Fibroblast abnormalities in the pathogenesis of systemic sclerosis

Anti-fibrotic effect of a selective estrogen receptor modulator in systemic sclerosis

Background

The rarity of systemic sclerosis (SSc) has hampered the development of therapies for this intractable autoimmune disease. Induced pluripotent stem cell (iPSC) can be differentiated into the key disease-affected cells in vitro. The generation of patient-derived iPSCs has opened up possibilities for rare disease modeling. Since these cells can recapitulate the disease phenotypes of the cell in question, they are useful high-throughput platforms for screening for drugs that can reverse these abnormal phenotypes.

Methods

SSc iPSC was generated from PBMC by Sendai virus. Human iPSC lines from SSc patients were differentiated into dermal fibroblasts and keratinocytes. The iPSC-derived differentiated cells from the SSc patients were used on high-throughput platforms to screen for FDA-approved drugs that could be effective treatments for SSc.

Results

Skin organoids were generated from these cells exhibited fibrosis that resembled SSc skin. Screening of the 770-FDA-approved drug library showed that the anti-osteoporotic drug raloxifene reduced SSc iPSC-derived fibroblast proliferation and extracellular matrix production and skin fibrosis in organoids and bleomycin-induced SSc-model mice.

Conclusions

This study reveals that a disease model of systemic sclerosis generated using iPSCs-derived skin organoid is a novel tool for in vitro and in vivo dermatologic research. Since raloxifene and bazedoxifene are well-tolerated anti-osteoporotic drugs, our findings suggest that selective estrogen receptor modulator (SERM)-class drugs could treat SSc fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02987-w.

JAK1/2 Inhibitor Baricitinib Improves Skin Fibrosis and Digital Ulcers in Systemic Sclerosis

Background

Systemic sclerosis (SSc) is a rare disabling connective tissue disease with few available treatment options. Diffuse cutaneous systemic sclerosis (dcSSc) is associated with high mortality. A previous experiment has shown that JAK2 inhibitor can significantly improve skin fibrosis in bleomycin (BLM)-induced murine model, including reducing dermal thickening and collagen accumulation. We aimed to describe the efficacy of oral JAK1/2 inhibitor baricitinib in SSc patients, especially focusing on skin fibrosis and microvascular manifestations.

Methods

We described the different effects of oral selective JAK1, JAK2, or JAK3 inhibitor treatment in a BLM-induced skin fibrosis mouse model. Furthermore, 10 adult patients with dcSSc were treated with baricitinib. We assessed the changes in modified rodman skin score (mRSS) and digital ulcer net burden at week 12 and 24 from baseline. We also compared the absolute changes in scores on the Scleroderma Health Assessment Questionnaire (SHAQ) and a total score on the St. George's Respiratory Questionnaire (SGRQ) over a 24-week period.

Results

In the experimental mouse model of skin fibrosis, a JAK1 and JAK2 inhibitor ameliorated skin fibrosis, and a JAK2 inhibitor had the most obvious effect. Treatment with the JAK2 inhibitor also blunted the capillary rarefaction. We demonstrated that skin fibrosis and digital ulcers were significantly relieved in 10 SSc patients treated with baricitinib. The mRSS significantly improved at week 12 from baseline, with a mean change in mRSS of -8.3 [95% confidence interval (CI), -12.03 to -4.574; p = 0.0007] and improved greater at week 24 to -11.67 (95% CI, -16.84 to -6.496; p = 0.0008). Among the four patients with digital ulcers (DU), three were completely healed at week 24, the number of ulcers in another patient was significantly reduced, and there was no patient with new ulcers. Only one adverse event (AE) of herpes zoster was observed.

Conclusions

Our results indicate that selective JAK1 and JAK2 inhibitor alleviates skin fibrosis, and oral JAK1/2 inhibitor baricitinib is a potentially effective treatment for dcSSc patients with skin fibrosis and DU. Baricitinib was well-tolerated by most patients in this study. Additional large clinical trials are needed to confirm our pilot findings.

