Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10145 (IL-8)
 23,849 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stimulated human monocytes release several proteins thought to play a role in inflammation, including interleukin 1, tumor necrosis factor, and plasminogen activator. We have purified another proinflammatory protein that is chemotactic for human neutrophils from conditioned medium of lipopolysaccharide-stimulated monocytes. After a series of steps that included anion-exchange chromatography, gel filtration, and HPLC on cation-exchange and reverse-phase columns, an apparently pure protein was obtained that migrated as a single 7-kDa band on NaDodSO4/polyacrylamide gels under reducing or nonreducing conditions. The amino acid composition of this monocyte-derived neutrophil chemotactic factor was different from that of interleukin 1 and tumor necrosis factor. N-terminal amino acid sequence of the first 42 residues was determined. This portion of the molecule has up to 56% sequence similarity with several proteins that may be involved in host responses to infection or tissue injury. It is identical to a portion of a sequence deduced from an mRNA induced by staphylococcal enterotoxin treatment of human leukocytes. At the optimal concentration of 10 nM, 50% of neutrophils added to chemotaxis assay wells migrated toward the pure attractant. Potency and efficacy are comparable to that of fMet-Leu-Phe, which is often used as a reference. In contrast to many attractants, the protein was not chemotactic for human monocytes.
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PMID:Purification of a human monocyte-derived neutrophil chemotactic factor that has peptide sequence similarity to other host defense cytokines. 348 May 40

Stimulation of heparinized blood with 1 microM formyl-methionyl-leucyl-phenylalanine (FMLP) resulted in the formation of < 30 pmol/ml plasma of 5-lipoxygenase (5-LO) products. The preincubation of blood with 1 microgram/ml of lipopolysaccharide (LPS) (Escherichia coli 0111-B4) for 30 min before stimulation with FMLP resulted in the accumulation of 250-300 pmol of 5-LO products per ml plasma. The major products detected were leukotriene B4 and (5S)-hydroxy-6,8,11,14-eicosatetraenoic acid which were produced in equivalent amounts. The priming activity was detectable with as little as 1-10 ng LPS per ml blood and was optimal using 1-10 micrograms LPS/ml blood. The priming for 5-LO product synthesis was optimal after 20-30 min of preincubation with LPS and declined at preincubation times > 30 min. The priming effect of LPS was also observed using the complement fragment C5a or interleukin 8 as agonists. Polymorphonuclear leukocytes (PMN) and peripheral blood mononuclear cells accounted for 80 and 20% of the synthesis of 5-LO products, respectively. The ability of LPS to prime isolated PMN was dependent on the presence of plasma and was inhibited by the anti-CD14 antibody IOM2, indicating a CD14-dependent priming mechanism. The priming of whole blood with tumor necrosis factor alpha (TNF-alpha) and LPS was additive and the presence of mononuclear cells did not enhance the ability of LPS to prime PMN, indicating that the priming activity of LPS is independent of LPS-induced TNF-alpha synthesis. The mechanism by which LPS enhance 5-LO product synthesis in PMN was investigated. Treatment of PMN with LPS strongly enhanced the release of arachidonic acid after stimulation with FMLP. The release of arachidonic acid was optimal 2-3 min after stimulation with FMLP, attaining levels 5-15-fold greater than those observed in unprimed cells stimulated with FMLP. These results demonstrate that LPS dramatically increases the ability of blood to generate 5-LO products, and support the putative role of leukotrienes in pathological states involving LPS.
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PMID:Lipopolysaccharides prime whole human blood and isolated neutrophils for the increased synthesis of 5-lipoxygenase products by enhancing arachidonic acid availability: involvement of the CD14 antigen. 769 Aug 33

