| 1. |
- Boldock, Emma, et al.
(författare)
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Human skin commensals augment Staphylococcus aureus pathogenesis.
- 2018
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Ingår i: Nature microbiology. - : Springer Science and Business Media LLC. - 2058-5276. ; 3:8, s. 881-90
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Tidskriftsartikel (refereegranskat)abstract
- All bacterial infections occur within a polymicrobial environment, from which a pathogen population emerges to establish disease within a host. Emphasis has been placed on prevention of pathogen dominance by competing microflora acting as probiotics1. Here we show that the virulence of the human pathogen Staphylococcus aureus is augmented by native, polymicrobial, commensal skin flora and individual species acting as 'proinfectious agents'. The outcome is pathogen proliferation, but not commensal. Pathogenesis augmentation can be mediated by particulate cell wall peptidoglycan, reducing the S. aureus infectious dose by over 1,000-fold. This phenomenon occurs using a range of S. aureus strains and infection models and is not mediated by established receptor-mediated pathways including Nod1, Nod2, Myd88 and the NLPR3 inflammasome. During mouse sepsis, augmentation depends on liver-resident macrophages (Kupffer cells) that capture and internalize both the pathogen and the proinfectious agent, leading to reduced production of reactive oxygen species, pathogen survival and subsequent multiple liver abscess formation. The augmented infection model more closely resembles the natural situation and establishes the role of resident environmental microflora in the initiation of disease by an invading pathogen. As the human microflora is ubiquitous2, its role in increasing susceptibility to infection by S. aureus highlights potential strategies for disease prevention.
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| 2. |
- Audoy-Remus, Julie, et al.
(författare)
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Rod-Shaped Monocytes Patrol the Brain Vasculature and Give Rise to Perivascular Macrophages under the Influence of Proinflammatory Cytokines and Angiopoietin-2
- 2008
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 28:41, s. 10187-10199
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Tidskriftsartikel (refereegranskat)abstract
- The nervous system is constantly infiltrated by blood-derived sentinels known as perivascular macrophages. Their immediate precursors have not yet been identified in situ and the mechanism that governs their recruitment is mostly unknown. Here, we provide evidence that CD68 (+)GR(-) monocytes can give rise to perivascular macrophages in mice suffering from endotoxemia. After adhesion to the endothelium, these monocytes start to crawl, adopt a rod-shaped morphology when passing through capillaries, and can manifest the ability to proliferate and form a long cytoplasmic protuberance. They are attracted in greater numbers during endotoxemia by a combination of vasoregulatory molecules, including TNF (tumor necrosis factor), interleukin-1 beta, and angiopoietin-2. After a period of several hours, some of them cross the endothelium to expand the population of perivascular macrophages. Depletion of adherent monocytes and perivascular macrophages can be achieved by injection of anti-angiopoietin-2 peptide-Fc fusion protein. This study extends our understanding of the behavior of monocytes at the blood-brain interface and provides a way to block their infiltration into the nervous tissue under inflammatory conditions.
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| 3. |
- Li, Sandra, et al.
(författare)
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Interference with Glycosaminoglycan-Chemokine Interactions with a Probe to Alter Leukocyte Recruitment and Inflammation In Vivo
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:8, s. e104107-
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Tidskriftsartikel (refereegranskat)abstract
- In vivo leukocyte recruitment is not fully understood and may result from interactions of chemokines with glycosaminoglycans/GAGs. We previously showed that chlorite-oxidized oxyamylose/COAM binds the neutrophil chemokine GCP-2/CXCL6. Here, mouse chemokine binding by COAM was studied systematically and binding affinities of chemokines to COAM versus GAGs were compared. COAM and heparan sulphate bound the mouse CXC chemokines KC/CXCL1, MIP-2/CXCL2, IP-10/CXCL10 and I-TAC/CXCL11 and the CC chemokine RANTES/CCL5 with affinities in the nanomolar range, whereas no binding interactions were observed for mouse MCP-1/CCL2, MIP-1 alpha/CCL3 and MIP-1 beta/CCL4. The affinities of COAM-interacting chemokines were similar to or higher than those observed for heparan sulphate. Although COAM did not display chemotactic activity by itself, its co-administration with mouse GCP-2/CXCL6 and MIP-2/CXCL2 or its binding of endogenous chemokines resulted in fast and cooperative peritoneal neutrophil recruitment and in extravasation into the cremaster muscle in vivo. These local GAG mimetic features by COAM within tissues superseded systemic effects and were sufficient and applicable to reduce LPS-induced liver-specific neutrophil recruitment and activation. COAM mimics glycosaminoglycans and is a nontoxic probe for the study of leukocyte recruitment and inflammation in vivo.
