| 1. |
- Bober, Marta, et al.
(författare)
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Collagen VI Is a Subepithelial Adhesive Target for Human Respiratory Tract Pathogens
- 2010
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 2:2, s. 160-166
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial engagement of specific host tissue structures can be a means of targeting a pathogen to a particular niche, establishing persistent infections and inducing invasion. In this context, primary adhesion is often the first crucial colonization step allowing pathogens to withstand the mechanical clearing mechanisms of the host. As a consequence, bacteria have evolved adhesins with the capacity to mediate interaction between microorganism and host. Here we describe Collagen VI as a novel target for adherence of Streptococcus pyogenes and Streptococcus pneumoniae. In upper and lower airways this Collagen was distributed in the lamina propria underneath the epithelial basement membrane. Both pathogens exhibited strong affinity to Collagen VI as shown by light and electron microscopy in combination with immunodetection and in vitro binding assays. For S. pyogenes this interaction was mediated by M1 protein. The presented data provide evidence for a previously unrecognized role for Collagen VI in host-pathogen interplay during respiratory tract infection. Copyright (C) 2009 S. Karger AG, Basel
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| 2. |
- Bober, Marta
(författare)
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Molecular and microscopical analysis of pathogenic streptococci - studies on surface proteins interacting with human cells and extracellular matrix
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Association to specific host tissue structures allows pathogenic bacteria to establish an infection and facilitates the spread within its host. Interactions between bacterial surface structures and human proteins might determine the outcome of the infection. Streptococcus pyogenes (S. pyogenes), is a human pathogen mostly causing localized infections of the skin and respiratory tract, but it is also capable of causing severe invasive disease such as necrotizing fasciitis, sepsis and toxic shock. Until recently, S. pyogenes has been considered as a strictly extracellular pathogen, but several studies has shown that it is capable of invading and surviving intracellularly in several human cell types. In this thesis I have investigated the interaction of S. pyogenes and Streptococcus pneumoniae (S. pneumoniae) with collagen type VI, the binding of S. pyogenes M1 protein and leucine rich (Slr) protein to collagen type I, and Slr’s interaction with human keratinocytes. The adherence of S. pyogenes and S. pneumoniae to collagen type VI in murine upper and lower airways was restricted to the proximity of the NH2 - and COOH-terminal globular domains of collagen type VI, and for S. pyogenes this interaction was mediated by the M1 protein. The M1 protein and Slr are co-expressed on the bacterial surface and both bind to collagen type I with high affinity. Slr exhibited multiple binding sites to collagen I, both to the monomeric and the fibrillar structure, with the most binding concentrated to the overlap region of the collagen I fibril. Slr is able to adhere to and internalize into human keratinocytes (HaCaT) cells in a time dependent manner and we were able to identify non-muscle myosin IIA as a potential cellular ligand for Slr. We could further confirm the presence of non-muscle myosin IIA in HaCat cell lysate and that Slr binds to non-muscle myosin IIA. In summary, we have characterized a novel adhesin of S. pyogenes, Slr, as a LRR containing lipoprotein that, in concert with the M1 protein, might utilize collagens as adhesive targets during the infection process. Slr and M1 bind to collagen type I, and M1 also binds to collagen type VI, a process that might play a role in the primary step of infection in the skin and respiratory tract. Furthermore, Slr binds to non-muscle myosin IIA possibly resulting in the bacterial adherence to and internalization into human keratinocytes. This could contribute to S. pyogenes avoidance of the immune system and/or bacterial dissemination into deeper tissues.
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| 3. |
- Bober, Marta, et al.
(författare)
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The membrane bound LRR lipoprotein Slr, and the cell wall-anchored M1 protein from Streptococcus pyogenes both interact with type I collagen.
