| 1. |
- Allhorn, Maria, et al.
(author)
-
Heme-Scavenging Role of alpha1-Microglobulin in Chronic Ulcers.
- 2003
-
In: Journal of Investigative Dermatology. - : Elsevier BV. - 1523-1747 .- 0022-202X. ; 121:3, s. 640-646
-
Journal article (peer-reviewed)abstract
- Chronic venous ulcers are characterized by chronic inflammation. Heme and iron, originating from blood cell hemolysis as well as extravascular necrosis, have been implicated as important pathogenic factors due to their promotion of oxidative stress. It was recently reported that the plasma and tissue protein alpha1-microglobulin is involved in heme metabolism. The protein binds heme, and a carboxy-terminally processed form, truncated alpha1-microglobulin, also degrades heme. Here, we show the presence of micromolar levels of heme and free iron in chronic leg ulcer fluids. Micromolar amounts of alpha1-microglobulin was also present in the ulcer fluids and bound to added radiolabeled heme. Truncated alpha1-microglobulin was found in the ulcer fluids and exogenously added alpha1-microglobulin was processed into the truncated alpha1-microglobulin form. Histochemical analysis of chronic wound tissue showed the presence of iron deposits, heme/porphyrins in infiltrating cells basement membranes and fibrin cuffs around vessels, and alpha1-microglobulin ubiquitously distributed but especially abundant in basement membranes around vessels and at fibrin cuffs. Our results suggest that alpha1-microglobulin constitutes a previously unknown defense mechanism against high heme and iron levels during skin wound healing. Excessive heme and iron, which are not buffered by alpha1-microglobulin, may underlie the chronic inflammation in chronic ulcers.
|
|
| 2. |
- Andersson, Emma, et al.
(author)
-
Antimicrobial activities of heparin-binding peptides.
- 2004
-
In: European Journal of Biochemistry. - : Wiley. - 0014-2956. ; 271:6, s. 1219-1226
-
Journal article (peer-reviewed)abstract
- Antimicrobial peptides are effector molecules of the innate immune system. We recently showed that the human antimicrobial peptides alpha-defensin and LL-37 bind to glycosaminoglycans (heparin and dermatan sulphate). Here we demonstrate the obverse, i.e. structural motifs associated with heparin affinity (cationicity, amphipaticity, and consensus regions) may confer antimicrobial properties to a given peptide. Thus, heparin-binding peptides derived from laminin isoforms, von Willebrand factor, vitronectin, protein C inhibitor, and fibronectin, exerted antimicrobial activities against Gram-positive and Gram-negative bacteria. Similar results were obtained using heparin-binding peptides derived from complement factor C3 as well as consensus sequences for heparin-binding (Cardin and Weintraub motifs). These sequence motifs, and additional peptides, also killed the fungus Candida albicans. These data will have implications for the search for novel antimicrobial peptides and utilization of heparin-protein interactions should be helpful in the identification and purification of novel antimicrobial peptides from complex biological mixtures. Finally, consensus regions may serve as templates for de novo synthesis of novel antimicrobial molecules.
|
|
| 3. |
- Frick, Inga-Maria, et al.
(author)
-
Interactions between M proteins of Streptococcus pyogenes and glycosaminoglycans promote bacterial adhesion to host cells.
- 2003
-
In: European Journal of Biochemistry. - : Wiley. - 0014-2956. ; 270:10, s. 2303-2311
-
Journal article (peer-reviewed)abstract
- Several microbial pathogens have been reported to interact with glycosaminoglycans (GAGs) on cell surfaces and in the extracellular matrix. Here we demonstrate that M protein, a major surface-expressed virulence factor of the human bacterial pathogen, Streptococcus pyogenes, mediates binding to various forms of GAGs. Hence, S. pyogenes strains expressing a large number of different types of M proteins bound to dermatan sulfate (DS), highly sulfated fractions of heparan sulfate (HS) and heparin, whereas strains deficient in M protein surface expression failed to interact with these GAGs. Soluble M protein bound DS directly and could also inhibit the interaction between DS and S. pyogenes. Experiments with M protein fragments and with streptococci expressing deletion constructs of M protein, showed that determinants located in the NH2-terminal part as well as in the C-repeat region of the streptococcal proteins are required for full binding to GAGs. Treatment with ABC-chondroitinase and HS lyase that specifically remove DS and HS chains from cell surfaces, resulted in significantly reduced adhesion of S. pyogenes bacteria to human epithelial cells and skin fibroblasts. Together with the finding that exogenous DS and HS could inhibit streptococcal adhesion, these data suggest that GAGs function as receptors in M protein-mediated adhesion of S. pyogenes.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Lundqvist, Katarina, et al.