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| 4. |
- Nordling, Sofia, 1985-
(författare)
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Vascular Interactions in Innate Immunity and Immunothrombosis: : Models of Endothelial Protection
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The phenomenon known as immunothrombosis has garnered increased attention over the last few years. Much work has been done to characterize the cross talk between hemostasis and the innate immune system. This thesis outlines the role of the vascular endothelial cells during immunothrombotic events as regulators of coagulation, platelet-, and leukocyte recruitment.A newly developed method for investigating the interaction between endothelial cells and the blood compartment illustrated the procoagulant and proinflammatory effects elicited by tumor necrosis factor α activated endothelial cells upon exposure to whole blood. The method was utilized in evaluating treatment of endothelial dysfunction and disruption with a heparin conjugate. Damaged or hypoxic endothelial cells, in addition to basement membrane collagen, that were pretreated with the heparin conjugate prior to contact with blood were found to have reduced activation of coagulation, platelet-, and leukocyte recruitment; in contrast to unfractionated heparin, which had no effect on the aforementioned parameters. The treatment was then investigated in the setting of ischemia reperfusion injury during kidney transplantation and the heparin conjugate was found to bind cultured endothelial cells with high avidity under cold storage conditions. Furthermore, it was found to bind to the renal vasculature during static cold storage and was subsequently found to be beneficial with regard to early graft function in an experimental mouse model of syngeneic kidney transplantation. Recipients of kidneys treated with the heparin conjugate had reduced serum creatinine compared to controls 24 hours after transplantation. Lastly, the anticoagulant properties of the heparin conjugate were investigated in comparison to unfractionated heparin. While the conjugate exerted reduced capacity with regard to thrombin inhibition, it rapidly inhibited the binding of platelets to exposed collagen. The conjugate was furthermore found to preferentially locate to sites of endothelial cell activation at early stage during endotoxic shock in mice.In conclusion, this thesis demonstrates that disrupted functioning of the vascular endothelial cells actively contributes to immunothrombosis, and that it is possible to model endothelial cell function using whole blood assays. Furthermore, this thesis presents a treatment that enhances the hemocompatibility of damaged endothelial cells and subsequently improves the early renal function after kidney transplantation.
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| 5. |
- Petri, Björn, et al.
(författare)
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Endothelial LSP1 is involved in endothelial dome formation, minimizing vascular permeability changes during neutrophil transmigration in vivo
- 2011
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 117:3, s. 942-952
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Tidskriftsartikel (refereegranskat)abstract
- The endothelium actively participates in neutrophil migration out of the vasculature via dynamic, cytoskeleton-dependent rearrangements leading to the formation of transmigratory cups in vitro, and to domes that completely surround the leukocyte in vivo. Leukocyte-specific protein 1 (LSP1), an F-actin-binding protein recently shown to be in the endothelium, is critical for effective transmigration, although the mechanism has remained elusive. Herein we show that endothelial LSP1 is expressed in the nucleus and cytosol of resting endothelial cells and associates with the cytoskeleton upon endothelial activation. Two-photon microscopy revealed that endothelial LSP1 was crucial for the formation of endothelial domes in vivo in response to neutrophil chemokine keratinocyte-derived chemokine (KC) as well as in response to endogenously produced chemokines stimulated by cytokines (tumor necrosis factor α [TNFα] or interleukin-1β [IL-1β]). Endothelial domes were significantly reduced in Lsp1-/- compared with wildtype (WT) mice. Lsp1-/- animals not only showed impaired neutrophil emigration after KC and TNFα stimulation, but also had disproportionate increases in vascular permeability. We demonstrate that endothelial LSP1 is recruited to the cytoskeleton in inflammation and plays an important role in forming endothelial domes thereby regulating neutrophil transendothelial migration. The permeability data may underscore the physiologic relevance of domes and the role for LSP1 in endothelial barrier integrity.
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| 6. |
- Petri, Björn, et al.
