| 1. |
- Alaridah, Nader, et al.
(författare)
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Mycobacteria Manipulate G-Protein-Coupled Receptors to Increase Mucosal Rac1 Expression in the Lungs
- 2017
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 9, s. 318-329
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Tidskriftsartikel (refereegranskat)abstract
- Mycobacterium bovis bacille Calmette-Guérin (BCG) is currently the only approved vaccine against tuberculosis (TB). BCG mimics M. tuberculosis (Mtb) in its persistence in the body and is used as a benchmark to compare new vaccine candidates. BCG was originally designed for mucosal vaccination, but comprehensive knowledge about its interaction with epithelium is currently lacking. We used primary airway epithelial cells (AECs) and a murine model to investigate the initial events of mucosal BCG interactions. Furthermore, we analysed the impact of the G-protein-coupled receptors (GPCRs), CXCR1 and CXCR2, in this process, as these receptors were previously shown to be important during TB infection. BCG infection of AECs induced GPCR-dependent Rac1 up-regulation, resulting in actin redistribution. The altered distribution of the actin cytoskeleton involved the MAPK signalling pathway. Blocking of the CXCR1 or CXCR2 prior to infection decreased Rac1 expression, and increased epithelial transcriptional activity and epithelial cytokine production. BCG infection did not result in epithelial cell death as measured by p53 phosphorylation and annexin. This study demonstrated that BCG infection of AECs manipulated the GPCRs to suppress epithelial signalling pathways. Future vaccine strategies could thus be improved by targeting GPCRs.
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| 2. |
- Andersson, Anna-Maria, et al.
(författare)
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Efferocytosis of Apoptotic Neutrophils Enhances Control of Mycobacterium tuberculosis in HIV-Coinfected Macrophages in a Myeloperoxidase-Dependent Manner
- 2020
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Ingår i: Journal of Innate Immunity. - : KARGER. - 1662-811X .- 1662-8128. ; 12:3, s. 235-247
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Tidskriftsartikel (refereegranskat)abstract
- Tuberculosis remains a big threat, with 1.6 million deaths in 2017, including 0.3 million deaths among patients with HIV. The risk of developing active disease increases considerably during an HIV coinfection. Alveolar macrophages are the first immune cells to encounter the causative agent Mycobacterium tuberculosis, but during the granuloma formation other cells are recruited in order to combat the bacteria. Here, we have investigated the effect of efferocytosis of apoptotic neutrophils by M. tuberculosis and HIV-coinfected macrophages in a human in vitro system. We found that the apo-ptotic neutrophils enhanced the control of M. tuberculosis in single and HIV-coinfected macrophages, and that this was dependent on myeloperoxidase (MPO) and reactive oxygen species in an autophagy-independent manner. We show that MPO remains active in the apoptotic neutrophils and can be harnessed by infected macrophages. In addition, MPO inhibition removed the suppression in M. tuberculosis growth caused by the apoptotic neutrophils. Antimycobacterial components from apoptotic neutrophils could thus increase the microbicidal activity of macrophages during an M. tuberculosis/HIV coinfection. This cooperation between innate immune cells could thereby be a way to compensate for the impaired adaptive immunity against M. tuberculosis seen during a concurrent HIV infection.
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| 3. |
- Arefin, Badrul, et al.
(författare)
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Genome-Wide Transcriptional Analysis of Drosophila Larvae Infected by Entomopathogenic Nematodes Shows Involvement of Complement, Recognition and Extracellular Matrix Proteins
- 2014
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 6:2, s. 192-204
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Tidskriftsartikel (refereegranskat)abstract
- Heterorhabditis bacteriophora is an entomopathogenic nematode (EPN) which infects its host by accessing the hemolymph where it releases endosymbiotic bacteria of the species Photorhabdus luminescens. We performed a genome-wide transcriptional analysis of the Drosophila response to EPN infection at the time point at which the nematodes reached the hemolymph either via the cuticle or the gut and the bacteria had started to multiply. Many of the most strongly induced genes have been implicated in immune responses in other infection models. Mapping of the complete set of differentially regulated genes showed the hallmarks of a wound response, but also identified a large fraction of EPN-specific transcripts. Several genes identified by transcriptome profiling or their homologues play protective roles during nematode infections. Genes that positively contribute to controlling nematobacterial infections encode: a homolog of thioester-containing complement protein 3, a basement membrane component (glutactin), a recognition protein (GNBP-like 3) and possibly several small peptides. Of note is that several of these genes have not previously been implicated in immune responses.
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| 4. |
- Aucott, H, et al.
