| 1. |
- Alkaissi, Lina Y., et al.
(författare)
-
Antagonism of Adherent Invasive E. coli LF82 With Human α-defensin 5 in the Follicle-associated Epithelium of Patients With Ileal Crohn’s Disease
- 2021
-
Ingår i: Inflammatory Bowel Diseases. - : OXFORD UNIV PRESS INC. - 1078-0998 .- 1536-4844. ; 27:7, s. 1116-1127
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The first visible signs of Crohns disease (CD) are microscopic erosions over the follicle-associated epithelium (FAE). The aim of the study was to investigate the effects of human alpha-defensin 5 (HD5) on adherent-invasive Escherichia coli LF82 translocation and HD5 secretion after LF82 exposure in an in vitro model of human FAE and in human FAE ex vivo. Methods: An in vitro FAE-model was set up by the coculture of Raji B cells and Caco-2-cl1 cells. Ileal FAE from patients with CD and controls were mounted in Ussing chambers. The effect of HD5 on LF82 translocation was studied by LF82 exposure to the cells or tissues with or without incubation with HD5. The HD5 secretion was measured in human FAE exposed to LF82 or Salmonella typhimurium. The HD5 levels were evaluated by immunofluorescence, immunoblotting, and ELISA. Results: There was an increased LF82 translocation across the FAE-model compared with Caco-2-cl1 (P < 0.05). Incubation of cell/tissues with HD5 before LF82 exposure reduced bacterial passage in both models. Human FAE showed increased LF82 translocation in CD compared with controls and attenuated passage after incubation with sublethal HD5 in both CD and controls (P < 0.05). LF82 exposure resulted in a lower HD5 secretion in CD FAE compared with controls (P < 0.05), whereas Salmonella exposure caused equal secretion on CD and controls. There were significantly lower HD5 levels in CD tissues compared with controls. Conclusions: Sublethal HD5 reduces the ability of LF82 to translocate through FAE. The HD5 is secreted less in CD in response to LF82, despite a normal response to Salmonella. This further implicates the integrated role of antimicrobial factors and barrier function in CD pathogenesis.
|
|
| 2. |
|
|
| 3. |
- Küchler, Robert, et al.
(författare)
-
Antimicrobial activity of high-mobility-group box 2 : a new function to a well-known protein.
- 2013
-
Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 57:10, s. 4782-93
-
Tidskriftsartikel (refereegranskat)abstract
- The human intestinal tract is highly colonized by a vast number of microorganisms. Despite this permanent challenge, infections remain rare, due to a very effective barrier defense system. Essential effectors of this system are antimicrobial peptides and proteins (AMPs), which are secreted by intestinal epithelial and lymphoid cells, balance the gut microbial community, and prevent the translocation of microorganisms. Several antimicrobial proteins have already been identified in the gut. Nonetheless, we hypothesized that additional AMPs are yet to be discovered in this setting. Using biological screening based on antimicrobial function, here we identified competent antibacterial activity of high-mobility-group box 2 (HMGB2) against Escherichia coli. By recombinant expression, we confirmed this biologically new antimicrobial activity against different commensal and pathogenic bacteria. In addition, we demonstrated that the two DNA-binding domains (HMG boxes A and B) are crucial for the antibiotic function. We detected HMGB2 in several gastrointestinal tissues by mRNA analysis and immunohistochemical staining. In addition to the nuclei, we also observed HMGB2 in the cytoplasm of intestinal epithelial cells. Furthermore, HMGB2 was detectable in vitro in the supernatants of two different cell types, supporting an extracellular function. HMGB2 expression was not changed in inflammatory bowel disease but was detected in certain stool samples of patients, whereas it was absent from control individuals. Taken together, we characterized HMGB2 as an antimicrobial protein in intestinal tissue, complementing the diverse repertoire of gut mucosal defense molecules.
|
|
| 4. |
- Nuding, Sabine, et al.
