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)

Interleukin-8 (IL-8) plays a crucial role in the pathogenesis of inflammatory and hyperproliferative diseases in various organs. The purpose of the present investigation was to establish whether there is any naturally occurring inhibitor of IL-8. Here we demonstrate that an IL-8 inhibitor (IL-8INH) is present in the supernatant of polymorphonuclear (PMN) leukocytes. The release of IL-8INH could be increased by stimulating the PMN leukocytes by concanavalin A. IL-81NH blocks the IL-8-induced chemotaxis and Candida albicans killing activity of PMN leukocytes and epidermal cells in vitro, and IL-8-induced neutrophil infiltration in the mouse ear in vivo. The mechanism of action of IL-8INH involves blocking of 125I-IL-8 binding to the IL-8 receptor. Binding of 125I-IL-8 to neutrophils could not be displaced by the IL-8INH, however, preincubation of 125I-IL-8 with IL-8INH increased binding inhibition, suggesting an interaction between IL-8 and the inhibitor. Crosslinking of 125I-IL-8 to IL-8INH shows that IL-8INH binds specifically to 125I-IL-8, and the IL-8INH protein has an apparent molecular weight of 52 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The partial purification of the IL-8INH on DEAE-Sephadex anion-exchange chromatography column also suggests a 50-60-kDa inhibitor protein which blocks IL-8-induced effects on neutrophils by binding to IL-8.
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PMID:Identification of a soluble interleukin-8 inhibitor in the supernatant of polymorphonuclear leukocytes. 986 98

Neutrophils (polymorphonuclear neutrophils; PMN) and a redundant system of chemotactic cytokines (chemokines) have been implicated in the pathogenesis of the acute respiratory distress syndrome in patients with sepsis. PMN express two cell surface receptors for the CXC chemokines, CXCR1 and CXCR2. We investigated the expression and function of these receptors in patients with severe sepsis. Compared with normal donors, CXCR2 surface expression was down-regulated by 50% on PMN from septic patients (p < 0.005), while CXCR1 expression persisted. In vitro migratory responses to the CXCR1 ligand, IL-8, were similar in PMN from septic patients and normal donors. By contrast, the migratory response to the CXCR2 ligands, epithelial cell-derived neutrophil activator (ENA-78) and the growth-related oncogene proteins, was markedly suppressed in PMN from septic patients (p < 0.05). Ab specific for CXCR1 blocked in vitro migration of PMN from septic patients to IL-8 (p < 0.05), but not to FMLP. Thus, functionally significant down-regulation of CXCR2 occurs on PMN in septic patients. We conclude that in a complex milieu of multiple CXC chemokines, CXCR1 functions as the single dominant CXC chemokine receptor in patients with sepsis. These observations offer a potential strategy for attenuating adverse inflammation in sepsis while preserving host defenses mediated by bacteria-derived peptides such as FMLP.
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PMID:Expression and function of the chemokine receptors CXCR1 and CXCR2 in sepsis. 997 13

Interleukin-8 (IL-8) production in vivo was monitored in four study groups: normal blood donors, patients with pulmonary tuberculosis (TB), patients with human immunodeficiency virus type 1 (HIV-1) infection, and dually infected (HIV/TB) patients. We show that whereas there was evidence of detectable levels of cell-associated IL-8 (mRNA and protein) in peripheral cells of healthy individuals, this was largely lost in the disease states studied. Coupled with this finding was significantly increased circulating levels of IL-8 in HIV-1-infected individuals with or without concomitant pulmonary TB (P < 0.001). On the other hand, the capacity of peripheral mononuclear cells to produce IL-8 spontaneously ex vivo was enhanced in HIV-1 and TB patients (P < 0.05) and many of the HIV/TB group, but their corresponding capacities to respond to various stimuli, in particular phytohemagglutinin, were significantly diminished compared to those of normal donors (P < 0.05). Circulating levels of IL-8 in a group of HIV/TB patients were significantly positively correlated with the percentage of polymorphonuclear leukocytes (PMN) in the peripheral circulation (r = 0.65; P = 0.01), the proportions of IL-8 receptor A (IL-8RA)-expressing (r = 0.86; P < 0.01) and IL-8RB-expressing (r = 0.77; P < 0.01) PMN, and the capacity of PMN to migrate in response to IL-8 as chemoattractant (r = 0.68; P < 0. 01). IL-8RB fluorescence intensity, however, was negatively correlated with plasma IL-8 levels (r = -0.73; P < 0.01). Our results suggest that altered regulation of IL-8 in HIV-1 may have important implications for antimicrobial defenses and for normal immune processes.
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PMID:Dysregulated production of interleukin-8 in individuals infected with human immunodeficiency virus type 1 and Mycobacterium tuberculosis. 1002 68

