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At least 307 records · Page 17Linked to original sources
PubMed2003

Crystal-induced neutrophil activation: VIII. Immediate production of prostaglandin E2 mediated by constitutive cyclooxygenase 2 in human neutrophils stimulated by urate crystals.

OBJECTIVE: To evaluate the impact of monosodium urate monohydrate (MSUM) crystals on the synthesis of prostaglandin E(2) (PGE(2)) by human neutrophils, and to examine some of the mechanisms underlying these responses. METHODS: The amount of PGE(2) released in the supernatants of stimulated human neutrophils was evaluated by enzyme immunoassay, and expression of cyclooxygenase 2 (COX-2) was monitored by immunoblot on cell lysates, as well as by cytofluorometry of buffy-coat cells. RESULTS: We observed that MSUM crystals rapidly stimulated the synthesis of PGE(2), with levels peaking at 1 hour. This response was decreased by NS-398, a specific inhibitor of COX-2. We also detected a constitutive expression of COX-2 in unstimulated and unprimed neutrophils. This rapid COX-2-dependent PGE(2) accumulation was independent of translation and transcription. We also observed that piceatannol, but not colchicine, blocked the synthesis of PGE(2) stimulated by MSUM crystals. CONCLUSION: These results show that the interaction of MSUM crystals with human neutrophils stimulates a significant synthesis of PGE(2) mediated by constitutively expressed COX-2. The results of this study emphasize the potential importance of the neutrophil as a source of PGE(2), which may modulate, positively or negatively, the inflammatory response.

Arachidonic Acid↗
PubMed2001

Neutrophil functions of patients with vasculitis related to myeloperoxidase-specific anti-neutrophil antibody.

Neutrophils are hypothesized to cause tissue damage resulting in the development of vasculitis and glomerulonephritis, although they are known to primarily take part in host defense functions. The infiltration of inflammatory cells. notably neutrophils and macrophages, is observed in the progression of vasculitis. Neutrophils with activated status and anti-neutrophil cytoplasmic antibodies (ANCAs), especially myeloperoxidase-specific (MPO)-ANCA, have been implicated in the development of vasculitis. The target molecule of MPG-ANCA is a lysosomal enzyme MPO that usually acts to kill bacteria, viruses, and fungi and that causes damage to the tissue due to the toxicity of its product, hypochlorite (OCl-). To elucidate the role of MPO-ANCA in the progression of vasculitis, a set of MPO-peptide fragments has been developed, and the corresponding epitope site for the specific monoclonal and/or oligoclonal antibody resulting in vasculitis has been determined. Recently some mouse models have been used for analyzing the correlation between MPO and MPO-ANCA in relation to damage of blood vessels followed by the development of vasculitis. This review focuses on the role of activated neutrophils in the development of vasculitis associated with MPO-ANCA and the target molecules of ANCA. In addition, the reactivities of ANCA and inflammatory cytokines involving leukocyte-derived chemotaxin 2 (LECT2) are also discussed.

Animals↗
PubMed2002

Potential role of IL-8, platelet-activating factor and TNF-alpha in the sequestration of neutrophils in the lung: effects on neutrophil deformability, adhesion receptor expression, and chemotaxis.

The microvasculature of the normal lung contains a pool of sequestered neutrophils, which is markedly enhanced in acute lung inflammation. Lung neutrophil sequestration is determined by the cells' deformability and adhesivity to capillary endothelium, and is a pre-requisite for emigration into the airspaces. We assessed the effect of several pro-inflammatory mediators associated with acute lung inflammation on these factors. Platelet-activating factor, IL-8 and formyl-Met-Leu-Phe (fMLP) induced a marked, but transient reduction in neutrophil deformability. Also, increased surface expression of the beta(2)-integrin and CD11b, and shedding of L-selectin (CD62L) was observed for these stimuli. TNF-alpha in contrast caused a small decrease in cell deformability only after 30 min, and shedding of L-selectin, but no change in CD11b levels. However, TNF-alpha-pretreatment markedly enhanced the fMLP response for cell deformability, CD11b expression and CD62L loss. Moreover, all pre-treatments were found to induce chemokinesis, and all except fMLP, enhanced fMLP-directed chemotaxis. We were able to demonstrate, using specific TNF-alpha receptor antagonists, that the TNF-alpha-induced changes in chemotaxis were mediated through the 55-kDa receptor. Also, inhibitors of the mitogen activated protein (MAP) kinase signaling pathway showed that the p38 MAP kinase pathway was involved for fMLP-directed chemotaxis of TNF-pretreated neutrophils, although activation of the extracellular signal-regulated kinase (ERK) pathway was also seen. These data demonstrate the differential role of pro-inflammatory mediators in controlling neutrophil sequestration and migration, which may orchestrate the severity of the inflammatory response in such respiratory diseases as chronic obstructive pulmonary disease and asthma.

