Biomedical subjects

J G Elferink

Publications and source records attributed to J G Elferink.

At least 37 records · Page 2Linked to original sources

PubMed1997

The effect of sodium aurothiomalate on stimulated and non-stimulated migration by human neutrophils: the role of cyclic GMP.

Preincubation of human neutrophils with aurothiomalate had little effect on random migration or chemotactic migration towards the chemotactic peptide fMLP. However, a strong enhancement of migration was observed when aurothiomalate was present in a concentration gradient; the effect of the drug was chemotactic rather than chemokinetic. Thiomalate also caused a chemotactic enhancement of migration but here a tenfold higher concentration of the drug was required as compared with aurothiomalate. Aurothiomalate caused an increase of cellular cGMP level, and inhibitors of guanylate cyclase inhibited the activating effect of aurothiomalate. Three specific antagonists of cGMP-dependent kinase (G-kinase) strongly inhibited aurothiomalate-induced migration of electroporated neutrophils. The results suggest that stimulation of migration by aurothiomalate is mediated by cGMP and a G-kinase. Monoclonal anti-IL-8 inhibited aurothiomalate-induced stimulation of migration. Though no increased release of IL-8 could be established upon exposure of neutrophils to aurothiomalate, it seems conceivable that the stimulating effect of aurothiomalate is mediated by IL-8.

Cell Movement↗

PubMed1997

The stimulation of human neutrophil migration by angiotensin IL: its dependence on Ca2+ and the involvement of cyclic GMP.

1. Angiotensin II had a bimodal effect on human neutrophil migration. Low concentrations of angiotensin II stimulated random migration. At a concentration of 10(-10) M it caused a maximal increase of migration; migration increased from 47.2 +/- 2.1 microns in the absence of angiotensin II, to 73.1 +/- 2.2 microns with 10(-10) M angiotensin II present in the lower compartment of the Boyden chamber (n = 5, P < 0.001). Stimulation of migration by angiotensin II was partly chemotactic and partly chemokinetic. Angiotensin II concentrations of 10(-8) M and higher inhibited chemotactic peptide-stimulated chemotaxis. 2. The stimulant effect of angiotensin II on migration was completely dependent on extracellular Ca2+. In the presence of 1 mM Ca2+, angiotensin II stimulated migration to 76.1 +/- 1.7 microns, while migration in the absence of Ca2+ was 42.2 +/- 1.9 microns (n = 4, P < 0.001). Different types of calcium channel blockers either moderately or strongly inhibited angiotensin II-activated migration. Stimulation of migration by angiotensin II in intact cells required higher concentrations of Ca2+ than in electroporated cells. This supports the view that there is an influx of Ca2+ through the plasma membrane, and a requirement of calcium for an intracellular target. 3. Angiotensin II-stimulated migration was inhibited by pertussis toxin; from 71.6 +/- 2.0 microns in the absence, to 43.6 +/- 1.5 microns in the presence of pertussis toxin (n = 4, P < 0.001). Migration of electroporated neutrophils stimulated by angiotensin II was synergistically enhanced by GTP gamma S. This suggests that one or more G-proteins are involved in the activating effect of angiotensin II. 4. Inhibitors of soluble guanylate cyclase and antagonists of cyclic GMP-dependent kinase strongly inhibited the activating effect of angiotensin II. The results suggest that the activating effect of angiotensin II is mediated by cyclic GMP and by cyclic GMP-dependent kinase.

Angiotensin II↗

PubMed1996

Modulation of human neutrophil chemotaxis by the endothelin-B receptor agonist sarafotoxin S6c.

