Metabolic control of BRISC-SHMT2 assembly regulates immune signalling.

Serine hydroxymethyltransferase 2 (SHMT2) regulates one-carbon transfer reactions that are essential for amino acid and nucleotide metabolism, and uses pyridoxal-5'-phosphate (PLP) as a cofactor. Apo SHMT2 exists as a dimer with unknown functions, whereas PLP binding stabilizes the active tetrameric state. SHMT2 also promotes inflammatory cytokine signalling by interacting with the deubiquitylating BRCC36 isopeptidase complex (BRISC), although it is unclear whether this function relates to metabolism. Here we present the cryo-electron microscopy structure of the human BRISC-SHMT2 complex at a resolution of 3.8 Å. BRISC is a U-shaped dimer of four subunits, and SHMT2 sterically blocks the BRCC36 active site and inhibits deubiquitylase activity. Only the inactive SHMT2 dimer-and not the active PLP-bound tetramer-binds and inhibits BRISC. Mutations in BRISC that disrupt SHMT2 binding impair type I interferon signalling in response to inflammatory stimuli. Intracellular levels of PLP regulate the interaction between BRISC and SHMT2, as well as inflammatory cytokine responses. These data reveal a mechanism in which metabolites regulate deubiquitylase activity and inflammatory signalling.

Concordance and Prognostic Relevance of Different Definitions of Systemic Sclerosis Interstitial Lung Disease Progression.

RATIONALE: Interstitial lung disease (ILD) in systemic sclerosis (SSc) is a common complication that has varied progression rate and prognosis. Different progression definitions are available: include minimal clinically important worsening of forced vital capacity (FVC MCIW), EUSTAR (EUropean Scleroderma Trials and Research group) progression, OMERACT (Outcome Measures in Rheumatology Clinical Trials) progression, and Erice ILD working group progression. Pulmonary function and symptoms changes may act as specific confounding factors applying these definitions in SSc. OBJECTIVE: To assess the concordance and prognostic value of four different definitions in SSc-ILD patients overall and specific clinical groups. METHODS: Progression status in consecutive SSc-ILD patients was assessed over 24 months, 60-month disease-related mortality risk was compared between progressors and non-progressors using the four definitions. RESULTS: Among 245 patients, 26 SSc-related deaths were reported. Mortality was linked to progression for FVC MCIW (HR 2.27, 95% CI 1.03-4.97), OMERACT (HR 2.90, 95% CI 1.28-6.57), and Erice definitions (HR 11.02, 95% CI 2.38-51.08). The association between progression and mortality was poor in patients with disease duration ≥3 years, mild functional impairment, and pulmonary artery systolic pressure (PASP)≥40 mmHg. Erice criteria appeared superior in patients with duration ≥3 years, limited cutaneous variant, and PASP<40 mmHg. OMERACT criteria performed better in diffuse cutaneous variant patients with severe functional impairment. CONCLUSIONS: The four evaluated definitions of progression in SSc-ILD are not interchangeable, resulting in up to a third of cases being classified differently based on the adopted criteria, and presenting different prognostic values, particularly within specific clinical groups.

Advances in the diagnosis of multiorgan involvement in systemic sclerosis: a focus on MRI.

PURPOSE OF REVIEW: Systemic sclerosis (SSc) is a rare chronic multisystem autoimmune disease characterized by endothelial dysfunction, tissue hypoxia, and diffuse organ fibrosis. MRI provides a radiation free approach to noninvasively assess the key manifestations of SSc in multiple organs. The purpose of this review is to summarize recent advances in MRI techniques to provide diagnostic and prognostic information in patients with SSc. RECENT FINDINGS: MRI can probe processes that play a key role in the development of SSc-related complications, including neointima proliferation, fibrosis, and hypoxia. Feature tracking and parametric mapping MRI can detect cardiac involvement at the subclinical level. Contrast-free MRI angiography with Digital Artery Volume Index (DAVIX) assessment allow comprehensive assessment of hand involvement. T1 mapping and BOLD imaging can assess SSc effects on skeletal muscle, and lung MRI is becoming a key method for imaging of interstitial lung disease. As a new exciting application, the sodium content of the skin can be quantified by 23Na MRI reflective of glycosaminoglycan content. SUMMARY: Recent advances in MRI provide a unique opportunity to study the key pathophysiologic processes and clinical manifestations of SSc in multiple organs noninvasively, which can pave the way for the development of effective therapies.