(författare)
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Neuroinflammation in Response to Intracerebral Injections of Different HMGB1 Redox Isoforms
- 2018
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Ingår i: Journal of innate immunity. - : S. Karger AG. - 1662-8128 .- 1662-811X. ; 10:3, s. 215-227
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Tidskriftsartikel (refereegranskat)abstract
- <b><i>Background:</i></b> Neuroinflammation triggered by infection or trauma is the cause of central nervous system dysfunction. High-mobility group box 1 protein (HMGB1), released from stressed and dying brain cells, is a potent neuroinflammatory mediator. The proinflammatory functions of HMGB1 are tightly regulated by post-translational redox modifications, and we here investigated detailed neuroinflammatory responses induced by the individual redox isoforms. <b><i>Methods:</i></b> Male Dark Agouti rats received a stereotactic injection of saline, lipopolysaccharide, disulfide HMGB1, or fully reduced HMGB1, and were accessed for blood-brain barrier modifications using magnetic resonance imaging (MRI) and inflammatory responses by immunohistochemistry. <b><i>Results and Conclusions:</i></b> Significant blood-brain barrier disruption appeared 24 h after injection of lipopolysaccharide, disulfide HMGB1, or fully reduced HMGB1 compared to controls, as assessed in post-gadolinium T1-weighted MRI images and confirmed by increased uptake of FITC-conjugated dextran. Immunohistochemistry revealed that both HMGB1 isoforms also induced a local production of IL-1β. Additionally, disulfide HMGB1 increased major histocompatibility complex class II expression and apoptosis. Together, the results demonstrate that extracellular, cerebral HMGB1 causes significant blood-brain barrier disruption in a redox-independent manner and activates several components of neuroinflammation. Blocking HMGB1 might potentially improve clinical outcome in conditions such as stroke and traumatic brain injury.
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| 5. |
- Aung, Kyaw Min, et al.
(författare)
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Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U
- 2016
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 8:3, s. 269-283
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Tidskriftsartikel (refereegranskat)abstract
- Cholera epidemics are caused by Vibrio cholerae serogroups O1 and O139, whereas strains collectively known as non-O1/non-O139 V. cholerae are found in cases of extraintestinal infections and bacteremia. The mechanisms and factors influencing the occurrence of bacteremia and survival of V. cholerae in normal human serum have remained unclear. We found that naturally occurring IgG recognizing V. cholerae outer membrane protein U (OmpU) mediates a serum-killing effect in a complement C1q-dependent manner. Moreover, outer membrane vesicles (OMVs) containing OmpU caused enhanced survival of highly serum-sensitive classical V. cholerae in a dose-dependent manner. OMVs from wild-type and ompU mutant V. cholerae thereby provided a novel means to verify by extracellular transcomplementation the involvement of OmpU. Our data conclusively indicate that loss, or reduced expression, of OmpU imparts resistance to V. cholerae towards serum killing. We propose that the difference in OmpU protein levels is a plausible reason for differences in serum resistance and the ability to cause bacteremia observed among V. cholerae biotypes. Our findings provide a new perspective on how naturally occurring antibodies, perhaps induced by members of the microbiome, may play a role in the recognition of pathogens and the provocation of innate immune defense against bacteremia.
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| 6. |
- Bengtson, Sara, et al.
(författare)
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Activation of TAFI on the Surface of Streptococcus pyogenes Evokes Inflammatory Reactions by Modulating the Kallikrein/Kinin System
- 2009
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 1:1, s. 18-28
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Tidskriftsartikel (refereegranskat)abstract
- Bacteria-controlled regulation of host responses to infection is an important virulence mechanism that has been demonstrated to contribute to disease progression. Here we report that the human pathogen Streptococcus pyogenes employs the procarboxypeptidase TAR (thrombin-activatablefibrinolysis inhibitor) to modulate the kallikrein/kinin system. To this end, bacteria initiate a chain of events starting with the recruitment and activation of TAFI. This is followed by the assembly and induction of the contact system at the streptococcal surface, eventually triggering the release of bradykinin (BK). BK is then carboxyterminally truncated by activated TAFI, which converts the peptide from a kinin B-2 receptor ligand to a kinin B-1 receptor (B1R) agonist. Finally, we show that streptococcal supernatants indirectly amplify the B1R response as they act on peripheral blood mononuclear cells to secrete inflammatory cytokines that in turn stimulate upregulation of the B1R on human fibroblasts. Taken together our findings implicate a critical and novel role for streptococci-bound TAR, as it processes BK to a B1R agonist at the bacterial surface and thereby may redirect inflammation from a transient to a chronic state. Copyright (C) 2008 S. Karger AG, Basel
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| 7. |
- Berkestedt, Ingrid, et al.
