| 1. |
- Abdulla, Aree, et al.
(författare)
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Role of neutrophils in the activation of trypsinogen in severe acute pancreatitis.
- 2011
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 90, s. 975-982
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between inflammation and proteolytic activation in pancreatitis is an unresolved issue in pancreatology. The purpose of this study was to define the influence of neutrophils on trypsinogen activation in severe AP. Pancreatitis was induced by infusion of taurocholate into the pancreatic duct in C57BL/6 mice. For neutrophil depletion, an anti-Gr-1 antibody was administered before pancreatitis induction. Administration of the anti-Gr-1 antibody reduced circulating neutrophils by 97%. Pancreatic TAP and serum amylase levels increased 2 h and 24 h after induction of pancreatitis. Neutrophil depletion reduced pancreatic TAP and serum amylase levels at 24 h but not at 2 h after pancreatitis induction. Pancreatic MPO and infiltration of neutrophils, as well as MIP-2 levels, were increased 24 h after taurocholate infusion. Two hours after taurocholate administration, no significant pancreatic infiltration of neutrophils was observed. Injection of the anti-Gr-1 antibody abolished MPO activity, neutrophil accumulation, and MIP-2 levels, as well as acinar cell necrosis, hemorrhage, and edema in the pancreas at 24 h. Moreover, taurocholate-provoked tissue damage and MPO activity in the lung were normalized by neutrophil depletion. Intravital fluorescence microscopy revealed a 97% reduction of leukocytes in the pancreatic microcirculation after administration of the anti-Gr-1 antibody. Our data demonstrate that initial trypsinogen activation is independent of neutrophils, whereas later activation is dependent on neutrophils in the pancreas. Neutrophils are critical in mediating pancreatic and lung tissue damage in severe AP.
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| 2. |
- Andersson, A, et al.
(författare)
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Differential macrophage expression of IL-12 and IL-23 upon innate immune activation defines rat autoimmune susceptibility
- 2004
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 76:6, s. 1118-1124
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Tidskriftsartikel (refereegranskat)abstract
- Rodents typically demonstrate strain-specific susceptibilities to induced autoimmune models such as experimental arthritis and encephalomyelitis. A common feature of the local pathology of these diseases is an extensive infiltration of activated macrophages (MΦ). Different functional activation states can be induced in MΦ during innate immune activation, and it is this differential activation that might be important in susceptibility/resistance to induction or perpetuation of autoimmunity. In this study, we present an extensive, comparative analysis of the activation phenotypes of MΦ derived from autoimmune-susceptible and autoimmune-resistant rat strains to describe a cellular phenotype that defines the disease phenotype. We included investigation of receptor function, intracellular signaling pathways, cytokines, and other soluble mediators released after activation of cells using a panel of stimuli embracing many activation routes. We report that activation of MΦ from the autoimmune-susceptible strain was associated with alternative activation indicated by induction of arginase activity, a lower production of classical proinflammatory mediators, and a high production of interleukin (IL)-23, and MΦ from the autoimmune-resistant strains were associated with a higher production of proinflammatory mediators, a classical activation phenotype, and preferential induction of IL-12. These MΦ phenotypes thus reflect disparate, genetic cellular programs that define autoimmune susceptibility.
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| 3. |
- Andersson, Åsa, et al.
(författare)
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Pivotal Advance : HMGB1 expression in active lesions of human and experimental multiple sclerosis
- 2008
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 84:5, s. 1248-1255
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Forskningsöversikt (refereegranskat)abstract
- Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating disease of the CNS, most frequently starting with a series of bouts, each followed by complete remission and then a secondary, progressive phase during which the neurological deficit increases steadily. The underlying molecular mechanisms responsible for disease progression are still unclear. Herein, we demonstrate that high mobility group box chromosomal protein 1 (HMGB1), a DNA-binding protein with proinflammatory properties, is evident in active lesions of MS and experimental autoimmune encephalomyelitis (EAE) and that HMGB1 levels correlate with active inflammation. Furthermore, the expression of the innate HMGB1 receptors--receptor for advanced glycation end products, TLR2, and TLR4--was also highly increased in MS and rodent EAE. Additionally, in vitro activation of rodent CNS-derived microglia and bone marrow-derived macrophages demonstrated that microglia were equally as capable as macrophages of translocating HMGB1 following LPS/IFN-gamma stimulation. Significant expression of HMGB1 and its receptors on accumulating activated macrophages and resident microglia may thus provide a positive feedback loop that amplifies the inflammatory response during MS and EAE pathogenesis.