The activation of the respiratory burst by complement factor 5a (C5a), platelet-activating factor (PAF), formyl-Met-Leu-Phe (fMLP) and neutrophil-activating peptide IL-8 was explored in eosinophils from patients with the hypereosinophilic syndrome. The amplitude of the response increased with increasing concentrations of C5a and PAF, but the time for its induction was unaffected by the amount of stimulus applied. Respiratory burst activity resulting from phorbol 12-myristate, 13-acetate (PMA)-mediated activation of protein kinase C (PKC) produced longer onset times, which shortened with increasing PMA concentrations. Total inhibition of the C5a- and PMA-mediated burst could be achieved with the PKC inhibitor staurosporine at concentrations of 100 and 5nM, respectively. Calcium depletion abolished agonist-induced rises in cytosolic free calcium ([Ca2+]i) and respiratory burst activity, but not PMA-mediated NADPH-oxidase activation. While PMA reduced elevations in [Ca2+]i, it restored the burst response to agonists in Ca(2+)-depleted eosinophils. These results agree with the agonist-induced activation of the NADPH-oxidase via PKC, but suggest a parallel, Ca(2+)-, phospholipase C- and PKC-independent signal transduction pathway. Data obtained with B. pertussis toxin showed that the respiratory burst in eosinophils is blocked by ADP-ribosylation of G(i)-proteins, but that in the presence of PMA portions of the agonist response could be recovered.
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PMID:Activation of the respiratory burst in eosinophil leucocytes--a transduction sequence decoupled from cytosolic Ca2+ rise. 770 83

We have examined the capacity of four different chemoattractants/cytokines to promote directed migration of polymorphonuclear leukocytes (PMN) through three-dimensional gels composed of extracellular matrix proteins. About 20% of PMN migrated through fibrin gels and plasma clots in response to a gradient of interleukin 8 (IL-8) or leukotriene B4 (LTB4). In contrast, < 0.3% of PMN migrated through fibrin gels in response to a gradient of tumor necrosis factor alpha (TNF) or formyl-methionyl-leucyl-phenylalanine (FMLP). All four chemoattractants stimulated PMN to migrate through gels composed of collagen IV or of basement membrane proteins (Matrigel), or through filters to which fibronectin or fibrinogen had been adsorbed. PMN stimulated with TNF or FMLP adhered and formed zones of close apposition to fibrin, as measured by the exclusion of a 10-kD rhodamine-polyethylene glycol probe from the contact zones between PMN and the underlying fibrin gel. By this measure, IL-8- or LTB4-treated PMN adhered loosely to fibrin, since 10 kD rhodamine-polyethylene glycol permeated into the contact zones between these cells and the underlying fibrin gel. PMN stimulated with FMLP and IL-8, or FMLP and LTB4, exhibited very little migration through fibrin gels, and three times as many of these cells excluded 10 kD rhodamine-polyethylene glycol from their zones of contact with fibrin as PMN stimulated with IL-8 or LTB4 alone. These results show that PMN chemotaxis is regulated by both the nature of the chemoattractant and the composition of the extracellular matrix; they suggest that certain combinations of chemoattractants and matrix proteins may limit leukocyte movements and promote their localization in specific tissues in vivo.
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PMID:Fibrin regulates neutrophil migration in response to interleukin 8, leukotriene B4, tumor necrosis factor, and formyl-methionyl-leucyl-phenylalanine. 772 53

Optical microscopy and image processing have been employed to study the distribution of several cell surface receptors on living human neutrophils during opsonin-dependent and opsonin-independent phagocytosis. Receptors were labeled using fluorescein-, rhodamine-, or AMCA-conjugated F(ab')2 fragments of anti-Fc gamma RIIIB (CD16), anti-CR3 (CD11b/CD18), and anti-uPAR (urokinase-type plasminogen activator receptor) antibodies, intact phycoerythrin-labeled interleukin 8, and fluorescein- or rhodamine-labeled Con A (concanavalin A), Boc-PLPLP (tert-butyl-oxycarbonyl-Phe(D)-Leu-Phe(D)-Leu-Phe-OH), and N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys. Labeled neutrophils were observed during the phagocytosis of IgG-opsonized erythrocytes and nonopsonized latex beads, Escherichia coli, and Staphylococcus aureus. To quantitate receptor distribution, cells were divided into four quadrants with the first being the point of attachment and the fourth being opposite the point of attachment. Ligated formyl peptide receptors, and to a lesser extent CR3, accumulated at the sites of target internalization for all forms of phagocytosis examined. However, Fc gamma RIIIB, uPAR, IL-8, Con A, and the FPR antagonist FBoc-PLPLP were not polarized on cells during phagocytosis. These data suggest that agonist-labeled formyl peptide receptors may play a broader role in leukocyte function than previously suggested, including possible participation in phagocytosis.
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PMID:Imaging the spatial distribution of membrane receptors during neutrophil phagocytosis. 773 43

