Flemish network on rare connective tissue diseases (CTD): patient pathways in systemic sclerosis. First steps taken

Despite the low prevalence of each rare disease, the total burden is high. Patients with rare diseases encounter numerous barriers, including delayed diagnosis and limited access to high-quality treatments. In order to tackle these challenges, the European Commission launched the European Reference Networks (ERNs), cross-border networks of healthcare providers and patients representatives. In parallel, the aims and structure of these ERNs were translated at the federal and regional levels, resulting in the creation of the Flemish Network of Rare Diseases. In line with the mission of the ERNs and to ensure equal access to care, we describe as first patient pathways for systemic sclerosis (SSc), as a pilot model for other rare connective and musculoskeletal diseases. Consensus was reached on following key messages: 1. Patients with SSc should have multidisciplinary clinical and investigational evaluations in a tertiary reference expert centre at baseline, and subsequently every three to 5 years. Intermediately, a yearly clinical evaluation should be provided in the reference centre, whilst SSc technical evaluations are permissionably executed in a centre that follows SSc-specific clinical practice guidelines. In between, monitoring can take place in secondary care units, under the condition that qualitative examinations and care including interactive multidisciplinary consultations can be provided. 2. Patients with early diffuse cutaneous SSc, (progressive) interstitial lung disease and/or pulmonary arterial hypertension should undergo regular evaluations in specialised tertiary care reference institutions. 3. Monitoring of patients with progressive interstitial lung disease and/or pulmonary (arterial) hypertension will be done in agreement with experts of ERN LUNG.

POS0914 LATE SKIN FIBROSIS IN SYSTEMIC SCLEROSIS: A STUDY FROM THE EUSTAR COHORT

Background

Skin fibrosis is a cardinal feature of systemic sclerosis (SSc) and associated with significant disability. The early trajectory of skin fibrosis provides insights into the course of the disease including mortality; however, little is known about late skin fibrosis in SSc.

Objectives

The aims of our study were to ascertain the prevalence and characteristics of late skin fibrosis in SSc.

Methods

We developed and tested three conceptual scenarios of late (>5 years after 1st non-RP sign or symptom) skin fibrosis (Figure 1):

Figure 1.

Conceptual models/scenarios of late skin fibrosis in SSc. A: worsening and then improvement (>3 mRSS) during the first 5 years, and then worsened again after 5 years. B: worsening for the first time after 5 years. C: worsening in the first 5 years and stayed high after 5 years (i.e., failure to improve).

A. Worsening and then improvement (>3 mRSS) during the first 5 years, and then worsened again after 5 years.

B. Worsening for the first time after 5 years.

C. Worsening in the first 5 years and stayed high after 5 years (i.e., failure to improve).

We defined skin worsening as modified Rodnan skin score (mRSS) ≥ 5 units or ≥ 25%. Using strict inclusion criteria including complete mRSS, we identified 1,043 (out of 19,115) patients within the EUSTAR database for our analysis. We further restricted analysis within 887 (out of 1,043) patients who had limited (lcSSc) or diffuse cutaneous SSc (dcSSc) at baseline.

Results

One-fifth of patients among the whole cohort (n=208/1043, 19.9%) including in patients with lcSSc or dcSSc at baseline (n=193/887, 21.8%) developed late skin fibrosis. This was largely due to new skin worsening or failure to improve. Patients with lower baseline mRSS and lcSSc were more likely to develop late skin fibrosis. Anti-Scl-70 antibodies (Table 1) were associated with progression from baseline lcSSc to dcSSc, and anticentromere antibodies were protective.

Table 1.

Impact of autoantibody status on progression from baseline limited to diffuse cutaneous SSc (dcSSc).

