| 1. |
- Frick, Inga-Maria, et al.
(författare)
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Constitutive and Inflammation-Dependent Antimicrobial Peptides Produced by Epithelium Are Differentially Processed and Inactivated by the Commensal Finegoldia magna and the Pathogen Streptococcus pyogenes.
- 2011
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Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 187, s. 4300-4309
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Tidskriftsartikel (refereegranskat)abstract
- Epithelial linings serve as physical barriers and produce antimicrobial peptides (AMPs) to maintain host integrity. Examples are the bactericidal proteins midkine (MK) and BRAK/CXCL14 that are constitutively produced in the skin epidermal layer, where the anaerobic Gram-positive coccoid commensal Finegoldia magna resides. Consequently, this bacterium is likely to encounter both MK and BRAK/CXCL14, making these molecules possible threats to its habitat. In this study, we show that MK expression is upregulated during inflammation, concomitant with a strong downregulation of BRAK/CXCL14, resulting in changed antibacterial conditions. MK, BRAK/CXCL14, and the inflammation-dependent antimicrobial β-defensins human β-defensin (hBD)-2 and hBD-3 all showed bactericidal activity against both F. magna and the virulent pathogen Streptococcus pyogenes at similar concentrations. SufA, a released protease of F. magna, degraded MK and BRAK/CXCL14 but not hBD-2 nor hBD-3. Cleavage was seen at lysine and arginine residues, amino acids characteristic of AMPs. Intermediate SufA-degraded fragments of MK and BRAK/CXCL14 showed stronger bactericidal activity against S. pyogenes than F. magna, thus promoting survival of the latter. In contrast, the cysteine-protease SpeB of S. pyogenes rapidly degraded all AMPs investigated. The proteins FAF and SIC, released by F. magna and S. pyogenes, respectively, neutralized the antibacterial activity of MK and BRAK/CXCL14, protein FAF being the most efficient. Quantitation and colocalization by immunoelectron microscopy demonstrated significant levels and interactions of the molecules in in vivo and ex vivo samples. The findings reflect strategies used by a permanently residing commensal and a virulent pathogen, the latter operating during the limited time course of invasive disease.
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| 2. |
- Daleke-Schermerhorn, Maria H., et al.
(författare)
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Decoration of Outer Membrane Vesicles with Multiple Antigens by Using an Autotransporter Approach
- 2014
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 80:18, s. 5854-5865
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Tidskriftsartikel (refereegranskat)abstract
- Outer membrane vesicles (OMVs) are spherical nanoparticles that naturally shed from Gram-negative bacteria. They are rich in immunostimulatory proteins and lipopolysaccharide but do not replicate, which increases their safety profile and renders them attractive vaccine vectors. By packaging foreign polypeptides in OMVs, specific immune responses can be raised toward heterologous antigens in the context of an intrinsic adjuvant. Antigens exposed at the vesicle surface have been suggested to elicit protection superior to that from antigens concealed inside OMVs, but hitherto robust methods for targeting heterologous proteins to the OMV surface have been lacking. We have exploited our previously developed hemoglobin protease (Hbp) autotransporter platform for display of heterologous polypeptides at the OMV surface. One, two, or three of the Mycobacterium tuberculosis antigens ESAT6, Ag85B, and Rv2660c were targeted to the surface of Escherichia coli OMVs upon fusion to Hbp. Furthermore, a hypervesiculating Delta tolR Delta tolA derivative of attenuated Salmonella enterica serovar Typhimurium SL3261 was generated, enabling efficient release and purification of OMVs decorated with multiple heterologous antigens, exemplified by the M. tuberculosis antigens and epitopes from Chlamydia trachomatis major outer membrane protein (MOMP). Also, we showed that delivery of Salmonella OMVs displaying Ag85B to antigen-presenting cells in vitro results in processing and presentation of an epitope that is functionally recognized by Ag85B-specific T cell hybridomas. In conclusion, the Hbp platform mediates efficient display of (multiple) heterologous antigens, individually or combined within one molecule, at the surface of OMVs. Detection of antigen-specific immune responses upon vesicle-mediated delivery demonstrated the potential of our system for vaccine development.
