Open AccessPili play an important role in enhancing the bacterial clearance from the middle ear in a mouse model of acute otitis media with M oraxella catarrhalis
Author(s) -
Kawano Toshiaki,
Hirano Takashi,
Kodama Satoru,
Mitsui Marcelo Takahiro,
Ahmed Kamruddin,
Nishizono Akira,
Suzuki Masashi
Publication year - 2013
Publication title -
pathogens and disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.983
H-Index - 105
ISSN - 2049-632X
DOI - 10.1111/2049-632x.12025
Subject(s) - moraxella catarrhalis , pilus , tlr5 , microbiology and biotechnology , moraxella (branhamella) catarrhalis , middle ear , otitis , biology , tlr2 , flagellin , immunology , innate immune system , immune system , haemophilus influenzae , bacteria , gene , virulence , antibiotics , biochemistry , genetics , anatomy
M oraxella catarrhalis is a G ram‐negative aerobic diplococcus that is currently the third most frequent cause of bacterial acute otitis media ( AOM ) in children. In this study, we developed an experimental murine AOM model by inoculating M . catarrhalis in the middle ear bulla and studied the local response to this inoculation, and modulation of its course by the pili of M . catarrhalis . The pili‐positive and pili‐negative M . catarrhalis showed differences in bacterial clearance and infiltration of inflammatory cells in the middle ear. Pili‐negative M . catarrhalis induced a more delayed and prolonged immune response in the middle ear than that of pili‐positive M . catarrhalis . TLR 2 , ‐4 , ‐5 and ‐9 m RNA expression was upregulated in neutrophils that infiltrated the middle ear cavity during AOM caused by both pili‐positive and pili‐negative bacteria. TLR5 m RNA expression and TLR5 protein in the neutrophils were induced more robustly by pili‐positive M . catarrhalis . This immune response is likely to be related to neutrophil function such as toll‐like 5‐dependent phagocytosis. Our results show that mice may provide a useful AOM model for studying the role of M . catarrhalis . Furthermore, we show that pili play an important role in enhancing M . catarrhalis clearance from the middle ear that is probably mediated through neutrophil‐dependent TLR5 signaling.