Gastrointestinal disease in systemic sclerosis: the neglected organ system?

PURPOSE OF REVIEW: Identifying outcomes and clinical trial endpoints enabled the discovery of new inflammatory bowel disease (IBD) treatments. Herein, we describe efforts to advance the study of gastrointestinal (GI) manifestations in systemic sclerosis (SSc). RECENT FINDINGS: Insights into the scope of the problem, as well as advancements in the measurement and treatment of SSc-GI, are underway. Proposed SSc esophageal endophenotypes are now defined, risk stratification methods are growing, and imaging and functional studies are now employed to guide therapeutic interventions. Additional progress is being made in characterizing the gut microbiome in patients with SSc. Research into the role of the immune response in the pathogenesis of SSc-GI disease is also ongoing, evolving simultaneously with the development of methods to facilitate data collection with real-time capture of diet, exercise, and medication data. SUMMARY: Multidisciplinary teams are working to deepen our understanding of SSc-GI disease pathogenesis, to identify biomarkers for risk stratification and the assessment of disease activity, and to develop and validate outcomes and clinical trial endpoints to pave the way toward effective therapy for SSc-GI disease.

EULAR recommendations for the treatment of systemic sclerosis: 2023 update.

OBJECTIVES: To update the 2017 European Alliance of Associations for Rheumatology (EULAR) recommendations for treatment of systemic sclerosis (SSc), incorporating new evidence and therapies. METHODS: An international task force was convened in line with EULAR standard operating procedures. A nominal group technique exercise was performed in two rounds to define questions underpinning a subsequent systematic literature review. The evidence derived was discussed and overarching principles, recommendations and future research agenda were iteratively developed with voting rounds. RESULTS: The task force agreed on 22 recommendations covering 8 clinical/organ domains including Raynaud's phenomenon, digital ulcers, pulmonary arterial hypertension, scleroderma renal crisis, skin fibrosis, interstitial lung disease (ILD), gastrointestinal manifestations and arthritis. Most new recommendations are related to skin fibrosis and ILD. These included novel recommendations for the use of mycophenolate mofetil, nintedanib, rituximab and tocilizumab for the treatment of these crucial disease manifestations. The recommendations also included first-line and second-line interventions, providing increased utility for rheumatology practitioners. Important additions to the future research agenda included consideration of novel interventions for the management of vascular, musculoskeletal and gastrointestinal manifestations and calcinosis, as well as for the local management of digital ulcers. CONCLUSION: These updated recommendations include the first set of synthetic and biological targeted therapies recommended for key fibrotic manifestations of SSc as well as first-line combination treatment for newly diagnosed pulmonary artery hypertension and prioritise a new research agenda for the coming years.

Self-reported skin severity and quality of life in systemic sclerosis: multicentre validation of PASTUL.