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| 4. |
- Asplund, Annika, 1979, et al.
(författare)
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Hypoxia increases macrophage motility, possibly by decreasing the heparan sulfate proteoglycan biosynthesis.
- 2009
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 86:2, s. 381-8
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Tidskriftsartikel (refereegranskat)abstract
- Macrophages are recruited and retained in hypoxic sites in atherosclerotic lesions and tumors. Furthermore, macrophages are suggested to be a major source of HSPG synthesis in atherosclerotic lesions. HSPG are, among other things, known to regulate cell motility, cell adhesion, and receptor interaction. The aim of this study was to investigate the effect of hypoxia on HSPG expression and macrophage motility. We also explored the potential regulation of HSPG by the transcription factor HIF-1alpha. The nondirected cell motility was increased in HMDM after 24 h exposure to hypoxia (0.5% O(2)) compared with normal cell culture condition (21% O(2)). Enzymatic degradation of HS GAG further increased the motility of the HMDM in hypoxia, indicating a role of reduced cell-associated HSPG in the increased HMDM motility. HMDM exposed to 24 h of hypoxia had lower mRNA expressions of syndecan-1 and -4 compared with cells exposed to normal cell culture conditions. Protein levels of syndecan-1 were also decreased significantly in response to hypoxia, and cells subjected to hypoxia had lower mRNA expression for key enzymes involved in HS biosynthesis. In addition, hypoxia was found to reduce the relative content of HS GAG. Transfecting THP-1 cells with siHIF-1alpha indicated that this transcription factor was not involved in the hypoxia-induced modifications of HSPG expression. Given the documented multiple functions of HSPG in macrophage behavior, the hypoxia-induced modifications of HSPG may be of relevance for the development of atherosclerotic lesions and tumor progression.
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| 5. |
- Aurelius, Johan, 1980, et al.
(författare)
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Chronic myeloid leukemic cells trigger poly(ADP-ribose) polymerase-dependent inactivation and cell death in lymphocytes.
- 2013
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 93:1, s. 155-160
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Tidskriftsartikel (refereegranskat)abstract
- NK cells and T cells are commonly dysfunctional in CML, and their status may determine the course of disease. We aimed to define the molecular mechanisms of leukemia-induced immunosuppression with focus on the role of ROS and the PARP-1 pathway of cell death. Malignant granulocytes from patients with BCR-ABL-positive CML expressed the oxygen radical-producing enzyme NOX, produced large amounts of ROS, and triggered extensive cell death in NK cells. Inhibition of PARP-1 maintained NK cell viability in cocultures with suppressive leukemic cells. Under conditions of oxidative stress, PARP-1 inhibition upheld the capacity of NK cells to kill myeloid leukemic cells, in addition to restoring the proliferation and cytokine production of NK cells and cytotoxic T cells. Our findings are suggestive of a novel pathway of relevance to immunosuppression in CML.
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| 6. |
- Aurelius, Johan, 1980, et al.
(författare)
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NOX2-dependent immunosuppression in chronic myelomonocytic leukemia
- 2017
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Ingår i: Journal of Leukocyte Biology. - 0741-5400 .- 1938-3673. ; 102:2, s. 459-466
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Tidskriftsartikel (refereegranskat)abstract
- Chronic myelomonocytic leukemia (CMML) is a myeloproliferative and myelodysplastic neoplasm with few treatment options and dismal prognosis. The role of natural killer (NK) cells and other antileukemic lymphocytes in CMML is largely unknown. We aimed to provide insight into the mechanisms of immune evasion in CMML with a focus on immunosuppressive reactive oxygen species (ROS) formed by the myeloid cell NADPH oxidase-2 (NOX2). The dominant population of primary human CMML cells was found to express membrane-bound NOX2 and to release ROS, which, in turn, triggered extensive PARP-1-dependent cell death in cocultured NK cells, CD8(+) T effector memory cells, and CD8(+) T effector cells. Inhibitors of ROS formation and scavengers of extracellular ROS prevented CMML cell-induced lymphocyte death and facilitated NK cell degranulation toward Ab-coated, primary CMML cells. In patients with CMML, elevation of immature cell counts (CD34(+)) in blood was associated with reduced expression of several NK cell-activating receptors. We propose that CMML cells may use extracellular ROS as a targetable mechanism of immune escape.
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| 7. |
- Awla, Darbaz, et al.
