Anti-RNA polymerase III antibodies: a marker of systemic sclerosis with rapid onset and skin thickening progression

Part I: Epidemiology, pathophysiology, and clinical considerations of primary and secondary Raynaud's phenomenon

Raynaud's phenomenon (RP) is a relatively common disease with both primary and secondary forms. It is well understood as a vasospastic condition affecting the acral and digital arteries, resulting in characteristic, well-demarcated color changes typically in the hands and feet in response to cold or stress. Secondary RP (SRP) has been described in association with a variety of rheumatologic and nonrheumatologic diseases, environmental exposures, and/or medications. While both primary RP and SRP may impact the quality of life, SRP may lead to permanent and potentially devastating tissue destruction when undiagnosed and untreated. It is therefore crucial for dermatologists to distinguish between primary and secondary disease forms early in clinical evaluation, investigate potential underlying causes, and risk stratify SRP patients for the development of associated autoimmune connective tissue disease. The epidemiology, pathogenesis, and clinical presentation and diagnosis of both forms of RP are described in detail in this review article.

Mouth opening in systemic sclerosis: Its course over time, determinants and impact on mouth handicap

Objective

Decreased maximal mouth opening is a common and disabling manifestation in systemic sclerosis patients. We aimed to study the course of maximal mouth opening, determinants of smaller maximal mouth opening over time and the burden of smaller maximal mouth opening on mouth handicap.

Methods

Consecutive systemic sclerosis patients participating in the prospective Leiden Combined Care in systemic sclerosis cohort were included. Annual clinical assessment included maximal mouth opening measurement and mouth handicap evaluation (Mouth Handicap in Systemic Sclerosis scale). Presence of microstomia (maximal mouth opening < 30 mm) was studied. Maximal mouth opening over time was assessed on group level and for all patients individually. Baseline characteristics were analysed for their association with smaller maximal mouth opening over time (linear mixed-effects models). Furthermore, cross-sectional association between maximal mouth opening with Mouth Handicap in Systemic Sclerosis scale was assessed (linear regression analysis).

Results

A total of 382 systemic sclerosis patients were studied with median follow-up time of 2.0 years (interquartile range = 0.0-3.0). At baseline, mean maximal mouth opening was 42.2 ± 8.0 mm and 7% suffered from microstomia. Annual decrease of > 5.0 mm in maximal mouth opening during follow-up occurred in 63 patients and was accompanied by increase in disease severity. Disease characteristics at baseline independently predictive for smaller maximal mouth opening over time were: more extended skin subtype; peripheral vasculopathy; pulmonary, renal and gastrointestinal involvement. Smaller maximal mouth opening was significantly associated with more reported mouth handicap.

Conclusion

The course of maximal mouth opening is stable in a majority of systemic sclerosis patients. Still, maximal mouth opening over time was smaller in patients with more severe organ involvement. Although microstomia was infrequent, a smaller maximal mouth opening was significantly associated with more mouth handicap, indicating the importance to address maximal mouth opening in routine care of systemic sclerosis patients.

DNA from macrophages induces fibrosis and vasculopathy through POLR3A/STING/type I interferon axis in systemic sclerosis

OBJECTIVE

To clarify the role of RNA polymerase III A (POLR3A)/type I IFN in the pathogenesis of SSc.

METHODS

Cytosolic DNA and stimulator of IFN genes (STING) pathway in skin or serum of SSc patients were detected by immunofluorescence, immunohistochemistry and western blotting. DNA from human macrophages was transfected to SSc fibroblasts or human umbilical vein endothelial cells (HUVECs) and then markers of POLR3A/STING pathway were detected by real-time qPCR, western blotting and confocal microscopy. After H151 treatment or knocking down POLR3A/STING, type I IFN response, monocytes adhesion and activation of fibroblasts and HUVECs were evaluated. Regulation of IFN regulatory factor 3 (IRF3) on monocyte chemoattractant protein-1 (MCP-1) was determined by chromatin immunoprecipitation. In bleomycin (BLM)-induced SSc mice, the effect of STING knockout or H151 on vasculopathy and fibrosis was assessed.

RESULTS

Cytosolic DNA, colocalization of STING with alpha-smooth muscle actin (α-SMA) or CD31 in the skin, and STING pathway in the serum of SSc patients were increased. Macrophage-derived DNA stimulated the translocation of POLR3A from nucleus to the perinuclear region near STING and activated POLR3A/STING/type I IFN response, monocytes adhesion and MCP-1 expression in fibroblasts/HUVECs and collagen overproduction of fibroblasts. The activated IRF3 bound to the promoter of MCP-1. STING deficiency or H151 administration ameliorated fibrosis and vasculopathy both in vitro and in BLM-induced SSc mice.

CONCLUSIONS

SSc presented increased DNA leakage and STING pathway activation. DNA from macrophages induced type I IFN signature of fibroblasts and ECs through POLR3A/STING pathway. Blocking POLR3A/STING axis provides a new therapeutic target for SSc.

