Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04141 (granulocyte-macrophage colony-stimulating factor)
 6,790 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pretreatment of human polymorphonuclear leukocytes with the recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) enhances leukotriene biosynthesis in response to a receptor agonist (e.g. N-formyl-methionyl-leucyl-phenylalanine, fMLP) or a Ca(2+)-ionophore (e.g. ionomycin). This priming effect could be traced back to an elevated release of arachidonic acid from the phospholipid pools and hence an increased leukotriene biosynthesis by 5-lipoxygenase. Preincubation of polymorphonuclear leukocytes with GM-CSF did not influence the basal intracellular Ca2+ level and does not enhance cytosolic free calcium after stimulation with fMLP or ionomycin. Only a small increase in the second Ca2+ phase after receptor agonist stimulation was found. However, the Ca(2+)-threshold level necessary for the liberation of arachidonic acid by phospholipase A2 was decreased from 350-400 nM calcium in untreated cells to about 250 nM calcium in primed cells. This allows phospholipase A2 to be activated by a release of calcium from intracellular stores and by ionomycin concentrations which are ineffective in untreated cells. Protein biosynthesis inhibitors like actinomycin D (10 micrograms/ml) and cycloheximide (50 micrograms/ml) had no effect on the enhanced leukotriene biosynthesis in primed cells after stimulation with ionomycin. However, staurosporine (200 nM), an inhibitor of protein kinase C totally abolished the priming effect of GM-CSF after stimulation with ionomycin. The priming effect of GM-CSF could be mimicked by phorbol myristate acetate (PMA; 1 nM) and no additive or synergistic effect was found on leukotriene biosynthesis by simultaneous pretreatment with PMA and GM-CSF and stimulation with either fMLP or ionomycin. These results provide evidence that the enhanced arachidonic acid release in GM-CSF-primed polymorphonuclear leukocytes after stimulation with either fMLP or ionomycin involves activation of protein kinase C which, by a still unknown mechanism, reduces the Ca2+ requirement of phospholipase A2.
 ...
PMID:Priming of human polymorphonuclear leukocytes with granulocyte-macrophage colony-stimulating factor involves protein kinase C rather than enhanced calcium mobilisation. 154 Dec 84

Protein antigens with both allergenic and immunoprotective properties represent appropriate molecules to study IgE and IgG regulation. We have established a panel of T cell clones specific to bee venom phospholipase A2 (PLA) from human individuals allergic, hyposensitized or immune (protected) to bee sting. All clones obtained were CD3+, CD4+ and expressed alpha, beta T cell receptor. Depending on the T cell clone, maximal stimulation required 1 to 100 micrograms/ml of PLA, and the addition of interleukin (IL)-2 and/or IL-4 increased their antigen-dependent proliferation. Following antigen stimulation, the clones produced IL-4, interferon-gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor. Most clones also produced tumor necrosis factor alpha (TNF-alpha) and tumor necrosis factor beta (TNF-beta), and some produced IL-5 and/or IL-2. Both absolute and relative amounts of secreted cytokines depended on the antigen concentration. At low antigen doses, IL-4 was produced but little or not IFN-gamma, whereas at higher PLA concentrations significant amounts of both IL-4 and IFN-gamma were obtained. Thus, these PLA-specific T cell clones could be classified according to the changes in the ratio of IL-4/IFN-gamma production in response to increasing antigen concentrations. Clones derived from allergic and hyposensitized individuals required higher critical amounts of antigen for IFN-gamma induction, and expressed increasing IL-4/IFN-gamma ratios with increasing concentrations of PLA. Modulation of cytokine patterns by the dose of the antigen may be a driving force for IgE or IgG formation resulting in allergy or immunoprotection.
 ...
PMID:Bee venom phospholipase A2-specific T cell clones from human allergic and non-allergic individuals: cytokine patterns change in response to the antigen concentration. 160 Oct 30

