Clinical and serological associations with anti-RNA polymerase antibodies in systemic sclerosis

Neurological, cardiac, musculoskeletal, and renal manifestations of scleroderma along with insights into its genetics, pathophysiology, diagnostic, and therapeutic updates

Background

Scleroderma, also referred to as systemic sclerosis, is a multifaceted autoimmune condition characterized by abnormal fibrosis and impaired vascular function. Pathologically, it encompasses the persistent presence of inflammation, abnormal collagen buildup, and restructuring of blood vessels in various organs, resulting in a wide range of clinical symptoms. This review incorporates the most recent scientific literature on scleroderma, with a particular emphasis on its pathophysiology, clinical manifestations, diagnostic approaches, and treatment options.

Methodology

A comprehensive investigation was carried out on numerous databases, such as PubMed, MEDLINE, Scopus, Web of Science, and Google Scholar, to collect pertinent studies covering diverse facets of scleroderma research.

Results

Scleroderma presents with a range of systemic manifestations, such as interstitial lung disease, gastrointestinal dysmotility, Raynaud's phenomenon, pulmonary arterial hypertension, renal complications, neurological symptoms, and cardiac abnormalities. Serological markers, such as antinuclear antibodies, anti-centromere antibodies, and anti-topoisomerase antibodies, are important for classifying diseases and predicting their outcomes.

Discussion

The precise identification of scleroderma is crucial for promptly and correctly implementing effective treatment plans. Treatment approaches aim to improve symptoms, reduce complications, and slow down the progression of the disease. An integrated approach that combines pharmacological agents, including immunosuppressants, endothelin receptor antagonists, and prostanoids, with nonpharmacological interventions such as physical and occupational therapy is essential for maximizing patient care.

Conclusion

Through the clarification of existing gaps in knowledge and identification of emerging trends, our goal is to improve the accuracy of diagnosis, enhance the effectiveness of therapeutic interventions, and ultimately enhance the overall quality of life for individuals suffering from scleroderma. Ongoing cooperation and creative research are necessary to advance the field and achieve improved patient outcomes and new therapeutic discoveries.

[Systemic sclerosis]

BACKGROUND

Systemic sclerosis (SSc) is a very heterogeneous, chronic, rare, but socioeconomically important disease with a severe disease course and severe impairment of the quality of life of affected patients.

OBJECTIVES

Overview of the current state of research on the pathogenesis, diagnosis and therapy of SSc.

METHODS

A literature search was performed.

RESULTS

The pathogenesis of SSc is not fully understood. ACR/EULAR criteria allow the diagnosis of early forms of SSc. Classification into limited cutaneous SSc and diffuse cutaneous SSc is of prognostic and therapeutic relevance. New organ-specific treatment options for SSc have led to improved quality of life and prognosis.

The Autoantibody Array Assay: A Novel Autoantibody Detection Method

Systemic sclerosis (SSc) and dermatomyositis (DM) are autoimmune collagen diseases. Specific autoantibodies are known to be involved in their pathogeneses, each presenting with a different clinical manifestation. Although immunoprecipitation is the gold standard method for detecting autoantibodies, it is difficult to perform in all cases owing to the use of radioisotopes. In this study, we developed a new detection method for SSc and DM autoantibodies (A-cube) using cell-free protein synthesis and examined its validity. Proteins were synthesized using wheat germ cell-free protein synthesis. A total of 100 cases of SSc, 50 cases of DM, and 82 healthy controls were examined. The validity of the method was examined by a comparison with existing test results. Anti-centromere antibody, anti-topoisomerase I antibody, anti-RNA polymerase III antibody, anti-U1RNP anti-body, anti-Jo-1 antibody, anti-TIF1γ antibody, anti-Mi-2 antibody, and anti-ARS antibody were tested for. The results suggested that A-cube is comparable with existing testing methods or has a high sensitivity or specificity. In addition, there was a case in which the diagnosis was reconsidered using the A-cube. The quality of the A-cube was ensured, and its usefulness for a comprehensive analysis was demonstrated. The A-cube can therefore contribute to the clinical assessment and treatment of SSc and DM.

Approach to Systemic Sclerosis Patient Assessment

Systemic sclerosis (SSc) is a heterogeneous disease comprising of a wide spectrum of ages of onset, sex-based differences, ethnic variations, disease manifestations, differential serologic profiles, and variable response to therapy resulting in reduced health-related quality of life, disability, and survival. The ability to subset groups of patients with SSc can assist with refining the diagnosis, guide appropriate monitoring, inform aggressiveness of immunosuppression, and predict prognosis. The ability to subset patients with SSc has several important practical implications for patient care.

Autoantibodies as Biomarker and Therapeutic Target in Systemic Sclerosis

Systemic sclerosis (SSc) is a rare connective tissue disorder characterized by immune dysregulation evoking the pathophysiological triad of inflammation, fibrosis and vasculopathy. In SSc, several alterations in the B-cell compartment have been described, leading to polyclonal B-cell hyperreactivity, hypergammaglobulinemia and autoantibody production. Autoreactive B cells and autoantibodies promote and maintain pathologic mechanisms. In addition, autoantibodies in SSc are important biomarkers for predicting clinical phenotype and disease progression. Autoreactive B cells and autoantibodies represent potentially promising targets for therapeutic approaches including B-cell-targeting therapies, as well as strategies for unselective and selective removal of autoantibodies. In this review, we present mechanisms of the innate immune system leading to the generation of autoantibodies, alterations of the B-cell compartment in SSc, autoantibodies as biomarkers and autoantibody-mediated pathologies in SSc as well as potential therapeutic approaches to target these.