Endothelin-1 (ET-1) is a vasoconstrictive peptide released by ischemic/injured endothelium which increases intracellular ionized calcium [Ca2+]i in vascular smooth muscle. Previous work from this lab has shown that ET-1 also increases human peripheral blood monocyte [Ca2+]i, and that 24 h incubation of monocytes with 10(-9) M ET-1 causes production of prostaglandin E2 and interleukin-6. In these studies, ET-1-stimulated monocyte supernatants were evaluated for their effect on neutrophil superoxide production. While ET-1 alone had no direct effect, incubation of neutrophils for 20 min in ET-1-stimulated monocyte supernatants resulted in a 10-fold increase in superoxide production over basal levels, 44% as much superoxide production as induced by peptide N-formyl-methionyl-leucyl-phenylalanine (N = 6, p < .001). Monocyte supernatants were analyzed for interleukin-8 (IL-8 or neutrophil activation protein) content by radioimmunoassay. ET-1-stimulation resulted in production of 54% as much IL-8 as lipopolysaccharide controls (N = 6, p < .001). While a number of monokines can activate neutrophils, IL-8 has been shown to be a potent neutrophil activator as well as a superoxide primer. Therefore, ET-1-treated monocytes probably upregulate neutrophil superoxide production via a mechanism which includes IL-8.
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PMID:Endothelin-stimulated monocyte supernatants enhance neutrophil superoxide production. 773 49

Molecules representative of different classes of chemotactic agents, including formyl-Met-Leu-Phe (FMLP), C5a, leukotriene B4, platelet-activating factor, and interleukin (IL)-8, caused a rapid reduction in the IL-1 binding capacity by human polymorphonuclear leukocytes (PMN), a cell type expressing predominantly the IL-1 type II decoy receptor (IL-1 decoy RII). N-t-Boc-Met-Leu-Phe, an antagonist for the FMLP receptor, inhibited the loss of IL-1 binding capacity induced by FMLP. Monocyte chemotactic protein 1, a chemokine related to IL-8 but inactive on PMN, had no effect on IL-1 binding in this cell type. FMLP was selected for further detailed analysis of chemoattractant-induced loss of IL-1 binding by PMN. The action of FMLP was rapid, reaching 50% of its maximum (80%) at 30 s, the earliest measurable time point, and plateauing between 10 and 30 min. Dose-response analysis revealed that maximal reduction of IL-1 binding was reached at FMLP concentrations that were also optimal for chemotaxis (50% effective dose = 5 x 10(-9) M). The loss of IL-1 binding capacity caused by FMLP was determined by a reduction in receptor number with no change in their affinity. The effect of FMLP on IL-1 receptor (IL-1R) was selective in that the PMN surface structures IL-8R, CD16, CD18, and major histocompatibility complex class I antigens were unaffected under these conditions. Loss of surface IL-1R was not due to an augumented rate of internalization. FMLP caused rapid release of a 45-kD IL-1-binding molecule identified as the IL-1 decoy RII. After FMLP-induced release, PMN reexpressed newly synthesized receptors, reaching basal levels by 4 h. FMLP-induced release of the IL-1 decoy RII did not impair the responsiveness of PMN to IL-1 in terms of promotion of survival and cytokine production. FMLP-induced release of the IL-1 decoy RII was unaffected by protein synthesis inhibitors, was blocked by certain protease inhibitors, and was mimicked by agents (the Ca++ ionophore A23187 and phorbol myristate acetate) that recapitulate elements in the signal transduction pathway of chemoattractant receptors. The time frame and concentration range of chemoattractant-induced rapid release of the IL-1 decoy RII are consistent with the view that IL-1 decoy RII release is an early event in the multistep process of leukocyte recruitment.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Chemoattractants induce rapid release of the interleukin 1 type II decoy receptor in human polymorphonuclear cells. 776 5