OBJECTIVES: The aim of this study was to validate the Patient self-Assessment of Skin Thickness in Upper Limb questionnaire (PASTUL) in systemic sclerosis (SSc) and assess impact of skin involvement on health-related quality of life (HRQoL). METHODS: Participants were included in four UK centres. PASTUL specifies a grading of skin at 8 sites corresponding to the modified Rodnan Skin Score (mRSS). Construct validity was assessed by comparing PASTUL scores with mRSS. HRQoL was evaluated with EQ5D5L and Leeds SSc HRQoL questionnaires. Additionally, correlation between PASTUL and Scleroderma Skin Patient reported Outcome (SSPRO) was explored. Follow-up was 12 months. RESULTS: In total, 196 participants were included, mean age was 56.4 years (SD 13.9), 80.6% female (n = 158), mean disease duration 11.9 years (SD 9.9), 110 (56.1%) had limited cutaneous (lcSSc) and 81 (41.3%) diffuse cutaneous SSc (dcSSc). PASTUL and upper limb mRSS were well correlated at baseline, 6 and 12 months (ICC = 0.67, 0.78 and 0.62, p< 0.001). Test-retest reliability was good (ICC = 0.83, p< 0.001). There was a stronger correlation between PASTUL and upper limb mRSS in dcSSc compared with lcSSc (0.69 vs 0.51, p< 0.001). In participants with early disease (< 4 years) PASTUL was moderately correlated with HRQoL (r = 0.53, p< 0.001), correlations were weaker in the whole group. Mean time to do the PASTUL self-assessment was 5.0 min (SD 3.7). CONCLUSION: PASTUL is a feasible outcome tool that adds to assessments as SSPRO. Skin thickening is correlated with HRQoL, particularly in early disease.

Patients' unmet needs and treatment preferences concerning digital ulcers in systemic sclerosis.

INTRODUCTION: Digital ulcers (DUs) significantly impact on quality of life and function in patients with systemic sclerosis (SSc). The aim of our survey was to explore patients' perspectives and their unmet needs concerning SSc-DUs. MATERIALS: SSc patients were invited through international patient associations and social media to participate in an online survey. RESULTS: 358 responses were obtained from 34 countries: US (65.6%), UK (11.5%) and Canada (4.5%). Recurrent DUs are common: >10 DUs (46.1%), 5-10 DUs (21.5%), 1-5 DUs (28.5%), 1 DU (3.9%). Fingertip DUs were most frequent (84.9%), followed by those overlying the interphalangeal joints (50.8%). The impact of DUs in patients is broad, from broad-ranging emotional impacts to impact on activities of daily living, and personal relationships. Half (51.7%) of respondents reported that they received wound/ulcer care, most often provided by non-specialist wound care clinics (63.8%). There was significant variation in local (wound) DU care, in particular the use of debridement and pain management. DU-related education was only provided to one-third of patients. One-quarter (24.6%) were 'very satisfied' or 'satisfied' that the provided DU treatment(s) relieved their DU symptoms. Pain, limited hand function, and ulcer duration/chronicity were the main reasons for patients to consider changing DU treatment. CONCLUSIONS: Our data show that there is a large variation in DU treatment between countries. Patient access to specialist wound-care services is limited and only a small proportion of patients had their DU needs met. Moreover, patient education is often neglected. Evidence-based treatment pathways are urgently needed for DU management.

A phase 2 trial investigating the efficacy and safety of the mPGES-1 inhibitor vipoglanstat in systemic sclerosis-related Raynaud's.

OBJECTIVE: Our objective was to test the hypothesis, in a double-blind, placebo-controlled study that vipoglanstat, an inhibitor of microsomal prostaglandin E synthase-1 (mPGES-1) which decreases prostaglandin E2 (PGE2) and increases prostacyclin biosynthesis, improves RP. METHODS: Patients with systemic sclerosis (SSc) and ≥7 RP attacks during the last screening week prior to a baseline visit were randomised to four weeks treatment with vipoglanstat 120 mg or placebo. A daily electronic diary captured RP attacks (duration and pain) and Raynaud's Condition Score, with change in RP attacks/week as primary end point. Cold challenge assessments were performed at baseline and end of treatment. Exploratory endpoints included patients' and physicians' global impression of change, Assessment of Scleroderma-associated Raynaud's Phenomenon questionnaire, mPGES-1 activity, and urinary excretion of arachidonic acid metabolites. RESULTS: Sixty-nine subjects received vipoglanstat (n = 33) or placebo (n = 36). Mean weekly number of RP attacks (baseline; vipoglanstat 14.4[SD 6.7], placebo 18.2[12.6]) decreased by 3.4[95% CI -5.8;-1.0] and 4.2[-6.5;-2.0] attacks per week (p= 0.628) respectively. All patient reported outcomes improved, with no difference between the groups. Mean change in recovery of peripheral blood flow after cold challenge did not differ between the study groups. Vipoglanstat fully inhibited mPGES-1, resulting in 57% reduction of PGE2 and 50% increase of prostacyclin metabolites in urine. Vipoglanstat was safe and well tolerated. CONCLUSION: Although vipoglanstat was safe, and well tolerated in a dose achieving full inhibition of mPGES-1, it was ineffective in SSc-related RP. Further development and evaluation of vipoglanstat will therefore be in other diseases where mPGES-1 plays a pathogenetic role.

