Agreement between local and central anti-synthetase antibodies detection: results from the Classification Criteria of Anti-Synthetase Syndrome project biobank

OBJECTIVES

The CLASS (Classification Criteria of Anti-Synthetase Syndrome) project is a large international multicentre study that aims to create the first data-driven anti-synthetase syndrome (ASSD) classification criteria. Identifying anti-aminoacyl tRNA synthetase antibodies (anti-ARS) is crucial for diagnosis, and several commercial immunoassays are now available for this purpose. However, using these assays risks yielding false-positive or false-negative results, potentially leading to misdiagnosis. The established reference standard for detecting anti-ARS is immunoprecipitation (IP), typically employed in research rather than routine autoantibody testing. We gathered samples from participating centers and results from local anti-ARS testing. As an "ad-interim" study within the CLASS project, we aimed to assess how local immunoassays perform in real-world settings compared to our central definition of anti-ARS positivity.

METHODS

We collected 787 serum samples from participating centres for the CLASS project and their local anti-ARS test results. These samples underwent initial central testing using RNA-IP. Following this, the specificity of ARS was reconfirmed centrally through ELISA, line-blot assay (LIA), and, in cases of conflicting results, protein-IP. The sensitivity, specificity, positive likelihood ratio and positive and negative predictive values were evaluated. We also calculated the inter-rater agreement between central and local results using a weighted κ co-efficient.

RESULTS

Our analysis demonstrates that local, real-world detection of anti-Jo1 is reliable with high sensitivity and specificity with a very good level of agreement with our central definition of anti-Jo1 antibody positivity. However, the agreement between local immunoassay and central determination of anti-non-Jo1 antibodies varied, especially among results obtained using local LIA, ELISA and "other" methods.

CONCLUSIONS

Our study evaluates the performance of real-world identification of anti-synthetase antibodies in a large cohort of multi-national patients with ASSD and controls. Our analysis reinforces the reliability of real-world anti-Jo1 detection methods. In contrast, challenges persist for anti-non-Jo1 identification, particularly anti-PL7 and rarer antibodies such as anti-OJ/KS. Clinicians should exercise caution when interpreting anti-synthetase antibodies, especially when commercial immunoassays test positive for non-anti-Jo1 antibodies.

A Negative Antinuclear Antibody Does Not Indicate Autoantibody Negativity in Myositis: Role of Anticytoplasmic Antibody as a Screening Test for Antisynthetase Syndrome

Objective.

To evaluate the utility of anticytoplasmic autoantibody (anti-CytAb) in antisynthetase antibody–positive (anti-SynAb+) patients.

Methods.

Anti-SynAb+ patients were evaluated for antinuclear antibody (ANA) and anti-CytAb [cytoplasmic staining on indirect immunofluorescence (IIF)] positivity. Anti-SynAb+ patients included those possessing anti-Jo1 and other antisynthetase autoantibodies. Control groups included scleroderma, systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis, and healthy subjects. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy of anti-CytAb, and ANA were assessed. Anti-CytAb and ANA testing was done by IIF on human epithelial cell line 2, both reported on each serum sample without knowledge of the clinical diagnosis or final anti-SynAb results.

Results.

Anti-SynAb+ patients (n = 202; Jo1, n = 122; non-Jo1, n = 80) between 1985–2013 with available serum samples were assessed. Anti-CytAb showed high sensitivity (72%), specificity (89%), NPV (95%), and accuracy (86%), but only modest PPV (54%) for anti-SynAb positivity. In contrast, ANA showed only modest sensitivity (50%) and poor specificity (6%), PPV (9%), NPV (41%), and accuracy (12%). Positive anti-CytAb was significantly greater in the anti-SynAb+ patients than ANA positivity (72% vs 50%, p < 0.001), and 81/99 (82%) ANA-negative patients in the anti-SynAb+ cohort had positive anti-CytAb. In contrast, the control groups showed high rates for ANA positivity (93.5%), but very low rates for anti-CytAb positivity (11.5%). Combining anti-CytAb or Jo1 positivity showed high sensitivity (92%) and specificity (89%) for identification of anti-SynAb+ patients.

Conclusion.

Assessing patients for anti-CytAb serves as an excellent screen for anti-SynAb+ patients using simple IIF. Cytoplasmic staining should be assessed and reported for patients suspected of having antisynthetase syndrome and a negative ANA should not be used to exclude this diagnosis.

Anti-signal recognition particle autoantibody ELISA validation and clinical associations

OBJECTIVE

The aim of this study was to develop and validate a quantitative anti-signal recognition particle (SRP) autoantibody serum ELISA in patients with myositis and longitudinal association with myositis disease activity.

METHODS

We developed a serum ELISA using recombinant purified full-length human SRP coated on ELISA plates and a secondary antibody that bound human IgG to detect anti-SRP binding. Protein immunoprecipitation was used as the gold standard for the presence of anti-SRP. Serum samples from three groups were analysed: SRP(+) myositis subjects by immunoprecipitation, SRP(-) myositis subjects by immunoprecipitation and non-myositis controls. The ELISA's sensitivity, specificity, positive predictive value and negative predictive value were evaluated. Percentage agreement and test-retest reliability were assessed. Serial samples from seven SRP immunoprecipitation-positive subjects were also tested, along with serum muscle enzymes and manual muscle testing.

RESULTS

Using immunoprecipitation, we identified 26 SRP(+) myositis patients and 77 SRP(-) controls (including 38 patients with necrotizing myopathy). Non-myositis control patients included SLE (n = 4) and SSc (n = 7) patients. Anti-SRP positivity by ELISA showed strong agreement (97.1%) with immunoprecipitation (κ = 0.94). The sensitivity, specificity, positive predictive value, and negative predictive value of the anti-SRP ELISA were 88, 100, 100 and 96, respectively. The area under the curve was 0.94, and test-retest reliability was strong (r = 0.91, P < 0.001). Serial samples showed that anti-SRP levels paralleled changes in muscle enzymes and manual muscle testing.

CONCLUSION

We developed a quantitative ELISA for detecting serum anti-SRP autoantibodies and validated the assay in myositis. Longitudinal assessment of SRP levels by ELISA may be a useful biomarker for disease activity.

Anti-transcription intermediary factor 1-gamma autoantibody ELISA development and validation

OBJECTIVES

A quantitative anti-transcription intermediary factor 1-gamma (anti-TIF1-γ) ELISA may improve the detection of cancer-associated myositis (CAM). The aims of this study were the development and validation of a quantitative anti-TIF1-γ autoantibody ELISA in patients with myositis.

METHODS

We developed an ELISA using recombinant purified full-length human TIF1-γ. Patient serum was incubated with TIF1-γ-coated ELISA plates, and secondary antibody that bound human IgG was used to detect anti-TIF1-γ binding. Protein immunoprecipitation (IP) was used as the gold standard for the presence of anti-TIF1-γ. Serum samples from myositis patients with positive and negative anti-TIF1-γ by IP, from non-myositis autoimmune patients (SSc, SLE and RA) and from healthy controls were analysed. The ELISA's sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were evaluated. Agreement between the ELISA and IP results was determined using chi-squared and kappa tests. Test-retest reliability of the ELISA was assessed.

RESULTS

We identified 55 myositis patients with and 111 controls without anti-TIF1-γ by IP. Anti-TIF1-γ positivity by ELISA showed strong agreement (93.9%) with IP results (κ = 0.87). The sensitivity, specificity, PPV, NPV and overall accuracy of the anti-TIF1-γ ELISA were 91%, 96%, 93%, 95% and 94%, respectively. The area under the curve (AUC) of a receiver operating characteristic (ROC) curve was 0.938. Test-retest reliability was strong (Pearson r = 0.913, P < 0.001).

CONCLUSION

We developed a quantitative ELISA for detecting serum anti-TIF1-γ autoantibodies and validated the assay in myositis and other connective tissue disease patients. The availability of a validated, quantitative ELISA should improve the detection of anti-TIF1-γ autoantibodies and may improve the detection of CAM.

Rituximab in the treatment of refractory adult and juvenile dermatomyositis and adult polymyositis: a randomized, placebo-phase trial

OBJECTIVE

To assess the safety and efficacy of rituximab in a randomized, double-blind, placebo-phase trial in adult and pediatric myositis patients.

METHODS

Adults with refractory polymyositis (PM) and adults and children with refractory dermatomyositis (DM) were enrolled. Entry criteria included muscle weakness and ≥2 additional abnormal values on core set measures (CSMs) for adults. Juvenile DM patients required ≥3 abnormal CSMs, with or without muscle weakness. Patients were randomized to receive either rituximab early or rituximab late, and glucocorticoid or immunosuppressive therapy was allowed at study entry. The primary end point compared the time to achieve the International Myositis Assessment and Clinical Studies Group preliminary definition of improvement (DOI) between the 2 groups. The secondary end points were the time to achieve ≥20% improvement in muscle strength and the proportions of patients in the early and late rituximab groups achieving the DOI at week 8.