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic cytokine which produces diverse biological effects in target cells of myeloid origin. GM-CSF enhances the production of superoxide anion (O2-) by mature neutrophils in response to chemotactic peptides such as formyl-methionyl-leucyl-phenylalanine (fMLP), but alone it has no effect on this system. This process has been termed "priming." fMLP activates neutrophils via a pertussis toxin-sensitive GTP-binding protein, leading to the rapid production of the second messengers diacylglycerol (DAG) and inositol trisphosphate, via phosphatidylinositol turnover, and arachidonic acid (AA) by a presumptive phospholipase A2-mediated mechanism. All three second messengers may lead to the generation of O2-. We investigated the effect of priming of GM-CSF on these systems. GM-CSF had no effect on fMLP-stimulated DAG and inositol trisphosphate levels, nor did it amplify the response to exogenously added phorbol ester (to mimic the action of DAG) or calcium ionophore. Neutrophils primed with the cytokine showed a small, but significant, enhancement of fMLP-stimulated AA release. Compared with unprimed controls, primed neutrophils also showed a significant increase in O2- production when stimulated with either AA or the nonhydrolyzable GTP analogue, GTP-gamma-S. The magnitude of enhanced O2- production was similar to that observed after fMLP treatment of primed cells. All of these effects, including the increased sensitivity to AA treatment, were inhibited by pertussis toxin. These data show that GM-CSF primes neutrophils by modulating the activity of at least one pertussis toxin-sensitive G protein coupled to a metabolic pathway that mobilizes and utilizes arachidonic acid.
 ...
PMID:Granulocyte-macrophage colony-stimulating factor primes neutrophils by activating a pertussis toxin-sensitive G protein not associated with phosphatidylinositol turnover. 254 84

We have previously shown that granulocyte-macrophage colony-stimulating factor (GM-CSF) gene expression induced by interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) in the murine stromal cell line +/+.1-LDA 11 involves activation of phospholipase A2 (PLA2). Furthermore, induction of GM-CSF gene expression due to release of arachidonic acid as a result of PLA2 activation was mediated by the transcriptional factor c-jun. In the present study, we have investigated the potential mechanism involved in the induction of c-jun gene expression by arachidonic acid. Arachidonic acid induced transcription of c-jun mRNA. Downregulation of protein kinase C (PKC) by chronic exposure of stromal cells to the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA; 400 nmol/L) did not effect c-jun expression induced by arachidonate. Moreover, pretreatment of cells with the PKC inhibitor, calphostin C (1 mumol/L), caused a marked decrease of c-jun expression induced by TPA, but had no influence on c-jun expression induced by arachidonate. To explore the hypothesis that a tyrosine kinase signalling pathway, independent of PKC activation, was involved in arachidonate-induced c-jun expression, stromal cells were pretreated with the protein tyrosine kinase inhibitor, genistein, before challenge with arachidonic acid. Arachidonate 50 mumol/L)-induced c-jun expression was inhibited, in a dose- and time-dependent manner, by genistein. Genistein similarly inhibited c-jun expression in stromal cells exposed to IL-1 (500 U/mL) plus TNF-alpha (500 U/mL). The potential role of a tyrosine kinase pathway in arachidonate-mediated c-jun expression was further investigated by assaying the tyrosine kinase activity of cells challenged with arachidonic acid, IL-1, and TNF-alpha. Exposure of stromal cells to arachidonic acid induced a 2.1-fold increase in intracellular tyrosine kinase activity determined by phosphorylation of the synthetic peptide, raytide, in the presence of [gamma-32P]-ATP. Similarly, IL-1 and TNF-alpha induced 1.7- and 2.4-fold increases in tyrosine protein kinase activity, respectively. The effect of arachidonic acid on tyrosine kinase activity was inhibited by genistein and was enhanced by sodium vanadate. The increase of protein tyrosine kinase activity detected in arachidonate-stimulated cells was associated, in a dose- and time-dependent fashion, with tyrosine phosphorylation of 240-, 40-, and 29-kD substrates. These results are consistent with the hypothesis that a tyrosine phosphorylation process is triggered by arachidonate as an early event in the signalling pathway that leads to increased expression of c-jun.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Arachidonic acid induces c-jun gene expression in stromal cells stimulated by interleukin-1 and tumor necrosis factor-alpha: evidence for a tyrosine-kinase-dependent process. 757 89

