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Version: publishedVersion × search.filters.applied.f.series: Advanced healthcare materials 11 (2022), Nr. 5 × WGL Institute: INM ×

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    An Outer Membrane Vesicle-Based Permeation Assay (OMPA) for Assessing Bacterial Bioavailability
    (Weinheim : Wiley-VCH, 2021) Richter, Robert; Kamal, Mohamed A.M.; Koch, Marcus; Niebuur, Bart-Jan; Huber, Anna-Lena; Goes, Adriely; Volz, Carsten; Vergalli, Julia; Kraus, Tobias; Müller, Rolf; Schneider-Daum, Nicole; Fuhrmann, Gregor; Pagès, Jean-Marie; Lehr, Claus-Michael
    When searching for new antibiotics against Gram-negative bacterial infections, a better understanding of the permeability across the cell envelope and tools to discriminate high from low bacterial bioavailability compounds are urgently needed. Inspired by the phospholipid vesicle-based permeation assay (PVPA), which is designed to predict non-facilitated permeation across phospholipid membranes, outer membrane vesicles (OMVs) of Escherichia coli either enriched or deficient of porins are employed to coat filter supports for predicting drug uptake across the complex cell envelope. OMVs and the obtained in vitro model are structurally and functionally characterized using cryo-TEM, SEM, CLSM, SAXS, and light scattering techniques. In vitro permeability, obtained from the membrane model for a set of nine antibiotics, correlates with reported in bacterio accumulation data and allows to discriminate high from low accumulating antibiotics. In contrast, the correlation of the same data set generated by liposome-based comparator membranes is poor. This better correlation of the OMV-derived membranes points to the importance of hydrophilic membrane components, such as lipopolysaccharides and porins, since those features are lacking in liposomal comparator membranes. This approach can offer in the future a high throughput screening tool with high predictive capacity or can help to identify compound- and bacteria-specific passive uptake pathways.
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    Yields and Immunomodulatory Effects of Pneumococcal Membrane Vesicles Differ with the Bacterial Growth Phase
    (Weinheim : Wiley-VCH, 2021) Mehanny, Mina; Kroniger, Tobias; Koch, Marcus; Hoppstädter, Jessica; Becher, Dörte; Kiemer, Alexandra K.; Lehr, Claus-Michael; Fuhrmann, Gregor
    Streptococcus pneumoniae infections are a leading cause of death worldwide. Bacterial membrane vesicles (MVs) are promising vaccine candidates because of the antigenic components of their parent microorganisms. Pneumococcal MVs exhibit low toxicity towards several cell lines, but their clinical translation requires a high yield and strong immunogenic effects without compromising immune cell viability. MVs are isolated during either the stationary phase (24 h) or death phase (48 h), and their yields, immunogenicity and cytotoxicity in human primary macrophages and dendritic cells have been investigated. Death-phase vesicles showed higher yields than stationary-phase vesicles. Both vesicle types displayed acceptable compatibility with primary immune cells and several cell lines. Both vesicle types showed comparable uptake and enhanced release of the inflammatory cytokines, tumor necrosis factor and interleukin-6, from human primary immune cells. Proteomic analysis revealed similarities in vesicular immunogenic proteins such as pneumolysin, pneumococcal surface protein A, and IgA1 protease in both vesicle types, but stationary-phase MVs showed significantly lower autolysin levels than death-phase MVs. Although death-phase vesicles produced higher yields, they lacked superiority to stationary-phase vesicles as vaccine candidates owing to their similar antigenic protein cargo and comparable uptake into primary human immune cells.