Interferon-alpha does not improve outcome at one year in patients with diffuse cutaneous scleroderma: results of a randomized, double-blind, placebo-controlled trial

Role of rituximab in the treatment of systemic sclerosis: A literature review

This literature review aimed to evaluate the effectiveness of rituximab (RTX) in patients with systemic sclerosis (SSc). PubMed was searched for articles, published through 31 March 2022, on any controlled studies using RTX in the treatment of SSc. Of 85 identified articles, 9 were selected by title/abstract screening and full text examination. All nine articles reported outcomes of forced vital capacity (%FVC), and seven reported those of modified Rodnan skin scores (mRSS). The results showed that among the seven controlled studies evaluating skin lesions in patients with SSc, four showed a significant improvement of mRSS by RTX when compared with a control group, whereas three showed no significant effect. Among the nine controlled studies evaluating lung lesions, five showed a significant improvement of %FVC compared with a control group, whereas four showed no significant effect. In conclusion, RTX may be effective in the treatment of skin and lung lesions in patients with SSc. The profiles of SSc patients for whom RTX was indicated were unclear, although patients with diffuse cutaneous SSc and those positive for anti-topoisomerase I antibody were considered potential targets. Additional studies are needed to assess the long-term effectiveness of RTX in the treatment of patients with SSc.

Heterogeneity and functions of the 13 IFN-α subtypes - lucky for some?

Type I IFNs are critical for host responses to viral infection and are also implicated in the pathogenesis of multiple autoimmune diseases. Multiple subtypes exist within the type I IFN family, in particular 13 distinct IFN-α genes, which signal through the same heterodimer receptor that is ubiquitously expressed by mammalian cells. Both evolutionary genetic studies and functional antiviral assays strongly suggest differential functions and activity between the 13 IFN-α subtypes, yet we still lack a clear understanding of these different roles. This review summarizes the evidence from studies describing differential functions of IFN-α subtypes and highlights potential reasons for discrepancies between the reports. We examine both acute and chronic viral infection, as well as autoimmunity, and integrate a more recent awareness of the importance of anti-IFN-α autoantibodies in shaping the type I IFN responses in these different conditions.

Molecular Mechanisms Behind the Role of Plasmacytoid Dendritic Cells in Systemic Sclerosis

Systemic sclerosis (SSc) is a debilitating autoimmune disease that affects multiple systems. It is characterized by immunological deregulation, functional and structural abnormalities of small blood vessels, and fibrosis of the skin, and, in some cases, internal organs. Fibrosis has a devastating impact on a patient's life and lung fibrosis is associated with high morbimortality. Several immune populations contribute to the progression of SSc, and plasmacytoid dendritic cells (pDCs) have been identified as crucial mediators of fibrosis. Research on murine models of lung and skin fibrosis has shown that pDCs are essential in the development of fibrosis, and that removing pDCs improves fibrosis. pDCs are a subset of dendritic cells (DCs) that are specialized in anti-viral responses and are also involved in autoimmune diseases, such as SSc, systemic lupus erythematosus (SLE) and psoriasis, mostly due to their capacity to produce type I interferon (IFN). A type I IFN signature and high levels of CXCL4, both derived from pDCs, have been associated with poor prognosis in patients with SSc and are correlated with fibrosis. This review will examine the recent research on the molecular mechanisms through which pDCs impact SSc.

Total glucosides of paeony alleviates scleroderma by inhibiting type I interferon responses

ETHNOPHARMACOLOGICAL RELEVANCE

Type I interferon (IFN) is believed to play a pathogenic role in systemic sclerosis (SSc, also called scleroderma), which is an autoimmune rheumatic disease. Our previous studies have found that Chinese medicine formula Si-Ni-San (SNS, composed of Glycyrrhiza uralensis Fisch., Bupleurum chinense DC., Paeonia lactiflora Pall., and Citrus aurantium L.) had inhibitory effects on type I IFN responses. Among these herbal products, Paeonia lactiflora Pall. has been traditionally used to treat inflammation-related diseases, yet its therapeutic effects against type I IFN-related diseases and potential bioactive ingredients are not characterized.

AIM OF THE STUDY

We aim to identify bioactive ingredient with anti-type I IFN activity from herbal products in SNS and further elucidate its therapeutic effect against scleroderma and underlying mechanisms.

MATERIALS AND METHODS

We constructed a Gaussia-luciferase (Gluc) reporter assay system to identify ingredients with anti-type I IFN activities from SNS. In RAW264.7 cells, real-time PCR (RT-PCR) and western blotting were used to investigate the induction of type I IFN pathway. Additionally, in a bleomycin (BLM)-induced experimental scleroderma model, the expression of fibrotic genes, type I IFN-related genes, inflammatory cytokines, and cytotoxic granules were measured by RT-PCR, and the histopathological changes were determined by H&E staining, Masson's staining and immunohistochemistry analysis.

RESULTS

Our data demonstrated that total glucosides of paeony (TGP) was the bioactive component of SNS that selectively inhibited TLR3-mediated type I IFN responses and blocked type I IFN-induced downstream JAK-STAT signaling pathways. In the BLM-induced scleroderma mouse model, TGP ameliorated skin fibrosis by inhibiting multiple targets in the upstream and downstream of type I IFN signaling. Further research found that TGP hindered polarization of M2 macrophages and their profibrotic effects and reduced cytotoxic T lymphocytes and their cytotoxic granules by suppressing Cxcl9 and Cxcl10 in the skin tissue of scleroderma mice.

CONCLUSIONS

Our study not only sheds novel lights into the immunoregulative effects of TGP but also provides convincing evidence to develop TGP-based therapies in the treatment of scleroderma and other autoimmune diseases associated with type I IFN signatures.

CLASSIFICATION

Skin.

Novel role of long non-coding RNAs in autoimmune cutaneous disease

Systemic autoimmune rheumatic diseases (SARDs) are a heterogeneous group of chronic multisystem inflammatory disorders that are thought to have a complex pathophysiology, which is not yet fully understood. Recently, the role of non-coding RNAs, including long non-coding RNA (lncRNA), has been of particular interest in the pathogenesis of SARDs. We aimed to summarize the potential roles of lncRNA in SARDs affecting the skin including, systemic sclerosis (SSc), dermatomyositis (DM) and cutaneous lupus erythematosus (CLE). We conducted a narrative review summarizing original articles published until July 19, 2021, regarding lncRNA associated with SSc, DM, and CLE. Several lncRNAs were hypothesized to play an important role in disease pathogenesis of SSc, DM and CLE. In SSc, Negative Regulator of IFN Response (NRIR) was thought to modulate Interferon (IFN) response in monocytes, anti-sense gene to X-inactivation specific transcript (TSIX) to regulate increased collagen stability, HOX transcript antisense RNA (HOTAIR) to increase numbers of myofibroblasts, OTUD6B-Anti-Sense RNA 1 to decrease fibroblast apoptosis, ncRNA00201 to regulate pathways in SSc pathogenesis and carcinogenesis, H19X potentiating TGF-β-driven extracellular matrix production, and finally PSMB8-AS1 potentiates IFN response. In DM, linc-DGCR6-1 expression was hypothesized to target the USP18 protein, a type 1 IFN-inducible protein that is considered a key regulator of IFN signaling. Additionally, AL136018.1 is suggested to regulate the expression Cathepsin G, which increases the permeability of vascular endothelial cells and the chemotaxis of inflammatory cells in peripheral blood and muscle tissue in DM. Lastly, lnc-MIPOL1-6 and lnc-DDX47-3 in discoid CLE were thought to be associated with the expression of chemokines, which are significant in Th1 mediated disease. In this review, we summarize the key lncRNAs that may drive pathogenesis of these connective tissue diseases and could potentially serve as therapeutic targets in the future.

Type 1 interferon activation in systemic sclerosis: a biomarker, a target or the culprit

PURPOSE OF REVIEW

Activation of the type 1 interferon (T1 IFN) pathway has been implicated in the pathogenesis of systemic sclerosis (SSc) by an increasing number of studies, most of which share key findings with similar studies in systemic lupus erythematosus (SLE). Here we will focus on the evidence for T1 IFN activation and dysregulation in SSc, and the rationale behind targeting the pathway going forward.

