| 1. |
- Benedict, Christian, et al.
(författare)
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Acute sleep deprivation increases serum levels of neuron-specific enolase (NSE) and S100 calcium binding protein B (S-100B) in healthy young men.
- 2014
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Ingår i: Sleep. - : Oxford University Press (OUP). - 1550-9109 .- 0161-8105. ; 37:1, s. 195-8
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Tidskriftsartikel (refereegranskat)abstract
- To investigate whether total sleep deprivation (TSD) affects circulating concentrations of neuron-specific enolase (NSE) and S100 calcium binding protein B (S-100B) in humans. These factors are usually found in the cytoplasm of neurons and glia cells. Increasing concentrations of these factors in blood may be therefore indicative for either neuronal damage, impaired blood brain barrier function, or both. In addition, amyloid β (Aβ) peptides 1-42 and 1-40 were measured in plasma to calculate their ratio. A reduced plasma ratio of Aβ peptides 1-42 to 1-40 is considered an indirect measure of increased deposition of Aβ 1-42 peptide in the brain.
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| 2. |
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| 3. |
- Christoffersson, Gustaf, et al.
(författare)
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Acute sleep deprivation in healthy young men : Impact on population diversity and function of circulating neutrophils
- 2014
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Ingår i: Brain, behavior, and immunity. - : Elsevier BV. - 0889-1591 .- 1090-2139. ; 41, s. 162-172
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Tidskriftsartikel (refereegranskat)abstract
- Lack of sleep greatly affects our immune system. The present study investigates the acute effects of total sleep deprivation on blood neutrophils, the most abundant immune cell in our circulation and the first cell type recruited to sites of infection. Thus, the population diversity and function of circulating neutrophils were compared in healthy young men following one night of total sleep deprivation (TSD) or after 8 h regular sleep. We found that neutrophil counts were elevated after nocturnal wakefulness (2.0 +/- 0.2 x 10(9)/l vs. 2.6 +/- 0.2 x 10(9)/l, sleep vs. TSD, respectively) and the population contained more immature CD16(dim)/CD62L(bright) cells (0.11 +/- 0.040 x 10(9)/l [5.5 +/- 1.1%] vs. 0.26 +/- 0.020 x 10(9)/l [9.9 +/- 1.4%]). As the rise in numbers of circulating mature CD16(bright)/CD62L(bright) neutrophils was less pronounced, the fraction of this subpopulation showed a significant decrease (1.8 +/- 0.15 x 10(9)/l [88 +/- 1.8%] vs. 2.1 +/- 0.12 x 10(9)/l [82 +/- 2.8%]). The surface expression of receptors regulating mobilization of neutrophils from bone marrow was decreased (CXCR4 and CD49d on immature neutrophils; CXCR2 on mature neutrophils). The receptor CXCR2 is also involved in the production of reactive oxygen species (ROS), and in line with this, total neutrophils produced less ROS. In addition, following sleep loss, circulating neutrophils exhibited enhanced surface levels of CD11b, which indicates enhanced granular fusion and concomitant protein translocation to the membrane. Our findings demonstrate that sleep loss exerts significant effects on population diversity and function of circulating neutrophils in healthy men. To which extent these changes could explain as to why people with poor sleep patterns are more susceptible to infections warrants further investigation.
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| 4. |
- Christoffersson, Gustaf, et al.
(författare)
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VEGF-A recruits a proangiogenic MMP-9-delivering neutrophil subset that induces angiogenesis in transplanted hypoxic tissue
- 2012
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 120:23, s. 4653-4662
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Tidskriftsartikel (refereegranskat)abstract
- Recruitment and retention of leukocytes at a site of blood vessel growth are crucial for proper angiogenesis and subsequent tissue perfusion. Although critical for many aspects of regenerative medicine, the mechanisms of leukocyte recruitment to and actions at sites of angiogenesis are not fully understood. In this study, we investigated the signals attracting leukocytes to avascular transplanted pancreatic islets and leukocyte actions at the engraftment site. Expression of the angiogenic stimulus VEGF-A by mouse pancreatic islets was elevated shortly after syngeneic transplantation to muscle. High levels of leukocytes, predominantly CD11b+/Gr-1+/CXCR4hi neutrophils, were observed at the site of engraftment, whereas VEGF-A–deficient islets recruited only half of the amount of leukocytes when transplanted. Acute VEGF-A exposure of muscle increased leukocyte extravasation but not the levels of SDF-1α. VEGF-A–recruited neutrophils expressed 10 times higher amounts of MMP-9 than neutrophils recruited to an inflammatory stimulus. Revascularization of islets transplanted to MMP-9–deficient mice was impaired because blood vessels initially failed to penetrate grafts, and after 2 weeks vascularity was still disturbed. This study demonstrates that VEGF-A recruits a proangiogenic circulating subset of CD11b+/Gr-1+ neutrophils that are CXCR4hi and deliver large amounts of the effector protein MMP-9, required for islet revascularization and functional integration after transplantation.
