TY - JOUR
T1 - Family 2 cystatins inhibit osteoclast-mediated bone resorption in calvarial bone explants
AU - Brand, H.S.
AU - Lerner, U.H.
AU - Grubb, A.
AU - Beertsen, W.
AU - van Nieuw Amerongen, A.
AU - Everts, V.
N1 - ACTA
PY - 2004
Y1 - 2004
N2 - Osteoclastic bone resorption depends on the activity of various proteolytic enzymes, in particular those belonging to the group of cysteine proteinases. Biochemical studies have shown that cystatins, naturally occurring inhibitors of these enzymes, inhibit bone matrix degradation. Since the mechanism by which cystatins exert this inhibitory effect is not completely resolved yet, we studied the effect of cystatins on bone resorption microscopically and by Ca-release measurements. Calvarial bone explants were cultured in the presence or absence of family 2 cystatins and processed for light and electron microscopic analysis, and the culture media were analyzed for calcium release. Both egg white cystatin and human cystatin C decreased calcium release into the medium significantly. Microscopic analyses of the bone explants demonstrated that in the presence of either inhibitor, a high percentage of osteoclasts was associated with demineralized non-degraded bone matrix. Following a 24-h incubation in the presence of cystatin C, 41% of the cells were adjacent to areas of demineralized non-degraded bone matrix, whereas in controls, this was only 6%. If bone explants were cultured with both PTH and cystatin C, 60% of the osteoclasts were associated with demineralized non-degraded bone matrix, compared to 27% for bones treated with PTH only (P < 0.01). Our study provides evidence that cystatins, the naturally occurring inhibitors of cysteine proteinases, reversibly inhibit bone matrix degradation in the resorption lacunae adjacent to osteoclasts. These findings suggest the involvement of cystatins in the modulation of osteoclastic bone degradation
AB - Osteoclastic bone resorption depends on the activity of various proteolytic enzymes, in particular those belonging to the group of cysteine proteinases. Biochemical studies have shown that cystatins, naturally occurring inhibitors of these enzymes, inhibit bone matrix degradation. Since the mechanism by which cystatins exert this inhibitory effect is not completely resolved yet, we studied the effect of cystatins on bone resorption microscopically and by Ca-release measurements. Calvarial bone explants were cultured in the presence or absence of family 2 cystatins and processed for light and electron microscopic analysis, and the culture media were analyzed for calcium release. Both egg white cystatin and human cystatin C decreased calcium release into the medium significantly. Microscopic analyses of the bone explants demonstrated that in the presence of either inhibitor, a high percentage of osteoclasts was associated with demineralized non-degraded bone matrix. Following a 24-h incubation in the presence of cystatin C, 41% of the cells were adjacent to areas of demineralized non-degraded bone matrix, whereas in controls, this was only 6%. If bone explants were cultured with both PTH and cystatin C, 60% of the osteoclasts were associated with demineralized non-degraded bone matrix, compared to 27% for bones treated with PTH only (P < 0.01). Our study provides evidence that cystatins, the naturally occurring inhibitors of cysteine proteinases, reversibly inhibit bone matrix degradation in the resorption lacunae adjacent to osteoclasts. These findings suggest the involvement of cystatins in the modulation of osteoclastic bone degradation
KW - AMC wi-buiten
U2 - https://doi.org/10.1016/j.bone.2004.05.015
DO - https://doi.org/10.1016/j.bone.2004.05.015
M3 - Article
C2 - 15336605
SN - 8756-3282
VL - 35
SP - 689
EP - 696
JO - Bone
JF - Bone
IS - 3
ER -