell development and cell-mediated immunity, but it is not known how it may regulate the development of dermal fibrosis. Using the bleomycin-induced dermal fibrosis model, it has now been demonstrated that STAT4-deficient mice have reduced dermal fibrosis in part via STAT4-dependent alterations in T-cell proliferation and cytokine production. These data stress the importance of STAT4 in autoimmune diseases such as systemic sclerosis and provide an important direction for future research to improve our understanding of systemic sclerosis pathogenesis.

Inhibition of Notch signaling prevents experimental fibrosis and induces regression of established fibrosis

Tissue fibrosis caused by pathologic activation of fibroblasts with increased synthesis of extracellular matrix components is a major hallmark of systemic sclerosis (SSc). Notch signaling regulates tissue differentiation, and abnormal activation of Notch signaling has been implicated in the pathogenesis of various malignancies. The present study was undertaken to investigate the role of Notch signaling in SSc and to evaluate the therapeutic potential of Notch inhibition for the treatment of fibrosis. Activation of the Notch pathways was analyzed by staining for the Notch intracellular domain (NICD) and quantification of levels of HES-1 messenger RNA. In the mouse model of bleomycin-induced dermal fibrosis and in tight skin 1 mice, Notch signaling was inhibited by the γ-secretase inhibitor DAPT and by overexpression of a Notch-1 antisense construct. Notch signaling was activated in SSc in vivo, with accumulation of the NICD and increased transcription of the target gene HES-1. Overexpression of a Notch antisense construct prevented bleomycin-induced fibrosis and hypodermal thickening in tight skin 1 mice. Potent antifibrotic effects were also obtained with DAPT treatment. In addition to prevention of fibrosis, targeting of Notch signaling resulted in almost complete regression of established experimental fibrosis. The present results demonstrate that pharmacologic as well as genetic inhibition of Notch signaling exerts potent antifibrotic effects in different murine models of SSc. These findings might have direct translational implications because different inhibitors of the γ-secretase complex are available and have yielded promising results in cancer trials.

Amelioration of dermal fibrosis by genetic deletion or pharmacologic antagonism of lysophosphatidic acid receptor 1 in a mouse model of scleroderma

Scleroderma (systemic sclerosis [SSc]), is characterized by progressive multiorgan fibrosis. We recently implicated lysophosphatidic acid (LPA) in the pathogenesis of pulmonary fibrosis. The purpose of the present study was to investigate the roles of LPA and two of its receptors, LPA₁ and LPA₂, in dermal fibrosis in a mouse model of SSc. Wild type (WT), and LPA₁-knockout (KO) and LPA₂-KO mice were injected subcutaneously with bleomycin or phosphate buffered saline (PBS) once daily for 28 days. Dermal thickness, collagen content, and numbers of cells positive for α-smooth muscle actin (α-SMA) or phospho-Smad2 were determined in bleomycin-injected and PBS-injected skin. In separate experiments, a novel selective LPA₁ antagonist AM095 or vehicle alone was administered by oral gavage to C57BL/6 mice that were challenged with 28 daily injections of bleomycin or PBS. AM095 or vehicle treatments were initiated concurrently with, or 7 or 14 days after, the initiation of bleomycin and PBS injections and continued to the end of the experiments. Dermal thickness and collagen content were determined in injected skin. The LPA₁ -KO mice were markedly resistant to bleomycin-induced increases in dermal thickness and collagen content, whereas the LPA₂-KO mice were as susceptible as the WT mice. Bleomycin-induced increases in dermal α-SMA+ and phospho-Smad2+ cells were abrogated in LPA₁-KO mice. Pharmacologic antagonism of LPA₁ with AM095 significantly attenuated bleomycin-induced dermal fibrosis when administered according to either a preventive regimen or two therapeutic regimens. These results suggest that LPA/LPA₁ pathway inhibition has the potential to be an effective new therapeutic strategy for SSc, and that LPA₁ is an attractive pharmacologic target in dermal fibrosis.

The transcription factor JunD mediates transforming growth factor β-induced fibroblast activation and fibrosis in systemic sclerosis

ObjectivesTransforming growth factor β (TGFβ) has been identified as a key player in fibrotic diseases. However, the molecular mechanisms by which TGFβ activates fibroblasts are incompletely understood. Here, the role...