Systematic Analysis of the Literature in Search of Defining Systemic Sclerosis Subsets

OBJECTIVE

Systemic sclerosis (SSc) is a multisystem disease with heterogeneity in presentation and prognosis.An international collaboration to develop new SSc subset criteria is underway. Our objectives were to identify systems of SSc subset classification and synthesize novel concepts to inform development of new criteria.

METHODS

Medline, Cochrane MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, EMBASE, and Web of Science were searched from their inceptions to December 2019 for studies related to SSc subclassification, limited to humans and without language or sample size restrictions.

RESULTS

Of 5686 citations, 102 studies reported original data on SSc subsets. Subset classification systems relied on extent of skin involvement and/or SSc-specific autoantibodies (n = 61), nailfold capillary patterns (n = 29), and molecular, genomic, and cellular patterns (n = 12). While some systems of subset classification confer prognostic value for clinical phenotype, severity, and mortality, only subsetting by gene expression signatures in tissue samples has been associated with response to therapy.

CONCLUSION

Subsetting on extent of skin involvement remains important. Novel disease attributes including SSc-specific autoantibodies, nailfold capillary patterns, and tissue gene expression signatures have been proposed as innovative means of SSc subsetting.

Antinuclear Antibody Tests

The presence of antinuclear antibodies (ANAs), which include autoantibodies to extractable nuclear antigens (ENAs), in the sera of patients with connective tissue diseases provides useful immunologic and pathophysiologic insight into the nature of their disease. This article discusses the most commonly used diagnostic modalities for detecting and quantitating the presence of ANA: indirect immunofluorescence assay, enzyme-linked immunosorbent assay, and multiplex bead technology, which serve as useful screening tests. We also review testing for autoantibodies to ENAs, which are often helpful to confirm the diagnosis of a specific connective tissue disease.

Relevance of clinical and autoantibody profiles in systemic sclerosis among Thais

OBJECTIVE

Autoantibody profiles in systemic sclerosis (SSc) and their relative clinical association vary between studies. The rate for being anti-topoisomerase-I (ATA) positive and the association with diffuse cutaneous the SSc subset (dcSSc) is higher among Thais than among Caucasians. The objective was to evaluate the relevance of clinical presentation, namely being positive for one or more autoantibodies among Thai SSc patients.

METHOD

A retrospective, cohort study was performed among SSc patients over 18 years of age at Srinagarind Hospital, Khon Kaen University, Thailand, during January 2006 to December 2013. Autoantibodies comprising 13 SSc-specific antigens were evaluated using the EUROIMMUN AG (Lübeck, Germany) in order to define their clinical association(s).

RESULTS

Two hundred and eighty-five scleroderma patients (200 female; 85 male) were included. The majority (66.7%) were dcSSc subset. ATA was the most common antibody profile in our patients (231 cases; 81.1%), followed by anti-Ro 52 (87 cases; 30.5%). Eleven of our patients (3.9%) were negative for all antibody profiles and 44 cases (15.4%) were negative for ATA and anti-centromere antibody (anti-CENP). Almost 40% (112 cases) were positive for at least two autoantibodies. There was an association between the presence of ATA and hand deformity (odds ratio [OR] 3.94; 95% CI 1.12-13.84), anti-CENP and hand deformity (OR 0.20; 95% CI 0.02-0.90), anti-Ku and scleroderma-polymyositis overlap syndrome (OR 6.58; 95% CI 2.16-19.39) and the absence of both ATA and anti-CENP with female sex (OR 2.90; 95% CI 1.12-7.51), limited cutaneous SSc subset (OR 2.70; 95% CI 1.30-5.55) and scleroderma-polymyositis overlap syndrome (OR 2.53; 95% CI 1.04-6.16). Neither ATA nor anti-CENP were associated with the SSc subset.

CONCLUSIONS

ATA and anti-CENP were not helpful in differentiating the SSc subset in Thai SSc patients, albeit they were good for predicting hand function. Coexisting ATA and anti-CENP negativity were associated with less extensive skin tightness and SSc overlap syndrome.

Immune-Mediated Heart Disease

The heart involvement in systemic autoimmune diseases represents a growing burden for patients and health systems. Cardiac function can be impaired as a consequence of systemic conditions and manifests with threatening clinical pictures or chronic myocardial damage. Direct injuries are mediated by the presence of inflammatory infiltrate which, even though unusual, is one of the most danger manifestations requiring prompt recognition and treatment. On the other hand, a not well-managed inflammatory status leads to accelerated atherosclerosis that precipitates ischemic disease. All cardiac structures may be damaged with different grades of intensity; moreover, lesions can appear simultaneously or more frequently at a short distance from each other leading to the onset of varied clinical pictures. The pathogenesis of heart damages in systemic autoimmune conditions is not yet completely understood for the great part of situations, even if several mechanisms have been investigated. The principal biochemical circuits refer to the damaging role of autoantibodies on cardiac tissues and the precipitation of immune complexes on endocardium. These events are finally responsible of inflammatory infiltration which leads to subsequent worsening of the previous damage. For these reasons, it appears of paramount importance a regular and deepened cardiovascular assessment to prevent a progressive evolution toward heart failure in patient affected by autoimmune diseases.

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.

