Mb. Contri et al., MATRIX PROTEINS WITH HIGH-AFFINITY FOR CALCIUM-IONS ARE ASSOCIATED WITH MINERALIZATION WITHIN THE ELASTIC FIBERS OF PSEUDOXANTHOMA ELASTICUM DERMIS, The American journal of pathology, 148(2), 1996, pp. 569-577
Ultrathin sections from the dermis of five normal subjects and from 10
patients suffering from pseudoxanthoma elasticum (PXE) were analyzed
by immunoelectron microscopy with the aim of identifying and localizin
g proteins associated with the mineral precipitates within the altered
elastic fibers. Serial sections were processed by indirect immunogold
cytochemistry using primary antibodies against human fibronectin, vit
ronectin, bone sialoprotein, alkaline phosphatase, osteonectin, and os
teopontin. In the latter two cases, antibodies against synthetic pepti
des were also used. The results indicate that normal elastic fibers co
ntained osteopontin, and that this protein was associated with the app
arently normal elastin as well as with the needle-shaped mineral preci
pitates in the elastic fibers of patients. On the contrary, significan
t amounts of vitronectin, alkaline phosphatase and, less, of bone sial
oprotein were associated with the polymorphous mineral precipitates in
side the elastic fibers. Large amounts of osteonectin and fibronectin,
together with vitronectin, were localized on the microfilament aggreg
ates, which were often associated with altered elastic fibers in PXE d
ermis and were never visualized in the dermis of control subjects. The
results seem to indicate once more that PXE is a complex disorder of
the fibroblast synthetic control. Elastic fiber mineralization might b
e considered a secondary event, which could depend on the abnormal syn
thesis and accumulation within the elastic fibers of proteins that are
normally involved in mineralization processes.