A New Enzyme-Linked Immunosorbent Assay System for Detecting Autoantibodies to Aminoacyl-tRNA Synthetases: Clinical Usefulness in Myositis and Interstitial Pneumonia

Ran Nakashima¹, Yoshitaka Imura², Minae Seto³, Akihiro Murakami³, Yuji Hosono⁴, Kizuku Watanabe⁵, Tomohiro Handa⁵, Michiaki Mishima⁵, Michito Hirakata⁶, Tsutomu Takeuchi⁷, Keishi Fujio⁸, Kazuhiko Yamamoto⁹, Hitoshi Kohsaka¹⁰, Yoshinari Takasaki¹¹, Noriyuki Enomoto¹², Kingo Chida¹², Toshihiro Nukiwa¹³ and Tsuneyo Mimori¹, ¹Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto, Japan, ²Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, Kyoto, Japan, ³Medical & Biological Laboratories Co., Ltd., Ina, Japan, ⁴Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, Kyoto, Japan, ⁵Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan, Kyoto, Japan, ⁶Internal Medicine, Keio University, Tokyo, Japan, ⁷Keio University School of Medicine, Tokyo, Japan, ⁸Department of Allergy and Rheumatology, The University of Tokyo, Tokyo, Japan, ⁹Department of Allergy & Rheumatology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan, ¹⁰Department of Medicine and Rheumatology, Tokyo Medical and Dental University, Tokyo, Japan, ¹¹Division of Rheumatology, Department of Internal Medicine, Juntendo University, Tokyo, Japan, ¹²Hamamatsu University School of Medicine, Hamamatsu, Japan, ¹³Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan

Meeting: 2012 ACR/ARHP Annual Meeting

Keywords: autoantibodies, Biomarkers, diagnosis and polymyositis/dermatomyositis (PM/DM)

Session Information

Title: Muscle Biology, Myositis and Myopathies: Genetics, Autoantibodies and other Molecular Aspects of Idiopathic Inflammatory Myopathies and Models

Session Type: Abstract Submissions (ACR)

Background/Purpose: Autoantibodies to aminoacyl-tRNA synthetases (ARS) are the most frequent myositis-specific antibodies and they are useful in the diagnosis and management of polymyositis (PM)/ dermatomyositis (DM) and interstitial pneumonia (IP). However, routine detection of all of them at once is not available. We developed an enzyme-linked immunosorbent assay (ELISA) system using a mixture of recombinant ARS antigens to detect them easily and simultaneously. We tested the usefulness of this system for diagnosing PM/DM and IP in the multicenter study.

Methods: We prepared 6 recombinant ARS antigens; GST-Jo-1, His-PL-12, His-EJ and GST-KS expressed in Eschericha coli, and His-PL-7 and His-OJ expressed in Hi-5 cells. After confirming antigenic activity of all the recombinant proteins except His-OJ, using immunoblotting or ELISA, we made an ELISA system mixing the five recombinant ARS antigens. Efficiency was confirmed using the sera from 549 Japanese patients with various connective tissue diseases (PM/DM 273, systemic lupus erythematosus (SLE) 91, systemic sclerosis (SSc) 70, rheumatoid arthritis (RA) 75, Sjӧgren’s syndrome (SS) 27 and other diseases 13), 170 idiopathic IP (IIP) and 30 healthy controls collected from 8 institutes. IIP was classified into two groups according to the radiologic pattern, usual interstitial pneumonia (UIP) (n=36) and non-UIP (n=132). Results were compared with those of the standard RNA immunoprecipitation assay.

Results: All of the ELISA results were consistent with those of the immunoprecipitation assay, except for one false-positive sample. Sensitivity and specificity were 100% and 99.8%, respectively when compared with the RNA immunoprecipitation. Anti-ARS antibodies were detected in 34.8% of PM/DM, 2.2% of SLE, 2.9% of SSc, 4% of RA, 0% of SS and 10.6% of IIP. None of the healthy controls were positive for anti-ARS antibodies. The frequency of each anti-ARS antibodies was compatible with previous reports. Anti-ARS-positive PM/DM patients had IP much more frequently than anti-ARS-negative PM/DM patients (87.3% vs. 48.6% respectively, p<0.001). In IIP, anti-ARS antibodies were positive in 5.6% of UIP and 12.1% of non-UIP. Anti-ARS-positive IIP patients were younger and more frequently treated with corticosteroids and/or immunosuppressants than anti-ARS-negative patients.

Conclusion: A newly established anti-ARS ELISA system detected anti-ARS antibodies as efficiently as RNA immunoprecipitation. This system will enable the easier and wider detection of anti-ARS antibodies in patients with PM/DM and IP in daily practice.

Disclosure:

R. Nakashima,
None;

Y. Imura,
None;

M. Seto,

Medical & Biological Laboratories, Co., Ltd.,

A. Murakami,

Medical & Biological Laboratories, Co., Ltd.,

Y. Hosono,
None;

K. Watanabe,
None;

T. Handa,
None;

M. Mishima,
None;

M. Hirakata,
None;

T. Takeuchi,
None;

K. Fujio,
None;

K. Yamamoto,
None;

H. Kohsaka,

Chugai Pharma, Ajinomoto Pharma & Teijin Parma,

Y. Takasaki,
None;

N. Enomoto,
None;

K. Chida,
None;

T. Nukiwa,
None;

T. Mimori,

Medical & Biological Laboratories, Co., Ltd.,

Medical & Biological Laboratories, Co., Ltd,

« Back to 2012 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-new-enzyme-linked-immunosorbent-assay-system-for-detecting-autoantibodies-to-aminoacyl-trna-synthetases-clinical-usefulness-in-myositis-and-interstitial-pneumonia/