Cell Adhesion↗
PubMed2000

Regulatory effects of interleukin-4 and interleukin-10 on human neutrophil function ex vivo and on neutrophil influx in a rat model of arthritis.

OBJECTIVE: To assess the capacity of interleukin-4 (IL-4) and IL-10 to block polymorphonuclear neutrophil (PMN) activation in an ex vivo human model system, and to confirm their effect on neutrophil function in an animal model of arthritis. METHODS: The ex vivo phagocytic capacity of cytokine-activated human PMNs was assessed by use of assays for measuring the ingestion of heat-killed yeast and by subsequent hexose-monophosphate shunt activation using nitroblue tetrazolium reduction. The in vivo activity of IL-4 and IL-10 was measured using a rat adjuvant arthritis model in which the mycobacterial antigen concentration was titrated to modify disease intensity. RESULTS: IL-4 and IL-10 suppressed the ex vivo activation state of interferon-gamma- and tumor necrosis factor alpha-activated human neutrophils. In the rat adjuvant arthritis model, treatment with systemic murine IL-10 (mIL-10) effectively suppressed all disease parameters in rats that received the lower concentrations of mycobacteria, whereas systemic mIL-4 was effective against even the most severe disease. Both cytokines were effective in lowering the absolute PMN cell number recovered and the PMN activation state in the joint synovia. We also observed lower levels of the messenger RNA transcript for CINC protein (cytokine-induced neutrophil chemoattractant; a rat homolog for human IL-8) in the synovia. CONCLUSION: IL-10 is an effective antiarthritic agent and has a major effect on the presence and function of PMNs in the joint synovia when disease intensity is not severe. IL-4 has an inhibitory profile that is similar to that of IL-10, but is effective in modifying even the most severe disease. Both cytokines reduced the phagocytic activation of human PMNs in response to proinflammatory cytokines. These data demonstrate that IL-4 and IL-10 can exert powerful regulatory effects on neutrophil function that translate into a therapeutic response in a disease model of arthritis. Treatment with these cytokines alone or in combination may therefore be very useful in the management of patients with rheumatoid arthritis.

Animals↗
PubMed1994

Differential expression of two major cytokines produced by neutrophils, interleukin-8 and the interleukin-1 receptor antagonist, in neutrophils isolated from the synovial fluid and peripheral blood of patients with rheumatoid arthritis.

OBJECTIVE: Neutrophils have been shown to produce interleukin-8 (IL-8) and interleukin-1 receptor antagonist (IL-1ra) in large amounts compared with other cytokines. Since IL-8 has a proinflammatory action whereas IL-1ra is antiinflammatory, our objective was to examine the relative levels of production of these cytokines by synovial fluid (SF) neutrophils isolated from patients with rheumatoid arthritis (RA). METHODS: We measured cytokine production using an enzyme-linked immunosorbent assay and analyzed messenger RNA accumulation in cells by Northern blot. RESULTS: SF neutrophils produced significantly more IL-8 and IL-1 beta, but significantly less IL-1ra, than peripheral blood neutrophils. CONCLUSION: These observations provide new information on the production of pro- and antiinflammatory molecules by neutrophils in the SF environment, and their possible role in RA.

Arthritis, Rheumatoid↗
PubMed1999

The individual regulation of granule protein mRNA levels during neutrophil maturation explains the heterogeneity of neutrophil granules.

