Effects of Oral Commensal Streptococci on Invasion into Oral Epithelial Cells.

The objective of this study was to determine if the interaction between common oral commensal bacteria and oral epithelial cells would provide protective effects against the invasion of periodontopathogen . Oral epithelial OKF6/Tert cells were used in co-cultures with , , , and . The viability of OKF6/Tert cells following a bacterial challenge was evaluated by trypan blue exclusion. The adherence of commensal species was determined by CFU counts. invasion in OKF6/Tert cells was assessed before and after exposure to commensal species according to CFU counts. Viability assays show that only and display low toxicity toward OKF6/Tert cells. Both commensals adhere to OKF6/Tert cells at an average ratio of 1 CFU to 10 cells. invasion into host cells is significantly reduced by 25% or 60% after exposure to or , respectively. The results suggest that these commensal species bind to host cells and diminish invasion. This is important in the context of periodontal disease since primarily acts on the host by invading it. Therefore, efforts to decrease invasion will eventually lead to future therapies harnessing the mechanisms employed by oral commensal bacteria.