RESULTS

Among 200 randomized patients (76 with PM, 76 with DM, and 48 with juvenile DM), 195 showed no difference in the time to achieving the DOI between the rituximab late (n = 102) and rituximab early (n = 93) groups (P = 0.74 by log rank test), with a median time to achieving a DOI of 20.2 weeks and 20.0 weeks, respectively. The secondary end points also did not significantly differ between the 2 treatment groups. However, 161 (83%) of the randomized patients met the DOI, and individual CSMs improved in both groups throughout the 44-week trial.

CONCLUSION

Although there were no significant differences in the 2 treatment arms for the primary and secondary end points, 83% of adult and juvenile myositis patients with refractory disease met the DOI. The role of B cell-depleting therapies in myositis warrants further study, with consideration for a different trial design.

Patients with non-Jo-1 anti-tRNA-synthetase autoantibodies have worse survival than Jo-1 positive patients

OBJECTIVE

To compare the cumulative survival and event free survival in patients with Jo-1 versus non-Jo-1 anti-tRNA synthetase autoantibodies (anti-synAb).

METHODS

Anti-synAb positive patients initially evaluated from 1985 to 2009 were included regardless of the connective tissue disease (CTD) diagnosis. Clinical data were extracted from a prospectively collected database and chart review. Survival between Jo-1 and non-Jo-1 was compared by log rank and Cox proportional hazards methods.

RESULTS

202 patients possessed anti-synAb: 122 Jo-1 and 80 non-Jo-1 (35 PL-12; 25 PL-7; 9 EJ; 6 KS; 5 OJ). The diagnoses at first visit for Jo-1 and non-Jo-1 patients were myositis in 83% and 40.0%, overlap or undifferentiated CTD in 17% and 47.5%, and systemic sclerosis in 0% and 12.5%, respectively (p<0.001). The median delay in diagnosis was 0.4 years in Jo-1 patients versus 1.0 year in non-Jo-1 patients (p<0.001). The most common causes of death in the overall cohort were pulmonary fibrosis in 49% and pulmonary hypertension in 11%. The 5- and 10-year unadjusted cumulative survival was 90% and 70% for Jo-1 patients, and 75% and 47% for non-Jo-1 patients (p<0.005). The hazard ratio (HR) of non-Jo-1 patients compared with Jo-1 patients was 1.9 (p=0.01) for cumulative and 1.9 (p=0.008) for event free survival from diagnosis. Age at first diagnosis and diagnosis delay but not gender, ethnicity and CTD diagnosis influenced survival.

CONCLUSIONS

Non-Jo-1 anti-synAb positive patients have decreased survival compared with Jo-1 patients. The difference in survival may be partly attributable to a delay in diagnosis in the non-Jo-1 patients.

A clinical and serologic comparison of African American and Caucasian patients with systemic sclerosis

OBJECTIVE

Epidemiology studies suggest that systemic sclerosis (SSc) is more common, occurs at a younger age, and is more severe in African Americans than Caucasians. However, the scleroderma autoantibody profile is very different between these 2 ethnic groups. This study was undertaken to examine the demographic and disease features, frequency and severity of internal organ system involvement, and survival in African American patients compared to Caucasian patients with SSc, giving particular attention to their serum autoantibody profiles.

METHODS

Demographic features, clinical characteristics, autoantibody profile, organ involvement, and survival were studied in consecutive African American and Caucasian patients with SSc whose visits were recorded between 1972 and 2007 as part of the Pittsburgh Scleroderma Database. The Medsger Severity Score for SSc was used to determine the severity of disease.

RESULTS

African American patients were more likely to have anti-topoisomerase I (anti-topo I), anti-U1 RNP, and anti-U3 RNP autoantibodies. In comparing African American and Caucasian patients with these antibodies, pulmonary fibrosis was found to be more frequent and more severe, and the rate of survival was decreased, in African American patients with anti-topo I antibodies compared to Caucasian patients with anti-topo I. Pulmonary fibrosis was also more severe in the anti-U1 RNP-positive patients, but this was not associated with a difference in survival between African Americans and Caucasians. Anti-U3 RNP was associated with more severe gastrointestinal involvement in African Americans compared to Caucasians.

CONCLUSION

African Americans with SSc have more severe disease complications compared to Caucasians with SSc, and this is associated with both the type of autoantibody present and the severity of interstitial lung disease. Thus, it is hoped that early aggressive intervention in African Americans with interstitial lung disease will improve outcomes.

Anti-PM-Scl antibody in patients with systemic sclerosis

OBJECTIVES

To compare systemic sclerosis (SSc) patients with and without anti-PM-Scl antibody.

METHODS

We reviewed the medical records of 76 anti-PM-Scl antibody positive SSc patients and 2349 anti-PMScl negative SSc patients first evaluated during 1980-2004. Patients were included if they had a clinical diagnosis of SSc either alone or in overlap with another connective tissue disease. Anti-PM-Scl antibody was screened for by indirect immunofluorescence and tested by Ouchterlony double immunodiffusion.

RESULTS

Anti-PM-Scl antibody positive patients had a significantly higher frequency of a positive ANA with nucleolar staining (87% vs. 32%, p<0.0001) and were younger at both symptom onset (p=0.004) and first physician diagnosis of SSc (p<0.001). They were classified more often as having overlap with another connective tissue disease, particularly polymyositis-dermatomyositis, and more frequently had limited cutaneous involvement (72% vs. 52%, p=0.001). Maximal skin thickening was less in anti-PM-Scl antibody patients (mean modified Rodnan total skin score 6.0±6.3 vs. 15.9±14.2, p<0.001). Anti-PM-Scl antibody positive patients less frequently had peripheral vascular (91% vs. 98%, p=0.0002) and gastrointestinal (52% vs. 79%, p=0.0001) disease. Lung involvement overall had a similar distribution between both groups. However, radiographic evidence of pulmonary fibrosis was more frequent in anti-PM-Scl antibody positive patients (50% vs. 37%, p=0.05) and pulmonary arterial hypertension was less often detected (5% vs. 15%, p<0.04). Skeletal muscle involvement (51% vs. 14%, p<0.0001) and subcutaneous calcinosis (p<0.003) were both significantly more often observed in anti-PM-Scl antibody positive patients. Joint, heart, and kidney involvement were similar in both groups. Overall survival was significantly better for anti-PM-Scl antibody positive patients (10 year cumulative survival rate 91% vs. 65%, p=0.0002). After adjustment for age, sex and limited vs. diffuse cutaneous involvement, patients with anti-PM-Scl antibody were significantly less likely to die (HR=0.32, 95% CI, [0.14, 0.72] p=0.006).

CONCLUSIONS

SSc patients with anti-PM-Scl antibody are younger and significantly more often have limited cutaneous involvement, skeletal muscle disease, pulmonary fibrosis and calcinosis compared to anti-PM-Scl antibody negative SSc patients. Ten-year cumulative survival is significantly better in anti-PM-Scl antibody positive SSc patients.

Genetic association study of NF-κB genes in UK Caucasian adult and juvenile onset idiopathic inflammatory myopathy

Objective. Treatment-resistant muscle wasting is an increasingly recognized problem in idiopathic inflammatory myopathy (IIM). TNF-α is thought to induce muscle catabolism via activation of nuclear factor-kappa B (NF-κB). Several genes share homology with the NF-κB family of proteins. This study investigated the role of NF-κB-related genes in disease susceptibility in UK Caucasian IIM.

Methods. Data from 362 IIM cases [274 adults, 49 (±14.0) years, 72% female; 88 juveniles, 6 (±3.6) years, 73% female) were compared with 307 randomly selected Caucasian controls. DNA was genotyped for 63 single nucleotide polymorphisms (SNPs) from NF-κB-related genes. Data were stratified by IIM subgroup/serotype.

Results. A significant allele association was observed in the overall IIM group vs controls for the IKBL-62T allele (rs2071592, odds ratio 1.5, 95% CI 1.21, 1.89, corrected P = 0.0086), which strengthened after stratification by anti-Jo-1 or -PM-Scl antibodies. Genotype analysis revealed an increase for the AT genotype in cases under a dominant model. No other SNP was associated in the overall IIM group. Strong pairwise linkage disequilibrium was noted between IKBL-62T, TNF-308A and HLA-B*08 (D′ = 1). Using multivariate regression, the IKBL-62T IIM association was lost after adjustment for TNF-308A or HLA-B*08.

Conclusion. An association was noted between IKBL-62T and IIM, with increased risk noted in anti-Jo-1- and -PM-Scl antibody-positive patients. However, the IKBL-62T association is dependent on TNF-308A and HLA-B*08, due to strong shared linkage disequilibrium between these alleles. After adjustment of the 8.1 HLA haplotype, NF-κB genes therefore do not independently confer susceptibility in IIM.

