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PubMed1990

Human neutrophils release the Leu-8 lymph node homing receptor during cell activation.

The Leu-8 molecule, the human homologue of the murine MEL-14 peripheral lymph node homing receptor, is expressed on neutrophils in both species and may be important in localization of cells to sites of inflammation. Most circulating human neutrophils express the Leu-8 molecule, and activation of neutrophils with phorbol myristate acetate causes a rapid decline in Leu-8 membrane fluorescence staining within 15 minutes. Northern blot analysis of total cellular RNA from neutrophils demonstrated two species of Leu-8 messenger RNA, a major one of 2.4 kb and a minor one of 1.9 kb. Because two different Leu-8 cDNA clones were obtained from human lymphocytes that were predicted to encode both transmembrane and phosphatidylinositol (PI)-anchored forms of the molecule, experiments were conducted to determine whether Leu-8 is anchored to neutrophils by a PI-anchor. There was a slight decrease in expression of Leu-8 on neutrophils when they were treated with PI-specific phospholipase C (PI-PLC). However, Leu-8 was abundant on neutrophils obtained from a patient with paroxysmal nocturnal hemoglobinuria. To determine the fate of the Leu-8 molecule during cell activation, neutrophils were labeled with 125I-anti-Leu-8. During activation antibody was rapidly lost from the cell surface and was not internalized, suggesting that Leu-8 is released from the cell membrane during cell activation. When cell extracts of neutrophils were compared with extracts of lymphoid cells by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting, the Leu-8 species expressed on neutrophils had a significantly higher and more variable relative mobility (70 to 120 Kd for neutrophils v 70 Kd for Jurkat T cells). In addition, Leu-8 molecules were detected in the supernatants of activated neutrophils. These results indicate that human neutrophils express a high-molecular-weight form of the Leu-8 molecule that has a conventional transmembrane anchor and is rapidly released from the membrane during activation. The loss of the Leu-8 membrane glycoprotein during activation may be a mechanism for rapid alteration of neutrophil adhesion characteristics.

Blotting, Western↗
PubMed1991

Involvement of the CD11b/CD18 integrin, but not of the endothelial cell adhesion molecules ELAM-1 and ICAM-1 in tumor necrosis factor-alpha-induced neutrophil toxicity.

TNF-alpha can incite neutrophil-mediated endothelial cell damage and neutrophil H2O2 release. Both effects require adherent neutrophils. Using specific mAb, we showed in this in vitro study that the CD18 beta 2-chain and the CD11b alpha M-chain of the CD11/CD18 integrin heterodimer have a major role in both TNF-alpha-induced neutrophil-mediated detachment of human umbilical vein endothelial cells and H2O2 release by TNF-alpha-activated human neutrophils. In contrast to anti-CD18 mAb, which consistently prevented neutrophil activation, anti-CD11a mAb and two of three anti-CD11b mAb did not reduce endothelial cell detachment and neutrophil H2O2 release, although they decreased neutrophil adhesion to human umbilical vein endothelial cells. mAb 904, directed against the bacterial LPS binding region of CD11b, reduced endothelial cell detachment for about 40% and neutrophil H2O2 release for more than 50%, demonstrating that CD11b/CD18 is engaged in TNF-induced neutrophil activation. Dependence on CD11b/CD18 could not be overcome by CD18-independent anchoring of neutrophils via PHA. Additionally, neither induction of increased expression of the endothelial cell adhesion molecules ICAM-1 and ELAM-1, nor subsequent addition of specific mAb, influenced endothelial cell injury or H2O2 release by TNF-activated neutrophils. Interaction with ICAM-1 and ELAM-1 therefore appears not to induce additional activation of TNF-stimulated neutrophils. These studies suggest that a specific, CD11b/CD18-mediated signal, instead of adherence only, triggers toxicity of TNF-activated neutrophils.

Antigens, CD↗
PubMed1990

Comparative studies of microscopically determined aggregation, degranulation, and light transmission after chemotactic activation of adult and newborn neutrophils.