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| 5. |
- Dieterich, Lothar C., et al.
(författare)
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alpha B-crystallin/HspB5 regulates endothelial-leukocyte interactions by enhancing NF-kappa B-induced up-regulation of adhesion molecules ICAM-1, VCAM-1 and E-selectin
- 2013
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Ingår i: Angiogenesis. - : Springer Science and Business Media LLC. - 0969-6970 .- 1573-7209. ; 16:4, s. 975-983
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Tidskriftsartikel (refereegranskat)abstract
- alpha B-crystallin is a small heat shock protein, which has pro-angiogenic properties by increasing survival of endothelial cells and secretion of vascular endothelial growth factor A. Here we demonstrate an additional role of alpha B-crystallin in regulating vascular function, through enhancing tumor necrosis factor alpha (TNF-alpha) induced expression of endothelial adhesion molecules involved in leukocyte recruitment. Ectopic expression of alpha B-crystallin in endothelial cells increases the level of E-selectin expression in response to TNF-alpha, and enhances leukocyte-endothelial interaction in vitro. Conversely, TNF-alpha-induced expression of intercellular adhesion molecule 1, vascular cell adhesion molecule 1 and E-selectin is markedly inhibited in endothelial cells isolated from alpha B-crystallin-deficient mice. This is associated with elevated levels of I kappa B in alpha B-crystallin deficient cells and incomplete degradation upon TNF-alpha stimulation. Consistent with this, endothelial adhesion molecule expression is reduced in inflamed vessels of alpha B-crystallin deficient mice, and leukocyte rolling velocity is increased. Our data identify alpha B-crystallin as a new regulator of leukocyte recruitment, by enhancing pro-inflammatory nuclear factor kappa B-signaling and endothelial adhesion molecule expression during endothelial activation.
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| 8. |
- Jädert, Cecilia, et al.
(författare)
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Decreased leukocyte recruitment by inorganic nitrate and nitrite in microvascular inflammation and NSAID-induced intestinal injury
- 2012
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Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 52:3, s. 683-692
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Tidskriftsartikel (refereegranskat)abstract
- Nitric oxide (NO) generated by vascular NO synthases can exert anti-inflammatory effects, partly through its ability to decrease leukocyte recruitment. Inorganic nitrate and nitrite, from endogenous or dietary sources, have emerged as alternative substrates for NO formation in mammals. Bioactivation of nitrate is believed to require initial reduction to nitrite by oral commensal bacteria. Here we investigated the effects of inorganic nitrate and nitrite on leukocyte recruitment in microvascular inflammation and in NSAID-induced small-intestinal injury. We show that leukocyte emigration in response to the proinflammatory chemokine MIP-2 is reduced by 70% after 7 days of dietary nitrate supplementation as well as by acute intravenous nitrite administration. Nitrite also reduced leukocyte adhesion to a similar extent and this effect was inhibited by the soluble guanylyl cyclase inhibitor ODQ whereas the effect on emigrated leukocytes was not altered by this treatment. Further studies in INF-alpha-stimulated endothelial cells revealed that nitrite dose-dependently reduced the expression of ICAM-1. In rats and mice subjected to a challenge with diclofenac, dietary nitrate prevented the increase in myeloperoxidase and P-selectin levels in small-intestinal tissue. Antiseptic mouthwash, which eliminates oral nitrate reduction, markedly blunted the protective effect of dietary nitrate on P-selectin levels. Despite attenuation of the acute immune response, the overall ability to clear an infection with Staphylococcus aureus was not suppressed by dietary nitrate as revealed by noninvasive IVIS imaging. We conclude that dietary nitrate markedly reduces leukocyte recruitment to inflammation in a process involving attenuation of P-selectin and ICAM-1 upregulation. Bioactivation of dietary nitrate requires intermediate formation of nitrite by oral nitrate-reducing bacteria and then probably further reduction to NO and other bioactive nitrogen oxides in the tissues.