A cross-sectional study of autoantibody profiles in the Waikato systemic sclerosis cohort, New Zealand

The autoantibody profiles in New Zealand systemic sclerosis patients have not previously been reported. The aim of this study was to evaluate the autoantibody profiles of patients in the Waikato Hospital Systemic Sclerosis Clinic cohort. The EUROLINE (IgG) Systemic Sclerosis panel test kit (which tests for Scl-70, CENP-A, CENP-B, RP11, RP155, Fib, NOR90, Th/To, PM100, PM75, Ku, PDGFR and Ro-52) was selected for the purpose of this study. All patients attending the Waikato Hospital Systemic Sclerosis clinic were invited to participate. These patients were categorised by systemic sclerosis subtypes [1]. Results were compared with previously published data, including the EUSTAR database. Sixty patients (56 female) were recruited, with a median age of 61 years (range 29-81 years). Forty-one had limited cutaneous systemic sclerosis (lcSSc). Of these lcSSc patients, 31 (75.6%) were positive for CENP-A and CENP-B (anti-centromere) antibodies, 12 (29.3%) for Ro-52 antibodies, 5 (12.2%) for RP11 and RP155, 4 (9.8%) for Scl-70 and 1 (2.4%) each for anti-Fib and Th/To antibodies. Fifteen patients had diffuse cutaneous systemic sclerosis (dcSSc), of which 7 patients (47.6%) were positive for RP11 and RP155, 4 (26.7%) for Scl-70. Three dcSSc patients did not have either of these two major antibodies, but of these 15 dcSSc patients, 4 patients (26.7%) were positive also for Ro-52, 2 (13.3%) for anti-Ku, and 1 (6.7%) each for anti-Fib and NOR90. Four patients had overlap syndrome (OLS), 1 had CENP-A and CENP-B antibodies, 1 had Ro-52 autoantibodies 1 had anti-Ku antibodies. Three patients had no autoantibodies. This is the first study to look at the autoantibody profile of SSc patients in New Zealand. A higher prevalence of antibodies against centromere and RNA polymerase III was demonstrated in our group compared with the EUSTAR database suggesting that antibody prevalence may vary geographically.

Clinical differences between Thai systemic sclerosis patients with positive versus negative anti-topoisomerase I

BACKGROUND

Anti-topoisomerase I antibody (ATA) carries an increased risk of systemic sclerosis (SSc) internal organ involvement. There have been no published comparisons of the clinical characteristics of patients positive and negative for ATA in Thailand, where the positive rate for ATA is higher than among Caucasians.

OBJECTIVE

To define the clinical differences between SSc, positive versus negative, for ATA.

METHODS

A retrospective cohort study was performed among SSc patients over 18 at Srinagarind Hospital, Khon Kaen University, Thailand, during January 2006-December 2013. SSc-overlap syndrome was excluded.

RESULTS

Two hundred and ninety-four SSc patients were included (female : male 2.5 : 1). The majority (68.6%) were the diffuse cutaneous SSc subset (dcSSc). ATA was positive in 252 patients (85.7%), among whom 71.7% had dcSSc and 28.2% limited cutaneous SSc (lcSSc). Using a multivariate analysis, hand deformity had a significantly positive association with ATA (odds ratio [OR] 7.01; 95% CI 1.02-48.69), whereas being anti-centromere (ACA) positive had a negative association (OR 0.17; 95% CI 0.03-0.92). After doing a subgroup analysis of the SSc subset, the median duration of disease at time of pulmonary fibrosis detection among ATA positive dcSSc was significantly shorter than the ATA negative group (1.05 vs. 6.77 years, P = 0.01). Raynaud's phenomenon (RP) at onset was significantly more frequent in lcSSc sufferers who were ATA negative than those who were ATA positive (90.5% vs. 56.9%, P = 0.005).

CONCLUSIONS

A high prevalence of ATA positivity was found among Thai SSc patients and this was associated with a high frequency of hand deformity, ACA negativity, a short duration of pulmonary fibrosis in dcSSc and a lower frequency of RP in lcSSc.

Impact of Age and Autoantibody Status on the Gene Expression of Scleroderma Fibroblasts in Response to Silica Stimulation

Environmental factors are believed to play an important role in the pathogenesis of systemic sclerosis (SSc). Silica exposure has been implicated as potentially hazardous in epidemiological studies of SSc. It can activate fibroblasts to express profibrotic genes at certain conditions. The aim of this study is to examine whether the fibroblasts of SSc patients respond to silica particles with specific gene expressions differentially from normal control fibroblasts. The fibroblasts obtained from skin biopsies of 96 SSc patients and 104 controls were examined. Silica particles were used to perturb the cultures of the fibroblasts in time-course and dose-response assays. The transcript levels of COLI A2, COL3A1, MMP1, MMP3, TIMP3 and CTGF genes of the fibroblasts were measured with quantitative RT-PCR. The results showed that the expressions of all six genes in SSc fibroblasts under silica perturbation appeared significantly different from normal control fibroblasts. In age stratified analysis, compared to control fibroblasts, SSc fibroblasts from patients at age 30–40 years and 50–60 years displayed significantly decreased expressions of MMP1 gene in all dosage assays and increased expression of COL3A1 genes started at low dosages perturbation of silica particles, respectively. In autoantibody stratified analysis, specific gene expression patterns were significantly associated with autoantibody-subgroups of fibroblasts. A common feature of SSc fibroblasts was unstable and a wide range of gene expression changes in response to silica perturbation. Our studies may suggest an altered intrinsic dynamic control in SSc fibroblasts. In addition, sensitivity and specificity of SSc fibroblasts to potentially hazardous environmental trigger is age and autoantibody-subgroup-dependent. The fibroblasts of SSc patients at age 30–60 years may be more sensitive to silica perturbation toward a profibrotic gene expression.