At low concentrations (4 x 10(-9) M) sarafotoxin S6c, a selective agonist of the ETB receptor, caused a slight but significant chemotactic enhancement of neutrophil migration. In contrast with stimulation by endothelins, stimulation of migration by sarafotoxin was only mediated by the ETB receptor because BQ123, a selective antagonist of the ETA receptor, had no effect on the enhancement. At higher concentrations (10(-8) M and higher) sarafotoxin inhibited neutrophil migration stimulated by chemotactic activators. It thus appears that the ETB receptor mediates the inhibition of migration by high concentrations of sarafotoxin. The degree of inhibition by sarafotoxin was dependent on the type of activator; especially IL-8 activated migration was strongly inhibited. Extracellular calcium had little effect on stimulation or inhibition by sarafotoxin, in contrast with endothelins. In a very small concentration range (4 x 10(-8) M) sarafotoxin caused an increase of cytoplasmic free calcium; higher concentrations of sarafotoxin had no effect on cytoplasmic calcium, nor did they affect calcium changes caused by fMet-Leu-Phe (fMLP). IRL1038, a selective antagonist of the ETB receptor, equally gave a small potentiation at low concentrations, and inhibited agonist-activated chemotaxis at higher concentrations, suggesting that occupation of the ETB receptor by either agonist or antagonist results in a modulation of migration.

Calcium↗

PubMed1996

Carbon monoxide enhances human neutrophil migration in a cyclic GMP-dependent way.

Carbon monoxide (CO) enhanced random migration of human neutrophils. An optimally stimulatory effect was observed with 10 microM CO. CO caused a rapid and transient increase in intracellular level of guanosine-3',5'-cyclic monophosphate (cGMP). The enhancing effect of CO on random migration was reversed to a large extent by inhibitors of cGMP accumulation, and by antagonists of cGMP-dependent protein kinase (G-kinase). These results strongly suggest that the enhancement of random migration by CO is mediated by cGMP and G-kinase. Using hemoglobin, a scavenger of CO, we could show that stimulation of soluble guanylate cyclase over an extended period of time, rather than the observed fast and transient increase in intracellular cGMP levels, is responsible for CO-activated migration. We postulate that CO, like nitric oxide (NO), acts as a biological signal in the immune system.

Aminoquinolines↗

PubMed1996

Modulation of neutrophil migration by exogenous gaseous nitric oxide.

We studied the effect of exogenous nitric oxide (NO) on migration of rabbit peritoneal neutrophils. Exogenous NO enhanced random migration of neutrophils in a concentration-dependent way. An optimally stimulatory effect was observed with 0.5 microM NO, whereas at higher NO concentrations the enhancing effect decreased again. NO caused a rapid and transient increase in intracellular guanosine-3',5'-cyclic monophosphate (cGMP) levels. The enhancing effect of NO on random migration was largely reversed by the inhibitors of cGMP accumulation, LY-83583 and methylene blue, and by the antagonists of cGMP-dependent protein kinase, 8-bromoguanosine-3',5'-cyclic monophosphorothioate, Rp-isomer (Rp-8-Br-cGMPS) and 8-(4-chlorophenylthio)-guanosine-3',5'-cyclic monophosphorothioate (Rp-8-pCPT-cGMPS). These observations strongly suggest that the enhancement of random migration by NO is mediated by cGMP and cGMP-dependent protein kinase. The effect of NO on migration did not occur in the absence of extracellular calcium. Although NO did not induce a measurable elevation of intracellular free calcium, pre-incubation with the intracellular calcium chelator Fura-2/AM abolished the enhancing effect of NO. It appears therefore that a small change in the level of cytoplasmic free calcium does play a role in the enhancement of random migration by NO. High concentrations of NO were found to inhibit chemotaxis induced by an optimal concentration of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP). This inhibitory effect was also dependent on the presence of extracellular calcium. A role for cGMP in the inhibition of fMLP-induced chemotaxis by NO is not supported by our measurements of intracellular cGMP levels. In contrast to the effects on fMLP, NO did not affect chemotaxis induced by the phorbol ester PMA. In conclusion, we show that NO, not derived from NO donors but applied directly, may stimulate or inhibit neutrophil migration, dependent on the concentration. The enhancing effect of NO on random migration is mediated by cGMP, which emphasizes the importance of this second messenger as a modulator of neutrophil functional.

Aminoquinolines↗

PubMed1996

The effect of endothelin-2 (ET-2) on migration and changes in cytosolic free calcium of neutrophils.