(författare)
-
Gastric Antimicrobial Peptides Fail to Eradicate Helicobacter pylori Infection Due to Selective Induction and Resistance
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:9
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Although antimicrobial peptides protect mucus and mucosa from bacteria, Helicobacter pylori is able to colonize the gastric mucus. To clarify in which extend Helicobacter escapes the antimicrobial defense, we systematically assessed susceptibility and expression levels of different antimicrobial host factors in gastric mucosa with and without H. pylori infection.Materials and Methods: We investigated the expression levels of HBD1 (gene name DEFB1), HBD2 (DEFB4A), HBD3 (DEFB103A), HBD4 (DEFB104A), LL37 (CAMP) and elafin (PI3) by real time PCR in gastric biopsy samples in a total of 20 controls versus 12 patients colonized with H. pylori. Immunostaining was performed for HBD2 and HBD3. We assessed antimicrobial susceptibility by flow cytometry, growth on blood agar, radial diffusion assay and electron microscopy.Results: H. pylori infection was associated with increased gastric levels of the inducible defensin HBD2 and of the antiprotease elafin, whereas the expression levels of the constitutive defensin HBD1, inducible HBD3 and LL37 remained unchanged. HBD4 was not expressed in significant levels in gastric mucosa. H. pylori strains were resistant to the defensins HBD1 as well as to elafin, and strain specific minimally susceptible to HBD2, whereas HBD3 and LL37 killed all H. pylori strains effectively. We demonstrated the binding of HBD2 and LL37 on the surface of H. pylori cells. Comparing the antibacterial activity of extracts from H. pylori negative and positive biopsies, we found only a minimal killing against H. pylori that was not increased by the induction of HBD2 in H. pylori positive samples.Conclusion: These data support the hypothesis that gastric H. pylori evades the host defense shield to allow colonization.
|
|
| 5. |
- Schröder, Björn, et al.
(författare)
-
Intestinales Mikrobiom und Schleimhautbarriere
- 2021
-
Ingår i: Intestinales Mikrobiom und Innere Medizin. - : UNI-MED Verlag AG. - 9783837416053 ; , s. 39-45
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Das intestinale Mikrobiom repräsentiert aktuell eines der Topthemen, die im Fokus der modernen Humanmedizin stehen. Doch erstaunlicherweise gab es bisher im deutschen Sprachraum keine handliche, aktuelle Übersicht zu diesem Thema. Daher werden in diesem Band zunächst Zusammensetzung und Dynamik des humanen intestinalen Mikrobioms erläutert, ehe in weiteren Kapiteln dann die wichtigsten Veränderungen und vor allem die Rolle des Mikrobioms bei zahlreichen Krankheiten wie chronisch entzündlichen Darmerkrankungen, Reizdarmsyndrom, Leber- und Gallenwegs- sowie Autoimmunerkrankungen diskutiert werden. Es folgen der Komplex Ernährung, Adipositas und Diabetes sowie Atherosklerose mit jeweils eigenen Kapiteln. Schließlich gibt es überraschende Beziehungen der Mikrobiota zur Malignomentstehung. Es folgt ein Abschnitt über Antibiotika und deren Rolle bei zum Teil dauerhaften Störungen der intestinalen Bakterien und Pilze. Am Ende des Buches wird am Beispiel von Mikrobiomtransfer (“Stuhltransplantation”) und Probiotika auf die therapeutischen Konsequenzen eingegangen. Alle Kapitel sind auch für sich lesbar und verständlich.
|
|
| 6. |
- Schröder, Björn, et al.
