Attenuation of fibroblast activation and fibrosis by adropin in systemic sclerosis.

Fibrotic diseases impose a major socioeconomic challenge on modern societies and have limited treatment options. Adropin, a peptide hormone encoded by the energy homeostasis-associated (ENHO) gene, is implicated in metabolism and vascular homeostasis, but its role in the pathogenesis of fibrosis remains enigmatic. Here, we used machine learning approaches in combination with functional in vitro and in vivo experiments to characterize adropin as a potential regulator involved in fibroblast activation and tissue fibrosis in systemic sclerosis (SSc). We demonstrated consistent down-regulation of adropin/ENHO in skin across multiple cohorts of patients with SSc. The prototypical profibrotic cytokine TGFß reduced adropin/ENHO expression in a JNK-dependent manner. Restoration of adropin signaling by therapeutic application of bioactive adropin34-76 peptides in turn inhibited TGFß-induced fibroblast activation and fibrotic tissue remodeling in primary human dermal fibroblasts, three-dimensional full-thickness skin equivalents, mouse models of bleomycin-induced pulmonary fibrosis and sclerodermatous chronic graft-versus-host-disease (sclGvHD), and precision-cut human skin slices. Knockdown of GPR19, an adropin receptor, abrogated the antifibrotic effects of adropin in fibroblasts. RNA-seq demonstrated that the antifibrotic effects of adropin34-76 were functionally linked to deactivation of GLI1-dependent profibrotic transcriptional networks, which was experimentally confirmed in vitro, in vivo, and ex vivo using cultured human dermal fibroblasts, a sclGvHD mouse model, and precision-cut human skin slices. ChIP-seq confirmed adropin34-76-induced changes in TGFß/GLI1 signaling. Our study characterizes the TGFß-induced down-regulation of adropin/ENHO expression as a potential pathomechanism of SSc as a prototypical systemic fibrotic disease that unleashes uncontrolled activation of profibrotic GLI1 signaling.

Endothelial Response to Type I Interferon Contributes to Vasculopathy and Fibrosis and Predicts Disease Progression of Systemic Sclerosis.

OBJECTIVE: Interferon (IFN)-1 signatures are a hallmark of patients with systemic sclerosis (SSc). However, its significance in clinical stratification and contribution to deterioration still need to be better understood. METHODS: For hypothesis generation, we performed single-cell RNA sequencing (scRNA-seq) on skin biopsies (four patients with SSc and two controls) using the BD Rhapsody platform. Two publicly available data sets of skin scRNA-seq were used for validation (GSE138669: 12 patients with diffuse cutaneous SSc [dcSSc] and 10 controls; GSE195452: 52 patients with dcSSc and 41 patients with limited cutaneous SSc [lcSSc] and 54 controls). The IFN-1 signature was mapped, functionally investigated in a bleomycin plus IFNα-2 adenovirus-associated virus (AAV)-induced model and verified in an SSc cohort (n = 61). RESULTS: The discovery and validation data sets showed similar findings. Endothelial cells (ECs) had the most prominent IFN-1 signature among dermal nonimmune cells. The EC IFN-1 signature was increased both in patients with SSc versus controls and in patients with dcSSc versus those with lcSSc. Among EC subclusters, the IFN-1 signature was statistically higher in the capillary ECs of patients with dcSSc, which was higher than those in patients with lcSSc, which in turn was higher than those in healthy controls (HCs). Endothelial-to-mesenchymal transition (EndoMT) scores increased in parallel. Deteriorated bleomycin-induced dermal fibrosis, EndoMT, and perivascular fibrosis and caused blood vessel loss with EC apoptosis. Vascular myxovirus resistance (MX) 1, an IFN-1 response protein, was significantly increased both in total SSc versus HC skin and in dcSSc versus lcSSc skin. Baseline vascular MX1 performed similarly to skin score in predicting disease progression over 6 to 34 months in total SSc and was superior in the dcSSc subpopulation. CONCLUSION: The EC IFN-1 signature distinguished SSc skin subtypes and disease progression and may contribute to vasculopathy and fibrosis.

