Anaerobic microbiota facilitate pathogen access to the airway epithelium in a novel co-culture model of colonization

ABSTRACT Chronic rhinosinusitis (CRS) is a prevalent condition characterized by mucus stasis, persistent inflammation, and infection of the paranasal sinuses. It often involves the bacterium Pseudomonas aeruginosa, especially in individuals with cystic fibrosis or a history of antibiotic use. While P. aeruginosa is a known opportunistic pathogen that employs a diverse array of virulence factors to cause airway infections, its ability to thrive in the sinonasal environment is also likely influenced by its local microbial ecology. For instance, anaerobic bacterial genera, such as Streptococcus, Veillonella, and Prevotella, are also commonly found in CRS and may contribute to P. aeruginosa persistence. Here we sought to test the hypothesis that anaerobes promote P. aeruginosa colonization of the upper airways, specifically through degradation of mucin glycoproteins that decorate the epithelial surface. Using a novel dual oxic-anoxic culture platform termed DOAC, we co-cultured Calu-3 epithelial cells with a CRS-derived anaerobic microbial community. We observed increased expression of inflammatory marker genes and degradation of mucin glycoproteins, along with enhanced P. aeruginosa colonization of the epithelial surface after anaerobe pre-treatment. Furthermore, mucins isolated from anaerobe-treated Calu-3 cells promoted greater P. aeruginosa attachment to microtiter plates in vitro compared to intact mucins. These results suggest that anaerobic microbiota may shape the sinonasal environment in a way that favors P. aeruginosa persistence, offering new insights into CRS pathogenesis and potential therapeutic targets to disrupt detrimental bacterial interactions in chronic airway disease. IMPORTANCE The prevalence and abundance of strict and facultative anaerobic bacteria in chronic sinusitis as detected by culture-independent sequencing has renewed interest in their potential role(s) in disease onset, progression, and treatment. However, reductionist study of interactions between anaerobic microbiota and the host has been limited by the lack of laboratory models compatible with their conflicting oxygen demands. The significance of this work lies in the use of a novel co-culture platform, termed DOAC, to interrogate anaerobe interactions with the airway epithelium. We use this platform to show that anaerobic CRS microbiota elicit a pro-inflammatory response, degrade mucin glycoproteins, and promote mucosal colonization by the canonical CRS pathogen, Pseudomonas aeruginosa. This work highlights highlight a potential role of anaerobic microbiota in conditioning the sinonasal environment to favor pathogen colonization. Competing Interest Statement The authors have declared no competing interest.