The effect of endothelin-2 (ET-2) on neutrophil migration and intracellular calcium was studied. Depending on the concentration, ET-2 enhanced or inhibited neutrophil migration. At low concentrations ET-2 caused a chemotactic stimulation of migration, in contrast with endothelin-1 (ET-1) which caused a chemokinetic stimulation of migration. At higher concentrations ET-2 inhibited formyl-methionyl-leucyl-phenylalanine (fMLP)-activated migration. Both activation and inhibition by ET-2 were completely dependent on extracellular Ca2+. Unlike ET-1 which caused an increase in cytosolic free Ca2+ at a concentration which stimulated migration, ET-2 caused a measurable increase of cytosolic free Ca2+ at a concentration which did not stimulate migration. This strongly suggests that there is no correlation between maximal stimulation of cytoplasmic free calcium, and maximal stimulation of migration. Influx of extracellular Ca2+ was required for both activation of migration and change in cytosolic free Ca2+, because no effect was observed in the absence of extracellular Ca2+, and because blockers of Ca(2+)-influx inhibited ET-2-activated migration. The ETA-receptor antagonist cyclo-(-D-Trp-D-Asp-Pro-D-Val-Leu) (BQ123), and the ETB-receptor antagonist [Cys11-Cys15]-endothelin-1(11-21) (IRL1038) antagonized the stimulatory effect of ET-2 on migration, and the inhibitory effect of high concentrations of ET-2 on fMLP-activated chemotaxis. This suggests that both the ETA-receptor and the ETB-receptor are involved in the stimulatory effect of low concentrations of ET-2, and in the inhibitory effect of high concentrations of ET-2.

Animals↗

PubMed1996

The role of cyclic nucleotides in neutrophil migration.

1. The literature concerning the effects of cAMP and especially cGMP on neutrophil migration is reviewed. 2. Experiments with agents that enhance cGMP level, and with electroporated neutrophils in which cGMP was introduced, show that the nucleotide has different effects. There is a maximal stimulation at a specific concentration while higher concentrations are less effective or even inhibitory. 3. Some physiologically active peptides such as granulocyte-macrophage colony-stimulating factor (GM-CSF), atrial natriuretic factor, and endothelin appear to modify neutrophil migration via a cGMP-dependent mechanism. 4. Dependent on concentration and conditions (random migration vs. fMLP-activated migration, using nitric oxide (NO), NO donors, and inhibitors of NO synthase), NO has stimulatory or inhibitory effects on neutrophil migration. 5. The differential effects of cGMP and cAMP on neutrophil migration are discussed with regard to intracellular actions, metabolism, interaction with calcium, and relation to structural changes required for cell movement.

Animals↗

PubMed1995

Ryanodine as inhibitor of chemotactic peptide-induced chemotaxis in human neutrophils.

Ryanodine gave a moderate inhibition of chemotactic peptide-activated chemotaxis by intact human neutrophils. Chemotaxis by electroporated neutrophils was strongly inhibited in the nanomolar concentration range. Inhibition of chemotaxis by electroporated neutrophils occurs at concentrations known to open calcium channels in ryanodine-sensitive Ca2+ stores. Whereas migration by formyl-methionyl-leucyl-phenylalanine (fMLP)- or interleukin-8-activated electroporated neutrophils was strongly inhibited by ryanodine, chemotaxis induced by protein kinase C activators was not affected. This suggests that the importance of ryanodine-sensitive Ca2+ stores for migration depends on the type of activator used. Ryanodine gave an increase of cytoplasmic free calcium due to the liberation of calcium from internal stores and to the influx of extracellular calcium. The results show that the neutrophil contains ryanodine-sensitive calcium stores that might be involved in receptor-mediated chemotaxis.

Caffeine↗

PubMed1995

The role of calcium ions in DEAE-dextran-induced stimulation of neutrophil migration.