(author)
-
Immunohistochemical studies on proteoglycan expression in normal skin and chronic ulcers
- 2001
-
In: British Journal of Dermatology. - : Oxford University Press (OUP). - 1365-2133 .- 0007-0963. ; 144:2, s. 254-259
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Proteoglycans (PGs) represent a large family of complex molecules. They are found either as integral membrane components or constituents of the extracellular matrix. Their protein backbones are linked to different glycosaminoglycans, such as dermatan-, chondroitin-, keratan- or heparan sulphate. The molecules have specific functions during developmental processes as well as in diseases, such as cancer and inflammation. OBJECTIVES: The expression patterns of various cell-associated heparan and chondroitin/dermatan-sulphate PGs in human skin and chronic venous ulcers were investigated. METHODS: Tissue sections from 11 patients with chronic venous ulcers were used in this study. Monoclonal antibodies were used for detection of the proteoglycans syndecan-1, -2 and -4, glypican, CD44 and perlecan. RESULTS: The different PGs exhibited individual staining patterns. Syndecan-1 and -4 and glypican expression in chronic ulcers differed from the staining in normal skin. Whereas the expression of syndecan-4 and glypican in intact skin was mostly in the pericellular regions of keratinocytes, the epidermal cells from the wound edge contained mostly intracellular PGs. In the wound edge, syndecan-4 was predominantly expressed by epidermal basal layer cells. Syndecan-1 was less expressed at the epidermal wound margins. PGs bind growth factors, regulate proteolytic activity and act as matrix receptors. CONCLUSIONS: The altered expression patterns of glypican and syndecan-1 and -4 in chronic ulcers reflect their possible roles during inflammation and cell proliferation. Hence, analysis of PG expression should be of interest in future studies on normal as well as defective wound healing.
|
|
| 7. |
|
|
| 8. |
- Schmidtchen, Artur
(author)
-
Degradation of antiproteinases, complement and fibronectin in chronic leg ulcers
- 2000
-
In: Acta Dermato-Venereologica. - : Medical Journals Sweden AB. - 1651-2057 .- 0001-5555. ; 80:3, s. 179-179
-
Journal article (peer-reviewed)abstract
- It has been proposed that excessive and uncontrolled proteolytic activity is an important pathogenetic factor for chronic wounds. Identification of molecules that either control or reflect proteolysis in wounds may prove to be useful in determining wound healing activity. In this study wound fluid was sampled under a polyurethane dressing or on hydrophilic glass filters. Multiple chronic wound fluid components were identified; viz. the previously described alpha2-macroglobulin, alpha1-antitrypsin and fibronectin, as well as "novel" wound fluid molecules such as complement factor C3, inter-alpha-inhibitor, kininogen, IgG, IgA, C-reactive protein, tetranectin, orosomucoid and ceruloplasmin. There appeared to be a highly variable degradation of alpha1-antitrypsin in the wounds; furthermore, the activation of C3 appeared to correlate with the appearance of fibronectin breakdown products. In wound fluid, inter-alpha-inhibitor was degraded. The influence of the sampling procedures was studied. It was shown that contact phase activation must be taken into account in the study of molecules (such as kininogens) activated by hydrophilic charged surfaces.
|
|
| 9. |
- Schmidtchen, Artur, et al.
(author)
-
Dermatan sulphate is released by proteinases of common pathogenic bacteria and inactivates antibacterial alpha-defensin
- 2001
-
In: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 39:3, s. 708-713
-
Journal article (peer-reviewed)abstract
- Defensins represent an evolutionarily conserved group of small peptides with potent antibacterial activities. We report here that extracellular proteinases secreted by the human pathogens Pseudomonas aeruginosa, Enterococcus faecalis and Streptococcus pyogenes release dermatan sulphate by degrading dermatan sulphate-containing proteoglycans, such as decorin. Dermatan sulphate was found to bind to neutrophil-derived alpha-defensin, and this binding completely neutralized its bactericidal activity. During infection, proteoglycan degradation and release of dermatan sulphate may therefore represent a previously unknown virulence mechanism, which could serve as a target for novel antibacterial strategies.
|
|
| 10. |
- Schmidtchen, Artur, et al.
