Adhesion of Porphyromonas gingivalis fimbriae to human gingival cell line Ca9-22

In this study, we examined the effects of selected environmental factors on the adhesion of Porphyromonas gingivalis fimbriae, an important structure involved in attachment of the bacteria to human gingival cells. The human gingival carcinoma cell line Ca9-22 was grown in microculture plates, and adherence was detected by use of I-125-labeled fimbriae. Adhesion was increased by changes in pH from 7.0-8.0, but was decreased by increase in the sodium chloride concentration above 0.15 M. Trypsin treatment of Ca9-22 cells also augmented adhesion of the fimbriae to the cells. These results indicate that fimbrial adhesion to gingival cells is controlled by various environmental factors, and the data on trypsin treatment suggest that elevated levels of protease in the gingival sulcus, such as can occur with poor oral hygiene and gingivitis, may expose adhesion molecules on the gingival cell surface, thereby promoting the attachment of P. gingivalis fimbriae.