RECENT FINDINGS

An increased expression and activation of T1 IFN-regulated genes has been shown to be present in a significant proportion of SSc patients. TI IFN activation markers have been found to predict and correlate with response to immunosuppressive treatment as well as severity of organ involvement. As inhibition of the IFN-α receptor has been proven to be effective in active SLE, benefit may be seen in targeting the IFN pathway in SSc.

SUMMARY

The role played by T1 IFN and its regulatory genes in SSc is becoming increasingly evident and strikingly similar to the role observed in SLE. This observation, together with the benefit of type 1 IFN targeting in SLE, supports the notion of a potential therapeutic benefit in targeting T1 IFN in SSc.

Adenosine-to-inosine RNA editing contributes to type I interferon responses in systemic sclerosis

OBJECTIVE

Adenosine deaminase acting on RNA-1 (ADAR1) enzyme is a type I interferon (IFN)-stimulated gene (ISG) catalyzing the deamination of adenosine-to-inosine, a process called A-to-I RNA editing. A-to-I RNA editing takes place mainly in Alu elements comprising a primate-specific level of post-transcriptional gene regulation. Whether RNA editing is involved in type I IFN responses in systemic sclerosis (SSc) patients remains unknown.

METHODS

ISG expression was quantified in skin biopsies and peripheral blood mononuclear cells derived from SSc patients and healthy subjects. A-to-I RNA editing was examined in the ADAR1-target cathepsin S (CTSS) by an RNA editing assay. The effect of ADAR1 on interferon-α/β-induced CTSS expression was assessed in human endothelial cells in vitro.

RESULTS

Increased expression levels of the RNA editor ADAR1, and specifically the long ADAR1p150 isoform, and its target CTSS are strongly associated with type I IFN signature in skin biopsies and peripheral blood derived from SSc patients. Notably, IFN-α/β-treated human endothelial cells show 8-10-fold increased ADAR1p150 and 23-35-fold increased CTSS expression, while silencing of ADAR1 reduces CTSS expression by 60-70%. In SSc patients, increased RNA editing rate of individual adenosines located in CTSS 3' UTR Alu elements is associated with higher CTSS expression (r = 0.36-0.6, P < 0.05 for all). Similar findings were obtained in subjects with activated type I IFN responses including SLE patients or healthy subjects after influenza vaccination.

CONCLUSION

ADAR1p150-mediated A-to-I RNA editing is critically involved in type I IFN responses highlighting the importance of post-transcriptional regulation of proinflammatory gene expression in systemic autoimmunity, including SSc.

Dysregulation of Type 1 Interferon Signaling in Systemic Sclerosis: a Promising Therapeutic Target?

Purpose of review

There are several lines of evidence at the genetic and gene expression levels linking type I interferon (IFN) activation to systemic sclerosis (SSc) pathogenesis. Herein, we summarize the potential role of type I IFN signaling components as therapeutic targets.

Recent findings

All type I IFN cytokines signal through the interferon-α/β receptor (IFNAR). Early phase studies indicate that anifrolumab (a human monoclonal antibody against IFNAR subunit 1) has an acceptable safety profile and can attenuate transforming growth factor beta (TGF-β)-mediated fibrosis in SSc skin, supporting its further clinical development. Janus kinase (JAK) signaling pathways are downstream from IFNAR. Building on their efficacy in hereditary interferonopathies, JAK inhibitors have the potential to block the deleterious IFN and other profibrotic cytokine activation in SSc and are promising drug targets. Moreover, interferon regulator factor (IRF) 5, 7, and 8 have been linked to the profibrotic response in SSc preclinical studies, underscoring their potential as therapeutic targets. Lastly, depletion of plasmacytoid dendritic cells (pDCs) attenuates the IFN activation and fibrotic response in vitro and murine model experiments and can be studied as a viable drug target in future clinical studies.

Summary

There is increasing evidence linking the prominent type I IFN activation to the observed exaggerated fibrotic response in SSc. Key components of type I IFN signaling are druggable therapeutic targets that can be pursued in future randomized clinical trials, in order to develop more effective therapeutic options for SSc.

Pharmacological insights into autophagy modulation in autoimmune diseases

As a cellular bulk degradation and survival mechanism, autophagy is implicated in diverse biological processes. Genome-wide association studies have revealed the link between autophagy gene polymorphisms and susceptibility of autoimmune diseases including systemic lupus erythematosus (SLE) and inflammatory bowel disease (IBD), indicating that autophagy dysregulation may be involved in the development of autoimmune diseases. A series of autophagy modulators have displayed protective effects on autoimmune disease models, highlighting the emerging role of autophagy modulators in treating autoimmune diseases. This review explores the roles of autophagy in the autoimmune diseases, with emphasis on four major autoimmune diseases [SLE, rheumatoid arthritis (RA), IBD, and experimental autoimmune encephalomyelitis (EAE)]. More importantly, the therapeutic potentials of small molecular autophagy modulators (including autophagy inducers and inhibitors) on autoimmune diseases are comprehensively analyzed.

The Pathogenesis, Molecular Mechanisms, and Therapeutic Potential of the Interferon Pathway in Systemic Lupus Erythematosus and Other Autoimmune Diseases

Therapeutic success in treating patients with systemic lupus erythematosus (SLE) is limited by the multivariate disease etiology, multi-organ presentation, systemic involvement, and complex immunopathogenesis. Agents targeting B-cell differentiation and survival are not efficacious for all patients, indicating a need to target other inflammatory mediators. One such target is the type I interferon pathway. Type I interferons upregulate interferon gene signatures and mediate critical antiviral responses. Dysregulated type I interferon signaling is detectable in many patients with SLE and other autoimmune diseases, and the extent of this dysregulation is associated with disease severity, making type I interferons therapeutically tangible targets. The recent approval of the type I interferon-blocking antibody, anifrolumab, by the US Food and Drug Administration for the treatment of patients with SLE demonstrates the value of targeting this pathway. Nevertheless, the interferon pathway has pleiotropic biology, with multiple cellular targets and signaling components that are incompletely understood. Deconvoluting the complexity of the type I interferon pathway and its intersection with lupus disease pathology will be valuable for further development of targeted SLE therapeutics. This review summarizes the immune mediators of the interferon pathway, its association with disease pathogenesis, and therapeutic modalities targeting the dysregulated interferon pathway.

IFN-α: A key therapeutic target for multiple autoimmune rheumatic diseases

Interferon (IFN)-α has emerged as a major therapeutic target for several autoimmune rheumatic diseases. In this review, we focus on clinical and preclinical advances in anti-IFN-α treatments in systemic lupus erythematosus (SLE), primary Sjögren syndrome (pSS), systemic sclerosis (SSc), and dermatomyositis (DM), for which a high medical need persists. Promising achievements were obtained following direct IFN-α neutralization, targeting its production through the cytosolic nucleic acid sensor pathways or by blocking its downstream effects through the type I IFN receptor. We further focus on molecular profiling and data integration approaches as crucial steps to select patients most likely to benefit from anti-IFN-α therapies within a precision medicine approach.

Durometry in SSc: The hard facts. A systematic literature review and additional pilot study

OBJECTIVES

To investigate the reliability of durometry in systemic sclerosis (SSc), by means of a systematic review and additional pilot study.

METHODS

Literature was systematically reviewed according to the PRISMA guidelines to identify all original studies assessing the reliability of durometry in SSc. Additionally, in the pilot study, intra-rater reliability was evaluated in a first cohort of 74 SSc patients (61 female, 13 LSSc/53 LcSSc/8 DcSSc). In a second separate set of 30 SSc patients (21 female, 4 LSSc/20 LcSSc/6 DcSSc), intra- and inter-rater reliability were evaluated.

