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E Brandt

Publications and source records attributed to E Brandt.

At least 37 records · Page 2Linked to original sources
PubMed2000

IL-4 production by human polymorphonuclear neutrophils.

Polymorphonuclear neutrophils (PMN) are phagocytic cells, able to secrete a large range of cytokines, including inflammatory cytokines, chemokines, as well as the Th1 cytokines interferon-gamma (IFN-gamma) and interleukin (IL)-12. Although PMN do not seem to express IL-10 and IL-13, no information exists on the ability of PMN to produce IL-4. Therefore intracellular flow cytometry was performed in the presence or absence of Brefeldin A. Similarly to eosinophils, freshly isolated neutrophils from normal donors contained low amounts of IL-4, which significantly increased upon culture with Brefeldin A (P < 0001). Immunostaining performed on cytospin preparations of normal granulocytes confirmed the presence of intracellular IL-4. Using a highly sensitive ELISA, the levels of IL-4 secreted by cultured PMN and peripheral blood mononuclear cells (PBMC) were compared. PBMC secrete up to 60 times more IL-4 as PMN but, in the presence of calcium ionophore, only PMN showed a slight but significant increase in IL-4 secretion (P < 0.05). In conclusion, we report here the presence within human PMN of intracellular IL-4, which can at least partly be released under calcium ionophore stimulation. The relevance of this production of IL-4 by human PMN is discussed.

Brefeldin A↗
PubMed1999

Platelet factor 4-induced neutrophil-endothelial cell interaction: involvement of mechanisms and functional consequences different from those elicited by interleukin-8.

Platelet factor 4 (PF-4), a member of the CXC-subfamily of chemokines, is secreted in high amounts by activated platelets. In previous studies, we found that PF-4 specifically binds to human polymorphonuclear granulocytes (PMN), but requires tumor necrosis factor-alpha (TNF-alpha) as a costimulus for the induction of effector functions in suspended cells. In the present study, we have examined PF-4 in comparison with interleukin-8 (IL-8) for its ability to promote interaction of PMN with cultured endothelial cells (EC). We show here for the first time that PF-4 dose-dependently induces PMN to undergo extremely firm adhesion to EC as well as to exocytose secondary granule contents in the presence of these cells. Interestingly, costimulation by TNF-alpha was not required, indicating that EC could provide a corresponding signal(s). As evident from antibody blocking experiments, PF-4-induced adhesion involved PMN-expressed L-selectin as well as leukocyte function-associated molecule-1 (LFA-1), whereas IL-8 involved MAC-1. Because blocking antibodies to LFA-1 but not to L-selectin or MAC-1 abrogated PF-4-dependent marker exocytosis from PMN, the costimulatory signal provided by EC appears to be elicited through cell-cell contact via LFA-1. IL-8, inducing the upregulation of MAC-1, did not elicit marker exocytosis in contact with EC. Our results suggest a role for PF-4 in the promotion of PMN-EC interaction that is virtually different from that exhibited by other CXC-chemokines such as IL-8.

Cell Adhesion↗
PubMed1999

Characterization of a neutrophil cell surface glycosaminoglycan that mediates binding of platelet factor 4.

Platelet factor 4 (PF-4) is a platelet-derived alpha-chemokine that binds to and activates human neutrophils to undergo specific functions like exocytosis or adhesion. PF-4 binding has been shown to be independent of interleukin-8 receptors and could be inhibited by soluble chondroitin sulfate type glycosaminoglycans or by pretreatment of cells with chondroitinase ABC. Here we present evidence that surface-expressed neutrophil glycosaminoglycans are of chondroitin sulfate type and that this species binds to the tetrameric form of PF-4. The glycosaminoglycans consist of a single type of chain with an average molecular mass of approximately 23 kDa and are composed of approximately 85-90% chondroitin 4-sulfate disaccharide units type CSA (-->4GlcAbeta1-->3GalNAc(4-O-sulfate)beta1-->) and of approximately 10-15% di-O-sulfated disaccharide units. A major part of these di-O-sulfated disaccharide units are CSE units (-->4GlcAbeta1-->3GalNAc(4,6-O-sulfate)beta1-->). Binding studies revealed that the interaction of chondroitin sulfate with PF-4 required at least 20 monosaccharide units for significant binding. The di-O-sulfated disaccharide units in neutrophil glycosaminoglycans clearly promoted the affinity to PF-4, which showed a Kd approximately 0.8 microM, as the affinities of bovine cartilage chondroitin sulfate A, porcine skin dermatan sulfate, or bovine cartilage chondroitin sulfate C, all consisting exclusively of monosulfated disaccharide units, were found to be 3-5-fold lower. Taken together, our data indicate that chondroitin sulfate chains function as physiologically relevant binding sites for PF-4 on neutrophils and that the affinity of these chains for PF-4 is controlled by their degree of sulfation.