The 2024 British Society for Rheumatology guideline for management of systemic sclerosis-executive summary.

This guideline was developed according to the British Society for Rheumatology Guidelines Protocol by a Guideline Development Group comprising healthcare professionals with expertise in SSc and people with lived experience, as well as patient organization representatives. It is an update of the previous 2015 SSc guideline. The recommendations were developed and agreed by the group and are underpinned by published evidence, assessed by systematic literature review and reinforced by collective expert opinion of the group. It considers all aspects of SSc including general management, treatment of organ-based complications, including cardiopulmonary, renal and gastrointestinal tract manifestations, as well as broader impact of disease. Whilst it is focused on adults with SSc we expect that the guideline will be relevant to people of all ages and expert input and review by paediatric rheumatologists and other relevant specialists considered where the guideline was, or may not be, applicable to young people with SSc and juvenile-onset disease. In addition to providing guidance on disease assessment and management the full guideline also considers service organization within the National Health Service and future approaches to audit of the guideline. The lay summary that accompanies this abstract can be found in Supplemental information 1.

The 2024 British Society for Rheumatology guideline for management of systemic sclerosis.

This guideline was developed according to the British Society for Rheumatology Guidelines Protocol by a Guideline Development Group comprising healthcare professionals with expertise in SSc and people with lived experience, as well as patient organization representatives. It is an update of the previous 2015 SSc guideline. The recommendations were developed and agreed by the group and are underpinned by published evidence, assessed by systematic literature review and reinforced by collective expert opinion of the group. It considers all aspects of SSc including general management, treatment of organ-based complications, including cardiopulmonary, renal and gastrointestinal tract manifestations, as well as broader impact of disease. Whilst it is focused on adults with SSc we expect that the guideline will be relevant to people of all ages and expert input and review by paediatric rheumatologists and other relevant specialists considered where the guideline was, or may not be, applicable to young people with SSc and juvenile-onset disease. In addition to providing guidance on disease assessment and management the full guideline also considers service organization within the National Health Service and future approaches to audit of the guideline. The lay summary that accompanies this abstract can be found in Supplemental information 1.

Long-term retention rate, adverse event temporal patterns and rescue treatment strategies of mycophenolate mofetil in systemic sclerosis: insights from real-life.

BACKGROUND: Mycophenolate mofetil (MMF) is a mainstay for the treatment of systemic sclerosis (SSc). The occurrence and implications of MMF-related adverse events on drug retention rates in real life remain poorly defined. We aimed to determine the MMF retention rate and to investigate the causes and patterns of discontinuation, adverse events (AEs) and treatment options used after discontinuation. METHODS: SSc patients who started MMF treatment underwent a retrospective longitudinal assessment for up to 5 years. We documented the incidence, predictors, and impacts of MMF treatment on gastrointestinal intolerance, infections, laboratory abnormalities, and cancer. Rescue strategies implemented after MMF discontinuation were recorded. RESULTS: The 5-year MMF retention rate of 554 patients stood at 70.7% and 19.6% of them stopped MMF due to AEs. One out of every four patients experienced a dose reduction or discontinuation of MMF due to AEs, with gastrointestinal intolerance being the predominant cause. The 5-year cumulative incidence rates for gastrointestinal intolerance, cancer, severe infections, and laboratory toxicity leading to MMF discontinuation were 6.4%, 4.1%, 3.1%, and 2.1%, respectively. Lower respiratory tract was the most affected, with bacteria being the predominant causative agent. Intestinal and pulmonary circulation involvement were tied to elevated AE rates and MMF discontinuation. The most common approaches post-MMF cessation were "watch and wait" and switch to rituximab. CONCLUSIONS: MMF use in SSc appears to be limited by the occurrence of AEs, both in terms of persistence and dosing of the drug. Rescue options after MMF discontinuation are limited and many patients remain without immunosuppressant.

