| 1. |
- Al Adwani, Salma, et al.
(författare)
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Citrullination Alters the Antibacterial and Anti-Inflammatory Functions of the Host Defense Peptide Canine Cathelicidin K9CATH In Vitro
- 2021
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 207:3, s. 974-984
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Tidskriftsartikel (refereegranskat)abstract
- K9CATH is the sole cathelicidin in canines (dogs) and exhibits broad antimicrobial activity against both Gram-positive and Gram-negative bacteria. K9CATH also modulates inflammatory responses and binds to LPS. These activities depend on the secondary structure and a net-positive charge of the peptide. Peptidylarginine deiminases (PAD) convert cationic peptidyl arginine to neutral citrulline. Thus, we hypothesized that citrullination is a biologically relevant modification of the peptide that would reduce the antibacterial and LPS-binding activities of K9CATH. Recombinant PAD2 and PAD4 citrullinated K9CATH to various extents and circular dichroism spectroscopy revealed that both native and citrullinated K9CATH exhibited similar α-helical secondary structures. Notably, citrullination of K9CATH reduced its bactericidal activity, abolished its ability to permeabilize the membrane of Gram-negative bacteria and reduced the hemolytic capacity. Electron microscopy showed that citrullinated K9CATH did not cause any morphological changes of Gram-negative bacteria, whereas the native peptide caused clear alterations of membrane integrity, concordant with a rapid bactericidal effect. Finally, citrullination of K9CATH impaired its capacity to inhibit LPS-mediated release of proinflammatory molecules from mouse and canine macrophages. In conclusion, citrullination attenuates the antibacterial and the LPS-binding properties of K9CATH, demonstrating the importance of a net positive charge for antibacterial lysis of bacteria and LPS-binding effects and suggests that citrullination is a means to regulate cathelicidin activities.
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| 2. |
- Bergman, Peter, et al.
(författare)
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Induction of the antimicrobial peptide CRAMP in the blood-brain barrier and meninges after meningococcal infection
- 2006
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 74:12, s. 6982-6991
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial peptides are present in most living species and constitute important effector molecules of innate immunity. Recently, we and others have detected antimicrobial peptides in the brain. This is an organ that is rarely infected, which has mainly been ascribed to the protective functions of the blood-brain barrier (BBB) and meninges. Since the bactericidal properties of the BBB and meninges are not known, we hypothesized that antimicrobial peptides could play a role in these barriers. We addressed this hypothesis by infecting mice with the neuropathogenic bacterium Neisseria meningitidis. Brains were analyzed for expression of the antimicrobial peptide CRAMP by immunohistochemistry in combination with confocal microscopy. After infection, we observed induction of CRAMP in endothelial cells of the BBB and in cells of the meninges. To explore the functional role of CRAMP in meningococcal disease, we infected mice deficient of the CRAMP gene. Even though CRAMP did not appear to protect the brain from invasion of meningococci, CRAMP knockout mice were more susceptible to meningococcal infection than wild-type mice and exhibited increased meningococcal growth in blood, liver, and spleen. Moreover, we could demonstrate that carbonate, a compound that accumulates in the circulation during metabolic acidosis, makes meningococci more susceptible to CRAMP.
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| 3. |
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| 4. |
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| 5. |
- Coorens, Maarten, et al.
(författare)
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Innate lymphoid cell type 3-derived interleukin-22 boosts lipocalin-2 production in intestinal epithelial cells via synergy between STAT3 and NF-B
- 2019
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 294:15, s. 6027-6041
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Tidskriftsartikel (refereegranskat)abstract
- Escherichia coli and Klebsiella pneumoniae are opportunistic pathogens that are commonly associated with infections at mucosal surfaces, such as the lung or the gut. The host response against these types of infections includes the release of epithelial-derived antimicrobial factors such as lipocalin-2 (LCN-2), a protein that specifically inhibits the iron acquisition of Enterobacteriaceae by binding and neutralizing the bacterial iron-scavenging molecule enterobactin. Regulation of epithelial antimicrobial responses, including the release of LCN-2, has previously been shown to depend on IL-22, a cytokine produced by innate lymphoid cells type 3 (ILC3) during Enterobacteriaceae infections. However, much remains unknown about the extent to which antimicrobial responses are regulated by IL-22 and how IL-22 regulates the expression and production of LCN-2 in intestinal epithelial cells (IECs). Our study demonstrates how IL-22-induced activation of STAT3 synergizes with NF-B-activating cytokines to enhance LCN-2 expression in human IECs and elucidates how ILC3 are involved in LCN-2-mediated host defense against Enterobacteriaceae. Together, these results provide new insight into the role of ILC3 in regulating LCN-2 expression in human IECs and could prove useful in future studies aimed at understanding the host response against Enterobacteriaceae as well as for the development of antimicrobial therapies against Enterobacteriaceae-related infections.
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| 6. |
- Johansson, Linda, et al.
(författare)
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Cathelicidin LL-37 in Severe Streptococcus pyogenes Soft Tissue Infections in Humans
- 2008
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Ingår i: Infection and Immunity. - 1098-5522. ; 76:8, s. 3399-3404
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Tidskriftsartikel (refereegranskat)abstract
- Severe soft tissue infections, such as necrotizing fasciitis and severe cellulitis, caused by group A streptococcus (GAS) are rapidly progressing life-threatening infections characterized by massive bacterial load in the tissue even late after onset of infection. Antimicrobial peptides are important components of the innate host defence and cathelicidins have been shown to protect against murine necrotic skin infection caused by GAS. However, the streptococcal cysteine protease SpeB has been demonstrated to proteolytically inactivate the human cathelicidin LL-37 in vitro. Here we have investigated the expression of LL-37 and its interaction with GAS and SpeB during acute severe soft tissue infections by analyses of patient tissue biopsies. The results showed high amounts of LL-37, both the proform (hCAP18) and the mature peptide, present in the tissue. Confocal microscopy identified neutrophils as the main source of the peptide. A distinct co-localization between the bacteria and LL-37 could be noted, and bacterial load showed a positive correlation to the LL-37 levels. Areas with high LL-37 levels coincided with areas with high amounts of SpeB. Confocal microscopy confirmed a strong co-localization of GAS, SpeB and LL-37 at the bacterial surface. Taken together the findings of this study provides in vivo support that SpeB-mediated inactivation of LL-37 at the streptococcal surface represent a bacterial resistance mechanism at the infected tissue site in patients with severe GAS tissue infections.