(författare)
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The physiology of leukocyte recruitment : an in vivo perspective
- 2008
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Ingår i: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 180:10, s. 6439-6446
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Forskningsöversikt (refereegranskat)abstract
- The mechanisms of leukocyte recruitment have been studied extensively in vitro and have shed light on the basic molecular structure-function relationship of adhesion and signaling molecules involved in this essential immune response. This review will summarize how these in vitro observations extend to leukocyte behavior in inflamed blood vessels in the microcirculation. We highlight physiological results that might not have been predicted from in vitro systems. Special attention is placed on the physiology of rolling, adhesion, and intralumenal crawling in blood vessels. The importance of the glycocalyx, secondary tethers, shear, and the microenvironment are discussed. Docking structures forming rings of adhesion molecules together with a novel endothelial dome-like structure in vivo during transmigration are highlighted. Transcellular and paracellular emigration out of inflamed blood vessels is also discussed. The last section highlights leukocyte recruitment in some organs that do not always follow the accepted paradigm of leukocyte recruitment.
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| 7. |
- Phillipson, Mia, et al.
(författare)
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Endothelial domes encapsulate adherent neutrophils and minimize increases in vascular permeability in paracellular and transcellular emigration
- 2008
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 3:2, s. e1649-
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Tidskriftsartikel (refereegranskat)abstract
- Local edema, a cardinal sign of inflammation associates closely with neutrophil emigration. Neutrophil emigration has been described to occur primarily through endothelial junctions (paracellular) and more rarely directly through endothelial cells (transcellular). Recently, we reported that unlike in wild-type (wt) mice, Mac-1-/- (CD11b) neutrophils predominantly emigrated transcellularly and was significantly delayed taking 20-30 min longer than the paracellular emigration (wt). In the present study we noted significant anatomical disruption of the endothelium and hypothesized that transcellular emigration would greatly increase vascular permeability. Surprisingly, despite profound disruption of the endothelial barrier as the neutrophils moved through the cells, the changes in vascular permeability during transcellular emigration (Mac-1-/-) were not increased more than in wt mice. Instead increased vascular permeability completely tracked the number of emigrated cells and as such, permeability changes were delayed in Mac-1-/- mice. However, by 60 min neutrophils from both sets of mice were emigrating in large numbers. Electron-microscopy and spinning disk multichannel fluorescence confocal microscopy revealed endothelial docking structures that progressed to dome-like structures completely covering wt and Mac-1-/- neutrophils. These domes completely enveloped the emigrating neutrophils in both wt and Mac-1-/- mice making the mode of emigration underneath these structures extraneous to barrier function. In conclusion, predominantly paracellular versus predominantly transcellular emigration does not affect vascular barrier integrity as endothelial dome-like structures retain barrier function.
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| 8. |
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| 9. |
- Phillipson, Mia, 1973-, et al.
(författare)
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The Healing Power of Neutrophils
- 2019
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Ingår i: Trends in immunology. - : Elsevier. - 1471-4906 .- 1471-4981. ; 40:7, s. 635-647
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Forskningsöversikt (refereegranskat)abstract
- Neutrophils promptly accumulate in large numbers at sites of tissue injury. Injuries to the skin or mucosae disrupt barriers against the external environment, and the bactericidal actions of neutrophils are important in preventing microbial invasion. Neutrophils have also been associated with exacerbated inflammation, for example in non-healing wounds or in conditions such as inflammatory bowel disease (IBD). However, additional neutrophil functions important for angiogenesis and tissue restoration have been uncovered in models of sterile and ischemic injury, as well as in tumors. These functions are also relevant in healing skin and mucosal wounds, and can be impaired in conditions associated with non-healing wounds, such as diabetes. Here, we discuss our current understanding of neutrophil contributions to healing, and how the latter can be compromised in disease.
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| 10. |
- Phillipson, Mia, et al.
(författare)
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The neutrophil in vascular inflammation
- 2011
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 17:11, s. 1381-1390
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Forskningsöversikt (refereegranskat)abstract
- Here we focus on how neutrophils have a key regulatory role in vascular inflammation. Recent studies using advanced imaging techniques have yielded new insights into the mechanisms by which neutrophils contribute to defense against bacterial infections and also against sterile injury. In these settings, neutrophils are recruited by various mechanisms depending on the situation. We also describe how these processes may be disrupted in systemic infections, with a particular emphasis on mouse models of sepsis. Neutrophils are often immobilized in the lungs and liver during systemic infections, and this immobilization may be a mechanism through which bacteria can evade the innate immune response or allow neutrophils to form neutrophil extracellular traps that trap and kill bacteria in blood. The platelet is also an important player in sepsis, and we describe how it collaborates with neutrophils in the formation of neutrophil extracellular traps.
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