Animals↗
PubMed1999

Chemokines and chemokine receptors: their role in allergic airway disease.

One of the hallmarks of allergic pulmonary disorders is the accumulation of an abnormally large number of leukocytes including eosinophils, neutrophils, lymphocytes, basophils, and macrophages in the lung. There is now substantial evidence that eosinophils, under the control of T lymphocytes, are major effector cells in the pathogenesis of asthma. Therefore, understanding the mechanisms by which eosinophils accumulate and are activated in tissues is a fundamental question very relevant to allergic diseases. Another characteristic of allergic inflammation is the activation of leukocytes resulting in the release of biologically active mediators, such as histamine from mast cells and basophils. It is now apparent that chemokines are potent leukocyte chemoattractants, cellular activating factors, histamine releasing factors, and regulators of homeostatic immunity, making them particularly important in the pathogenesis of airway inflammation in asthma. In this regard, chemokines are attractive new therapeutic targets for the treatment of allergic disease. This article focuses on recently emerging data on the importance of chemokines and their receptors in allergic airway inflammation.

Animals↗
PubMed1999

The role of cytokines in monocyte apoptosis.

Survival or apoptosis, activation and differentiation, phagocytosis and antigen presentation, migration or participation in granuloma formation are features of freshly recruited blood-borne monocytes in the local environment. In this presentation we describe that human monocytes undergo spontaneous apoptosis in vitro which involves Fas/FasL interactions, and that proinflammatory cytokines such as tumor necrosis factor-alpha (TNFalpha), interleukin-1beta and granulocyte-monocyte-colony-stimulating factor prevent spontaneous apoptosis. In vitro infection of purified monocytes with low numbers of Mycobacterium tuberculosis H37Rv prevents spontaneous apoptosis. The apoptosis-preventing effect is correlated to the release of TNFalpha and not due to phagocytosis per se. Furthermore, the minor subset of CD64-negative monocytes is found to be less susceptible to recall antigen-activated CD4-positive T cell-mediated apoptosis than CD64-positive monocytes. Finally, recent findings of our group indicate that the chemokine platelet factor 4 protects monocytes from spontaneous apoptosis and induces the differentiation of monocytes into macrophages. From these findings we conclude that monocyte recruitment, their survival, their differentiation and their functional activity at the site of inflammation are regulated by a cytokine network which needs to be further analyzed in order to design strategies for immune intervention.

Antibodies, Bacterial↗
PubMed1998

Novel C-terminally truncated isoforms of the CXC chemokine beta-thromboglobulin and their impact on neutrophil functions.

The neutrophil agonist neutrophil-activating peptide-2 (NAP-2) arises through proteolytic processing of platelet-derived N-terminally extended inactive precursors, the most abundant one being connective tissue-activating peptide-III (CTAP-III). Apart from N-terminal processing, C-terminal processing also appears to participate in the functional regulation of NAP-2, as indicated by our recent identification of an isoform missing four C-terminal amino acids, NAP-2 (1-66), which was about threefold more potent than full-size NAP-2. In the present study, we report on the discovery and identification of natural NAP-2 (1-63), an isoform truncated by seven C-terminal residues. Functional and receptor-binding analyses demonstrated that NAP-2 (1-63) represents the most active isoform, being about fivefold more potent than full-size NAP-2. Analyses of rNAP-2 isoforms successively truncated at the C terminus by up to eight residues suggest functionally important roles for acidic residues and for the leucine at position 63, a residue highly conserved within CXC chemokines. Finally, we report on a novel C-terminally truncated isoform of CTAP-III (CTAP-III (1-81)) representing the potential precursor of NAP-2 (1-66). We show that C-terminal truncation in CTAP-III enhances its potency to desensitize chemokine-induced neutrophil activation, indicating that C-terminal processing might not only serve to enhance neutrophil activation, but might as well participate in the down-regulation of an inflammatory response.

Blood Coagulation Factors↗
PubMed1998

A chondroitin sulfate proteoglycan on human neutrophils specifically binds platelet factor 4 and is involved in cell activation.