A randomised, parallel-group, double-blind, placebo-controlled phase 3 study to Determine the effectiveness of the type I interferon receptor antibody, Anifrolumab, In SYstemic sclerosis: DAISY study design and rationale.

OBJECTIVES: The type I interferon pathway is a promising target for treatment of patients with systemic sclerosis (SSc). Here, we describe the design of a multinational, randomised phase 3 study to Determine the effectiveness of the type I interferon receptor antibody, Anifrolumab, In SYstemic sclerosis (DAISY). METHODS: DAISY includes a 52-week double-blind, placebo-controlled treatment period, a 52-week open-label active treatment period, and a 12-week safety follow-up period. The patient population includes a planned 306 adults with limited or diffuse cutaneous active SSc who satisfied American College of Rheumatology/European Alliance of Associations for Rheumatology 2013 SSc criteria. Use of standard immunosuppressants, including mycophenolate mofetil, at a stable dose prior to randomisation is permitted in addition to weekly subcutaneous anifrolumab or placebo. Efficacy will be assessed at Week 52 via Revised-Composite Response Index in SSc (CRISS)-25 response (primary endpoint). Lung function and skin thickness will be assessed via change from baseline in forced vital capacity in patients with SSc-associated interstitial lung disease and modified Rodnan Skin Score, respectively (key secondary endpoints). CONCLUSIONS: The DAISY trial will evaluate the efficacy and safety of anifrolumab as a first-in-class treatment option for patients with both limited and diffuse cutaneous SSc and will provide insight into the contributions of type I interferon to SSc pathogenesis. Revised-CRISS-25 can account for improvement and worsening in a broad set of validated clinical measures beyond lung function and skin thickness, including clinician- and patient-reported outcomes, capturing the heterogeneity of SSc.

Systemic sclerosis is a chronic autoimmune disease that leads to inflammation and scarring of the skin and internal organs, especially the lungs. Systemic sclerosis and lupus are both associated with increased interferon signalling, which is usually triggered by viral infections, but is related to damaging inflammation in these diseases. Anifrolumab, a drug that blocks interferon signalling, is already used to treat patients with lupus (also known as SLE), so it could potentially be used to treat patients with systemic sclerosis. This publication details the DAISY study design and explains why it is needed. This study will follow 2 groups of 153 patients with systemic sclerosis over 2 years. During the first year, in addition to any standard immunosuppressant therapy, the groups will receive weekly injections of either anifrolumab or "dummy drug" (placebo). In the second year, all patients will receive anifrolumab with their standard immunosuppressant therapy. Multiple factors will be considered to evaluate the efficacy of anifrolumab treatment, including clinical measurements of skin thickness and lung function, and questionnaires completed by clinicians and patients to report on patient health and their everyday function during treatment. The DAISY study will investigate the efficacy and safety of anifrolumab treatment in a diverse group of patients with systemic sclerosis who currently have limited options for effective treatment. The study will evaluate the impact of anifrolumab treatment on multiple aspects of the disease, and how patients feel about their overall health-related quality of life.

Fibroblast expression of CD248 may contribute to exacerbation of microvascular damage during systemic sclerosis.