(författare)
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Neutrophil-derived matrix metalloproteinase-9 is a potent activator of trypsinogen in acinar cells in acute pancreatitis.
- 2012
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 91, s. 711-719
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Tidskriftsartikel (refereegranskat)abstract
- MMPs are generally considered to regulate degradation and remodeling of the ECM. Convincing data also implicate a role for MMPs in inflammatory conditions, such as AP, although the mechanisms are not known. The aim of this study was to define the role of MMPs in regulating activation of trypsinogen and tissue damage in AP, which was induced by infusion of taurocholate into the pancreatic duct in mice. A broad-spectrum MMP inhibitor (BB-94) and MMP-9 gene-deficient mice were used. Neutrophil secretions and rMMP-9 were used to stimulate trypsinogen activation in isolated acinar cells. Taurocholate challenge increased serum amylase, neutrophil infiltration, MIP-2 (CXCL2) formation, trypsinogen activation, and tissue damage in the pancreas. Treatment with the broad-spectrum inhibitor of MMPs, BB-94, markedly reduced activation of trypsinogen, levels of CXCL2, infiltration of neutrophils, and tissue damage in AP. Taurocholate challenge increased serum levels of MMP-9 but not MMP-2. Taurocholate-induced amylase levels, neutrophil accumulation, production of CXCL2, trypsinogen activation, and tissue damage in the pancreas were abolished in MMP-9-deficient mice. Moreover, secretions from activated neutrophils isolated from WT but not from MMP-9-deficient animals stimulated trypsinogen activation in acinar cells. Notably, rMMP-9 greatly enhanced activation of trypsinogen in acinar cells. These findings demonstrate that neutrophil-derived MMP-9 is a potent activator of trypsinogen in acinar cells and regulates pathological inflammation and tissue damage in AP.
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| 8. |
- Barratt-Due, Andreas, et al.
(författare)
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Dual inhibition of complement and Toll-like receptors as a novel approach to treat inflammatory diseases-C3 or C5 emerge together with CD14 as promising targets.
- 2017
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Ingår i: Journal of Leukocyte Biology. - 0741-5400 .- 1938-3673. ; 101:1, s. 193-204
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Tidskriftsartikel (refereegranskat)abstract
- The host is protected by pattern recognition systems, including complement and TLRs, which are closely cross-talking. If improperly activated, these systems might induce tissue damage and disease. Inhibition of single downstream proinflammatory cytokines, such as TNF, IL-1β, and IL-6, have failed in clinical sepsis trials, which might not be unexpected, given the substantial amounts of mediators involved in the pathogenesis of this condition. Instead, we have put forward a hypothesis of inhibition at the recognition phase by "dual blockade" of bottleneck molecules of complement and TLRs. By acting upstream and broadly, the dual blockade could be beneficial in conditions with improper or uncontrolled innate immune activation threatening the host. Key bottleneck molecules in these systems that could be targets for inhibition are the central complement molecules C3 and C5 and the important CD14 molecule, which is a coreceptor for several TLRs, including TLR4 and TLR2. This review summarizes current knowledge of inhibition of complement and TLRs alone and in combination, in both sterile and nonsterile inflammatory processes, where activation of these systems is of crucial importance for tissue damage and disease. Thus, dual blockade might provide a general, broad-acting therapeutic regimen against a number of diseases where innate immunity is improperly activated.
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| 9. |
- Bauer, Susanne, et al.
(författare)
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Membrane retrieval in neutrophils during phagocytosis: inhibition by M protein-expressing S. pyogenes bacteria.
- 2004
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 76:6, s. 1142-1150
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Tidskriftsartikel (refereegranskat)abstract
- During phagocytosis and phagosome maturation, complex membrane traffic events must be coordinated. We have observed, using fluorescent fluid-phase and membrane markers, that in the human neutrophil, internalization of nonopsonized, Gram-positive bacteria, but not of latex beads, is accompanied by a rapid and localized formation of pinosomal structures. This pinocytic response is calcium-dependent but insensitive to actin cytoskeleton disruption and wortmannin treatment. Contrary to what we observe, endosomal structures usually are considered to participate in phagosome formation by providing necessary membrane to forming phagosomes. Instead, our results show a coupling between neutrophil secretory and membrane-retrieval processes during phagosome maturation, and we suggest that the observed, localized pinocytic response is linked to the secretion of azurophilic granules toward nascent phagosomes. Accordingly, M and M-like protein-expressing Streptococcus pyogenes bacteria, which are able to survive inside neutrophil phagosomes, inhibit both the secretion of azurophilic granules to phagosomes and pinosome formation.
