The exact causative factor(s) of bone erosion in cholesteatoma are not
known. In recent pears, the possible role of cytokines has drawn atte
ntion. Since the studies on cytokines in cholesteatoma are limited and
depend on histopathological methods, the present work approached this
subject by biochemical determination of TNF-alpha lysosomal enzymes,
acid phosphatase (total and tartrate resistant), cathepsin B, leucyl a
minopeptidase lysozyme together with non-lysosomal enzymes calpain I a
nd II in 50 cholesteatoma samples (epithelial and subepithelial tissue
s) in comparison with 14 normal skin samples from the external ear can
al. The study revealed significantly increased levels of all previous
indices in cholesteatoma epithelium and subepithelial tissues compared
with healthy skin. The levels of these indices reflected the clinical
severity of the disease as reflected by their significant increase in
cases with erosion of two or three ossicles, erosion of dural plate,
sinus plate and facial canal and more extensive cholesteatoma. It is l
ikely that TNF-alpha acts both directly by causing bone erosion and in
directly by stimulating the release of lysosomal enzymes. The latter m
echanism is supported by the significant correlations observed between
TNF-alpha. and lysosomal enzymes. The non-lysosomal enzymes calpain I
and II seem to participate in the bone erosion associated with choles
teatoma by their involvement in collagen destruction. Due to the sugge
sted role of TNF-alpha in bone destruction associated with cholesteato
ma the use of anti-inflammatory drugs should be taken into considerati
on in otitis media to diminish bone destruction. Similarly, antibiotic
s should be used to prevent the deleterious effects of bacterial endot
oxin.