The in vivo mRNA levels for 16 granule proteins during neutrophil differentiation were determined to address the question of whether the synthesis of granule proteins is regulated individually or blockwise. RNA was extracted from peripheral blood granulocytes and three different populations of neutrophil precursors isolated from human bone marrow by Percoll density centrifugation. The mRNA levels in relation to the maturation of the cells were determined by Northern blot for the 12 matrix proteins myeloperoxidase, proteinase-3, elastase, defensin, lactoferrin, NGAL, hCAP-18, transcobalamin-I, SGP28, gelatinase, lysozyme, and serglycin and the 4 membrane proteins CD68, CD11b, N-formyl-methionyl-leucyl-phenylalanine receptor, and CD35. This panel of transcripts ensured that markers for all exocytosable organelles of the neutrophil were included in the study. A highly differentiated distribution of mRNAs for granule proteins was demonstrated that can explain the heterogeneity of the intracellular storage granules and secretory vesicles of the neutrophil. Furthermore, the individual distribution of these transcripts provides the basis for a more detailed assessment of neutrophil maturation than that obtained by morphological studies or the use of a single marker protein for azurophil, specific, and gelatinase granules.

Blood Proteins↗
PubMed1995

Isolation and sequence determination of 6- and 8-kDa precursors of human neutrophil peptides from bone marrow, plasma and peripheral blood neutrophils.

Human neutrophil peptides (HNPs) are 29 to 30 amino acid antimicrobial peptides localized in the azulophil granules in neutrophils. We isolated endogenous molecular forms of HNPs from normal human bone marrow, plasma and peripheral blood neutrophils and determined their primary structures to investigate their post-translational processing. HNPs initially are synthesized as 94 amino acid precursors that produce 75 amino acid pro-HNPs by cleavage of a signal peptide. The majority of pro-HNPs was processed to 56 amino acid intermediates by preaspartate proteolytic cleavage in the bone marrow then to mature HNPs in peripheral blood neutrophils. Part of pro-HNPs was released into the plasma, in which they constituted 25-30% of the HNP molecules. Pro-HNPs and their mRNAs were detected both in peripheral blood neutrophils and bone marrow. Identification of the post-translational processing products of HNPs should provide a better understanding of the biosynthesis of the peptides.

Adult↗
PubMed2001

Neutrophils, endothelial cells, and cysteinyl leukotrienes: a new approach to neutrophil-dependent inflammation?

Cysteinyl leukotrienes (cys-LT) have been historically involved with the pathogenesis of asthma, and cys-LT receptor antagonists and synthesis inhibitors are currently in use for the therapy of this disease. Nevertheless cys-LT possess very potent proinflammatory activities and may play a significant role in inflammatory processes other than asthma. Recent evidences obtained in our laboratory, as well as in others, show that unexpected, biologically significant amounts of cys-LT are formed upon cell-cell cooperation between neutrophils and endothelial cells, resulting from transfer of the synthesis intermediate leukotriene A4 from neutrophils to endothelial cells. Cys-LT formed upon neutrophil adhesion to endothelial cells may contribute to the alterations of microvasculature associated with the inflammatory response. In particular, nonsteroidal anti-inflammatory drug (NSAIDs)-induced neutrophil adhesion to gastric wall microvessels may contribute to the gastric damage associated to the use of NSAIDs. In agreement with this hypothesis, dual 5-LOX/COX inhibitors are characterized by reduced gastric damage when compared to nonspecific COX-inhibitors. Evidence provide support for the involvement of cys-LT in neutrophil-dependent inflammatory responses and suggest new potential application of 5-LO inhibition in anti-inflammatory pharmacological treatment.

Animals↗
PubMed1996

N-acetylcysteine pretreatment of cardiac surgery patients influences plasma neutrophil elastase and neutrophil influx in bronchoalveolar lavage fluid.

