Emulating the gingival-tooth interface during bacterial, fungal, and viral infection in a microphysiological model of the human oral cavity

The anatomical complexity and distinctive tissue environment of the human oral cavity pose major challenges to modeling oral infection and host-microbe interactions in preclinical laboratory settings. Here we present a bioengineered oral microphysiological system comprising vascularized human gingival tissue integrated with tooth analogs that together recreate a functional unit of the human oral cavity. We incorporated Streptococcus mutans and Candida albicans into this system to model cross-kingdom biofilm formation, microbial dissemination, and host-microbial interactions at the gingival-tooth interface. Single-cell RNA sequencing and global metabolomics analysis revealed that fungal colonization induces epithelial-to-mesenchymal transition associated with distinct transcriptional and metabolic signatures. Our platform also allowed us to simulate SARS-CoV-2 infection and examine gingival responses to live-virus challenge. Finally, we integrated the engineered gingival tissue with controlled human saliva flow to show that hyposalivation potentiates the pathogenic capacity of fungal infection. This work demonstrates the potential of oral microphysiological systems as an experimental platform for in vitro modeling and mechanistic investigation of host-microbe interactions under controlled, human-relevant conditions.