Alendronate regulates cytokine production induced by lipid A through nuclear factor-κB and Smad3 activation in human gingival fibroblasts.
OBJECTIVE
Nitrogen-containing bisphosphonates (NBPs) are widely used as anti-bone-resorptive drugs. However, use of NBPs results in inflammatory side-effects, including jaw osteomyelitis. In the present study, we examined the effects of alendronate, a typical NBP, on cytokine production by human peripheral blood mononuclear cells (PBMCs) and gingival fibroblasts incubated with lipid A.


METHODS
The PBMCs and gingival fibroblasts were pretreated with or without alendronate for 24 h. Cells were then incubated in the presence or absence of lipid A for a further 24 h. Levels of secreted human interleukin (IL)-1β, IL-6, IL-8 and monocyte chemoattractant protein-1 (MCP-1) in culture supernatants were measured by ELISA. We also examined nuclear factor-κB (NF-κB) activation in both types of cells by ELISA. Activation of Smad3 in the cells was assessed by flow cytometry. In addition, we performed an inhibition assay using SIS3, a specific inhibitor for Smad3.


RESULTS
Pretreatment of PBMCs with alendronate promoted lipid A-induced production of IL-1β and IL-6, but decreased lipid A-induced IL-8 and MCP-1 production. In human gingival fibroblasts, alendronate pretreatment increased lipid A-induced production of IL-6 and IL-8, and increased NF-κB activation in gingival fibroblasts but not PBMCs stimulated with lipid A. In contrast, alendronate activated Smad3 in both types of cells. Finally, SIS3 inhibited alendronate-augmented IL-6 and IL-8 production by human gingival fibroblasts but up-regulated alendronate-decreased IL-8 production by PBMCs.


CONCLUSIONS
These results suggest that alendronate-mediated changes in cytokine production by gingival fibroblasts occur via regulation of NF-κB and Smad3 activity.
Tamai
R
R
Department of Oral Medical Science, Ohu University School of Dentistry, 31-1 Misumido, Tomitamachi, Koriyama, Fukushima, Japan.
Sugiyama
A
A
Kiyoura
Y
Y
D019386:Alendronate / Q000494:pharmacology*; D000704:Analysis of Variance; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis / Q000235:genetics; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D005786:Gene Expression Regulation; D005881:Gingiva / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000235:genetics; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008050:Lipid A / Q000276:immunology; D016328:NF-kappa B / Q000378:metabolism*; D051900:Smad3 Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects*
D050071:Bone Density Conservation Agents; D018932:Chemokine CCL2; D016207:Cytokines; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D008050:Lipid A; D016328:NF-kappa B; D051900:Smad3 Protein; D019386:Alendronate