RESULTS

Only two unique records identified through the systematic review were qualified to generate conclusions. Regarding intra-rater reliability, Kissin reported excellent intra-class correlation coefficient values (ICC, 0.86-0.94) for measurements at nine skin sites in two DcSSc patients. Merkel and Kissin described, both in five DcSSc patients, good to excellent inter-rater reliability (ICC, 0.82-0.96 and 0.61-0.85) for measurements at respectively, six and nine skin sites. In our pilot study, ICC for intra-rater reliability at 17 standardized skin sites were excellent in both cohorts, ranging 0.93-0.99 and 0.78-0.98, respectively. ICC for inter-rater reliability at 17 standardized skin sites were good to excellent 0.63-0.93, except for the feet (0.48 and 0.52).

CONCLUSION

The preliminary findings in the literature are supported by our pilot study in which we have attested the reliability of durometry in SSc patients. However, prior to including durometry as an (additional) outcome measure in SSc clinical trials, its validation status in the assessment of skin fibrosis needs to be completely attested.

New promising drugs for the treatment of systemic sclerosis: pathogenic considerations, enhanced classifications, and personalized medicine

Introduction: Systemic sclerosis (SSc), also known as scleroderma, is a complex orphan disease characterized by early inflammatory features, vascular hyper-reactivity, and fibrosis of the skin and internal organs. Although substantial progress has been made in the understanding of the pathogenesis of SSc, there is still no disease-modifying drug that could significantly impact the natural history of the disease.Areas covered: This review discusses the rationale, preclinical evidence, first clinical eevidence,and pending issues concerning new promising therapeutic options that are under investigation in SSc. The search strategy was based on PubMed database and clinical trial.gov, highlighting recent key pathogenic aspects and phase I or II trials of investigational drugs in SSc.Expert opinion: The identification of new molecular entities that potentially impact inflammation and fibrosis may constitute promising options for a disease modifying-agent in SSc. The early combinations of antifibrotic drugs (such as pirfenidone) with immunomodulatory agents (such as mycophenolate mofetil) may also participate to achieve such a goal. A more refined stratification of patients, based on clinical features, molecular signatures, and identification of subpopulations with distinct clinical trajectories, may also improve management strategies in the future.

Predictive Significance of Serum Interferon-Inducible Protein Score for Response to Treatment in Systemic Sclerosis-Related Interstitial Lung Disease

OBJECTIVE

Response to immunosuppression is highly variable in systemic sclerosis (SSc)-related interstitial lung disease (ILD). This study was undertaken to determine whether a composite serum interferon (IFN)-inducible protein score exhibits predictive significance for the response to immunosuppression in SSc-ILD.

METHODS

Serum samples collected in the Scleroderma Lung Study II, a randomized controlled trial of mycophenolate mofetil (MMF) versus cyclophosphamide (CYC), were examined. Results were validated in an independent observational cohort receiving active treatment. A composite score of 6 IFN-inducible proteins IFNγ-inducible 10-kd protein, monokine induced by IFNγ, monocyte chemotactic protein 2, β₂ -microglobulin, tumor necrosis factor receptor type II, and macrophage inflammatory protein 3β) was calculated, and its predictive significance for longitudinal forced vital capacity percent predicted measurements was evaluated.

RESULTS

Higher baseline IFN-inducible protein score predicted better response over 3 to 12 months in the MMF arm (point estimate = 0.41, P = 0.001) and CYC arm (point estimate = 0.91, P = 0.009). In contrast, higher baseline C-reactive protein (CRP) levels were predictive of a worse ILD course in both treatment arms. The predictive significance of the IFN-inducible protein score and CRP levels remained after adjustment for baseline demographic and clinical predictors. During the second year of treatment, in which patients in the CYC arm were switched to placebo, a higher IFN-inducible protein score at 12 months showed a trend toward predicting a worse ILD course (point estimate = -0.61, P = 0.068), while it remained predictive of better response to active immunosuppression in the MMF arm (point estimate = 0.28, P = 0.029). The predictive significance of baseline IFN-inducible protein score was replicated in the independent cohort (r_s = 0.43, P = 0.028).

CONCLUSION

A higher IFN-inducible protein score in SSc-ILD is predictive of better response to immunosuppression and could potentially be used to identify patients who may derive the most benefit from MMF or CYC.

Systemic sclerosis (scleroderma): remaining challenges

Despite progress in treating internal organ involvement in systemic sclerosis (scleroderma) (SSc), such as pulmonary disease, effective treatments for the hallmark of the disease, cutaneous fibrosis, remain elusive. None of the disease-modifying antirheumatic drugs (DMARDS) have shown proven efficacy for SSc skin fibrosis, and there remain no FDA-approved medications, all of which are off-label, for cutaneous fibrosis in SSc. This review article will briefly summarize conventional therapies, biologics and hematopoietic stem cell transplants and select ongoing clinical trials in SSc. The gold standard for measuring skin fibrosis in SSc is the modified Rodnan skin score (MRSSS). This is a validated test that measures skin thickness (0 to 3) at 17 locations for a total score of 51. Improvements in skin score over time are used in clinical trials to quantitate skin fibrosis. Although recording the Rodnan skin score is technically straightforward, requiring no special equipment, and noninvasive, the fluctuating natural history of the disease includes improvement over time without interventions, rendering meaningful trials difficult to assess. Understanding of the basic molecular mechanisms driving pathologic fibrosis in SSc remains lacking, and underpins the often empiric nature and likely the lack of efficacy of many therapeutics that have been tried. Although repeated skin biopsies might be a more precise way to follow disease progression and regression, this is necessarily invasive and requires special tools. Here, this review will look at conventional therapies, biologics, autologous hematopoietic stem cell transplantation, and catalog some of the ongoing clinical trials in SSc with a focus on cutaneous fibrosis.

Clinical Treatment Options in Scleroderma: Recommendations and Comprehensive Review

There are two major clinical subsets of scleroderma: (i) systemic sclerosis (SSc) is a complex systemic autoimmune disorder characterized by inflammation, vasculopathy, and excessive fibrosis of the skin and multiple internal organs and (ii) localized scleroderma (LoS), also known as morphea, is confined to the skin and/or subcutaneous tissues resulting in collagen deposition and subsequent fibrosis. SSc is rare but is associated with significant morbidity and mortality compared with other rheumatic diseases. Fatal outcomes in SSc often originate from organ complications of the disease, such as lung fibrosis, pulmonary artery hypertension (PAH), and scleroderma renal crisis (SRC). Current treatment modalities in SSc have focused on targeting vascular damage, fibrosis, and regulation of inflammation as well as autoimmune responses. Some drugs previously used in an attempt to suppress fibrosis, like D-penicillamine (D-Pen) or colchicine, have been disappointing in clinical practice despite anecdotal evidence of their advantages. Some canonical medications, including glucocorticoids, immunosuppressants, and vasodilators, have had some success in treating various manifestations in SSc patients. Increasing evidence suggests that some biologic agents targeting collagen, cytokines, and cell surface molecules might have promising therapeutic effects in SSc. In recent years, hematopoietic stem cell transplantation (HSCT), mostly autologous, has made great progress as a promising treatment option in severe and refractory SSc. Due to the complexity and heterogeneity of SSc, there are currently no optimal treatments for all aspects of the disease. As for LoS, local skin-targeted therapy is generally used, including topical application of glucocorticoids or other immunomodulatory ointments and ultraviolet (UV) irradiation. In addition, systemic immunosuppressants are also utilized in several forms of LoS. Here, we comprehensively discuss current treatment options for scleroderma, encompassing old, new, and future potential treatment options. In addition, we summarize data from new clinical trials that have the potential to modify the disease process and improve long-term outcomes in SSc.