The chemokine is a new class of cytokine. Now, more than 30 members of chemokine superfamily and 15 members of chemokine receptors (CXCR1-4, CCR1-8, CX3CR, CCR) have been identified. They were shown to be involved in the inflammatory response. The chemokine is classified into four subgroups (CXC, CC, C and CX3C). The local production of IL-8, MCP-1 and RANTES in rheumatoid inflamed joints has been reported. The predominance of several chemokines in other collagen diseases, such as SLE, systemic sclerosis and myositis is also described. Therefore, the inhibition of chemokines or chemokine receptors might be novel targets for various human disease, including collagen diseases.
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PMID:[Chemokines and Chemokine receptors in collagen diseases]. 1007 91

Interleukin-8 (IL-8) is an important mediator of neutrophil (PMN) function and the type A IL-8 receptor (IL-8RA) mediates these pro-inflammatory signals. Hypoxia or hypoxia/reoxygenation (H/R) affects the production of IL-8, but no data is available regarding its effect on IL-8RA expression. The purpose of this study was to determine the effects of hypoxia and/or H/R on the expression of IL-8RA in PMN. We demonstrated that IL-8RA mRNA levels were similar under normoxic and hypoxic conditions but H/R resulted in a significant reduction in mRNA expression between 30 and 60 min. IL-8RA protein also decreased with reoxygenation of whole blood, which was altered by the addition of specific antioxidants. Therefore, H/R appears to attenuate the effect of IL-8 by down-regulating IL-8RA in PMN. These data show that changes in oxygen tension within the wound site not only affect the expression of inflammatory cytokines, but also control their actions by regulating their receptors.
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PMID:Regulation of IL-8RA (CXCR1) expression in polymorphonuclear leukocytes by hypoxia/reoxygenation. 1008 99

Interleukin-8 (IL-8), a pro-inflammatory chemokine, induces trafficking of neutrophils across the vascular wall. The release of IL-8 is triggered by inflammatory signals from a large variety of cells. The diversity in the cellular source indicates pleiotropy of its functions. IL-8 plays a key role in host defense mechanism through its effects on neutrophil activation, but a continued presence of IL-8 in circulation in response to inflammatory conditions may lead to a variable degree of tissue damage. Like most of the peptide hormones or mediators, IL-8 transmits its signals through distinct cell surface receptors. The membrane spanning heptahelical IL-8 receptor is coupled with the effector enzyme(s) through the intermediacy of heterotrimeric GTP-binding regulatory proteins. A growing number of studies demonstrated regulation of IL-8 activity by pertussis toxin treatment, implying a role of pertussis toxin sensitive G proteins (Gi), in IL-8 induced effects. IL-8 induced activation of G-protein results in activation of phospholipase C b2 (PLCb2). This enzyme catalyzes the hydrolysis of membrane phosphoinositides to yield diacylglycerol (DAG) and inositol 1,4,5 trisphosphate (IP3), which in turn activates protein kinase C (PKC) and mobilizes the intracellular Ca2+, respectively. Neutrophils activation of phospholipase D (PLD) and superoxide generation in response to IL-8 have also been demonstrated. Furthermore, IL-8-mediated activation of mitogen activating protein kinase (MAPK) and tyrosine phosphorylation of cellular proteins have been observed. It appears that the signalling pathways induced by IL-8 are subject to fine modulations by the demand and presence of IL-8. The presence of IL-8 in various pathophysiological condition implies that blockade of its actions could be exploited for therapeutic purposes.
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PMID:Interleukin-8: An autocrine inflammatory mediator. 1010 Dec 23

In this study, we have explored the mechanism for the desensitization of IL-8-mediated neutrophil chemotaxis by a cell-binding fragment of fibronectin (120-kDa FN). Preincubation of neutrophil suspensions with the 120-kDa FN fragment resulted in a heterologous desensitization of IL-8-mediated chemotaxis while not affecting neutrophil chemotaxis to either fMLP or zymosan-activated serum. Preincubation of neutrophils with the beta1-integrin-activating antibody (TS2/16) mimicked the effects of the 120-kDa FN fragment while preincubating neutrophils with the beta1-integrin blocking antibody (mAb13) abrogated the inhibitory effects of the 120-kDa FN fragment on IL-8-mediated chemotaxis. Furthermore, we also demonstrated that the 120-kDa FN fragment did not inhibit chemotaxis to the CXC chemokine MGSA/GROalpha which interacts with high affinity to the IL-8 receptor B (CXCR2). By in vivo phosphorylation of neutrophils and probing lysates with an anti-CXCR1 antibody, we demonstrated that the addition of the cell-binding fragment of fibronectin resulted in a time-dependent phosphorylation of CXCR1. These findings suggest that the mechanism of heterologous desensitization of IL-8-mediated chemotaxis following ligation of FN-dependent integrins is the result of phosphorylation of the CXCR1 receptor.
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PMID:Heterologous desensitization of IL-8-mediated chemotaxis in human neutrophils by a cell-binding fragment of fibronectin. 1020 81