Skin thickness progression rate: a predictor of mortality and early internal organ involvement in diffuse scleroderma

OBJECTIVE

To examine the association of skin thickness progression rate (STPR) with mortality, and as a predictor of future internal organ involvement in an inception cohort of diffuse cutaneous systemic sclerosis (SSc) patients.

METHODS

Diffuse cutaneous SSc patients older than 16 years of age evaluated at the University of Pittsburgh within 2 years of the first evidence of skin thickening between 1980 and 2005 were eligible. The authors calculated the STPR on these patients, and examined the relationship of this variable to the development of early internal organ involvement and short-term mortality using logistic regression.

RESULTS

826 patients were included in the analysis. Patients with a rapid STPR experienced significantly reduced short-term survival at 1 and 2 years from the time of first Pittsburgh evaluation (p=0.002). Patients with a rapid STPR were more likely to develop renal crisis within 1-2 years of follow-up. Rapid STPR was found to be an independent predictor of both mortality (OR 1.72; 95% CI 1.13 to 2.62; p=0.01) and 'renal crisis' (OR 2.05, 95% CI 1.10 to 3.85; p=0.02) within 2 years from first evaluation.

CONCLUSION

The STPR is an easy measure to perform at the time of initial evaluation for identifying those diffuse cutaneous SSc patients who are at increased risk of mortality and the development of renal crisis during the following 2 years.

Anti-U11/U12 RNP antibodies in systemic sclerosis: a new serologic marker associated with pulmonary fibrosis

OBJECTIVE

To characterize a new serum autoantibody in patients with systemic sclerosis (SSc) directed against U11/U12 RNP and to identify the clinical features associated with this autoantibody.

METHODS

We identified autoantibodies directed against the U11/U12 RNP complex in sera of patients with SSc and confirmed antibody specificity by immunoprecipitation, reverse transcriptase-polymerase chain reaction, and Southern blotting. We determined the prevalence of these antibodies in SSc and their specificity for SSc. We compared anti-U11/U12 RNP autoantibody-positive and negative SSc patients on demographic, disease classification, clinical variables, and survival.

RESULTS

We identified 33 patients with anti-U11/U12 RNP antibodies. In 2 consecutive series of SSc patients first seen at 10-year intervals (1994-1995 and 2004-2005), the prevalence of anti-U11/U12 RNP antibody-positive patients was 15 of 462 (3.2%). Seventeen (52%) of these 33 patients had limited cutaneous involvement. All patients had Raynaud's phenomenon and 82% had gastrointestinal (GI) involvement. None had "intrinsic" pulmonary arterial hypertension. The most significant clinical difference between anti-U11/U12 antibody-positive and negative cohorts was the prevalence of lung fibrosis, which occurred in 79% of the anti-U11/U12 RNP antibody-positive patients versus 37% of the anti-U11/U12 RNP antibody-negative patients (P < 0.0001). GI involvement was also significantly increased in the anti-U11/U12 RNP antibody-positive group. Patients with anti-U11/U12 RNP antibodies and pulmonary fibrosis had a 2.25-fold greater risk of death than anti-U11/U12 RNP negative patients with pulmonary fibrosis.

CONCLUSION

Anti-U11/U12 RNP antibodies are present in the sera of approximately 3% of patients with SSc and are a marker for lung fibrosis, which is often severe.

Characterization and peripheral blood biomarker assessment of anti-Jo-1 antibody-positive interstitial lung disease

OBJECTIVE

Using a combination of clinical, radiographic, functional, and serum protein biomarker assessments, this study was aimed at defining the prevalence and clinical characteristics of interstitial lung disease (ILD) in a large cohort of patients with anti-Jo-1 antibodies.

METHODS

A review of clinical records, pulmonary function test results, and findings on imaging studies determined the existence of ILD in anti-Jo-1 antibody-positive individuals whose data were accumulated in the University of Pittsburgh Myositis Database from 1982 to 2007. Multiplex enzyme-linked immunosorbent assays (ELISAs) for serum inflammation markers, cytokines, chemokines, and matrix metalloproteinases in different patient subgroups were performed to assess the serum proteins associated with anti-Jo-1 antibody-positive ILD.

RESULTS

Among the 90 anti-Jo-1 antibody-positive individuals with sufficient clinical, radiographic, and/or pulmonary function data, 77 (86%) met the criteria for ILD. While computed tomography scans revealed a variety of patterns suggestive of underlying usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia, a review of the histopathologic abnormalities in a subset of patients undergoing open lung biopsy or transplantation or whose lung tissue was obtained at autopsy (n = 22) demonstrated a preponderance of UIP and diffuse alveolar damage. Analysis by multiplex ELISA yielded statistically significant associations between anti-Jo-1 antibody-positive ILD and elevated serum levels of C-reactive protein (CRP), CXCL9, and CXCL10, which distinguished this disease entity from idiopathic pulmonary fibrosis and anti-signal recognition particle antibody-positive myositis. Recursive partitioning further demonstrated that combinations of these and other serum protein biomarkers can distinguish these disease subgroups at high levels of sensitivity and specificity.

CONCLUSION

In this large cohort of anti-Jo-1 antibody-positive individuals, the incidence of ILD approached 90%. Multiplex ELISA demonstrated disease-specific associations between anti-Jo-1 antibody-positive ILD and serum levels of CRP as well as the interferon-gamma-inducible chemokines CXCL9 and CXCL10, highlighting the potential of this approach to define biologically active molecules contributing to the pathogenesis of myositis-associated ILD.

HLA-DPB1 associations differ between DRB1*03 positive anti-Jo-1 and anti-PM-Scl antibody positive idiopathic inflammatory myopathy

OBJECTIVE

The HLA 8.1 ancestral haplotype (HLA-B*08/DRB1*03/DQA1*05/DQB1*02) is associated with adult/juvenile idiopathic inflammatory myopathy (IIM), but confers a greater strength of association in patients possessing anti-Jo-1 or anti-PM-Scl antibodies. The HLA-DPB1 gene is centromeric to other HLA class II loci and separated by a recombination hotspot. We investigated whether HLA-DPB1 associations differ between anti-Jo-1 and anti-PM-Scl antibody-positive IIM cases.

METHODS

Two hundred and thirty-three adult IIM patients (73% females, 49.4 +/- 13.6 years) with PM (n = 89), DM (n = 88) and myositis associated with another CTD (n = 55) and 85 juvenile DM patients (75% females, 6.2 +/- 3.6 years) were compared with 678 UK Caucasian controls. Patients/controls were genotyped for HLA-DPB1 and DRB1 alleles. Myositis-specific and associated antibodies were identified in cases using immunoprecipitation.

RESULTS

HLA-DPB1*0101 was associated with IIM overall [22 vs 13% controls, corrected probability (P(corr)) = 2 x 10(-03); odds ratio (OR) 2.0; 95% CI 1.4, 2.9], PM (P(corr) = 7 x 10(-03); OR 2.5; 95% CI 1.5, 4.4) and anti-Jo-1 (P(corr) = 3 x 10(-5); OR 4.1; 95% CI 2.1, 7.8). No significant DPB1*0101 difference was present between anti-PM-Scl cases and controls. The HLA-DPB1*0101 association in IIM overall cases was dependent on the presence of DRB1*03. A number of HLA-DRB1*03/DPB1 haplotypes were identified, but only DRB1*03/DPB1*0101 was associated with anti-Jo-1 antibody-positive cases.

CONCLUSIONS

The HLA-DRB1*03/DPB1*0101 haplotype is a risk factor for anti-Jo-1 antibody-positive IIM. Thus, although DRB1*03 is strongly associated with possession of either anti-Jo-1 or anti-PM-Scl, differing antibody associations are observed at the HLA-DPB1 locus.

Anti-U3 RNP autoantibodies in systemic sclerosis

OBJECTIVE

To describe the classification, demographic and clinical features, and survival in anti-U3 RNP autoantibody-positive patients with systemic sclerosis (SSc).

METHODS

Medical records of 108 anti-U3 RNP-positive and 2,471 anti-U3 RNP-negative SSc patients first evaluated during 1985-2003 were reviewed. Anti-U3 RNP antibody was detected by protein and RNA immunoprecipitation. Disease classification, demographic and clinical features, organ system involvement, and survival were compared between the 2 patient groups, by Student's t-test, chi-square analysis, and Mantel-Haenszel test.