Relating Interferon Regulatory Factor 5 Rs2004640 Gene Polymorphism To Increased Risk Of Systemic Sclerosis In The Patients: Russian Federation Cohort

Background ― A number of studies confirmed a crucial role of type 1 interferon in pathophysiology of connective tissue diseases. Interferon regulatory factors (IRF) coordinate an expression of type 1 interferon, while interferon regulatory factor 5 (IRF5) gene was recently identified as causing predisposition to systemic lupus erythematosus and Sjögren syndrome. The objective of our study was to identify possible association of IRF5 rs2004640 (G/T) single nucleotide polymorphism with systemic sclerosis (SSc). Material and Methods―The study involved 236 individuals, including 105 patients with SSc diagnosis and 131 control individuals from Moscow region. The latter were healthy, unrelated to each other, their genders and ages were matched to those of SSc patients. Allele-specific real-time polymerase chain reaction (PCR) was used to study IFR5 rs2004640 polymorphism. Results ― We detected significantly higher percentage of IRF5 T-allele carriers in all patients (59.5%), those with diffuse cutaneous SSc (67.3%), patients with interstitial lung lesions (62.3%), and those with positive titers of anti-topoisomerase I antibodies (66.3%), compared with control group (46.2%). The odds ratios (OR) were: 1.71 (р=0.00), 2.40 (р=0.0004), 1.93 (р=0.002), and 2.30 (р=0.0008), correspondingly. Conclusion ― The replacement of nucleotide G by T in the IRF5 rs2004640 gene polymorphism was associated with a predisposition to SSc. Our data implied an existence of a novel SSc pathogenetic pathway associated with important role of type 1 interferon in pathophysiology of connective tissue diseases.

Integrated bulk and single-cell RNA-sequencing identified disease-relevant monocytes and a gene network module underlying systemic sclerosis

OBJECTIVE

Immunological disturbances have been reported in systemic sclerosis (SSc). This study assessed the transcriptome disturbances in immune cell subsets in SSc and characterized a disease-related gene network module and immune cell cluster at single cell resolution.

METHODS

Twenty-one Japanese SSc patients were enrolled and compared with 13 age- and sex-matched healthy controls (HC). Nineteen peripheral blood immune cell subsets were sorted by flow cytometry and bulk RNA-seq analysis was performed for each. Differential expression and pathway analyses were conducted. Iterative weighted gene correlation network analysis (iWGCNA) of each subset revealed clustered co-expressed gene network modules. Random forest analysis prioritized a disease-related gene module. Single cell RNA-seq analysis of 878 monocytes was integrated with bulk RNA-seq analysis and with a public database for single cell RNA-seq analysis of SSc patients.

RESULTS

Inflammatory pathway genes were differentially expressed in widespread immune cell subsets of SSc. An inflammatory gene module from CD16⁺ monocytes, which included KLF10, PLAUR, JUNB and JUND, showed the greatest discrimination between SSc and HC. One of the clusters of SSc monocytes identified by single-cell RNA-seq analysis characteristically expressed these inflammatory co-expressed genes and was similar to lung infiltrating FCN1^hi monocytes expressing IL1B.

CONCLUSIONS

Our integrated analysis of bulk and single cell RNA-seq analysis identified an inflammatory gene module and a cluster of monocytes that are relevant to SSc pathophysiology. They could serve as candidate novel therapeutic targets in SSc.

The Pathogenesis of Systemic Sclerosis: An Understanding Based on a Common Pathologic Cascade across Multiple Organs and Additional Organ-Specific Pathologies

Systemic sclerosis (SSc) is a multisystem autoimmune and vascular disease resulting in fibrosis of various organs with unknown etiology. Accumulating evidence suggests that a common pathologic cascade across multiple organs and additional organ-specific pathologies underpin SSc development. The common pathologic cascade starts with vascular injury due to autoimmune attacks and unknown environmental factors. After that, dysregulated angiogenesis and defective vasculogenesis promote vascular structural abnormalities, such as capillary loss and arteriolar stenosis, while aberrantly activated endothelial cells facilitate the infiltration of circulating immune cells into perivascular areas of various organs. Arteriolar stenosis directly causes pulmonary arterial hypertension, scleroderma renal crisis and digital ulcers. Chronic inflammation persistently activates interstitial fibroblasts, leading to the irreversible fibrosis of multiple organs. The common pathologic cascade interacts with a variety of modifying factors in each organ, such as keratinocytes and adipocytes in the skin, esophageal stratified squamous epithelia and myenteric nerve system in gastrointestinal tract, vasospasm of arterioles in the heart and kidney, and microaspiration of gastric content in the lung. To better understand SSc pathogenesis and develop new disease-modifying therapies, it is quite important to understand the complex pathogenesis of SSc from the two distinct perspectives, namely the common pathologic cascade and additional organ-specific pathologies.

Toll-like receptors in mediating pathogenesis in systemic sclerosis

Toll-like receptors (TLRs) are evolutionarily conserved receptors essential for the host defence against pathogens. Both immune and non-immune cells can express TLRs, although at different levels. Systemic sclerosis (SSc) is a chronic disease in which autoimmunity, dysregulated profibrotic mediator release and activation of fibroblasts lead to dysregulated collagen deposition and fibrosis. There is now increasing knowledge that the innate immune system and, in particular, TLRs take a part in SSc pathogenesis. The list of endogenous ligands that can stimulate TLRs in SSc is growing: these ligands represent specific danger-associated molecular patterns (DAMPs), involved either in the initiation or the perpetuation of inflammation, and in the release of factors that sustain the fibrotic process or directly stimulate the cells that produce collagen and the endothelial cells. This review reports evidences concerning TLR signalling involvement in SSc. We report the new DAMPs, as well as the TLR-linked pathways involved in disease, with emphasis on type I interferon signature in SSc, the role of plasmacytoid dendritic cells (pDCs) and platelets. The dissection of the contribution of all these pathways to disease, and their correlation with the disease status, as well as their values as prognostic tools, can help to plan timely intervention and design new drugs for more appropriate therapeutic strategies.

Interferon regulatory factor 7 (IRF7) represents a link between inflammation and fibrosis in the pathogenesis of systemic sclerosis

OBJECTIVES

There is considerable evidence that implicates dysregulation of type I interferon signalling (or type I IFN signature) in the pathogenesis of systemic sclerosis (SSc). Interferon regulatory factor 7 (IRF7) has been recognised as a master regulator of type I IFN signalling. The objective of this study was to elucidate the role of IRF7 in dermal fibrosis and SSc pathogenesis.

METHODS

SSc and healthy control skin biopsies were investigated to determine IRF7 expression and activation. The role of IRF7 in fibrosis was investigated using IRF7 knockout (KO) mice in the bleomycin-induced and TSK/+mouse models. In vitro experiments with dermal fibroblasts from patients with SSc and healthy controls were performed.

RESULTS

IRF7 expression was significantly upregulated and activated in SSc skin tissue and explanted SSc dermal fibroblasts compared with unaffected, matched controls. Moreover, IRF7 expression was stimulated by IFN-α in dermal fibroblasts. Importantly, IRF7 co-immunoprecipitated with Smad3, a key mediator of transforming growth factor (TGF)-β signalling, and IRF7 knockdown reduced profibrotic factors in SSc fibroblasts. IRF7 KO mice demonstrated attenuated dermal fibrosis and inflammation compared with wild-type mice in response to bleomycin. Specifically, hydroxyproline content, dermal thickness as well as Col1a2, ACTA2 and interleukin-6 mRNA levels were significantly attenuated in IRF7 KO mice skin tissue. Furthermore, IRF7 KO in TSK/+mice attenuated hydroxyproline content, subcutaneous hypodermal thickness, Col1a2 mRNA as well as α-smooth muscle actin and fibronectin expression.

CONCLUSIONS

IRF7 is upregulated in SSc skin, interacts with Smad3 and potentiates TGF-β-mediated fibrosis, and therefore may represent a promising therapeutic target in SSc.