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| 9. |
- Massena, Sara, et al.
(författare)
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A chemotactic gradient sequestered on endothelial heparan sulfate induces directional intraluminal crawling of neutrophils
- 2010
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 116:11, s. 1924-1931
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Tidskriftsartikel (refereegranskat)abstract
- During infection, chemokines sequestered on endothelium induce recruitment of circulating leukocytes into the tissue where they chemotax along chemokine gradients toward the afflicted site. The aim of this in vivo study was to determine whether a chemokine gradient was formed intravascularly and influenced intraluminal neutrophil crawling and transmigration. A chemokine gradient was induced by placing a macrophage inflammatory protein-2 (MIP-2)-containing (CXCL2) gel on the cremaster muscle of anesthetized wild-type mice or heparanase-overexpressing transgenic mice (hpa-tg) with truncated heparan sulfate (HS) side chains. Neutrophil-endothelial interactions were visualized by intravital microscopy and chemokine gradients detected by confocal microscopy. Localized extravascular chemokine release (MIP-2 gel) induced directed neutrophil crawling along a chemotactic gradient immobilized on the endothelium and accelerated their recruitment into the target tissue compared with homogeneous extravascular chemokine concentration (MIP-2 super-fusion). Endothelial chemokine sequestration occurred exclusively in venules and was HS-dependent, and neutrophils in hpa-tg mice exhibited random crawling. Despite similar numbers of adherent neutrophils in hpa-tg and wild-type mice, the altered crawling in hpa-tg mice was translated into decreased number of emigrated neutrophils and ultimately decreased the ability to clear bacterial infections. In conclusion, an intravascular chemokine gradient sequestered by endothelial HS effectively directs crawling leukocytes toward transmigration loci close to the infection site.
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| 10. |
- Massena, Sara
(författare)
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A close-up on neutrophils : Visualizing the mechanisms of their in vivo recruitment and function
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A successful immune response depends on prompt and sufficient recruitment of leukocytes from the circulation to infected or injured sites. Mobilization of leukocytes to hypoxic tissues is vital for angiogenesis, i.e. the formation of new blood vessels from preexisting vasculature, and thus crucial for tissue growth and regeneration. Deviations from normal leukocyte recruitment drive a variety of pathologies, including chronic inflammation, autoimmune diseases and cancer, for which therapeutic options are limited or unspecific. Understanding the mechanisms by which the body controls leukocyte recruitment is therefore critical for the development of novel therapeutic strategies.The present investigations focused on delineating the mechanisms behind leukocyte mobilization from the bloodstream to afflicted sites, by means of in vivo imaging techniques and in vitro assays. We demonstrate that, in response to inflammation, increased vascular permeability enhances transendothelial transport of tissue-released chemokines. Within the vasculature, chemokines form a chemotactic gradient sequestered on heparan sulfate, which directs crawling neutrophils and expedites their extravasation to the inflamed tissue. Consequently, gradient formation grants efficient bacterial clearance. Citrullination of chemokines by leukocyte-derived PAD enzymes in the inflamed tissue prevents chemokine transport into blood vessels, which dampens further neutrophil recruitment and thereby controls the amplitude of the inflammatory response. Moreover, the mechanisms of neutrophil recruitment in response to proangiogenic factors released during hypoxia are revealed to differ from those observed during classical inflammation. Particularly, VLA-4 integrin and VEGFR1 expressed on a defined subset of neutrophils, along with endothelial VEGFR2, are required for efficient neutrophil recruitment to hypoxia. Rather than stimulus-induced phenotypic changes on neutrophils, specific neutrophil subtypes with innate proinflammatory or proangiogenic functions (respectively, CD49d-VEGFR1lowCXCR4low and CD49d+VEGFR1highCXCR4high) coexist in the circulation of humans and mice.In summary, this dissertation provides relevant information on specific steps of neutrophil recruitment to inflamed or hypoxic tissues, which may represent future means to down-regulate aberrant immune responses during chronic inflammation and autoimmune diseases; to increase angiogenesis during ischemia; or to limit pathological angiogenesis, a characteristic of tumor growth and of several chronic inflammatory disorders.
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