Late skin fibrosis in systemic sclerosis: a study from the EUSTAR cohort.

OBJECTIVES: The early trajectory of skin fibrosis provides insights into the disease course of systemic sclerosis (SSc) including mortality; however, little is known about late skin fibrosis. 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 first non-RP feature) skin fibrosis including new worsening of skin disease, and failure to improve after worsening within 5-year window. We defined skin worsening as change in 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 1043) patients who had lcSSc or dcSSc at baseline. RESULTS: One-fifth of patients among the whole cohort (n = 208/1043, 19.9%) experienced mRSS worsening, including in patients with lcSSc or dcSSc at baseline (n = 193/887, 21.8%). This was largely due to new skin worsening after the 5-year window or failure to improve with worsening within the 5-year window. Patients with lower baseline mRSS and lcSSc were more likely to develop late skin fibrosis. Anti-Scl-70 was associated with progression from baseline lcSSc to dcSSc, and anticentromere was protective. CONCLUSIONS: Late skin fibrosis is not uncommon in SSc. We have identified different patterns relevant to clinical practice and trial design. Late skin fibrosis is a neglected manifestation of SSc and warrants further investigation including to determine clinical outcomes and optimal therapeutic strategy.

Sex influence on outcomes of patients with systemic sclerosis-associated interstitial lung disease: a EUSTAR database analysis.

OBJECTIVE: Interstitial lung disease (ILD) is the leading cause of morbidity and mortality in systemic sclerosis (SSc) patients. We aimed to investigate the impact of sex on SSc-ILD. METHODS: EUSTAR SSc patients with radiologically confirmed ILD and available percentage predicted forced vital capacity (%pFVC) were included. Demographics and disease features were recorded. A change in %pFVC over 12 months (s.d. 6) (cohort 1) was classified into stable (≤4%), mild (5-9%) and large progression (≥10%). In those with 2-year longitudinal %pFVC (cohort 2), the %pFVC change at each 12-month (s.d. 6) interval was calculated. Logistic regression analyses [odds ratio (OR) and 95% CI] and Cox proportional hazards models adjusted for age and %pFVC were applied. RESULTS: A total of 1136 male and 5253 female SSc-ILD patients were identified. Males were significantly younger, had a shorter disease duration, had a higher prevalence of CRP elevation and frequently had diffuse cutaneous involvement. In cohort 1 (1655 females and 390 males), a higher percentage of males had stable ILD (74.4% vs 69.4%, P = 0.056). In multivariable analysis, disease duration and %pFVC [OR 0.99 (95% CI 0.98, 0.99) and OR 0.97 (95% CI 0.95, 0.99), respectively] in males and age, %pFVC and anti-centromere [OR 1.02 (95% CI 1.00, 1.04), OR 0.97 (95% CI 0.96, 0.98) and OR 0.39 (95% CI 0.245, 0.63), respectively] in females were associated with large progression. The 1-year mortality rate was higher in males (5.1% vs 2.5%, P = 0.013). In cohort 2 (849 females and 209 males), a higher percentage of females showed periods of large progression (11.7% vs 7.7%, P = 0.023), the percentage of patients with none, one or two periods of worsening was not different. The overall death rate was 30.9% for males and 20.4% in females (P < 0.001). In the survival analysis, male sex was a predictor of mortality [OR 1.95 (95% CI 1.66, 2.28)]. CONCLUSIONS: Male SSc-ILD patients have a poorer prognosis and sex-specific predictors exist in SSc-ILD.

Comparison of the disease activity score and the revised EUSTAR activity index in diffuse cutaneous systemic sclerosis patients.

OBJECTIVES: To compare the ability of the Disease Activity Score (DAS) and the Revised EUSTAR Activity Index (RAI) to detect diffuse cutaneous systemic sclerosis (dcSSc) patients requiring treatment intensification in a Belgian cohort. METHODS: We retrospectively compared the widely used DAS and the recently developed RAI in a longitudinal cohort (median follow-up of 42 months) of 62 dcSSc patients, of whom 30 with a disease duration ≤3 years at inclusion. Active disease was defined by a DAS ≥3/10 or a RAI ≥2.5/10. We chose a pragmatic definition to assess disease progression, namely any start or increase of glucocorticoids, immunosuppressants, anti-endothelin receptors or prostanoids. Sensitivity, specificity, negative and positive predictive values (NPV and PPV) of DAS and RAI for prediction of actual treatment changes were compared by ROC curves. RESULTS: According to RAI, 48% (of all dcSSc patients) and 55% (of ≤3 years dcSSc patients) were categorised as effectively active during follow-up while 34% and 43% according to DAS, respectively. The PPV and the NPV to detect disease progression, in ≤3 years dcSSc patients, were 59% and 89% for RAI vs 73% and 87% for DAS, respectively. The area under ROC curves were high for both scores (0.85 for RAI and 0.87 for DAS). CONCLUSIONS: Both scores are proven as predictive to detect disease activity, with a slightly better sensitivity for RAI. By contrast, RAI lacks specificity in predicting a real need for treatment intensification, thereby possibly leading to overtreatment.