RESULTS

The anti-U3 RNP-positive group had a higher proportion of African American patients (27% versus 5%; P < 0.001) and male patients (29% versus 19%; P = 0.021), and was younger at the time of first physician diagnosis (mean age 42.8 years versus 47.4 years; P = 0.001). The 2 groups had similar proportions of patients with diffuse cutaneous involvement (47% and 45% in those with and those without anti-U3 RNP, respectively). However, among patients with diffuse cutaneous involvement, the mean maximum modified Rodnan skin score was significantly lower in the anti-U3 RNP group (22.3 versus 27.9; P < 0.001). Skeletal muscle involvement was more frequent in anti-U3 RNP-positive patients (25% versus 14%; P = 0.002), as was "intrinsic" pulmonary arterial hypertension (PAH) (31% versus 13%; P < 0.001). The frequency of gastrointestinal involvement, cardiac involvement, pulmonary fibrosis, and "renal crisis" did not differ significantly between the 2 groups. Survival was worse in the anti-U3 RNP-positive group (hazard ratio 1.38 [95% confidence interval 1.05-1.82]). PAH was the most common known cause of death in patients with anti-U3 RNP (30%, versus 10% in the anti-U3 RNP-negative group; P < 0.001).

CONCLUSION

The present findings demonstrate that the frequencies of African American race and male sex are greater among SSc patients with anti-U3 RNP antibody than those without, and the former group is younger at SSc diagnosis. Anti-U3 RNP-positive patients have more frequent skeletal muscle involvement and PAH, the latter being the most common cause of death.

The protein tyrosine phosphatase N22 gene is associated with juvenile and adult idiopathic inflammatory myopathy independent of the HLA 8.1 haplotype in British Caucasian patients

OBJECTIVE

To examine single-nucleotide polymorphisms (SNPs) of the protein tyrosine phosphatase N22 gene (PTPN22) and to study the relationship between PTPN22 and the HLA region in patients with idiopathic inflammatory myopathies (IIMs).

METHODS

PTPN22 SNPs were assessed in a large, cross-sectional, case-control study from the UK involving patients with adult or juvenile IIM, comprising patients with polymyositis (PM) (n=114), dermatomyositis (DM) (n=102), myositis associated with another connective tissue disease (myositis-CTD overlap syndrome) (n=64), or juvenile DM (n=101), in comparison with 748 control subjects. Seventeen PTPN22 SNPs were genotyped using the Sequenom MassArray iPLEX platform. Serotyping for myositis-specific/myositis-associated autoantibodies (MSAs/MAAs) was performed by radioimmunoprecipitation.

RESULTS

A significant association was noted between the R620W variant (rs2476601) and IIM (corrected P [Pcorr]=0.0009 versus controls), and specifically with the clinical subgroup of PM (Pcorr=0.003 versus controls). A weaker association was noted with juvenile DM (Pcorr=0.009 versus controls). No significant associations were noted after stratification by serologic subgroups. The association with the R620W variant was independent of alleles forming the HLA 8.1 haplotype. No other PTPN22 SNPs were associated with IIM. The PTPN22 haplotype containing the R620W T allele was the only haplotype significantly associated with IIM.

CONCLUSION

The R620W variant is a significant risk factor for IIM, independent of the HLA 8.1 haplotype. Unlike that in the HLA region, risk is not increased in individuals possessing MSAs/MAAs. These results are further evidence that the PTPN22 gene confers autoimmune susceptibility.

Species-specific immune responses generated by histidyl-tRNA synthetase immunization are associated with muscle and lung inflammation

Evidence implicating histidyl-tRNA synthetase (Jo-1) in the pathogenesis of the anti-synthetase syndrome includes established genetic associations linking the reproducible phenotype of muscle inflammation and interstitial lung disease with autoantibodies recognizing Jo-1. To better address the role of Jo-1-directed B and T cell responses in the context of different genetic backgrounds, we employed Jo-1 protein immunization of C57BL/6 and NOD congenic mice. Detailed analysis of early antibody responses following inoculation with human or murine Jo-1 demonstrates remarkable species-specifity, with limited cross recognition of Jo-1 from the opposite species. Complementing these results, immunization with purified peptides derived from murine Jo-1 generates B and T cells targeting species-specific epitopes contained within the amino terminal 120 amino acids of murine Jo-1. The eventual spreading of B cell epitopes that uniformly occurs 8 weeks post immunization with murine Jo-1 provides additional evidence of an immune response mediated by autoreactive, Jo-1-specific T cells. Corresponding to this self-reactivity, mice immunized with murine Jo-1 develop a striking combination of muscle and lung inflammation that replicates features of the human anti-synthetase syndrome.

Pulmonary arterial hypertension and severe pulmonary fibrosis in systemic sclerosis patients with a nucleolar antibody

OBJECTIVE

Pulmonary arterial hypertension (PAH) and severe pulmonary fibrosis (SPF) are the most common causes of death in scleroderma. Our study focuses on lung disease in patients with a nucleolar antibody in comparison to other scleroderma-specific autoantibodies.

METHODS

Patients initially seen between 1972 and 1995 (and followed through 2004) with [systolic pulmonary artery pressure (sPAH) (PASP > 50 mm Hg] or SPF [forced vital capacity (FVC%) < 55% predicted) were grouped by the presence of anticentromere antibody (ACA), an isolated antinucleolar antibody (ANoA), or an antitopoisomerase antibody-I (TOPO).

RESULTS

Twenty percent of ACA, 23% of TOPO, and 32% of ANoA patients had severe lung disease (p < 0.005). In ANoA patients with PAH without severe fibrosis, the FVC was lower (71% predicted) than in ACA patients, suggesting they had some interstitial fibrosis. However, they had a higher FVC%/diffusing capacity for carbon monoxide (DLCO)% ratio than the ACA patients (2.4 vs 1.8). pulmonary hypertension in TOPO patients was associated with a lower FVC%/DLCO% ratio and lower levels of PAP than either the PAH in ACA or ANoA patients.

CONCLUSION

Scleroderma-specific autoantibodies are associated with characteristic subgroups of lung disease. The ANoA patients have a unique mixture of PAH and SPF subgroups of lung disease. Scleroderma-specific autoantibodies and the FVC%/DLCO% ratio are helpful in determining whether a patient has PAH alone, PAH along with pulmonary fibrosis, or secondary PAH from chronic hypoxia with SPF.

Clinical subsets, skin thickness progression rate, and serum antibody levels in systemic sclerosis patients with anti-topoisomerase I antibody

OBJECTIVE

To describe the clinical and laboratory features and natural history of the disease in systemic sclerosis (SSc; scleroderma) patients with anti-topoisomerase I (anti-topo I) antibody who have different skin thickness progression rates (STPRs).

METHODS

SSc patients (n = 212) who were anti-topo I antibody positive were divided into 5 subgroups based on STPRs. Skin thickness was measured using the modified Rodnan skin thickness score (MRSS). Anti-topo I IgG antibody levels were determined.

RESULTS

Sixty patients who were anti-topo I antibody positive had diffuse cutaneous SSc (dcSSc) with rapid progression, 82 had dcSSC with intermediate progression, and 29 had dcSSc with slow progression, 14 had limited cutaneous SSc (lcSSc) that became dcSSc, and 27 had lcSSc that did not change throughout. Patients beginning with lcSSc were younger at disease onset and had longer disease duration when diagnosed as having SSc. Interstitial lung disease was common and was equally distributed across the subgroups. Renal crisis occurred most often in patients with rapid progression (22%) and was absent in lcSSc patients. Cardiac involvement was most frequent in the dcSSc subgroups. Both kidney and heart disease occurred most often within 3 years after the onset of skin thickening. The 10-year cumulative survival rate was <40% for patients with rapid and intermediate progression. Renal and cardiac causes of death were disproportionately frequent in these 2 subgroups. Anti-topo I antibody levels correlated with the STPR and the MRSS.

CONCLUSION

Anti-topo I antibody-positive patients with SSc with a rapid STPR have reduced survival rates, primarily due to early and often fatal renal and cardiac involvement. Anti-topo I antibody levels parallel the MRSS at the first visit and the STPR. This information is important for managing physicians and researchers planning clinical trials involving patients with early dcSSc.

Tumour necrosis factor-alpha single nucleotide polymorphisms are not independent of HLA class I in UK Caucasians with adult onset idiopathic inflammatory myopathies

OBJECTIVE

To investigate haplotype tagging single nucleotide polymorphisms (SNPs) in the tumour necrosis factor alpha (TNF-alpha) gene, in UK Caucasian idiopathic inflammatory myopathy (IIM) patients.

METHODS

A cross-sectional, case-control study of four TNF-alpha SNPs was undertaken, comparing cases of polymyositis (PM) (n = 121), dermatomyositis (DM) (n = 109) and myositis overlapping with other connective tissue diseases (CTD-overlap) (n = 73) with normal subjects (n = 177). Subgroup analyses were undertaken after stratifying for myositis specific/associated antibodies.