Iguratimod attenuated fibrosis in systemic sclerosis via targeting early growth response 1 expression.

BACKGROUND: The early growth response 1 (EGR1) is a central transcription factor involved in systemic sclerosis (SSc) pathogenesis. Iguratimod is a synthesized anti-rheumatic disease-modifying drug, which shows drastic inhibition to EGR1 expression in B cells. This study is aiming to investigate the anti-fibrotic effect of iguratimod in SSc. METHODS: EGR1 was detected by immunofluorescence staining real-time PCR or western blot. Iguratimod was applied in EGR1 overexpressed or knockdown human dermal fibroblast, bleomycin pre-treated mice, tight skin 1 mice, and SSc skin xenografts. RNA sequencing was performed in cultured fibroblast and xenografts to identify the iguratimod regulated genes. RESULTS: EGR1 overexpressed predominantly in non-immune cells of SSc patients. Iguratimod reduced EGR1 expression in fibroblasts and neutralized changes of EGR1 response genes regulated by TGFß. The extracellular matrix (ECM) production and activation of fibroblasts were attenuated by iguratimod while EGR1 overexpression reversed this effect of iguratimod. Iguratimod ameliorated the skin fibrosis induced by bleomycin and hypodermal fibrosis in TSK-1 mice. Decreasing in the collagen content as well as the density of EGR1 or TGFß positive fibroblasts of skin xenografts from naïve SSc patients was observed after local treatment of iguratimod. CONCLUSION: Targeting EGR1 expression is a probable underlying mechanism for the anti-fibrotic effect of iguratimod.

TGFß promotes fibrosis by MYST1-dependent epigenetic regulation of autophagy.

Activation of fibroblasts is essential for physiological tissue repair. Uncontrolled activation of fibroblasts, however, may lead to tissue fibrosis with organ dysfunction. Although several pathways capable of promoting fibroblast activation and tissue repair have been identified, their interplay in the context of chronic fibrotic diseases remains incompletely understood. Here, we provide evidence that transforming growth factor-ß (TGFß) activates autophagy by an epigenetic mechanism to amplify its profibrotic effects. TGFß induces autophagy in fibrotic diseases by SMAD3-dependent downregulation of the H4K16 histone acetyltransferase MYST1, which regulates the expression of core components of the autophagy machinery such as ATG7 and BECLIN1. Activation of autophagy in fibroblasts promotes collagen release and is both, sufficient and required, to induce tissue fibrosis. Forced expression of MYST1 abrogates the stimulatory effects of TGFß on autophagy and re-establishes the epigenetic control of autophagy in fibrotic conditions. Interference with the aberrant activation of autophagy inhibits TGFß-induced fibroblast activation and ameliorates experimental dermal and pulmonary fibrosis. These findings link uncontrolled TGFß signaling to aberrant autophagy and deregulated epigenetics in fibrotic diseases and may contribute to the development of therapeutic interventions in fibrotic diseases.

Targeting of canonical WNT signaling ameliorates experimental sclerodermatous chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is a major life-threatening complication of allogeneic hematopoietic stem cell transplantation. The molecular mechanisms underlying cGVHD remain poorly understood, and targeted therapies for clinical use are not well established. Here, we examined the role of the canonical WNT pathway in sclerodermatous cGVHD (sclGVHD). WNT signaling was activated in human sclGVHD with increased nuclear accumulation of the transcription factor ß-catenin and a WNT-biased gene expression signature in lesional skin. Treatment with the highly selective tankryase inhibitor G007-LK, the CK1α agonist pyrvinium, or the LRP6 inhibitor salinomycin abrogated the activation of WNT signaling and protected against experimental cGVHD, without a significant impact on graft-versus-leukemia effect (GVL). Treatment with G007-LK, pyrvinium, or salinomycin almost completely prevented the development of clinical and histological features in the B10.D2 (H-2d) → BALB/c (H-2d) and LP/J (H-2b) → C57BL/6 (H-2b) models of sclGVHD. Inhibition of canonical WNT signaling reduced the release of extracellular matrix from fibroblasts and reduced leukocyte influx, suggesting that WNT signaling stimulates fibrotic tissue remodeling by direct effects on fibroblasts and by indirect inflammation-dependent effects in sclGVHD. Our findings may have direct translational potential, because pyrvinium is in clinical use, and tankyrase inhibitors are in clinical trials for other indications.