Physiological levels of human fibrinogen markedly inhibited the chemotactic activity of human neutrophils triggered by zymosan-activated serum (ZAS), C5a, or IL-8 in a Boyden chamber assay. Fibrinogen also slightly inhibited the N-formyl-methionyl leucyl-phenylalanine (FMLP)-induced migration of human neutrophils. Albumin was devoid of the inhibitory activities displayed by fibrinogen in this system. The inhibition of chemotaxis by fibrinogen was dose-dependent and saturable. Fibrinogen placed in the upper compartment of the Boyden chamber produced a larger inhibition than that obtained with fibrinogen placed in the lower compartment. Lysine as well as the lysine analog 6-aminohexanoic acid (AHA) decreased the inhibitory capacity of fibrinogen. In contrast, both arginine and glutamine failed to suppress the fibrinogen-mediated inhibition of neutrophil chemotaxis. AHA counteracts the inhibition of ZAS-induced chemotaxis by anti-CD18 monoclonal antibody, suggesting that lysine binding sites are required for integrin function in chemotaxis. Fibrinogen also inhibited, in a dose-dependent manner, the oxygen consumption of neutrophils activated by opsonized zymosan. Taken together, the present results indicate that fibrinogen modulates neutrophil functions and suggest that in addition to its role in blood coagulation, circulating fibrinogen may be involved in regulation of the inflammatory response.
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PMID:Inhibition of neutrophil activation by fibrinogen. 784 97

Analysis of synthetic tri- and tetrapeptides has previously indicated that N-formylation is required for high biological activity when they react with the phagocyte N-formylpeptide receptor, suggesting that the natural ligand for the receptor is from bacterial and/or mitochondrial sources. To explore this requirement further, we synthesized the pentapeptide methionyl-norleucyl-leucyl-phenylalanyl-phenylalanine (MNleLFF) and studied the effects of different NH2-terminal modifications on its activity. N-formyl-MNleLFF induced transient alterations of [Ca2+]i and superoxide production in human neutrophils with 10- and 100-fold greater potency, respectively, than the proto-type N-formylpeptide, N-formylmethionyl-leucyl-phenylalanine (fMLF). Surprisingly, N-acetyl-MNleLFF was a potent as N-formyl-MNleLFF. Moreover, the unacylated counterpart H-MNleLFF was also highly active, having an EC50 for calcium mobilization of 10 nM, and for respiratory burst activation of 100 nM. All three pentapeptides could completely desensitize calcium transients elicited by stimulation of neutrophils with fMLF, whereas the neutrophil chemoattractants C5a and interleukin 8 only weakly affected fMLF-induced transients, suggesting that they activate neutrophils via the same receptor as fMLF. Finally, all three pentapeptides activated the recombinant human N-formylpeptide receptor expressed in frog oocytes, but did not effectively activate related phagocyte receptors. These data broaden the potential sources of natural ligands for the N-formyl-peptide receptor from N-formylated bacterial and mitochondrial products to other nonformylated endogenous peptides.
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PMID:A high potency nonformylated peptide agonist for the phagocyte N-formylpeptide chemotactic receptor. 796 94

We examined the biological and kinetic characteristics of two new members of the intercrine family of cytokines. Human macrophage inflammatory peptides 2 alpha and beta (huMIP-2 alpha and beta) were compared to human interleukin 8 (huIL-8), neutrophil activating peptide 2 (huNAP-2), and N-formyl-L-methionyl-L-phenylalanine (fMLP). The huMIP-2 peptides were the least potent cytokine tested in triggering neutrophil degranulation. They were also less potent neutrophil chemotaxins than fMLP or huIL-8. However, they were more effective than NAP-2 in stimulating chemotaxis of neutrophils. The binding studies showed that huMIP-2 peptides could interact with specific receptors on human blood neutrophils. Moreover, huMIP-2 peptides competed for up to 60% of the huIL-8 binding sites on neutrophils whereas huIL-8 competed for almost 100% of either of the huMIP-2 peptide binding sites. These data suggest the huMIP-2 peptides have little or no affinity for 40% of the huIL-8 receptors. In addition, detectable amounts of mRNA for huMIP-2 alpha were found in samples from human alveolar macrophages stimulated with Staphylococcus aureus, toxic shock syndrome toxin-1 (TSST), but not in samples stimulated with S. aureus enterotoxin A (SEA) or Escherichia coli endotoxin (lipopolysaccharide = LPS). In conclusion, huMIP-2 alpha and beta are weak neutrophil stimulating agents, which may increase inflammation in diseases such as toxic shock syndrome.
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PMID:Biological and kinetic characterization of recombinant human macrophage inflammatory peptides 2 alpha and beta and comparison with the neutrophil activating peptide 2 and interleukin 8. 803 95


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