Changes in the light transmission of suspensions of activated neutrophils are widely used to measure the dynamics of neutrophil aggregation. Such studies have suggested, for example, that aggregation is irreversible for human newborn neutrophils but fully reversible for adult cells. We have evaluated aggregation directly by microscopic particle counting and compared it with changes in light transmission (delta T) and with release from three granule subsets for neutrophils activated with N-formyl-methionyl-leucyl-phenylalanine (FMLP). Maximal increases in %T in response to 0.5 micromol/L FMLP were approximately 25% larger for newborn than for adult neutrophils, and were only partially reversible by 8 minutes, while %T increases for adult neutrophils were fully reversible. However, measurements of neutrophil aggregation using light microscopy showed that both newborn and adult neutrophils fully deaggregated. A further independence of delta T from aggregation was found by pretreating adult neutrophils with cytochalasin B (5 micrograms/mL) in the presence of 0.5% gelatin, a pretreatment that blocked FMLP-induced neutrophil aggregation while allowing large increases in %T and degranulation. In response to FMLP, newborn neutrophils released more enzyme from each granule subset than did adult neutrophils. Our results suggest that cellular events associated with neutrophil activation (other than aggregation) are implicated in light transmission responses and that these differ for adults and newborns. These results also suggest that reports of neutrophil aggregation should be based on direct particle counting methods rather than on %T responses.

Adult↗
PubMed1989

Regulation of human neutrophil functions by adenine nucleotides.

Previous work has shown that platelet-derived adenine nucleotides modulate neutrophil superoxide anion (O2-) generation. Additional studies were undertaken to characterize the effects of authentic adenosine (ADO) and its nucleotide derivatives on the inflammatory functions of human neutrophils. Stimulus-specific inhibition of neutrophil O2- generation by ADO in response to FMLP was verified. In addition, the ability of ATP, ADP, and AMP to limit neutrophil O2- generation induced by FMLP (0.2 to 0.5 microM) was demonstrated. The concentration producing 50% inhibition for nucleotide inhibition of neutrophil O2- generation was in the rank order of ADO (0.1 microM) less than AMP (0.5 microM) less than ADP less than or equal to ATP (5 microM). Guanine and inosine nucleotides (0.01 to 100 microM) did not inhibit FMLP-stimulated neutrophil O2- generation. Neutrophil degranulation in response to FMLP was only modestly inhibited by adenine nucleotides and ADO. Adenosine and ADP failed to affect chemotaxis of neutrophils stimulated with FMLP. The inability of non-metabolizable analogs to mimic the inhibitory effects of authentic ATP or ADP on the neutrophil O2- response suggested that metabolism of added nucleotides is necessary for their effectiveness. Both TLC and HPLC confirmed that ATP and ADP were converted to AMP and ADO after their incubation with unstimulated or FMLP-activated neutrophils. The addition of adenosine deaminase to neutrophil reaction mixtures in which conversion of added nucleotides was apparent removed detectable ADO but failed to completely abrogate the inhibition of neutrophil O2- generation by accumulated AMP. The kinetics of inhibition of FMLP-induced neutrophil O2- generation by ATP and ADP also indicated that conversion of these nucleotides to ADO and/or AMP may be essential for their ability to reduce neutrophil responses.

Adenine Nucleotides↗
PubMed1989

Function and regulation of the neutrophil MEL-14 antigen in vivo: comparison with LFA-1 and MAC-1.

The CD11/18 (LFA-1, Mac-1) molecules participate in neutrophil adhesion to cultured endothelium in vitro and are critical for effective neutrophil localization into inflamed tissues in vivo. More recently, the MEL-14 Ag, which was first defined as a lymphocyte homing receptor, has also been implicated in inflammatory neutrophil extravasation. Here we compare the regulation and function of these adhesion molecules on neutrophils during the in vivo inflammatory response. The MEL-14 Ag is expressed at high levels on bone marrow and peripheral blood neutrophils, but is lost on neutrophils isolated from the thioglycollate-inflamed peritoneal cavity. In contrast, Mac-1 is up-regulated on inflammatory neutrophils and little change is seen in the level of LFA-1 expression. In vitro activation of bone marrow neutrophils with PMA or leukotriene B4 results in a dose dependent increase in Mac-1 and decrease in MEL-14 Ag expression within 1 h after treatment, thus reflecting what is found during inflammation in vivo. Neutrophils activated in vitro or in vivo (MEL-14Low, Mac-1Hi) do not home to inflammatory sites in vivo, correlating with the loss of the MEL-14 Ag and the increased Mac-1 expression. Anti-LFA-1, anti-Mac-1, or MEL-14 antibody given i.v. suppress neutrophil accumulation within the inflamed peritoneum (38%, 30%, and 37% of medium control, respectively) without affecting the levels of circulating neutrophils. However, when FITC-labeled cells are precoated with the mAb and injected i.v., only MEL-14 inhibits extravasation into the inflamed peritoneum (25% of medium control). Finally, in ex vivo adhesion assays of neutrophil binding to high endothelial venules in inflamed-lymph node frozen sections MEL-14 inhibits greater than 90%. anti-LFA-1 20 to 30% and anti-Mac-1 less than 10% of the binding of bone marrow neutrophils to inflamed-lymph node high endothelial venules. These results confirm that both the MEL-14 antigen and Mac-1/LFA-1 are important in neutrophil localization to inflamed sites in vivo, but suggest that their roles in endothelial cell interactions are distinct.