Chinese Clinical Trial Registry Number

ChiCTR2000030995.

Pharmacological inhibition of GLUT1 as a new immunotherapeutic approach after myocardial infarction

Myocardial infarction (MI) is one of the major contributors to cardiovascular morbidity and mortality. Excess inflammation significantly contributes to cardiac remodeling and heart failure after MI. Accumulating evidence has shown the central role of cellular metabolism in regulating the differentiation and function of cells. Metabolic rewiring is particularly relevant for proinflammatory responses induced by ischemia. Hypoxia reduces mitochondrial oxidative phosphorylation (OXPHOS) and induces increased reliance on glycolysis. Moreover, activation of a proinflammatory transcriptional program is associated with preferential glucose metabolism in leukocytes. An improved understanding of the mechanisms that regulate metabolic adaptations holds the potential to identify new metabolic targets and strategies to reduce ischemic cardiac damage, attenuate excess local inflammation and ultimately prevent the development of heart failure. Among possible drug targets, glucose transporter 1 (GLUT1) gained considerable interest considering its pivotal role in regulating glucose availability in activated leukocytes and the availability of small molecules that selectively inhibit it. Therefore, we summarize current evidence on the role of GLUT1 in leukocytes (focusing on macrophages and T cells) and non-leukocytes, including cardiomyocytes, endothelial cells and fibroblasts regarding ischemic heart disease. Beyond myocardial infarction, we can foresee the role of GLUT1 blockers as a possible pharmacological approach to limit pathogenic inflammation in other conditions driven by excess sterile inflammation.

Engineering Advanced In Vitro Models of Systemic Sclerosis for Drug Discovery and Development

Systemic sclerosis (SSc) is a complex multisystem disease with the highest case-specific mortality among all autoimmune rheumatic diseases, yet without any available curative therapy. Therefore, the development of novel therapeutic antifibrotic strategies that effectively decrease skin and organ fibrosis is needed. Existing animal models are cost-intensive, laborious and do not recapitulate the full spectrum of the disease and thus commonly fail to predict human efficacy. Advanced in vitro models, which closely mimic critical aspects of the pathology, have emerged as valuable platforms to investigate novel pharmaceutical therapies for the treatment of SSc. This review focuses on recent advancements in the development of SSc in vitro models, sheds light onto biological (e.g., growth factors, cytokines, coculture systems), biochemical (e.g., hypoxia, reactive oxygen species) and biophysical (e.g., stiffness, topography, dimensionality) cues that have been utilized for the in vitro recapitulation of the SSc microenvironment, and highlights future perspectives for effective drug discovery and validation.

B cells in systemic sclerosis: from pathophysiology to treatment

Systemic sclerosis is a debilitating autoimmune disease with unknown pathogenesis. The clinical phenotype of fibrosis is preceded by vascular and immunologic aberrations. Adaptive immunity has been extensively studied in patients with the disease and B cells appear to be dysregulated. This is evident in peripheral blood B cell subsets, with activated effector B cells and impaired B regulatory function. In addition, B cells infiltrate target organs and tissues of patients with the disease, such as the skin and the lung, indicating a probable role in the pathogenesis. Impaired B cell homeostasis explains the rationale behind B cell therapeutic targeting. Indeed, several studies in recent years have shown that depletion of B cells appears to be a promising treatment alongside current established therapeutic choices, such as mycophenolate. In this review, B cell aberrations in animal models and human patients with systemic sclerosis will be presented. Moreover, we will also summarize current existing data regarding therapeutic targeting of the B cells in systemic sclerosis.

[Treatment of systemic sclerosis-associated interstitial lung disease]

BACKGROUND

Systemic sclerosis (SSc) is a fibrosing autoimmune disease of the connective tissue. In addition to skin fibrosis, pulmonary involvement and interstitial lung disease (ILD) in particular are the most common and severe manifestations of SSc. The disease is associated with a substantial risk of morbidity and mortality, especially in progressive ILD. In the last 5 years new treatment concepts for SSc-ILD have been investigated in numerous clinical studies.