- 2011
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Ingår i: PloS one. - : Public Library of Science. - 1932-6203. ; 6:5, s. e20345-
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pyogenes is an important human pathogen and surface structures allow it to adhere to, colonize and invade the human host. Proteins containing leucine rich repeats (LRR) have been identified in mammals, viruses, archaea and several bacterial species. The LRRs are often involved in protein-protein interaction, are typically 20-30 amino acids long and the defining feature of the LRR motif is an 11-residue sequence LxxLxLxxNxL (x being any amino acid). The streptococcal leucine rich (Slr) protein is a hypothetical lipoprotein that has been shown to be involved in virulence, but at present no ligands for Slr have been identified. We could establish that Slr is a membrane attached horseshoe shaped lipoprotein by homology modeling, signal peptidase II inhibition, electron microscopy (of bacteria and purified protein) and immunoblotting. Based on our previous knowledge of LRR proteins we hypothesized that Slr could mediate binding to collagen. We could show by surface plasmon resonance that recombinant Slr and purified M1 protein bind with high affinity to collagen I. Isogenic slr mutant strain (MB1) and emm1 mutant strain (MC25) had reduced binding to collagen type I as shown by slot blot and surface plasmon resonance. Electron microscopy using gold labeled Slr showed multiple binding sites to collagen I, both to the monomeric and the fibrillar structure, and most binding occurred in the overlap region of the collagen I fibril. In conclusion, we show that Slr is an abundant membrane bound lipoprotein that is co-expressed on the surface with M1, and that both these proteins are involved in recruiting collagen type I to the bacterial surface. This underlines the importance of S. pyogenes interaction with extracellular matrix molecules, especially since both Slr and M1 have been shown to be virulence factors.
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| 4. |
- Garbe, Julia, et al.
(författare)
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EndoE from Enterococcus faecalis Hydrolyzes the Glycans of the Biofilm Inhibiting Protein Lactoferrin and Mediates Growth.
- 2014
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- Glycosidases are widespread among bacteria. The opportunistic human pathogen Enterococcus faecalis encodes several putative glycosidases but little is known about their functions. The identified endo-β-N-acetylglucosaminidase EndoE has activity on the N-linked glycans of the human immunoglobulin G (IgG). In this report we identified the human glycoprotein lactoferrin (hLF) as a new substrate for EndoE. Hydrolysis of the N-glycans from hLF was investigated using lectin blot, UHPLC and mass spectrometry, showing that EndoE releases major glycoforms from this protein. hLF was shown to inhibit biofilm formation of E. faecalis in vitro. Glycans of hLF influence the binding to E. faecalis, and EndoE-hydrolyzed hLF inhibits biofilm formation to lesser extent than intact hLF indicating that EndoE prevents the inhibition of biofilm. In addition, hLF binds to a surface-associated enolase of E. faecalis. Culture experiments showed that the activity of EndoE enables E. faecalis to use the glycans derived from lactoferrin as a carbon source indicating that they could be used as nutrients in vivo when no other preferred carbon source is available. This report adds important information about the enzymatic activity of EndoE from the commensal and opportunist E. faecalis. The activity on the human glycoprotein hLF, and the functional consequences with reduced inhibition of biofilm formation highlights both innate immunity functions of hLF and a bacterial mechanism to evade this innate immunity function. Taken together, our results underline the importance of glycans in the interplay between bacteria and the human host, with possible implications for both commensalism and opportunism.
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| 5. |
- M Abdillahi, Suado, et al.
(författare)
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Collagen VI Is Upregulated in COPD and Serves Both as an Adhesive Target and a Bactericidal Barrier for Moraxella catarrhalis.
- 2015
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 7:5, s. 506-517
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Tidskriftsartikel (refereegranskat)abstract
- Moraxella catarrhalis is a Gram-negative human mucosal commensal and pathogen. It is a common cause of exacerbation in chronic obstructive pulmonary disease (COPD). During the process of infection, host colonization correlates with recognition of host molecular patterns. Importantly, in COPD patients with compromised epithelial integrity the underlying extracellular matrix is exposed and provides potential adhesive targets. Collagen VI is a ubiquitous fibrillar component in the airway mucosa and has been attributed both adhesive and killing properties against Gram-positive bacteria. However, less is known regarding Gram-negative microorganisms. Therefore, in the present study, the interaction of M. catarrhalis with collagen VI was characterized. We found that collagen VI is upregulated in the airways of COPD patients and exposed upon epithelial desquamation. Ex vivo, we inoculated airway biopsies and fibroblasts from COPD patients with M. catarrhalis. The bacteria specifically adhered to collagen VI-containing matrix fibrils. In vitro, purified collagen VI microfibrils bound to bacterial surface structures. The primary adhesion target was mapped to the collagen VI α2-chain. Upon exposure to collagen VI, bacteria were killed by membrane destabilization in physiological conditions. These previously unknown properties of collagen VI provide novel insights into the extracellular matrix innate immunity by quickly entrapping and killing pathogen intruders. © 2015 S. Karger AG, Basel.
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