Nitric oxide promotes infectious bone resorption by enhancing cytokine-stimulated interstitial collagenase synthesis in osteoblasts.
This experiment was undertaken to determine the role of macrophage-derived nitric oxide (NO) in mediating lipopolysaccharide (LPS)-induced bone resorption by using an in vitro co-culture system and an in vivo model of infectious bone resorption. Our results demonstrated that LPS stimulated the expression of inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF)-a mRNAs and nitrite synthesis in the J774 mouse macrophage cell line but not in the UMR-106 (rat) and MC3T3-E1 (mouse) osteoblast cell lines. Conditioned media (CM) from LPS-stimulated J774 triggered only low to moderate levels of iNOS mRNAs in MC3T3-E1 and a trivial effect in UMR-106. On the other hand, CM induced matrix metalloproteinase-1 (MMP-1) gene expression in both osteoblast cell lines. The NOS inhibitor N(G)-monomethyl-L-arginine (L-NMMA) did not alter this effect in MC3T3-E1 and UMR-106, whereas TNF-a antibody diminished the CM-induced MMP-1 gene expression in both cell lines. Interestingly, SNAP, a NO donor, although by itself is not a MMP-1 stimulator for UMR-106, augmented the TNF-alpha-stimulated MMP-1 mRNA production in UMR-106. In a J774/UMR-106 co-culture system, LPS stimulated significant MMP-1 gene expression in UMR-106, and this upregulation was abolished by L-NMMA and TNF-alpha antibodies. Immunohistochemical analysis in a rat model of infectious bone resorption (periapical lesion) showed co-distributions of iNOS+ macrophages and MMP-1+ osteoblasts around the osteolytic areas. Administration of L-NMMA markedly reduced the extent of bone loss and the percentage of MMP-1-synthesizing osteoblasts. These data suggest that NO derived from macrophages after LPS stimulation may enhance bone loss by augmenting the cytokine-induced MMP-1 production in osteoblasts.
Lin
Sze-Kwan
SK
Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan.
Kok
Sang-Heng
SH
Kuo
Mark Yen-Ping
MY
Lee
Ming-Shu
MS
Wang
Chih-Chiang
CC
Lan
Wan-Hong
WH
Hsiao
Michael
M
Goldring
Steven R
SR
Hong
Chi-Yuan
CY
D016475:3T3 Cells; D000818:Animals; D001862:Bone Resorption / Q000209:etiology* / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D018920:Coculture Techniques; D017077:Culture Media, Conditioned; D015870:Gene Expression; D007239:Infections / Q000209:etiology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity; D008264:Macrophages / Q000378:metabolism; D020781:Matrix Metalloproteinase 1 / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D019323:omega-N-Methylarginine / Q000494:pharmacology
D017077:Culture Media, Conditioned; D008070:Lipopolysaccharides; D020030:Nitric Oxide Donors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C496318:Nos2 protein, rat; D020781:Matrix Metalloproteinase 1