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Systemic sclerosis (SSc) is a clinically heterogeneous autoimmune disease characterized by mutually exclusive autoantibodies directed against distinct nuclear antigens. We examined HLA associations in SSc and its autoantibody subsets in a large, newly recruited African American (AA) cohort and among European Americans (EA). In the AA population, the African ancestry-predominant HLA-DRB1 * 08:04 and HLA-DRB1 * 11:02 alleles were associated with overall SSc risk, and the HLA-DRB1 * 08:04 allele was strongly associated with the severe antifibrillarin (AFA) antibody subset of SSc (odds ratio = 7.4). These African ancestry-predominant alleles may help explain the increased frequency and severity of SSc among the AA population. In the EA population, the HLA-DPB1 * 13:01 and HLA-DRB1 * 07:01 alleles were more strongly associated with antitopoisomerase (ATA) and anticentromere antibody-positive subsets of SSc, respectively, than with overall SSc risk, emphasizing the importance of HLA in defining autoantibody subtypes. The association of the HLA-DPB1 * 13:01 allele with the ATA + subset of SSc in both AA and EA patients demonstrated a transancestry effect. A direct correlation between SSc prevalence and HLA-DPB1 * 13:01 allele frequency in multiple populations was observed ( r = 0.98, P = 3 × 10 -6 ). Conditional analysis in the autoantibody subsets of SSc revealed several associated amino acid residues, mostly in the peptide-binding groove of the class II HLA molecules. Using HLA α/β allelic heterodimers, we bioinformatically predicted immunodominant peptides of topoisomerase 1, fibrillarin, and centromere protein A and discovered that they are homologous to viral protein sequences from the Mimiviridae and Phycodnaviridae families. Taken together, these data suggest a possible link between HLA alleles, autoantibodies, and environmental triggers in the pathogenesis of SSc., Competing Interests: Competing interest statement: M.D.M. received consulting fees from Mitsubishi Tanabe, Astellas, Boehringer Ingelheim, Gerson Lehrman Group, Smart Analyst, and Guidepoint Global. R.T.D. received consulting fees from Eicos Sciences. D.K. received consulting fees from Actelion, Bristol-Myers Squibb, CSL Behring, Inventiva, EMD Merck-Serono, Sanofi-Aventis, GlaxoSmithKline, Corbus, Cytori, UCB, Bayer, Boehringer Ingelheim, and Genentech-Roche, and research support from Bayer, Bristol-Myers Squibb, and Pfizer, and owns stock or stock options in Eicos Sciences, Inc. (CiViBioPharma, Inc.). L.A.S. received consulting fees from Axon Pharma. H.G. received consulting fees from Pfizer, AbbVie, Actelion, and Horizon Pharmaceuticals. C.T.D. received research support from Gilead, Actelion, and Cytori. V.K.S. received research support from AbbVie. E.J.B. received consulting fees from Genentech. L.C. received consulting fees or served on the board of Reata, Bristol-Myers Squibb, Boehringer-Ingelheim, Eicos, and Mitsubishi Tanabe. S.L.B. and M.J.D. are coauthors on a 2015 research article., (Copyright © 2020 the Author(s). Published by PNAS.)

Objective: To examine the association of anti-RNPC-3 antibodies in patients with systemic sclerosis (scleroderma or SSc) with selected gastrointestinal (GI) tract complications., Methods: Sera from patients with SSc with or without severe GI dysfunction (total parenteral nutrition dependence) from the Johns Hopkins Scleroderma Center were screened for anti-RNPC-3 antibodies. We then examined anti-RNPC-3-positive cases and negative SSc controls from the University of Pittsburgh and the University of Pittsburgh Medical Center (UPMC) scleroderma cohort to confirm our findings and to examine whether specific GI features were associated with anti-RNPC-3 antibodies., Results: In the discovery cohort, patients with SSc with severe GI dysfunction (n = 37) and without GI dysfunction (n = 38) were screened for anti-RNPC-3 antibodies. The former were more likely to have anti-RNPC-3 antibodies (14% versus 3%; P = 0.11). In the Pittsburgh cohort, moderate-to-severe GI dysfunction (Medsger GI score ≥2) was present in 36% of anti-RNPC-3-positive patients versus 15% of anti-RNPC-3-negative patients (P ≤ 0.01). Anti-RNPC-3-positive patients were more likely to be male (31% versus 15%; P = 0.04), African American (18% versus 6%; P = 0.02), have esophageal dysmotility (93% versus 62%; P < 0.01), and interstitial lung disease (ILD) (77% versus 35%; P < 0.01). After adjusting for relevant covariates and potential confounders, moderate-to-severe GI disease was associated with anti-RNPC-3 antibodies (odds ratio [OR] 3.8 [95% confidence interval (95% CI) 1.0-14.3]), and ILD trended toward significance (OR 2.8 [95% CI 1.0-8.2])., Conclusion: Patients with SSc and anti-RNPC-3 antibodies are more likely to be male and African American and to have moderate-to-severe GI disease and ILD. Further studies on larger patient cohorts may be helpful in further defining subsets of patients with SSc at risk for severe GI involvement., (© 2018, American College of Rheumatology.)

Purpose of Review: To discuss recent advances in serologic testing for systemic sclerosis (SSc)-associated antibodies with respect to the diagnosis and prognosis of the disease., Recent Findings: The importance of SSc antibodies for diagnosis has become increasingly recognized, as evidenced by incorporation into the 2013 American College of Rheumatology/the European League Against Rheumatism clinical classification criteria for SSc. Two new SSc-associated antibodies and their clinical associations have been described. Multiple cohort studies have reported variable antibody frequency distribution based on geography, but the clinical associations remain much the same. New associations include anti-RNA polymerase III antibodies with gastric antral vascular ectasia, and a temporal association between SSc onset and RNA polymerase III antibodies., Summary: The role and associations of SSc-associated antibodies for diagnosis and internal organ involvement are becoming increasingly accepted.

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., (Copyright © 2012 by the American College of Rheumatology.)

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.

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.