OBJECTIVE: Study of leukocyte activation and release of toxic mediators during extracorporeal circulation (ECC). ECC can be used to study the potential protective effect of a pharmacon against neutrophil-mediated lung injury. Clinical studies have indicated that N-acetylcysteine (NAC) may improve systemic oxygenation and reduce the need for ventilatory support when given to patients with acute lung injury. DESIGN: Cardiac surgery patients were pretreated with high-dose NAC in order to assess the potential role of NAC to interfere with neutrophil-mediated inflammation and lung injury. PATIENTS: 18 patients who underwent ECC: group 1 (n = 8) no premedication (only placebo); group 2 (n = 10) NAC (72 mg/kg i.v. as a bolus, later 72 mg/kg over 12 h). MEASUREMENTS AND RESULTS: In group 2, the partial pressure of oxygen in arterial blood/fractional inspired oxygen 4 h after surgery was significantly higher than in group 1 (213 +/- 31 vs 123 +/- 22; p = 0.044). NAC pretreatment prevented an increase in plasma neutrophil elastase activity (18.9 +/- 6.9 vs 49.9 +/- 5.6 ng/ml in group 1 at the end of ECC; p = 0.027). Release of myeloperoxidase (MPO) was not affected (group 1:1105 +/- 225 ng/ml vs group 2:1127 +/- 81 at the end of ECC; p = 0.63). At the end of ECC, total antigenic human neutrophil elastase (group 1:671 +/- 72 ng/ml vs group 2:579 +/- 134; p = 0.37) and complex formation between elastase and alpha 1-proteinase inhibitor were no different in the two groups. There were no significant difference in cellular composition and mediators in the lavage fluid, although values for total number of neutrophils, elastase, MPO and interleukin-8 were lower in group 2. CONCLUSION: Pretreatment with NAC may prevent lung injury by diminishing elastase activity. Since the release of mediators, especially MPO, is not affected, this diminished activity of elastase may be achieved by enhanced inactivation by antiproteases after initial treatment.

Acetylcysteine↗
PubMed1987

The bioflavonoid quercetin inhibits neutrophil degranulation, superoxide production, and the phosphorylation of specific neutrophil proteins.

Quercetin, a C-kinase antagonist, inhibits neutrophil degranulation and superoxide production induced by f-met-leu-phe, solid phase IgG, zymosan treated serum and a phorbol ester (PMA). Quercetin is more effective in inhibiting degranulation (IC50 = 20 uM) than superoxide production (IC50 = 80 microM). Neutrophil activation by PMA is accompanied by the phosphorylation of neutrophil proteins of 205, 170, 130, 91, 77, 67, 56, 47, 39, 34, 27, and 20 kilodaltons; quercetin also inhibits the phosphorylation of these proteins. Dose-response studies indicated that phosphorylation of the 67 kilodalton protein was particularly sensitive to inhibition by quercetin at concentrations that also inhibit neutrophil degranulation and superoxide production. These results suggest that phosphorylation of the 67 kilodalton protein may be an important intracellular reaction associated with neutrophil activation.

Adult↗
PubMed1989

Human neutrophils contain distinct cytosolic and particulate tyrosine kinase activities: possible role in neutrophil activation.

Tyrosine protein kinase activities were partially purified from circulating human neutrophils. Purification steps involved sequential chromatography on DEAE-Sephacel, gel filtration and affinity chromatography on a column composed of a glutamine:tyrosine copolymer linked to AH-Sepharose. The results indicate that human neutrophils contain a tyrosine kinase activity in the 150,000 x g cytosolic fraction which is distinct from the activity in a detergent extractable 150,000 x g particulate fraction. These enzyme activities are dependent on the divalent cations Mn2+ and Mg2+. Kinetics for the phosphorylation of a glutamine:tyrosine copolymer substrate demonstrated an apparent Km for the cytosolic tyrosine kinase activity of 22.3 +/- 0.3 microM, and an apparent Km for the particulate extract activity of 42.7 +/- 6.0 microM. By gel filtration chromatography, the cytosolic and particulate tyrosine kinase activities have approximate molecular masses of 80-90 and 50-60 kDa, respectively. The particulate but not the cytosolic neutrophil tyrosine kinase activity was inhibited by a novel tyrosine kinase inhibitor ST638. ST638 inhibited superoxide production in intact neutrophils stimulated with the chemotactic peptide F-Met-Leu-Phe, opsonized zymosan particles, and sodium fluoride. ST638 did not, however, inhibit superoxide production in neutrophils stimulated with phorbol myristate acetate or the calcium ionophore, A23187.

