Date: Monday, October 22, 2018
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Many kinds of autoantibodies are detected in idiopathic inflammatory myopathy (IIM) patients. Some of them are useful to diagnose, predict the clinical course, and assess therapy in IIM at an early stage. Here we describeand characterize the clinical significance of a novel autoantibody in IIM directed against the DNA damage binding protein1.
Three-hundred and eighty patients with various connective tissue diseases (CTDs) and 20 healthy controls (HCs) were screened for autoantibodies by immunoprecipitation with [35S]methionine-labeled HeLa cells. The target autoantigen was immunoaffinity-purified from HeLa cell extracts and was subsequently identified by peptide mass fingerprinting. Antigen specificity of the serum was further examined by immunoblotting.
An antibody directed against a 120kDa protein was detected in serum from 6 patients with IIM, but not in theserum of other CTD patients or HCs. No patient with anti-120kDa antibodies was positive for other myositis-specific autoantibodies. 50% (3 of 6) were underwent a muscle biopsy compatible with inflammatory myopathy. Most anti-DDB1 positive patients (4 of 6, 67%) showed spontaneous improvements without immunosuppressant treatment. Peptide mass fingerprintingidentified the DNA damage binding protein-1 (DDB1) as the autoantigen recognized by anti-120KDa autoantibodies. Immunoblotting experiments using recombinant full-length DDB1 protein confirmed that this was the autoantigen recognized by the anti-120KDa autoantibodies.
Anti-DDB1 antibodies are found in mild forms of IIM. Its detection may be helpful for diagnosis and have prognostic and therapeutic implications in patients with IM. This finding may shed new insights into the pathogenesis of IIM.
To cite this abstract in AMA style:Hosono Y, Nakashima R, Kitagori K, Murakami K, Yoshifuji H, Ohmura K, Mimori T. A Novel Autoantibody Against DNA Damage Binding Protein-1 in Idiopathic Inflammatory Myopathy [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/a-novel-autoantibody-against-dna-damage-binding-protein-1-in-idiopathic-inflammatory-myopathy/. Accessed October 25, 2021.
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