A new immunoprecipitation-real time quantitative PCR assay for anti-Th/To and anti-U3RNP antibody detection in systemic sclerosis

INTRODUCTION

Classic anti-nucleolar antibodies anti-Th/To and U3 ribonucleoprotein (-U3RNP) can help in the diagnosis, prediction of organ involvement and prognosis in systemic sclerosis (SSc); however, no validated commercial assay is available. We aimed at establishing a novel quantitative real time PCR (qPCR) method to detect these antibodies.

METHODS

Standard immunoprecipitation (IP) was performed using K562 cell extract and RNA components were extracted. cDNA was reverse transcribed from RNA components and Th RNA and U3 RNA were detected by qPCR using custom primers. Cycle threshold (Ct) values were compared in a titration experiment to determine the assay efficacy. The new assay was evaluated by testing 22 anti-Th/To and 12 anti-U3RNP positive samples in addition to 88 controls, and the results were compared with IP as a gold standard.

RESULTS

By testing serial 1:8 dilutions of cell lysate as the substrate in the IP step, RNA extracted after IP, and its derived cDNA, linear dose response curves were noted for both anti-Th/To and -U3RNP. With every dilution, Ct values changed approximately three as expected, reflecting the eight-fold difference of cDNA. The Ct difference between positive and negative samples was 8 to 13, which was similar throughout the dilutions. In the specificity analysis, the Ct values of positive samples were clearly different from the negative groups and the results by qPCR had a near perfect correlation with IP.

CONCLUSIONS

Our new method readily detects these two clinically important antibodies in SSc. Making tests for anti-Th/To and -U3RNP antibodies widely available to clinicians should be helpful in the diagnosis and follow-up of SSc patients.

Frequency of disease-associated and other nuclear autoantibodies in patients of the German Network for Systemic Scleroderma: correlation with characteristic clinical features

Introduction

In the present study, we analysed in detail nuclear autoantibodies and their associations in systemic sclerosis (SSc) patients included in the German Network for Systemic Scleroderma Registry.

Methods

Sera of 863 patients were analysed according to a standardised protocol including immunofluorescence, immunoprecipitation, line immunoassay and immunodiffusion.

Results

Antinuclear antibodies (ANA) were detected in 94.2% of patients. In 81.6%, at least one of the autoantibodies highly associated with SSc or with overlap syndromes with scleroderma features was detected, that is, anti-centromere (35.9%) or anti-topoisomerase I (30.1%), followed in markedly lower frequency by antibodies to PM-Scl (4.9%), U1-ribonucleoprotein (U1-RNP) (4.8%), RNA polymerases (RNAPs) (3.8%), fibrillarin (1.4%), Ku (1.2%), aminoacyl-transfer RNA synthetases (0.5%), To (0.2%) and U11-RNP (0.1%). We found that the simultaneous presence of SSc-associated autoantibodies was rare (1.6%). Furthermore, additional autoantibodies were detected in 55.4% of the patients with SSc, of which anti-Ro/anti-La, anti-mitochondrial and anti-p25/p23 antibodies were most frequent. The coexistence of SSc-associated and other autoantibodies was common (43% of patients). SSc-associated autoantibodies disclosed characteristic associations with clinical features of patients, some of which were previously not acknowledged.

Conclusions

This study shows that five autoantigens (that is, centromere, topoisomerase I, PM-Scl, U1-RNP and RNAP) detected more than 95% of the known SSc-associated antibody responses in ANA-positive SSc patients and characterise around 79% of all SSc patients in a central European cohort. These data confirm and extend previous data underlining the central role of the determination of ANAs in defining the diagnosis, subset allocation and prognosis of SSc patients.

The scleroderma kidney: progress in risk factors, therapy, and prevention

Scleroderma renal crisis (SRC) is characterized by malignant hypertension, oliguric/anuric acute renal failure, and important mortality, with a 5-year survival rate of 65%. SRC occurs in 2% to 5% of patients with systemic sclerosis (SSc), particularly those with diffuse cutaneous SSc in the first years of disease evolution. Several retrospective studies have found high-dose corticosteroid therapy to be associated with increased risk of SRC, and anti-RNA-polymerase III antibodies have been detected in one third of patients with SRC. Treatment relies on the early control of blood pressure with increasing doses of angiotensin-converting enzyme inhibitors, eventually associated with calcium channel blockers together with dialysis if necessary. After 2 years on dialysis, eligible patients should be considered for renal transplantation. The strategy for prevention of SRC lacks consensus. However, corticosteroids and/or nephrotoxic drugs should be avoided in patients with diffuse cutaneous SSc.

Anti-RNA polymerase III antibody prevalence and associated clinical manifestations in a large series of French patients with systemic sclerosis: a cross-sectional study

OBJECTIVE

To determine the prevalence of anti-RNA polymerase III autoantibodies in French patients with systemic sclerosis (SSc) and to identify the associated clinical manifestations.

METHODS

Consecutive patients with SSc seen in 3 tertiary centers in Paris were included. Sera samples were collected together with the relevant clinical and immunological data. Anti-RNA polymerase III antibodies were detected by ELISA at a central laboratory. Data on other antibodies were abstracted from the medical records.

