Systemic sclerosis: The need for structured care

Autoimmune connective tissue diseases (CTDs) have a propensity to affect multiple organ systems as well as physical function, quality of life, and survival. Their clinical heterogeneity, multisystem involvement, and low worldwide prevalence present challenges for researchers to establish a study design to help better understand the course and outcomes of CTDs. Systemic sclerosis (SSc) is a notable example of a CTD, wherein longitudinal cohort studies (LCS) have enabled us to elucidate disease manifestations, disease course, and risk and prognostic factors for clinically important outcomes, by embedding research in clinical practice. Nevertheless, further efforts are needed to better understand SSc especially with regard to recognizing organ involvement early, developing new therapies, optimizing the use of existing therapies, and defining treatment targets. The heterogeneous multi-organ nature of SSc would lend itself well to a structured model of care, wherein step-up treatment algorithms are used with the goal of attaining a prespecified treatment target. In this chapter, we discuss the rationale for a structured treatment approach in SSc and propose possible treatment algorithms for three of the more common disease manifestations, namely skin involvement, digital ulcers and gastrointestinal tract involvement. We discuss possible strategies for evaluating and implementing these algorithms in the setting of LCS. We conclude by presenting a research agenda for the development of structured models of care in SSc.

Prediction of improvement in skin fibrosis in diffuse cutaneous systemic sclerosis: a EUSTAR analysis

Objectives

Improvement of skin fibrosis is part of the natural course of diffuse cutaneous systemic sclerosis (dcSSc). Recognising those patients most likely to improve could help tailoring clinical management and cohort enrichment for clinical trials. In this study, we aimed to identify predictors for improvement of skin fibrosis in patients with dcSSc.

Methods

We performed a longitudinal analysis of the European Scleroderma Trials And Research (EUSTAR) registry including patients with dcSSc, fulfilling American College of Rheumatology criteria, baseline modified Rodnan skin score (mRSS) ≥7 and follow-up mRSS at 12±2 months. The primary outcome was skin improvement (decrease in mRSS of >5 points and ≥25%) at 1 year follow-up. A respective increase in mRSS was considered progression. Candidate predictors for skin improvement were selected by expert opinion and logistic regression with bootstrap validation was applied.

Results

From the 919 patients included, 218 (24%) improved and 95 (10%) progressed. Eleven candidate predictors for skin improvement were analysed. The final model identified high baseline mRSS and absence of tendon friction rubs as independent predictors of skin improvement. The baseline mRSS was the strongest predictor of skin improvement, independent of disease duration. An upper threshold between 18 and 25 performed best in enriching for progressors over regressors.

Conclusions

Patients with advanced skin fibrosis at baseline and absence of tendon friction rubs are more likely to regress in the next year than patients with milder skin fibrosis. These evidence-based data can be implemented in clinical trial design to minimise the inclusion of patients who would regress under standard of care.

Effect of Gd-DOTA on fat quantification in skeletal muscle using two-point Dixon technique - preliminary data

PURPOSE

To assess differences in fat signal fraction (FSF) in skeletal muscle as determined by two-point Dixon technique at 3T before and after application of intravenous gadoterate meglumide (Gd-DOTA).

MATERIALS AND METHODS

Eight patients (mean age, 50.8 years; range, 41-72 years) underwent clinical whole-body MRI at 3T for myopathic symptoms. Two-point Dixon technique based T1-weighted turbo spin-echo images were acquired before and after the administration of intravenous Gd-DOTA. On both image sets, the FSF was calculated in the gluteus medius, gluteus maximus, and quadriceps muscles bilaterally. Pre- and post-contrast FSF values were compared by linear regression, Bland-Altman plot as well as paired Student t-tests with Bonferroni correction.

RESULTS

The mean pre- and post-contrast FSF of included muscles were 28.7%±14.9% and 27.8%±15.1%, respectively. Linear regression indicated almost equivalent FSF estimation between pre- and post-contrast measurements (sum of squared residuals R(2), 0.92±0.04; slope, 0.97; X-intercept, -0.05; Y-intercept, +0.05). The Bland-Altman plot revealed a minimal systematical bias of the post-contrast FSF measurements of -0.87%. Paired Student t-tests did not reveal significant differences (overall p-value, 0.168).

CONCLUSION

Gd-DOTA does not significantly influence FSF quantification in skeletal muscle based on the two-point Dixon technique at 3T.

Dense genotyping of immune-related loci in idiopathic inflammatory myopathies confirms HLA alleles as the strongest genetic risk factor and suggests different genetic background for major clinical subgroups

OBJECTIVES

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases characterised by muscle weakness and extramuscular manifestations such as skin rashes and interstitial lung disease. We genotyped 2566 IIM cases of Caucasian descent using the Immunochip; a custom array covering 186 established autoimmune susceptibility loci. The cohort was predominantly comprised of patients with dermatomyositis (DM, n=879), juvenile DM (JDM, n=481), polymyositis (PM, n=931) and inclusion body myositis (n=252) collected from 14 countries through the Myositis Genetics Consortium.