Animals↗
PubMed1989

Phagocytic and nitroblue tetrazolium reductive properties of mature and immature neutrophils and eosinophils from blood and bone marrow from cows.

Functional capabilities of morphologically mature (segmented) and immature granulocytes (neutrophils and eosinophils) from bone marrow from cows were studied and compared with similar activities of segmented granulocytes from blood. Phagocytosis of Escherichia coli and postphagocytic oxidative metabolic stimulation, measured by nitroblue tetrazolium (NBT) reduction, were evaluated simultaneously. Phagocytosis was observed readily in segmented neutrophils, neutrophilic bands, and metamyelocytes and rarely in myelocytes. Phagocytosis was not seen in promyelocytes and myeloblasts. Neutrophilic bands and metamyelocytes were phagocytically less active than were segmented neutrophils. Washed segmented bone marrow neutrophils possessed phagocytic activity similar to that of blood neutrophils, whereas the activity of unwashed segmented bone marrow neutrophils was markedly less than that of blood neutrophils. Reduction of NBT was observed only in blood segmented neutrophils and bone marrow segmented neutrophils; the magnitude of NBT reduction was significantly (P = less than 0.005) less in bone marrow neutrophils than in blood neutrophils. Eosinophils were phagocytically less competent than were neutrophils. The NBT reduction was observed only in eosinophils from blood, but not in eosinophils from bone marrow.

Animals↗
PubMed1986

Selective inhibition of human neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine by sulfones.

The therapeutic efficacy of the sulfones, dapsone, and sulfoxone in neutrophilic dermatoses may be related to the effects of these drugs on neutrophil function. Therefore we determined whether neutrophil chemotactic migration to various chemoattractants could be inhibited by sulfones in vitro. The chemotactic responses of human neutrophils from healthy donors were tested by using N-formyl-methionyl-leucyl-phenylalanine (F-met-leu-phe), purified human C5a, and leukocyte-derived chemotactic factor (LDCF). Therapeutic concentrations of sulfones selectively inhibited neutrophil chemotaxis to F-met-leu-phe, but did not affect neutrophil chemotaxis to LDCF or C5a. Inhibition of neutrophil chemotaxis to F-met-leu-phe was induced by both dapsone and sulfoxone at a concentration of 10 micrograms/ml without affecting random migration, and the inhibition was reversed by washing the neutrophils. When dapsone- and sulfoxone-treated neutrophils (100 micrograms/ml) were stimulated with F-met-leu-phe, neutrophil superoxide generation was not inhibited. Sulfapyridine (10 micrograms/ml) also selectively inhibited neutrophil chemotaxis to F-met-leu-phe; however, sulfamethoxazole and sulfisoxazole did not affect chemotaxis. The inhibitory effects of dapsone, sulfoxone, and sulfapyridine could not be demonstrated with granulocytes from rabbits or guinea pigs nor with human monocytes. Experiments with radiolabeled dapsone showed rapid, nonspecific, and reversible binding of dapsone to human neutrophils. These data suggest that a mechanism of action of sulfones in neutrophilic dermatoses may be a selective inhibition of neutrophil migration to as yet undefined chemoattractants in the skin.

Animals↗
PubMed1986

An endothelial cell surface factor(s) induced in vitro by lipopolysaccharide, interleukin 1, and tumor necrosis factor-alpha increases neutrophil adherence by a CDw18-dependent mechanism.