RESULTS

We included 319 patients: 84% women, 36% with a diffuse cutaneous subtype, 44% with pulmonary fibrosis, 5% with pulmonary hypertension, 4% with renal crisis, among whom 29 (9.4%) had anti-RNA polymerase III antibodies. These antibodies were more prevalent in patients with diffuse than with limited cutaneous disease (14.3% vs 6.0%; OR 2.6, 95% CI 1.2-5.48, p = 0.016). Renal crisis was more prevalent in patients with than in those without anti-RNA polymerase III antibodies (14% vs 3%; OR 5.0, 95% CI 1.4-17.3, p = 0.012). Renal crisis occurred in 2.2% of patients with anti-topoisomerase I and 3.9% of patients with anticentromere antibodies. Of the patients with anti-RNA polymerase III antibodies, 24 (83%) had no other systemic sclerosis-specific autoantibodies.

CONCLUSION

The prevalence of anti-RNA polymerase III antibodies in French patients appeared to be lower than in the United States and similar to that in continental Europe. These antibodies were consistently associated with diffuse cutaneous disease and were the most common immunological marker for renal crisis. Anti-RNA polymerase III determination can help to risk-stratify SSc patients at high risk for this severe manifestation.

Clinical usefulness of anti-RNA polymerase III antibody measurement by enzyme-linked immunosorbent assay

OBJECTIVE

To evaluate the clinical usefulness of measuring anti-RNA polymerase (RNAP) III antibody with a commercially available ELISA in Japanese patients with SSc.

METHODS

This multicentre study involved 354 patients with SSc, 245 with non-SSc CTDs and 102 healthy controls. ELISAs were used to detect anti-RNAP III antibody, anti-topo I antibody and ACA. The presence of anti-RNAP III antibody in selected serum samples was confirmed by immunoprecipitation (IP) assay.

RESULTS

By ELISA, anti-RNAP III antibody was detected in 38 (10.7%) patients with SSc, 3 (1.2%) with non-SSc CTD and no healthy controls. The clinical specificity for SSc was excellent (98.8%), although a small number of false positives occurred. The sensitivity of the anti-topo I and ACA ELISAs for SSc was 59.9%, which increased to 68.2% without a reduction in specificity when the anti-RNAP III measurement was added. Clinical features associated with positivity for the anti-RNAP III antibody include dcSSc, a high total skin score and a trend towards high prevalence of renal crisis, consistent with previous studies that used an IP assay. Furthermore, on clinical severity scales, SSc patients with anti-RNAP III antibody scored highest for skin and renal involvement among patients subgrouped by the presence of individual SSc-related antibodies.

CONCLUSIONS

The measurement of anti-RNAP III antibody by ELISA is useful in routine clinical practice, because it helps diagnose SSc and identify a disease subset with severe skin and renal involvement.

A longitudinal study of anti-RNA polymerase III antibody levels in systemic sclerosis

OBJECTIVES

Anti-RNA-polymerase antibodies (ARAs) are associated with the diffuse cutaneous subset of SSc (dcSSc) and particularly with scleroderma renal crisis (SRC). We analysed serial ARA levels and explored the relationship with clinical features and disease outcome.

METHODS

A commercially available ELISA method with a recombinant peptide of RNA polymerase III was used and ARA levels were measured in a well-characterized cohort of SSc cases.

RESULTS

ARA levels were measured in 64 SSc patients. Of them, 78% (n = 50) were females and 92% (n = 59) had dcSSc, 39% (n = 25) had SRC, 20% (n = 13) had pulmonary fibrosis (PF), 9% (n = 6) had pulmonary arterial hypertension and 3% (n = 2) had cardiac involvement. There was considerable inter- and intra-patient variability in ARA levels (11-210 U/ml). There was no correlation between absolute ARA levels (at baseline or throughout the disease course) and outcome. There was a moderate correlation between time to peak ARA level and development of significant PF (Pearson correlation = 0.669, P = 0.034), but no correlation between peak ARA levels and onset of SRC. ARA levels change correlated with change in skin score (correlation coefficient within subjects = 0.236, P = 0.011).

CONCLUSIONS

The pathogenic significance of ARA is unclear. Despite the very strong association of ARA with SRC, we could not show the clinically significant association between absolute levels of antibody and development of internal organ complications, which makes repeated measurements of ARA levels unnecessary. However, changes in ARA level over time occur and may reflect changes in skin score.

Serologic Profile and Mortality Rates of Scleroderma Renal Crisis in Italy

Objective.

To analyze clinical and serological characteristics of subjects with scleroderma renal crisis (SRC) in Italian patients with systemic sclerosis (SSc).

Methods.

A retrospective analysis of medical records from 9 Italian rheumatologic referral centers was carried out. All patients with SRC and an available serum sample at the time of crisis were included. Antinuclear antibodies (ANA) by indirect immunofluorescence, anti-topoisomerase (topo) I by enzyme-linked assay (ELISA), anti-RNA polymerases (RNAP) by ELISA for the subunit III, and immunoprecipitation (IP) were performed.

Results.

Forty-six cases (38 female; 40 diffuse cutaneous SSc) were identified. Mean age at SSc and SRC onset was 52.8 years ± 13.2 and 55.4 years ± 11.8, respectively. ANA were present in 44 patients (96%). Anti-topo I antibodies were detected in 30 (65%), anti-RNAP I–III in 7 (15%). No differences emerged between these 2 groups for their main clinical characteristics. The proportion of patients in the anti-RNAP I–III group developing SRC early (< 18 mo) in the course of SSc was significantly higher (p = 0.03). Cumulative survival rates were 64%, 53%, and 35% at 1, 2, and 10 years of followup, respectively. Survival rates of SSc patients significantly differed according to their autoantibody profile, being lower in the anti-topo I than in the anti-RNAP I–III group (p = 0.034).