Skin worsening after 5 years (Scenario B) (n=70)Skin worsening within 5 years and failed to improve after 5-year window (Scenario C) (n=61)Progressed to dcSSc (n=23)Not progressed to dcSSc(n=47)P-valueProgressed to dcSSc (n=37)Not progressed to dcSSc(n=24)P-valueAnticentromere+ve2/22 (9.1%)19/42 (45.2%)0.00346/34 (17.6%)14/21 (66.7%)0.0002-ve20/22 (90.9%)23/42 (54.8%)28/34 (82.4%)7/21 (33.3%)Anti-Scl-70+ve15/23 (65.2%)14/44 (31.8%)0.008822/36 (61.1%)8/23 (34.8%)0.0485-ve8/23 (34.8%)30/44 (68.2%)14/36 (38.9%)15/23 (65.2%)Anti-RNA-Polymerase-III+ve0/12 (0.0%)1/22 (4.5%)1.00000/6 (0.0%)0/14 (0.0%)---ve12/12 (100%)21/22 (95.5%)6/6 (100%)14/14 (100%)

Conclusion

Late skin fibrosis affects approximately 20% of SSc patients >5 years after onset of disease. We have identified different patterns relevant to clinical practice and trial design. Late skin fibrosis is usually due to new worsening or failure of skin to improve. Progression from baseline limited to diffuse cutaneous SSc was associated with anti-Scl-70 antibodies, and anticentromere antibodies were protective. Late skin fibrosis is a neglected manifestation of SSc and warrants further investigation including to determine clinical outcomes and optimal therapeutic strategy.

Acknowledgements

On behalf of EUSTAR collaborators.

Disclosure of Interests

Michael Hughes Speakers bureau: Speaking fees from Actelion pharmaceuticals, Eli Lilly, and Pfizer, outside of the submitted work, Suiyuan Huang: None declared, Juan Jose Alegre Sancho Speakers bureau: Speaking and/or investigational fees from Actelion pharmaceuticals, Eli Lilly, Pfizer, Boehringer Ingelheim, Roche, and GSK, outside of the submitted work, Grant/research support from: Speaking and/or investigational fees from Actelion pharmaceuticals, Eli Lilly, Pfizer, Boehringer Ingelheim, Roche, and GSK, outside of the submitted work, Patricia Carreira: None declared, Merete Engelhart: None declared, Eric Hachulla Speakers bureau: Received consulting fees/meeting fees from Johnson & Johnson, Boehringer Ingelheim, Bayer, GSK, Roche-Chugai, Sanofi-Genzyme; speaking fees from Johnson & Johnson, GSK, Roche-Chugai; and research funding from CSL Behring, GSK, Roche-Chugai and Johnson & Johnson., Consultant of: Received consulting fees/meeting fees from Johnson & Johnson, Boehringer Ingelheim, Bayer, GSK, Roche-Chugai, Sanofi-Genzyme; speaking fees from Johnson & Johnson, GSK, Roche-Chugai; and research funding from CSL Behring, GSK, Roche-Chugai and Johnson & Johnson., Jörg Henes Speakers bureau: Lectures for CHUGAI, Boehringer-Ingelheim, Eduardo Kerzberg: None declared, Maria Rosa Pozzi: None declared, Gabriela Riemekasten: None declared, Vanessa Smith: None declared, Gabriella Szucs: None declared, Marie Vanthuyne: None declared, Elisabetta Zanatta: None declared, Oliver Distler: None declared, Armando Gabrielli: None declared, Anna-Maria Hoffmann-Vold: None declared, Viginia Steen: None declared, Dinesh Khanna Shareholder of: DK has stock options in Eicos Sciences, Inc., Consultant of: Consultant for Acceleron, Amgen, Boehringer Ingelheim, CSL Behring, Chemomab, Genentech/Roche, Horizon, Mitsubishi Tanabe Pharma, Prometheus, Talaris., Grant/research support from: Has received grants from Bayer, BMS, Horizon and Pfizer (to University of Michigan).

OP0309 WES ANALYSIS OF RARE FAMILIES POINTS TO A PATHOGENIC ROLE FOR THE cGAS/STING-TYPE I IFN AXIS IN SSc

Background

Systemic sclerosis (SSc) is a rare (prevalence ±20/100,000), chronic condition characterized by vascular, immunological and connective tissue abnormalities. Genetic factors contribute to disease, as evidenced by a 15-fold increased relative risk in relatives of patients. Case-control studies have identified numerous associated loci; the identification and functional validation of risk alleles has however been elusive. No monogenic or oligogenic causes of SSc have been demonstrated, likely due to the infrequency of familial clustering (≤ 1.6% of cases) in this disease. We are fortunate to have access to DNA samples from five such families, with two affected first-degree relatives each: To our knowledge the only series of its kind.