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| 10. |
- Bauer, Susanne, et al.
(författare)
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Proteinase 3 and CD177 are expressed on the plasma membrane of the same subset of neutrophils.
- 2007
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 81, s. 458-464
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Tidskriftsartikel (refereegranskat)abstract
- Proteinase 3 (PR3) is found in granules of all nentrophils but also on the plasma membrane of a subset of nentrophils (mPR3). CD177, another neutrophil protein, also displays a bimodal surface expression. In this study, we have investigated the coexpression of these two molecules, as well as the effect of cell activation on their surface expression. We can show that CD177 is expressed on the same subset of nentrophils as mPR3. Experiments show that the expression of mPR3 and CD177 on the plasma membrane is increased or decreased in parallel during cell stimulation or spontaneous apoptosis. Furthermore, we observed a rapid internalization and recirculation of mPR3 and plasma membrane CD177, where A mPR3 is replaced within 30 min. Our findings suggest that the PR3 found on the plasma membrane has its origin in the same intracellular storage as CD177, i.e., secondary granules and secretory vesicles and not primary granules. PR3- and CD177-expressing neutrophils constitute a subpopulation of neutrophils with an unknown role in the innate immune system, which may play an important role in diseases such as Wegener's granulomatosis and polycythemia vera.
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| 11. |
- Bengtsson, A, et al.
(författare)
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Not only Th2 cells but also Th1 and Th0 cells express CD30 after activation
- 1995
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 58:6, s. 683-689
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Tidskriftsartikel (refereegranskat)abstract
- To investigate whether the CD30 molecule, expressed only by a minority of T and B cells, defines a subtype of T helper cells, Pityrosporum orbiculare-specific CD4+ T cell clones were assessed for CD30 protein and gene expression. The clones were defined as Th1, Th0, and Th2 according to their cytokine mRNA profile detected by reverse transcription PCR (RT-PCR). The kinetics of CD30 expression after OKT3 (anti-CD3) stimulation was analyzed by flow cytometry, immunocytochemistry, and RT-PCR. OKT3 activation induced a high expression of CD30 in cells of both Th1 and Th0 as well as Th2 type after 1-3 days. A difference between the clones was noted in that the Th2 clones remained highly positive in CD30 expression, whereas expression in the other clones started to decline from day 3. These data indicate that CD30 is expressed in activated CD4+ T cells of all three subtypes, and that the expression is sustained in Th2 cells.
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| 12. |
- Bergh Thorén, Fredrik, 1976, et al.
(författare)
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A hepatitis C virus-encoded, nonstructural protein (NS3) triggers dysfunction and apoptosis in lymphocytes: role of NADPH oxidase-derived oxygen radicals
- 2004
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 76:6, s. 1180-6
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Tidskriftsartikel (refereegranskat)abstract
- The persistent infection caused by hepatitis C virus (HCV) is presumably explained by a deficient immune response to the infection, but the basis for the inefficiency of immune-mediated virus eradication is not known in detail. This study addresses mechanisms of relevance to dysfunction of cytotoxic lymphocytes in HCV infection, with a focus on the role of phagocyte-derived oxygen radicals. We show that NS3, a nonstructural, HCV-encoded protein, induces a prolonged release of oxygen radicals from mononuclear and polymorphnuclear phagocytes by activating a key enzyme in radical formation, the reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The NS3-activated phagocytes, in turn, induced dysfunction and/or apoptosis in three major subsets of lymphocytes of relevance to defense against HCV infection: CD3+/56- T cells, CD3-/56+ natural killer (NK) cells, and CD3+/56+ NKT cells. Two inhibitors of the NADPH oxidase, histamine and diphenylene iodonium, suppressed the NS3-induced oxygen radical production and efficiently protected lymphocytes against NS3-induced apoptosis and dysfunction. In conclusion, we propose that NS3, by triggering oxygen radical formation in phagocytes, may contribute to the dysfunction of antiviral lymphocytes in HCV-infected liver tissue and that strategies to circumvent oxidative stress may be useful in preventing HCV-associated carcinogenesis and facilitating lymphocyte-mediated clearance of infected cells.
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| 13. |
- Bhandage, Amol K., et al.