MATERIAL AND METHODS

This review is based on a literature search in PubMed, focusing on the most relevant papers published up to the end of 2018 with the keywords "SSc" and "treatment".

RESULTS

The treatment of SSc-ILD has changed over the last few years due to the results of many clinical studies. The updated guidelines of the European League Against Rheumatism (EULAR) recommend the use of cyclophosphamide or hematopoietic stem cell transplantation. Data for a positive influence on SSc-ILD are also available for mycophenolate, tocilizumab and anabasum. Because of the pathophysiological similarities to idiopathic pulmonary fibrosis, the use of the antifibrotic agents nintedanib and pirfenidone is currently being investigated in randomized, multicenter clinical trials and could be a novel and promising therapeutic strategy.

CONCLUSION

Current drug studies may provide innovative therapeutic perspectives for SSc-ILD and could significantly improve the prognosis of affected patients in the future.

Differentially expressed genes between systemic sclerosis and rheumatoid arthritis

Background

Evidence is accumulating to characterise the key differences between systemic sclerosis (SSc) and rheumatoid arthritis (RA), which are similar but distinct systemic autoimmune diseases. However, the differences at the genetic level are not yet clear. Therefore, the aim of the present study was to identify key differential genes between patients with SSc and RA.

Methods

The Gene Expression Omnibus database was used to identify differentially expressed genes (DEGs) between SSc and RA biopsies. The DEGs were then functionally annotated using Gene Ontology (GO) terms and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways with the Database for Annotation, Visualization and Integrated Discovery (DAVID) tools. A protein–protein interaction (PPI) network was constructed with Cytoscape software. The Molecular Complex Detection (MCODE) plugin was also used to evaluate the biological importance of the constructed gene modules.

Results

A total of 13,556 DEGs were identified between the five SSc patients and seven RA patients, including 13,465 up-regulated genes and 91 down-regulated genes. Interestingly, the most significantly enriched GO terms of up- and down-regulated genes were related to extracellular involvement and immune activity, respectively, and the top six highly enriched KEGG pathways were related to the same processes. In the PPI network, the top 10 hub nodes and top four modules harboured the most relevant genes contributing to the differences between SSc and RA, including key genes such as IL6, EGF, JUN, FGF2, BMP2, FOS, BMP4, LRRK2, CTNNB1, EP300, CD79, and CXCL13.

Conclusions

These genes such as IL6, EGF, JUN, FGF2, BMP2, FOS, BMP4, LRRK2, CTNNB1, EP300, CD79, and CXCL13 can serve as new targets for focused research on the distinct molecular pathogenesis of SSc and RA. Furthermore, these genes could serve as potential biomarkers for differential diagnoses or therapeutic targets for treatment.

Electronic supplementary material

The online version of this article (10.1186/s41065-019-0091-y) contains supplementary material, which is available to authorized users.

Proteomic Analysis of Human Scleroderma Fibroblasts Response to Transforming Growth Factor-ß

PURPOSE

Systemic sclerosis (SSc) is characterized by autoimmunity, vasculopathy and fibrosis. Fibrosis is due to an activation of fibroblasts by the transforming growth factor-ß (TGF-ß). This study investigates the proteomic response of SSc fibroblasts to TGF-ß.

EXPERIMENTAL DESIGN

Skin fibroblasts from diffuse SSc patients and healthy controls (HC) are cultured with or without TGF-ß. Two-dimensional differential in-gel electrophoresis and mass spectrometry (MS) combined with Ingenuity Pathway analysis (IPA) and Panther/David software analyze proteins differentially expressed between groups. Real-time cell analyzer (RTCA) assesses fibroblast proliferation and viability.

RESULTS

Two-hundred-and-seventy-nine proteins are differentially expressed between groups. Principal component analysis shows significant differences between groups. IPA shows specific process networks such as actin cytoskeleton and integrin signaling. Panther and David software show predominant biological processes such as cellular and metabolic processes. TGF-ß enhances protein synthesis and protein pathways. IPA and RTCA suggest the involvement of epidermal growth factor receptor (EGFR) and phosphatidylinositol 3 kinase (Pi3K).