Objectives

The goal of our research is to identify and functionally validate genes that drive SSc pathogenesis in these families, thereby shedding light on fundamental disease mechanisms. In light of the apparent lack of a multi-generational effect, we hypothesize that SSc may be transmitted as a di/oligogenic trait in these families, with two-to-a-few genes acting together to cause disease.

Methods

Whole exome sequencing (WES) was performed on all available blood-DNA (Figure 1). We filtered for variants that are (a) shared by both affected individuals within each family, (b) absent-to-rare in the general population, and (c) predicted to affect protein function by multiple in silico tools. Candidate gene prioritization and pathway analysis is followed by in vitro testing of a subset of SSc-variants, to assess for their effects on protein function. Where two strong candidate genes are identified in the same family, in vitro validation of both variants will be followed by the generation of single- vs. double- knock-in mice, to test for di/oligogenic effects of variant combinations on SSc-related phenotypes.

Figure 1.

SSc families. Filled symbols: affected. Arrows: WES on blood-DNA. lSSc: Limited SSc; lcSSc: Limited cutaneous SSc; dcSSC: Diffuse cutaneous SSc. cGAS/STING (red) and IFN I (black) - related candidate genes.

Results

WES yielded 23-45 genes per family with variants that satisfied the above criteria. Prioritization of candidates was based on systematic annotation of all 180 genes for expression pattern, function, and potential impact of the SSc-variants. Our data suggest familial SSc is genetically heterogeneous, with little sharing of candidates between families. We therefore assessed for pathways represented in gene-lists from multiple families, and found that participants in the cGAS/STING - type I-IFN axis are identified in all (Figure 1). This would suggest a unifying disease mechanism.

cGAS/STING is a sentinel system responsible for the production of anti-viral type I interferons (IFN-α/β) and pro-inflammatory cytokines in the presence of cytoplasmic double stranded DNA (dsDNA). cGAS/STING-dependent self-dsDNA sensing has been implicated in silica-induced inflammation: a risk factor in SSc and pulmonary fibrosis. A type I IFN-response signature is identified in SSc patients and correlates with disease severity. Mutations in two of our candidates cause Mendelian diseases with phenotypic overlaps with SSc, and all but one cause disease-relevant phenotypes when perturbed in mice. Finally, preliminary in vitro data suggest gain-of-function effects of the variant identified in TMEM173/STING, and loss-of-function effects in NT5E/CD73 and PRKD2 (the last with two different variants identified in two families; Figure 1). All would lead to increased IFN-I signaling.

Conclusion

We report, for the first time, WES analysis of a familial SSc series of unprecedented size for this rare disease. The identification of potential “driver” gene variants in cGAS/STING-type I IFN signaling regulators across all families points to an important pathogenic role for this pathway in SSc.

Disclosure of Interests

Pierre Maus: None declared, Vanessa Smith: None declared, Tessa Du Four: None declared, Marie Vanthuyne: None declared, Bernard Lauwerys Shareholder of: UCB Pharma, Employee of: Currently an employee of UCB Pharma, Nisha Limaye: None declared

Analysis of the influence of PTPN22 gene polymorphisms in systemic sclerosis

OBJECTIVE

Two functional single nucleotide polymorphisms (SNP) in the PTPN22 gene (rs24746601 and rs33996649) have been associated with autoimmunity. The aim of this study was to investigate the role of the R263Q SNP for the first time and to re-evaluate the role of the R620W SNP in the genetic predisposition to systemic sclerosis (SSc) susceptibility and clinical phenotypes.

METHODS

3422 SSc patients (2020 with limited cutaneous SSc and 1208 with diffuse cutaneous SSc) and 3638 healthy controls of Caucasian ancestry from an initial case--control set of Spain and seven additional independent replication cohorts were included in our study. Both rs33996649 and rs2476601 PTPN22 polymorphisms were genotyped by TaqMan allelic discrimination assay. A meta-analysis was performed to test the overall effect of these PTPN22 polymorphisms in SSc.

