Cytokine responses of oral epithelial cells to Porphyromonas gingivalis infection

Accumulating evidence indicates that epithelia are not merely mechanical ba rriers but also important elements of the innate immune system. The present study was performed to examine cytokine responses of oral epithelial cells after infection with the periodontal pathogen Porphyromonas gingivalis. Th e KB-cell line and primary cultures of periodontal pocket epithelium were i nfected with P. gingivalis for assessment of bacterial invasion by an antib iotic protection assay, and examinination of expression of interleukin-l be ta, interleukin-6, interleukin-8, and tumor necrosis factor-alpha by in sit u hybridization and immunohistochemistry. We observed that P. gingivalis in duces a strong cytokine response, positively correlated with the adhesive/i nvasive potential of the infecting strain, in both KB cells and primary cul tures. These findings indicate that the epithelial cells of the periodontal pocket are an integral part of the immune system, eliciting cytokine respo nses to a bacterial challenge. In this context, the adhesive/invasive pheno type of P. gingivalis appears to contribute to pathogenicity.