Hypercalcemia Heralding Pneumocystis jirovecii Pneumonia in an HIV-Seronegative Patient with Diffuse Cutaneous Systemic Sclerosis.

Pneumocystis pneumonia (PCP) is a life-threatening fungal infection occurring in immunocompromised patients such as HIV-positive patients with low CD4 cell count or patients under heavy immunosuppressive therapy. We report the case of a 59-year-old male with severe diffuse cutaneous systemic sclerosis presenting with asthenia, dry cough and worsening shortness of breath for the last 15 days. Biological studies were remarkable for PTH-independent severe hypercalcemia with low 25-hydroxyvitamin D and a paradoxically elevated 1,25-dihydroxyvitamin D. Early bronchoalveolar lavage allowed for PCP diagnosis and targeted treatment. We discuss the underlying physiopathology and difficulties regarding prophylaxis and treatment.

Identification of novel genetic markers associated with clinical phenotypes of systemic sclerosis through a genome-wide association strategy.

The aim of this study was to determine, through a genome-wide association study (GWAS), the genetic components contributing to different clinical sub-phenotypes of systemic sclerosis (SSc). We considered limited (lcSSc) and diffuse (dcSSc) cutaneous involvement, and the relationships with presence of the SSc-specific auto-antibodies, anti-centromere (ACA), and anti-topoisomerase I (ATA). Four GWAS cohorts, comprising 2,296 SSc patients and 5,171 healthy controls, were meta-analyzed looking for associations in the selected subgroups. Eighteen polymorphisms were further tested in nine independent cohorts comprising an additional 3,175 SSc patients and 4,971 controls. Conditional analysis for associated SNPs in the HLA region was performed to explore their independent association in antibody subgroups. Overall analysis showed that non-HLA polymorphism rs11642873 in IRF8 gene to be associated at GWAS level with lcSSc (P = 2.32×10(-12), OR = 0.75). Also, rs12540874 in GRB10 gene (P = 1.27 × 10(-6), OR = 1.15) and rs11047102 in SOX5 gene (P = 1.39×10(-7), OR = 1.36) showed a suggestive association with lcSSc and ACA subgroups respectively. In the HLA region, we observed highly associated allelic combinations in the HLA-DQB1 locus with ACA (P = 1.79×10(-61), OR = 2.48), in the HLA-DPA1/B1 loci with ATA (P = 4.57×10(-76), OR = 8.84), and in NOTCH4 with ACA P = 8.84×10(-21), OR = 0.55) and ATA (P = 1.14×10(-8), OR = 0.54). We have identified three new non-HLA genes (IRF8, GRB10, and SOX5) associated with SSc clinical and auto-antibody subgroups. Within the HLA region, HLA-DQB1, HLA-DPA1/B1, and NOTCH4 associations with SSc are likely confined to specific auto-antibodies. These data emphasize the differential genetic components of subphenotypes of SSc.

Clinical significance of coexisting antitopoisomerase I and anticentromere antibodies in patients with systemic sclerosis: a EUSTAR group-based study.

OBJECTIVES: To determine the clinical characteristics of simultaneous occurrence of antitopoisomerase (ATA) and anticentromere (ACA) autoantibodies in systemic sclerosis (SSc). METHODS: Data of patients (n=4,687) fulfilling the ACR criteria for SSc and followed in the EULAR Scleroderma Trials and Research (EUSTAR) cohort were analysed. Sera from patients with simultaneous ATA and ACA were reanalyzed centrally by indirect immunofluorescence, enzyme immunoassay, and immunoblot to confirm antibody status. RESULTS: A total of 29 patients (0.6%) had been documented double-positive for both ATA and ACA in the EUSTAR database. Sera of 14 cases were available for central analysis, of which 8 were confirmed to unequivocally contain both antibodies. The double-positive patients were on average 52.4 years of age, 87.5% were female, and 62.5% had diffuse cutaneous (dc) SSc. Compared with matched ACA single-positive disease, cutaneous and visceral complications were more prevalent in double-positive cases, but this prevalence did not differ significantly in comparison to ATA single-positives. CONCLUSIONS: Coexistence of ATA and ACA can be found at low prevalence in SSc. The clinical features of double-positive patients are not clearly dissimilar to those of patients harbouring only ATA. The data do not support a direct involvement of these antibodies in the pathogenesis of established SSc, but may lack statistical power.

