Regulation of Cementoblast Function by P. gingivalis Lipopolysaccharide via TLR2

Although cementoblasts express Toll-like receptors (TLR)-2 and -4, little is known regarding the possible participation of cementoblasts in the inflammatory response. We investigated the effects of Porphyromonas gingivalis lipopolysaccharide (LPS), tetra- and penta-acylated lipid A species (designated PgLPS1435/1449 and PgLPS1690, respectively), on gene expression of osteoclastogenesis-associated molecules in murine cementoblasts. Real-time quantitative RT-PCR analysis revealed that receptor activator of NF-κB ligand (RANKL), interleukin-6, Regulated on activation, normal T-cell expressed, and secreted (RANTES), macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1 were rapidly and dramatically induced upon stimulation with PgLPS1690, but only slightly induced with PgLPS1435/1449. Osteoprotegerin, which was expressed constitutively, was not altered significantly. ELISA demonstrated synthesis of corresponding proteins. PgLPS1690 significantly induced transcripts for NF-κB, and this activation was inhibited by pre-treatment with anti-TLR-2 but not with TLR-4 antibodies. These results suggest that cementoblasts participate in the recruitment of osteoclastic precursor cells by up-regulation of chemokines/cytokines.