The otic microbiome and its role in middle ear decompression and barotrauma prevention
Abstract
The proposed research seeks to expand our existing ONR award (#N00014-17-2678) to investigate the ecophysiology and prophylactic potential of the otic microbiome in warfighters. The new award would capitalize on non-invasive protocols we designed to collect otic, oropharyngeal and buccal samples from healthy young adults and sequence the microbiomes (16S rRNA-V4). Our initial survey identified a diverse otic bacterial community with many oropharyngeal and buccal keystone taxa and with most of the functional traits predicted for the microbiomes of the neighboring oral regions. We applied neutral models to predict the contribution of oral dispersal to the composition of the otic microbiome and unmask responses to positive selection. Taxonomic analyses of the otic microbiomes demonst. By including a cohort of recreational divers, we identified aeration frequency as a major selective force in strain selection Thus, the otic communities of divers had less anaerobic OTUs and a higher representation of Streptococcus, an abundant oral taxon that sustains syntrophic consortia critical for mucosal nutrition and health. Further, the otic streptococcal isolates were phylogenetically distinct and could be enriched under anaerobiosis and hydrostatic pressure relevant to the middle ear. The isolates also had antimicrobial activity against common otopathogens and high recolonization potential. These physiological attributes make them attractive probiotic strains for reintroduction as nasal aerosols and prophylactic treatment of pressure-induced otic trauma. The finding that aeration and oral dispersal determines the assembly of the otic communities is particularly relevant to the warfighters physiology. Nutrition, which is critical to warfighter performance, triggers host responses (inflammation, blood flow, etc.) that affect the cycles of aperture of the tympanic tube. Nutrition also controls the membership of the oral communities and, by extent, the otic microbiome and functionality. Pulmonary rate also influences aerial dispersal and microbial immigration in the middle ear. Moreover, tubal aperture slows down during sleep and is, therefore, responsive to sleep deprivation. These examples underscore the importance of host-microbial interactions in otic homeostasis and, more broadly, warfighter wellness, resilience and military performance. Hence, we propose to expand our project to sequence the otic microbiome of military divers participating in the Bioenergetics study conducted by our colleagues at the Navy Experimental Diving Unit (NEDU). The work is planned in two phases: Phase 1 (pilot study): 8-month phase to conduct a 16S-V4 pilot survey (20 NEDU divers and 20 non-divers at Michigan State) and establish relevance to the Navy.Phase 2 (option): 12-month phase to expand the surveys size to refine the analyses, improve the predictive value of the models, and enable independent analyses of combat divers, mechanical divers and diving school students. This phase will also include targeted cultivation of otic taxa with highest prophylactic potential during Navy operations. PI Reguera will lead the efforts of a team comprised of three additional members: co-PI Kashefi, a graduate student, and an undergraduate student helper. Findings from our study will provide novel insights into host-interactions critical for otic homeostasis and warfighter resilience. Inll provide understand on the dynamic response of otic biomarkers on host variables (nutrition, metabolism and respiration) directlyl replacement therapies for the manipulation of the otic microbial community and the functionality of the middle ear under stress.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 08, 2020
- Source ID
- N000142012471
Entities
People
- Gemma Reguera
Organizations
- Michigan State University
- Office of Naval Research
- United States Navy