Confirmation of association of the macrophage migration inhibitory factor gene with systemic sclerosis in a large European population.

OBJECTIVES: The aim of this study was to confirm the implication of macrophage migration inhibitory factor (MIF) gene in SSc susceptibility or clinical phenotypes in a large European population. METHODS: A total of 3800 SSc patients and 4282 healthy controls of white Caucasian ancestry from eight different European countries were included in the study. The MIF -173 single nucleotide polymorphism (SNP) was selected as genetic marker and genotyped using Taqman 5' allelic discrimination assay. RESULTS: The MIF -173 SNP showed association with SSc [P = 0.04, odds ratio (OR) = 1.10, 95% CI 1.00, 1.19]. Analysis of the MIF -173 polymorphism according to SSc clinical phenotype revealed that the frequency of the -173*C allele was significantly higher in the dcSSc group compared with controls (P = 5.30E-03, OR = 1.21, 95% CI 1.07, 1.38). Conversely, the frequency of the MIF -173*C allele was significantly underrepresented in the lcSSc group compared with dcSSc patients, supporting previous findings [(P = 0.04, OR = 0.86, 95% CI 0.75, 0.99); meta-analysis including previous results (P = 0.005, OR = 0.83, 95% CI 0.73, 0.94)]. CONCLUSION: Our results confirm the role of MIF -173 promoter polymorphism in SSc, and provide evidence of a strong association with the dcSSc subgroup of patients. Hence, the MIF -173 variant is confirmed as a promising clinical phenotype genetic marker.

Incidence, prevalence and long-term progression of Goh algorithm rated interstitial lung disease in systemic sclerosis in two independent cohorts in flanders: A retrospective cohort study.

OBJECTIVES: The epidemiology of interstitial lung disease (ILD) in systemic sclerosis (SSc) in Belgium is unknown. In literature, its prevalence varies between 19% and 52% in limited/diffuse cutaneous SSc (LcSSc/DcSSc). However, its prevalence in "early" SSc (pre-clinically overt SSc without [yet] skin involvement), nor its incidence rate in SSc (LcSSc/DcSSc/"early" SSc) has ever been described. Against this background, we aimed to determine the prevalence/incidence (rate) and progression of ILD in SSc. METHODS: 12-year follow-up data of consecutive SSc patients, included in two Flemish cohorts (University Hospitals Ghent and Leuven), were retrospectively analysed. ILD was classified according to the simplified Goh algorithm. Progression of ILD was defined as a relative decline of FVC ≥10%, a combined relative decline of FVC 5-10% and DLCO ≥15%, or as an increase in HRCT extent. RESULTS: 722 patients (60% LcSSc/ 20% DcSSc/ 20% "early" SSc, median (IQR) follow-up 39 [12-80] months) had baseline HRCT. 243 were rated to have ILD at baseline and 39 during follow-up (prevalence of 34%/ incidence rate of 20.3/1000PY, 95%CI:14.5-27.8). Amongst those with baseline ILD, 60% had lung functional progression at five years of follow-up. In the "early" SSc subgroup, eight patients were rated to have ILD at baseline and three during follow-up (prevalence of 6%/ incidence rate of 5.8/1000 PY, 95%CI:1.2-17.0). CONCLUSION: Both LcSSc and DcSSc patients should be monitored for ILD evolution. The low prevalence and incidence of ILD in the "early" SSc subgroup may instruct future decisions on the construction of uniform patient follow-up pathways in "early" SSc.

High prevalence of occupational exposure to solvents or silica in male systemic sclerosis patients: a Belgian cohort analysis.