Systemic Sclerosis-Specific Antibodies: Novel and Classical Biomarkers

Disease-specific autoantibodies are considered the most important biomarkers for systemic sclerosis (SSc), due to their ability to stratify patients with different severity and prognosis. Anti-nuclear antibodies (ANA), occurring in subjects with isolated Raynuad's phenomenon, are considered the strongest independent predictors of definite SSc and digital microvascular damage, as observed by nailfold videocapillaroscopy. ANA are present in more than 90% of SSc, but ANA negativity does not exclude SSc diagnosis: a little rate of SSc ANA negative exists and shows a distinct subtype of disease, with less vasculopathy, but more frequent lower gastrointestinal involvement and severe disease course. Anti-centromere, anti-Th/To, and anti-Topoisomerase I antibodies could be considered as classical biomarkers, covering about 60% of SSc and defining patients with well-described cardio-pulmonary complications. In particular, anti-Topoisomerase I represent a risk factor for development of diffuse cutaneous involvement and digital ulcers in the first 3 years of disease, as well as severe interstitial lung disease (ILD). Anti-RNA polymerase III is a biomarker with new clinical implications: very rapid skin thickness progression, gastric antral vascular ectasia, the occurrence of synchronous cancers, and possible association with silicone breast implants rupture. Moreover, novel SSc specific autoantibodies have been globally described in about 10% of "seronegative" SSc patients: anti-elF2B, anti-RuvBL1/2 complex, anti-U11/U12 RNP, and anti-BICD2 depict specific SSc subtypes with severe organ complications. Many autoantibodies could be considered markers of overlap syndromes, including SSc. Anti-Ku are found in 2-7% of SSc, strictly defining the PM/SSc overlap. They are associated with synovitis, joint contractures, myositis, and negatively associated with vascular manifestation of disease. Anti-U3RNP are associated with a well-defined clinical phenotype: Afro-Caribbean male patients, younger at diagnosis, and higher risk of pulmonary hypertension and gastrointestinal involvement. Anti-PM/Scl define SSc patients with high frequency of ILD, calcinosis, dermatomyositis skin changes, and severe myositis. The accurate detection of autoantibodies SSc specific and associated with overlap syndromes is crucial for patients' stratification. ANA should be correctly identified using indirect immunofluorescent assay and a standardized way of patterns' interpretation. The gold-standard technique for autoantibodies' identification in SSc is still considered immunoprecipitation, for its high sensitivity and specificity, but other assays have been widely used in routine practice. The identification of SSc autoantibodies with high diagnostic specificity and high predictive value is mandatory for early diagnosis, a specific follow-up and the possible definition of the best therapy for every SSc subsets. In addition, the validation of novel autoantibodies is mandatory in wider cohorts in order to restrict the gap of so-called seronegative SSc patients.

Management of Endothelial Dysfunction in Systemic Sclerosis: Current and Developing Strategies

Systemic Sclerosis (SSc) is an autoimmune disease marked by dysregulation of the immune system, tissue fibrosis and dysfunction of the vasculature. Vascular damage, remodeling and inadequate endothelial repair are hallmarks of the disease. Since early stages of SSc, damage and apoptosis of endothelial cells (ECs) can lead to perivascular inflammation, oxidative stress and tissue hypoxia, resulting in multiple clinical manifestations. Raynaud's phenomenon, edematous puffy hands, digital ulcers, pulmonary artery hypertension, erectile dysfunction, scleroderma renal crisis and heart involvement severely affect quality of life and survival. Understanding pathogenic aspects and biomarkers that reflect endothelial damage in SSc is essential to guide therapeutic interventions. Treatment approaches described for SSc-associated vasculopathy include pharmacological options to improve blood flow and tissue perfusion and, more recently, cellular therapy to enhance endothelial repair, promote angiogenesis and heal injuries. This mini-review examines the current knowledge on cellular and molecular aspects of SSc vasculopathy, as well as established and developing therapeutic approaches for improving the vascular compartment.

Anti-RNA polymerase III antibodies in systemic sclerosis: Multicentric study from Argentina

OBJECTIVE

To describe the frequency of anti-RNA polymerase III antibody in patients with Systemic Sclerosis (SSc) of a group of healthcare centres from Argentina and to explore differences among patients with positive and negative anti-RNA polymerase III antibody.

PATIENTS AND METHODS

Data from clinical records, anamnesis and physical examination were collected from 135 patients with SSc (ACR/EULAR 2013). A serum sample from each patient was obtained for the detection of anti-RNA polymerase III IgG antibodies by ELISA.

RESULTS

In all, 97.8% were women and the median age at diagnosis was 53 years (range 12-87), 77.7% had limited cutaneous SSc (lcSSC), 19,3% patients had diffuse cutaneous SSc (dcSSC) and 2.9% had scleroderma sine scleroderma. The 67.5% of the patients were from a Mestizos or Amerindian ethnic group. Anti-RNA polymerase III was positive in 5.9% of the patients. In 36 patients, the anticentromere (ACA) and anti-Scl70 antibodies were negative; anti-RNA polymerase III was positive in 16.7% of these 36 patients. Pitting scars and pulmonary artery hypertension were more frequent in anti-RNA polymerase III positive patients who were also older at diagnosis. No association with gastric antral vascular ectasia was found. The only patient with scleroderma renal crisis was anti-RNA polymerase III positive.

CONCLUSIONS

Anti-RNA polymerase III frequency found in this study was one of the lowest reported, which could be related to the predominance of the Amerindian and Mestizo ethnic group. It is possible that the detection of anti RNA polymerase III allows better classification of SSc patients, to know their prognosis and to improve their follow-up, therefore more studies are needed.

Anti-RNA Polymerase III Antibodies in Systemic Sclerosis: Multicentric Study from Argentina

OBJECTIVE

To describe the frequency of anti-RNA polymerase III antibody in patients with Systemic Sclerosis (SSc) of a group of healthcare centres from Argentina and to explore differences among patients with positive and negative anti-RNA polymerase III antibody.

PATIENTS AND METHODS

Data from clinical records, anamnesis and physical examination were collected from 135 patients with SSc (ACR/EULAR 2013). A serum sample from each patient was obtained for the detection of anti-RNA polymerase III IgG antibodies by ELISA.

