Low prevalence of anti-small ubiquitin-like modifier activating enzyme antibodies in dermatomyositis patients

Abstract

Background. The myositis-specific autoantibodies that characterize certain forms of inflammatory myopathy are useful in diagnosing dermatomyositis (DM) / polymyositis and predicting its prognosis. Autoantibodies to small ubiquitin-like modifier activating enzyme (SAE) have been identified as a DM-marker antibody in European Caucasians. Objective and methods. This study investigates the frequency and clinical characteristics of anti-SAE autoantibodies in Japanese patients with DM. Sera from 110 Japanese patients, including 13 with juvenile DM, were screened for anti-SAE antibodies by enzyme-linked immunosorbent assays. Positive sera were further examined by immunoblotting of the immunoprecipitates. Results. Only two patients (1.8%) were confirmed to have anti-SAE antibodies, and neither of these two patients had amyopathic or juvenile DM. One patient with anti-SAE had DM complicated with pulmonary arterial hypertension, and the other had cancer-associated DM. Both had hallmark cutaneous manifestations of DM. Conclusion. This is the first report of anti-SAE antibodies from an Asian single center cohort. Although Japanese patients with anti-SAE antibodies have a clinical phenotype similar to that of Caucasian patients, their frequency was lower in the Japanese patients than in the previously reported Caucasian patients.

Keywords::

• Anti-SAE antibody
• dermatomyositis
• ELISA
• immunoprecipitation Western blotting
• small ubiquitin-like modifier activating enzyme

Acknowledgements

We thank Dr. Akihiro Hirashiki in the Department of Cardiology, Nagoya University Graduate School of Medicine, for performing the cardiac catheterization.

Declaration of interest: This work was supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (23591618 to YM and 23249058 to MA) and a grant from the Ministry of Health, Labour and Welfare of Japan (to YM). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.