Fig. 5

Several mechanisms of bacterial MVs internalization into the eukaryotic cells (A-B). The attachment of OMVs with eukaryotic cells led to the compartmentalization of TLR2 into the raft. Western blotting indicated that treatment of A549 cells with filipin reduced the levels of Flotillin and Caveolin, as raft fraction. Along with these changes, TLR2 clustering also diminished lipid rafts (C). A549 cell lysates were obtained from non-treated control, formaldehyde-treated Moraxella catarrhalis (named bacteria), Moraxella catarrhalis OMVs, and filipin-treated cells + OMVs and electrophoresed in discontinuous sucrose gradients. Immunofluorescence staining of A549 cells for monitoring receptor clustering after 1-hour treatment with OMVs from wild type and/or UspA1-deficient (OMV ΔuspA1) Moraxella catarrhalis (50 μg/ml) (D). Co-localization of OMVs occurs with flotillin and TLR2. This reaction is not associated with the activity of surface OMVs UspA1. Blue nuclei were stained with DAPI (Scale bar: 20 μm) [144]. Abbreviations: ubiquitous surface proteins A1 (UspA1). (Copyright 2010, Cellular Microbiology)