Conclusion.

SRC is a rare manifestation of SSc in Italy but it is still associated with severe prognosis. Anti-topo I reactivity was more frequent than anti-RNAP I–III in our patients with SRC and was associated with delayed onset and high mortality rates.

Renal manifestations of systemic sclerosis--clinical features and outcome assessment

Renal manifestations occur frequently in scleroderma (SSc). Commonest is a reduction in renal function due to chronic disease but most clinically important is the scleroderma renal crisis (SRC). This life-threatening complication occurs in up to 15% of the cases of dcSSc. Mortality is reduced by use of angiotensin converting enzyme (ACE) inhibitors. Renal outcome can be assessed by quantifying renal function, measuring proteinuria, exploring the frequency of renal crisis episodes and through assessment of renal outcome following SRC-such as frequency and duration of dialysis, or recovery of renal function.

A case of renal crisis in a Korean scleroderma patient with anti-RNA polymerase I and III antibodies

Scleroderma (SSc) renal crisis has been reported to be associated with anti-RNA polymerase I and III (RNAP I/III) antibodies in Caucasians and the Japanese. However, no report is available for Korean SSc patients. Here, we describe the case of a 65-yr-old female SSc patient who developed renal crisis and whose serum contained anti-RNAP I/III antibodies. She was finally diagnosed as having diffuse cutaneous SSc based on skin thickening proximal to the elbows and knees. Sudden hypertension, oliguria, and pulmonary edema were features of her renal crisis. Despite the use of captopril and adequate blood pressure control, her renal function deteriorated. Subsequent renal biopsy findings showed severe fibrinoid necrosis with luminal obliteration in interlobar arteries and arterioles consistent with SSc renal crisis. Serum anti-RNAP I/III antibodies were detected by radioimmunoprecipitation. This is the first report of a renal crisis in a Korean SSc patient with RNAP I/III antibodies.

Endothelin axis polymorphisms in patients with scleroderma

OBJECTIVE

To evaluate the distribution of polymorphisms in the endothelin 1 (EDN1), endothelin receptor A (EDNRA) and endothelin receptor B (EDNRB) genes in systemic sclerosis (SSc; scleroderma) and SSc subsets.

METHODS

Two hundred five patients with SSc and 255 healthy controls were screened for polymorphisms in EDN1, EDNRA, and EDNRB, using sequence-specific primer-polymerase chain reaction. The polymorphisms studied were at the following positions: for EDN1, -1370 (T-1370G) of the promoter, +138 of exon 1 (+138 A/-), +85 of exon 3 (E106E), and +23 of exon 5 (K198N); for EDNRA, -231 of exon 1 (G-231A), and +69(H323H) and +105 (E335E) of exon 6; for EDNRB, +2841 of exon 2 (EDNRB-3), -2547 of exon 3 (EDNRB-2), and -2446 of exon 3 (EDNRB-1).

RESULTS

No significant differences between the SSc group as a whole and control subjects were observed for any of the investigated polymorphisms in EDN1, EDNRA, and EDNRB. However, compared with patients with limited cutaneous SSc, patients with diffuse skin involvement had an increased frequency of allele carriage of EDNRB-1A (76.8% versus 54.4%; P = 0.002), EDNRB-2A (79.7% versus 60.2%; P = 0.006), and EDNRB-3G (79.7% versus 56.6%; P = 0.001). Significantly increased carriage frequencies for EDNRA alleles H323H/C and E335E/A were observed in SSc patients with anti-RNA polymerase (anti-RNAP) antibodies, compared with both anti-RNAP-negative SSc patients (P < 0.05) and control subjects (P < 0.005).

CONCLUSION

The finding of associations between endothelin receptors A and B and distinct clinical and immunologic SSc subsets supports the role of endothelin and its receptors in the pathogenesis of SSc. However, these findings and their functional significance need to be confirmed and investigated in future studies.

From ANA to ENA: how to proceed?

Anti-nuclear antibodies (ANA), as detected by indirect immuno-fluorescence, are hallmarks of autoimmune connective tissue diseases. Identification of the specificity for extractable nuclear antigens (ENA) is warranted because this may further differentiate between the distinct types of autoimmune connective tissue diseases. In recent years several different ENA, as recognized by ANA, have been identified and the knowledge of the molecular structure has been expanded. Together with technical developments this has enabled the introduction of several new anti-ENA antibody detection systems. In this review we will discuss the main logistic aspects of anti-ENA antibody testing that have to be solved in order to come to a consensus in order to deal with new developments in this field. We conclude that: 1. a positive ANA test should, depending on the titre and pattern, be followed by an anti-ENA antibody assay, 2: to fully appreciate the value of the new anti-ENA antibody detection systems a large, multicenter clinical evaluation is required, and 3: proper interpretation of reported test results requires that the clinician is aware of the way anti-ENA antibodies are detected and reported.