Little is known about the mechanisms controlling the expression of key proteins that regulate excitability and contractility in the human myometrium at term. However, evidence is accumulating to suggest that the cytokine transforming growth factor (TGF)beta may play a central role. TGFbeta1 and TGFbeta receptors are present in the myometrial cells, indicative of an autocrine signaling system. Furthermore, the levels of TGFbeta1 and the expression of its receptors increase in the myometrium at term suggesting that they are, in turn, regulated and form part of a physiological cascade of events involving a number of autocrine signaling associated proteins. The present experiments were done to identify factors that regulate the expression of TGFbeta1 and TGFbeta receptors and may form other elements of this cascade. Because IL-1 and IL-8 are found in the myometrium at term and have been implicated in the etiology in premature labor we focus on this cytokines. Receptors for IL-1 and IL-8 were detected in the myometrial cells. Using Western blot analysis, the levels of expression were found to vary. The expression of IL-1 receptor type I was highest in the nonpregnant tissue with lower levels in nonlaboring myometrium with a further reduction in the spontaneously laboring tissue. In contrast, the expression of IL-8 receptor type B was highest in the pregnant nonlaboring tissue with a lower level in the spontaneously laboring tissue. Using an in vitro model, TGFbeta1 and TGFbeta receptor expression was up-regulated by IL-8, IL-1, and TGFbeta1 itself. However, IL-8 receptor expression was decreased by IL-8 and TGFbeta1. This suggests that in a cascade IL-8 would feed forward to promote the TGFbeta system, whereas TGFbeta1 feeds back to inhibit responsiveness to IL-8. Estrogen and progesterone increased the release of TGFbeta1. However, at high concentrations, estrogen and progesterone (100 nM 17beta-estradiol or 200 nM progesterone) decreased the level of TGFbeta receptor expression. Thus, the progressive rise of steroid levels in vivo might account for the observed changes in TGFbeta1 and TGFbeta receptor expression in vivo. Taken together, these observations support the idea that there is a cascade of autocrine signals that may play a major role in the physiological processes preparing the myometrium for parturition at term.
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PMID:Complex interactions between sex steroids and cytokines in the human pregnant myometrium: evidence for an autocrine signaling system at term. 1034 39

All leukocytes express the cell surface glycoprotein CD45, which has intrinsic intracellular protein tyrosine phosphatase activity. CD45 is known to play a regulatory role in activation-induced signaling in lymphocytes; however, little is known of its role in non-lymphoid leukocytes. Therefore, we examined the potential effect of CD45 on chemokine-induced signaling in human neutrophils (polymorphonuclear cells, PMN). Treating isolated PMN for 2 h with an anti-CD45RB antibody (Bra11) down-modulated expression of the chemokine receptors CXCR1 and CXCR2 to 44 +/- 10% and 47 +/- 9% of their respective controls. The tyrosine kinase inhibitors genistein and herbimycin A significantly inhibited the Bra11-induced down-modulation of CXCR1 and CXCR2. Furthermore, Bra11-treated PMN were functionally inhibited in their capacity to exhibit IL-8-induced transient intracellular Ca2+ increases. Selected targeting of CXC receptors is indicated by the fact that N-formyl-Met-Leu-Phe (fMLP) receptor expression and function were not lost following Bra11 treatment. The effect of Bra11 on IL-8-mediated function and receptor expression was paralleled by decreased tyrosine phosphorylation of a 54- to 60-kDa protein. These findings indicate that CD45 can act to modulate PMN responses to chemokines; thus agents regulating CD45 can potentially modulate leukocyte traffic and may represent a novel therapeutic approach towards the treatment of inflammatory diseases.
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PMID:CD45 modulation of CXCR1 and CXCR2 in human polymorphonuclear leukocytes. 1035

Engineering proteins to contain a histidine (His)-tag has proved to be very useful for the purification and analyses of these molecules. In the present study, we demonstrate that the binding of His-tagged ligands to their receptors may be visualised by flow cytometry making use of a selected monoclonal antibody (mAb) against the His-tag. Employing this method, a recombinant C3a (rC3a) anaphylatoxin with a His-tag at its N-terminus could be shown to bind to C3a receptor (C3aR)-expressing RBL-2H3 transfectants with a half-maximal effective concentration (EC50) of about 3 nM which is well within the range of published affinity constants. Binding of a recombinant interleukin-8 (rIL-8) molecule with a C-terminal His-tag to RBL-2H3 cells which stably express the IL-8 receptors CXCR1 or CXCR2 could also be demonstrated using the tag-specific mAb. Furthermore, aminoterminally tagged C5a molecules of rat or human origin could be shown to bind to the human C5a receptor (C5aR). However, the fluorescence signal of the binding of rat rC5a to the human C5aR was distinctly higher over a wide range of ligand concentrations than the signal of human rC5a binding although both ligands were equally potent in the induction of chemotaxis in C5aR-expressing cells. Thus, the tag-specific mAb was able to interfere with the binding of human but not rat rC5a to the human C5aR. This observation is in agreement with the hypothesis of a two binding site model for the interaction of human C5a with its receptor whereas a different binding mode may apply for rat C5a. Our data demonstrate that the selected His-tag specific mAb may be a valuable tool for the visualisation of the binding of recombinant ligands to their receptors and may also provide useful information on the specific binding properties of the ligands.
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PMID:Specific detection by flow cytometry of histidine-tagged ligands bound to their receptors using a tag-specific monoclonal antibody. 1041 Sep 79


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