CONCLUSIONS AND CLINICAL RELEVANCE

That the proteome of fibroblasts differs between SSc patients and HC is confirmed, and it is demonstrated that fibroblasts exacerbate their proteomic phenotype upon stimulation with TGF-ß. EGFR and Pi3K are highlighted as proteins of interest in SSc fibroblasts.

Systemic Sclerosis and the Gastrointestinal Tract-Clinical Approach

Systemic sclerosis (SSc) is a multisystem disease characterized by functional and structural abnormalities of small blood vessels, fibrosis of the skin and internal organs, immune system activation, and autoimmunity. The gastrointestinal tract is involved in nearly all patients and is a source of significant morbidity and even mortality. The aim of this review is to summarize the pathogenesis and to provide a clinical approach to these patients.

Metabolic fingerprints of human primary endothelial and fibroblast cells

INTRODUCTION

Human primary cells originating from different locations within the body could differ greatly in their metabolic phenotypes, influencing both how they act during physiological/pathological processes and how susceptible/resistant they are to a variety of disease risk factors. A novel way to monitor cellular metabolism is through cell energetics assays, so we explored this approach with human primary cell types, as models of sclerotic disorders.

OBJECTIVES

In order to better understand pathophysiological processes at the cellular level, our goals were to measure metabolic pathway activities of endothelial cells and fibroblasts, and determine their metabolic phenotype profiles.

METHODS

Biolog Phenotype MicroArray™ technology was used for the first time to characterize metabolic phenotypes of diverse primary cells. These colorimetric assays enable detection of utilization of 367 specific biochemical substrates by human endothelial cells from the coronary artery (HCAEC), umbilical vein (HUVEC) and normal, healthy lung fibroblasts (NHLF).

RESULTS

Adenosine, inosine, d-mannose and dextrin were strongly utilized by all three cell types, comparable to glucose. Substrates metabolized solely by HCAEC were mannan, pectin, gelatin and prevalently tricarballylic acid. HUVEC did not show any uniquely metabolized substrates whereas NHLF exhibited strong utilization of sugars and carboxylic acids along with amino acids and peptides.

CONCLUSION

Taken together, we show for the first time that this simple energetics assay platform enables metabolic characterization of primary cells and that each of the three human cell types examined gives a unique and distinguishable profile.

Cytokines in the immunopathology of systemic sclerosis

Cytokines and growth factors are key regulators of immune activation, vascular alteration and excessive production of extracellular matrix which are hallmark events in the pathogenesis of systemic sclerosis (SSc). They modulate cell-cell and cell-matrix interactions. In particular, cytokines play a central role in the immunopathogenesis of SSc on the basis of molecular pathways which are complex and not completely understood. The majority of cytokines that may be involved in SSc pathogenesis have effect upon or are derived from cells of the immune system, including both the innate and adaptive compartments. Novel therapies that block key mediators that drive the fibrotic response are being developed and appear as potential therapeutic tools in the treatment of SSc, highlighting the importance for an effective therapy targeted towards the molecular and cellular pathways. This article reviews cytokine biology in that context, with particular emphasis on immunopathology of the disease, therapeutic targeting and the way that current or emerging treatments for SSc might impact on cytokine biology.

Nintedanib inhibits fibroblast activation and ameliorates fibrosis in preclinical models of systemic sclerosis

BACKGROUND

Nintedanib is a tyrosine kinase inhibitor that has recently been shown to slow disease progression in idiopathic pulmonary fibrosis in two replicate phase III clinical trials. The aim of this study was to analyse the antifibrotic effects of nintedanib in preclinical models of systemic sclerosis (SSc) and to provide a scientific background for clinical trials in SSc.

METHODS

The effects of nintedanib on migration, proliferation, myofibroblast differentiation and release of extracellular matrix of dermal fibroblasts were analysed by microtitre tetrazolium and scratch assays, stress fibre staining, qPCR and SirCol assays. The antifibrotic effects of nintedanib were evaluated in bleomycin-induced skin fibrosis, in a murine sclerodermatous chronic graft-versus-host disease model and in tight-skin-1 mice.