RESULTS

The meta-analysis revealed evidence of association of the rs2476601 T allele with SSc susceptibility (p(FDRcorrected)=0.03 pooled, OR 1.15, 95% CI 1.03 to 1.28). In addition, the rs2476601 T allele was significantly associated with anticentromere-positive status (p(FDRcorrected)=0.02 pooled, OR 1.22, 95% CI 1.05 to 1.42). Although the rs33996649 A allele was significantly associated with SSc in the Spanish population (p(FDRcorrected)=0.04, OR 0.58, 95% CI 0.36 to 0.92), this association was not confirmed in the meta-analysis (p=0.36 pooled, OR 0.89, 95% CI 0.72 to 1.1).

CONCLUSION

The study suggests that the PTPN22 R620W polymorphism influences SSc genetic susceptibility but the novel R263Q genetic variant does not. These data strengthen evidence that the R620W mutation is a common risk factor in autoimmune diseases.

A pilot study of mycophenolate mofetil combined to intravenous methylprednisolone pulses and oral low-dose glucocorticoids in severe early systemic sclerosis

OBJECTIVE

This pilot study was aimed at evaluating the efficacy and safety of a protocol-based treatment strategy combining mycophenolate mofetil (MMF), intravenous (IV) methylprednisolone (MP) pulses and low-dose glucocorticoids (GC) in early systemic sclerosis (SSc) patients suffering from either active interstitial lung disease (ILD) or extensive skin disease.

PATIENTS AND METHODS

Sixteen SSc patients were recruited in the study, 9 based on the severity of their skin involvement (modified Rodnan total skin score [TSS] >or= 15) and 7 based on the presence of active ILD. Patients received 3 consecutive daily IV MP pulses, followed by 5 additional monthly IV MP pulses. MMF (0.5 g bid for one week; then, 1 g bid) and low-dose (5-10 mg/day) oral prednisolone were prescribed for one year. Patients were assessed at baseline, month 6 and 12. Statistics were by ANOVA.

RESULTS

TSS and Health Assessment Questionnaire significantly improved over time. In ILD patients, the vital capacity, forced expiratory volume in one second and carbon monoxide diffusing capacity significantly improved. Although the difference was not statistically significant, ground glass lesions decreased, based on semi-quantitative planimetry analyses performed on chest high-resolution computerized tomography. Toxicity was low and none of the patients suffered from renal crisis.

CONCLUSION

The results of this pilot study suggest that the combination of MMF, IV MP and low-dose GC might achieve good clinical, functional and radiological results in patients suffering from severe early SSc.

Metal partitioning in a sulfidic canal sediment: metal solubility as a function of pH combined with EDTA extraction in anoxic conditions

The chemical forms of low concentrations of metals (Zn, Pb, Cu, Cd, Co and Mn) and main components (Fe and Ca) were determined under the original reducing conditions of a sulfide-rich sediment from the Gent-Terneuzen Canal (Belgium). Therefore, dissolution experiments as a function of pH were made in a salt solution mimicking the canal water. The centrifugates remaining after the dissolution vs. pH experiments were subsequently further extracted with 0.1 M EDTA/0.5 M NaAc (pH 4.65) to determine eventually readsorbed and/or reprecipitated metal ions. The experimental dissolution vs. pH edge of calcium, iron, manganese and cobalt had a lower slope than theoretically expected on the basis of the solubility of, respectively, calcium carbonate, iron sulfide/iron carbonate, manganese sulfide/manganese carbonate and cobalt sulfide and was explained by the combination of (a) the solubilities of the various minerals and (b) metal readsorption onto clay minerals and organic matter. Higher metal recoveries were measured in the 0.1 M EDTA/0.5 M NaAc mixture and proved that in addition coprecipitate formation with iron sulfide/iron carbonate minerals may occur. The solubility of zinc, lead, cadmium and copper was very low in the mimicking salt solution even at very low pH values (up to pH 1) in agreement with the theoretical solubility of their discrete metal sulfides. However, by using an additional 0.1 M EDTA/0.5 M NaAc extraction on the centrifugates remaining after the dissolution vs. pH experiments, it was qualitatively shown that zinc and lead were partly associated with iron sulfide/iron carbonate phases in the real sediment (in addition to their presence in discrete metal sulfides). Cadmium was present solely in discrete cadmium sulfide phases. It was not possible to verify whether copper was present in discrete copper sulfide phases and/or in mixed coprecipitates with iron sulfide/iron carbonate minerals.