Open AccessMulticomponent Moraxella catarrhalis outer membrane vesicles induce an inflammatory response and are internalized by human epithelial cells
Author(s) -
Schaar Viveka,
de Vries Stefan P. W.,
Perez Vidakovics Maria Laura A.,
Bootsma Hester J.,
Larsson Lennart,
Hermans Peter W. M.,
Bjartell Anders,
Mörgelin Matthias,
Riesbeck Kristian
Publication year - 2011
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2010.01546.x
Subject(s) - moraxella catarrhalis , bacterial outer membrane , biology , moraxella (branhamella) catarrhalis , microbiology and biotechnology , bacterial adhesin , secretion , tlr2 , virulence , immune system , inflammation , innate immune system , immunology , streptococcus pneumoniae , biochemistry , escherichia coli , gene , antibiotics
Summary Moraxella catarrhalis is an emerging human respiratory pathogen in patients with chronic obstructive pulmonary disease (COPD) and in children with acute otitis media. The specific secretion machinery known as outer membrane vesicles (OMVs) is a mechanism by which Gram‐negative pathogens interact with host cells during infection. We identified 57 proteins in M. catarrhalis OMVs using a proteomics approach combining two‐dimensional SDS‐PAGE and MALDI‐TOF mass spectrometry analysis. The OMVs contained known surface proteins such as ubiquitous surface proteins (Usp) A1/A2, and Moraxella IgD‐binding protein (MID). Most of the proteins are adhesins/virulence factors triggering the immune response, but also aid bacteria to evade the host defence. FITC‐stained OMVs bound to lipid raft domains in alveolar epithelial cells and were internalized after interaction with Toll‐like receptor 2 (TLR2), suggesting a delivery to the host tissue of a large and complex group of OMV‐attributed proteins. Interestingly, OMVs modulated the pro‐inflammatory response in epithelial cells, and UspA1‐bearing OMVs were found to specifically downregulate the reaction. When mice were exposed to OMVs, a pulmonary inflammation was clearly seen. Our findings indicate that Moraxella OMVs are highly biologically active, transport main bacterial virulence factors and may modulate the epithelial pro‐inflammatory response.