Increasing evidence supports a relation of some occupational exposures to systemic sclerosis pathogenesis. We aimed to evaluate occupational exposure and clinical characteristics in male patients with systemic sclerosis followed in two Belgian academic hospitals. One hundred and three male patients, included in the Belgian Systemic Sclerosis Cohort, were identified. An expert in occupational medicine reviewed the occupational history and allocated the patients to one of the following groups: probable exposure to crystalline silica, probable exposure to solvents, probable exposure to other toxins, or no suspected occupational exposure. Clinical characteristics were extracted from the Belgian Systemic Sclerosis Cohort database. Sufficient data were available for 96/103 patients. Most of these male patients (70/96, 72.9%) had a history of occupational exposure, 55 patients were likely exposed to crystalline silica, 11 patients to solvents, 2 patients to both silica and solvents, and 2 patients to asbestos. Only 26 patients had no suspected occupational exposure (27.1%). We noticed a significant difference in smoking status between exposed and non-exposed patients, with the highest percentage of ever smokers in the group with solvent exposure (p = 0.011). We found no significant differences in disease phenotype between exposed and non-exposed patients. However, we noted a trend to a higher prevalence of anti-Scl70 antibodies, cardiac dysfunction, and higher disease activity score in patients with occupational exposure. We observed a strikingly high prevalence of occupational exposure to both silica and solvents in male systemic sclerosis patients. Occupational exposure to silica or solvents is highly prevalent in male systemic sclerosis patients.

Two years follow-up of an open-label pilot study of treatment with rituximab in patients with early diffuse cutaneous systemic sclerosis.

OBJECTIVES: Following results in open-label studies of rituximab in patients with systemic sclerosis, a Belgian three-centre initiative was launched to explore safety and efficacy of rituximab in early, diffuse cutaneous systemic sclerosis (dcSSc). METHODS: Open-label study of 17 patients with early dcSSc, treated with two courses of rituximab, at month 0 and 6. Clinical examination, lung function testing, echocardiography, disease activity score (DAS) and functional status were performed at baseline and over 24 months of follow-up. RESULTS: Modified Rodnan skin score (MRSS) changed significantly over time, with a mean of 25.5 (standard deviation [SD] 6.0) at baseline to 12.6 (SD 5.1) at month 24 (Mixed Model Analysis [MMA] p < 0.0001), which is a decrease of 51% at month 24 vs. baseline. DAS showed significant decrease over the total study period, with a score of 4.1 (SD 1.7) at baseline to 1.5 (SD 1.8) at month 24 (MMA p < 0.0001). Additionally, this was significant at all time points vs. baseline, both for MRSS and DAS. Internal organ status remained clinically stable throughout the study period. No statistically significant differences compared to baseline were found at the follow-up time points. Seven serious adverse events took place, all except for one, considered unrelated to study medication. CONCLUSIONS: This is the first multicentre Belgian collaboration investigating potential efficacy of rituximab in early dcSSc. Rituximab appears to be safe and tolerable and it may have beneficial effects on skin involvement, on overall disease activity and on stabilization of internal organ status in early dcSSc.

Systemic sclerosis: state of the art on clinical practice guidelines.

Systemic sclerosis (SSc) is an orphan disease characterised by autoimmunity, fibrosis of the skin and internal organs, and vasculopathy. SSc may be associated with high morbidity and mortality. In this narrative review we summarise the results of a systematic literature research, which was performed as part of the European Reference Network on Rare and Complex Connective Tissue and Musculoskeletal Diseases project, aimed at evaluating existing clinical practice guidelines or recommendations. Only in the domains 'Vascular & Ulcers' (ie, non-pharmacological approach to digital ulcer), 'PAH' (ie, screening and treatment), 'Treatment' and 'Juveniles' (ie, evaluation of juveniles with Raynaud's phenomenon) evidence-based and consensus-based guidelines could be included. Hence there is a preponderance of unmet needs in SSc referring to the diagnosis and (non-)pharmacological treatment of several SSc-specific complications. Patients with SSc experience significant uncertainty concerning SSc-related taxonomy, management (both pharmacological and non-pharmacological) and education. Day-to-day impact of the disease (loss of self-esteem, fatigue, sexual dysfunction, and occupational, nutritional and relational problems) is underestimated and needs evaluation.

Efficacy of golimumab in Belgian patients with active rheumatoid arthritis despite treatment with non-biologic disease-modifying anti-rheumatic drugs: sub-analysis of the GO-MORE study.