1. Platelet-activating factor (PAF) and leukotriene B4 (LTB4), two potent lipid mediators synthesized by activated neutrophils, are known to stimulate several neutrophil functional responses. In this study, we have determined that endogenous LTB4 and PAF exert autocrine effects on LT synthesis, as well as the underlying mechanism involved. 2. Pretreatment of neutrophils with either pertussis toxin (PT), or with receptor antagonists for LTB4 and PAF, resulted in an inhibition of LT synthesis induced by calcium ionophore, A23187. This inhibition was most marked at submaximal (100-300 nM) A23187 concentrations, whilst it was least at ionophore concentrations which induce maximal LT synthesis (1-3 microM). Thus newly-synthesized PAF and LTB4 can enhance LT synthesis induced by A23187 under conditions where the LT-generating system is not fully activated. 3. In recombinant human (rh) granulocyte-macrophage colony-stimulating factor (GM-CSF)-primed neutrophils, LT synthesis in response to chemoattractants (fMet-Leu-Phe or rhC5a) was also significantly inhibited by the LTB4 receptor antagonist, and to a lesser extent by PAF receptor antagonists. 4. Further investigation revealed that LTB4 and/or PAF exert their effects on LT synthesis via an effect on arachidonic acid (AA) availability, as opposed to 5-lipoxygenase (5-LO) activation. Indeed, the receptor antagonists, as well as PT, inhibited LT synthesis and AA release to a similar extent, whereas 5-LO activation (assessed with an exogenous 5-LO substrate) was virtually unaffected under the same conditions. Accordingly, we showed that addition of exogenous LTB4 could enhance AA availability in response to chemoattractant challenge in rhGM-CSF-primed cells, without significantly affecting the 5-LO activation status. Our data show that newly-generated PAF and LTB4 have the ability to positively feedback on LT synthesis by acting at the level of the phospholipase A2/re-esterification component of the LT biosynthetic pathway in neutrophils. Such autocrine affects are likely to represent an important amplification step of LT synthesis, and may as such contribute to the rapid onset, as well as to the evolution, of inflammatory responses.
 ...
PMID:Autocrine enhancement of leukotriene synthesis by endogenous leukotriene B4 and platelet-activating factor in human neutrophils. 801 62

Murine peritoneal exudate macrophages (PEM) co-express granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage CSF (M-CSF) receptors, among others. Treatment of PEM with lipopolysaccharide (LPS) or tumor-promoting phorbol ester (12-O-tetradecanoylphorbol-13-acetate [TPA]) induces a rapid but transient loss of M-CSF receptors in PEM. GM-CSF receptors are not affected by this treatment. The loss of M-CSF receptors induced by LPS can be inhibited by neomycin and compound 48/80, two potent phospholipase C (PLC) inhibitors, but not by phospholipase A2, calpain, protein kinase C (PKC) or protease inhibitors. On the other hand, the loss of M-CSF receptors induced by TPA has been prevented by PKC inhibitors but not by PLC inhibitors. PLC inhibitors also prevent LPS-suppressed receptor-mediated internalization of radiolabeled recombinant human (rh) M-CSF by macrophages. Similar prevention of LPS-induced M-CSF receptor downregulation was observed in human monocytes that had been pretreated with PLC inhibitors. Our results show that 1) TPA-induced M-CSF receptor loss is strictly dependent on PKC activation; 2) PLC activation alone also leads to downregulation of M-CSF receptors; and 3) LPS-induced M-CSF receptor downregulation in PEM is mediated primarily through a PLC-dependent pathway. Our data also imply that the expression of M-CSF but not GM-CSF receptors is linked to an important, yet unknown, PLC-sensitive component(s) whose hydrolysis may lead to downregulation of M-CSF receptors.
 ...
PMID:Downregulation of M-CSF receptors by lipopolysaccharide in murine peritoneal exudate macrophages is mediated through a phospholipase C dependent pathway. 851 62