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| 3. |
- Edström, Anneli, et al.
(författare)
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beta-Microseminoprotein Endows Post Coital Seminal Plasma with Potent Candidacidal Activity by a Calcium- and pH-Dependent Mechanism
- 2012
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Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 8:4, s. e1002625-
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Tidskriftsartikel (refereegranskat)abstract
- The innate immune factors controlling Candida albicans are mostly unknown. Vulvovaginal candidiasis is common in women and affects approximately 70-75% of all women at least once. Despite the propensity of Candida to colonize the vagina, transmission of Candida albicans following sexual intercourse is very rare. This prompted us to investigate whether the post coital vaginal milieu contained factors active against C. albicans. By CFU assays, we found prominent candidacidal activity of post coital seminal plasma at both neutral and the acid vaginal pH. In contrast, normal seminal plasma did not display candidacidal activity prior to acidification. By antifungal gel overlay assay, one clearing zone corresponding to a protein band was found in both post coital and normal seminal plasma, which was subsequently identified as beta-microseminoprotein. At neutral pH, the fungicidal activity of beta-microseminoprotein and seminal plasma was inhibited by calcium. By NMR spectroscopy, amino acid residue E-71 was shown to be critical for the calcium coordination. The acidic vaginal milieu unleashed the fungicidal activity by decreasing the inhibitory effect of calcium. The candidacidal activity of beta-microseminoprotein was mapped to a fragment of the C-terminal domain with no structural similarity to other known proteins. A homologous fragment from porcine beta-microseminoprotein demonstrated calcium-dependent fungicidal activity in a CFU assay, suggesting this may be a common feature for members of the beta-microseminoprotein family. By electron microscopy, beta-microseminoprotein was found to cause lysis of Candida. Liposome experiments demonstrated that beta-microseminoprotein was active towards ergosterol-containing liposomes that mimic fungal membranes, offering an explanation for the selectivity against fungi. These data identify beta-microseminoprotein as an important innate immune factor active against C. albicans and may help explain the low sexual transmission rate of Candida.
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| 4. |
- M Abdillahi, Suado, et al.
(författare)
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Collagen VI Encodes Antimicrobial Activity: Novel Innate Host Defense Properties of the Extracellular Matrix.
- 2012
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 4:4, s. 371-376
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Tidskriftsartikel (refereegranskat)abstract
- Collagen type VI is a subepithelial extracellular matrix component in airways and an adhesive substrate for oral pathogens [Bober et al.: J Innate Immun 2010;2:160-166]. Here, we report that collagen VI displays a dose-dependent antimicrobial activity against group A, C, and G streptococci by membrane disruption in physiological conditions. The data disclose previously unrecognized aspects of the extracellular matrix in innate host defense.
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| 5. |
- Svensson, Lisbeth, et al.
(författare)
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Platelet activation by Streptococcus pyogenes leads to entrapment in platelet aggregates from which bacteria subsequently escape.
- 2014
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Ingår i: Infection and Immunity. - 1098-5522. ; 82:10, s. 4307-4314
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Tidskriftsartikel (refereegranskat)abstract
- Platelet activation and aggregation has been reported to occur in response to a number of Gram-positive pathogens. Here we show that platelet aggregates induced by Streptococcus pyogenes were unstable and viable bacteria escaped from the aggregates over time. This was not due to a differential activation in response to the bacteria as compared with physiological activators. All the bacteria isolates induced significant platelet activation, including integrin activation, alpha and dense granule release, at equivalent levels to potent physiological platelet activators that induced stable aggregates. The ability to escape the aggregates and resist antibacterial effects of platelets was dependent on active protein synthesis by the bacteria within the aggregate. We conclude that S. pyogenes can temporarily cover themselves with activated platelets and we propose that this may facilitate survival of bacteria in the presence of platelets.
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