(författare)
-
Intestinales Mikrobiom und Schleimhautbarriere bei chronisch entzündlichen Darmerkrankungen
- 2021
-
Ingår i: Intestinales Mikrobiom und Innere Medizin. - : UNI-MED Verlag AG. - 9783837416053 ; , s. 46-55
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Das intestinale Mikrobiom repräsentiert aktuell eines der Topthemen, die im Fokus der modernen Humanmedizin stehen. Doch erstaunlicherweise gab es bisher im deutschen Sprachraum keine handliche, aktuelle Übersicht zu diesem Thema. Daher werden in diesem Band zunächst Zusammensetzung und Dynamik des humanen intestinalen Mikrobioms erläutert, ehe in weiteren Kapiteln dann die wichtigsten Veränderungen und vor allem die Rolle des Mikrobioms bei zahlreichen Krankheiten wie chronisch entzündlichen Darmerkrankungen, Reizdarmsyndrom, Leber- und Gallenwegs- sowie Autoimmunerkrankungen diskutiert werden. Es folgen der Komplex Ernährung, Adipositas und Diabetes sowie Atherosklerose mit jeweils eigenen Kapiteln. Schließlich gibt es überraschende Beziehungen der Mikrobiota zur Malignomentstehung. Es folgt ein Abschnitt über Antibiotika und deren Rolle bei zum Teil dauerhaften Störungen der intestinalen Bakterien und Pilze. Am Ende des Buches wird am Beispiel von Mikrobiomtransfer ("Stuhltransplantation") und Probiotika auf die therapeutischen Konsequenzen eingegangen. Alle Kapitel sind auch für sich lesbar und verständlich.
|
|
| 7. |
- Schröder, Björn O., et al.
(författare)
-
Waking the wimp : Redox-modulation activates human beta-defensin 1
- 2011
-
Ingår i: Gut microbes. - : Taylor & Francis. - 1949-0976 .- 1949-0984. ; 2:4, s. 262-266
-
Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial peptides are key players of the innate immune system and form a primary barrier against infection by microorganisms. In humans, several classes of antimicrobial peptides are produced, including the defensins. These small, cationic peptides show broad spectrum antimicrobial activity against bacteria, some fungi and some viruses. Defensins are characterized by six conserved cysteine residues which are connected via three disulphide bridges. Depending on the pattern of connectivity, human defensins are either classified as α- or β-defensins. Human β-defensin 1 (hBD-1) is constitutively expressed by epithelia, but in comparison with other antimicrobial peptides the antimicrobial activity of hBD-1 was comparably low. We recently found that after reduction of hBD-1's three disulphide bonds its antimicrobial activity is strongly enhanced. Reduction can be either performed by a reducing environment, as it is present in parts of the human intestine, the oral cavity and other locations, or enzymatically by the thioredoxin-system, which is one of the major redox regulators. Reduced hBD-1 is able to kill Gram-positive anaerobic bacteria of the human normal flora as well as an opportunistic pathogenic fungus, whereas the oxidized peptide does not show activity against these microorganisms. Herein we provide additional data about reduced hBD-1 and discuss the biological context of our findings.
|
|
| 8. |
- Schröder, Björn, et al.
(författare)
-
Reduction of disulphide bonds unmasks potent antimicrobial activity of human β-defensin 1
- 2011
-
Ingår i: Nature. - : Macmillan Publishers Ltd.. - 0028-0836 .- 1476-4687. ; 469:7330, s. 419-423
-
Tidskriftsartikel (refereegranskat)abstract
- Human epithelia are permanently challenged by bacteria and fungi, including commensal and pathogenic microbiota. In the gut, the fraction of strict anaerobes increases from proximal to distal, reaching 99% of bacterial species in the colon. At colonic mucosa, oxygen partial pressure is below 25% of airborne oxygen content, moreover microbial metabolism causes reduction to a low redox potential of -200 mV to -300 mV in the colon. Defensins, characterized by three intramolecular disulphide-bridges, are key effector molecules of innate immunity that protect the host from infectious microbes and shape the composition of microbiota at mucosal surfaces. Human β-defensin 1 (hBD-1) is one of the most prominent peptides of its class but despite ubiquitous expression by all human epithelia, comparison with other defensins suggested only minor antibiotic killing activity. Whereas much is known about the activity of antimicrobial peptides in aerobic environments, data about reducing environments are limited. Herein we show that after reduction of disulphide-bridges hBD-1 becomes a potent antimicrobial peptide against the opportunistic pathogenic fungus Candida albicans and against anaerobic, Gram-positive commensals of Bifidobacterium and Lactobacillus species. Reduced hBD-1 differs structurally from oxidized hBD-1 and free cysteines in the carboxy terminus seem important for the bactericidal effect. In vitro, the thioredoxin (TRX) system is able to reduce hBD-1 and TRX co-localizes with reduced hBD-1 in human epithelia. Hence our study indicates that reduced hBD-1 shields the healthy epithelium against colonisation by commensal bacteria and opportunistic fungi. Accordingly, an intimate interplay between redox-regulation and innate immune defence seems crucial for an effective barrier protecting human epithelia.