Platelet factor 4 (PF-4), a member of the alpha-chemokine subfamily of cytokines, activates human neutrophils independently of intracellular free calcium mobilization or binding to IL-8R. In the present study, we have identified and partially characterized a receptor for PF-4 on human neutrophils, which displays weak cross-reactivity with the IFN-gamma-inducible protein 10, but not with other alpha-chemokines such as IL-8, neutrophil-activating peptide 2, or melanoma growth-stimulatory activity (GRO alpha). Binding studies revealed that human neutrophils express a high number of receptors (Bmax approximately 7.6 x 10(6) sites/cell) of moderate affinity (Kd approximately 650 nM). The kinetics of PF-4-binding correlates with the proportion of PF-4 tetramers in solution and with the activation of neutrophils for exocytosis. Reduction of PF-4 binding and PF-4-induced exocytosis in the presence of various glycosaminoglycans or following treatment of cells with chondroitinase ABC (but not other glycosaminoglycan-degrading enzymes) altogether demonstrates that the PF-4 receptor is a proteoglycan of the chondroitin sulfate class. Cross-linking experiments with radiolabeled PF-4 revealed a receptor-ligand complex of approximately 250 kDa. Taken together, our data show that a distinct chondroitin sulfate proteoglycan represents specific receptors for tetrameric PF-4 on human neutrophils.

Cells, Cultured↗
PubMed1998

Platelet-derived interleukin-1 induces cytokine production, but not proliferation of human vascular smooth muscle cells.

During vascular injury, such as observed in atherosclerosis, restenosis, vasculitides, transplantation, or sepsis, vascular smooth muscle cells (SMC) can be exposed to platelets or platelet products. Under these conditions proliferation or cytokine production of SMC stimulated by platelets or platelet products may contribute to regulation of vascular pathogenesis. Thus, we investigated interleukin-6 (IL-6) and IL-8 production as well as proliferation of SMC in response to platelets or platelet lysates. Platelets not already preactivated by thrombin induced IL-6 (10- to 50-fold) or IL-8 production of unstimulated SMC in a cell number dependent fashion. Preactivation of platelets with thrombin potently increased the platelet-mediated IL-6 (50- to 1,000-fold) and IL-8 production of SMC. Hirudin specifically inhibited the activation of platelets with thrombin. Isolated platelets cultured in the absence of SMC did not contain detectable IL-6 or IL-8. Prestimulation (4 hours) of SMC with pathophysiologically relevant substances (lipopolysaccharide [LPS], tumor necrosis factor-alpha [TNF-alpha], or IL-1alpha) further increased the platelet-induced cytokine production. The platelet-derived SMC stimulatory activity was IL-1, since IL-1 receptor antagonist (IL-1-Ra) inhibited the platelet-induced cytokine production of SMC. Anti-platelet-derived growth factor (PDGF)-antibody did not further reduce this activity. Thrombin itself stimulated expression of IL-6 and IL-8 to some degree and induced IL-6 production of SMC synergistically with IL-1. Platelets also induced proliferation of SMC, however, anti-PDGF antibodies, rather than IL-1-Ra blocked this response. These data show that platelet-derived IL-1 stimulates cytokine production of vascular smooth muscle cells, indicating that platelet-derived IL-1 may contribute to regulation of local pathogenesis in the vessel wall by activation of the cytokine regulatory network.

Antibodies, Monoclonal↗
PubMed1998

Circulating growth-regulator oncogene alpha contributes to neutrophil priming and interleukin-8-directed mucosal recruitment into chronic lesions of patients with Crohn's disease.

Crohn's disease (CD) lesions are characterized by a marked neutrophilic infiltrate associated with enhanced mucosal IL-8, contrasting with low serum IL-8 levels. The aim of this study was to investigate the effects of circulating GROalpha and IL-8 on neutrophil priming and migration. The expression of surface molecules involved in rolling (CD62L, CD15) and firm adhesion (Mac-1 and LFA-1) to endothelial cells was assessed by flow cytometry, while the chemotactic response of PMN to IL-8 and to fMLP was investigated in a Boyden chamber assay. In addition, IL-8 and GROalpha levels were determined by ELISA in plasma samples and in culture supernatants of purified polymorphonuclear neutrophils (PMN) and peripheral blood mononuclear cells (PBMC) from patients with CD and healthy blood donors. This study revealed an upregulation of CD11b (Mac-1) membrane expression on circulating PMN from patients with CD, as assessed by the mean fluorescence intensity which reflects antigen density. Furthermore, an enhanced chemotactic response towards both fMLP and IL-8 of PMN from CD patients was observed. Despite often undetectable levels of circulating IL-8, all plasma samples were positive for GROalpha, with a significant increase in CD patients when compared to donors. In vitro, equivalent concentrations of GROalpha were able to increase the IL-8 driven chemotaxis of PMN. In conclusion, blood PMN from patients with CD showed an enhanced capacity to be recruited into inflammed intestinal mucosa, which could be due to an increased expression of CD11b (Mac-1) as well as an increased chemotactic response toward fMLP or IL-8. This priming effect of PMN in CD may partly occur through elevated circulating GROalpha levels.

