# Anaerobic microbiota promote pathogen association with the airway epithelium

## TL;DR

This study shows that anaerobic bacteria in the nasal passages help a harmful bacterium, Pseudomonas aeruginosa, stick to airway cells by breaking down protective mucus.

## Contribution

The study demonstrates that anaerobic microbiota enhance P. aeruginosa colonization by degrading mucin glycoproteins.

## Key findings

- Anaerobe exposure increased epithelial inflammation and degraded mucin glycoproteins.
- Anaerobe pre-treatment significantly enhanced P. aeruginosa attachment to epithelial cells.
- Mucins from anaerobe-treated cells promoted more P. aeruginosa attachment in vitro.

## Abstract

Introduction. Chronic rhinosinusitis (CRS) is a prevalent condition characterized by mucus stasis, persistent inflammation and infection of the paranasal sinuses. CRS often involves infection by the bacterium Pseudomonas aeruginosa, especially in individuals with cystic fibrosis or a history of antibiotic use. While P. aeruginosa is a well-established opportunistic pathogen that deploys a diverse array of virulence factors to drive airway infections, its persistence in the airway mucosa 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 pathogen establishment.

Hypothesis. Although anaerobes are common members of the CRS microbiota, their role in promoting P. aeruginosa association with the airway epithelium remains poorly defined. We hypothesized that anaerobes facilitate P. aeruginosa attachment by degrading mucin glycoproteins that decorate the epithelial surface.

Aim. To determine whether CRS-associated anaerobic microbiota enhance P. aeruginosa colonization of the airways through mucin modification.

Methodology. Using a novel dual oxic-anoxic culture platform, Calu-3 epithelial cells were co-cultured with a CRS-derived anaerobic microbial community. Inflammatory gene expression, mucin integrity and subsequent P. aeruginosa epithelial association were assessed. Additionally, mucins isolated from anaerobe-treated cells were evaluated for their ability to promote P. aeruginosa attachment in vitro.

Results. Anaerobe exposure increased epithelial inflammatory marker gene expression and led to degradation of mucin glycoproteins. Anaerobe pre-treatment significantly enhanced P. aeruginosa association with the epithelial surface. Moreover, mucins isolated from anaerobe-treated cells promoted greater pathogen attachment in vitro compared to intact mucins.

Conclusion. CRS-associated anaerobic microbiota can remodel the sinonasal microenvironment in ways that enhance P. aeruginosa epithelial association. These findings highlight the importance of polymicrobial interactions in CRS pathogenesis and suggest that targeting anaerobe-mediated mucin degradation may represent a novel therapeutic strategy for chronic airway disease.