Intermittent painful crises due to vasoocclusion are the major clinical manifestation of sickle cell disease (SCD), but subclinical episodes may also occur. There is sparse evidence for the involvement of neutrophils in the pathophysiology of SCD, but production of cytokines by the damaged endothelium might influence neutrophil function and modulate responses to subsequent cytokine exposure. In addition, the activation of neutrophils in the microcirculation could itself exacerbate vasoocclusion. To test whether neutrophil inflammatory responses were altered in SCD, neutrophil phospholipase A2 and NADPH oxidase activity in response to in vitro priming by granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF-alpha) were measured both during and between painful crises. Resting levels of neutrophil phospholipase A2 activity in steady-state SCD (4.0% +/- 0. 5% of total cell radioactivity) were raised relative to control values (2.0% +/- 0.2%, n = 10, P = .008). There was no defect of agonist-stimulated phospholipase A2 or NADPH oxidase activity in steady-state SCD; however, the ability of phospholipase A2 to respond to priming with GM-CSF was attenuated to 63% +/- 17% of control values (n = 10, P = .04). Similarly, neutrophil NADPH oxidase activity after priming with GM-CSF and TNF-alpha was, respectively, 65% +/- 11% (n = 7, P = .03) and 57% +/- 7% of control (n = 10, P = .007) in steady-state disease, and was further reduced during painful vasoocclusive crises to 34% +/- 9% and 25% +/- 3% of control for GM-CSF and TNF-alpha, respectively. These data were not explained by poor splenic function or any racial factor, as normal cytokine responses were seen in splenectomized patients in remission from Hodgkin's disease and in healthy Afro-Caribbean subjects. Abnormal neutrophil cytokine priming responses were not observed in either patients with rheumatoid arthritis or iron-deficiency anemia. Our findings are indicative of an ongoing inflammatory state in SCD between painful crises involving neutrophil activation and an abnormality of cytokine-regulated neutrophil function, which may compromise the host defenses against certain microorganisms.
 ...
PMID:Raised neutrophil phospholipase A2 activity and defective priming of NADPH oxidase and phospholipase A2 in sickle cell disease. 955 1

We have examined whether certain secreted factor(s) is involved in oxidized low density lipoprotein (Ox-LDL)-induced murine macrophage growth. An antibody against granulocyte-macrophage colony-stimulating factor (GM-CSF) effectively inhibited Ox-LDL-induced macrophage growth by >80%. Ox-LDL as well as phospholipase A2-treated acetylated LDL enhanced mRNA levels and protein release of GM-CSF from macrophages, while neither acetylated LDL nor lysophosphatidylcholine (lyso-PC) showed such effects. The maximal induction of GM-CSF by Ox-LDL was noted at 4 h, followed by a time-dependent decrease to a basal level within 24 h. Ox-LDL-induced macrophage growth was inhibited by 75% by replacement of the culture medium at 24 h by a fresh medium containing the same concentration of Ox-LDL, when GM-CSF had already returned to the basal level. Thus, a cytokine(s) other than GM-CSF is also expected to participate in Ox-LDL-induced macrophage growth in a later phase. The Ox-LDL-induced GM-CSF release was inhibited by calphostin C, a protein kinase C inhibitor, and was significantly reduced in macrophages from the knockout mice lacking class A, type I and type II macrophage scavenger receptors (MSR-AI/AII). These results taken together indicate that effective endocytosis of lyso-PC of Ox-LDL by macrophages through MSR-AI/AII and subsequent protein kinase C activation have led to GM-CSF release into the medium which may play a priming role in conjunction with other cytokines in Ox-LDL-induced macrophage growth.
 ...
PMID:Induction of murine macrophage growth by oxidized low density lipoprotein is mediated by granulocyte macrophage colony-stimulating factor. 977 54