RESULTS

The human leucocyte antigen (HLA) and PTPN22 regions reached genome-wide significance (p<5×10(-8)). Nine regions were associated at a significance level of p<2.25×10(-5), including UBE2L3, CD28 and TRAF6, with evidence of independent effects within STAT4. Analysis of clinical subgroups revealed distinct differences between PM, and DM and JDM. PTPN22 was associated at genome-wide significance with PM, but not DM and JDM, suggesting this effect is driven by PM. Additional suggestive associations including IL18R1 and RGS1 in PM and GSDMB in DM were identified. HLA imputation confirmed that alleles HLA-DRB1*03:01 and HLA-B*08:01 of the 8.1 ancestral haplotype (8.1AH) are most strongly associated with IIM, and provides evidence that amino acids within the HLA, such as HLA-DQB1 position 57 in DM, may explain part of the risk in this locus. Associations with alleles outside the 8.1AH reveal differences between PM, DM and JDM.

CONCLUSIONS

This work represents the largest IIM genetic study to date, reveals new insights into the genetic architecture of these rare diseases and suggests different predominating pathophysiology in different clinical subgroups.

Downregulation of miR-193b in systemic sclerosis regulates the proliferative vasculopathy by urokinase-type plasminogen activator expression

OBJECTIVES

To investigate the role of microRNA-193b-3p (miR-193b) in the vascular pathophysiology of systemic sclerosis (SSc).

METHODS

Expression of miR-193b in skin biopsies and fibroblasts from patients with SSc and normal healthy (NH) controls were determined by real-time PCR. Transfection with miR-193b precursor and inhibitor were used to confirm targets of miR-193b. Proliferative effects of urokinase-type plasminogen activator (uPA) were determined by water-soluble tetrazolium salt-1 assay and by analysis of proliferating cell nuclear antigen expression. Fluorescence activated cell sorting analysis was performed to investigate the effect of uPA on apoptosis. For inhibition of the uPA-cellular receptor for uPA (uPAR) pathway, uPAR neutralising antibodies and low molecular weight uPA were used.

RESULTS

We found that miR-193b was downregulated in SSc fibroblasts and skin sections as compared with NH controls. The expression of miR-193b was not affected by major profibrotic cytokines and hypoxia. Induction of miR-193b in SSc fibroblasts suppressed, and accordingly, knockdown of miR-193b increased the levels of messenger RNA and protein for uPA. uPA was found to be upregulated in SSc as compared with NH controls in a transforming growth factor-β dependent manner, and uPA was strongly expressed in vascular smooth muscle cells in SSc skin section. Interestingly, uPA induced cell proliferation and inhibited apoptosis of human pulmonary artery smooth muscle cells, and these effects were independent of uPAR signalling.

CONCLUSIONS

In SSc, the downregulation of miR-193b induces the expression of uPA, which increases the number of vascular smooth muscle cells in an uPAR-independent manner and thereby contributes to the proliferative vasculopathy with intimal hyperplasia characteristic for SSc.

Prediction of worsening of skin fibrosis in patients with diffuse cutaneous systemic sclerosis using the EUSTAR database

Objectives

To identify predictive parameters for the progression of skin fibrosis within 1 year in patients with diffuse cutaneous SSc (dcSSc).

Methods

An observational study using the EUSTAR database was performed. Inclusion criteria were dcSSc, American College of Rheumatology (ACR) criteria fulfilled, modified Rodnan skin score (MRSS) ≥7 at baseline visit, valid data for MRSS at 2nd visit, and available follow-up of 12±2 months. Worsening of skin fibrosis was defined as increase in MRSS >5 points and ≥25% from baseline to 2nd visit. In the univariate analysis, patients with progressive fibrosis were compared with non-progressors, and predictive markers with p<0.2 were included in the logistic regression analysis. The prediction models were then validated in a second cohort.

Results

A total of 637 dcSSc patients were eligible. Univariate analyses identified joint synovitis, short disease duration (≤15 months), short disease duration in females/patients without creatine kinase (CK) elevation, low baseline MRSS (≤22/51), and absence of oesophageal symptoms as potential predictors for progressive skin fibrosis. In the multivariate analysis, by employing combinations of the predictors, 17 models with varying prediction success were generated, allowing cohort enrichment from 9.7% progressive patients in the whole cohort to 44.4% in the optimised enrichment cohort. Using a second validation cohort of 188 dcSSc patients, short disease duration, low baseline MRSS and joint synovitis were confirmed as independent predictors of progressive skin fibrosis within 1 year resulting in a 4.5-fold increased prediction success rate.