We examined the role of the neutrophil membrane antigen complex designated CDw18 (LFA-1/Mac-1/p150, 95) in human peripheral blood neutrophil adherence to cultured human umbilical vein endothelial cells (HEC) pretreated with lipopolysaccharide (LPS), interleukin 1 (IL 1), or recombinant tumor necrosis factor-alpha (rTNF-alpha). Pretreatment of HEC with LPS produced a dose-and time-dependent increase in subsequent neutrophil adherence (7 +/- 1% adherence to untreated HEC vs 38 +/- 3% adherence to HEC pretreated for 4 hr with LPS 150 ng/ml; mean +/- SE of 22 experiments: p less than 0.001). This effect was observed in primary and passaged HEC, but not in bovine aortic endothelial cells or human dermal fibroblasts. The LPS-induced activity appeared to be associated with the HEC surface, since it was not removed by washing and was not detected in the supernatant medium. Inhibition of RNA or protein synthesis during pretreatment of HEC with LPS prevented induction of the adherence-promoting activity. Pretreatment of HEC with IL 1 and rTNF-alpha produced a similar protein synthesis-dependent increase in neutrophil adherence to HEC. Coincubation of neutrophils with murine monoclonal antibody (MoAb) 60.3, an antibody directed to the CDw18 complex, produced a 70 +/- 4% inhibition of neutrophil adherence to LPS-pretreated HEC, 59 +/- 5% inhibition of adherence to IL 1-pretreated HEC, and 65 +/- 11% inhibition of adherence to rTNF-alpha-pretreated HEC (means +/- SE of 18, seven, and five experiments, respectively). Notably, MoAb 60.3 did not completely inhibit neutrophil adherence to pretreated HEC, although it completely inhibited adherence to untreated HEC when neutrophils were activated directly with phorbol ester. Similarly, the adherence of neutrophils from a patient with an inherited deficiency of the CDw18 complex to LPS-, IL 1-, and rTNF-alpha-pretreated HEC was markedly reduced compared with normal neutrophils (5 to 11% adherence with CDw18-deficient neutrophils vs 43 to 54% adherence with normal neutrophils), but adherence to pretreated HEC was still significantly greater than adherence to HEC that were not pretreated (2% adherence). We conclude that LPS, IL 1, and rTNF-alpha induce synthesis of an endothelial cell-surface factor(s) that promotes neutrophil adherence primarily by a mechanism involving the CDw18 complex. It thus appears that the CDw18 complex is important for augmented neutrophil adherence to endothelium in vitro whether the is stimulated directly by inflammatory mediators or indirectly by endothelial-dependent mechanisms.

Animals↗
PubMed1977

Neutrophil antigens: immunology and clinical implications.

Neutrophil antigens may be classified into two major categories: antigens shared with other cells and antigens specific for neutrophils. The first category includes the ABH, I, i, 5a,b and HLA determinants. Additional antigens with special characteristics in this category are the blood-group U, Kx, JkaJkb, and Ge determinants which apparently neutrophils share only with erythrocytes. Neutrophil-specific antigens include the NA1, NA2, NB1 and 9a. These specificities are detected by the agglutination test and have been shown to be present on mature neutrophils. Independent allospecificities, detectable by the granulocytotoxicity test, may also exist. In addition, neutrophil antigens, which are species-specific, have been identified by the use of xenogeneic antibodies. The EDTA-dependent agglutination test remains a most reliable assay for the study of neutrophil-specific antigens. The lack of reproducibility known in the leukoagglutination reaction does not pertain to the modification used in the assay of neutrophil-specific antibodies. It does apply, however, to those tests that were performed in the absence of EDTA, and in connection to the study of HLA-related antigens. For every pathophysiological state involving the erythrocyte antigens a neutrophil analogue is observed, the difference being in symptomatology which is related to the structural and functional characteristics of the cells: febrile and pulmonary transfusion reactions result from incompatibility neutrophils. It is found that similarity in the HLA antigens and nonreactivity in the MLC test do not preclude immunization against neutrophil-specific antigens. Therefore, it is probable that febrile and pulmonary reactions will occur in the recipients of multiple granulocyte transfusions, even though donors and recipients may be considered "histocompatible" by the HLA assays. It has been shown that fetal-maternal incompatibility can cause neonatal neutropenia, and several forms of autoimmune neutropenia are described: in "idiopathic" neutropenia of infancy, autoantibodies have been found to have specificity against NA1 and NA2 and in one adult, autoimmune neutropenia due to anti-NA1 antibody has been observed. Neutropenia also occurs due to idiopathic, cold-reacting antileukocyte antibodies, and with cold agglutinins associated with lymphoma, infectious mononucleosis, and Mycoplasma pneumonia. Although the role of neutrophil antigens in bone marrow transplantation has not as yet been determined, these antigens are undoubtedly immunogenic and potentially play an important role in neutrophil compatibility. It is obvious that neutrophils cannot survive in the presence of antineutrophil antibodies.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2003

