Date: Saturday, November 12, 2022
Session Title: Muscle Biology, Myositis and Myopathies Poster I
Session Type: Poster Session A
Session Time: 1:00PM-3:00PM
Background/Purpose: In idiopathic inflammatory myopathy (IIM), many kinds of autoantibodies are often detected and associated with each clinical phenotype. Recently, autoantibody against transcription factor Sp4 (anti-SP4) was newly discovered in IIM patient sera. However, whole clinical picture of anti-SP4 antibody-positive IIM is still unclear. Thus, the purpose of this study was to confirm the detection of anti-SP4 antibodies in IIM patients and investigate the clinical and serological features.
Methods: Adult Japanese IIM patients (N=201) who were treated at Tokai University hospital from 2012 to 2021 and healthy controls/non- systemic autoimmune rheumatic diseases (N=33) were enrolled. Anti-ARS, SRP Ab were screened by RNA-immunoprecipitation and anti-MDA5, Mi-2, HMGCR, Ku and TIF-1 Ab were detected by immunoprecipitation with [35S]methionine-labeled HeLa cells. Anti-SP4 was detected by immunoprecipitation and an enzyme-linked immune absorption assay. Clinical data was retrospectively collected.
Results: Among IIM patients,61% with antisynthetase syndrome, 17% with anti-MDA5, 13% with anti-TIF1γ,4% with anti-SRP, 2% with anti-Mi-2, 0.5% with anti-Ku, 0.5% with anti-HMGCR and 2.5% without any known autoantibodies. Anti-Sp4 autoantibodies was detected in 12.5% of DM and 1% of PM. Among DM patients, 55% (5/11) of anti-Sp4 autoantibodies were detected in patients with anti- anti-TIF1γ, 36% (4/11) were in anti-MDA5 and 18% (2/11) were in anti-Mi-2 autoantibodies. None of anti-SP4 autoantibody-positive DM patients had cancer. Among anti- anti-TIF1γ-positive DM patients, none of patients with coexisting anti-Sp4 had cancer, while 60% of those without anti-SP4 had (0% vs. 60%; p< 0.05, Chi-squared test).
Conclusion: In our study, anti-SP4 autoantibodies were frequency detected in PM/DM patients, and None of anti-SP4 autoantibody-positive DM patients had cancer. Coexisting of anti-SP4 autoantibodies may reduce the risk of malignancy in IIM patients, and screening for anti-SP4 autoantibodies is recommended at the diagnosis of IIM.
To cite this abstract in AMA style:Hosono Y, Kojima A, Ishii A, Sugiyama M, Izumi Y, Sasaki N, Yamada C, Sato S. Detection of the Novel Autoantibodies Against Transcription Factor Sp4 Is Related with Low Risk of Cancer in Idiopathic Inflammatory Myopathy Patients [abstract]. Arthritis Rheumatol. 2022; 74 (suppl 9). https://acrabstracts.org/abstract/detection-of-the-novel-autoantibodies-against-transcription-factor-sp4-is-related-with-low-risk-of-cancer-in-idiopathic-inflammatory-myopathy-patients/. Accessed May 27, 2023.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/detection-of-the-novel-autoantibodies-against-transcription-factor-sp4-is-related-with-low-risk-of-cancer-in-idiopathic-inflammatory-myopathy-patients/