title: Anti-MJ/NXP-2 autoantibody specificity in a cohort of adult Italian patients with polymyositis/dermatomyositis.
abstract: BACKGROUND
  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.affiliation: Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610-0424, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Ceribelli
authors.forename: Micaela
authors.initials: M
authors.lastname: Fredi
authors.forename: Mara
authors.initials: M
authors.lastname: Taraborelli
authors.forename: Ilaria
authors.initials: I
authors.lastname: Cavazzana
authors.forename: Franco
authors.initials: F
authors.lastname: Franceschini
authors.forename: Marzia
authors.initials: M
authors.lastname: Quinzanini
authors.forename: Angela
authors.initials: A
authors.lastname: Tincani
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Ross
authors.forename: Jason Y F
authors.initials: JY
authors.lastname: Chan
authors.forename: Brad A
authors.initials: BA
authors.lastname: Pauley
authors.forename: Edward K L
authors.initials: EK
authors.lastname: Chan
authors.forename: Minoru
authors.initials: M
authors.lastname: Satoh
mesh_terms: D000251:Adenosine Triphosphatases / Q000276:immunology*; D000328:Adult; D000368:Aged; D000918:Antibody Specificity; D001323:Autoantibodies / Q000096:biosynthesis*; D015415:Biomarkers / Q000378:metabolism; D015331:Cohort Studies; D004268:DNA-Binding Proteins / Q000276:immunology*; D003882:Dermatomyositis / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology*; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D020014:K562 Cells; D008297:Male; D008875:Middle Aged
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D004268:DNA-Binding Proteins; D000251:Adenosine Triphosphatases; C551732:MORC3 protein, human