RESULTS

The TNF-308A allele demonstrated a strong association with each myositis disease subgroup vs controls [PM, odds ratio (OR) 2.8, 95% confidence interval 1.9-4.3; DM, OR 2.5, 1.6-3.8; CTD-overlap, OR 3.3, 2.1-5.1]. The TNF-308GA/AA genotype frequency was significantly increased vs controls (PM, OR 3.7, 2.1-6.3; DM, OR 3.2, 1.8-5.5; CTD-overlap, OR 5.0, 2.6-9.6) suggesting a dominant model. The association was strongest in patients possessing anti-aminoacyl transfer RNA synthetase (anti-synthetase) (OR 5.1, 3.3-8.0) or -PM-Scl (OR 5.0, 2.7-8.9) antibodies. The -1031T allele was also a significant risk factor in DM (OR 2.2, 1.4-3.6), anti-synthetase (OR 2.9, 1.6-5.3) and -PM-Scl (OR 5.6, 1.9-6.4) antibody positive patients. The TNF-308A association was lost after adjusting for HLA-B*08, but remained independent of HLA-DQB1*02 (both are alleles forming part of the common ancestral haplotype). The HLA-B*08/TNF-308A/DRB1*03/DQA1*05/DQB1*02 haplotype was a risk factor in all myositis subgroups vs controls (OR 3.0, 1.8-5.3).

CONCLUSIONS

TNF-308A and -1031T alleles are significant risk factors in the IIMs. In the IIMs, the TNF-308A allele is part of the common ancestral haplotype, but is not independent of HLA-B*08.

Interferon-gamma and interleukin-4 gene polymorphisms in Caucasian idiopathic inflammatory myopathy patients in UK

OBJECTIVE

To determine whether interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) genes confer susceptibility for the idiopathic inflammatory myopathies (IIMs).

METHODS

A large cross-sectional study of UK caucasian adults with polymyositis (PM, n = 101), dermatomyositis (DM, n = 94) and myositis overlapping with a connective tissue disease (myositis/CTD-overlap, n = 70) was completed. 177 ethnically matched controls were available for comparison. Single-nucleotide polymorphisms (SNPs) within intronic regions coding for IL-4, IFN-gamma and a microsatellite marker within intron 1 of the IFN-gamma gene were typed.

RESULTS

Strong linkage disequilibrium was present between SNPs in each gene. In the IFN-gamma gene, a weak allelic association was observed in PM versus controls at rs1861493 (odds ratio (OR) 1.6, 95% confidence interval (CI) 1.03 to 2.4). The microsatellite IFN-gamma CA(14) allele was associated with risk for IIMs overall (OR 3.3, 95% CI 1.4 to 7.8), the strongest association being observed within the anti-U1-ribonucleoprotein (RNP) group (OR 6.0, 95% CI 1.5 to 23.1), and persisting after adjustment for known myositis human leucocyte antigen (HLA) class II associations.

CONCLUSIONS

Genetic markers in the IFN-gamma gene demonstrate significant allelic associations with the IIMs in a UK Caucasian population. The SNPs tested in this study within the region coding for IL-4 fail to show significant associations with susceptibility to IIM disease.

The diagnostic utility of myositis autoantibody testing for predicting the risk of cancer-associated myositis

OBJECTIVES

There is a known association between myositis and cancer. The risk is greater in dermatomyositis (DM) than polymyositis (PM), although reliable methods to predict cancer risk in specific patients with myositis are not presently available. This study was undertaken to determine whether risk of developing cancer in myositis can be predicted by antibody profiling.

METHODS

A cross-sectional study of UK Caucasian adults with PM (n = 109), DM (n = 103) and connective tissue disease overlap (myositis/CTD-overlap, n = 70). Patients were tested for a comprehensive range of myositis-specific/associated autoantibodies. Sensitivity and specificity analyses were performed for the optimal identification of cancer risk.

RESULTS

Sixteen patients had cancer-associated myositis (CAM) (15 DM, 1 myositis/CTD-overlap). CAM patients were older at disease onset, and patients without myositis-specific/associated autoantibodies on "routine" laboratory testing (negative for anti-Jo-1, anti-PM-Scl, anti-U1-RNP, anti-U3-RNP, anti-Ku antibodies) had a significantly increased risk of CAM. Possession of the antibody against 155 kDa and 140 kDa protein specificities (anti-155/140 antibody) represented a significant risk factor for CAM, and was found exclusively in DM. A positive anti-155/140 antibody result proved highly specific, moderately sensitive, with high negative predictive value for CAM. A "negative routine myositis antibody panel" result was highly sensitive, with high negative predictive value for CAM. The combination of these two approaches was 94% sensitive, detecting 15 of 16 CAM, with 100% sensitivity and negative predictive value in DM.

CONCLUSIONS

These results may help clinicians predict which patients with myositis are at greater risk of developing cancer, thus identifying those requiring aggressive diagnostic evaluation and intensive cancer surveillance at myositis onset and follow-up.

In adult onset myositis, the presence of interstitial lung disease and myositis specific/associated antibodies are governed by HLA class II haplotype, rather than by myositis subtype

The aim of this study was to investigate HLA class II associations in polymyositis (PM) and dermatomyositis (DM), and to determine how these associations influence clinical and serological differences. DNA samples were obtained from 225 UK Caucasian idiopathic inflammatory myopathy patients (PM = 117, DM = 108) and compared with 537 randomly selected UK Caucasian controls. All cases had also been assessed for the presence of related malignancy and interstitial lung disease (ILD), and a number of myositis-specific/myositis-associated antibodies (MSAs/MAAs). Subjects were genotyped for HLA-DRB1, DQA1 and DQB1. HLA-DRB1*03, DQA1*05 and DQB1*02 were associated with an increased risk for both PM and DM. The HLA-DRB1*03-DQA1*05-DQB1*02 haplotype demonstrated strong association with ILD, irrespective of myositis subtype or presence of anti-aminoacyl-transfer RNA synthetase antibodies. The HLA-DRB1*07-DQA1*02-DQB1*02 haplotype was associated with risk for anti-Mi-2 antibodies, and discriminated PM from DM (odds ratio 0.3, 95% confidence interval 0.1-0.6), even in anti-Mi-2 negative patients. Other MSA/MAAs showed specific associations with other HLA class II haplotypes, irrespective of myositis subtype. There were no genotype, haplotype or serological associations with malignancy. The HLA-DRB1*03-DQA1*05-DQB1*02 haplotype associations appear to not only govern disease susceptibility in Caucasian PM/DM patients, but also phenotypic features common to PM/DM. Though strongly associated with anti-Mi-2 antibodies, the HLA-DRB1*07-DQA1*02-DQB1*02 haplotype shows differential associations with PM/DM disease susceptibility. In conclusion, these findings support the notion that myositis patients with differing myositis serology have different immunogenetic profiles, and that these profiles may define specific myositis subtypes.

Disease subsets, antinuclear antibody profile, and clinical features in 127 French and 247 US adult patients with systemic sclerosis

OBJECTIVE

To investigate the specificities of antinuclear antibodies (ANA) associated with systemic sclerosis (SSc) disease classification and internal organ involvement among patients with SSc of different origins (European and American).

METHODS

Serum samples from 374 adult patients diagnosed with SSc were studied: 127 French patients (Paris) were compared with 247 US patients (Pittsburgh). Patients were classified into diffuse cutaneous (dc) and limited cutaneous (lc) SSc subsets. Antibodies associated with SSc were determined by protein and/or RNA immunoprecipitation, indirect immunofluorescence, and immunodiffusion.

RESULTS

SSc classification differed significantly in the 2 cohorts: lcSSc and overlap patients with lcSSc combined made up 76% of the French series versus 52% of the US group (p < 0.0001). The frequency of anti-RNA polymerase III antibody was significantly increased in US patients compared with French patients (p < 0.0001). The frequency of anti-topoisomerase I (topo I) antibody was significantly increased among French patients (p < 0.0048). Anti-topo I-positive French SSc patients were less likely to have dcSSc (38% vs 65%) and more likely to have milder disease than US anti-topo I-positive patients. The French dcSSc patients had lower proportions of joint/tendon manifestations and renal crisis (7% vs 17%), but more often had radiographic evidence of pulmonary fibrosis (57% vs 30%). French lcSSc patients had a lower frequency of pulmonary arterial hypertension than US lcSSc patients (9% vs 31%; p = 0.002).

CONCLUSION

There are disease classification and SSc-related serum autoantibody differences between French and American patients with SSc. These differences help to explain variations in clinical features reported from different geographic regions.

Anti–Jo-1 antibody levels correlate with disease activity in idiopathic inflammatory myopathy

OBJECTIVE

Previous case series have examined the relationship between anti-Jo-1 antibody levels and myositis disease activity, demonstrating equivocal results. Using enzyme-linked immunosorbent assays (ELISAs) and novel measures of myositis disease activity, the current study was undertaken to systematically reexamine the association between anti-Jo-1 antibody levels and various disease manifestations of myositis.