OBJECTIVES: The GO-MORE trial (NCT00975130) was a phase 3 study in 40 countries evaluating the efficacy and safety of golimumab as add-on therapy in biologic-naïve adults with active rheumatoid arthritis despite stable treatment with disease-modifying anti-rheumatic drugs. To inform local practice in Belgium and examine the role of baseline disease activity in treatment response, we compared the efficacy of golimumab in the Belgian subpopulation and the rest of the world. METHODS: Baseline disease activity and six-month efficacy rates in the GO-MORE trial were compared for the Belgian subpopulation and the rest of the world by t-tests and chi-squared tests. RESULTS: Except for functional impairment, all measures of baseline disease activity were significantly lower (p < 0.0001) in the Belgian population (n = 123) than in the rest of the world (n = 3157). At month six, the rate of good/moderate EULAR response was similar in Belgium and the rest of the world (78.9% vs. 82.2%; p = 0.34), but remission rates were higher in Belgium according to the DAS28-ESR (43.1% vs. 23.2%; p < 0.0001) and Simplified Disease Activity Index (22.0% vs. 13.8%; p = 0.01). Rates of low DAS28-ESR disease activity were also higher in Belgium (54.5% vs. 36.8%; p < 0.0001). Within the Belgian subpopulation, efficacy measures were not significantly different between patients with moderate (n = 73) and high baseline activity (n = 49). Rates of functional impairment at month six did not differ between the two populations. CONCLUSION: In the Belgian population of the GO-MORE trial, baseline disease activity was lower and six-month remission rates were higher than in the rest of the world.

The association of illness perceptions with physical and mental health in systemic sclerosis patients: an exploratory study.

OBJECTIVE: The aim of the present study was to evaluate the association between illness perceptions and the ability to cope with physical and mental health problems in a large cohort of systemic sclerosis (SSc) patients. METHODS: This was a cross-sectional study in 217 systemic sclerosis patients from the Belgian Systemic Sclerosis Cohort. Illness perception and coping were measured by the Revised Illness Perception Questionnaire and a coping questionnaire--the Coping Orientation of Problem Experience inventory (COPE). Physical and mental health-related quality of life was measured by the 36-item short-form health survey (SF-36), as were disease activity and several severity parameters. The relationship between illness perceptions and the ability to cope with physical/mental health problems was examined using multiple linear regression analysis. RESULTS: According to LeRoy's classification, 49 patients had limited SSc (lSSc), 129 had limited cutaneous SSc (lcSSc) and 39 had diffuse cutaneous SSc (dcSSc). Median disease duration was five years and the modified Rodnan skin score was 4. Good physical health was significantly associated with the lcSSc subtype and low disease activity (p < 0.01 and p < 0.05, respectively). The perception of 'serious consequences' and strong 'illness identity' correlated with poor physical health (p < 0.001). Good mental health was associated with low illness identity scores and low 'emotional response' scores (p < 0.001). Coping variables were less significantly correlated with physical and mental health compared with the illness perception items. CONCLUSION: Illness representations contribute more than classical disease characteristics to physical and mental health.

The Belgian Systemic Sclerosis Cohort: correlations between disease severity scores, cutaneous subsets, and autoantibody profile.

OBJECTIVE: To report baseline and followup data on the first 438 patients with systemic sclerosis (SSc) included in the Belgian Systemic Sclerosis Cohort. METHODS: According to LeRoy and Medsger's classification, 73 patients with limited SSc (lSSc), 279 with limited cutaneous SSc (lcSSc), and 86 with diffuse cutaneous SSc (dcSSc) were included. History was collected and clinical examination, blood tests, and paraclinical investigations were repeated. The Disease Activity Score (DAS) and Disease Severity Score (DSS) of several organ systems were computed. An organ system was considered to demonstrate SSc if the corresponding DSS was ≥ 1. RESULTS: At baseline, patients with dcSSc had more general, joint/tendon, muscle, gastrointestinal, and kidney involvement. Mean DLCO was below normal in patients with lSSc, indicating unsuspected lung involvement. Patients with anti-Scl-70 had more vascular, skin, joint/tendon, and lung involvement. Patients with anti-RNA polymerase III had more skin and joint/tendon involvement compared to patients with anticentromere. Time to death was statistically shorter for patients with dcSSc. New-onset lung disease was the most common complication over time. No changes in DAS were observed. By contrast, the general and the skin DSS worsened in patients with lcSSc and lSSc, respectively. Fifteen percent of patients with lSSc shifted to lcSSc at Month 30, but neither serology nor capillaroscopy findings at baseline were helpful in identifying those at risk. CONCLUSION: Our data indicate that the DSS can be used to define organ involvement in SSc. Differences can be seen between subsets classified not only according to cutaneous subtypes but also to autoantibody profile.

