Oral Epithelial Cell Responses to Multispecies Microbial Biofilms

The oral microbial ecology is comprised of hundreds of bacterial species that co-exist as multispecies biofilms throughout a range of ecological niches in the oral cavity.  However, little is known concerning the interactions of these complex biofilms with host cells. 

Objective: This study used a novel model of multispecies bacterial biofilms to stimulate oral epithelial cells and profile select cytokines and chemokines that contribute to the local inflammatory environment in the periodontium.  

Method: Three multispecies biofilms comprising Streptococcus gordonii/S. oralis/S. sanguinis, Sg/Fusobacterium nucleatum/Porphyromonas gingivalis and Sg/Actinomyces naeslundii/Fn were grown for 3 days on rigid gas permeable contact lens pre-coated with 1% fetal bovine serum.  OKF4 oral epithelial cells were cultured in 48 well plates at 10⁵ cells/well, which were challenged with the biofilms for 24 hrs.  Controls included incubation of the epithelial cells alone or overlaid with contact lens alone.  A profile of cytokines/chemokines I(IL-1α, IL-6, IL-8, TGFα, Gro-1α, IP-10, RANTES, Fractalkine, MCP-1, Mip-1α) were evaluated in supernatants from the epithelial cultures.  

Result: The Sg/So/Ss and Sg/Fn/Pg biofilms elicited significantly elevated levels of IL-1a compared to any of the amounts of planktonic challenge and showed synergistic stimulatory activity compared to that expected as simply an additive effect of the 3 individual bacteria.  Only the Sg/An/Fn multispecies biofilms elicited IL-6 levels above control, although this level was significantly lower than expected from the composite of the monospecies biofilms.  IL-8 was a primary response of the cells to the Sg/An/Fn biofilms, albeit the level to the multispecies biofilm was not enhanced compared to a predicted composite levels from the individual monospecies challenges.  Both the Sg/So/Ss and Sg/Fn/Pg biofilms inhibited the production of IL-8.  

Conclusion: These results represent some of the first data documenting alterations in profiles of oral epithelial cell responses to multispecies biofilms.  Supported by NIH/NIDCR R21-DE018177.