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FRI0389 First report of anti-mda5 antibodies in a cohort of italian patients with dermatomyositis: clinical and serologic correlations
  1. A. Ceribelli1,
  2. M. Fredi2,
  3. I. Cavazzana3,
  4. M. Taraborelli2,
  5. A. Tincani2,
  6. C. Selmi4,
  7. E. K. Chan5,
  8. M. Satoh6,
  9. F. Franceschini3
  1. 1Rheumatology and Clinical Immunology, Humanitas clinical and research center and BIOMETRA department, University of Milan, Milan, Italy, Rozzano
  2. 2Rheumatology and Clinical Immunology, Spedali Civili, Universita’ degli Studi, Brescia
  3. 3Rheumatology and Clinical Immunology, Spedali Civili, Brescia
  4. 4Rheumatology and Clinical Immunology, Humanitas clinical and research center, University of Milan, University of California at Davis, Rozzano (MI), Italy
  5. 5Oral Biology
  6. 6Medicine, Division of Rheumatology, University of Florida, Gainesville, United States

Abstract

Background Polymyositis/dermatomyositis (PM/DM) are autoimmune diseases characterized by skin and muscle inflammation, internal organs involvement and presence of myositis-specific antibodies (MSAs). In recent years, new MSAs have been identified in association with specific clinical features, as anti-CADM140/MDA5 (melanoma differentiation-associated gene 5), -TIF1gamma/alpha (p155/140) and -MJ/NXP-2. Among these, anti-MDA5 antibodies are strongly associated with clinically amyopathic DM (CADM), rapidly progressive interstitial lung disease (RPILD), severe skin manifestations and worse prognosis. In most cases, anti-MDA5 antibodies are detected in Eastern Asian (Japan, Korea, and China) cohorts, with the exception of only one American study.

Objectives The aim of our work is to identify anti-MDA5 antibodies and their clinical associations in a cohort of Italian (European Caucasian) patients with PM/DM.

Methods Sera of 79 consecutive adult Italian (European Caucasian) patients with PM/DM were collected in the outpatient clinic of the Rheumatology Unit in Brescia (Spedali Civili) in 2009-2012. The criteria of Bohan and Peter for PM/DM and the criteria of Sontheimer for CADM were used to establish the diagnosis. All MSAa were characterized by immunoprecipitation (IP) of 35S-methionin radiolabeled K562 (human erythroleukemia) cell extract except anti-MDA5; anti-MDA5 was confirmed by ELISA (recombinant MDA5 protein and 1:250 diluted sera) and immunoprecipitation-Western Blot (IP-WB) using rabbit anti-MDA5 antibodies. Clinical information were obtained from clinical charts.

Results Anti-MDA5 antibodies were identified in 6/79 (8%) PM/DM cases, and they were the second most common specificity after anti-MJ (8/79; 10%); 23% (8/35) DM and 20% (16/79) in the whole PM/DM cohort still did not have known myositis antibodies. Anti-MDA5 was found in 17% (6/35) in DM and 5/6 cases were CADM, indicating strong association between anti-MDA5 and CADM. The clinical features of 6 anti-MDA5 (+) DM cases were analyzed vs 29 anti-MDA5 (-) DM. Compared to anti-MDA5 (-) DM, anti-MDA5 (+) have severe skin disease, mainly represented by skin ulcers (digit pulp/periungual and Gottron’s lesions) and heliotrope rash (67% vs 55%). ILD is more common in the anti-MDA5 (+) DM patients (50%) vs anti-MDA5 (-) (14%): two patients underwent cyclophosphamide therapy, and one died due to RPILD. One also developed subcutaneous emphysema with pneumomediastinum. 83% of anti-MDA5 (+) had CADM (vs 17% CADM in anti-MDA5 (-); p=0.004). Only one anti-MDA5 (+) patient had moderate increase of CPK and muscle weakness. No significant association was identified between anti-MDA5 antibodies and other DM symptoms, such as Raynaud’s phenomenon, oral ulcers, calcinosis and higher risk of cancer-associated DM. None of anti-MDA5 (+) cases had other MSAs.

Conclusions Our study is the first report on anti-MDA5 antibodies in adult Italian (European Caucasian) patients with PM/DM. Anti-MDA5 antibodies were detected in 8% (6/79) Italian PM/DM, all affected by DM. Anti-MDA5 antibodies are not specific for Asian patients but they are also common in Italian patients with CADM.

Disclosure of Interest: None Declared

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