The Long Non-coding RNA NRIR Drives IFN-Response in Monocytes: Implication for Systemic Sclerosis

TLR4 activation initiates a signaling cascade leading to the production of type I IFNs and of the downstream IFN-stimulated genes (ISGs). Recently, a number of IFN-induced long non-coding RNAs (lncRNAs) that feed-back regulate the IFN response have been identified. Dysregulation of this process, collectively known as the "Interferon (IFN) Response," represents a common molecular basis in the development of autoimmune and autoinflammatory disorders. Concurrently, alteration of lncRNA profile has been described in several type I IFN-driven autoimmune diseases. In particular, both TLR activation and the upregulation of ISGs in peripheral blood mononuclear cells have been identified as possible contributors to the pathogenesis of systemic sclerosis (SSc), a connective tissue disease characterized by vascular abnormalities, immune activation, and fibrosis. However, hitherto, a potential link between specific lncRNA and the presence of a type I IFN signature remains unclear in SSc. In this study, we identified, by RNA sequencing, a group of lncRNAs related to the IFN and anti-viral response consistently modulated in a type I IFN-dependent manner in human monocytes in response to TLR4 activation by LPS. Remarkably, these lncRNAs were concurrently upregulated in a total of 46 SSc patients in different stages of their disease as compared to 18 healthy controls enrolled in this study. Among these lncRNAs, Negative Regulator of the IFN Response (NRIR) was found significantly upregulated in vivo in SSc monocytes, strongly correlating with the IFN score of SSc patients. Weighted Gene Co-expression Network Analysis showed that NRIR-specific modules, identified in the two datasets, were enriched in "type I IFN" and "viral response" biological processes. Protein coding genes common to the two distinct NRIR modules were selected as putative NRIR target genes. Fifteen in silico-predicted NRIR target genes were experimentally validated in NRIR-silenced monocytes. Remarkably, induction of CXCL10 and CXCL11, two IFN-related chemokines associated with SSc pathogenesis, was reduced in NRIR-knockdown monocytes, while their plasmatic level was increased in SSc patients. Collectively, our data show that NRIR affects the expression of ISGs and that dysregulation of NRIR in SSc monocytes may account, at least in part, for the type I IFN signature present in SSc patients.

Type I interferon dysregulation in Systemic Sclerosis

Systemic Sclerosis (Scleroderma, SSc) is a multifaceted disease characterized by autoimmunity, vasculopathy, and fibrosis affecting the skin and internal organs. Despite advances in the understanding and treatment of SSc in recent years, SSc continues to cause reduced quality of life and premature mortality. Type I interferons (IFNs), a family of cytokines with essential roles in the immune response to microbial infection, play a pathogenic role in certain autoimmune diseases (reviewed elsewhere in this edition). Polymorphisms in interferon-regulatory factors confer an increased risk of SSc, and IFN excess is evident in the blood and skin of a large percentage of SSc patients. Here we describe the evidence of Type I IFN dysregulation in SSc, revealed predominately by genetics and gene expression profiling. We also discuss evidence regarding mechanisms by which Type I IFN might contribute to SSc pathogenesis, mechanisms driving excess Type I IFN production in SSc, and the potential roles of Type I IFNs as biomarkers and therapeutic targets in SSc.

Diagnostic criteria, severity classification and guidelines of systemic sclerosis

Several effective drugs have been identified for the treatment of systemic sclerosis (SSc). However, in advanced cases, not only their effectiveness is reduced but they may be also harmful due to their side-effects. Therefore, early diagnosis and early treatment is most important for the treatment of SSc. We established diagnostic criteria for SSc in 2003 and early diagnostic criteria for SSc in 2011, for the purpose of developing evaluation of each organ in SSc. Moreover, in November 2013, the American College of Rheumatology and the European Rheumatology Association jointly developed new diagnostic criteria for increasing their sensitivity and specificity, so we revised our diagnostic criteria and severity classification of SSc. Furthermore, we have revised the clinical guideline based on the newest evidence. In particular, the clinical guideline was established by clinical questions based on evidence-based medicine according to the New Minds Clinical Practice Guideline Creation Manual (version 1.0). We aimed to make the guideline easy to use and reliable based on the newest evidence, and to present guidance as specific as possible for various clinical problems in treatment of SSc.

Patterns and predictors of skin score change in early diffuse systemic sclerosis from the European Scleroderma Observational Study

OBJECTIVES

Our aim was to use the opportunity provided by the European Scleroderma Observational Study to (1) identify and describe those patients with early diffuse cutaneous systemic sclerosis (dcSSc) with progressive skin thickness, and (2) derive prediction models for progression over 12 months, to inform future randomised controlled trials (RCTs).

METHODS

The modified Rodnan skin score (mRSS) was recorded every 3 months in 326 patients. 'Progressors' were defined as those experiencing a 5-unit and 25% increase in mRSS score over 12 months (±3 months). Logistic models were fitted to predict progression and, using receiver operating characteristic (ROC) curves, were compared on the basis of the area under curve (AUC), accuracy and positive predictive value (PPV).

RESULTS

66 patients (22.5%) progressed, 227 (77.5%) did not (33 could not have their status assessed due to insufficient data). Progressors had shorter disease duration (median 8.1 vs 12.6 months, P=0.001) and lower mRSS (median 19 vs 21 units, P=0.030) than non-progressors. Skin score was highest, and peaked earliest, in the anti-RNA polymerase III (Pol3+) subgroup (n=50). A first predictive model (including mRSS, duration of skin thickening and their interaction) had an accuracy of 60.9%, AUC of 0.666 and PPV of 33.8%. By adding a variable for Pol3 positivity, the model reached an accuracy of 71%, AUC of 0.711 and PPV of 41%.

CONCLUSIONS

Two prediction models for progressive skin thickening were derived, for use both in clinical practice and for cohort enrichment in RCTs. These models will inform recruitment into the many clinical trials of dcSSc projected for the coming years.

TRIAL REGISTRATION NUMBER

NCT02339441.

Type I interferon in rheumatic diseases

The type I interferon pathway has been implicated in the pathogenesis of a number of rheumatic diseases, including systemic lupus erythematosus, Sjögren syndrome, myositis, systemic sclerosis, and rheumatoid arthritis. In normal immune responses, type I interferons have a critical role in the defence against viruses, yet in many rheumatic diseases, large subgroups of patients demonstrate persistent activation of the type I interferon pathway. Genetic variations in type I interferon-related genes are risk factors for some rheumatic diseases, and can explain some of the heterogeneity in type I interferon responses seen between patients within a given disease. Inappropriate activation of the immune response via Toll-like receptors and other nucleic acid sensors also contributes to the dysregulation of the type I interferon pathway in a number of rheumatic diseases. Theoretically, differences in type I interferon activity between patients might predict response to immune-based therapies, as has been demonstrated for rheumatoid arthritis. A number of type I interferon and type I interferon pathway blocking therapies are currently in clinical trials, the results of which are promising thus far. This Review provides an overview of the many ways in which the type I interferon system affects rheumatic diseases.

Interferon-induced pulmonary hypertension: an update

PURPOSE OF REVIEW

Pulmonary adverse effects of interferon (IFN) therapies are rare but can be life threatening. This article proposes to review clinical and experimental data suggesting a causal link between interferon exposure and pulmonary arterial hypertension (PAH).

RECENT FINDINGS

Interferon has recently been added to the list of possible risk factors for PAH. This was justified by the reporting of many cases of pulmonary hypertension potentially associated with IFN-α or IFN-β exposure. Some of them were reversible after cessation of interferon exposure, especially in patients without concomitant risk factors for pulmonary hypertension. In contrast, it remains a challenge to definitively confirm the causal role of IFN-α in patients treated for hepatitis C viral infection because of frequent concomitant PAH risk factors such as portal hypertension and/or HIV infection. In these patients, temporal and clinical arguments suggest that interferon may potentially act as an additional trigger for PAH. Moreover, the information obtained from clinical experience with interferon therapy has been enriched by basic science research on this topic suggesting that interferon is involved in both human and experimental pulmonary hypertension.

SUMMARY

Many clinical and experimental data corroborate the link between interferon exposure and the risk to develop PAH.