The activation of phospholipase A(2) (PLA(2)) with release of eicosanoids and prostanoids in mature myeloid cells and the augmentation (priming) of this activity by cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) are central to the inflammatory process. Yet, there are few data concerning PLA(2) activity and its regulation by growth factors in primary hematopoietic cells. We therefore analyzed the PLA(2) activity of mobilized human CD34 antigen-positive (CD34(+)) stem cells by quantitation of the extracellular release of (3)H-arachidonate. The PLA(2) activity of CD34(+) cells stimulated with calcium ionophore (A23187) was of similar magnitude to that of mature neutrophils and monocytes. Preincubation of CD34(+) cells with stem cell factor (SCF) before A23187-stimulation resulted in primed PLA(2) activity, whereas interleukin-3 (IL-3), GM-CSF, and tumor necrosis factor alpha had no significant effect. When CD34(+) cells were induced to differentiate, PLA(2) activity remained responsive to SCF for several days, but after 8 days, at which stage morphological and functional evidence of maturation was occurring, priming of PLA(2) by SCF could no longer be elicited, whereas responses to GM-CSF and IL-3 had developed. The further metabolism of arachidonic acid to eicosanoids by CD34(+) cells was not detected by either thin-layer chromatography, enzyme immunoassay, or differential spectroscopy. SCF stimulated the rapid but transient activation of ERK2 (p42 MAP kinase) in CD34(+) cells, and we used the MAP kinase kinase inhibitor, PD 098059, which at 30 micromol/L blocks ERK2 activation in CD34(+) cells, to investigate whether SCF-mediated priming of arachidonate release was mediated by this kinase. PD 098059 only partially inhibited A23187-stimulated PLA(2) activity primed by SCF, suggesting the involvement of ERK2 and possibly a further signal transduction pathway. Methyl arachidonyl fluorophosphonate (5 micromol/L), a dual inhibitor of i and cPLA(2) isoforms, completely inhibited arachidonate release without affecting ERK2 activation, demonstrating the lack of cellular toxicity. These data provide the first evidence that primitive myeloid cells have the capacity to release arachidonate, which is regulated by an early acting hematopoietic growth factor important for the growth and survival of these cells.
 ...
PMID:Primitive myeloid cells express high levels of phospholipase A(2) activity in the absence of leukotriene release: selective regulation by stem cell factor involving the MAP kinase pathway. 1043 14

Leukotrienes (LT) are mediators derived from the 5-lipoxygenase (5-LO) pathway, which play a role in host defense, and are synthesized by both monocytes (peripheral blood monocyte [PBM]) and neutrophils (PMN). Because 5-LO metabolism is reduced in alveolar macrophages and PMN from acquired immunodeficiency syndrome (AIDS) subjects, we investigated the synthesis of LT by PBM and PMN from these subjects. There was a reduction (74.2% +/- 8.8% of control) in LT synthesis in PBM from human immunodeficiency virus (HIV)-infected compared with normal subjects. Expression of 5-LO (51.2% +/- 8.8% of control), and 5-LO activating protein (FLAP) (48.5% +/- 8.0% of control) was reduced in parallel. We hypothesized that this reduction in LT synthetic capacity in PBM and PMN was due to reduced cytokine production by CD4 T cells, such as granulocyte-macrophage colony-stimulating factor (GM-CSF). We treated 10 AIDS subjects with GM-CSF for 5 days. PBM 5-LO metabolism ex vivo was selectively increased after GM-CSF therapy and was associated with increased 5-LO and FLAP expression. PMN leukotriene B(4) (LTB(4)) synthesis was also augmented and associated with increased 5-LO, FLAP, and cytosolic phospholipase A(2) expression. In conclusion, as previously demonstrated for PMN, PBM from AIDS subjects also demonstrate reduced 5-LO metabolism. GM-CSF therapy reversed this defect in both PBM and PMN. In view of the role of LT in antimicrobial function, cytokine administration in AIDS may play a role as adjunct therapy for infections.
 ...
PMID:Granulocyte-macrophage colony-stimulating factor upregulates reduced 5-lipoxygenase metabolism in peripheral blood monocytes and neutrophils in acquired immunodeficiency syndrome. 1057 6


1 2 Next >>