Increased expression of surface activation markers on neutrophils following migration into the nasal lumen.

BACKGROUND: The sequence of events following the recruitment of a free-flowing neutrophil in the peripheral circulation, via adhesion, migration and release of mediators, to a neutrophil on the surface of the nasal epithelium is a co-ordinated process. Little is known about the state of neutrophil activation following this course of events. OBJECTIVES: To investigate the expression of surface activation markers on neutrophils, reflecting activation during their recruitment to the nose, and to see whether the inflammatory process during allergic rhinitis influences this process. METHOD: Nine healthy controls and 12 patients with grass pollen-induced intermittent allergic rhinitis were investigated during the peak of the pollen season. The expression of CD11b, CD66b and CD63 on the neutrophil cell surface, as a reflection of activation, was analysed using flow cytometry. Neutrophils were derived from peripheral blood and nasal lavage fluid. In addition, eosinophil cationic protein (ECP) and myeloperoxidase (MPO) as well as L-, P- and E-selectins in the nasal lavage fluid were analysed using RIA and ELISA, respectively. RESULTS: A marked increase in the expression of all three CD markers on the neutrophil cell surface was noticed following migration from the bloodstream to the surface of the nasal mucosa. At the peak of the grass pollen season, the MPO levels increased, reflecting an increase in the total number of nasal fluid neutrophils. In parallel, the expression of CD11b was further augmented. The expression of the CDb11b was reduced on neutrophils remaining in the circulation. In addition, the level of L-selectin was reduced on neutrophils derived from the blood during allergic inflammation. CONCLUSION: Neutrophils might become activated during their transfer from the blood to the surface of the nasal mucosa, but these changes may also be due to depletion of activated neutrophils in the blood via activated endothelial/epithelial adhesion and chemoattractant measures. The increased expression of surface activation markers during allergic rhinitis suggests roles for neutrophils in the inflammatory process.

Adult↗
PubMed2005

Downmodulation of CXCL8/IL-8 receptors on neutrophils after recruitment in the airways.

BACKGROUND: CXCL8/IL-8 is the most significant chemokine for neutrophils, and CXC chemokine receptor (CXCR) 1 and 2 are its 2 receptors, which are downmodulated by CXCL8/IL-8 and endotoxin on activated neutrophils. OBJECTIVE: We sought to evaluate the expression of the CXCL8/IL-8 receptors and the activation marker CD11b on neutrophils in peripheral blood and in the site of airway inflammation. METHODS: The flow cytometric expression of CXCR1, CXCR2, and CD11b was evaluated on peripheral blood and induced sputum neutrophils in patients with nonsevere asthma with greater than 60% sputum neutrophils, in patients with chronic obstructive pulmonary disease (COPD), and in healthy control subjects. RESULTS: Asthmatic patients and patients with COPD had comparable expressions of CXCR1, CXCR2, and CD11b on peripheral blood and sputum neutrophils. Compared with control subjects, the peripheral neutrophil expression of CXCR2 was lower in patients with COPD ( P = .03) and that of CD11b was higher in asthmatic patients and patients with COPD ( P < .02 and P < .002). The expression of the CXCL8/IL-8 receptors on sputum neutrophils was markedly lower than on peripheral blood neutrophils ( P < .0001). The downmodulation of CXCL8/IL-8 receptors was also present in healthy control subjects but less than that seen in asthmatic patients. The difference between peripheral blood and sputum expression of CXCL8/IL-8 receptors correlated with serum CXCL8/IL-8 levels. In asthmatic patients the expression of CXCR1 and CXCR2 on sputum neutrophils negatively correlated with sputum neutrophils. CONCLUSION: In neutrophilic asthma the expression of CXCL8/IL-8 receptors on peripheral and sputum neutrophils is similar to COPD and negatively correlated with the inflammatory infiltrate in the airways. The downmodulation of CXCL8/IL-8 receptors detected in the airways should be taken into account for an eventual therapeutic inhibition of these receptors.