(författare)
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GABAergic signaling in human and murine NK cells upon challenge with Toxoplasma gondii
- 2021
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 110:4, s. 617-628
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Tidskriftsartikel (refereegranskat)abstract
- Protective cytotoxic and proinflammatory cytokine responses by NK cells impact the outcome of infections by Toxoplasma gondii, a common parasite in humans and other vertebrates. However, T. gondii can also sequester within NK cells and downmodulate their effector functions. Recently, the implication of GABA signaling in infection and inflammation-related responses of mononuclear phagocytes and T cells has become evident. Yet, the role of GABAergic signaling in NK cells has remained unknown. Here, we report that human and murine NK cells synthesize and secrete GABA in response to infection challenge. Parasitized NK cells secreted GABA, whereas activation stimuli, such as IL-12/IL-18 or parasite lysates, failed to induce GABA secretion. GABA secretion by NK cells was associated to a transcriptional up-regulation of GABA synthesis enzymes (glutamate decarboxylases [GAD65/67]) and was abrogated by GAD inhibition. Further, NK cells expressed GABA-A receptor subunits and GABA signaling regulators, with transcriptional modulations taking place upon challenge with T. gondii. Exogenous GABA and GABA-containing supernatants from parasitized dendritic cells (DCs) impacted NK cell function by reducing the degranulation and cytotoxicity of NK cells. Conversely, GABA-containing supernatants from NK cells enhanced the migratory responses of parasitized DCs. This enhanced DC migration was abolished by GABA-A receptor antagonism or GAD inhibition and was reconstituted by exogenous GABA. Jointly, the data show that NK cells are GABAergic cells and that GABA hampers NK cell cytotoxicity in vitro. We hypothesize that GABA secreted by parasitized immune cells modulates the immune responses to T. gondii infection.
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| 14. |
- Bjork, L, et al.
(författare)
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Computerized assessment of production of multiple human cytokines at the single-cell level using image analysis
- 1996
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 59:2, s. 287-295
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Tidskriftsartikel (refereegranskat)abstract
- A technique using a computerized image analysis system was developed for evaluating and quantifying human cytokine production. This system registered single cells as positive or negative cytokine producers based on a specific juxtanuclear staining pattern generated by accumulation of the proteins in the Golgi-endoplasmatic reticulum compartment. The characteristic morphology of the immunocytochemical staining offered the opportunity to register individual producer cells within multicomponent cell populations. A color camera was then adapted to transfer on-line images directly into the computer-controlled operating system. In this study cultured human peripheral blood mononuclear cells were polyclonally stimulated and then analyzed for interleukin-1α (IL-1α), IL-1β, IL-1ra, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor-α (TNF-α), TNF-β, interferon-γ, granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor production. The image-analyzing system detected cytokine-producing cells in a sensitive and reproducible manner, which was in total congruence with enumeration by conventional microscopy. Furthermore, accurate assessments of cell distributions by signal intensity and cell area were applied at the single-cell level. The image-analyzing system allowed the detection of at least 1 in 1,000 events by using unique cytokine-associated morphometric criteria. The results of kinetic studies measuring cytokine production following activation and cell transformation provided data supporting increases in intensity of intracellular localized specific immunostaining and in cell size within the cytokine-producing cells.
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| 15. |
- Björkman, Lena, 1965, et al.
(författare)
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Serum amyloid A mediates human neutrophil production of reactive oxygen species through a receptor independent of formyl peptide receptor like-1
- 2008
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 83:2, s. 245-53
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Tidskriftsartikel (refereegranskat)abstract
- Serum amyloid A (SAA) is one of the acute-phase reactants, a group of plasma proteins that increases immensely in concentration during microbial infections and inflammatory conditions, and a close relationship between SAA levels and disease activity in rheumatoid arthritis (RA) has been observed. RA is an inflammatory disease, where neutrophils play important roles, and SAA is thought to participate in the inflammatory reaction by being a neutrophil chemoattractant and inducer of proinflammatory cytokines. The biological effects of SAA are reportedly mediated mainly through formyl peptide receptor like-1 (FPRL1), a G protein-coupled receptor (GPCR) belonging to the formyl peptide receptor family. Here, we confirmed the affinity of SAA for FPRL1 by showing that stably transfected HL-60 cells expressing FPRL1 were activated by SAA and that the response was inhibited by the use of the FPRL1-specific antagonist WRWWWW (WRW4). We also show that SAA activates the neutrophil NADPH-oxidase and that a reserve pool of receptors is present in storage organelles mobilized by priming agents such as TNF-alpha and LPS from Gram-negative bacteria. The induced activity was inhibited by pertussis toxin, indicating the involvement of a GPCR. However, based on FPRL1-specific desensitization and use of FPRL1 antagonist WRW4, we found the SAA-mediated effects in neutrophils to be independent of FPRL1. Based on these findings, we conclude that SAA signaling in neutrophils is mediated through a GPCR, distinct from FPRL1. Future identification and characterization of the SAA receptor could lead to development of novel, therapeutic targets for treatment of RA.