METHODS

Serum anti-Jo-1 antibody levels were quantified using 2 independent ELISA methods, while disease activity was retrospectively graded using the Myositis Disease Activity Assessment Tool, which measures disease activity in 7 different organ systems via the Myositis Disease Activity Assessment Visual Analog Scale (VAS) and the Myositis Intention-to-Treat Index (MITAX) components. Spearman's rank correlation coefficients and mixed linear regression analysis were used to identify associations between anti-Jo-1 antibody levels and organ-specific disease activity in cross-sectional and longitudinal analyses, respectively.

RESULTS

Cross-sectional assessment of 81 patients with anti-Jo-1 antibody revealed a modest correlation between the anti-Jo-1 antibody level and the serum creatine kinase (CK) level, as well as muscle and joint disease activity. Correlation coefficients were similar for CK levels (r(s) = 0.38, P = 0.002), myositis VAS (r(s) = 0.36, P = 0.002), and arthritis VAS (r(s) = 0.40, P = 0.001). In multiple regression analyses of 11 patients with serial samples, anti-Jo-1 antibody levels correlated significantly with CK levels (R(2) = 0.65, P = 0.0002), myositis VAS (R(2) = 0.53, P = 0.0008), arthritis VAS (R(2) = 0.53, P = 0.006), pulmonary VAS (R(2) = 0.69, P = 0.005), global VAS (R(2) = 0.63, P = 0.002), and global MITAX (R(2) = 0.64, P = 0.0003).

CONCLUSION

In this large series of patients with idiopathic inflammatory myopathy, anti-Jo-1 antibody levels correlated modestly with muscle and joint disease, an association confirmed by a custom ELISA using recombinant human Jo-1. More striking associations emerged in a smaller longitudinal subset of patients that link anti-Jo-1 antibody levels to muscle, joint, lung, and global disease activity.

Monocyte chemotactic protein-1 single nucleotide polymorphisms do not confer susceptibility for the development of adult onset polymyositis/dermatomyositis in UK Caucasians

OBJECTIVES

Polymyositis (PM) and dermatomyositis (DM) form part of the idiopathic inflammatory myopathies (IIMs). The chemokine monocyte chemotactic protein-1 (MCP-1) is expressed at sites of the T cell inflammatory response in the IIMs. We thus investigate whether genetic markers in the MCP-1 gene confer disease susceptibility for the development of PM and DM.

METHODS

DNA samples were analysed from a group of 195 UK Caucasian IIM patients, comprising 103 PM and 92 DM. Their results were compared with those of 162 ethnically matched controls. The polymorphic positions of three single nucleotide polymorphisms (SNPs) and one insertion-deletion sequence within regions coding for MCP-1 were tested. The SNPs examined were located in intron 1 (rs2857657, C/G), exon 2 (rs4586, A/G) and the 3 ' untranslated region (rs13900, C/T). The insertion-deletion sequence was located in intron 1 (rs3917887, AGCTCCTCCTTCTC/-). Each SNP was tested for Hardy-Weinberg equilibrium and allelic/genotypic associations. Haplotype frequencies were estimated using the Expectation/Maximization algorithm.

RESULTS

There was strong linkage disequilibrium present between three out of these four markers. The majority of controls were in Hardy Weinberg equilibrium. No allelic, genotypic or haplotypic associations were detected when comparing PM or DM cases to controls, or when PM and DM were compared with each other.

CONCLUSIONS

Genetic markers in the MCP-1 gene do not demonstrate significant genetic associations with the IIMs, and do not discriminate PM from DM in a UK Caucasian population.

Childhood onset systemic sclerosis: classification, clinical and serologic features, and survival in comparison with adult onset disease

OBJECTIVE

To describe the differences between patients with systemic sclerosis (SSc) having childhood versus adult onset evaluated at a single medical center.

METHODS

Patients were divided into those with childhood onset (first SSc symptom or finding before age 16 yrs) and those with early adult and late adult onset. The 3 groups were compared with respect to disease classification, clinical, laboratory and serologic data, and survival.

RESULTS

One hundred eleven childhood onset SSc cases seen between 1960 and 2003 were compared with 2559 adult onset SSc cases (1087 with onset age 16-40 and 1472 with onset after age 40 yrs) first evaluated between 1972 and 2001. Age distribution at onset was unimodal, suggesting that childhood disease is part of the spectrum of adult onset SSc. A significantly greater proportion of childhood onset patients had overlap syndromes, most frequently with polymyositis-dermatomyositis (PM-DM), and skeletal muscle involvement. Children with diffuse cutaneous (dc) SSc had significantly lower maximum mean total skin thickness scores than adult patients with dcSSc. Renal involvement was uncommon in childhood onset cases, and the frequency increased with age of onset. Serum anti-PM-Scl and anti-U1RNP antibodies were detected significantly more frequently in childhood than in adult onset cases. In contrast, anti-RNA polymerase III and anticentromere antibodies were found significantly more frequently in adults. Survival was significantly better among childhood than all adult onset cases combined, but similar to survival in young adult onset SSc cases. Scleroderma heart disease was a frequent cause of death among children with SSc.

CONCLUSION

Patients with juvenile onset SSc more frequently have an overlap syndrome with PM-DM, higher frequency of skeletal muscle involvement, serum anti-PM-Scl and anti-U1RNP antibody, fatal cardiac disease, and improved survival compared with adult onset SSc cases.

Novel autoantibodies against 7SL RNA in patients with polymyositis/dermatomyositis

OBJECTIVE

Autoantibodies against signal recognition particle (SRP) are detected in patients with polymyositis/dermatomyositis (PM/DM). The SRP consists of 7SL RNA and 6 protein components. We examined autoantibodies against deproteinized 7SL RNA in PM/DM patients with anti-SRP antibodies and evaluated the association of anti-7SL RNA antibodies with PM/DM clinically and serologically.

METHODS

Sera from 10 Japanese and 22 North American PM/DM patients with anti-SRP antibodies were tested for the presence of anti-7SL RNA antibodies, using the sera to immunoprecipitate deproteinized RNA extracts derived from HeLa cells.

RESULTS

The immunoprecipitation analysis indicated that 5 Japanese (50%) and one North American (5%) patient with anti-SRP antibodies had novel autoantibodies against deproteinized 7SL RNA. The frequency of anti-7SL RNA antibodies was significantly higher in Japanese than North American patients (p = 0.006). The presence of anti-7SL RNA antibodies appeared to be associated with DM (2 patients) and finger swelling (2 PM patients). The seasonal onset of the disease was different (p = 0.008) for Japanese PM/DM patients with anti-7SL RNA antibodies, who developed the disease between October and January (mean month November; p = 0.01) from that of patients without these antibodies, who developed it between June and August (mean month July; p = 0.01).

CONCLUSION

Novel autoantibodies against 7SL RNA were identified in patients with PM/DM, and the presence of these antibodies was correlated to ethnic background, clinical features, and season of disease onset. These findings indicated that autoantibodies against 7SL RNA are a novel serological marker for a subset of PM/DM cases.

Enzyme-linked immunosorbent assay for detection of anti-RNA polymerase III antibody: analytical accuracy and clinical associations in systemic sclerosis

OBJECTIVE

We have recently developed an enzyme-linked immunosorbent assay (ELISA) for detection of anti-RNA polymerase III (anti-RNAP III) antibody, using a recombinant fragment containing the immunodominant epitope as the antigen source. This study was conducted to assess the analytical accuracy and clinical associations of the anti-RNAP III ELISA in patients with systemic sclerosis (SSc).

METHODS

To evaluate analytical sensitivity and specificity of the ELISA, both immunoprecipitation tests and ELISA were used to detect anti-RNAP III antibody in 534 SSc sera from patients at 3 medical centers. Sera from 522 SSc patients and 516 controls, including patients with other connective tissue diseases and blood bank donors, were also evaluated to assess the clinical sensitivity and specificity of the ELISA. Clinical findings in anti-RNAP III antibody-positive SSc patients were compared between patient groups stratified according to anti-RNAP III antibody levels determined by the ELISA.

RESULTS

In SSc patients, our ELISA showed analytical sensitivity of 91% and analytical specificity of 99% compared with the immunoprecipitation assay (a gold standard for detection of anti-RNAP III antibody). The additional analysis using a large series of SSc and control sera showed that clinical sensitivity and specificity of the ELISA with respect to the diagnosis of SSc were 17% and 98%, respectively. A high level of anti-RNAP III antibody was associated with diffuse cutaneous SSc, higher maximum total skin score, and increased frequency of tendon friction rubs.

CONCLUSION

The anti-RNAP III ELISA is analytically accurate and clinically specific. With this assay, testing for anti-RNAP III antibody can be made routinely available.

