Underscoring human oral host-pathogen interactions and modulation in an immunocompetent in vitro model of early dysbiosis - PROJECT SUMMARY The human body hosts many distinct, interconnecting microbial populations that exert long-lasting, systemic effects. Due to strong correlations of an imbalanced microbiome and disease prevalence (e.g., periodontitis, arthritis, and Alzheimer’s), studies of host-microbial interactions have increased in importance. In particular, the oral microbiota is well known to have evolved mutualistically with the host, is affected by the distinct architecture of the mouth, and is the primary modulator of oral diseases (e.g., gingivitis and periodontitis). This correlation strongly supports the need to understand the interactions between the oral tissue niche, the oral microbiome, and the host tissue immune response; thus, offering long-term opportunities to identify predictive disease biomarkers and to develop interventional strategies that promote oral and overall health. We have recently reported the development and validation of a 3D oral tissue model based on human primary cells that mimics the native tissue organization and native oxygen gradient within the gingival pocket. These features enabled the long- term culture and characterization of human microbiome with a physiologically relevant level of microbial diversity under healthy and inflammatory conditions (i.e., gingivitis). Gingivitis, the highly prevalent immunoinflammatory precursor to periodontitis, initially presents neutrophils, continuously recruited into the gingival tissue to clear pathogenic microbes. The underlying immune-driven events play a major role in the homeostatic balance between host and microbial communities, providing stability in healthy conditions, while contributing to immune-inflammatory progression in periodontal disease states. Our preliminary data further suggests important immunomodulatory roles for mucin glycans, lipoxins, and resolvins in homeostatic maintenance and the prevention/progression of dysbiosis. However, these observations, to date, have been generated using in vivo animal models, lacking mechanistic nuance that would allow subsequent hypotheses regarding diagnostic/therapeutic roles. Leveraging our team’s expertise in human in vitro modeling, microbiology, mucin biophysics, biogeography, and clinical translation, we aim to leverage a 3D human oral tissue model to provide a mechanistic framework of oral host-microbial interactions and modulation in early dysbiosis to support future therapeutic interventions. Built on our published preliminary data, we propose to: (1) define clinically-relevant profiles of early dysbiosis by monitoring host phenotypic changes as well as cytokine profiles in an immunocompetent OTM compared to clinical gingival tissues; (2) correlate the modulatory role of mucin glycans on the oral microbiome to the host tissue response; (3) deciphering the role of Lipoxin A4 and resolvin E1 on the resolution of inflammatory host response in vitro.