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| 16. |
- Blomgran, Robert, et al.
(författare)
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Cathepsin-cleaved Bid promotes apoptosis in human neutrophils via oxidative stress-induced lysosomal membrane permeabilization
- 2007
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 81, s. 1213-1223
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Tidskriftsartikel (refereegranskat)abstract
- Lysosomal membrane permeabilization (LMP) is emerging as an important regulator of cell apoptosis. Human neutrophils are highly granulated phagocytes, which respond to pathogens by exhibiting increased production of reactive oxygen species (ROS) and lysosomal degranulation. In a previous study, we observed that intracellular, nonphagosomal generation of ROS triggered by adherent bacteria induced ROS-dependent neutrophil apoptosis, whereas intraphagosomal production of ROS during phagocytosis had no effect. In the present study, we measured lysosomal membrane stability and leakage in human neutrophils and found that adherent, noningested, Type 1-fimbriated Escherichia coli bacteria induced LMP rapidly in neutrophils. Pretreatment with the NADPH oxidase inhibitor diphenylene iodonium markedly blocked the early LMP and apoptosis in neutrophils stimulated with Type 1-fimbriated bacteria but had no effect on the late LMP seen in spontaneously apoptotic neutrophils. The induced lysosomal destabilization triggered cleavage of the proapoptotic Bcl-2 protein Bid, followed by a decrease in the antiapoptotic protein Mcl-1. Involvement of LMP in initiation of apoptosis is supported by the following observations: Bid cleavage and the concomitant drop in mitochondrial membrane potential required activation of cysteine-cathepsins but not caspases, and the differential effects of inhibitors of cysteine-cathepsins and cathepsin D on apoptosis coincided with their ability to inhibit Bid cleavage in activated neutrophils. Together, these results indicate that in microbe-induced apoptosis in neutrophils, ROS-dependent LMP represents an early event in initiation of the intrinsic apoptotic pathway, which is followed by Bid cleavage, mitochondrial damage, and caspase activation.
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| 17. |
- Borregaard, N, et al.
(författare)
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Neutrophils and keratinocytes in innate immunity--cooperative actions to provide antimicrobial defense at the right time and place
- 2005
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 77:4, s. 439-443
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Tidskriftsartikel (refereegranskat)abstract
- The human neutrophil is a professional phagocyte of fundamental importance for defense against microorganisms, as witnessed by the life-threatening infections occurring in patients with neutropenia or with defects that result in decreased microbicidal activity of the neutrophil [1, 2]. Likewise, the skin and mucosal surfaces provide important barriers against infections. Traditionally, these major defense systems, the epithelial cells and the neutrophils, have been viewed as limited in their armory: The epithelial cells provide defense by constituting a physical barrier, and the neutrophils provide instant delivery of preformed antimicrobial substances or on-the-spot assembly of the multicomponent reduced nicotinamide adenine dinucleotide phosphate oxidase from stored components for the generation of reactive oxygen metabolites. Recent research has shown that epithelial cells are highly dynamic and able to generate antimicrobial peptides in response not only to microbial infection itself [3–6] but more importantly, to the growth factors that are called into play when the physical barrier is broken, and the risk of microbial infection is imminent [7]. Likewise, the neutrophil changes its profile of actively transcribed genes when it diapedeses into wounded skin [8]. This results in generation of signaling molecules, some of which support the growth and antimicrobial potential of keratinocytes and epithelial cells. This paper will highlight some recent advances in this field.
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| 18. |
- Burkert, E, et al.
(författare)
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Cell type-dependent activation of 5-lipoxygenase by arachidonic acid
- 2003
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 73:1, s. 191-200
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Tidskriftsartikel (refereegranskat)abstract
- 5-Lipoxygenase (5-LO) is the key enzyme in the biosynthesis of proinflammatory leukotrienes. We show that stimulation of polymorphonuclear leukocytes (PMNL), rat basophilic leukemia (RBL)-1, or transfected HeLa cells with arachidonic acid (AA) caused prominent 5-LO product formation that coincided with the activity of extracellular signal-regulated kinases (ERKs) and p38 mitogen-activated protein kinase. 5-LO product formation in AA-stimulated PMNL and RBL-1 cells was independent of Ca2+. However, in HeLa cells expressing a 5-LO mutant lacking potential 5-LO phosphorylation sites, removal of Ca2+ caused a prominent loss of 5-LO activity. For Mono Mac 6 (MM6) cells, A failed to activate ERKs, and AA-induced 5-LO product formation was only minute. Also, activation of ERKs by phorbol esters did not lead to prominent 5-LO product synthesis. Instead, 5-LO activation in MM6 cells required Ca2+ or alternative signaling pathways induced by hyperosmotic stress. In summary, mechanisms for activation of 5-LO differ considerably between cell types.