Case-Control Studies↗
PubMed1997

The CXC-chemokine neutrophil-activating peptide-2 induces two distinct optima of neutrophil chemotaxis by differential interaction with interleukin-8 receptors CXCR-1 and CXCR-2.

The CXC-chemokines interleukin-8 (IL-8), neutrophil-activating peptide-2 (NAP-2), and melanoma growth-stimulatory activity (MGSA) are chemoattractants with high selectivity for neutrophils. Although IL-8 has been shown to act as an extremely potent mediator, reports on NAP-2 and MGSA are still contradictory. Here we show for the first time that NAP-2 and MGSA induce two distinct optima of neutrophil chemotaxis. A first optimum is elicited within a concentration range as low as it is characteristic for IL-8. However, a second optimum appears at more than 200-fold higher stimulus concentrations, at which IL-8 is inactive. Investigating the involvement of the two chemokine receptors CXCR-1 and CXCR-2 in NAP-2-mediated chemotaxis, we observe that the cells become desensitized to the first optimum of the chemokine after selective downregulation of CXCR-2, while both optima disappear upon simultaneous downregulation of both receptors. Blocking monoclonal antibodies (MoAbs) specific for CXCR-2 or CXCR-1 either suppress the first optimum of NAP-2-induced chemotaxis or drastically reduce the second one, respectively. These results provide evidence that both receptors are involved in NAP-2-induced neutrophil chemotaxis, with CXCR-2 rendering the cells responsive to low dosages of the chemokine, and with CXCR-1 extending their responsiveness to NAP-2 dosages higher by several orders of magnitude.

Antibodies, Monoclonal↗
PubMed1997

Mycobacterium bovis Bacillus Calmette Guérin infection prevents apoptosis of resting human monocytes.

Apoptosis plays an essential role in the development and homeostasis of multicellular organisms. Some infectious agents interfere with this programmed cell death to their own benefit. Here, we show that infection of resting human monocytes with Mycobacterium bovis Bacillus Calmette Guérin (BCG) increases monocyte viability by preventing them from undergoing apoptosis. Heat-killed BCG also prevented apoptosis, indicating that replication of BCG is not required to prevent cell death. Analysis of BCG-infected monocytes revealed an up-regulation of the A1 mRNA, whereas the bcl-2 mRNA was not up-regulated. Interestingly, preinfection with BCG renders the cells resistant to interleukin (IL)-10-induced apoptosis which may be one of the mechanisms mycobacteria use to modulate immune responses. BCG infection was also accompanied by an impairment of the capacity of monocytes to secrete IL-10 and by an induction of the capacity to secrete tumor necrosis factor-alpha, two cytokines known to induce and prevent human monocyte apoptosis, respectively. Since it has been reported that apoptosis is involved in killing of intracellular mycobacteria, the prevention of apoptosis may represent a strategy for mycobacterial survival in the infected host.

Apoptosis↗
PubMed1997

Distinct cytokine patterns in early and chronic ileal lesions of Crohn's disease.

BACKGROUND & AIMS: Chronic intestinal lesions of patients with Crohn's disease (CD) are associated with a T helper (Th) 1-type cytokine profile, including high levels of interleukin 2 (IL-2) and interferon gamma (IFN-gamma). However, the mechanisms involved in the pathogenesis of the early mucosal lesions are poorly known. The aim of this study was to examine the pattern of Th1- and Th2-type (IL-4, IL-5, and IL-13) cytokines in the early ileal lesions occurring in patients with CD 3 months after ileal resection and ileocolonic anastomosis. Cytokines were also examined in the chronic ileal lesions to look for cytokine patterns related to disease progression. METHODS: Ileal biopsy specimens were obtained from 17 patients with CD and 11 controls. Mucosal IL-2, IFN-gamma, IL-4, IL-5, and IL-13 messenger RNA (mRNA) was evaluated by competitive reverse-transcription polymerase chain reaction. RESULTS: The early ileal lesions of patients with CD were associated with a significant increase of IL-4 mRNA and a decrease of IFN-gamma mRNA compared with the normal mucosa of patients with CD or controls. A Th1-type pattern was observed in the chronic ileal lesions. CONCLUSIONS: Divergent cytokine patterns are observed during different clinical stages of CD. These observations need to be considered in the development of newer specific therapeutic agents to prevent CD recurrences.

