Oral malodorous compound induces osteoclast differentiation without receptor activator of nuclear factor κB ligand.
BACKGROUND
Hydrogen sulfide (H(2)S), the main component of halitosis, is one of the etiologic factors for periodontitis. We recently reported that H(2)S may induce pathologic changes in rat alveolar bone. The objective of this study is to determine the effect of H(2)S on osteoclast differentiation.


METHODS
Murine macrophage cells RAW264 were cultured in medium lacking nuclear factor κB ligand (receptor activator of nuclear factor κB ligand) in 5% CO(2) with air at 37°C for 24 hours; then 0.05, 0.5, or 5 ng/ml H(2)S was added to the CO(2)-air mix for 4 days. The controls received the CO(2)-air mix with no H(2)S. Cell differentiation was evaluated by counting the tartrate-resistant acid-phosphatase (TRAP)-positive cells. Extracellular signaling-regulated kinase1/2 (ERK1/2) and mitogen-activated protein kinase p38 phosphorylation were examined by Western blotting. The bone-resorption activity was determined with the resorption assay of calcium phosphate.


RESULTS
There were significantly more TRAP-positive cells at a concentration of 0.05 ng/ml H(2)S than at the other concentrations (P <0.001). Cathepsin K protein, a specific marker for osteoclasts, was expressed in the H(2)S-induced multinuclear cells. Resorption of calcium phosphate significantly increased in the H(2)S-induced TRAP-positive cells cultured on plates coated with calcium phosphate apatite (P <0.01). The phosphorylation of ERK1/2 and p38 were accelerated by H(2)S, and increased with time. PD98059 and SB203580, specific inhibitors of ERK1/2 and p38, suppressed the activation of these enzymes and osteoclast differentiation by H(2)S.


CONCLUSIONS
Results demonstrate that H(2)S at physiologic concentrations in mouth air induces osteoclasts from RAW264 cells.
Ii
Hisataka
H
Department of Oral Health, Nippon Dental University, Tokyo, Japan.
Imai
Toshio
T
Yaegaki
Ken
K
Irie
Koichiro
K
Ekuni
Daisuke
D
Morita
Manabu
M
D000135:Acid Phosphatase / Q000032:analysis; D000818:Animals; D015153:Blotting, Western; D002130:Calcium Phosphates / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D056657:Cathepsin K / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006209:Halitosis / Q000378:metabolism*; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology; D007527:Isoenzymes / Q000032:analysis; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000032:analysis / Q000037:antagonists & inhibitors; D048052:Mitogen-Activated Protein Kinase 3 / Q000032:analysis / Q000037:antagonists & inhibitors; D010010:Osteoclasts / Q000187:drug effects*; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D053245:RANK Ligand; D000071681:Tartrate-Resistant Acid Phosphatase; D048051:p38 Mitogen-Activated Protein Kinases / Q000032:analysis / Q000037:antagonists & inhibitors
D002130:Calcium Phosphates; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D007527:Isoenzymes; D011725:Pyridines; D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse; C020243:calcium phosphate; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase; D056657:Cathepsin K; C534132:Ctsk protein, mouse; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D006862:Hydrogen Sulfide