Conclusions

Our study provides novel, evidence-based criteria for the enrichment of dcSSc cohorts with patients who experience worsening of skin fibrosis which allows improved clinical trial design.

Effects and safety of rituximab in systemic sclerosis: an analysis from the European Scleroderma Trial and Research (EUSTAR) group

OBJECTIVES

To assess the effects of Rituximab (RTX) on skin and lung fibrosis in patients with systemic sclerosis (SSc) belonging to the European Scleroderma Trial and Research (EUSTAR) cohort and using a nested case-control design.

METHODS

Inclusion criteria were fulfilment of American College of Rheumatology classification criteria for SSc, treatment with RTX and availability of follow-up data. RTX-treated patients were matched with control patients from the EUSTAR database not treated with RTX. Matching parameters for skin/lung fibrosis were the modified Rodnan Skin Score (mRSS), forced vital capacity (FVC), follow-up duration, scleroderma subtype, disease duration and immunosuppressive co-treatment. The primary analysis was mRSS change from baseline to follow-up in the RTX group compared with the control group. Secondary analyses included change of FVC and safety measures.

RESULTS

63 patients treated with RTX were included in the analysis. The case-control analysis in patients with severe diffuse SSc showed that mRSS changes were larger in the RTX group versus matched controls (N=25; -24.0±5.2% vs -7.7±4.3%; p=0.03). Moreover, in RTX-treated patients, the mean mRSS was significantly reduced at follow-up compared with baseline (26.6±1.4 vs 20.3±1.8; p=0.0001). In addition, in patients with interstitial lung disease, RTX prevented significantly the further decline of FVC compared with matched controls (N=9; 0.4±4.4% vs -7.7±3.6%; p=0.02). Safety measures showed a good profile consistent with previous studies in autoimmune rheumatic diseases.

CONCLUSIONS

The comparison of RTX treated versus untreated matched-control SSc patients from the EUSTAR cohort demonstrated improvement of skin fibrosis and prevention of worsening lung fibrosis, supporting the therapeutic concept of B cell inhibition in SSc.

Levels of target activation predict antifibrotic responses to tyrosine kinase inhibitors

Objectives

To assess whether the discrepancy between the strong antifibrotic effects of tyrosine kinase inhibitors (TKIs) in animal models and the inconsistent results in clinical studies might be related to the activation levels of drug targets.

Methods

Skin sections of bleomycin, TSK1, Fra-2 transgenic mice, SSc patients and controls were analysed by histology and immunohistochemistry. Subgroups of mice were treated with the TKIs nilotinib or imatinib. Differences in the activation levels of the TKI targets p-PDGFRβ (platelet derived growth factor β) and p-c-abl were assessed.

Results

In bleomycin and TSK1 mice, expression of activated p-PDGFRβ (platelet derived growth factor receptor β) and p-c-abl was ubiquitous with strong upregulation compared with controls. Treatment with TKIs resulted in successful target inhibition and consequently reduced dermal fibrosis. In the Fra-2 model, the activation levels of p-PDGFRβ and p-c-abl were much lower than in the bleomycin and the TSK1 models. Accordingly, nilotinib did not prevent dermal fibrosis and target inhibition was unsuccessful. Notably, in skin biopsies of SSc patients, the mean activation levels of TKI targets were only moderate and in the majority of patients resembled those of the non-responsive Fra-2 model.

Conclusions

Animal models for proof-of-concept studies should be selected based on a similar activation level and expression pattern of drug targets as in human SSc.

Vascular endothelial growth factor aggravates fibrosis and vasculopathy in experimental models of systemic sclerosis

OBJECTIVES

High levels of vascular endothelial growth factor (VEGF), a key angiogenic factor, are present in patients with systemic sclerosis (SSc), but its role in the pathogenesis of fibrosis and its contribution to the disturbed angiogenesis of SSc remains hypothetical.

METHODS

Mono (+/-) and double (+/+) VEGF transgenic (tg) mice and their wildtype (wt) controls were analysed. The bleomycin model was applied to VEGF tg mice to evaluate effects of VEGF under proinflammatory conditions. Additionally, tight skin (TSK) 1/VEGF+/+ mice were generated to mimic later non-inflammatory stages of SSc.

RESULTS

VEGF+/+, but not VEGF+/- tg mice, spontaneously developed significant skin fibrosis, indicating profibrotic effect of VEGF in a gene-dosing manner. In the proinflammatory bleomycin model, the profibrotic effect became more pronounced with induction of skin fibrosis in VEGF+/- tg mice and even more enhanced fibrosis in VEGF+/+ tg mice. Analysis in TSK1/VEGF+/+ mice showed similar profibrotic effects of VEGF also under non-inflammatory in vivo conditions. In vitro analysis revealed that VEGF is able to directly induce collagen synthesis in dermal fibroblasts. Additionally, there was an inverse gene-dosing effect on the efficacy of angiogenesis in that a higher number of microvessels was observed in VEGF+/- tg mice than in VEGF+/+ tg mice.