RESULTS

Nintedanib dose-dependently reduced platelet-derived growth factor-induced and transforming growth factor-β-induced proliferation and migration as well as myofibroblast differentiation and collagen release of dermal fibroblasts from patients with and healthy individuals. Nintedanib also inhibited the endogenous activation of SSc fibroblasts. Nintedanib prevented bleomycin-induced skin fibrosis in a dose-dependent manner and was also effective in the treatment of established fibrosis. Moreover, treatment with nintedanib ameliorated fibrosis in the chronic graft-versus-host disease model and in tight-skin-1 mice in well-tolerated doses.

CONCLUSIONS

We demonstrate that nintedanib effectively inhibits the endogenous as well as cytokine-induced activation of SSc fibroblasts and exerts potent antifibrotic effects in different complementary mouse models of SSc. These data have direct translational implications for clinical trials with nintedanib in SSc.

Association of immunological cell profiles with specific clinical phenotypes of scleroderma disease

This study aimed to search the correlation among immunological profiles and clinical phenotypes of scleroderma in well-characterized groups of scleroderma patients, comparing forty-nine scleroderma patients stratified according to specific clinical phenotypes with forty-nine healthy controls. Five immunological cell subpopulations (B, CD4(+) and CD8(+) T-cells, NK, and monocytes) and their respective stages of apoptosis and activation were analyzed by flow cytometry, in samples of peripheral blood mononuclear cells (PBMCs). Analyses of results were stratified according to disease stage, time since the diagnosis, and visceral damage (pulmonary fibrosis, pulmonary hypertension, and cardiac affliction) and by time of treatment with corticosteroids. An increase in the percentages of monocytes and a decrease in the B cells were mainly related to the disease progression. A general apoptosis decrease was found in all phenotypes studied, except in localized scleroderma. An increase of B and NK cells activation was found in patients diagnosed more than 10 years ago. Specific cell populations like monocytes, NK, and B cells were associated with the type of affected organ. This study shows how, in a heterogeneous disease, proper patient's stratification according to clinical phenotypes allows finding specific cellular profiles. Our data may lead to improvements in the knowledge of prognosis factors and to aid in the analysis of future specific therapies.

Is Vasculopathy Associated with Systemic Sclerosis More Severe in Men?

Objective.

To identify possible differences in morbidity and mortality between men and women with systemic sclerosis (SSc) by examining a homogeneous cohort at a single academic center.

Methods.

Demographic, clinical, and outcome data for all 231 patients of Greek origin with SSc who were examined between 1995 and 2011 in our department (200 women) were recorded in consecutive 3-year intervals from disease onset; data were analyzed retrospectively.

Results.

Factors comparable between sexes were age (yrs ± SD) at disease onset (46 ± 15 vs 46 ± 15), diffuse skin involvement (61.3% of men vs 46.4% of women), and anti-Scl-70 antibody positivity (66.6% of men vs 59.2% of women). Also comparable were prevalence of interstitial lung disease, upper or lower gastrointestinal (GI) tract involvement, and echocardiographic findings during the first, second, and third 3-year intervals from disease onset (2904 patient-yrs). In contrast, vasculopathy occurred earlier in men. During the first 3 years digital ulcers developed in 54% of men versus 31% of women (p = 0.036) and renal crisis developed in 17% of men versus 3% of women (p = 0.006). No significant differences regarding social history, smoking, medical history, or disease management were identified. After excluding non-SSc-related deaths, survival was worse in men (p = 0.005, Kaplan-Meier analysis) with significantly lower 6- and 12-year cumulative rates (77.2% and 53.8%, respectively, in men vs 97.3% and 89.2% in women).

Conclusion.

Results derived from an unselected SSc population indicate that the disease is more severely expressed in men than in women, a finding that could be related to more rapid development of vasculopathy in men. Studies are warranted in other single-center cohorts to confirm these findings.