The polycation DEAE-dextran caused a strong enhancement of non-directed migration of rabbit peritoneal neutrophils. The activating effect on migration was completely annulled in the presence of the polyanion poly-D-glutamic acid, indicating that the effect depended on the positive charge of the macromolecule. Chemotaxis activated by the chemotactic peptide fMLP was only slightly affected by the polycation. In contrast with fMLP-activation, stimulation of migration by DEAE-dextran was dependent on the presence of extracellular Ca2+. DEAE-dextran also stimulated migration of electroporated neutrophils. The stimulation was absent when calcium was not present; the increase of migration was strongest at Ca(2+)-concentrations between 100 nM and 1 microM Ca2+. This indicates that the requirement for extracellular Ca2+ in intact cells is a reflection of the intracellular requirement. Several types of calcium blockers gave a moderate inhibition of DEAE-dextran activated migration. Activation of migration by DEAE-dextran of electroporated neutrophils was completely inhibited by calcium channel blockers, at very low concentrations. The results suggest that both Ca(2+)-fluxes across the plasma membrane and Ca2+ from intracellular stores are required for DEAE-activated migration, and that the calcium from the intracellular source is required on a place where the extracellular Ca2+ has no, or limited, admittance.

Animals↗

PubMed1995

Atrial natriuretic factor stimulates migration by human neutrophils.

Atrial natriuretic factor causes a strong stimulation of human neutrophil migration in the concentration range of 4 x 10(-9) and 10(-7) M. The effect, which depends on the presence of extracellular Mg2+ but not on extracellular Ca2+, is composed of a chemokinetic and a chemotactic component. Cyclic GMP level of neutrophils is enhanced by atrial natriuretic factor. Two inhibitors of soluble guanylate cyclase, 6-anilino-5,8-quinolinedione (LY 83583) and methylene blue, have no effect on stimulation of migration by atrial natriuretic factor. Atrial natriuretic factor-activated migration is inhibited by pertussis toxin. Migration by electroporated neutrophils is synergistically enhanced by guanosine-5'-[gamma thio]triphosphate (GTP gamma[S]) and atrial natriuretic factor or by GTP gamma[S] and chemotactic peptide, while GTP gamma[S] and dioctanoyl glycerol give an additive effect. The results suggest that besides a modulation via cGMP a part of the effect of atrial natriuretic factor on migration is regulated via the ANF receptor-subtype that does not activate guanylate cyclase.

Aminoquinolines↗

PubMed1995

Stimulation and inhibition of neutrophil chemotaxis by endothelin-3.

Depending on the concentration, endothelin-3 (ET-3) has activating or inhibitory effects on neutrophil migration. At concentrations below 10 nM, neutrophil migration was stimulated by ET-3. The stimulating effect of ET-3 was mainly chemotactic, in contrast with that of ET-1, which was mainly chemokinetic. Concentrations of ET-3 lower than 10 nM potentiated chemotaxis activated by fMet-Leu-Phe (fMLP), whereas concentrations higher than 10 nM inhibited fMLP-activated neutrophil chemotaxis. The ETA receptor antagonist BQ123, the ET receptor agonist sarafotoxin S6c, and the ETB receptor antagonist IRL 1038 inhibited ET-3- and fMLP-activated migration. All of these compounds reversed the inhibitory effect of high concentrations of ET-3 on fMLP-activated chemotaxis. The results suggest that the ETA and the ETB receptor are both involved in the activating and inhibitory effects of ET-3.

Animals↗

PubMed1994

Endothelin-induced activation of neutrophil migration.

Migration of rabbit peritoneal neutrophils was stimulated by endothelin-1 (ET-1) up to 2.10(-8) M. Higher concentrations inhibited random migration. The stimulating effect of ET-1 was inhibited by BQ-123, a specific antagonist of the ETA receptor. A checkerboard assay showed that the stimulating effect of ET-1 on neutrophil migration was chemokinetic rather than chemotactic. Extracellular Ca2+ was required for the activating effect of ET-1. Non-selective calcium channel blockers such as econazole and La3+ strongly inhibited ET-1-activated migration but had little effect on fMLP-activated migration, underlining the importance of Ca2+ influx for ET-1-activated migration. Studies with electroporated neutrophils showed that the increase in migration was most pronounced at calcium concentrations between 100 nM and 1 microM. ET-1-activated migration of electroporated cells was completely blocked by low concentrations of calcium-channel blockers such as verapamil and nitrendipine. Migration by intact cells was inhibited by the same concentration of verapamil, but to a lesser degree; nitrendipine had little effect on migration of intact cells. This suggests that calcium derived from intracellular stores is required for migration activated by ET-1. Protein kinase C, protein tyrosine kinase, and phosphatase activity were involved in the activating effect of ET-1 on neutrophil migration. ET-1 did not induce exocytotic enzyme release, in neither the presence nor the absence of cytochalasin B.

