| 1. |
- Gram, Magnus, et al.
(författare)
-
Up-Regulation of A1M/α(1)-Microglobulin in Skin by Heme and Reactive Oxygen Species Gives Protection from Oxidative Damage.
- 2011
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:11
-
Tidskriftsartikel (refereegranskat)abstract
- During bleeding the skin is subjected to oxidative insults from free heme and radicals, generated from extracellular hemoglobin. The lipocalin α(1)-microglobulin (A1M) was recently shown to have reductase properties, reducing heme-proteins and other substrates, and to scavenge heme and radicals. We investigated the expression and localization of A1M in skin and the possible role of A1M in the protection of skin tissue from damage induced by heme and reactive oxygen species. Skin explants, keratinocyte cultures and purified collagen I were exposed to heme, reactive oxygen species, and/or A1M and investigated by biochemical methods and electron microscopy. The results demonstrate that A1M is localized ubiquitously in the dermal and epidermal layers, and that the A1M-gene is expressed in keratinocytes and up-regulated after exposure to heme and reactive oxygen species. A1M inhibited the heme- and reactive oxygen species-induced ultrastructural damage, up-regulation of antioxidation and cell cycle regulatory genes, and protein carbonyl formation in skin and keratinocytes. Finally, A1M bound to purified collagen I (K(d) = 0.96×10(-6) M) and could inhibit and repair the destruction of collagen fibrils by heme and reactive oxygen species. The results suggest that A1M may have a physiological role in protection of skin cells and matrix against oxidative damage following bleeding.
|
|
| 2. |
|
|
| 3. |
- Pasupuleti, Mukesh, et al.
(författare)
-
Antimicrobial activity of human prion protein is mediated by its N-terminal region
- 2009
-
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 4:10, s. e7358-
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cellular prion-related protein (PrP(c)) is a cell-surface protein that is ubiquitously expressed in the human body. The multifunctionality of PrP(c), and presence of an exposed cationic and heparin-binding N-terminus, a feature characterizing many antimicrobial peptides, made us hypothesize that PrP(c) could exert antimicrobial activity. METHODOLOGY AND PRINCIPAL FINDINGS: Intact recombinant PrP exerted antibacterial and antifungal effects at normal and low pH. Studies employing recombinant PrP and N- and C-terminally truncated variants, as well as overlapping peptide 20mers, demonstrated that the antimicrobial activity is mediated by the unstructured N-terminal part of the protein. Synthetic peptides of the N-terminus of PrP killed the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, and the Gram-positive Bacillus subtilis and Staphylococcus aureus, as well as the fungus Candida parapsilosis. Fluorescence studies of peptide-treated bacteria, paired with analysis of peptide effects on liposomes, showed that the peptides exerted membrane-breaking effects similar to those seen after treatment with the "classical" human antimicrobial peptide LL-37. In contrast to LL-37, however, no marked helix induction was detected for the PrP-derived peptides in presence of negatively charged (bacteria-mimicking) liposomes. PrP furthermore showed an inducible expression during wounding of human skin ex vivo and in vivo, as well as stimulation of keratinocytes with TGF-alpha in vitro. CONCLUSIONS: The demonstration of an antimicrobial activity of PrP, localisation of its activity to the N-terminal and heparin-binding region, combined with results showing an increased expression of PrP during wounding, indicate that PrPs could have a previously undisclosed role in host defense.
|
|
| 4. |
- Roupé, Karl Markus, et al.
(författare)
-
Transcription Factor Binding Site Analysis Identifies FOXO Transcription Factors as Regulators of the Cutaneous Wound Healing Process.
- 2014
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:2
-
Tidskriftsartikel (refereegranskat)abstract
- The search for significantly overrepresented and co-occurring transcription factor binding sites in the promoter regions of the most differentially expressed genes in microarray data sets could be a powerful approach for finding key regulators of complex biological processes. To test this concept, two previously published independent data sets on wounded human epidermis were re-analyzed. The presence of co-occurring transcription factor binding sites for FOXO1, FOXO3 and FOXO4 in the majority of the promoter regions of the most significantly differentially expressed genes between non-wounded and wounded epidermis implied an important role for FOXO transcription factors during wound healing. Expression levels of FOXO transcription factors during wound healing in vivo in both human and mouse skin were analyzed and a decrease for all FOXOs in human wounded skin was observed, with FOXO3 having the highest expression level in non wounded skin. Impaired re-epithelialization was found in cultures of primary human keratinocytes expressing a constitutively active variant of FOXO3. Conversely knockdown of FOXO3 in keratinocytes had the opposite effect and in an in vivo mouse model with FOXO3 knockout mice we detected significantly accelerated wound healing. This article illustrates that the proposed approach is a viable method for identifying important regulators of complex biological processes using in vivo samples. FOXO3 has not previously been implicated as an important regulator of wound healing and its exact function in this process calls for further investigation.
|
|
| 5. |
|
|
| 6. |
- Borregaard, Niels, et al.
(författare)
-
Neutrophil granules: a library of innate immunity proteins
- 2007
-
Ingår i: Trends in Immunology. - : Elsevier BV. - 1471-4981 .- 1471-4906. ; 28:8, s. 340-345
-
Forskningsöversikt (refereegranskat)abstract
- Gene expression profiling has revealed that circulating neutrophils rest between two major bursts of transcriptional and protein synthetic activities. The first occurs in the bone marrow. This equips the neutrophil with stocks of innate defense armory that are packaged into different granule subsets. The second burst occurs when the neutrophil exits circulation and migrates into tissues to find, capture and phagocytose microorganisms. This burst results in the synthesis and secretion of cytokines and chemokines that support resolution of inflammation and healing of damaged tissue. Gene expression profiling has revealed that neutrophils express a variety of innate immunity proteins, known previously only to be expressed in other cells. Likewise, it has become clear that some proteins previously thought to be specific to the neutrophil are expressed in epithelial cells during inflammation.
|
|
| 7. |
- Boughan, PK, et al.