Assessment of skin involvement in systemic sclerosis

Skin involvement in SSc is an important marker of disease activity, severity and prognosis, making the assessment of skin a key issue in SSc clinical research. We reviewed the published data assessing skin involvement in clinical trials and summarized the major conclusions important in SSc clinical research. A systematic literature review identified randomized controlled trials using skin outcomes in SSc. Analysis examined the validity of the different skin measures based on literature findings. Twenty-two randomized controlled trials were found. The average study duration was 10.2 (s.d. 4.5) months, mean (s.d.) sample size 32.4 (32.6) and 26.7 (27.8) in intervention and control arms, respectively. The 17-site modified Rodnan skin score is a fully validated primary outcome measure in diffuse cutaneous SSc. Skin histology seems to be an appropriate method for evaluation of skin thickness. These findings have important implications for clinical trial design targeting skin involvement in SSc.

Cardiac fibroblast transcriptome analyses support a role for interferogenic, profibrotic, and inflammatory genes in anti-SSA/Ro-associated congenital heart block

The signature lesion of SSA/Ro autoantibody-associated congenital heart block (CHB) is fibrosis and a macrophage infiltrate, supporting an experimental focus on cues influencing the fibroblast component. The transcriptomes of human fetal cardiac fibroblasts were analyzed using two complementary approaches. Cardiac injury conditions were simulated in vitro by incubating human fetal cardiac fibroblasts with supernatants from macrophages transfected with the SSA/Ro-associated noncoding Y ssRNA. The top 10 upregulated transcripts in the stimulated fibroblasts reflected a type I interferon (IFN) response [e.g., IFN-induced protein 44-like (IFI44L), of MX dynamin-like GTPase (MX)1, MX2, and radical S-adenosyl methionine domain containing 2 (Rsad2)]. Within the fibrotic pathway, transcript levels of endothelin-1 (EDN1), phosphodiesterase (PDE)4D, chemokine (C-X-C motif) ligand (CXCL)2, and CXCL3 were upregulated, while others, including adenomedullin, RAP guanine nucleotide exchange factor 3 (RAPGEF3), tissue inhibitor of metalloproteinase (TIMP)1, TIMP3, and dual specificity phosphatase 1, were downregulated. Agnostic Database for Annotation, Visualization and Integrated Discovery analysis revealed a significant increase in inflammatory genes, including complement C3A receptor 1 (C3AR1), F2R-like thrombin/trypsin receptor 3, and neutrophil cytosolic factor 2. In addition, stimulated fibroblasts expressed high levels of phospho-MADS box transcription enhancer factor 2 [a substrate of MAPK5 (ERK5)], which was inhibited by BIX-02189, a specific inhibitor of ERK5. Translation to human disease leveraged an unprecedented opportunity to interrogate the transcriptome of fibroblasts freshly isolated and cell sorted without stimulation from a fetal heart with CHB and a matched healthy heart. Consistent with the in vitro data, five IFN response genes were among the top 10 most highly expressed transcripts in CHB fibroblasts. In addition, the expression of matrix-related genes reflected fibrosis. These data support the novel finding that cardiac injury in CHB may occur secondary to abnormal remodeling due in part to upregulation of type 1 IFN response genes.NEW & NOTEWORTHY Congenital heart block is a rare disease of the fetal heart associated with maternal anti-Ro autoantibodies which can result in death and for survivors, lifelong pacing. This study provides in vivo and in vitro transcriptome-support that injury may be mediated by an effect of Type I Interferon on fetal fibroblasts.

Is Tolerance Broken in Autoimmunity?

Autoimmune diseases are classified into about 80 different types based on their specificity related to system, organ and/or tissue. About 5% of the western population is affected by this anomaly, but its worldwide incidence is unknown. Autoimmune diseases are heterogeneous in nature and clinical manifestations range from benign disorders to life-threatening conditions. Autoimmunity strikes at any stage of life, but age and/or gender also play role in onset of some of these anomalies. The autoimmune pathogenesis is initiated by the origination of autoantigens, which leads to the development of autoantibodies followed by auto-immunogenicity and the ultimate onset of autoimmunity. There is a lack of suitable therapies to treat autoimmune diseases, because mechanisms involved in the onset of these anomalies were poorly understood. Present therapies are limited to symptomatic treatment and come with severe side effects. Here, I described the molecular mechanisms and cellular events involved in the initiation of autoimmunity and proposed better strategies to modulate such molecular and cellular anomalies, which will help in preventing and/or controlling autoimmune pathogenesis and ultimately aid in enhancing the quality of life.

Crosstalk Between Apoptosis and Autophagy: Environmental Genotoxins, Infection, and Innate Immunity

Autoimmune disorders constitute a major and growing health concern. However, the genetic and environmental factors that contribute to or exacerbate disease symptoms remain unclear. Type I interferons (IFNs) are known to break immune tolerance and be elevated in the serum of patients with autoimmune diseases such as lupus. Extensive work over the past decade has characterized the role of a protein termed stimulator of interferon genes, or STING, in mediating IFN expression and activation in response to cytosolic DNA and cyclic dinucleotides. Interestingly, this STING-dependent innate immune pathway both utilizes and is targeted by the cell's autophagic machinery. Given that aberrant interplay between the apoptotic and autophagic machineries contributes to deregulation of the STING-dependent pathway, IFN-regulated autoimmune phenotypes may be influenced by the combined exposure to environmental carcinogens and pathogenic microorganisms and viruses. This review therefore summarizes recent data regarding these important issues in the field of autoimmunity.

Targeted Therapy in Systemic Sclerosis

Targeted therapies use an understanding of the pathophysiology of a disease in an individual patient. Although targeted therapy for systemic sclerosis (SSc, scleroderma) has not yet reached the level of patient-specific treatments, recent developments in the understanding of the global pathophysiology of the disease have led to new treatments based on the cells and pathways that have been shown to be involved in the disease pathogenesis. The presence of a B cell signature in skin biopsies has led to the trial of rituximab, an anti-CD20 antibody, in SSc. The well-known properties of transforming growth factor (TGF)-β in promoting collagen synthesis and secretion has led to a small trial of fresolimumab, a human IgG4 monoclonal antibody capable of neutralizing TGF-β. Evidence supporting important roles for interleukin-6 in the pathogenesis of SSc have led to a large trial of tocilizumab in SSc. Soluble guanylate cyclase (sGC) is an enzyme that catalyzes the production of cyclic guanosine monophosphate (cGMP) upon binding of nitric oxide (NO) to the sGC molecule. Processes such as cell growth and proliferation are regulated by cGMP. Evidence that sGC may play a role in SSc has led to a trial of riociguat, a molecule that sensitizes sGC to endogenous NO. Tyrosine kinases (TKs) are involved in a wide variety of physiologic and pathological processes including vascular remodeling and fibrogenesis such as occurs in SSc. This has led to a trial of nintedanib, a next-generation tyrosine-kinase (TK) inhibitor which targets multiple TKs, in SSc.

A potential contribution of antimicrobial peptide LL-37 to tissue fibrosis and vasculopathy in systemic sclerosis

BACKGROUND

LL-37 is an antimicrobial peptide with pleiotropic effects on the immune system, angiogenesis and tissue remodelling. These are cardinal pathological events in systemic sclerosis (SSc).

OBJECTIVES

To elucidate the potential role of LL-37 in SSc.

METHODS

The expression of target molecules was evaluated by immunostaining and quantitative reverse-transcription real-time polymerase chain reaction in human and murine skin. The mechanisms regulating LL-37 expression in endothelial cells were examined by gene silencing and chromatin immunoprecipitation. Serum LL-37 levels were determined by enzyme-linked immunosorbent assay.

RESULTS

In SSc lesional skin, LL-37 expression was increased in dermal fibroblasts, perivascular inflammatory cells, keratinocytes and, particularly, dermal small vessels. Expression positively correlated with interferon-α expression, possibly reflecting LL-37-dependent induction of interferon-α. In SSc animal models, bleomycin-treated skin exhibited the expression pattern of CRAMP, a murine homologue of LL-37, similar to that of LL-37 in SSc lesional skin. Furthermore, Fli1^+/- mice showed upregulated expression of CRAMP in dermal small vessels. Fli1 binding to the CAMP (LL-37 gene) promoter and Fli1 deficiency-dependent induction of LL-37 were also confirmed in human dermal microvascular endothelial cells. In the analysis of sera, patients with SSc had serum LL-37 levels significantly higher than in healthy controls. Furthermore, serum LL-37 levels positively correlated with skin score and the activity of alveolitis and were significantly elevated in patients with digital ulcers compared with those without.