(författare)
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Elevated Plasma Levels of Antimicrobial Polypeptides in Patients with Severe Sepsis.
- 2010
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 2:5, s. 478-482
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Tidskriftsartikel (refereegranskat)abstract
- We wanted to investigate if plasma levels of antimicrobial polypeptides (AMPs) are increased in severe sepsis and if they correlate with severity and mortality. Samples were collected from 31 sepsis patients at the intensive care unit. The Sequential Organ Failure Assessment (SOFA) score and 90-day mortality were registered, and inflammatory markers and AMP levels were measured by ELISA. A median SOFA score (13) and cardiovascular SOFA score (3) indicated multiorgan failure with severe circulatory derangement, and elevated cytokine levels indicated inflammatory activation. Levels of bactericidal/permeability-increasing protein, heparin-binding protein, alpha-defensins and lactoferrin but not LL-37 were elevated in sepsis patients compared with controls. Bactericidal/permeability-increasing protein levels correlated with mortality, with lower levels in survivors. Levels of all AMPs, except LL-37, positively correlated with the cardiovascular SOFA score. In conclusion, levels of several AMPs are increased in sepsis and correlate with circulatory derangement. This probably reflects neutrophil activation as part of an innate immune response.
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| 8. |
- Bernhard, Stefan, et al.
(författare)
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Interleukin 8 Elicits Rapid Physiological Changes in Neutrophils That Are Altered by Inflammatory Conditions
- 2021
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Ingår i: Journal of Innate Immunity. - : S. Karger. - 1662-811X .- 1662-8128. ; 13, s. 225-241
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Tidskriftsartikel (refereegranskat)abstract
- A sufficient response of neutrophil granulocytes stimulated by interleukin (IL)-8 is vital during systemic inflammation, for example, in sepsis or severe trauma. Moreover, IL-8 is clinically used as biomarker of inflammatory processes. However, the effects of IL-8 on cellular key regulators of neutrophil properties such as the intracellular pH (pH(i)) in dependence of ion transport proteins and during inflammation remain to be elucidated. Therefore, we investigated in detail the fundamental changes in pH(i), cellular shape, and chemotactic activity elicited by IL-8. Using flow cytometric methods, we determined that the IL-8-induced cellular activity was largely dependent on specific ion channels and transporters, such as the sodium-proton exchanger 1 (NHE1) and non-NHE1-dependent sodium flux. Exposing neutrophils in vitro to a proinflammatory micromilieu with N-formyl-Met-Leu-Phe, LPS, or IL-8 resulted in a diminished response regarding the increase in cellular size and pH. The detailed kinetics of the reduced reactivity of the neutrophil granulocytes could be illustrated in a near-real-time flow cytometric measurement. Last, the LPS-mediated impairment of the IL-8-induced response in neutrophils was confirmed in a translational, animal-free human whole blood model. Overall, we provide novel mechanistic insights for the interaction of IL-8 with neutrophil granulocytes and report in detail about its alteration during systemic inflammation.
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| 9. |
- Bidla, Gawa, et al.
(författare)
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Activation of Insect Phenoloxidase after Injury : Endogenous versus Foreign Elicitors
- 2009
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 1:4, s. 301-308
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Tidskriftsartikel (refereegranskat)abstract
- The enzyme phenoloxidase (PO) is one of the first immune molecules that was identified in invertebrates. Recently, the immune function of PO has been challenged. We tested how PO is activated following injury in 2 insects, i.e. the fruit fly Drosophila melanogaster and the wax moth Galleria mellonella. Rapid PO activation in Drosophila was limited to discrete areas of the hemolymph clot which forms after injury. Surprisingly, unlike systemic PO activation during bacterial sepsis, clot melanization was not sensitive to microbial elicitors in our assay. Instead, Drosophila clot melanization was activated by endogenous signals such as apoptotic cells and was superinduced by phosphatidylserine, a negatively charged phospholipid normally found on the inner surface of the plasma membrane and exposed during apoptosis. In contrast, melanization in G. mellonella hemolymph was stronger and more uniform and was sensitive to peptidoglycan. This shows that both exogenous and endogenous signals can trigger the same immune mechanism in species and context-dependent ways. Our findings have implications for the evolutionary dynamics of immune mechanisms and are in agreement with recent comparisons of insect immune transcriptomes.
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| 10. |
- Björkbacka, Harry, et al.
(författare)
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Innate immunity in atherosclerosis
- 2010
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 2:4, s. 305-306
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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