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| 19. |
- Casado-Bedmar, Maite, et al.
(författare)
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Elevated F-EDN correlates with mucosal eosinophil degranulation in patients with IBS : A possible association with microbiota?
- 2022
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Ingår i: Journal of Leukocyte Biology. - : Alan R. Liss Inc.. - 0741-5400 .- 1938-3673. ; 111:3, s. 655-665
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Tidskriftsartikel (refereegranskat)abstract
- Eosinophils have been linked to functional dyspepsia; however, less is known about their role in irritable bowel syndrome (IBS). This study tested the hypothesis of alterations in levels of fecal eosinophil-derived neurotoxin (F-EDN) and eosinophil density and degranulation within the colonic mucosa of IBS patients compared with healthy controls (HC). Colonic biopsies were collected from 37 IBS patients and 20 HC and analyzed for eosinophil numbers and local degranulation of eosinophil cationic protein (ECP) by histologic procedures. Fecal samples were collected for F-EDN and microbiota analysis. Differentiated 15HL-60 cells were used in vitro to investigate the direct effect of live bacteria on eosinophil activation measured by a colorimetric assay with o-phenylenediamine (OPD) substrate. We observed a higher number of eosinophils and increased extracellular ECP in the mucosa of IBS patients compared with HC. Moreover, F-EDN levels in IBS samples were elevated compared with HC and positively correlated to extracellular ECP. Metagenomic analysis showed significant correlations between bacterial composition and eosinophil measurements in both HC and IBS patients. In vitro experiments revealed an increased degranulation of 15HL-60 after stimulation with Salmonella typhimurium, Salmonella enterica, and Yersinia enterocolitica. To conclude, we could demonstrate alterations related to eosinophils in IBS, and, for the first time, a positive correlation between F-EDN levels and degranulated eosinophils in the colonic mucosa of IBS patients. Together our results suggest that eosinophils play a role in the pathophysiology of IBS and the mechanisms might be linked to an altered microbiota.
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| 20. |
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| 21. |
- Christenson, Karin, et al.
(författare)
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In vivo-transmigrated human neutrophils are resistant to antiapoptotic stimulation.
- 2011
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 90:6, s. 1055-63
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophils respond to microbial invasion or injury by transmigration from blood to tissue. Transmigration involves cellular activation and degranulation, resulting in altered levels of surface receptors and changed responsiveness to certain stimuli. Thus, fundamental functional changes are associated with neutrophil transmigration from blood to tissue. Neutrophils isolated from peripheral blood spontaneously enter apoptosis, a process that can be accelerated or delayed by different pro- or antiapoptotic factors. How tissue neutrophils that have transmigrated in vivo regulate cell death is poorly understood. In this study, in vivo-transmigrated neutrophils (tissue neutrophils) were collected using a skin chamber technique and compared with blood neutrophils from the same donors with respect to regulation of cell death. Skin chamber fluid contained a variety of cytokines known to activate neutrophils and regulate their lifespan. Freshly prepared tissue neutrophils had elevated activity of caspase 3/7 but were fully viable; spontaneous cell death after in vitro culture was also similar between blood and tissue neutrophils. Whereas apoptosis of cultured blood neutrophils was delayed by soluble antiapoptotic factors (e.g., TLR ligands), tissue neutrophils were completely resistant to antiapoptotic stimulation, even though receptors were present and functional. In vitro transmigration of blood neutrophils into skin chamber fluid did not fully confer resistance to antiapoptotic stimulation, indicating that a block of antiapoptotic signaling occurs specifically during in vivo transmigration. We describe a novel, functional alteration that takes place during in vivo transmigration and highlights the fact that life and death of neutrophils may be regulated differently in blood and tissue.
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| 22. |
- Christenson, Karin, et al.
