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Inhibition of stimulated bone resorption in vitro by TIMP-1 and TIMP-2
P A Hill1, J J Reynolds, M C Meikle
1Cell and Molecular Biology Department, Strangeways Research Laboratory, Cambridge UK.
Abstract:
Recombinant human TIMP-1 and TIMP-2 (tissue inhibitors of metalloproteinases) inhibited bone resorption induced by either parathyroid hormone or 1,25-dihydroxyvitamin D3 in cultured neonatal mouse calvariae. The inhibition was reversible, dose-dependent and complete at 1 microgram/ml inhibitor concentration. TIMP-2 was more potent than TIMP-1. TIMP-1 and TIMP-2 also inhibited basal bone resorption. Neither metalloproteinase inhibitor affected protein synthesis, DNA synthesis, the PTH-enhanced secretion of beta-glucuronidase or the spontaneous release of lactate dehydrogenase. These results suggest that endogenous TIMPs play a central role in regulating both physiological and pathological bone resorption.
Insights
Tissue inhibitors of metalloproteinases (TIMPs) like TIMP-1 and TIMP-2 effectively reduce bone resorption. These findings highlight the crucial role of endogenous TIMPs in regulating bone metabolism.
Area of Science:
- Biochemistry
- Cell Biology
- Orthopedics
Background:
- Bone resorption is a critical process in skeletal remodeling and disease.
- Metalloproteinases play a role in bone resorption, and their activity is regulated by inhibitors.
- Tissue inhibitors of metalloproteinases (TIMPs) are endogenous regulators of matrix metalloproteinases.
Purpose of the Study:
- To investigate the effect of recombinant human TIMP-1 and TIMP-2 on bone resorption in vitro.
- To determine the potency and characteristics of TIMP-mediated inhibition of bone resorption.
Main Methods:
- Cultured neonatal mouse calvariae were used as an in vitro model system.
- Bone resorption was induced by parathyroid hormone (PTH) or 1,25-dihydroxyvitamin D3.
- Recombinant human TIMP-1 and TIMP-2 were added at varying concentrations.
Main Results:
- Both TIMP-1 and TIMP-2 significantly inhibited PTH- and vitamin D3-induced bone resorption.
- Inhibition was reversible, dose-dependent, and complete at 1 µg/ml.
- TIMP-2 demonstrated greater potency than TIMP-1.
- TIMPs also inhibited basal bone resorption without affecting cellular synthesis or enzyme release.
Conclusions:
- Endogenous TIMPs are key regulators of both physiological and pathological bone resorption.
- TIMP-1 and TIMP-2 represent potential therapeutic agents for conditions involving excessive bone resorption.