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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Autoantibodies to RuvBL1 and RuvBL2: a novel systemic sclerosis-related antibody associated with diffuse cutaneous and skeletal muscle involvement.

OBJECTIVE: To identify and characterize a novel systemic sclerosis (SSc)-related autoantibody directed against a complex consisting of RuvBL1 and RuvBL2 (RuvBL1/2) and to assess its clinical correlations. METHODS: We first analyzed 316 consecutive patients with SSc who were evaluated at Kanazawa University Hospital. Controls included 290 patients with other connective tissue diseases, interstitial lung disease alone, or autoimmune hepatitis, and 50 healthy subjects. Autoantibody specificities were analyzed using RNA and protein immunoprecipitation assays. Autoimmune targets were affinity purified using patients' sera and subjected to liquid chromatography mass spectrometry. SSc patients in another institution in Japan and the University of Pittsburgh cohort were also included in analysis for evaluating clinical correlations. RESULTS: By protein immunoprecipitation assay, 6 SSc sera (1.9%) reacted with doublets with molecular weights of ∼50 kd. Liquid chromatography mass spectrometry of the partially purified autoantigen and additional immunoblot-based analyses revealed that this antibody specificity recognized RuvBL1/2. Anti-RuvBL1/2 antibody was exclusively detected in SSc patients. SSc patients with anti-RuvBL1/2 in both the Japanese and Pittsburgh cohorts consistently had higher frequencies of SSc in overlap with myositis and diffuse skin thickening than those without anti-RuvBL1/2. Compared with other autoantibodies related to SSc/myositis overlap (anti-PM-Scl and anti-Ku), anti-RuvBL1/2 was distinctive in terms of its associations with older age at SSc onset, male sex, and a high frequency of diffuse cutaneous involvement. CONCLUSION: Anti-RuvBL1/2 antibody is a novel SSc-related autoantibody associated with a unique combination of clinical features, including myositis overlap and diffuse cutaneous involvement.

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.

Clinical and serologic characterization of an Argentine pediatric myositis cohort: identification of a novel autoantibody (anti-MJ) to a 142-kDa protein.

OBJECTIVE: Autoantibodies are frequently found in adult patients with polymyositis (PM), dermato-myositis (DM), and overlap myositis disorders. They are less common in pediatric patients with myositis. We investigated the autoantibody pattern in a pediatric Argentine Caucasian cohort to characterize novel autoantibodies. METHODS: Sera from children that satisfied published criteria for idiopathic inflammatory myopathy were analyzed for autoantibodies by RNA and protein immunoprecipitation and immunoblotting techniques. Routine myositis-specific and myositis-associated autoantibodies as well as autoantibody specificities were determined. RESULTS: We tested sera from 64 consecutive pediatric myositis patients, including 40 with juvenile DM, 7 with juvenile PM, and 17 with overlap myositis syndromes. Sixteen (25%) patients were found to have anti-MJ autoantibody exclusively, which appears to identify a subset of pediatric myositis patients with severe disease characterized by muscle contractures and atrophy and significant compromise of functional status. Fourteen (22%) patients were found to have an antibody targeting 2 proteins of 155 and 140 kDa. Other myositis-specific autoantibodies were uncommon in this pediatric cohort. CONCLUSION: A newly recognized autoantibody, anti-MJ, was the most common antibody found in this Argentine pediatric cohort. The clinical features indicated that this antibody is distinct from other reported antibodies in pediatric patients with myositis.

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.

Serum autoantibodies and their clinical associations in patients with childhood- and adult-onset linear scleroderma. A single-center study.

OBJECTIVE: To determine the frequency of selected serum autoantibodies and their clinical associations in patients with childhood-onset (ChO) or adult-onset (AO) linear scleroderma (LiScl) evaluated at a single institution. METHODS: Seventy-two patients (ChO = 40, AO = 32), including 12 with en coup de sabre, were studied. All ChO patients had disease onset before age 16 years. Clinical features (extent of cutaneous disease, activity, and joint contractures) were recorded. Antinuclear antibodies (ANA) were identified by indirect immunofluorescence (HEp-2 cells), and anti-single-stranded DNA (anti-ssDNA), antihistone (AHA), and antichromatin (AChA) autoantibodies were detected by ELISA. RESULTS: There were no significant differences between groups in regard to gender, proportion with LiScl/E, or clinical features except joint contractures (ChO > AO; p = 0.04). There were no differences in the frequency of ANA or other autoantibodies between the groups except for AHA (ChO > AO). AHA was more frequently found with anti-ssDNA (p < 0.0001). LiScl patients with positive anti-ssDNA and/or AHA had more extensive cutaneous involvement and more often had joint contractures (p < 0.05). Anti-ssDNA was present more frequently in AO than in ChO patients with active lesions (p = 0.04). ANA and AChA were not associated with any clinical features. Both AHA and anti-ssDNA levels showed good correlation with disease severity. CONCLUSION: Over two-thirds of LiScl patients had ANA. Patients with ChO were similar to those with AO with regard to the frequency of selected serum autoantibodies. Anti-ssDNA and AHA were frequently found together and both were associated with more extensive skin disease with joint contractures. LiScl disease severity correlated with the serum levels of both these antibodies.

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.

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.