Methods to detect antifibrillarin antibodies in patients with systemic sclerosis (SSc): a comparison

Autoantibodies against nucleolar antigens are common in systemic sclerosis (SSc). They include autoantibodies against fibrillarin (Fb), which are serological markers for SSc. Fb is associated with the evolutionally-conserved box C/D of small nucleolar RNAs (snoRNAs). We compared indirect immunofluorescence (IIF), Western blot (WB), and immunoprecipitation (IPP) of total small RNAs assays to determine which of these techniques is most specific for the detection of snoRNPs. We also examined the frequency and specificity of autoantibodies from SSc patients to snoRNAs, snRNAs, and scRNAs, and concluded that 1) IIF can not determine autoantibody specificity against Fb, 2) 36% of SSc sera were false-negative by WB, and 3) by IPP, anti-Fb autoantibodies from SSc patients can bind U3, U8, U13, U15, and U22 snoRNAs.

Mapping of the immunodominant T cell epitopes of the protein topoisomerase I

OBJECTIVES

To identify the immunodominant T cell epitopes of the topoisomerase I protein in patients with systemic sclerosis (SSc) and control subjects, using computational analysis software (TEPITOPE) and T cell proliferation assays.

METHODS

Six oligopeptides, predicted by TEPITOPE software as potential topoisomerase protein epitopes, were used to perform T cell proliferation assays in 21 patients with SSc and 15 healthy controls.

RESULTS

A positive response to at least one of the peptides was seen in 10/21 patients and 7/15 healthy controls. Among responders, the proliferative response was limited to a single peptide in 6/7 healthy controls, whereas 5/10 patients responded to more than one peptide. In responding patients a significant correlation was found between disease duration and number of peptides inducing a response (p = 0.007).

CONCLUSIONS

Several T cell epitopes of the topoisomerase I protein have been identified and evidence has been found to suggest epitope spreading in patients with SSc.

Antibodies in scleroderma: direct pathogenicity and phenotypic associations

Scleroderma is an autoimmune disease involving endothelial cell damage and fibroblast overproduction of extracellular matrix. Several autoantibodies present in the sera of patients with scleroderma, including anti-endothelial cell, antifibroblast, anti-matrix metalloproteinase, and antifibrillin-1 antibodies, may directly contribute to disease pathogenesis. Scleroderma also is characterized by the presence of antinuclear and antinucleolar antibodies, which correlate with particular phenotypes. These include antitopoisomerase-I, anticentromere, antihistone, anti-polymyositis/scleroderma, anti-Th/To, anti-U3-small nucleolar ribonucleoprotein particle, anti-U1-small nuclear ribonucleoprotein particle, anti-RNA polymerase, and anti-B23 antibodies. Other antibodies classically associated with other autoimmune diseases, such as antiphospholipid, antineutrophil cytoplasmic, and antimitochondrial antibodies, also have been described in patients with scleroderma. This review will summarize the various autoantibodies associated with scleroderma, their putative pathogenic roles, and their phenotypic correlations.

Autoantigenicity of nucleolar complexes

Autoantibodies targeting nucleolar autoantigens (ANoA) are most frequently found in sera from patients with systemic sclerosis (SSc, also designated scleroderma) or with SSc overlap syndromes. During the last decade an extensive number of nucleolar components have been identified and this allowed a more detailed analysis of the identity of nucleolar autoantigens. This review intends to give an overview of the molecular composition of the major (families of) autoantigenic nucleolar complexes, to provide some insight into their functions and to summarise the data concerning their autoantigenicity.

The assessment of the patient with systemic sclerosis

Systemic sclerosis presents a great deal of variability among different patients in the extent of skin and internal organ involvement, the pace of the disease and consequently, the prognosis. In addition, the single patient, during his/her disease course, can present with distinct manifestations. Each patient must, therefore, be carefully investigated. The assessment should be adapted to the setting, i.e. clinical practice, clinical investigation, therapeutic trials. The clinician cannot confine the diagnostic process to labelling the disease. He must define the subset, the extent of internal organ involvement, and the type of lesions underlying the clinical manifestations, i.e. fibrotic lesions, reflecting irreversible damage should be separated from active lesions (such as alveolitis) which can be reversed by drug treatment. The clinical investigator must assure that his/her patients are comparable to other series. ACR criteria have been shown to not assure such comparability. To this purpose, a core set of variables to be assessed in any clinical investigation study has been proposed. Finally, the clinical researcher should enrol patients with active disease and must rely for his/her conclusions on feasible and sensitive to change measures. An OMERACT committee has recently reviewed the literature selecting those ready for use in clinical trials.

The clinical relevance of autoantibodies in scleroderma

Scleroderma (systemic sclerosis) is associated with several autoantibodies, each of which is useful in the diagnosis of affected patients and in determining their prognosis. Anti-centromere antibodies (ACA) and anti-Scl-70 antibodies are very useful in distinguishing patients with systemic sclerosis (SSc) from healthy controls, from patients with other connective tissue disease, and from unaffected family members. Whereas ACA often predict a limited skin involvement and the absence of pulmonary involvement, the presence of anti-Scl-70 antibodies increases the risk for diffuse skin involvement and scleroderma lung disease. Anti-fibrillarin autoantibodies (which share significant serologic overlap with anti-U3-ribonucleoprotein antibodies) and anti-RNA-polymerase autoantibodies occur less frequently and are also predictive of diffuse skin involvement and systemic disease. Anti-Th/To and PM-Scl, in contrast, are associated with limited skin disease, but anti-Th/To might be a marker for the development of pulmonary hypertension. Other autoantibodies against extractable nuclear antigens have less specificity for SSc, including anti-Ro, which is a risk factor for sicca symptoms in patients with SSc, and anti-U1-ribonucleoprotein, which in high titer is seen in patients with SSc/systemic lupus erythematosus/polymyositis overlap syndromes. Limited reports of other autoantibodies (anti-Ku, antiphospholipid) have not established them as being clinically useful in following patients with SSc.

