Aim: To investigate the effect of black-pigmented Bacteroides on the expression of interleukin (IL)-8 gene in human pulp fibroblasts and osteoblasts. Methodology: The supernatants of Porphyromonas endodontalis, P. gingivalis and Prevotella intermedia were used to evaluate IL-8 gene expression in human pulp fibroblasts and osteoblasts. The levels of mRNAs were measured by the quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Results: Investigations of the time-dependence of IL-8 mRNA expression in black-pigmented Bacteroides-treated pulp fibroblasts and osteoblasts revealed a rapid accumulation of the transcript after 2 hofexposure, and remained elevated throughout the 24-h incubation period. In addition, IL-8 mRNA gene expression was also found in human osteoblasts stimulated with black-pigmented Bacteroides. However, black-pigmented Bacteroides was found to be more effective in the induction of IL-8 mRNA gene expression in osteoblasts than in pulp fibroblasts (P < 0.05). Conclusions: Black-pigmented Bacteroides are capable of amplifying the local immune response and promoting pulpal/periapical tissue inflammation by stimulating pulp fibroblasts and osteoblasts to express IL-8. Keywords: black-pigmented Bacteroides, IL-8, osteoblasts, pulp fibroblasts.
