Partners in slime: How mucus regulates microbial virulence

Mucus is a biological gel that lines all wet epithelia in the body, including the mouth, lungs, and digestive tracts, and has evolved to protect us from pathogenic invasion. Microbial pathogenesis in these mucosal systems, however, is often studied in mucus- free environments, which lack the geometric constraints and microbial interactions that are found in natural, three- dimensional mucus gels. My laboratory has developed model test systems to understand how the mucus barrier influences microbial virulence, and moreover, to elucidate strategies used by microbes to overcome the normal protective mucus barrier. We show that mucin polymers, and specifically their associated glycans, significantly impact the physiological behavior of microbes, including surface attachment, quorum sensing, the expression of virulence genes, and biofilm formation. The picture is emerging that mucin glycans are key host players in the regulation of microbial virulence and underscores the untapped therapeutic opportunities found in these host-derived molecules.