Cations, Divalent↗
PubMed1990

Neutrophilic dermatosis with myelodysplastic syndrome: nuclear segmentation anomalies of neutrophils in the skin lesion and in peripheral blood.

Neutrophilic dermatosis developed in two patients with myelodysplastic syndrome. Biopsy specimens of their skin lesions showed marked infiltration by neutrophils with nuclear anomalies, that is, hyposegmentation (pseudo-Pelger-Huët anomaly) or hypersegmentation. Peripheral blood and bone marrow neutrophils had similar anomalies. To our knowledge, this is the first report of nuclear segmentation anomalies of neutrophils in neutrophilic dermatosis skin lesions of patients with myelodysplastic syndrome.

Female↗
PubMed2003

Human neutrophil lipocalin: a specific marker for neutrophil activation in severe Plasmodium falciparum malaria.

We have earlier indicated neutrophil activation in severe malaria by measuring myeloperoxidase (MPO) and lysozyme, leukocyte granule proteins secreted by neutrophils as well as by other blood cells (monocytes/macrophages). In this study we evaluated the plasma levels of human neutrophil lipocalin (HNL), a specific neutrophil granule protein, in relation to previously reported markers MPO and lysozyme, for clinical significance in indicating severe malaria. For this purpose, plasma samples were analyzed from 65 individuals with severe malaria, mild malaria or malaria negative, all living in the Gedarif area of Sudan. The plasma levels of HNL were significantly higher in the group of patients with severe malaria as compared with the other two groups. Plasma levels of HNL correlated significantly to those of MPO and lysozyme, as well as to body temperature, degree of parasitaemia and pulse rate. These results confirm our previous findings that neutrophils are activated in-patients with severe malaria and the level of HNL is a good marker in this context.

Acute-Phase Proteins↗
PubMed1995

Role of neutrophils in radical production during ischemia and reperfusion of the rat brain: effect of neutrophil depletion on extracellular ascorbyl radical formation.

A growing body of experimental data indicate that oxygen radicals may mediate the brain injury during ischemia-reperfusion. One potential source of oxygen radicals is activated neutrophils. To study the role of neutrophils in radical production during cerebral ischemia-reperfusion, we evaluated the effects of depletion of circulating neutrophils by administration of an anti-neutrophil monoclonal antibody (RP3) on radical formation in rats with 1-h middle cerebral artery (MCA) occlusion. In the present study, we employed a new electron spin resonance method coupled with brain microdialysis. The method uses the endogenous ascorbyl radical (AR) concentration as a marker of oxygen radicals and requires no spin-trapping agents. In the vehicle controls, extracellular AR decreased during MCA occlusion. After reperfusion, AR significantly increased at 30 min and 1 h, returned to near basal level until 2 h, and increased again at 24 h after reperfusion. In the rats treated with RP3, AR decreased during MCA occlusion to the same extent as in the vehicle control. However, RP3 treatment completely inhibited the increase in extracellular AR after reperfusion. RP3 treatment exerted no effect on the changes in extracellular ascorbate or tissue PO2 throughout the experimental period. In conclusion, neutrophils are a major source of oxygen radicals during reperfusion after focal cerebral ischemia.

Animals↗
PubMed1995

Abnormal neutrophil phenotype and neutrophil FcRIII deficiency corrected by bone marrow transplantation.