Efficacy of Combination Therapy With Pirfenidone and Low-Dose Cyclophosphamide for Refractory Interstitial Lung Disease Associated With Connective Tissue Disease: A Case-Series of Seven Patients.

OBJECTIVES: This study reports a low dose combination therapy of cyclophosphamide (CYC) and pirfenidone (PFD) and the efficiency and safety of the therapy in refractory connective tissue disease associated interstitial lung disease (CTD-ILD) patients. PATIENTS AND METHODS: The study included seven CTD-ILD patients (2 males, 5 females; mean age 48.8 years; range, 32 to 63 years) treated between January 2016 and December 2017 in our clinic. At enrolment, all patients had shown no improvement in their symptoms (dyspnea or cough) after at least one month of high dose steroids treatment. Patients who had received adjusted immunosuppressive agents other than steroids or anti-fibrotic medications within the three months before enrolment were excluded. We changed the treatment to a low dose combination of CYC 0.4 g/m2 monthly and PFD 300 mg twice per day and quickly reduced the steroids. All the patients were followed-up for 12 months. RESULTS: Two patients had anti-synthetase syndrome, two had Sjögren syndrome, two had scleroderma and one had mixed connective tissue disease. The baseline forced vital capacity (FVC) was 39-81% and the six-minute walk distance (6MWD) was 202 m-324 m. Within 12 months follow-up, the median improvement in the FVC was 13.4% (range, 0-35.9%), the median improvement of carbon monoxide diffusing capacity was 6.3% (range, 1.7-16%) and the median improvement of 6MWD was 52.7% (range, 34.4-86.3%). All the patients were self-sufficient, and their dyspnea, chest high- resolution computed tomography scores, and quality of life improved simultaneously. Exceeding our expectations, no adverse events associated with CYC or PFD were observed during the follow-up period. CONCLUSION: Our study provided preliminary while promising clinical evidence for combination therapy of CYC-PFD for CTD-ILD. A low dose combination of CYC and PFD was unexpectedly well tolerated, with satisfactory effects in refractory CTD-ILD patients. Well-designed controlled studies are needed to further establish the safety and efficacy of this approach.

PGC-1α regulates autophagy to promote fibroblast activation and tissue fibrosis.

OBJECTIVES: Coactivators are a heterogeneous family of transcriptional regulators that are essential for modulation of transcriptional outcomes and fine-tune numerous cellular processes. The aim of the present study was to evaluate the role of the coactivator peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in the pathogenesis of systemic sclerosis (SSc). METHODS: Expression of PGC-1α was analysed by real-time PCR, western blot and immunofluorescence. Modulation of autophagy was analysed by reporter studies by expression of autophagy-related genes. The effects of PGC-1α knockdown on collagen production and myofibroblast differentiation were analysed in cultured human fibroblasts and in two mouse models with fibroblast-specific knockout of PGC-1α. RESULTS: The expression of PGC-1α was induced in dermal fibroblasts of patients with SSc and experimental murine fibrosis. Transforming growth factor beta (TGFß), hypoxia and epigenetic mechanisms regulate the expression of PGC-1α in fibroblasts. Knockdown of PGC-1α prevented the activation of autophagy by TGFß and this translated into reduced fibroblast-to-myofibroblast differentiation and collagen release. Knockout of PGC-1α in fibroblasts prevented skin fibrosis induced by bleomycin and by overexpression of a constitutively active TGFß receptor type I. Moreover, pharmacological inhibition of PGC-1α by SR18292 induced regression of pre-established, bleomycin-induced skin fibrosis. CONCLUSION: PGC-1α is upregulated in SSc and promotes autophagy to foster TGFß-induced fibroblast activation. Targeting of PGC-1α prevents aberrant autophagy, inhibits fibroblast activation and tissue fibrosis and may over therapeutic potential.