RESULTS

In all, 97.8% were women and the median age at diagnosis was 53 years (range: 12-87), 77.7% had limited cutaneous SSc (lcSSC), 19,3% patients had diffuse cutaneous SSc (dcSSC) and 2.9% had scleroderma sine scleroderma. The 67.5% of the patients were from a Mestizos or Amerindian ethnic group. Anti-RNA polymerase III was positive in 5.9% of the patients. In 36 patients, the anticentromere (ACA) and anti-Scl70 antibodies were negative; anti-RNA polymerase III was positive in 16.7% of these 36 patients. Pitting scars and pulmonary artery hypertension were more frequent in anti-RNA polymerase III positive patients who were also older at diagnosis. No association with gastric antral vascular ectasia was found. The only patient with scleroderma renal crisis was anti-RNA polymerase III positive.

CONCLUSIONS

Anti-RNA polymerase III frequency found in this study was one of the lowest reported, which could be related to the predominance of the Amerindian and Mestizo ethnic group. It is possible that the detection of anti-RNA polymerase III allows better classification of SSc patients, to know their prognosis and to improve their follow-up, therefore more studies are needed.

Association of Silicone Breast Implants, Breast Cancer and Anti-RNA Polymerase III Autoantibodies in Systemic Sclerosis: Case-Based Review

Some case reports and small case series of patients with silicone breast implant (SBI) have reported the development of systemic sclerosis (SSc) many years later, despite conflicting evidence of this association in the literature. Recently, patients with SSc and anti-RNA polymerase III antibodies positivity have been associated with previous silicone implants and/or breast cancer, showing clinical features that differ from the classic SSc, such as rapid and diffuse cutaneous involvement and scleroderma renal crisis (SRC). The specific autoimmune reaction is not yet fully understood, although knowledge in this regard is increasing. We describe a case that can support these previous observations, strengthening this association which must be taken into account. Clinicians should be aware of this new clinical entity, given the widespread use of silicone implants.

Gastric antral vascular ectasia in systemic sclerosis: Association with anti-RNA polymerase III and negative anti-nuclear antibodies

OBJECTIVE

Gastric antral vascular ectasia (GAVE) is a vascular manifestation of systemic sclerosis (SSc) that can lead to iron deficiency anemia or acute gastrointestinal (GI) bleeding. We aimed to identify clinical features associated with GAVE.

METHODS

We performed a cohort study of SSc patients who were seen at Stanford between 2004 and 2018 and had undergone esophagogastroduodenoscopy (EGD). We compared the clinical features of those with and without GAVE, and multivariable logistic regression was performed to identify clinical correlates with GAVE.

RESULTS

A total of 225 patients with SSc who underwent EGD were included in this study and 19 (8.4%) had GAVE. Those with GAVE were more likely to have scleroderma renal crisis (SRC) (21% vs 3%; p < 0.01), positive anti-RNA polymerase III antibody (71% vs 19%; p < 0.01), nucleolar pattern of anti-nuclear antibody (ANA) (33% vs 11%; p=0.04), and negative ANA (<1:80 by immunofluorescence) (33% vs 11%; p=0.02). On multivariate analysis with multiple imputation, anti-RNA polymerase III positivity (OR 4.57; 95% CI (1.57 - 13.23), p < 0.01) and ANA negativity (OR 3.75; 95% CI (1.21 - 11.62), p=0.02) remained significantly associated with GAVE.

CONCLUSION

Positive anti-RNA polymerase III antibody and ANA negativity were significantly associated with GAVE. Further studies are necessary to determine whether patients with these autoantibody profiles should undergo screening endoscopies for GAVE.

Molecular characteristics and functional differences of anti-PM/Scl autoantibodies and two other distinct and unique supramolecular structures known as "EXOSOMES"

The term "exosome" has been applied to three distinct supramolecular entities, namely the PM/Scl autoantibodies or "RNA exosomes", transforming DNA fragments termed "DNA exosomes", and small size extracellular vesicles knows as "exosomes". Some of the molecular components of the "PM/Scl exosome complex" or "RNA exosome" are recognized by specific autoantibodies present in the serum from some Systemic Sclerosis (SSc), polymyositis (PM) and polymyositis SSc (PM/Scl) overlap syndrome patients. On the other hand, one of the most active focuses of laboratory investigation in the last decade has been the biogenesis and role of extracellular vesicles known as "exosomes". The remarkable ability of these "exosome" vesicles to alter the cellular phenotype following fusion with target cells and the release of their macromolecular cargo has revealed a possible role in the pathogenesis of numerous diseases, including malignant, inflammatory, and autoimmune disorders and may allow them to serve as theranostic agents for personalized and precision medicine. The indiscriminate use of the term "exosome" to refer to these three distinct molecular entities has engendered great confusion in the scientific literature. Here, we review the molecular characteristics and functional differences between the three molecular structures identified as "exosomes". Given the rapidly growing scientific interest in extravesicular exosomes, unless a solution is found the confusion in the literature resulting from the use of the term "exosomes" will markedly increase.

Autoantibody Biomarkers in Rheumatic Diseases

Autoantibodies encountered in patients with systemic rheumatic diseases bear clinical significance as a biomarker to help or predict diagnosis, clinical phenotypes, prognosis, and treatment decision-making. Furthermore, evidence has accumulated regarding the active involvement of disease-specific or disease-associated autoantibodies in the pathogenic process beyond simple association with the disease, and such knowledge has become essential for us to better understand the clinical value of autoantibodies as a biomarker. This review will focus on the current update on the autoantibodies of four rheumatic diseases (rheumatoid arthritis, myositis, systemic sclerosis, and anti-neutrophil cytoplasmic antibody associated vasculitis) where there has been a tremendous progress in our understanding on their biological effects and clinical use.

