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Gutta-percha-stimulated mouse macrophages release factors that activate the bone resorptive system of mouse calvarial
U Sjögren1, A Ohlin, G Sundqvist
1Department of Endodontics, Umeå University, Sweden. Ulf.Sjogren@endo.umu.se
Abstract:
This study investigated the capacity of macrophages exposed to gutta-percha particles to produce factors affecting bone metabolism. Peritoneal mouse macrophages were isolated and incubated with and without gutta-percha particles, and the supernatants were assessed for bone resorbing activity by adding macrophage-conditioned media to cultures of neonatal mouse calvarial bones. Bone resorption was measured by mineral mobilization (45Ca release) and matrix degradation (3H from [3H]proline labelled bones). The results showed that supernatant from gutta-percha-stimulated macrophages enhanced bone resorption. This effect was related to the amount of gutta-percha, and the concentration and time of exposure to the conditioned media. Stimulated macrophages released enhanced amounts of prostaglandins E2 and I2; however, indomethacin, which inhibits the prostanoid response, had no effect on bone resorbing activity. The stimulatory effect on bone resorption was inhibited by calcitonin, interleukin-1 receptor antagonistic protein, and by antiserum neutralizing mouse interleukin-1alpha(IL-1alpha), but not by anti-IL-1beta. Filtration experiments revealed that the molecules involved in the resorption activity had an apparent molecular weight between 3000 and 30,000 Da. These experiments show that mouse peritoneal macrophages, when exposed to gutta-percha particles, release factors which have a bone resorbing activity that is primarily due to enhanced production of IL-1alpha.
Insights
Macrophages exposed to gutta-percha particles release factors that stimulate bone resorption. Interleukin-1alpha (IL-1alpha) is identified as the primary mediator of this bone-resorbing activity.
Area of Science:
- Immunology
- Bone Biology
- Biomaterials Science
Background:
- Gutta-percha is a common root canal filling material.
- Macrophages play a crucial role in bone remodeling and inflammation.
- The interaction between biomaterials and immune cells can influence bone metabolism.
Purpose of the Study:
- To investigate the effect of gutta-percha particles on macrophage-derived factors involved in bone metabolism.
- To identify the specific factors produced by macrophages that affect bone resorption.
- To elucidate the mechanism by which gutta-percha influences bone resorption.
Main Methods:
- Isolation and incubation of mouse peritoneal macrophages with gutta-percha particles.
- Assessment of bone resorbing activity in macrophage-conditioned media using neonatal mouse calvarial bone cultures.
- Measurement of mineral mobilization (45Ca release) and matrix degradation (3H-proline release).
- Analysis of prostaglandin E2 and I2 production.
- Inhibition studies using indomethacin, calcitonin, IL-1 receptor antagonist, and anti-IL-1alpha/IL-1beta antiserum.
- Molecular weight determination of active factors via filtration.
Main Results:
- Supernatants from gutta-percha-stimulated macrophages significantly enhanced bone resorption.
- Bone resorption was dose- and time-dependent on gutta-percha exposure and conditioned media.
- Stimulated macrophages showed increased production of prostaglandins E2 and I2, but prostaglandin inhibition did not affect bone resorption.
- Bone resorption was inhibited by calcitonin, IL-1 receptor antagonist, and anti-IL-1alpha antiserum, but not anti-IL-1beta.
- Active factors involved in resorption had a molecular weight between 3000 and 30,000 Da.
Conclusions:
- Mouse peritoneal macrophages exposed to gutta-percha particles release bone-resorbing factors.
- The primary factor responsible for the enhanced bone resorption is interleukin-1alpha (IL-1alpha).
- These findings suggest a potential mechanism for periapical bone loss associated with gutta-percha use in endodontics.