(author)
-
Differential proteinase expression by Pseudomonas aeruginosa derived from chronic leg ulcers
- 2001
-
In: Acta Dermato-Venereologica. - : Medical Journals Sweden AB. - 1651-2057 .- 0001-5555. ; 81:6, s. 406-409
-
Journal article (peer-reviewed)abstract
- Pseudomonas aeruginosa colonizes 20-30% of all venous leg ulcers. Hypothetically, P. aeraginosa could release proteases and cytotoxic substances in the environment of chronic ulcers, thus negatively affecting the wound-healing activity in this patient group. Here we show that P. aeruginosa isolates from leg ulcers exhibit a highly variable expression of the proteinases elastase and alkaline proteinase. We propose that bacterial phenotype should be taken into account in future studies on the clinical outcome of leg ulcers colonized by P. aeruginosa.
|
|
| 11. |
|
|
| 12. |
- Schmidtchen, Artur, et al.
(author)
-
Proteinases of common pathogenic bacteria degrade and inactivate the antibacterial peptide LL-37
- 2002
-
In: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 46:1, s. 157-168
-
Journal article (peer-reviewed)abstract
- Effectors of the innate immune system, the anti-bacterial peptides, have pivotal roles in preventing infection at epithelial surfaces. Here we show that proteinases of the significant human pathogens Pseudomonas aeruginosa, Enterococcus faecalis, Proteus mirabilis and Streptococcus pyogenes, degrade the antibacterial peptide LL-37. Analysis by mass spectrometry of fragments generated by P. aeruginosa elastase in vitro revealed that the initial cleavages occurred at Asn-Leu and Asp-Phe, followed by two breaks at Arg-Ile, thus inactivating the peptide. Proteinases of the other pathogens also degraded LL-37 as determined by SDS-PAGE. Ex vivo, P. aeruginosa elastase induced LL-37 degradation in human wound fluid, leading to enhanced bacterial survival. The degradation was blocked by the metalloproteinase inhibitors GM6001 and 1, 10-phenantroline (both of which inhibited P. aeruginosa elastase, P. mirabilis proteinase, and E. faecalis gelatinase), or the inhibitor E64 (which inhibited S. pyogenes cysteine proteinase). Additional experiments demonstrated that dermatan sulphate and disaccharides of the structure [DeltaUA(2S)-GalNAc(4,6S)], or sucroseoctasulphate, in-hibited the degradation of LL-37. The results indicate that proteolytic degradation of LL-37 is a common virulence mechanism and that molecules which block this degradation could have therapeutic potential.
|
|
| 13. |
- Werthen, M, et al.
(author)
-
Pseudomonas aeruginosa-induced infection and degradation of human wound fluid and skin proteins ex vivo are eradicated by a synthetic cationic polymer
- 2004
-
In: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 1460-2091 .- 0305-7453. ; 54:4, s. 772-779
-
Journal article (peer-reviewed)abstract
- Objectives: Antimicrobial peptides are important effectors of innate immunity. Bacteria display multiple defence mechanisms against these peptides. For example, Pseudomonas aeruginosa releases potent proteinases that inactivate the human cathelicidin LL-37. Hence, in conditions characterized by persistent bacterial colonization, such as in P. aeruginosa-infected skin wounds, there is a need for efficient means of reducing bacterial load. Here, the effect of the cationic molecule polyhexamethylenebiguanide (PHMB) was evaluated. Methods: Infection models in human wound fluid and human skin were established. Radial diffusion methods, bacterial growth and bactericidal assays were used for determination of effects of PHMB on bacteria in the presence of plasma, wound fluid or human skin. At the protein and tissue levels, SDS-PAGE, light microscopy and scanning electron microscopy were used to study the effects of P. aeruginosa infection before and after addition of PHMB. Results: PHMB killed common ulcer-derived bacteria in the presence of human wound fluid. Furthermore, elastase-expressing P. aeruginosa completely degraded wound fluid proteins as well as human skin during infection ex vivo. The infection, and consequent protein degradation, was reversed by PHMB. Conclusions: The ex vivo infection models presented here should be helpful in the screening of novel antimicrobials and constitute a prerequisite for future clinical studies.
|
|