CONCLUSIONS

LL-37 upregulation, induced by Fli1 deficiency at least in endothelial cells, potentially contributes to the development of skin sclerosis, interstitial lung disease and digital ulcers in SSc.

Interstitial Lung Disease in Systemic Sclerosis

Interstitial lung disease is an early and serious complication of systemic sclerosis (SSc). Because it may be asymptomatic for a long period, and only the early (logistic phase is at present susceptible to treatment, early diagnosis and identification of risk are critical to the outcome. However, identifying SSc patients at risk for developing interstitial lung disease is at present difficult; therefore, a strict monitoring of the disease, especially in the first years, is mandatory. Treatment strategy is aimed at suppressing inflammation. Unfortunately, optimal therapy has not yet been established. Combination of corticosteroids and cyclophosphamide is considered the best therapeutic approach available so far, but doses and duration of treatment need to be determined. Future research should focus on new anti-inflammatory or immunosuppressive agents.

Management of Systemic Sclerosis-Related Skin Disease: A Review of Existing and Experimental Therapeutic Approaches

The skin is the most common organ system involved in patients with systemic sclerosis (SSc). Nearly all patients experience cutaneous symptoms, including sclerosis, Raynaud's phenomenon, digital ulcers, telangiectasias, and calcinosis. In addition to posing functional challenges, cutaneous symptoms are often a major cause of pain, psychological distress, and body image dissatisfaction. The present article reviews the main features of SSc-related cutaneous manifestations and highlights an evidence-based treatment approach for treating each manifestation. This article also describes novel treatment approaches and opportunities for further research in managing this important clinical dimension of SSc.

Experimentally-derived fibroblast gene signatures identify molecular pathways associated with distinct subsets of systemic sclerosis patients in three independent cohorts

Genome-wide expression profiling in systemic sclerosis (SSc) has identified four ‘intrinsic’ subsets of disease (fibroproliferative, inflammatory, limited, and normal-like), each of which shows deregulation of distinct signaling pathways; however, the full set of pathways contributing to this differential gene expression has not been fully elucidated. Here we examine experimentally derived gene expression signatures in dermal fibroblasts for thirteen different signaling pathways implicated in SSc pathogenesis. These data show distinct and overlapping sets of genes induced by each pathway, allowing for a better understanding of the molecular relationship between profibrotic and immune signaling networks. Pathway-specific gene signatures were analyzed across a compendium of microarray datasets consisting of skin biopsies from three independent cohorts representing 80 SSc patients, 4 morphea, and 26 controls. IFNα signaling showed a strong association with early disease, while TGFβ signaling spanned the fibroproliferative and inflammatory subsets, was associated with worse MRSS, and was higher in lesional than non-lesional skin. The fibroproliferative subset was most strongly associated with PDGF signaling, while the inflammatory subset demonstrated strong activation of innate immune pathways including TLR signaling upstream of NF-κB. The limited and normal-like subsets did not show associations with fibrotic and inflammatory mediators such as TGFβ and TNFα. The normal-like subset showed high expression of genes associated with lipid signaling, which was absent in the inflammatory and limited subsets. Together, these data suggest a model by which IFNα is involved in early disease pathology, and disease severity is associated with active TGFβ signaling.

Pulmonary arterial hypertension in patients treated with interferon

Isolated cases of pulmonary arterial hypertension (PAH) in patients treated with interferon (IFN) α or β have been reported in the literature. The aim of this study was to describe all consecutive cases of PAH patients with a history of IFN exposure identified in the French reference centre for severe pulmonary hypertension between 1998 and 2012. A total of 53 patients with PAH and a history of IFN therapy were identified. 48 patients had been treated with IFNα for chronic hepatitis C. Most of them had portal hypertension (85%) and 56% had HIV co-infection. Five additional patients had been treated with IFNβ for multiple sclerosis. The diagnosis of PAH was made within 3 years after IFN therapy in 66% of patients. Repeated haemodynamic assessment was available in 13 out of 16 patients exposed to IFN after the diagnosis of PAH. Increased pulmonary vascular resistance >20% was observed in 11 out of 13 cases (median 43% increase; IQR 32-67%). In five of these patients, IFN withdrawal resulted in spontaneous haemodynamic improvement. This retrospective analysis suggests that IFN therapy may trigger PAH. However, most of these patients had other risk factors for PAH. A prospective case-control study is necessary to definitively establish a link between IFN exposure and PAH.

Old medications and new targeted therapies in systemic sclerosis

SSc is a multiorgan disease with significant morbidity that is associated with poor health-related quality of life. Treatment of this condition is often organ based and non-curative. However, there are newer, potentially disease-modifying therapies available to treat certain aspects of the disease. This review focuses on old and new therapies in the management of SSc in clinical practice.

The role of type 1 interferon in systemic sclerosis

Systemic Sclerosis (Scleroderma, SSc) is an autoimmune disease characterized by vasculopathy, inflammation, and fibrosis that can lead to loss of organ function. Type I interferons (IFNs) are family of cytokines that mitigate the deleterious effects of viral and bacterial infections in the innate immunity system. Past several years, research efforts have been focused on the role of type I IFN and IFN-inducible genes in the pathogenesis of SSc. Polymorphisms in the Interferon regulatory factor (IRF)-5, IRF7, and IRF8 are associated with SSc, Similarly, polymorphism of Signal Transducer and Activator of Transcription (STAT)-4, has been established as a genetic risk factor of SSc. IRFs and STAT4 proteins are key activators of type I IFN signaling pathways. An IFN signature (increased expression and activation of IFN-regulated genes) has been observed in the peripheral blood and skin biopsy samples of patients with SSc. Furthermore, a plasma IFN-inducible chemokine score correlated with markers of disease severity and autoantibody subtypes in SSc. In this review, we summarize our current knowledge of the role of type I IFNs and IFN-inducible genes in the pathogenesis of SSc and their potential role as biomarkers and therapeutic targets.

Microarray profiling reveals suppressed interferon stimulated gene program in fibroblasts from scleroderma-associated interstitial lung disease

BACKGROUND

Interstitial lung disease is a major cause of morbidity and mortality in systemic sclerosis (SSc), with insufficiently effective treatment options. Progression of pulmonary fibrosis involves expanding populations of fibroblasts, and the accumulation of extracellular matrix proteins. Characterisation of SSc lung fibroblast gene expression profiles underlying the fibrotic cell phenotype could enable a better understanding of the processes leading to the progressive build-up of scar tissue in the lungs. In this study we evaluate the transcriptomes of fibroblasts isolated from SSc lung biopsies at the time of diagnosis, compared with those from control lungs.

METHODS

We used Affymetrix oligonucleotide microarrays to compare the gene expression profile of pulmonary fibroblasts cultured from 8 patients with pulmonary fibrosis associated with SSc (SSc-ILD), with those from control lung tissue peripheral to resected cancer (n=10). Fibroblast cultures from 3 patients with idiopathic pulmonary fibrosis (IPF) were included as a further comparison. Genes differentially expressed were identified using two separate analysis programs following a set of pre-determined criteria: only genes significant in both analyses were considered. Microarray expression data was verified by qRT-PCR and/or western blot analysis.

RESULTS

A total of 843 genes were identified as differentially expressed in pulmonary fibroblasts from SSc-ILD and/or IPF compared to control lung, with a large overlap in the expression profiles of both diseases. We observed increased expression of a TGF-β response signature including fibrosis associated genes and myofibroblast markers, with marked heterogeneity across samples. Strongly suppressed expression of interferon stimulated genes, including antiviral, chemokine, and MHC class 1 genes, was uniformly observed in fibrotic fibroblasts. This expression profile includes key regulators and mediators of the interferon response, such as STAT1, and CXCL10, and was also independent of disease group.

