Anti-MJ/NXP-2 autoantibody specificity in a cohort of adult Italian patients with polymyositis/dermatomyositis.

Abstract

INTRODUCTION:

Autoantibodies in patients with polymyositis/dermatomyositis (PM/DM) are associated with unique subsets, clinical course and outcome. Anti-MJ antibodies, which recognize the nuclear protein NXP-2/MORC3, are reported in ~25% of juvenile DM. Prevalence and clinical significance of anti-MJ antibodies in adult Italian PM/DM patients were studied.

METHODS:

Sera from 58 consecutive adult Italian PM/DM patients were analyzed by immunoprecipitation of 35S-labeled K562 cells extract, ELISA (anti-MJ, Jo-1), Western blot and indirect immunofluorescence. Clinical associations were analyzed using information from medical charts.

RESULTS:

Anti-MJ antibodies were the most prevalent specificity (17%) found mainly in DM (30%, 8 cases) vs 8% of PM (2 cases, P = 0.02). Comparing 10 anti-MJ (+) vs 48 anti-MJ (-) cases, DM was more common (P = 0.03), and age at onset was younger in anti-MJ (+) (P = 0.0006). In anti-MJ (+), heliotrope rash (P = 0.01) and calcinosis (P = 0.09) were more frequent. None of them had heart or lung involvement, or malignancy. Myopathy in anti-MJ (+) patients responded well to therapy and none of them had elevated CPK at last visit (0% vs 25% in anti-MJ (-)). Only 60% of anti-MJ (+) showed immunofluorescent nuclear dots staining, despite PML localization of NXP-2/MORC3.

CONCLUSIONS:

Anti-MJ antibodies are the most frequent specificity in our cohort of adult Italian PM/DM. Anti-MJ (+) were associated with young onset DM, calcinosis, no internal organ involvement and good response of myopathy to therapy. Anti-MJ reported in juvenile DM is also found in adult PM/DM, and could be a new useful biomarker.

• Authors: Angela Ceribelli, Micaela Fredi, Mara Taraborelli, Ilaria Cavazzana, Franco Franceschini, Marzia Quinzanini, Angela Tincani, Steven J Ross, Jason Y F Chan, Brad A Pauley, Edward K L Chan, Minoru Satoh
• Journal: Arthritis research & therapy (Arthritis Res Ther) Vol. 14 Issue 2 Pg. R97 (Apr 30 2012) ISSN: 1478-6362 [Electronic] England
• PMID: 22546500 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Autoantibodies
• Biomarkers
• DNA-Binding Proteins
• Adenosine Triphosphatases
• MORC3 protein, human

Topics

• Adenosine Triphosphatases (immunology)
• Adult
• Aged
• Antibody Specificity
• Autoantibodies (biosynthesis)
• Biomarkers (metabolism)
• Cohort Studies
• DNA-Binding Proteins (immunology)
• Dermatomyositis (diagnosis, epidemiology, immunology)
• Female
• Humans
• Italy (epidemiology)
• K562 Cells
• Male
• Middle Aged