Anti-nuclear autoantibodies in systemic sclerosis : News and perspectives

Systemic sclerosis is a connective tissue disorder characterized by microvascular damage and excessive fibrosis of the skin and internal organs. One hallmark of the immunological abnormalities in systemic sclerosis is the presence of anti-nuclear antibodies, which are detected in more than 90% of patients with systemic sclerosis. Anti-centromere antibodies, anti-DNA topoisomerase I antibodies, and anti-RNA polymerase III antibodies are the predominant anti-nuclear antibodies found in systemic sclerosis patients. Other systemic sclerosis-related anti-nuclear antibodies include those targeted against U3 ribonucleoprotein, Th/To, U11/U12 ribonucleoprotein, and eukaryotic initiation factor 2B. Anti-U1 ribonucleoprotein, anti-Ku antibodies, anti-PM-Scl, and anti-RuvBL1/2 antibodies are associated with systemic sclerosis overlap syndrome. Anti-human upstream binding factor, anti-Ro52/TRIM21, anti-B23, and anti-centriole antibodies do not have specificity to systemic sclerosis, but are sometimes detected in sera from patients with systemic sclerosis. Identification of each systemic sclerosis-related antibody is useful to diagnose and predict organ involvement, since the particular type of systemic sclerosis-related antibodies is often predictive of clinical features, severity, and prognosis. The clinical phenotypes are largely influenced by ethnicity. Currently, an immunoprecipitation assay is necessary to detect most systemic sclerosis-related antibodies; therefore, the establishment of an easy, reliable, and simple screening system is warranted.

Anti-RNA polymerase III antibodies in patients with suspected and definite systemic sclerosis: Why and how to screen

Anti-RNA Polymerase III antibodies are the most frequent anti-nuclear antibodies in systemic sclerosis, after anti-centromere and anti-Topoisomerase I. Considering their specificity for systemic sclerosis, they have been included in 2013 American College of Rheumatology/European League Against Rheumatism classification criteria for systemic sclerosis. They were first identified in 1993 using an immunoprecipitation method; the subsequent diffusion of commercial assays, based on the enzyme-linked immunosorbent assay or multiplex line immunoblot techniques, has allowed an increasing number of systemic sclerosis patients to be tested for this autoantibody; nevertheless, the diffusion of this test in systemic sclerosis patients is probably still sub-optimal. Anti-RNA Polymerase III antibodies have been associated with important clinical manifestations: rapid and diffuse cutaneous involvement, joint contractures, scleroderma renal crisis, gastric antral vascular ectasia and malignancies synchronous to systemic sclerosis onset. Moreover, other possible clinical associations, including pulmonary hypertension, still need confirmation. Since the correct approach for screening for anti- RNA Polymerase III antibodies in patients with suspected or definite systemic sclerosis is still debated, possible strategies are proposed here. Moreover, issues that are still controversial are discussed, including the interpretation of multiple simultaneous positivity for anti-RNA Polymerase III antibodies and other autoantibodies in line immunoassay, and the possible relevance of anti-RNA Polymerase III antibodies titre.

Systemic sclerosis with anti-RNA polymerase III positivity following silicone breast implant rupture: possible role of B-cell depletion and implant removal in the treatment

Despite some case reports and small series of women with silicone breast implants (SBI) developing Systemic Sclerosis (SSc), no clear evidence of an association of SBI with SSc is available. However, SSc is characterized by clinical and immunological heterogeneity and autoantibodies are currently the best markers to stratify this heterogeneity of patients. Therefore, we have reviewed the literature for details of autoantibody characterization in reports of SSc associated with SBI. Moreover, the case of an anti-RNA polymerase III-positive SSc with rapid onset and progression, in which SBI rupture was found is described. This case may support a previous observation suggesting a possible role of SBI rupture as a trigger for anti-RNA polymerase III-positive SSc. This possible causal role may be reinforced by the observation that in our patient, despite immunosuppressive treatment, the disease progressed until SBI were removed, and reduction of anti-RNA polymerase III titer was obtained after rituximab treatment. This result may support data suggesting that B-cell depleting therapy may decrease specific autoantibody level in SSc patients, and that these changes are associated with disease improvement.

Malignancies in Patients with Anti-RNA Polymerase III Antibodies and Systemic Sclerosis: Analysis of the EULAR Scleroderma Trials and Research Cohort and Possible Recommendations for Screening

OBJECTIVE

To analyze the characteristics of anti-RNA polymerase III antibodies (anti-RNAP3)- positive patients with systemic sclerosis (SSc) in the European League Against Rheumatism Scleroderma Trials and Research group (EUSTAR) registry with a focus on the risk of cancer and the characteristics of malignancies, and the aim to provide guidelines about potential cancer screening in these patients.

METHODS

(1) Analysis of the EUSTAR database: 4986 patients with information on their anti-RNAP3 status were included. (2) Case-control study: additional retrospective data, including malignancy history, were queried in 13 participating EUSTAR centers; 158 anti-RNAP3+ cases were compared with 199 local anti-RNAP3- controls, matched for sex, cutaneous subset, disease duration, and age at SSc onset. (3) A Delphi exercise was performed by 82 experts to reach consensus for cancer screening in anti-RNAP3+ patients.

RESULTS

In the EUSTAR registry, anti-RNAP3 were associated in multivariable analysis with renal crisis and diffuse cutaneous involvement. In the case-control study, anti-RNAP3 were associated with gastric antral vascular ectasia, rapid progression of skin involvement, and malignancies concomitant to SSc onset (OR 7.38, 95% CI 1.61-33.8). When compared with other anti-RNAP3+ patients, those with concomitant malignancies had older age (p < 0.001) and more frequent diffuse cutaneous involvement (p = 0.008). The Delphi exercise highlighted the need for malignancy screening at the time of diagnosis for anti-RNAP3+ patients and tight followup in the following years.

CONCLUSION

Anti-RNAP3+ patients with SSc have a high risk of concomitant malignancy. These results have implications for clinical practice and suggest regular screening for cancer in anti-RNAP3+ patients.