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| 7. |
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| 8. |
- Muvva, Jagadeeswara Rao, et al.
(författare)
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Immunomodulatory Agents Combat Multidrug-Resistant Tuberculosis by Improving Antimicrobial Immunity
- 2021
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press. - 0022-1899 .- 1537-6613. ; 224:2, s. 332-344
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Tidskriftsartikel (refereegranskat)abstract
- Background. Multidrug-resistant (MDR) tuberculosis has low treatment success rates, and new treatment strategies are needed. We explored whether treatment with active vitamin D-3 (vitD) and phenylbutyrate (PBA) could improve conventional chemotherapy by enhancing immune-mediated eradication of Mycobacterium tuberculosis. Methods. A clinically relevant model was used consisting of human macrophages infected with M. tuberculosis isolates (n = 15) with different antibiotic resistance profiles. The antimicrobial effect of vitD+PBA, was tested together with rifampicin or isoniazid. Methods included colony-forming units (intracellular bacterial growth), messenger RNA expression analyses (LL-37, beta-defensin, nitric oxide synthase, and dual oxidase 2), RNA interference (LL-37-silencing in primary macrophages), and Western blot analysis and confocal microscopy (LL-37 and LC3 protein expression). Results. VitD+PBA inhibited growth of clinical MDR tuberculosis strains in human macrophages and strengthened intracellular growth inhibition of rifampicin and isoniazid via induction of the antimicrobial peptide LL-37 and I,C3-dependent autophagy. Gene silencing of LL-37 expression enhanced MDR tuberculosis growth in vitD+PBA-treated macrophages. Me combination of vitD+PBA and isoniazid were as effective in reducing intracellular MDR tuberculosis growth as a >125-fold higher dose of isoniazid alone, suggesting potent additive effects of vitD+PBA with isoniazid. Conclusions. Immunomodulatory agents that trigger multiple immune pathways can strengthen standard MDR tuberculosis treatment and contribute to next-generation individualized treatment options for patients with difficult-to-treat pulmonary tuberculosis.
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| 9. |
- Odeberg, Jacob, et al.
(författare)
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A novel cysteine-linked antibacterial surface coating significantly inhibits bacterial colonization of nasal silicone prongs in a phase one pre-clinical trial
- 2018
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : ELSEVIER SCIENCE BV. - 0928-4931 .- 1873-0191. ; 93, s. 782-789
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Tidskriftsartikel (refereegranskat)abstract
- Ventilator associated pneumonia and sepsis are frequent complications in neonatal care. Bacterial colonization of medical devices and interfaces used for respiratory support may contribute by functioning as a bacterial reservoir seeding bacteria into airways. We have developed an antibacterial surface coating based on a cysteine ligand covalently coupled via a spacer to a carboxylic backbone layer on an acrylic acid grafted silicone surface. This coating was applied on a commercially available nasal prong and the antibacterial effect was evaluated both in vitro and in vivo in a first-in-human phase 1 trial. The coated nasal prongs had strong antibacterial activity against both Gram-negative and Gram-positive bacteria in vitro. In a randomized pre-clinical trial study of 24 + 24 healthy adult volunteers who carried coated or non-coated nasal prongs for 18 h, a (10)log difference in mean bacterial colonization of 5.82 (p < 0.0001) was observed. These results show that this coating technique can prevent colonization by the normal skin and mucosal flora, and thus represent a promising novel technology for reduction of medical device-associated hospital acquired infections.
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| 10. |
- Soehnlein, Oliver, et al.
(författare)
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Neutrophil primary granule proteins HBP and HNP1-3 boost bacterial phagocytosis by human and murine macrophages.
- 2008
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Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 118:10, s. 3491-3502
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Tidskriftsartikel (refereegranskat)abstract
- In acute inflammation, infiltrating polymorphonuclear leukocytes (also known as PMNs) release preformed granule proteins having multitudinous effects on the surrounding environment. Here we present what we believe to be a novel role for PMN-derived proteins in bacterial phagocytosis by both human and murine macrophages. Exposure of macrophages to PMN secretion markedly enhanced phagocytosis of IgG-opsonized Staphylococcus aureus both in vitro and in murine models in vivo. PMN secretion activated macrophages, resulting in upregulation of the Fcgamma receptors CD32 and CD64, which then mediated the enhanced phagocytosis of IgG-opsonized bacteria. The phagocytosis-stimulating activity within the PMN secretion was found to be due to proteins released from PMN primary granules; thorough investigation revealed heparin-binding protein (HBP) and human neutrophil peptides 1-3 (HNP1-3) as the mediators of the macrophage response to PMN secretion. The use of blocking antibodies and knockout mice revealed that HBP acts via beta(2) integrins, but the receptor for HNP1-3 remained unclear. Mechanistically, HBP and HNP1-3 triggered macrophage release of TNF-alpha and IFN-gamma, which acted in an autocrine loop to enhance expression of CD32 and CD64 and thereby enhance phagocytosis. Thus, we attribute what may be a novel role for PMN granule proteins in regulating the immune response to bacterial infections.
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