Differential interactions between Malassezia sympodialis and bacterial co-colonizers Pseudomonas aeruginosa or Staphylococcus aureus leads to distinct inflammatory responses at the airway mucosa.

Recent advances in sequencing technologies have led to a multitude of studies which relate the composition of host-associated microbiota, consisting of bacteria, fungi, viruses, and archaea, to host health status. These microbial assemblages can influence development and function of immunological features through direct or indirect interactions with the host. However, few studies have investigated whether the interspecies interactions within the microbiota can influence inflammatory responses, particularly those between bacterial and fungal community members. In this study, we identify distinct bacterial-fungal interactions between a dimorphic fungus, Malassezia sympodialis, and common sinonasal pathobionts, Pseudomonas aeruginosa and Staphylococcus aureus, that drive distinct airway immune responses. This is the first study to demonstrate that interactions within the airway microbiota can lead to distinct host immune responses, and it suggests that the future studies elucidating the complex network and outcomes of interspecies microbial interactions are critical to our understanding of chronic airway inflammatory disease.