OBJECTIVES: CD248 is a glycoprotein, highly expressed on pericytes and fibroblasts (FBs), that is implicated in the fibrotic process. During angiogenesis, CD248 can promote vessel regression, binding multimerin-2 (MMRN-2). Thus, we investigated the expression of MMRN-2 in systemic sclerosis (SSc)-skin and of CD248 in isolated SSc-FBs. The anti-angiogenic property of CD248+ SSc-FBs was evaluated by co-culturing these cells with healthy control endothelial cells (HC-ECs). The apoptotic effect of CD248 on HC-ECs was evaluated. Finally, the ability of CD248 to prevent activation of VEGF receptor 2 (VEGFR2) was assessed. METHODS: By IF, MMRN-2 was investigated in SSc-skin and CD248 in SSc FBs. The anti-angiogenic property of CD248+ SSc-FBs was evaluated by HC-ECs/SSc-FBs co-cultures. Lentiviral-induced CD248 short-hairpin RNA delivery was employed for loss-of-function studies in SSc-FBs. HC-ECs were cultured in the presence of CD248 to assess apoptosis by IF and VEGFR2 phosphorylation by western blot. RESULTS: MMRN-2 expression was increased in skin SSc-ECs, whereas CD248 expression was increased in SSc-FBs. Functionally, CD248+-SSc-FBs suppressed angiogenesis in the organotypic model, as assessed by the reduction in total tube length of HC-ECs. This anti-angiogenetic behaviour was reversed by CD248 silencing. Furthermore, the presence of CD248 promoted the apoptosis of HC-ECs. Finally, CD248 prevented activation of VEGFR2 by reducing its phosphorylation after VEGF stimulation. CONCLUSION: CD248 was anti-angiogenic in vitro due to a reduction in tube formation and to induction of apoptosis of ECs. Increased expression of CD248 in SSc could contribute to the microvascular rarefaction observed at the tissue level in SSc. Our results suggest a pathogenic role for CD248-MMRN-2 in SSc.

A Phase II randomized controlled trial of oral prednisolone in early diffuse cutaneous systemic sclerosis (PRedSS).

OBJECTIVES: Although the painful and disabling features of early diffuse cutaneous SSc (dcSSc) have an inflammatory basis and could respond to corticosteroids, corticosteroids are a risk factor for scleroderma renal crisis. Whether or not they should be prescribed is therefore highly contentious. Our aim was to examine safety and efficacy of moderate-dose prednisolone in early dcSSc. METHODS: PRedSS set out as a Phase II, multicentre, double-blind randomized controlled trial, converted to open-label during the Covid-19 pandemic. Patients were randomized to receive either prednisolone (∼0.3 mg/kg) or matching placebo (or no treatment during open-label) for 6 months. Co-primary endpoints were the HAQ Disability Index (HAQ-DI) and modified Rodnan skin score (mRSS) at 3 months. Over 20 secondary endpoints included patient reported outcome measures reflecting pain, itch, fatigue, anxiety and depression, and helplessness. Target recruitment was 72 patients. RESULTS: Thirty-five patients were randomized (17 prednisolone, 18 placebo/control). The adjusted mean difference between treatment groups at 3 months in HAQ-DI score was -0.10 (97.5% CI: -0.29, 0.10), P = 0.254, and in mRSS -3.90 (97.5% CI: -8.83, 1.03), P = 0.070, both favouring prednisolone but not significantly. Patients in the prednisolone group experienced significantly less pain (P = 0.027), anxiety (P = 0.018) and helplessness (P = 0.040) than control patients at 3 months. There were no renal crises, but sample size was small. CONCLUSION: PRedSS was terminated early primarily due to the Covid-19 pandemic, and so was underpowered. Therefore, interpretation must be cautious and results considered inconclusive, indicating the need for a further randomized trial. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT03708718.

Insights into molecular and clinical characteristics of very early systemic sclerosis.