Calcinosis is associated with digital ischaemia in systemic sclerosis-a longitudinal study

OBJECTIVE

To determine if ischaemia is a causal factor in the development of calcinosis in SSc.

METHODS

Patients with SSc were assessed yearly. Physicians reported the presence of calcinosis, digital ischaemia (digital ulcers, digital necrosis/gangrene, loss of digital pulp on any digits and/or auto- or surgical digital amputation) and nailfold capillary dropout assessed using a dermatoscope. The number of digits with digital ischaemia was used as an assessment of the severity of digital ischaemia. SSc specific antibodies were detected with a line immunoassay. Multiple logistic regression and Cox proportional hazards models were generated to determine associations between calcinosis, digital ischaemia and capillary dropout.

RESULTS

One thousand three hundred and five patients were included in this study, of whom 300 (23.0%) had calcinosis at study entry. In a cross-sectional multivariate analysis, at baseline, calcinosis was associated with digital ischaemia (odds ratio (OR) = 2.37, 95% CI: 1.66, 3.39), severity of ischaemia (OR = 1.12, 95% CI: 1.06, 1.18), capillary dropout (OR = 1.41, 95% CI: 1.05, 1.89), ACAs (OR = 1.68, 95% CI: 1.17, 2.43) and anti-RNA polymerase III antibodies (OR = 1.77, 95% CI: 1.08, 2.89). Current use of calcium channel blockers was inversely associated with the presence of calcinosis (OR = 0.70, 95% CI: 0.52, 0.96). Of the 805 patients with no calcinosis at study entry and at least one follow-up visit, 215 (26.7%) developed calcinosis during follow-up. Significant baseline predictors of the development of calcinosis in follow-up were digital ischaemia (hazard ratio (HR) = 1.82, 95% CI: 1.30, 2.54), capillary dropout (HR = 1.46, 95% CI: 1.08, 1.99), dcSSc (HR = 1.57, 95% CI: 1.11, 2.21), ACA (HR = 2.18, 95% CI: 1.50, 3.17) and anti-RNA polymerase III antibodies (HR = 2.58, 95% CI: 1.65, 4.04).

CONCLUSION

Ischaemia may play a role in the development of calcinosis in SSc.

Anti-centromere protein A antibodies in systemic sclerosis: Significance and origin

Systemic sclerosis (SSc) is systemic, autoimmune, connective tissue disorder characterized by vascular abnormalities, collagen deposition (fibrosis), and the production of autoantibodies to nuclear proteins. About 20%-40% of patients have antibodies to centromere protein (CENP)-A or -B. Despite the known association of anti-CENP antibodies with certain clinical features of SSc, the role of these antibodies in SSc physiopathology is still poorly understood. To better understand the clinical significance and origin of these antibodies, we and others have been studying the epitopic motifs (amino acid contact sites) on CENP-A with the aim of determining whether other proteins can prime or be targeted by them. Here, we review published and ongoing studies aimed at defining the fine specificity and origin of anti-CENP-A antibodies. We describe progress made in identifying the CENP-A epitopic motif amino acids, and the discovery of one of these motifs in forkhead box protein E3 (FOXE-3), a transcription factor previously studied only for its role in the development of lens fiber cells. Moreover, we discuss preliminary evidence for a possible role of FOXE-3 in SSc pathogenesis and for the association of different subsets of anti-CENP-A antibodies, heterogeneously expressed among SSc patients, with some clinical correlates.

Update on biomarkers in systemic sclerosis: tools for diagnosis and treatment

Systemic sclerosis (SSc) is a complex autoimmune disease in which immune activation, vasculopathy, and extensive fibrosis of the skin and internal organs are among the principal features. SSc is a heterogeneous disease with varying manifestations and clinical outcomes. Currently, patients’ clinical evaluation often relies on subjective measures, non-quantitative methods, or requires invasive procedures as markers able to predict disease trajectory or response to therapy are lacking. Therefore, current research is focusing on the discovery of useful biomarkers reflecting ongoing inflammatory or fibrotic activity in the skin and internal organs, as well as being predictive of future disease course. Recently, remarkable progress has been made towards a better understanding of numerous mechanisms involved in the pathogenesis of SSc. This has opened new possibilities for the development of novel biomarkers and therapy. However, current proposed biomarkers that could reliably describe various aspects of SSc still require further investigation. This review will summarize studies describing the commonly used and validated biomarkers, the newly emerging and promising SSc biomarkers identified to date, and consideration of future directions in this field.

Intracellular sensing of viral DNA by the innate immune system

Recent years have seen a great advance in knowledge of how a host senses infection. Nucleic acids, as a common denominator to all pathogens, are at the centre of several of the sensing pathways, especially those involved with the recognition of viruses. In this review we discuss the current knowledge on how intracellular DNA is sensed by the mammalian host.

Current status of systemic sclerosis biomarkers: applications for diagnosis, management and drug development

Systemic sclerosis (SSc) is a clinically heterogeneous orphan disease of unknown etiology and no effective therapy. It is characterized by protean manifestations, an unpredictable disease course and variable outcomes. Clinical manifestations reflect underlying autoimmunity, small vessel vasculopathy and progressive multi-organ fibrosis. Predicting disease progression, pattern and severity of complications and response to therapy in SSc remain major challenges both for the management of patients and for the development of effective disease-modifying therapies. This review summarizes contemporary understanding of novel and emerging biomarkers for SSc. We focus on the development of new classification criteria, the utility of SSc-specific autoantibodies as diagnostic and prognostic markers, and on biomarkers for skin and lung involvement. Finally, we review genome-wide expression analysis as a tool to predict therapeutic responses. We anticipate that the development, validation and application of these biomarkers, singly or more likely in combination, will have a transformative impact in SSc, informing early diagnosis, classification and management, as well as the design, execution and interpretation of clinical trials of novel therapeutic agents.

