The Role of Innate Immune Responses in the Outcome of Interspecies Competition for Colonization of Mucosal Surfaces

PLoS Pathogens

Adam J Ratner¹  Aaron L Nelson¹  Elena S Lysenko¹  Jeffrey N Weiser¹ 

[1] Departments of Microbiology and Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

关键词: Pneumococcus;    Haemophilus influenzae;    Species colonization;    Neutrophils;    Complement system;    Immune response;    Species interactions;    Mouse models;   

DOI  :  10.1371/journal.ppat.0010001

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Since mucosal surfaces may be simultaneously colonized by multiple species, the success of an organism may be determined by its ability to compete with co-inhabitants of its niche. To explore the contribution of host factors to polymicrobial competition, a murine model was used to study the initiation of colonization by Haemophilus influenzae and Streptococcus pneumoniae. Both bacterial species, which occupy a similar microenvironment within the nasopharynx, persisted during colonization when given individually. Co-colonization, however, resulted in rapid clearance of S. pneumoniae from the upper respiratory tract, associated with increased recruitment of neutrophils into paranasal spaces. Systemic depletion of either neutrophil-like cells or complement was sufficient to eliminate this competitive effect, indicating that clearance was likely due to enhanced opsonophagocytic killing. The hypothesis that modulation of opsonophagocytic activity was responsible for host-mediated competition was tested using in vitro killing assays with elicited neutrophil-like cells. Components of H. influenzae (but not S. pneumoniae) stimulated complement-dependent phagocytic killing of S. pneumoniae. Thus, the recruitment and activation of neutrophils through selective microbial pattern recognition may underlie the H. influenzae–induced clearance of S. pneumoniae. This study demonstrates how innate immune responses may mediate competitive interactions between species and dictate the composition of the colonizing flora.

【 授权许可】

CC BY