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Figure 2. Effect of P. gingivalis lipopolysaccharide (P-LPS) on gene expression: (A) Cementoblasts (OCCM-30) were cultured in DMEM (5% FBS) with ascorbic acid (AA) (50 µg/mL) (control - CN) or plus P-LPS (1–1000 ng/mL). mRNA was extracted after 24 hrs, and expression of bone sialoprotein (BSP), osteocalcin (OCN), collagen I (Col I), and osteopontin (OPN) was analyzed by Northern blot. Results from two separate experiments (n = 2) showed that P-LPS regulates expression of mineral-associated genes in a dose-dependent manner, with a marked decrease in OCN and an increase in OPN and Col I transcripts. Effect of P-LPS on genes/proteins associated with bone resorption: (B) Cementoblasts (OCCM-30) were cultured as described above (n = 2). RNA was extracted after 24 hrs and analyzed by real-time PCR, and values were normalized to GAPDH and calibrator values. P-LPS significantly decreased RANKL and increased OPG expression in a dose-dependent manner. (C) Protein levels evaluated by ELISA. Cell lysate and medium were used to obtain RANKL and OPG levels, respectively. Note that the impact of P-LPS on protein levels parallels findings on gene expression. Bars represent mean ± SD from two separate experiments, with similar results (n = 2). *P < 0.001 and **P < 0.05 vs. control.
