Open AccessJuvenile dermatomyositis calcifications selectively displayed markers of bone formation
Author(s) -
Urganus Annette L.,
Zhao Yongdong,
Pachman Lauren M.
Publication year - 2009
Publication title -
arthritis care & research
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/art.24391
Subject(s) - osteopontin , bone sialoprotein , osteoid , connective tissue , pathology , chemistry , osteocalcin , juvenile dermatomyositis , calcification , tartrate resistant acid phosphatase , alkaline phosphatase , endocrinology , biology , medicine , osteoclast , dermatomyositis , biochemistry , enzyme , in vitro
Abstract Objective To determine the presence of small integrin‐binding ligand N ‐linked glycoprotein (SIBLING) and bone components in juvenile dermatomyositis (DM) pathologic calcifications. Methods Calcifications were removed from 4 girls with juvenile DM symptoms for mean ± SD 36.9 ± 48.3 months and were stained for SIBLING proteins: full‐length osteopontin (OPN), bone sialoprotein (BSP), dentin matrix protein 1 (DMP1), dentin phosphoprotein (DPP), and matrix extracellular phosphoglycoprotein (MEPE); bone markers: osteocalcin (OC), core‐binding factor α 1 (CBFα1), and alkaline phosphatase (AP) for osteoblasts; tartrate‐resistant acid phosphatase (TRAP) for osteoclasts; and the mineral regulators osteonectin (ON) and matrix Gla protein (MGP). The deposit center, periphery, adjacent connective tissue, and vascular endothelial cells were examined. Results Alizarin red stained calcified deposits that did not localize with collagen, like bone, under polarized light. Hematoxylin and eosin stain revealed a paucity of connective tissue and absence of bone‐like structures. The deposits, connective tissue, and vascular endothelial cells were positive for BSP, DPP, DMP1, and AP; MEPE was not detected. OC, ON, and MGP were present in the deposits and vascular endothelial cells; OPN and CBFα1 were present in deposits and connective tissue. TRAP‐positive osteoclasts were localized to the calcification periphery. Conclusion The disorganized juvenile DM calcifications differ in structure, composition, and protein content from bone, suggesting that they may not form through an osteogenic pathway. Osteoclasts at the deposit surface represent an attempt to initiate its resolution.