Adult↗
PubMed1996

[Olympic games 1994 and the Medical Department, Lillehammer county hospital].

Lillehammer is a town with almost 24,000 inhabitants. During the 16 days of the XVII Olympic Winter Games in February 1994, approximately 1.9 million spectators visited the area. The << extra >> population during that period, led to 50 people being admitted for treatment in the Medical Department at Lillehammer County Hospital, i.e. 2.6 per 100,000 spectators. The number of admissions of persons from the resident population was lower than during the same period in previous years.

Hospitals, County↗
PubMed1996

TNF-alpha renders human neutrophils responsive to platelet factor 4. Comparison of PF-4 and IL-8 reveals different activity profiles of the two chemokines.

Platelet factor 4 (PF-4), like IL-8, is a member of the chemokine superfamily of proinflammatory cytokines. However, although the capacity of IL-8 to stimulate functions in neutrophils is well established, reports on PF-4 are still contradictory. In the present study, we have prepared highly purified PF-4 and examined its ability to induce chemotaxis, degranulation, adhesion to gelatin and plasma proteins, and changes in intracellular calcium levels. Even over a broad range of concentrations, PF-4 alone was unable to induce functional changes in PMN. However, neutrophils pre- or co-incubated with physiologically relevant concentrations of TNF-alpha responded to PF-4 by the selective mobilization of the secondary granule marker lactoferrin but not of the primary granule marker elastase. Contrary to IL-8, PMN did not require pretreatment with cytochalasin B for PF-4-induced exocytosis of lactoferrin. The synergistic effect of PF-4 with TNF-alpha was not a priming phenomenon because the cooperative response remained unchanged even when TNF-alpha was added 5 min after the chemokine. In contrast, TNF-alpha-treated PMN did not respond to PF-4 by chemotaxis or by an increase of intracellular calcium levels, and no competition of PF-4 for IL-8 receptors was observed. Our results suggest a mechanism as well as a biologic role of PF-4 in the regulation of neutrophil function, which is different from that of IL-8 and other alpha-chemokines.

Biomarkers↗
PubMed1996

In vitro modulation of induced neutrophil activation by different surfactant preparations.

Endotracheal surfactant administration has gained an important role in the treatment of respiratory failure. Polymorphonuclear neutrophil granulocyte (PMN) activation mediated by chemoattractants, such as interleukin-8 (IL-8), neutrophil-activating peptide-2 (NAP-2) and formylated bacterial oligopeptides, has been found to be involved in the pathophysiology of acute respiratory failure. We investigated potential modulating effects of commercial surfactant preparations (Exosurf, Alveofact, Curosurf and Survanta) on spontaneous and chemoattractant-induced PMN function. Isolated cytochalasin B (CytB)-treated PMNs from healthy adults were incubated with increasing concentrations of surfactant. The response of the cells was measured in terms of elastase release from the lysosomes within 30 min. The PMNs showed no direct activation by any of the surfactants tested. However, when cells were stimulated with suboptimal dosages of chemokines, such as IL-8 (2 nM) or NAP-2 (100 nM), or formyl-methionyl-leucyl-phenylalanine (fMLP) (50 nM), and co-incubated with increasing concentrations of surfactant (0.05-8 mg.mL-1) the release of elastase was markedly modulated depending on the surfactant preparation used. Whilst Exosurf and Alveofact showed only modest effects on the elastase release induced by all three mediators, Curosurf and Survanta markedly inhibited the cellular response in a dose-dependent manner. At concentrations above 1 mg.mL-1, Curosurf and Survanta decreased the IL-8-, NAP-2- and fMLP-induced elastase release by 83, 67 and 90%, and by 82, 75 and 80%, respectively. In conclusion, exogenous surfactant may modulate the inflammatory response of the airways by affecting the chemoattractant-induced polymorphonuclear neutrophil activation. Surfactant preparations with inhibiting properties on neutrophil activation may participate in the prevention of neutrophil-induced lung damage.

Adult↗