Lipopolysaccharides are potent inflammatory mediators considered to contribute to destruction of periodontal tissues. Here, we hypothesized that Porphyromonas gingivalis lipopolysaccharide (P-LPS) treatment would regulate gene expression in murine cementoblasts through Toll-like receptor 4. Real-time (RT)-PCR and Northern blot analysis indicated that P-LPS decreased expression of transcripts for osteocalcin (OCN) and receptor activator of nuclear factor κB ligand (RANKL). In contrast, a dose-dependent up-regulation in mRNA levels for osteopontin (OPN) and osteoprotegerin (OPG) was observed. Similarly, ELISA demonstrated decreased RANKL and increased OPG levels. A monoclonal antibody specific for mouse TLR-4/MD-2 partially neutralized the P-LPS effect on cementoblasts. These results indicate that exposure of cementoblasts to P-LPS can alter cell function by regulating markers of osteoclastic activity (e.g., RANKL/OPG), thereby potentially affecting the inflammation-associated resorption of mineralized tissues.
Get full access to this article
View all access options for this article.
References
1.
Akashi S, Shimazu R, Ogata H, Nagai Y, Takeda K, Kimoto M, et al. (2000). Cutting edge: cell surface expression and lipopolysaccharide signaling via the toll-like receptor 4-MD-2 complex on mouse peritoneal macrophages. J Immunol164:3471–3475.
2.
Bainbridge BW, Coats SR, Darveau RP (2002). Porphyromonas gingivalis lipopolysaccharide displays functionally diverse interactions with the innate host defense system. Ann Periodontol7:29–37.
3.
Chiang CY, Kyritsis G, Graves DT, Amar S (1999). Interleukin-1 and tumor necrosis factor activities partially account for calvarial bone resorption induced by local injection of lipopolysaccharide. Infect Immun67:4231–4236.
4.
Choi BK, Lee HJ, Kang JH, Jeong GJ, Min CK, Yoo YJ (2003). Induction of osteoclastogenesis and matrix metalloproteinase expression by the lipooligosaccharide of Treponema denticola. Infect Immun71:226–233.
5.
Coats SR, Reife RA, Bainbridge BW, Pham TT, Darveau RP (2003). Porphyromonas gingivalis lipopolysaccharide antagonizes Escherichia coli lipopolysaccharide at toll-like receptor 4 in human endothelial cells. Infect Immun71:6799–6807.
6.
D’Errico JA, Berry JE, Ouyang H, Strayhorn CL, Windle JJ, Somerman MJ (2000). Employing a transgenic animal model to obtain cementoblasts in vitro. J Periodontol71:63–72.
7.
Darveau RP, Arbabi S, Garcia I, Bainbridge B, Maier RV (2002). Porphyromonas gingivalis lipopolysaccharide is both agonist and antagonist for p38 mitogen-activated protein kinase activation. Infect Immun70:1867–1873.
8.
Denhardt DT, Giachelli CM, Rittling SR (2001). Role of osteopontin in cellular signaling and toxicant injury. Annu Rev Pharmacol Toxicol41:723–749.
9.
Grzesik WJ, Kuzentsov SA, Uzawa K, Mankani M, Robey PG, Yamauchi M (1998). Normal human cementum-derived cells: isolation, clonal expansion, and in vitro and in vivo characterization. J Bone Miner Res13:1547–1554.
10.
Jiang Y, Mehta CK, Hsu TY, Alsulaimani FF (2002). Bacteria induce osteoclastogenesis via an osteoblast-independent pathway. Infect Immun70:3143–3148.
11.
Jin CH, Miyaura C, Ishimi Y, Hong MH, Sato T, Abe E, et al. (1990). Interleukin 1 regulates the expression of osteopontin mRNA by osteoblasts. Mol Cell Endocrinol74:221–228.
12.
Kadono H, Kido J-I, Kataoka M, Yamauchi N, Nagata T (1999). Inhibition of osteoblastic cell differentiation by lipopolysaccharide extract from Porphyromonas gingivalis. Infect Immun67:2841–2846.
13.
Katagiri T, Takahashi N (2002). Regulatory mechanisms of osteoblast and osteoclast differentiation. Oral Dis8:147–159.
14.
