In vitro 3D human gingival tissue model to study oral microbiome

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PROJECT SUMMARY The oral cavity contains different microenvironments, i.e. the non-shedding surface of the teeth and the epithelial mucosa, where oral barriers and microbial communities coexist. The interactions and balances between these two communities are responsible for oral tissue homeostasis or dysbiosis, that ultimately dictate health or disease. Disruption of this equilibrium is the first necessary step towards chronic inflammation and permanent tissue damage in the case of chronic periodontitis. Current experimental animal and in vitro models do not fully resemble the human condition. To improve clinical outcomes and design effective treatments, new humanized experimental tools are needed to further elucidate these initial host-pathogens unbalances. Previously developed in vitro systems have been used to test irritant responses of new dental materials, dentifrices, and oral care consumer products, but are unable to maintain the complexity of the oral pathogen community organization, due to the lack of the native oxygen and metabolic conditions. In addition, host saliva contributes to the maintenance of the overall oral system stability by buffering the oral environment, providing nutrition to the different communities and delivering antimicrobial features. Therefore, the recapitulation of physiological oral conditions, including oxygen gradients, physiological shear stress, and buffering from saliva will enhance the functions of a humanized sustained gingival tissue model to study initial host-pathogen interactions in vitro. We are proposing to design a physiological culture system based on artificial saliva in order to support long-term culture after inoculation with oral microbiota derived from healthy patients. We will replicate the stability of the ecosystem and evaluate the contribution of host saliva to buffer and provide nutrition to the oral community, as well as physiological shear stress that contributes to the maturation and maintenance of a healthy epithelium. The 3D anatomical gingival tissue model has been shown to modulate the production of a range of cytokines and chemokines in response to interactions with inoculated plaque samples from healthy patients. To assess the clinical relevance of this response, we will study the production of selected cytokines under different conditions; response to the addition of plaque derived from healthy and diseased (gingivitis) patients in comparison to crevicular fluid extracted from the same pool of patients. The efforts will elucidate the initial interactions and balances between these two communities that are responsible for the oral tissue homeostasis or dysbiosis, that ultimately dictates healthy or diseased tissue states. The interdisciplinary team involved in the project has established collaborative activities and includes material scientists, tissue engineers, microbiologists, and periodontists. They are experts in host-material interactions, advanced in vitro tissue and culture models, microbial pathogenesis, host defense, periodontal immunology, and periodontal inflammation.