Animals↗

PubMed1994

Characterization of exocytosis in electropermeabilized neutrophils by flow cytometric analysis: difference in sensitivity to calcium and guanosine-5'-[gamma-thio]triphosphate.

When rabbit neutrophils were subjected to two electrical discharges of 4.75 kV/cm, the cells became permeable to propidium iodide. Measurement of propidium iodide fluorescence using flow cytometry showed that all cells in the suspension were permeabilized. The cells remained permeable for > 20 min when the cells were stored at 0 degree C. When exocytosis was induced by Ca2+ alone, the orthogonal light scatter (a sensitive parameter for cell granularity) of the complete population changed depending on the concentration. All the cells were equally sensitive to Ca2+ and showed a similar degree of exocytosis at the same time. In the presence of a fixed concentration of Ca2+ and a variable concentration of guanosine-5'-[v-thio]triphosphate (GTP gamma S), a division of the cell population was observed in the orthogonal light scatter histogram. At low GTP gamma S concentrations, a part of the population showed complete exocytosis and a part of the population showed almost no exocytosis. With increasing GTP gamma S concentrations, the light scatter pattern of the population changed indicating that the cells were gradually sensitive to GTP gamma S. Electropermeabilized neutrophils showed an equal sensitivity to Ca2+ and a graded sensitivity to GTP gamma S. Flow cytometry is considered as an ideal tool to study such an effect on a cell-to-cell basis.

Animals↗

PubMed1994

Exocytosis in neutrophils induced by thapsigargin and other inhibitors of calcium ATP-ase.

Inhibitors of the Ca(2+)-ATPase of intracellular calcium stores, such as thapsigargin, cyclopiazonic acid and 2,5-di-(t-butyl)-1,4-benzohydro-quinone, causes exocytosis in rabbit peritoneal neutrophils. In the absence of extracellular Ca2+ no exocytosis takes place. Fluoride, a non-specific inhibitor of Ca(2+)-ATPase, also causes exocytosis. It is known that all agents tested cause both a release of calcium from intracellular stores as well as an influx of extracellular calcium. The results indicate that induction of exocytosis is not due to a release of calcium from intracellular stores, but to the influx of extracellular calcium. Thapsigargin-induced exocytosis is not inhibited by L-type channel antagonists like verapamil, but is strongly inhibited by lanthanum ions, suggesting that the calcium required for induction of exocytosis is not entering via L-type channels, but via La(3+)-sensitive calcium channels.

Animals↗

PubMed1993

Neutrophil chemotaxis induced by the diacylglycerol kinase inhibitor R59022.

The diacylglycerol kinase inhibitor R59022 induced chemotaxis in neutrophils. The response to R59022 was primarily chemotactic and only very little chemokinetic. Pretreatment with the protein kinase C inhibitors staurosporine and AMG-C16 inhibited chemotaxis induced by R59022 indicating the involvement of protein kinase C. In contrast, chemotaxis induced by fMet-Leu-Phe was only slightly inhibited by staurosporine and AMG16. The effects of R59022 were comparable to the effects of the protein kinase C activators DiC8 and PMA and suggest an involvement of protein kinase C. Pretreatment with pertussis toxin inhibited R59022-induced migration, fMet-Leu-Phe-induced migration, and random migration. GTP gamma S, which stimulates migration of electropermeabilized neutrophils by itself, causes an additive increase of migration in electropermeabilized neutrophils stimulated with a suboptimal concentration R59022, but causes a synergistic increase of migration in cells stimulated with a suboptimal concentration fMet-Leu-Phe. The effects of GTP gamma S on migration are completely inhibited by AMG-C16. This suggests that the GTP-binding protein involved in R59022-activated migration is the G protein that is associated with random migration.