BACKGROUND: Neutrophils from a patient in first remission of acute myeloid leukemia were found to lack NA1 and NA2 alloantigens. This NA null phenotype was converted to the normal phenotype of NA1, NB2 by the transplantation of bone marrow from an HLA-identical sibling. To investigate the inherited or acquired nature of this rare phenotype, a combination of conventional neutrophil serology and recently developed restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR) assays was used. STUDY DESIGN AND METHODS: Diagnosis, remission, and posttransplant patient peripheral blood samples were used for neutrophil phenotyping by granulocyte agglutination and immunofluorescence tests. The presence and dose of the gene for neutrophil Fc gamma RIIIb (Fc gamma RIIIB) were tested for with RFLP and Southern analysis and PCR-based RFLP tests. Plasma levels of circulating soluble Fc gamma RIII (sFc gamma RIII) were measured with radioimmunoassay. The sibling bone marrow donor and the patient's parents were also studied. RESULTS: RFLP analysis of DNA obtained from the patient at the time of diagnosis showed that she lacked the Fc gamma RIIIB gene for neutrophil Fc gamma RIII (i.e., Fc gamma RIIIb), but that, in DNA prepared from posttransplant samples, the Fc gamma RIIIB gene was present. Quantitation of plasma levels of soluble FcRIII (sFcRIII) demonstrated a complete absence of sFcRIII in the patient's pretransplant plasma. However, 20 units of sFcRIII were detected in the patient's plasma by 160 days after graft. Hair samples from the patient provided sufficient nonhematopoietic, genomic DNA to confirm that her genotype was NA0NA0. DNA prepared from lymphocytes of both parents and the sibling marrow donor was used to quantitate their Fc gamma RIIIB gene dose. The mother and brother had only one Fc gamma RIIIB gene each, while the father apparently had a normal complement of two Fc gamma RIIIB genes. CONCLUSION: In this case, an inherited absence of Fc gamma RIIIB gene in a patient with acute myeloid leukemia was unintentionally corrected by the transplantation of bone marrow from a sibling donor who himself carried only one Fc gamma RIIIB gene.

Adult↗
PubMed2003

Purification of ovine neutrophils and eosinophils: Anaplasma phagocytophilum affects neutrophil density.

Studies on the functions of ovine granulocytes require pure and functionally active populations of neutrophils and eosinophils. This report describes an improved technique for the separation of neutrophils and eosinophils from the peripheral blood of sheep infected with Anaplasma phagocytophilum and from normal sheep. After centrifugation and discarding the buffy coat layer, which contains the bulk of mononuclear cells, neutrophils with a high degree of purity (94.87 [+/-1.7]%, n=9) and good yield (69 [+/-9]%, n=9) were obtained by density gradient centrifugation on Percoll with a density of 1.09 g/ml (65%). However, this density was not suitable for neutrophils obtained from sheep during the peak period of A. phagocytophilum bacteraemia. Improved purity of infected neutrophils was obtained when the leucocytes were separated on Percoll with a density of 1.08 g/ml (55%). Relatively good purity of eosinophils was obtained when leucocytes from normal sheep were separated on Percoll with a density of 1.10 g/ml (70%). Ovine eosinophils formed a distinct band just below the band of mononuclear cells when a continuous Percoll gradient with a density of 1.10 g/ml was used. The purity of the eosinophils obtained was 87.7 (+/-12.5)% (n=6; range 64.1-97.6%), with a mean recovery rate of 61.9 (+/-20.3)%.

Anaplasma phagocytophilum↗
PubMed1985

Effect of dietary enrichment with eicosapentaenoic and docosahexaenoic acids on in vitro neutrophil and monocyte leukotriene generation and neutrophil function.

The effects of dietary fish-oil fatty acids on the function of the 5-lipoxygenase pathway of peripheral-blood polymorphonuclear leukocytes and monocytes were determined in seven normal subjects who supplemented their usual diet for six weeks with daily doses of triglycerides containing 3.2 g of eicosapentaenoic acid and 2.2 g of docosahexaenoic acid. The diet increased the eicosapentaenoic acid content in neutrophils and monocytes more than sevenfold, without changing the quantities of arachidonic acid and docosahexaenoic acid. When the neutrophils were activated, the release of [3H]arachidonic acid and its labeled metabolites was reduced by a mean of 37 per cent, and the maximum generation of three products of the 5-lipoxygenase pathway was reduced by more than 48 per cent. The ionophore-induced release of [3H]arachidonic acid and its labeled metabolites from monocytes in monolayers was reduced by a mean of 39 per cent, and the generation of leukotriene B4 by 58 per cent. The adherence of neutrophils to bovine endothelial-cell monolayers pretreated with leukotriene B4 was inhibited completely, and their average chemotactic response to leukotriene B4 was inhibited by 70 per cent, as compared with values determined before the diet was begun and six weeks after its discontinuation. We conclude that diets enriched with fish-oil-derived fatty acids may have antiinflammatory effects by inhibiting the 5-lipoxygenase pathway in neutrophils and monocytes and inhibiting the leukotriene B4-mediated functions of neutrophils.

Adult↗