CONCLUSIONS

These data provide the first evidence for VEGF as a novel molecular link between fibrosis and vasculopathy in the pathogenesis of SSc. They suggest that high levels of VEGF potently induce fibrosis in inflammatory and non-inflammatory stages, and also contribute to the relatively insufficient angiogenesis characteristic for SSc.

Emerging targeted therapies in scleroderma lung and skin fibrosis

Systemic sclerosis (SSc) is a multisystemic fibrotic disorder that affects the skin and internal organs. Despite an improved outcome probably reflecting a better management of disease complications, morbidity and mortality remain higher than those of patients with other connective tissue diseases. SSc is still considered incurable; however, during recent years, intensive research activities have deepened the understanding of pathogenic mechanisms and have led to the identification of cellular and molecular anti-fibrotic targets. This review article will discuss potential future targeted therapeutic options based on data from in vitro studies, experimental models of fibrosis and first human trials with focus on scleroderma skin and lung fibrosis.

Outcomes of patients with systemic sclerosis-associated polyarthritis and myopathy treated with tocilizumab or abatacept: a EUSTAR observational study

OBJECTIVE

To evaluate the safety and effectiveness of tocilizumab and abatacept in systemic sclerosis (SSc)-polyarthritis or SSc-myopathy.

METHODS

20 patients with SSc with refractory polyarthritis and seven with refractory myopathy from the EUSTAR (EULAR Scleroderma Trials and Research) network were included: 15 patients received tocilizumab and 12 patients abatacept. All patients with SSc-myopathy received abatacept. Clinical and biological assessments were made at the start of treatment and at the last infusion.

RESULTS

After 5 months, tocilizumab induced a significant improvement in the 28-joint count Disease Activity Score and its components, with 10/15 patients achieving a EULAR good response. Treatment was stopped in two patients because of inefficacy. After 11 months' treatment of patients with abatacept, joint parameters improved significantly, with 6/11 patients fulfilling EULAR good-response criteria. Abatacept did not improve muscle outcome measures in SSc-myopathy. No significant change was seen for skin or lung fibrosis in the different groups. Both treatments were well tolerated.

CONCLUSIONS

In this observational study, tocilizumab and abatacept appeared to be safe and effective on joints, in patients with refractory SSc. No trend for any change of fibrotic lesions was seen but this may relate to the exposure time and inclusion criteria. Larger studies with longer follow-up are warranted to further determine the safety and effectiveness of these drugs in SSc.

The Fra-2 transgenic mouse model of systemic sclerosis

In systemic sclerosis, microvascular injury often precedes the development of fibrosis. Whereas the development of digital ulcers and skin fibrosis causes high morbidity, the affection of internal organs, in particular complications such as interstitial lung disease and pulmonary (arterial) hypertension, account for the high disease-associated mortality of these patients. Vascular animal models of systemic sclerosis are of utmost importance to study pathophysiological aspects, to identify molecular key players, and to perform interventional proof of concept-studies. So far, animal models of systemic sclerosis have mainly reflected the pro-fibrotic features of the human disease. The Fra-2 (Fos-related antigen-2) transgenic mouse model simultaneously displays both pro-fibrotic and vascular characteristics of human systemic sclerosis.

A chick embryo with a yet unclassified type of cephalothoracopagus malformation and a hypothesis for explaining its genesis

Cephalothoracopagus embryos are conjoined twins, who share parts of their heads, necks and bodies. Our study aims at presenting a detailed morphological analysis of a cephalothoracopagus chick embryo of developmental stage 31. Because none of the existing theories can explain the genesis of the phenotype of this embryo, we also suggest a hypothesis, which explains it. Beside the cephalothoracopagus embryo, we investigated five control embryos. With the aid of the high-resolution episcopic microscopy (HREM) technique, we created digital volume data and three-dimensional (3D) computer models of the organs and arteries of the embryos. We used the 3D models for topological analysis and for measuring the diameters of the great intrathoracic arteries. The malformed embryo showed two body backs, each containing a notochord, spinal cord and dorsal aorta. The body backs continued into separated lower bodies. The embryo had a single, four-chambered heart, single respiratory tract and single upper alimentary tract. The topology of the pharyngeal arch arteries was normal, and the diameters of these arteries were similar to that of the control embryos. We classified the embryo we investigated as a yet unknown malformation and suggest a hypothesis explaining its genesis.