(författare)
-
Nucleotide-binding oligomerization domain-1 and epidermal growth factor receptor - Critical regulators of beta-defensins during helicobacter pylori infection
- 2006
-
Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 281:17, s. 11637-11648
-
Tidskriftsartikel (refereegranskat)abstract
- Host-pathogen interactions that allow Helicobacter pylori to survive and persist in the stomach of susceptible individuals remain unclear. Human beta-defensins ( hBDs), epithelial-derived antimicrobial peptides are critical components of host-defense at mucosal surfaces. The role of H. pylori-mediated NF-kappa B and epidermal growth factor receptor ( EGFR) activation on beta-defensin expression was investigated. Transient transfection studies utilizing beta-defensin promoter constructs were conducted in gastric cells with contribution of individual signaling events evaluated by the addition of specific inhibitors, small interference nucleotide-binding oligomerization domain 1( NOD1) RNA or plasmids encoding Vaccinia virus proteins that interrupt interleukin-1 and Toll-like receptor signaling. The role of individual MAPK pathways was further delineated in HEK-293 cells expressing conditional MAPK mutants. We found hBD2 expression exclusively dependent on the presence of the bacterial cag pathogenicity island, with NOD1 a critical host sensor. Impairment of murine beta-defensin 4( an orthologue of hBD2) expression in NOD1-deficient mice 7-days post-infection further confirmed the role of this cytoplasmic pattern-recognition receptor in eliciting host innate immunity. In contrast to hBD2, hBD3 expression was NOD1-independent but EGFR and ERK pathway-dependent. Importantly, Toll-like receptor signaling was not implicated in H. pylori-mediated hBD2 and hBD3 gene expression. The divergent signaling events governing hBD2 and hBD3 expression suggest temporal functional variation, such that hBD2 may contribute to antimicrobial barrier function during the inflammatory phase with hBD3 playing a greater role during the repair, wound healing phase of infection.
|
|
| 8. |
- Cederlund, Martin, et al.
(författare)
-
A1M/α1-microglobulin is proteolytically activated by myeloperoxidase, binds its heme group and inhibits low density lipoprotein oxidation.
- 2015
-
Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- α1-microglobulin (A1M) is a 26 kDa plasma and tissue protein with reductase activity and radical- and heme-binding anti-oxidative functions. In addition, exposure of A1M to hemoglobin has been shown to induce proteolytic elimination of a C-terminal tetrapeptide yielding a heme-degrading form, truncated A1M (t-A1M). Myeloperoxidase (MPO), a heme-containing enzyme that catalyzes the production of free radicals and hypochlorite, is released by neutrophils during the inflammatory response to bacterial infections. MPO-induced low density lipoprotein (LDL)-oxidation in blood has been suggested as a causative factor in atherosclerosis. In this study we have hypothesized that A1M interacts with MPO in a similar mode as with hemoglobin, and is a regulator of its activity. The results show that A1M is proteolytically cleaved, with formation of t-A1M, after exposure to MPO, and that t-A1M contains iron and heme-degradation products. The reaction is dependent of pH, time and concentration of substrates and a pH-value around 7 is shown to be optimal for cleavage. Furthermore, A1M inhibits MPO- and hydrogen peroxide-induced oxidation of LDL. The results suggest that A1M may have a role as an inhibitor of the damaging effects of the neutrophil respiratory burst on bystander tissue components.
|
|
| 9. |
- Eliasson, Mette, et al.
(författare)
-
M1 protein of Streptococcus pyogenes increases production of the antibacterial CXC chemokine MIG/CXCL9 in pharyngeal epithelial cells
- 2007
-
Ingår i: Microbial Pathogenesis. - : Elsevier BV. - 1096-1208 .- 0882-4010. ; 43:5-6, s. 224-233
-
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.
|
|
| 10. |
- Hurley, Sinead, et al.
(författare)
-
Platelet-dependent neutrophil function is dysregulated by M protein from Streptococcus pyogenes.
- 2015
-
Ingår i: Infection and Immunity. - 1098-5522. ; 83:9, s. 3515-3525
-
Tidskriftsartikel (refereegranskat)abstract
- Platelets are rapidly responsive sentinel cells that patrol the bloodstream and contribute to the host response to infection. Platelets have been reported to form heterotypic aggregates with leukocytes and may modulate their function. Herein we have investigated platelet-neutrophil complex formation and neutrophil function in response to distinct agonists. The endogenous platelet activator thrombin gave rise to platelet-dependent neutrophil activation, resulting in enhanced phagocytosis and bacterial killing. Streptococcus pyogenes is an important causative agent of severe infectious disease, which can manifest as sepsis and septic shock. M1 protein from S. pyogenes also mediated platelet-neutrophil complex formation, however these neutrophils were dysfunctional and exhibited diminished chemotactic ability and bacterial killing. This reveals an important agonist dependent neutrophil dysfunction during platelet-neutrophil complex formation, and highlights the role of platelets during the immune response to streptococcal infection.
|
|
