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| 2. |
- Eliasson, Mette, et al.
(författare)
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M1 protein of Streptococcus pyogenes increases production of the antibacterial CXC chemokine MIG/CXCL9 in pharyngeal epithelial cells
- 2007
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Ingår i: Microbial Pathogenesis. - : Elsevier BV. - 1096-1208 .- 0882-4010. ; 43:5-6, s. 224-233
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pyogenes adheres to epithelial cells of the human pharynx where it can cause pharyngitis. To counteract infection. inflamed epithelium produces peptide antibiotics, among them the CXC chemokine MIG/CXCL9. M protein is both a surface-associated and released virulence factor of S. pyogenes. Here we show that soluble M1 protein enhances MIG gene expression and synthesis in IFN-gamma stimulated epithelial cells. M1 protein was recognized both by resting and IFN-gamma activated pharyngeal epithelial cells as detected by activation of the transcription factor NF-kappa B. Furthermore, pharmacological inhibition of NF-kappa B. decreased MIG synthesis in IFN-gamma activated cells, demonstrating a key role for NF-kappa B in mediating the enhanced response. Microarrays were used to investigate expression of recognized antimicrobial peptides in pharyngeal epithelial cells after stimulation with a combination of IFN-gamma and M1 protein. Amongst the most up-regulated and expressed genes, were several antibacterial CC and CXC chemokines. To investigate all in vivo context, pharyngeal mucosa was stimulated in vitro and MIG could be detected by immunohistochemistry in epithelial cells. The results show that epithelial cells can recognize solubilized M I protein and intact S. pyogenes, thereby modulating an antibacterial innate host response that may have bearing oil the outcome of streptococcal pharyngitis.
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| 3. |
- Nardella, F A, et al.
(författare)
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Fc epitopes for human rheumatoid factors and the relationships of rheumatoid factors to the Fc binding proteins of microorganisms
- 1988
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Ingår i: Scandinavian Journal of Rheumatology. Supplement. - : Informa UK Limited. - 1502-7740 .- 0300-9742 .- 1502-7732. ; 17:Suppl. 75, s. 190-198
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Tidskriftsartikel (refereegranskat)abstract
- Work from our laboratories has shown that the major antigenic determinants for rheumatoid factors (RFs) are in the C gamma 2-C gamma 3 interface region of IgG in the same area that binds staphylococcal protein A (SPA). Furthermore, the Fc binding proteins of groups A, C and G streptococci as well as the Fc binding proteins induced on cell surfaces by herpes simplex virus type I also bind to the same area of IgG. These binding site similarities between RFs and the microbial Fc binding proteins suggested conformational similarities between the RF antigen combining regions and the Fc binding regions of the microbial proteins. This hypothesis was supported by the observation that antibodies to SPA bind to the antigen combining regions of most RFs as well as to the Fc binding region of the T15 group A streptococcal Fc binding protein. These findings indicate that RFs bear the conformational internal image of these microbial proteins and suggest that RFs could arise as antibodies to the idiotypic determinants on antibodies to microbial Fc binding proteins. Alternatively, microbial Fc binding proteins could present IgG to the immune system in a way that renders specific areas of the C gamma 2-C gamma 3 interface region immunogenic. These relationships between RFs and microbial Fc binding proteins may prove to be important for our understanding of the generation of RFs in rheumatoid arthritis.
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| 4. |
- Ryan, Mary H, et al.