Adolescent↗
PubMed2005

Neutrophils activation can be diminished by apolipoprotein A-I.

High density lipoprotein (HDL) has anti-inflammatory function. To investigate the effects of apolipoprotein A-I (ApoA-I), the major apolipoprotein of HDL, on activated neutrophils, we stimulated neutrophils in vitro with fMLP and PMA, as a receptor-binding and a nonreceptor-binding stimuli, respectively, and incubated ApoA-I with those neutrophils. Three conditions were utilized: 1) resting neutrophils + ApoA-I (0, 2.5,5, 10 microg/mL respectively), 2) fMLP(10(-7) mol/L)-activated neutrophils + ApoA-I (0, 2.5, 5, 10 microg/mL respectively), and 3) PMA(10(-7) mol/L)-activated neutrophils + ApoA-I (0, 2.5, 5, 10 microg/mL respectively). After incubation, we measured neutrophils adhesion to fibronectin, oxidative bust (O2- and H2O2 production), degranulation (release of MPO and elastase), and L929 cell mortality which were attacked by release-out of cytokines in activated neutrophils (using MTT). Our results showed that in vitro ApoA-I inhibits fMLP- and PMA- activated neutrophil adhesion, oxidative burst, degranulation and L929 cell mortality. These inhibition effects of ApoA-I on fMLP-activated neutrophils are more powerful than that on PMA-activated neutrophils. ApoA-I has no effect on resting neutrophils. We concluded that ApoA-I could diminish the function of activated neutrophils.

Acute-Phase Reaction↗
PubMed2004

The role of interleukin-1beta in direct and toll-like receptor 4-mediated neutrophil activation and survival.

The regulation of systemic and local neutrophil activation is crucial to the clearance of infections and the successful resolution of inflammation without progress to tissue damage or disseminated inflammatory reactions. Using purified lipopolysaccharide (pLPS) and highly purified neutrophils, we have previously shown that Toll-like receptor 4 signaling is a potent neutrophil activator, but a poor stimulator of survival. In the presence of peripheral blood mononuclear cells (PBMCs), however, pLPS becomes a potent neutrophil survival factor. Interleukin (IL)-1beta has been identified as an important neutrophil activator and prosurvival cytokine, and is produced in abundance by LPS-stimulated PBMCs. We now show that IL-1beta fails to activate highly purified neutrophils or enhance their survival, but in the presence of PBMCs, IL-1beta induces neutrophil survival. We hypothesized that LPS-primed neutrophils might become responsive to IL-1beta, but were unable to demonstrate this. Moreover, IL-1ra failed to prevent pLPS + PBMC-dependent neutrophil survival. In studies of IL-1R1(-/-) mice, we found that LPS was still able to mediate neutrophil survival, and neutrophil survival was enhanced by the addition of monocytic cells. Thus an important paradigm of neutrophil regulation needs to be viewed in the context of a cellular network in which actions of IL-1beta on neutrophils are indirect and mediated by other cells.

Animals↗
PubMed2002

Neutrophil-mediated tissue injury in alcoholic hepatitis.

The presence of polymorphonuclear leukocytes (neutrophils) in liver parenchyma is a prominent feature of alcoholic hepatitis. However, the pathophysiological importance of these phagocytes and potential injury mechanisms in alcoholic hepatitis remain unclear. This review summarizes the current knowledge on basic mechanisms of neutrophil-induced liver injury as it emerged from studying a number of different experimental models. This general concept of neutrophil-mediated liver cell injury agrees with many observations made by examining liver sections obtained from patients with alcoholic hepatitis. These include the presence of extravasated neutrophils in the liver, evidence for degranulation of neutrophils in the parenchyma, and excessive formation of neutrophil chemoattractants such as CXC chemokines in liver cells. Colocalization and a strong quantitative correlation between apoptotic hepatocytes and neutrophils could indicate apoptosis-induced transmigration of neutrophils during alcoholic hepatitis, similar to events previously demonstrated in experimental models. Furthermore, circulating neutrophils are primed for reactive oxygen species and inflammatory mediator formation. However, clear evidence for a neutrophil-induced injury in alcoholic hepatitis is missing. Unfortunately, most experimental models of alcoholic liver disease do not have a prominent neutrophilic infiltrate. Therefore, a high priority of future research has to be to develop an experimental model that realistically mimics the neutrophil component of alcoholic hepatitis in human beings. This would allow investigators to test the concept that neutrophils are important for cell injury during alcoholic hepatitis and to identify potential therapeutic intervention strategies.