Kikuchi T, Matsuguchi T, Tsuboi N, Mitani A, Tanaka S, Matsuoka M, et al. (2001). Gene expression of osteoclast differentiation factor is induced by lipopolysaccharide in mouse osteoblasts via toll-like receptors. J Immunol166:3574–3579.
15.
Kong YY, Yoshida H, Sarosi I, Tan HL, Timms E, Capparelli C, et al. (1999). OPGL is a key regulator of osteoclastogenesis, lymphocyte development and lymph-node organogenesis. Nature397:315–323.
16.
Locklin RM, Khosla S, Turner RT, Riggs BL (2003). Mediators of the biphasic responses of bone to intermittent and continuously administered parathyroid hormone. J Cell Biochem89:180–190.
17.
Loomer PM, Sigush B, Sukhu B, Ellen RP, Tenenbaum HC (1994). Direct effects of metabolic products and sonicated extracts of Porphyromonas gingivalis 2561 on osteogenesis in vitro. Infect Immun62:1289–1297.
18.
Murata T, Ansai T, Takehara T, Kobayashi S, Haneji T (1997). Extracts of Prevotella intermedia and Actinobacillus actinomycetemcomitans inhibit alkaline phosphatase activity in osteoblastic cells in vitro. Oral Dis3:106–112.
19.
Nagai Y, Akashi S, Nagafuku M, Ogata M, Iwakura Y, Akira S, et al. (2002). Essential role of MD-2 in LPS responsiveness and TLR4 distribution. Nat Immunol3:667–672.
20.
Nagasawa T, Kobayashi H, Kiji M, Aramaki M, Mahanonda R, Kojima T, et al. (2002). LPS-stimulated human gingival fibroblasts inhibit the differentiation of monocytes into osteoclasts through the production of osteoprotegerin. Clin Exp Immunol130:338–344.
21.
Nair SP, Meghji S, Wilson M, Reddi K, White P, Henderson B (1996). Bacterially induced bone destruction: mechanisms and misconceptions. Infect Immun64:2371–2380.
22.
Ouyang H, Franceschi RT, McCauley LK, Wang D, Somerman MJ (2000). Parathyroid hormone-related protein down-regulates bone sialoprotein gene expression in cementoblasts: role of the protein kinase A pathway. Endocrinology141:4671–4680.
23.
Poltorak A, He X, Smirnova I, Liu MY, Van Huffel C, Du X, et al. (1998). Defective LPS signaling in C3H/HeJ and C57BL/10ScCr mice: mutations in Tlr4 gene. Science282:2085–2088.
24.
Simonet WS, Lacey DL, Dunstan CR, Kelley M, Chang MS, Luthy R, et al. (1997). Osteoprotegerin: a novel secreted protein involved in the regulation of bone density. Cell89:309–319.
25.
Suda K, Woo JT, Takami M, Sexton PM, Nagai K (2002). Lipopolysaccharide supports survival and fusion of preosteoclasts independent of TNF-alpha, IL-1, and RANKL. J Cell Physiol190:101–108.
26.
Tsukahara Y, Lian Z, Zhang X, Whitney C, Kluger Y, Tuck D, et al. (2003). Gene expression in human neutrophils during activation and priming by bacterial lipopolysaccharide. J Cell Biochem89:848–861.
27.
Yasuda H, Shima N, Nakagawa N, Yamaguchi K, Kinosaki M, Mochizuki S, et al. (1998). Osteoclast differentiation factor is a ligand for osteoprotegerin/osteoclastogenesis-inhibitory factor and is identical to TRANCE/RANKL. Proc Natl Acad Sci USA95:3597–3602.
28.
Zhao M, Xiao G, Berry JE, Franceschi RT, Reddi A, Somerman MJ (2002). Bone morphogenetic protein 2 induces dental follicle cells to differentiate toward a cementoblast/osteoblast phenotype. J Bone Miner Res17:1441–1451.
29.
Zhao M, Berry JE, Somerman MJ (2003). Bone morphogenetic protein-2 inhibits differentiation and mineralization of cementoblasts in vitro. J Dent Res82:23–27.
30.
Zou W, Bar-Shavit Z (2002). Dual modulation of osteoclast differentiation by lipopolysaccharide. J Bone Miner Res17:1211–1218.