Agonistic anti-ICAM-1 antibodies in scleroderma: activation of endothelial pro-inflammatory cascades

Background

Scleroderma (SSc) is a complex autoimmune disorder that can be characterised by the presence 2of circulating autoantibodies to nuclear, cytoplasmic and cell surface antigens. In particular antibodies directed against endothelial cell antigens (anti-endothelial cell antibodies; AECA) have been detected.

ICAM-1 is an adhesion molecule expressed on the surface of human endothelial cells. We have previously shown that cross-linking ICAM-1 with monoclonal antibodies leads to pro-inflammatory activation of human endothelial and vascular smooth muscle cells and that cardiac transplant recipients with transplant associated vasculopathy make antibodies directed against ICAM-1.

Objectives

To determine whether SSc patients make antibodies directed against ICAM-1 and whether these antibodies induce pro-inflammatory activation of human endothelial cells in vitro.

Methods

Using recombinant ICAM-1 as capture antigen, an ELISA was developed to measure ICAM-1 antibodies in sera from SSc patients. Antibodies were purified using ICAM-1 micro-affinity columns. HUVEC were incubated with purified anti-ICAM-1 antibodies and generation of reactive oxygen species, and expression of VCAM-1 was measured.

Results

Significantly elevated levels of anti-ICAM-1 antibodies were detected in patients with diffuse (dSSc; 10/31 32%) or limited (lSSc; 14/36 39%) scleroderma. Cross-linking of HUVEC with purified anti-ICAM-1 antibodies caused a significant increase in ROS production (2.471 ± 0.408 fold increase above untreated after 150 min p < 0.001), and significant increase in VCAM-1 expression (10.6 ± 1.77% vs 4.12 ± 1.33%, p < 0.01).

Conclusion

AECA from SSc patients target specific endothelial antigens including ICAM-1, and cause pro-inflammatory activation of human endothelial cells, suggesting that they are not only a marker of disease but that they contribute to its progression.

Progression of Nailfold Microvascular Damage and Antinuclear Antibody Pattern in Systemic Sclerosis

Objective.

This study evaluates possible correlations between the pattern of antinuclear antibodies (ANA) on indirect immunofluorescence (IIF) testing and nailfold microangiopathy stage (early, active, and late stage) in systemic sclerosis (SSc). Patients with SSc were followed prospectively to monitor progression of microvascular damage.

Methods.

The ANA pattern on IIF was searched in 42 patients with SSc showing an early pattern of nailfold microangiopathy at baseline, and was followed using nailfold videocapillaroscopy (NVC) for a median time of 91 months.

Results.

Among patients whose microangiopathy showed a rapid progression from early to late pattern on NVC, the IIF pattern was fine-speckled + nucleolar (Scl-70+) in 44%, centromeric in 33%, nucleolar in 11%, and homogeneous in 11% of patients with SSc. Antitopoisomerase I antibodies were significantly more frequent (57%) in patients with late pattern of microangiopathy on NVC. The median time of progression from early to active disease was significantly lower in patients with both fine-speckled + nucleolar and nucleolar ANA positivity. The severity of microangiopathy was higher in patients with the nucleolar pattern on IIF. Patients already showing a slight reduction of capillary number at baseline were likely to have either the nucleolar or the fine-speckled + nucleolar pattern on IIF. Of note, 37% of patients still showing the early microangiopathy pattern on NVC at the end of the followup were ANA-negative.

Conclusion.

ANA-negative patients with SSc display a slower progression of nailfold microangiopathy characterized by the early pattern on NVC. Progression to the late NVC pattern (more advanced stage of microvascular damage) seems to be associated with a different autoantibody pattern on IIF (fine-speckled + nucleolar pattern being the most prevalent).

DNA-PK is a DNA sensor for IRF-3-dependent innate immunity

Innate immunity is the first immunological defence against pathogens. During virus infection detection of nucleic acids is crucial for the inflammatory response. Here we identify DNA-dependent protein kinase (DNA-PK) as a DNA sensor that activates innate immunity. We show that DNA-PK acts as a pattern recognition receptor, binding cytoplasmic DNA and triggering the transcription of type I interferon (IFN), cytokine and chemokine genes in a manner dependent on IFN regulatory factor 3 (IRF-3), TANK-binding kinase 1 (TBK1) and stimulator of interferon genes (STING). Both cells and mice lacking DNA-PKcs show attenuated cytokine responses to both DNA and DNA viruses but not to RNA or RNA virus infection. DNA-PK has well-established functions in the DNA repair and V(D)J recombination, hence loss of DNA-PK leads to severe combined immunodeficiency (SCID). However, we now define a novel anti-microbial function for DNA-PK, a finding with implications for host defence, vaccine development and autoimmunity.

DOI:http://dx.doi.org/10.7554/eLife.00047.001

For multicellular organisms, the innate immune system is the first immunological defence against infection, rapidly recognizing and responding to the presence of any pathogen. Many different cell types contribute to the innate immunity, including fibroblasts, epithelial cells, dendritic cells and macrophages. Once alerted to injury or infection, these cells release proteins called cytokines, interferons and chemokines into the blood or directly into tissue. These proteins act as messengers and interact with receptors on the surfaces of other cells in the immune system, stimulating them to join the battle against the infection.

Detecting nucleic acids such as DNA is an important part of recognizing pathogens and infectious agents, particularly viruses, and activating the innate immune system. However, while the presence of DNA in the cytoplasm is known to initiate an innate immune response, we do not fully understand how this foreign DNA is sensed, or how the innate immune system is activated once foreign DNA has been detected.

