Age-dependent inhibition of ectopic calcification: a possible role for fetuin-A and osteopontin in patients with juvenile dermatomyositis with calcinosis.
OBJECTIVE
To assess if age and/or age-dependent variations in the levels of two major calcification regulatory proteins, fetuin-A and osteopontin, could be associated with an increased risk of calcinosis in children with juvenile dermatomyositis (JDM).


METHODS
The frequency of calcinosis was derived from a national UK database of 212 cases of JDM. Serum fetuin-A and plasma osteopontin levels were determined using ELISA in 15 JDM patients with calcinosis and 15 JDM patients without calcinosis. Healthy controls were 19 age-matched children, 24 adolescents and 13 adults. Sixteen patients with juvenile idiopathic arthritis (JIA) were additional paediatric disease controls.


RESULTS
Of the 212 JDM cases 10% had calcinosis. Calcinosis patients had younger age of disease onset than those without calcinosis (mean age of 5.3 yrs vs 7.1 yrs, respectively, P = 0.016). No significant difference in fetuin-A or osteopontin could be detected between the two JDM groups. Fetuin-A levels in all groups of children and the adolescent group were much lower than described previously in adults, and there was a significant positive correlation between age and fetuin-A level, and also between osteopontin levels in plasma and serum fetuin-A.


CONCLUSIONS
Children who develop JDM at an younger age may have increased risk of developing calcinosis. Physiologically low levels of fetuin-A in young children combined with an additional negative acute-phase effect on fetuin-A due to chronic inflammation could explain in part the propensity to develop ectopic calcification observed in JDM patients, and why calcinosis is less frequent in adults with dermatomyositis.
Marhaug
G
G
Department of Paediatrics, Trondheim University Hospital.
Shah
V
V
Shroff
R
R
Varsani
H
H
Wedderburn
L R
LR
Pilkington
C A
CA
Brogan
P A
PA
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000375:Aging / Q000097:blood; D001798:Blood Proteins / Q000032:analysis / Q000502:physiology*; D002114:Calcinosis / Q000097:blood / Q000209:etiology*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003882:Dermatomyositis / Q000097:blood / Q000150:complications* / Q000188:drug therapy; D006801:Humans; D053495:Osteopontin / Q000097:blood / Q000502:physiology*; D012307:Risk Factors; D060749:alpha-2-HS-Glycoprotein
C556354:AHSG protein, human; D001798:Blood Proteins; D060749:alpha-2-HS-Glycoprotein; D053495:Osteopontin