(författare)
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Proteolysis of purified IgGs by human and bacterial enzymes in vitro and the detection of specific proteolytic fragments of endogenous IgG in rheumatoid synovial fluid
- 2008
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Ingår i: Molecular Immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 45:7, s. 1837-1846
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Tidskriftsartikel (refereegranskat)abstract
- A comparative in vitro survey of physiologically relevant human and microbial proteinases defined a number of enzymes that induced specific hinge domain cleavage in human IgG1. Several of these proteinases have been associated with tumor growth, inflammation, and infection. A majority of the identified proteinases converted IgG to F(ab')(2), and a consistent feature of their action was a transient accumulation of a single-cleaved intermediate (scIgG). The scIgG resulted from the relatively rapid cleavage of the first hinge domain heavy chain, followed by a slower cleavage of the second chain to separate the Fc domain from F(ab')(2). Major sites of enzymatic cleavage were identified or confirmed from the mass of the F(ab')(2) or Fab fragments and/or the amino-terminal amino acid sequence of the Fc for each enzyme including human matrix metalloprotemases (MMPs) 3 and 12, human cathepsin G, human neutrophil elastase (Fab), staphylococcal glutamyl endopeptidase I and streptococcal immunoglobulin-degrading enzyme (Ides). The cleavage sites in IgG1 by MMP-3, cathepsin G and Ides were used to guide the synthesis of peptide analogs containing the corresponding carboxy-termini to be used as immunogens in rabbits. Rabbit antibodies were successfully generated that showed selective binding to different human F(ab')(2)s and other hinge-cleavage fragments, but not to intact IgG. In Western blotting studies of synovial fluids from individuals with rheumatoid arthritis, the rabbit antibodies yielded patterns consistent with the presence of endogenous IgG fragments including F(ab')(2) and the single-cleaved IgG intermediate. The detection in synovial fluid of IgG fragments similar to those observed in the in vitro biochemical studies suggests that proteolysis of IgG may contribute to localized immune dysfunction in inflammatory environments.
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| 5. |
- Shannon, Oonagh, et al.
(författare)
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Histidine-rich glycoprotein promotes bacterial entrapment in clots and decreases mortality in a mouse model of sepsis.
- 2010
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 116, s. 2365-2372
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pyogenes is a significant bacterial pathogen in humans. In this study, Histidine-rich glycoprotein (HRG), an abundant plasma protein, was found to kill S. pyogenes. Furthermore, S. pyogenes grew more efficiently in HRG deficient plasma, and clots formed in this plasma were significantly less effective at bacterial entrapment and killing. HRG deficient mice were strikingly more susceptible to S. pyogenes infection. These animals failed to control the infection at the local subcutaneous site, and abscess formation and inflammation was diminished as compared with control animals. As a result, bacterial dissemination occurred more rapidly in HRG deficient mice and they succumbed earlier and with a significantly higher mortality rate than control animals. HRG deficient mice supplemented with purified HRG gave the same phenotype as control animals, demonstrating that the lack of HRG was responsible for the increased susceptibility. The results demonstrate a previously unappreciated role for HRG as a regulator of inflammation and in the defence at the local site of bacterial infection.
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| 6. |
- Viau, Muriel, et al.
(författare)
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Specific in vivo deletion of B-cell subpopulations expressing human immunoglobulins by the B-cell superantigen protein L
- 2004
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Ingår i: Infection and Immunity. - 1098-5522. ; 72:6, s. 3515-3523
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Tidskriftsartikel (refereegranskat)abstract
- Some pathogens have evolved to produce proteins, called B-cell superantigens, that can interact with human immunoglobulin variable regions, independently of the combining site, and activate B lymphocytes that express the target immunoglobulins. However, the in vivo consequences of these interactions on human B-cell numbers and function are largely unknown. Using transgenic mice expressing fully human immunoglobulins, we studied the consequences of in vivo exposure of protein L of Peptostreptococcus magnus with human immunoglobulins. In the mature pool of B cells, protein L exposure resulted in a specific reduction of splenic marginal-zone B cells and peritoneal B-1 cells. Splenic B cells exhibited a skewed light-chain repertoire consistent with the capacity of protein L to bind specific kappa gene products. Remarkably, these two B-cell subsets are implicated in innate B-cell immunity, allowing rapid clearance of pathogens. Thus, the present study reveals a novel mechanism that may be used by some infectious agents to subvert a first line of the host's immune defense.
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