PURPOSE OF REVIEW: The early heterogenous presentation of systemic sclerosis (SSc), in particular without skin involvement, has been a confounding factor delaying early diagnosis. In fact, early signs of SSc as Raynaud's phenomenon and puffy fingers, are also typical of other connective tissue diseases (CTDs) such as mixed CTD and undifferentiated CTD. In the last decade, a significant effort has been dedicated in defining molecular characteristics that could be used as early SSc biomarkers. In this narrative review, we address the present situation where several clinical scenarios are in search of a correct positioning into the prescleroderma (pre-SSc) phase as well as in the very early phase of SSc. RECENT FINDINGS: Literature data showed that a part of patients classified as sine scleroderma SSc (ssSSc), mixed CTD and undifferentiated CTD may already belong to the very early phase of SSc, thus having a different pattern of progression to SSc. Recently, the very early diagnosis of systemic sclerosis (VEDOSS) criteria has been validated. SUMMARY: while the area of pre-SSc still remains fuzzy, the VEDOSS study has shown that a 'window of opportunity' does exist also for SSc. In the very next future, this may allow to start the treatment to prevent the disease progression to a more advanced fibrotic stage.

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.

First pilot study of extracellular volume MRI measurement in peripheral muscle of systemic sclerosis patients suggests diffuse fibrosis.

OBJECTIVES: Peripheral muscle involvement in SSc may comprise myositis or a non-inflammatory myopathy. There is little understanding of the nature of SSc myopathy. This pilot study aimed to evaluate the presence of diffuse fibrosis in the peripheral muscle of patients with SSc by determining extracellular volume (ECV) MRI measurement. METHODS: SSc patients, with either suspected myopathy or no muscle involvement, and healthy controls (HCs) had native T1 and ECV MRI quantification of the thigh and creatine-kinase (CK) measured. Suspected myopathy was defined as current / history of minimally raised CK (>320; <600 IU/l) ± presence of clinical signs/symptoms (including proximal lower-limb muscle weakness and/or myalgia) ± a Manual Muscle Testing (MMT) 8 score of <5 in the thighs. RESULTS: Twelve SSc patients and 10 HCs were recruited. Of the 12 patients, 9 had limited cutaneous SSc, 4 had interstitial lung disease, and 7 had suspected myopathy. The higher skeletal muscle ECV was recorded for SSc patients compared with HCs [mean (s.d.) 23 (11)%, vs 11 (4)%, P = 0.04]. Peripheral muscle ECV was associated with CK (rho = 0.554, P = 0.061) and was higher in SSc patients with myopathy than in those with no myopathy [mean (s.d.) 28 (10) vs 15 (5), P = 0.023]. It was determined that an ECV of 22% best identified myopathy (with a sensitivity of 71% and a specificity of 80%). CONCLUSION: This hypothesis-generating study showed higher ECV in SSc patients compared with HCs, as well as association of ECV with suspected myopathy, suggesting the presence of diffuse fibrosis in the peripheral muscle of SSc patients. Further studies are needed to understand the nature of SSc myopathy.

Biological and clinical insights from a randomized phase 2 study of an anti-oncostatin M monoclonal antibody in systemic sclerosis.

OBJECTIVES: The cytokine oncostatin M (OSM) is implicated in the pathology of SSc. Inhibiting OSM signalling using GSK2330811 (an anti-OSM monoclonal antibody) in patients with SSc has the potential to slow or stop the disease process. METHODS: This multicentre, randomized, double-blind, placebo-controlled study enrolled participants ≥18 years of age with active dcSSc. Participants were randomized 3:1 (GSK2330811:placebo) in one of two sequential cohorts to receive GSK2330811 (cohort 1: 100 mg; cohort 2: 300 mg) or placebo s.c. every other week for 12 weeks. The primary endpoint was safety; blood and skin biopsy samples were collected to explore mechanistic effects on inflammation and fibrosis. Clinical efficacy was an exploratory endpoint. RESULTS: Thirty-five participants were randomized to placebo (n = 8), GSK2330811 100 mg (n = 3) or GSK2330811 300 mg (n = 24). Proof of mechanism, measured by coordinate effects on biomarkers of inflammation or fibrosis, was not demonstrated following GSK2330811 treatment. There were no meaningful differences between GSK2330811 and placebo for any efficacy endpoints. The safety and tolerability of GSK2330811 were not favourable in the 300 mg group, with on-target, dose-dependent adverse events related to decreases in haemoglobin and platelet count that were not observed in the 100 mg or placebo groups. CONCLUSION: Despite a robust and novel experimental medicine approach and evidence of target engagement, anticipated SSc-related biologic effects of GSK2330811 were not different from placebo and safety was unfavourable, suggesting OSM inhibition may not be a useful therapeutic strategy in SSc. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov, NCT03041025; EudraCT, 2016-003417-95.