Here Ferguson et al. report that a well-known complex of three proteins, collectively called DNA-dependent protein kinase, is able to activate an innate immune response when it detects foreign DNA. This enzyme, called DNA-PK for short, is best known for its ability to repair broken DNA inside the nucleus. Now Ferguson et al. have found that it is also present at high levels within fibroblasts, cells that are often primary targets of viral infection, and they go on to explain how the detection of DNA by DNA-PK triggers a sequence of events that leads to the innate immune response being activated. These events include the transcription of type I interferon, chemokines and cytokines in a manner that depends on the presence IRF-3, a transcription factor that has a central role in the response of the immune system to viral infection.

By identifying a role for DNA-PK in the cytoplasm as a DNA sensor, the work of Ferguson et al. increases our understanding of innate immunity. It may also, in the future, lead to an improved understanding of autoimmunity, and might also assist in the development of more immunogenic vaccines based on DNA or microbes that contain DNA.

DOI:http://dx.doi.org/10.7554/eLife.00047.002

Coexistence of anti-RNA polymerase III and anti-U1RNP antibodies in patients with systemic lupus erythematosus: two cases without features of scleroderma

Anti-RNA polymerase III (RNAP III) antibodies are highly specific for scleroderma (SSc) and associated with diffuse SSc and renal crisis. Coexistence of anti-RNAP III and other SSc autoantibodies is rarely documented. We report three cases with coexisting anti-RNAP III and anti-U1RNP. Autoantibodies in 3829 sera from rheumatology clinics were screened by immunoprecipitation. Anti-RNAP III-positive sera were also examined by immunofluorescence and anti-RNAP III ELISA. In total, 35 anti-RNAP III-positive sera were identified by immunoprecipitation, in which three had coexisting anti-U1RNP. All three were anti-RNAP III ELISA positive. Two had anti-RNAP I dominant (vs. RNAP III) reactivity and showed strong nucleolar staining. A case with anti-U1/U2RNP (U2RNP dominant) had systemic lupus erythematosus (SLE)-SSc overlap syndrome; however, the remaining two cases had SLE without signs of SSc. All three cases of anti-RNAP III + U1RNP fulfilled ACR SLE criteria but none in the group with anti-RNAP III alone (p = 0.0002). In contrast, only one case in the former group had sclerodermatous skin changes and Raynaud's phenomenon, vs. 92% with scleroderma in the latter (p < 0.05). Although anti-RNAP III is highly specific for SSc, cases with coexisting anti-U1RNP are not so uncommon among anti-RNAP III positives (8%, 3/35) and may be SLE without features of SSc.

Atypical clinical presentation of a subset of patients with anti-RNA polymerase III--non-scleroderma cases associated with dominant RNA polymerase I reactivity and nucleolar staining

Introduction

Anti-RNA polymerase III (RNAP III) antibodies are highly specific markers of scleroderma (systemic sclerosis, SSc) and associated with a rapidly progressing subset of SSc. The clinical presentation of anti-RNAP III positive patients, onset of Raynaud's phenomenon (RP) and SSc in unselected patients in a rheumatology clinic were evaluated.

Methods

Autoantibodies in sera from 1,966 unselected patients (including 434 systemic lupus erythematosus (SLE), 119 SSc, 85 polymyositis/dermatomyositis (PM/DM)) in a rheumatology clinic were screened by radioimmunoprecipitation. Anti-RNAP III positive sera were also tested by immunofluorescence antinuclear antibodies and anti-RNAP III ELISA. Medical records of anti-RNAP III positive patients were reviewed.

Results

Among 21 anti-RNAP III positive patients, 16 met the American College of Rheumatology (ACR) SSc criteria at the initial visit but 5 did not; diagnoses were vasculitis, early polyarthritis, renal failure with RP, interstitial lung disease, and Sjögren's syndrome. The first two patients developed rapidly progressive diffuse SSc. An additional case presented with diffuse scleroderma without RP and RP developed two years later. Anti-RNAP III antibodies in these 6 cases of atypical clinical presentation were compared with those in 15 cases of typical (SSc with RP) cases. Anti-RNAP III levels by ELISA were lower in the former group (P = 0.04 by Mann-Whitney test) and 3 of 6 were negative versus only 1 of 15 negative in the latter (P < 0.05 by Fisher's exact test). Three cases of non-SSc anti-RNAP III positive patients had predominant reactivity with RNAP I with weak RNAP III reactivity and had a strong nucleolar staining. Three anti-RNAP III patients, who did not have RP at the initial visit, developed RP months later. Scleroderma developed prior to RP in 5 out of 16 (31%) in the anti-RNAP III group, but this was rare in patients with other autoantibodies. The interval between the onset of RP to scleroderma was short in anti-RNAP III positive patients.

Conclusions

Anti-RNAP III antibodies are highly specific for SSc; however, a subset of anti-RNAP III positive patients do not present as typical SSc. The interval between RP and scleroderma in this group is short, and 31% of patients developed scleroderma prior to RP in this group. Anti-RNAP III positive patients may not present as typical SSc and detecting anti-RNAP III may have predictive value.

