Elevated serum interferon-alpha activity in juvenile dermatomyositis: associations with disease activity at diagnosis and after thirty-six months of therapy.
OBJECTIVE
Interferon-alpha (IFNalpha) has been implicated in the pathogenesis of juvenile dermatomyositis (DM). The aim of this study was to examine serum IFNalpha activity in a cohort of children with juvenile DM to determine relationships between IFNalpha and indicators of disease activity and severity.


METHODS
Thirty-nine children with definite/probable juvenile DM were included in the study. Serum samples were obtained at the time of diagnosis from 18 untreated patients with juvenile DM. Second samples from 11 of these patients were obtained at 24 months, while they were receiving treatment, and third samples were obtained from 7 of these patients at 36 months. The remaining 21 children were studied 36 months after their initial diagnosis. Serum IFNalpha activity was measured using a functional reporter cell assay.


RESULTS
Patients with juvenile DM had higher serum IFNalpha activity than both pediatric and adult healthy control subjects. In untreated patients, serum IFNalpha activity was positively correlated with serum muscle enzyme levels (P<0.05 for creatine kinase, aspartate aminotransferase, and aldolase) and inversely correlated with the duration of untreated disease (P=0.017). The tumor necrosis factor alpha -308A allele was associated with higher serum IFNalpha levels only in untreated patients (P=0.030). At 36 months, serum IFNalpha levels were inversely correlated with muscle enzyme levels in those patients still requiring therapy and with the skin Disease Activity Score in those patients who had completed therapy (P=0.002).


CONCLUSIONS
Serum IFNalpha activity was associated with higher serum levels of muscle-derived enzymes and a shorter duration of untreated disease in patients with newly diagnosed juvenile DM and was inversely correlated with measures of chronic disease activity at 36 months postdiagnosis. These data suggest that IFNalpha could play a role in disease initiation in juvenile DM.
Niewold
Timothy B
TB
University of Chicago Pritzker School of Medicine, Chicago, Illinois 60637, USA. tniewold@medicine.bsd.uchicago.edu
Kariuki
Silvia N
SN
Morgan
Gabrielle A
GA
Shrestha
Sheela
S
Pachman
Lauren M
LM
D000328:Adult; D000483:Alleles; D001219:Aspartate Aminotransferases / Q000378:metabolism; D002675:Child, Preschool; D015331:Cohort Studies; D003402:Creatine Kinase / Q000378:metabolism; D003882:Dermatomyositis / Q000097:blood* / Q000188:drug therapy* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005634:Fructose-Bisphosphate Aldolase / Q000378:metabolism; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D016898:Interferon-alpha / Q000097:blood* / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology; D011110:Polymorphism, Genetic; D012720:Severity of Illness Index; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D007166:Immunosuppressive Agents; D016898:Interferon-alpha; D014409:Tumor Necrosis Factor-alpha; D001219:Aspartate Aminotransferases; D003402:Creatine Kinase; D005634:Fructose-Bisphosphate Aldolase