Animals↗
PubMedDate not supplied

The effects of sarpogrelate on superoxide production by human neutrophils.

BACKGROUND AND OBJECTIVES: Superoxide anion (O2-) released from neutrophils plays an important role in antibacterial host defense system and tissue auto-injury. Sarpogrelate, a serotonin-receptor antagonist, has been successfully used for management of chronic pain caused by arterial occlusive or ischemic vascular diseases, or by microcirculation disturbances. Suppression of O2- generation may be detrimental to infection or contribute to the therapeutic approach to these diseases, the pathogenesis of which probably includes neutrophil activation. No data regarding the effects of sarpogrelate on neutrophil functions are available despite the possible clinical concern. The purpose of this study was to determine whether sarpogrelate reduces O2- production by human neutrophils using an in vitro system. In addition, we examined changes in concentrations of the intracellular calcium ion ([Ca2+]i), which is responsible for one of the mechanisms of the neutrophils' O2- production. METHODS: The O2- production by human neutrophils or the xanthine-xanthine oxidase system and [Ca2+]i were measured in the absence and the presence (at clinically relevant concentrations: 0.1x, 10x, and 100x these concentrations) of sarpogrelate. RESULTS: Sarpogrelate inhibited O2- production of neutrophils in a dose-dependent manner. The drug at a clinically relevant concentration suppressed this neutrophil function. In contrast, sarpogrelate failed to inhibit O2-generation by the cell-free (xanthine-xanthine oxidase) system. Elevation of [Ca2+]i in neutrophils stimulated by a chemotactic factor was dose-dependently attenuated with sarpogrelate. CONCLUSIONS: These findings suggest that sarpogrelate (even at clinically relevant concentrations) is able to inhibit O2- production by neutrophils. However, the drug failed to quench an excessive amount of O2- (similar to the level produced by neutrophils). There is a possibility that the inhibitory effect of the drug on [Ca2+]i response in neutrophils may contribute to impairment of the neutrophils' O2- production. Further studies using in vivo systems are required to elucidate the inhibitory effects of sarpogrelate on O2- in clinical settings.

Calcium↗
PubMed2003

Enteropathogenic Escherichia coli: stimulating neutrophil migration across a cultured intestinal epithelium without altering transepithelial conductance.

INTRODUCTION: Migration of neutrophils across the intestinal epithelium is the hallmark of inflammatory conditions of the bowel. In cultured intestinal epithelial monolayer models, neutrophils can be induced to migrate along a chemotactic gradient such as n-formyl-methionyl-leucyl-phenylalanine (fMLP). Physical passage of the neutrophils across the epithelium could disrupt the tight-junctions, possibly leading to a large increase in the transepithelial conductance (G(t)). The goal of this study is to determine whether transepithelial migration of neutrophils induced by enteropathogenic (EPEC) causes changes in G(t) comparable with those seen with fMLP. METHODS: The apical side of T84 monolayers were rapidly infected with EPEC E2348/69 or exposed to 1 microM fMLP. A third group of monolayers exposed to neither EPEC nor fMLP served as control. Indium-labeled neutrophils were added to the serosal side of monolayers grown on a cell culture insert membrane (12 microm pores). G(t) was measured at fixed intervals up to 4 hours. After a 150-minute incubation, radioactivity of the neutrophils that migrated to the apical side was assayed and the number of migrating neutrophils was calculated. RESULTS: At 150 minutes, EPEC induced similar neutrophil chemotactic capability compared to fMLP (231 +/- 34.10(3) and 193 +/- 48.10(3), respectively, n = 13, P > 0.05). However, EPEC-induced neutrophil migration was not associated with significant increase in G(t), 1.13 +/- 0.16 fold of baseline G(t), in distinction with fMLP groups, 13.3 +/- 0.48 fold, n = 7 (P< 0.05). G(t) changes with EPEC were seen after 4 hours of infection, but were not different in the presence or absence of neutrophil migration (1.37 +/- 0.12 fold and 1.42 +/- 0.17 fold of baseline G(t), respectively). CONCLUSIONS: The results indicate that EPEC-induced neutrophil migration can occur without significant disruption of barrier function. In addition, the chemo-attractant recruiting neutrophils during EPEC infection is unlikely to be fMLP; and, the G(t) increase seen with fMLP-driven recruitment may indicate a discretionary compromise of barrier function during neutrophil migration.