Cytotoxicity of colloidal CdSe and CdSe/ZnS nanoparticles

Cytotoxicity of CdSe and CdSe/ZnS nanoparticles has been investigated for different surface modifications such as coating with mercaptopropionic acid, silanization, and polymer coating. For all cases, quantitative values for the onset of cytotoxic effects in serum-free culture media are given. These values are correlated with microscope images in which the uptake of the particles by the cells has been investigated. Our data suggest that in addition to the release of toxic Cd(2+) ions from the particles also their surface chemistry, in particular their stability toward aggregation, plays an important role for cytotoxic effects. Additional patch clamp experiments investigate effects of the particles on currents through ion channels.

Treatment of antisynthetase-associated interstitial lung disease with tacrolimus

OBJECTIVE

To assess the efficacy of tacrolimus in patients with anti-aminoacyl-transfer RNA synthetase (anti-aaRS)-associated interstitial lung disease (ILD) and idiopathic inflammatory myopathy (IIM).

METHODS

Ninety-eight patients with anti-aaRS autoantibodies were identified in our IIM cohort of 536 patients. The medical records of 15 patients with anti-aaRS-associated ILD treated with tacrolimus between 1992 and 2003 were retrospectively reviewed. Pulmonary parameters of response included forced vital capacity, forced expiratory volume in 1 second, and diffusing capacity for carbon monoxide. Manual muscle testing results, serum creatine kinase (CK) levels, and the daily corticosteroid dosage were used to assess improvement in myositis. Random coefficient modeling considering polynomials of time was used to assess the clinical response to tacrolimus.

RESULTS

All patients, except for 1, who had pure ILD, had definite or probable IIM. Two patients received tacrolimus for fewer than 3 months, and their data were not analyzed. For the remaining 13 patients, the mean age at onset of ILD was 46.9 years, and the mean duration of pulmonary disease was 14.7 months. Twelve patients had anti-histidyl-transfer RNA synthetase autoantibody (anti-Jo-1) and 1 had anti-alanyl-transfer RNA synthetase autoantibody (anti-PL-12). Patients received tacrolimus for an average of 51.2 months. A significant improvement was observed in all pulmonary parameters measured. The serum CK level declined significantly, and 10 patients had either an improvement in muscle strength or maintained normal muscle strength. A statistically significant reduction in the corticosteroid dosage was also observed.

CONCLUSION

Tacrolimus is a well-tolerated and effective therapy for managing refractory ILD and myositis in anti-aaRS-positive patients.

Molecular Recognition Patterns of Serum Anti-DNA Topoisomerase I Antibody in Systemic Sclerosis

Autoreactive anti-DNA topoisomerase I (anti-Topo I) Abs are commonly detected in sera of systemic sclerosis (SSc) patients. Our studies have established a positive correlation between the levels of serum anti-Topo I Abs and both disease severity and activity of SSc. The molecular targets of anti-Topo I Ab on Topo I domains remain to be further defined. In this report, we studied the molecular recognition pattern of serum anti-Topo I Ab in 52 SSc patients. The highest reactivity of serum anti-Topo I Abs was against the core subdomains I and II (aa 207-441) and, to a lesser extent, against the core subdomain III (aa 433-636) of Topo I. The linker domain (aa 636-712) and the C-terminal domain (aa 713-765) had much less reactivity than the core domain (aa 207-636). Strikingly, very little reactivity was directed against the N-terminal domain (aa 1-213) by serum anti-Topo I Ab. This molecular recognition pattern was consistent among all SSc serum samples studied. Results from patients with serial serum samples indicated that this pattern remained unchanged over time. Interestingly, some naive B cells from healthy controls, upon transformation by EBV, produced IgM Abs against Topo I. These Abs had low affinity for Topo I and reacted equally to all domains of Topo I. The molecular recognition pattern of serum anti-Topo I Ab in SSc suggests the presence of a unique antigenic stimulation in vivo in this disease.

Genetic Control of Autoimmunity: Protection from Diabetes, but Spontaneous Autoimmune Biliary Disease in a Nonobese Diabetic Congenic Strain

At least 20 insulin-dependent diabetes (Idd) loci modify the progression of autoimmune diabetes in the NOD mouse, an animal model of human type 1 diabetes. The NOD.c3c4 congenic mouse, which has multiple B6- and B10-derived Idd-resistant alleles on chromosomes 3 and 4, respectively, is completely protected from autoimmune diabetes. We demonstrate in this study, however, that NOD.c3c4 mice develop a novel spontaneous and fatal autoimmune polycystic biliary tract disease, with lymphocytic peribiliary infiltrates and autoantibodies. Strains having a subset of the Idd-resistant alleles present in the NOD.c3c4 strain show component phenotypes of the liver disease: NOD mice with B6 resistance alleles only on chromosome 3 have lymphocytic liver infiltration without autoantibody formation, while NOD mice with B10 resistance alleles only on chromosome 4 show autoantibody formation without liver infiltration. The liver disease is transferable to naive NOD.c3c4 recipients using splenocytes from affected NOD.c3c4 mice, demonstrating an autoimmune etiology. Thus, substitution of non-NOD genetic intervals into the NOD strain can prevent diabetes, but in turn cause an entirely different autoimmune syndrome, a finding consistent with a generalized failure of self-tolerance in the NOD genetic background. The complex clinical phenotypes in human autoimmune conditions may be similarly resolved into largely overlapping biochemical pathways that are then modified, potentially by alleles at a few key chromosomal regions, to produce specific autoimmune syndromes.

Anti-signal recognition particle autoantibody in patients with and patients without idiopathic inflammatory myopathy

OBJECTIVE

To determine the long-term outcome and associated clinical, serologic, and pathologic features in a cohort of patients with connective tissue disease (CTD) and the anti-signal recognition particle (anti-SRP) autoantibody.

METHODS

Sera and clinical data were collected prospectively from consecutive adult patients with polymyositis (PM; n = 134), dermatomyositis (n = 129), or other CTDs (predominantly systemic sclerosis [SSc; n = 790]). Patients were first evaluated during 1973-2001.

RESULTS

Nineteen patients with the anti-SRP autoantibody were identified, 16 (84%) of whom had pure PM and 3 (2 with SSc and 1 with antisynthetase syndrome) had yet to develop features of myositis after a mean followup of 4.5 years (range 2.5-6 years). More SRP-positive PM patients had severe proximal muscle weakness (50%) and muscle atrophy (67%) at initial presentation compared with antisynthetase-positive PM controls. Cardiac involvement occurred in only 2 of 16 SRP-positive PM patients (13%), and interstitial lung disease was noted in 3 of 13 SRP-positive PM patients (23%) and in the 3 SRP-positive nonmyositis patients. There was a relative lack of inflammation in muscle biopsy specimens from the SRP-positive PM cohort. Other autoantibodies in the SRP-positive patients included Ro/SSA (4 patients), Th/To (1 patient), and anti-PL-12 (1 patient). Survival in the SRP-positive PM patients was comparable with that seen in the cohort of SRP-negative PM patients.

CONCLUSION

The anti-SRP autoantibody is not specific for PM. Severe muscle weakness and atrophy were prominent features in PM patients with anti-SRP. Cardiac involvement was less common and survival was better in patients with anti-SRP than has previously been reported.

Ion channel drug discovery and research: the automated Nano-Patch-Clamp technology

Unlike the genomics revolution, which was largely enabled by a single technological advance (high throughput sequencing), rapid advancement in proteomics will require a broader effort to increase the throughput of a number of key tools for functional analysis of different types of proteins. In the case of ion channels -a class of (membrane) proteins of great physiological importance and potential as drug targets- the lack of adequate assay technologies is felt particularly strongly. The available, indirect, high throughput screening methods for ion channels clearly generate insufficient information. The best technology to study ion channel function and screen for compound interaction is the patch clamp technique, but patch clamping suffers from low throughput, which is not acceptable for drug screening. A first step towards a solution is presented here. The nano patch clamp technology, which is based on a planar, microstructured glass chip, enables automatic whole cell patch clamp measurements. The Port-a-Patch is an automated electrophysiology workstation, which uses planar patch clamp chips. This approach enables high quality and high content ion channel and compound evaluation on a one-cell-at-a-time basis. The presented automation of the patch process and its scalability to an array format are the prerequisites for any higher throughput electrophysiology instruments.

High Quality Ion Channel Analysis on a Chip with the NPC© Technology

In evaluating ion channel function, electrophysiology, e.g., patch clamping, provides the highest information content. For the analysis of ion channel-modulating compounds, one variant of the patch-clamp technique, the whole-cell configuration, is particularly useful. We present here patch-clamp recordings in the whole-cell configuration and single channel recordings performed with planar patch-clamp chips, which are microstructured from borosilicate glass substrate. The chips are used in the Port-a-Patch, an ion channel research/screening instrument that enables automated patch-clamp experiments on a single cell. A software runs the experiment by executing user-determined protocols for cell positioning, as well as for electrical stimulation and current readout. In various electrophysiological experiments, the high quality of recordings and the versatility of the perfusion of the recorded cells are demonstrated. Quantitative pharmacological experiments are performed on sodium channels expressed in HEK cells using solution volumes in the low microliter range. The exceptionally low volume consumption in the experiments make the system attractive for work on rare or expensive compounds. Due to the low volumes necessary, a rapid solution exchange is facilitated, which is shown on RBL cells. The patch-clamp chip enables a rapid and precise perfusion, allowing sophisticated investigations on ion channel function with the Port-a-Patch.

