Corynebacterium Species Inhibit Streptococcus pneumoniae Colonization and Infection of the Mouse Airway

The stability and composition of the airway microbiome is an important determinant of respiratory health. Some airway bacteria are considered to be beneficial due to their potential to impede the acquisition and persistence of opportunistic bacterial pathogens such as . Among such organisms, the presence of species correlates with reduced in both adults and children, in whom abundance is predictive of infection risk. Previously, was shown to express a lipase which cleaves host lipids, resulting in the production of fatty acids that inhibit growth of . However, it was unclear whether this mechanism contributes to - interactions . To address this question, we developed a mouse model for colonization in which colonization with either or another species, , significantly reduced acquisition in the upper airway and infection in the lung. Moreover, the lungs of co-infected mice had reduced pro-inflammatory cytokines and inflammatory myeloid cells, indicating resolution of infection-associated inflammation. The inhibitory effect of on was mediated by lipase-dependent and independent effects, indicating that both this and other bacterial factors contribute to -mediated protection in the airway. We also identified a previously uncharacterized bacterial lipase in that is required for inhibition of growth . Together, these findings demonstrate the protective potential of airway species and establish a new model for investigating the impact of commensal microbiota, such as , on maintaining respiratory health.