Bacterial Adhesion↗
PubMed2004

Beneficial effects of troglitazone on neutrophil dysfunction in multiple low-dose streptozotocin-induced diabetic mice.

Patients with poorly controlled diabetes are at high risk of acquiring bacterial infections. However, conflicting results have been reported on neutrophil function in diabetes. We periodically evaluated neutrophil dysfunction in multiple low-dose streptozotocin (STZ)-induced diabetic mice, and then evaluated the effects of troglitazone and other thiazolidinediones (TZDs) on the decline of neutrophil function. Zymosan was injected intraperitoneally and neutrophil infiltration and phagocytosis were evaluated. While phagocytosis of zymosan by peritoneal neutrophils was consistently reduced in diabetic mice, neutrophil infiltration was decreased on day 30, but increased on day 40 after STZ injection. The in vitro chemotactic and phagocytic activities of blood neutrophils in mice that did not receive zymosan were consistently reduced in diabetic mice. Phorbol myristate acetate (PMA)-stimulated superoxide production by zymosan-induced peritoneal neutrophils and the levels of zymosan-induced tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta in peritoneal exudate fluids were also reduced in the diabetic mice. Treatment of the diabetic mice with troglitazone beginning 2 weeks after STZ injection did not improve hyperglycaemia but did prevent the decline of zymosan-induced neutrophil infiltration on day 30, and additionally promoted the increased infiltration on day 40. Troglitazone also promoted the chemotactic activity of blood neutrophils isolated from normal mice in vitro. Rosiglitazone but not pioglitazone induced a similar effect. Neutrophil phagocytosis was not enhanced by troglitazone either in vivo or in vitro. Taken together, neutrophil function is impaired by STZ-induced diabetes, but inflammatory infiltration does not always vary with the chemotactic disability or cytokine levels. Furthermore, troglitazone and rosiglitazone were suggested to improve at least neutrophil chemotactic activity in these animals.

Animals↗
PubMed2004

Decreased apoptosis of beta 2- integrin-deficient bovine neutrophils.

Stimulant-induced viability of neutrophils, nuclear-fragmentation, increase in intracellular calcium ([Ca2+]i), expression of annexin V on neutrophils and proteolysis of a fluorogenic peptide substrate Ac-DEVD-MCA (acetyl Asp-Glu-Val-Asp alpha-[4-methyl-coumaryl-7-amide]) by neutrophil lysates from five normal calves and three calves with leucocyte adhesion deficiency were determined to evaluate the apoptosis of normal and CD18-deficient neutrophils. Viability was markedly decreased in control neutrophils stimulated with opsonized zymosan (OPZ), compared to CD18-deficient neutrophils at 37 degrees C after incubation periods of 6 and 24 hours. The rate of apoptosis of control neutrophils stimulated with OPZ increased significantly depending on the incubation time, whereas no apparent increase in apoptosis was found in CD18-deficient neutrophils under the same conditions. Aggregated bovine (Agg) IgG-induced apoptosis of control neutrophils was not significantly different from that of CD18-deficient neutrophils. The expression of annexin V on OPZ-stimulated control neutrophils was greater than that of unstimulated ones 6 h after stimulation. No apparent increase in annexin V expression on CD18-deficient neutrophils was found with OPZ stimulation. A delay in apoptosis was demonstrated in CD18-deficient bovine neutrophils and this appeared to be closely associated with lowered signalling via [Ca2+]i, diminished annexin V expression on the cell surface, and decreased caspase 3 activity in lysates.

Animals↗