Cardiac involvement in systemic autoimmune diseases

The heart and the vascular system are frequent and characteristic targets of several systemic autoimmune diseases, in particular Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA) and Systemic Sclerosis (SSc). In this chapter we review the classic cardiac abnormalities and the more recent data about cardiovascular involvement as part of a major disease complication determining a substantial morbidity and mortality. In addition to the classic cardiac abnormalities involving the heart structures, acute and chronic ischemic heart disease and cerebrovascular accidents are threatening clinical manifestations of SLE and RA associated to an early accelerated atherosclerosis. Immune-mediated inflammation is now recognized as an important factor involved in the pathogenesis of atherosclerosis. Ongoing clinical studies are being devised to find specific risk factors associated with systemic autoimmune diseases and/or treatment regimens. Hopefully, prophylactic measures should be available within the next few years.

[Immunological diagnosis of scleroderma]

Systemic sclerosis is characterized by a fibrosis and a microvascular injury. These vascular lesions can affect internal organs causing severe visceral damages. The pathogenesis of this disease is complex but some immunological disorders with a production of antinuclear auto-antibodies can be useful to the clinicians, especially for an early diagnosis and to distinguish the scleroderma/myositis overlap syndromes. This review presents the target antigens and the methods of detection of the different antinuclear auto-antibodies. Sensitivity, specificity and clinical association between the antinuclear auto-antibodies and the different subclasses of scleroderma are also presented in detail.

Coexistence of antitopoisomerase I and anticentromere antibodies in patients with systemic sclerosis

BACKGROUND

Antibodies targeting DNA topoisomerase I (ATA) or centromere proteins (ACA) are associated with clinical subsets of patients with systemic sclerosis (SSc). The occurrence of those autoantibodies is considered to be mutually exclusive.

OBJECTIVE

To describe the clinical and immunogenetic data of three patients who are co-expressing both antibodies, and then review previous publications.

METHODS

Both antibodies were detected by different methods, including indirect immunofluorescence technique, enzyme linked immunosorbent assay, immunodiffusion, and immunoblot. Patients were HLA typed by serological and molecular genetic methods. Data were extracted from published reports for comparison. The search for published studies was through Medline and other database research programmes.

RESULTS

During routine laboratory diagnostics over several years three patients with scleroderma and coincidence of ATA and ACA were identified: patient 1 with diffuse SSc, Raynaud's phenomenon, puffy fingers and fingertip necrosis, contractures, and calcinosis; patient 2 with diffuse SSc, Raynaud's phenomenon, oedema of the hands, and interstitial calcinosis of hands, knees, and shoulders, and pulmonary fibrosis; patient 3 with scleroderma of hands, forearms, and face, Raynaud's phenomenon, puffy fingers, finger contractures, fingertip necrosis, and calcinosis. All three patients studied were carriers of HLA alleles known to be associated with these autoantibodies. In serial measurements the concentrations of the two antibodies showed independent or even reverse fluctuations. Screening of 100 patients with ACA for ATA and vice versa disclosed no further patients with coincidence of these antibodies. Twenty eight cases of ACA/ATA coexistence in 5423 patients (0.52%) with SSc or SSc associated symptoms were found in an analysis of published studies.

CONCLUSION

The expression of ATA and ACA is not totally mutually exclusive, but coincidence is rare (<1% of patients with SSc). Patients with both autoantibodies often have diffuse scleroderma and show immunogenetic features of both antibody defined subsets of SSc.

Systemic sclerosis (scleroderma): specific autoantigen genes are selectively overexpressed in scleroderma fibroblasts

The pathogenesis of systemic sclerosis (SSc) involves complex interactions between activated fibroblasts eventually leading to fibrosis, and impaired immune tolerance characterized by a variety of circulating SSc-specific autoantibodies. The expression of autoantigens in fibroblasts, a key target tissue in SSc, may play an important role in this process. To obtain a global view of this process, we examined gene expression profiles of SSc dermal fibroblasts using cDNA microarrays. The results show that dermal fibroblasts from SSc patients obtained from either affected or unaffected skin displayed a characteristic pattern of increased SSc autoantigen gene expression compared with that from normal controls. In particular, fibrillarin (p = 0.028), centromeric protein B (p = 0.01), centromeric autoantigen P27 (p = 0.042), and RNA polymerase II (220 kDa; p = 0.02) were significantly overexpressed in SSc fibroblasts. Quantitative RT-PCR confirmed overexpression of these autoantigens and also revealed increased levels of DNA topoisomerase I transcripts in SSc fibroblasts compared with normal control fibroblasts (p = 0.0318). The polymyositis/scleroderma autoantigen gene was overexpressed in some SSc patients (p = 0.09). To examine the specificity of these overexpressed autoantigen genes for SSc and its tissue specificity for fibroblasts, cDNA microarrays of dermal fibroblasts from patients with eosinophilic fasciitis and scleromyxedema were studied as well as PBMC and muscle biopsies from SSc patients. None of these tissues showed significant alterations in gene expression of SSc-specific autoantigens. Therefore, SSc-associated autoantigen genes are selectively overexpressed in SSc dermal fibroblasts, a major tissue involved in disease pathogenesis.