|
|
| 9. |
- Stange, Eduard F., et al.
(författare)
-
Microbiota and mucosal defense in IBD : an update
- 2019
-
Ingår i: Expert Review of Gastroenterology & Hepatology. - : Taylor & Francis. - 1747-4124 .- 1747-4132. ; 13:10, s. 963-976
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Inflammatory bowel diseases (IBD) are on the rise worldwide. This review covers the current concepts of the etiology of Crohn?s disease and ulcerative colitis by focusing on an unbalanced interaction between the intestinal microbiota and the mucosal barrier. Understanding these issues is of paramount importance for the development of targeted therapies aiming at the disease cause.Area covered: Gut microbiota alterations and a dysfunctional intestinal mucosa are associated with IBD. Here we focus on specific defense structures of the mucosal barrier, namely antimicrobial peptides and the mucus layer, which keep the gut microbiota at a distance under healthy conditions and are defective in IBD.Expert commentary: The microbiology of both forms of IBD is different but characterized by a reduced bacterial diversity and richness. Abundance of certain bacterial species is altered, and the compositional changes are related to disease activity. In IBD the mucus layer above the epithelium is contaminated by bacteria and the immune reaction is dominated by the antibacterial response. Human genetics suggest that many of the basic deficiencies in the mucosal response, due to Paneth cell, defensin and mucus defects, are primary. Nutrition may also be important but so far there is no therapy targeting the mucosal barrier.
|
|
| 10. |
- Troge, Anja, et al.
(författare)
-
More than a marine propeller--the flagellum of the probiotic Escherichia coli strain Nissle 1917 is the major adhesin mediating binding to human mucus.
- 2012
-
Ingår i: International Journal of Medical Microbiology. - : Elsevier BV. - 1438-4221 .- 1618-0607. ; 302:7-8, s. 304-14
-
Tidskriftsartikel (refereegranskat)abstract
- The flagellum of the probiotic Escherichia coli strain Nissle 1917 (EcN) is not just responsible for motility, but also for EcN's ability to induce the production of human β-defensin 2. Here, we report a third function of this EcN organell. In this study we investigated the role of the EcN flagellum in adhesion to different host tissues by ex vivo and in vitro studies. Ex vivo studies with cryosections of human gut biopsies revealed that the flagellum of EcN is most likely important for efficient adhesion to the human intestinal tract. These results and in vitro studies with different epithelial cells indicated that the presence of mucus is important for efficient mediation of adhesion by the flagellum of EcN. We observed direct interaction between isolated flagella from EcN wild type and porcine mucin 2 as well as human mucus. However, we could not observe any interaction of the flagella with murine mucus. For the first time, we identified the mucus component gluconate as one receptor for the binding of flagella from EcN and were able to exclude the flagellin domain D3 as a responsible interaction partner. We propose that the flagellum of EcN is its major adhesin in vivo, which enables this probiotic strain to compete efficiently for binding sites on host tissue with several bacterial pathogens.
|
|