Correlation of serum anti-DNA topoisomerase I antibody levels with disease severity and activity in systemic sclerosis

OBJECTIVE

To investigate correlations between serum levels of topoisomerase I-specific antibody (anti-topo I) and clinical features of systemic sclerosis (SSc), including disease severity (the total skin score [TSS]) and disease activity.

METHODS

Using highly sensitive enzyme-linked immunosorbent assays, we measured the levels of anti-topo I antibody, including total IgG, individual IgG subclasses, and IgA, and analyzed their correlations with the TSS in 59 patients with SSc, all of whom had diffuse cutaneous involvement. Serial serum samples were obtained from 11 of these patients.

RESULTS

The titers of anti-topo I antibody, including IgG and IgA, were positively correlated with the TSS, a measure of SSc disease severity. In 8 of the 11 patients from whom serial serum samples were obtained, changes in the levels of both IgG and IgA, when detectable, paralleled changes in the TSS. In 3 patients, an increasing anti-topo I IgG level preceded an increase in the TSS. The level of each IgG subclass also correlated with and tended to parallel the TSS. The patients with very active disease had higher mean IgG (P < 0.001) and IgA (P < 0.05) titers than did those with inactive disease.

CONCLUSION

Serum levels of anti-topo I antibody correlate positively with disease severity and disease activity in SSc.

A comparison between anti-Th/To- and anticentromere antibody-positive systemic sclerosis patients with limited cutaneous involvement

OBJECTIVE

To compare anti-Th/To-positive and anticentromere antibody (ACA)-positive patients with limited cutaneous systemic sclerosis (lcSSc).

METHODS

We reviewed the medical records of 107 anti-Th/To-positive patients and 365 ACA-positive patients who were first evaluated during 1985-2000. ACA was detected by indirect immunofluorescence on HEp-2 cell substrate, and anti-Th/To was detected by RNA immunoprecipitation with K562 cell extracts. Patients were included if they had a clinical diagnosis of lcSSc, and excluded if they had >1 SSc-associated serum autoantibody.

RESULTS

The final study groups comprised 87 lcSSc patients with anti-Th/To antibodies and 306 with ACAs. Anti-Th/To-positive patients were younger (P < 0.04) and had a shorter disease duration at their first evaluation (P < 0.003). Patients with anti-Th/To antibodies had more subtle skin changes, less severe vascular involvement, and less frequent distal esophageal hypomotility. Both groups had a higher frequency of "intrinsic" pulmonary hypertension than has been previously reported in the literature (28% and 19% of anti-Th/To-positive and ACA-positive patients, respectively), perhaps due to referral bias. Patients in the anti-Th/To group more often had radiographic evidence of interstitial lung disease (48% versus 13% of the ACA group; P < 0.0001). Scleroderma renal crisis was uncommon (4 cases), but occurred exclusively in the anti-Th/To group. Survival among the anti-Th/To-positive patients was reduced compared with that in the ACA group (P < 0.02).

CONCLUSION

Patients with anti-Th/To and those with ACA most often develop lcSSc and have a high frequency of "intrinsic" pulmonary hypertension. Compared with the ACA patients, anti-Th/To lcSSc patients have more subtle cutaneous, vascular, and gastrointestinal involvement, but more often have certain features typically seen in diffuse scleroderma, such as pulmonary fibrosis and scleroderma renal crisis, as well as reduced survival.

Simultaneous optical and electrical recording of single gramicidin channels

We report here an approach for simultaneous fluorescence imaging and electrical recording of single ion channels in planar bilayer membranes. As a test case, fluorescently labeled (Cy3 and Cy5) gramicidin derivatives were imaged at the single-molecule level using far-field illumination and cooled CCD camera detection. Gramicidin monomers were observed to diffuse in the plane of the membrane with a diffusion coefficient of 3.3 x 10(-8) cm(2)s(-1). Simultaneous electrical recording detected gramicidin homodimer (Cy3/Cy3, Cy5/Cy5) and heterodimer (Cy3/Cy5) channels. Heterodimer formation was observed optically by the appearance of a fluorescence resonance energy transfer (FRET) signal (irradiation of Cy3, detection of Cy5). The number of FRET signals was significantly smaller than the number of Cy3 signals (Cy3 monomers plus Cy3 homodimers) as expected. The number of FRET signals increased with increasing channel activity. In numerous cases the appearance of a FRET signal was observed to correlate with a channel opening event detected electrically. The heterodimers also diffused in the plane of the membrane with a diffusion coefficient of 3.0 x 10(-8) cm(2)s(-1). These experiments demonstrate the feasibility of simultaneous optical and electrical detection of structural changes in single ion channels as well as suggesting strategies for improving the reliability of such measurements.

Microstructured glass chip for ion-channel electrophysiology

We present a technique by which it is possible to produce a planar sensor for ion channel electrophysiology from glass substrates. Apertures with diameters in the low micrometer to submicrometer range are achieved by irradiation of a glass chip with a single heavy ion and subsequent wet track etching. The function of the device is demonstrated by recordings of single channel currents mediated by the model ion channel gramicidin A in lipid bilayers spanning the micromachined aperture.

Systemic sclerosis with renal crisis and pulmonary hypertension: a report of eleven cases

OBJECTIVE

To describe a series of systemic sclerosis (SSc) patients with the unusual combination of scleroderma renal crisis (SRC) and pulmonary hypertension (PHT) without interstitial lung disease.

METHODS

The medical records of 2,459 SSc patients in the University of Pittsburgh Scleroderma Databank first evaluated between 1972 and 1999 were reviewed.

RESULTS

Eleven patients (0.45%) had both SRC and PHT. All had been evaluated since 1979, when angiotensin-converting enzyme (ACE) inhibitor therapy for SRC became available. Seven had SSc with limited cutaneous involvement, and 4 had SSc with diffuse cutaneous involvement. SRC occurred first in all patients except 1, in whom the onsets of SRC and PHT were simultaneous. SRC preceded PHT by a mean of 4.3 years. Four patients had anti-Th/To antibody, 5 had anti-RNA polymerase III antibody, 2 had anti-U3 RNP antibody, and none had anticentromere or antitopoisomerase I antibody. Ten of the 11 patients died, 8 from PHT. Ten patients were being treated with ACE inhibitor drugs when PHT developed.

CONCLUSION

In SSc, SRC and PHT are not mutually exclusive complications. SSc patients surviving SRC who have serum antibodies to Th/To, RNA polymerase III, or U3 RNP are at increased risk to develop PHT. ACE inhibitor therapy did not prevent the development of PHT.

Isolated pulmonary hypertension in diffuse cutaneous systemic sclerosis successfully treated with long-term plasma exchange

Isolated pulmonary hypertension (PHT) in patients with diffuse cutaneous systemic sclerosis (dSSc) is one of the most severe complication. Here we report the case of a 22 year-old white woman with anti-U3RNP antibody-positive dSSc complicated by severe, isolated PHT successfully treated with long-term plasma exchange. This beneficial effect persisted for two years, even after plasma exchange discontinuation. This is the first observation of isolated PHT in dSSc responsive to plasma exchange therapy.

Studies of HLA-DR and DQ alleles in systemic sclerosis patients with autoantibodies to RNA polymerases and U3-RNP (fibrillarin)

OBJECTIVE

To determine the clinical and immunogenetic features of systemic sclerosis (SSc) patients with anti-RNA polymerase (RNAP) or anti-fibrillarin antibodies.

METHODS

DNA typing for HLA-DR and DQ alleles was performed in 292 patients with SSc, including 81 with anti-RNAP and 24 with anti-fibrillarin antibodies. The remaining patients had anti-topoisomerase I (anti-topo I; 71), anti-centromere (ACA; 56), anti-Th/To (28), or other antinuclear (32) antibodies.

RESULTS

Significant associations were observed in the patients with anti-topo I, ACA, and anti-Th/To antibodies, similar to those previously reported. No significant HLA associations were detected in the 81 patients with anti-RNAP. although weak associations were noted when this group was subdivided on the basis of immunofluorescence staining pattern; i.e., HLA-DR4 was increased in patients with strong nucleolar staining and HLA-DR3 was more frequent in patients with nucleoplasm staining only. No HLA-DR or DQ associations were observed in 24 patients with anti-fibrillarin antibodies.

CONCLUSION

The identification of HLA associations in SSc patients with anti-RNAP antibodies may only be possible when the individual antibody specificities recognized by these sera are identified. It may then be possible to classify these patients into distinct clinical and immunogenetic subgroups.