Hand radiological damage in systemic sclerosis: comparison with a control group and clinical and functional correlations.

OBJECTIVE: To define the burden of hand radiological damage in systemic sclerosis (SSc) patients, compared with a control group. METHODS: Both hands of 167 SSc patients and 168 hands (82 right and 86 left) of age- and gender-matched controls were imaged by conventional radiograph. Two musculoskeletal radiologists semiquantitatively scored the following lesions: tuft acro-osteolysis, tuft calcinosis, joint space narrowings, marginal erosions, surface erosions, collapse arthropathies, periarticular calcifications, and juxta-articular osteoporosis, at the following areas: tufts, distal interphalangeal, proximal interphalangeal, metacarpophalangeal, carpal, and first carpometacarpal joints. Clinical and functional characteristics of the 167 SSc patients were obtained from the Belgian Systemic Sclerosis Cohort database. RESULTS: Tuft acro-osteolysis and calcinosis were the most common findings observed in SSc patients and were almost absent in controls. SSc patients displaying tuft acro-osteolysis/calcinosis suffered from more severe disease. Arthropathies were infrequently detected and mainly consisted of a mixture of osteoarthritis-related changes (joint space narrowing and surface erosions)-also observed in controls-and of 2 types of rare SSc-associated arthropathies: a rheumatoid arthritis-like pattern, characterized by marginal erosions (n = 7 patients), and a collapse arthropathy (n = 6 patients), characterized by pressure erosions and joint subluxation. CONCLUSIONS: Although a rheumatoid arthritis-like or a collapse arthropathy can be observed in SSc patients, arthropathies are less common than previously reported.

Validation of a manual ability questionnaire in patients with systemic sclerosis.

OBJECTIVE: To adapt and validate a manual ability questionnaire, the ABILHAND, developed through the Rasch methodology in patients with systemic sclerosis (SSc). METHODS: The original version of the ABILHAND, which includes 81 manual daily activities, was presented to 156 patients with SSc. They were asked to provide their perceived difficulty in performing each manual activity on a 3-level scale: impossible, difficult, or easy. Items were selected from well-established psychometric criteria. The patients were reassessed 1 month later to test the reproducibility. Concomitantly, they were clinically evaluated for their disease activity/severity, and their functional ability was tested with the Health Assessment Questionnaire (HAQ). RESULTS: The 26 selected items defined a unidimensional and linear measure of manual ability and showed a continuous progression in their difficulty. The item difficulty hierarchy was invariant across 12 patient-related factors and the manual ability score was reproducible over time. Finally, the manual ability was significantly poorer in SSc patients with more severe disease, and was negatively correlated with the HAQ score (rho = -0.733). CONCLUSION: The SSc-adapted ABILHAND questionnaire is a reliable, valid, reproducible, linear, and unidimensional measure to assess and followup on the manual ability of patients with SSc; therefore, it could become a useful additional tool in clinical trials to assess treatment efficacy.

Lack of evidence of stimulatory autoantibodies to platelet-derived growth factor receptor in patients with systemic sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is a severe connective tissue disease of unknown etiology, characterized by fibrosis of the skin and multiple internal organs. Recent findings suggested that the disease is driven by stimulatory autoantibodies to platelet-derived growth factor receptor (PDGFR), which stimulate the production of reactive oxygen species (ROS) and collagen by fibroblasts. These results opened novel avenues of research into the diagnosis and treatment of SSc. The present study was undertaken to confirm the presence of anti-PDGFR antibodies in patients with SSc. METHODS: Immunoglobulins from 37 patients with SSc were purified by protein A/G chromatography. PDGFR activation was tested using 4 different sensitive bioassays, i.e., cell proliferation, ROS production, signal transduction, and receptor phosphorylation; the latter was also tested in a separate population of 7 patients with SSc from a different research center. RESULTS: Purified IgG samples from patients with SSc were positive when tested for antinuclear autoantibodies, but did not specifically activate PDGFRalpha or PDGFRbeta in any of the tests. Cell stimulation with PDGF itself consistently produced a strong signal. CONCLUSION: The present results raise questions regarding the existence of agonistic autoantibodies to PDGFR in SSc.