Targeting human plasmacytoid dendritic cells through BDCA2 prevents skin inflammation and fibrosis in a novel xenotransplant mouse model of scleroderma.

OBJECTIVES: Plasmacytoid dendritic cells (pDC) have been implicated in the pathogenesis of autoimmune diseases, such as scleroderma (SSc). However, this has been derived from indirect evidence using ex vivo human samples or mouse pDC in vivo. We have developed human-specific pDC models to directly identify their role in inflammation and fibrosis, as well as attenuation of pDC function with BDCA2-targeting to determine its therapeutic application. METHODS: RNAseq of human pDC with TLR9 agonist ODN2216 and humanised monoclonal BDCA2 antibody, CBS004. Organotypic skin rafts consisting of fibroblasts and keratinocytes were stimulated with supernatant from TLR9-stimulated pDC and with CBS004. Human pDC were xenotransplanted into Nonobese diabetic/severe combined immunodeficiency (NOD SCID) mice treated with Aldara (inflammatory model), or bleomycin (fibrotic model) with CBS004 or human IgG control. Skin punch biopsies were used to assess gene and protein expression. RESULTS: RNAseq shows TLR9-induced activation of human pDC goes beyond type I interferon (IFN) secretion, which is functionally inactivated by BDCA2-targeting. Consistent with these findings, we show that BDCA2-targeting of pDC can completely suppress in vitro skin IFN-induced response. Most importantly, xenotransplantation of human pDC significantly increased in vivo skin IFN-induced response to TLR agonist and strongly enhanced fibrotic and immune response to bleomycin compared with controls. In these contexts, BDCA2-targeting suppressed human pDC-specific pathological responses. CONCLUSIONS: Our data indicate that human pDC play a key role in inflammation and immune-driven skin fibrosis, which can be effectively blocked by BDCA2-targeting, providing direct evidence supporting the development of attenuation of pDC function as a therapeutic application for SSc.

The intracellular chloride channel 4 (CLIC4) activates systemic sclerosis fibroblasts.

OBJECTIVES: Tissue fibrosis in SSc is driven by active fibroblasts (myofibroblasts). Previous studies have shown the intracellular chloride channel 4 (CLIC4) mediates the activation of cancer-associated fibroblasts. In this study we investigated the role of CLIC4 in SSc fibroblast activation. METHODS: Fibroblasts were obtained from full thickness skin biopsies from SSc patients (early-diffuse). RNA and protein were collected from the fibroblasts and CLIC4 transcript and protein levels were assessed by qPCR and western blot. SSc patient fibroblasts were treated with the chloride channel inhibitors nitro-2-(3-phenylpropylamino)benzoic acid and indyanyloxyacetic acid 94. RESULTS: CLIC4 was expressed at significantly higher levels in SSc patients' fibroblasts compared with healthy controls, at both the transcript (3.7-fold) and protein (1.7-fold) levels. Inhibition of the TGF-ß receptor and its downstream transcription factor SMAD3 led to a reduction in CLIC4 expression, confirming this pathway as the main driver of CLIC4 expression. Importantly, treatment of SSc fibroblasts with known pharmacological inhibitors of CLIC4 led to reduced expression of the myofibroblast markers collagen type 1 and α-smooth muscle actin, inferring a direct role for CLIC4 in disease pathogenesis. CONCLUSIONS: We have identified a novel role for CLIC4 in SSc myofibroblast activation, which strengthens the similarities of SSc fibroblasts with cancer-associated fibroblasts and highlights this channel as a novel target for therapeutic intervention.