CONCLUSIONS

This study identified a strongly suppressed interferon-stimulated gene program in fibroblasts from fibrotic lung. The data suggests that the repressed expression of interferon-stimulated genes may underpin critical aspects of the profibrotic fibroblast phenotype, identifying an area in pulmonary fibrosis that requires further investigation.

Correlation of interferon-inducible chemokine plasma levels with disease severity in systemic sclerosis

OBJECTIVE

To measure interferon (IFN)-inducible chemokines in the plasma of patients with systemic sclerosis (SSc) and investigate whether the chemokine levels are correlated with disease severity.

METHODS

Plasma levels of the IFN-inducible chemokines IFNγ-inducible protein 10 (IP-10/CXCL10), IFN-inducible T cell α chemoattractant (I-TAC/CXCL11), and monocyte chemoattractant protein 1 (CCL2) were measured in SSc patients and examined for correlation with the IFN gene expression signature. A composite IFN-inducible chemokine score was generated for chemokines showing a correlation with the IFN gene signature (IP-10 and I-TAC), and this score was compared between 266 patients with SSc enrolled in the Genetics versus Environment in Scleroderma Outcome Study (GENISOS) cohort and 97 matched control subjects. Subsequently, the correlation between the IFN-inducible chemokine score at baseline and markers of disease severity was assessed. In addition, the course of the IFN-inducible chemokine score over time was examined.

RESULTS

The plasma IFN-inducible chemokine score correlated with the IFN gene expression signature, and this score was higher in SSc patients compared to controls. The IFN-inducible chemokine score was also associated with the absence of anti-RNA polymerase III antibodies and presence of anti-U1 RNP antibodies, but not with disease duration, disease type, or other autoantibodies. The chemokine score correlated with concomitantly obtained scores on the Medsger Severity Index for muscle, skin, and lung involvement in SSc, as well as the forced vital capacity, diffusing capacity for carbon monoxide, and creatine kinase levels. The association of the chemokine score with disease severity was independent of the presence of anti-U1 RNP or other potential confounders (age, sex, ethnicity, disease duration, and treatment with immunosuppressive agents). Finally, there was not a significant change in the IFN-inducible chemokine score over time.

CONCLUSION

The IFN-inducible chemokine score is a stable serologic marker of a more severe form of SSc and may be useful for risk stratification of patients, regardless of disease type (limited or diffuse) or duration of disease.

Patterns and predictors of change in outcome measures in clinical trials in scleroderma: an individual patient meta-analysis of 629 subjects with diffuse cutaneous systemic sclerosis

OBJECTIVE

To examine the range and responsiveness to change of clinical outcome measures and study predictors of clinical response in patients with diffuse cutaneous systemic sclerosis (dcSSc) in the context of clinical trials.

METHODS

Data were combined from 629 patients with dcSSc who participated in 7 multicenter clinical therapeutic trials. Trials used common outcome measures: modified Rodnan skin thickness score (MRSS), Health Assessment Questionnaire disability index (HAQ DI), patient's global assessment of disease activity, pulmonary function tests (forced vital capacity, diffusing capacity for carbon monoxide), hand span, and oral aperture.

RESULTS

The combined database included 629 patients (82% women, mean ± SD age 46.5 ± 11.8 years, mean ± SD disease duration 19.4 ± 15.9 months). Outcomes tended to improve during trials for patients with more severe disease at study entry and to worsen for patients with less severe disease at entry. Disease duration was mildly negatively predictive of change in MRSS at 6 months (r = -0.27, P < 0.001), and substantial bidirectional variation in change in MRSS and HAQ DI score was seen across the spectrum of disease duration. Sixty-three percent of patients with "early" disease (disease duration <18 months) had a decline in MRSS, and 37% had an increase in MRSS. Eighty-one percent of patients with "late" disease (disease duration ≥ 18 months) had a decline in MRSS, and 19% had an increase in MRSS. Multivariate mixed models did not demonstrate that any baseline variables were strongly predictive of subsequent outcome.

CONCLUSION

Among patients with dcSSc enrolled in clinical trials, standard outcome measures tend to improve in those with more severe disease at study entry and to worsen in those with less severe disease at entry. Overall, the MRSS improves during trials, while HAQ DI scores and lung function are mostly static. None of these variables, including disease duration, reliably identifies groups of subjects whose MRSS will predictably increase or decrease in the course of a clinical trial. These findings have important implications for clinical trial design in scleroderma.

Scleroderma therapy: clinical overview of current trends and future perspective

Systemic sclerosis is a chronic autoimmune condition with a complex pathogenesis and a high rate of mortality and morbidity. Internal organ involvement requires interdisciplinary approach in individual patient management. New discoveries in the pathogenesis of scleroderma herald a drastic change in the traditional outlook to therapy and have led to the development of the target-based approach in management. The challenge at present is to translate these advances in molecular mechanisms into well-designed clinical trials that will recognize potential disease-modifying therapies. This article is an evidence-based review of prevailing treatment options and future therapeutic targets in systemic sclerosis.

New insights into the mechanisms of innate immune receptor signalling in fibrosis

Recent advances in our understanding of innate immunity and inflammation have direct bearing on how we understand autoimmunity, and fibrosis, and how innate immune sensors might stimulate both of these key features of several fibrotic diseases. Toll-like receptors (TLRs) are the major receptors for recognizing pathogen associated molecular patterns present on bacterial cell walls, such as LPS, and nucleic acids (RNA and DNA). Several intracellular pathways mediate TLR effects and initiate various pro-inflammatory programs. Mechanisms for control of inflammation, matrix remodeling, and ultimately fibrosis are also activated. Transforming growth factor-beta (TGF-β), Interleukin-1 (IL-1), interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-13 (IL-13), and interferon (IFNs) appear particularly important in regulating pro-fibrotic aspects of innate immune activation. These mechanisms appear important in fibrotic disease affecting multiple organ-systems, including lung, liver, kidney, and skin. These observations provide new paradigms for understanding the relationship between immunity/inflammation and fibrosis, however, the precise ligand and mechanism linking innate immune sensor(s) to fibrosis remain uncertain in most illnesses.

Potential immunologic targets for treating fibrosis in systemic sclerosis: a review focused on leukocytes and cytokines

OBJECTIVES

Systemic sclerosis (SSc) is a connective tissue disease characterized by tissue fibrosis. Although the pathogenesis remains unclear, a variety of cells contribute to the fibrotic process via interactions with each other and production of various cytokines. Recent literature related to the immunologic pathogenesis and future strategies for treating the fibrosis of SSc are discussed and, especially, this literature-based review that includes the authors' perspective, focused on leukocytes and cytokines.

METHODS

A PubMed search for articles published between January 2005 and January 2012 was conducted using the following keywords: systemic sclerosis, leukocyte, cytokine, growth factor, and chemokine. The reference lists of identified articles were searched for further articles.

RESULTS

Targeting profibrogenic cytokines, including transforming growth factor-β, is still a very active area of research in SSc and most cellular studies have focused on the roles of fibroblasts in SSc. However, a growing number of recent studies indicate a role for B cells in the development of SSc and other autoimmune diseases such as systemic lupus erythematosus. Therefore, B-cell-targeted therapies, including currently available monoclonal antibodies against CD19, CD20, CD22, and B-cell-activating factor, belonging to the tumor necrosis factor family represent possible treatment options. Furthermore, the modulation of T-cell costimulatory molecules such as a recombinant fusion protein of cytotoxic T-lymphocyte antigen-4 may be as effective in SSc as it is in treating other autoimmune diseases. Approaches to antagonize interleukin (IL)-1, IL-6, or IL-17A signaling may also be attractive.

CONCLUSIONS

This review describes recent advances in the treatment of fibrosis in SSc patients focused on immunologic strategies, such as leukocyte- or cytokine-targeted therapies.