(författare)
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Serum amyloid A inhibits apoptosis of human neutrophils via a P2X7-sensitive pathway independent of formyl peptide receptor-like 1
- 2008
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 83:1, s. 139-48
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophil apoptosis is important for the termination of inflammatory reactions, in that it ensures placid clearance of these potently cytotoxic cells. Various proinflammatory cytokines delay neutrophil apoptosis, which may result in accumulation of these cells, sometimes accompanied by tissue destruction, potentially leading to various inflammatory disease states. Rheumatoid arthritis (RA) is characterized frequently by elevated levels of the acute-phase reactant serum amyloid A (SAA) in circulation and in tissues. SAA is emerging as a cytokine-like molecule with the ability to activate various proinflammatory processes, many of which involve signaling via the formyl peptide receptor-like 1 (FPRL1). In this study, we show that SAA, purified from plasma from RA patients or in recombinant form, suppressed apoptosis of human neutrophils. Blocking FPRL1 did not lessen the antiapoptotic effects of SAA, implying the action of a receptor distinct from FPRL1. In contrast, antagonists of the nucleotide receptor P2X7 abrogated the antiapoptotic effect of SAA completely but did not block intracellular calcium transients evoked by SAA stimulation. Based on these results and also the finding that blocking P2X7 inhibited antiapoptotic actions of unrelated stimuli (LPS and GM-CSF), we propose that P2X7 is a general mediator of antiapoptotic signaling in neutrophils rather than a bona fide SAA receptor.
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| 23. |
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| 24. |
- Ciaglia, E, et al.
(författare)
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N6-isopentenyladenosine, an endogenous isoprenoid end product, directly affects cytotoxic and regulatory functions of human NK cells through FDPS modulation
- 2013
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 94:6, s. 1207-1219
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Tidskriftsartikel (refereegranskat)abstract
- iPA is a naturally occurring nucleoside with an isopentenyl moiety derived from the mevalonate pathway and a well-established anti-tumor activity. In analogy to the unique specificity for phosphoantigens, such as IPP, shown by human Vγ9Vδ2 T cells, here, we report for the first time the ability of iPA to selectively expand and directly target human NK cells. Interestingly, submicromolar doses of iPA stimulate resting human NK cells and synergize with IL-2 to induce a robust activation ex vivo with significant secretion of CCL5 and CCL3 and a large increase in TNF-α and IFN-γ production when compared with IL-2 single cytokine treatment. Moreover, iPA promotes NK cell proliferation and up-regulates the expression of specific NK cell-activating receptors, as well as CD69 and CD107a expression. Accordingly, this phenotype correlates with significantly greater cytotoxicity against tumor targets. At the molecular level, iPA leads to a selective, potent activation of MAPK signaling intermediaries downstream of the IL-2R. The effect results, at least in part, from the fine modulation of the FDPS activity, the same enzyme implicated in the stimulation of the human γδ T cells. The iPA-driven modulation of FDPS can cause an enhancement of post-translational prenylation essential for the biological activity of key proteins in NK signaling and effector functions, such as Ras. These unanticipated properties of iPA provide an additional piece of evidence of the immunoregulatory role of the intermediates of the mevalonate pathway and open novel therapeutic perspectives for this molecule as an immune-modulatory drug.
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| 25. |
- Collins, Vincent, 1962, et al.
(författare)
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Endogenously oxidized mitochondrial DNA induces in vivo and in vitro inflammatory responses
- 2004
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Ingår i: J Leukoc Biol. - : Oxford University Press (OUP). - 0741-5400. ; 75:6, s. 995-1000
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Tidskriftsartikel (refereegranskat)abstract
- We report that mitochondrial DNA (mtDNA) is inflammatogenic in vitro and in vivo as a result of the presence of unmethylated CpG sequences and its oxidative status. Purified human and murine mtDNAs induced arthritis when injected intra-articularly (i.a.) in mice. Importantly, oligodeoxynucleotide that contained a single oxidatively damaged base also induced arthritis when injected i.a. in mice. In contrast, neither human nor murine nuclear DNA induced inflammation. mtDNA-induced arthritis was neither B cell- nor T cell-dependent but was mediated by monocytes/macrophages. mtDNA-induced nuclear factor-kappaB stimulation resulted in the production of tumor necrosis factor alpha, a potent, arthritogenic factor. Finally, extracellular mtDNA was detected in the synovial fluids of rheumatoid arthritis patients but not of control subjects. We conclude that endogenous mtDNA displays inflammatogenic properties as a result of its content of unmethylated CpG motifs and oxidatively damaged adducts.
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