Gender and ethnicity differences in the prevalence of scleroderma-related autoantibodies

Autoantibodies to topoisomerase I (topo I), RNA polymerase III (RNAPIII), centromere, U3RNP/fibrillarin, Th, PM-Scl, and U1RNP found in scleroderma (SSc) are associated with unique clinical subsets. The effects of race and gender on autoantibody prevalence and clinical manifestations were examined. Autoantibodies in sera from 105 SSc (include 75 Caucasian, 24 African-American, 6 others; 89 females and 16 males) were analyzed by immunofluorescence and immunoprecipitation. Clinical information was from database. SSc-related autoantibodies seldom coexist except for anti-topo I and anti-U1RNP. Anti-topo I (35% vs 15%), anti-U3RNP (30% vs 3%, p = 0.0005), and anti-U1RNP (30% vs 13%) were more common in African-Americans vs Caucasians. Anti-centromere (17%) and anti-PM-Scl (only in 8% of female) were found only in Caucasians. In race/gender combination, all three African-American males had anti-topo I (p = 0.04). Anti-U3RNP (35% vs 3%, p = 0.0005) and anti-U1RNP were common in African-American females. In African-American, all nucleolar dominant staining sera had anti-U3RNP; nuclear pattern was topo I (50%), U1RNP (19%), and RNAPIII (13%). In Caucasian, nucleolar was anti-Th (43%) and PM-Scl (29%); nuclear pattern was RNAPIII (29%), topo I (24%), and U1RNP (18%). Anti-topo I, anti-RNAPIII, and anti-U3RNP were associated with diffuse SSc while anti-centromere, anti-Th, and anti-U1 with limited disease. Proximal scleroderma was less common in African-American with anti-topo I (38% vs 91% in Caucasian, p = 0.04). The production of SSc-related autoantibodies is gender and race dependent, and this can be highly relevant in understanding their clinical significance.

Malignancies in Italian patients with systemic sclerosis positive for anti-RNA polymerase III antibodies

OBJECTIVE

To evaluate the frequency of malignancies in Italian patients with systemic sclerosis (SSc) and anti-RNA polymerase III (RNAP III), antitopoisomerase I (topo I), or anticentromere antibodies (ACA); and to characterize the temporal relationship between the 2 diseases, in order to confirm data suggesting a close temporal relationship between the onset of SSc and malignancy in American patients with anti-RNAP III antibodies.

METHODS

From a cohort of 466 consecutive SSc patients, 360 Italians with isolated positivity for anti-RNAP III (n = 16), anti-topo I (n = 101), or ACA (n = 243) were identified. Malignancy cases were divided according to their relationship with SSc onset into 3 categories: preceding, synchronous with, or metachronous to the onset of SSc (diagnosed more than 6 months before; 6 months before to 12 months after; and more than 12 months after onset of SSc, respectively).

RESULTS

Malignancies were more frequent in the anti-RNAP III group (7/16 patients), than in the anti-topo I (11/101) and ACA groups (21/243) (p < 0.001). This difference was accounted for by the number of patients with cancer synchronous to the onset of SSc (3/16 in the anti-RNAP III group vs 0/101 in the anti-topo I and 1/243 in the ACA group; p < 0.001), whereas neither the number of malignancies preceding nor those metachronous to the onset of SSc was significantly different between the groups.

CONCLUSION

In a cohort of Italian patients with SSc we observed a significant association between malignancies synchronous to SSc onset and positivity for anti-RNAP III antibodies, similar to that described in American patients with SSc.

Risk factors and prediction of long-term outcome in primary biliary cirrhosis

The natural history of the disease varies greatly among individual patients with primary biliary cirrhosis (PBC). Some patients live long without any symptoms while other patients present jaundice and develop hepatic failure in early phases of the disease. Previous studies showed that the natural course of PBC is altered by the use of ursodeoxy cholic acid (UDCA). In this review we discuss variation in the natural course of the disease and it's alteration by UDCA, and risk factors that predict disease progression. Based on clinical observations, there are three types of clinical evolution in PBC: 1) minimal to slow progression over several years; 2) rapid progression to jaundice and hepatic failure, and 3) progression to portal hypertension without developing deep jaundice. Notably, based on our analyses accelerated progression to jaundice and liver failure are reflected by a sustained serologic presence of anti-gp210 antibodies whereas patients with portal hypertension in the absence of jaundice have anti-centromere autoantibodies. These observations highlight the clinical importance of antinuclear antibody analysis in patients with PBC.

Anti-Th/To Are Common Antinucleolar Autoantibodies in Italian Patients with Scleroderma

Objective.

Patients with scleroderma (systemic sclerosis; SSc) can be classified into subsets based on autoantibody profile and clinical features. Specificities such as anti-Th/To and anti-fibrillarin (U3RNP) are detectable mainly by immunoprecipitation (IP), which is not widely used in clinical laboratories. We examined the autoantibody profiles and clinical manifestations in a cohort of Italian patients with SSc, focusing on anti-Th/To and anticentromere (ACA) antibodies, associated with limited cutaneous SSc (lcSSc).

Methods.

Sera from 216 consecutive patients with SSc were tested for ACA (by indirect immunofluorescence), antitopoisomerase I (topo I; by counterimmunoelectrophoresis), and anti-RNA polymerase III (RNAPIII; by ELISA). Forty-one sera negative for these specificities were tested by IP analysis of proteins (35S-methionine labeled K562 cell extract) and RNA (silver staining).

Results.

Among 216 SSc patients analyzed, anti-topo I, ACA, and anti-RNAPIII were detected in 38% (81/216), 31% (67/216) and 7% (15/216), respectively. Among 41 sera negative for ACA, anti-topo I, and anti-RNAPIII and which were tested by IP, 14 were nucleolar stain-positive. Eight out of 14 (57%) showed anti-Th/To reactivity, but no anti-U3RNP was found. In comparison with ACA-positive patients, anti-Th/To-positive patients were younger (p = 0.0046) and more commonly were male (p = 0.0006). All 8 anti-Th/To-positive and all but one ACA-positive patients had lcSSc. Interstitial lung disease (ILD) and pericarditis were more frequent in anti-Th/To-positive patients.

Conclusion.

Anti-Th/To are common in antinucleolar antibody-positive Italian patients with SSc. Anti-Th/To and ACA patients had lcSSc, with excellent prognosis. The anti-Th/To group had frequent pericarditis and ILD, although impairment of pulmonary function appeared mild.