Animals↗

PubMed1993

The effect of cyclic GMP and cyclic AMP on migration by electroporated human neutrophils.

Human neutrophils retain the ability to migrate when they are electroporated; this enables the study of potential mediators by direct application to the cell interior. Cyclic GMP strongly enhances random migration by electroporated human neutrophils. The effect is maximal at a concentration of 10 microM. The potentiating effect of cGMP is chemokinetic. Chemotaxis of electroporated neutrophils activated by formylmethionylleucylphenylalanine (fMLP) is stimulated by cGMP at concentrations up to 10 microM; higher concentrations inhibit chemotaxis. Cyclic AMP resembles cGMP in that both activation and inhibition may occur. However, activation occurs over a very small concentration range, and inhibition is a predominant feature. Cyclic nucleotide-activated migration is dependent on Ca2+, in contrast with activation of migration by fMLP.

Calcium↗

PubMed1993

Strontium and barium induce exocytosis in electropermeabilized neutrophils.

Calcium, strontium and barium induced an exocytotic response in electropermeabilized rabbit neutrophils while magnesium was without any effect. The extent of enzyme release was found to depend upon the concentration of these cations. For all cations, an optimum concentration was found with the same maximum enzyme release. At concentrations higher than optimum a decrease in lysozyme release was observed. Efficiency to induce enzyme release was in the order: Ca2+ > Sr2+ > Ba2+. Enzyme release was significantly enhanced by guanosine-5'-[gamma-thio]triphosphate (GTP gamma S) resulting in a shift to the left of the dose/response curve. The enhancement by GTP gamma S was strongest with Ca2+, was less with Sr2+, and was very little with Ba2+. The time course of lysozyme release was the same for Ca2+, Sr2+, and Ba2+ in the presence and absence of GTP gamma S when suboptimal cation concentrations were used. A decrease in responsiveness to the effectors after electropermeabilization was observed with Ca2+, Sr2+ and Ba2+ in the presence and absence of GTP gamma S. The lysozyme release induced by the different cations was not inhibited by the protein kinase C inhibitor staurosporine and was slightly affected by pertussis toxin. Ca2+ and Sr2+, but not Ba2+, potentiated formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) induced enzyme release in intact neutrophils. The divalent cation ionophore A23187 induced enzyme release in the presence of Ca2+ and Sr2+ but not in the presence of Ba2+. The results obtained with electropermeabilized neutrophils indicate that Sr2+ and Ba2+ can act as substitutes for Ca2+ in activating exocytosis, and that permeabilized neutrophils provide the best tool to investigate the effects of alkaline earth ions in exocytosis.

Animals↗

PubMed1993

Modulation of neutrophil migration by captopril.

Because neutrophils might be involved in some of the therapeutic effects of captopril we studied the effect of captopril on neutrophil migration. Captopril strongly enhances migration by rabbit peritoneal neutrophils. Stimulation by captopril was maximal at a concentration of about 400 microM; at higher concentrations stimulation decreased again. The stimulatory effect is partly chemokinetic, and partly chemotactic. Captopril disulfide also stimulates migration, though the stimulating effect is less than that of captopril. Captopril-induced stimulation of migration was strongly inhibited by pretreatment of neutrophils with pertussis toxin, indicating that the stimulation is mediated by a pertussis toxin-sensitive G protein. Intact sulfhydryl groups on the cell surface are required for stimulation because inactivation of these groups with the non-penetrating sulfhydryl reagent 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) completely abolishes the stimulating effect of captopril and of captopril disulfide. Both captopril and captopril disulfide cause an enhancement of cyclic GMP level in the neutrophil. The enhancement of both the cGMP level and that of migration is blocked by methylene blue and by LY-83583, suggesting that the stimulating effect of captopril is mediated by cGMP. Inhibitors of NO generation, such as NG-monomethyl-L-arginine, NG-nitro-L-arginine and canavanine have no effect on captopril-induced stimulation of migration, indicating that NO is not involved in the stimulating effect of captopril.

Animals↗