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) is a member of the CXC branch of the chemokine superfamily and activates neutrophils but not monocytes. The related CC chemokine branch, which includes monocyte chemoattractant protein-1 (MCP-1) and RANTES are potent chemoattractants for monocytes but not neutrophils. Examination of the sequences of the CXC chemokines reveals that the highly conserved leucine, corresponding to Leu25 in IL-8, is always replaced by tyrosine in CC chemokines. There is also a high degree of conservation among the CXC chemokines of the adjacent Val27 residue, which points out from the same side of the beta-sheet as Leu25. In RANTES, Val27 is also replaced by a tyrosine. In order to investigate the role of these residues in controlling cell specificity, we have made the single mutants Leu25-->Tyr, Val27-->Tyr and the double mutant Leu25-->Tyr, Val27--> Tyr of IL-8. These proteins have been expressed in Escherichia coli and purified to homogeneity from inclusion body material. All three mutants have lower potency and efficacy in chemotaxis and calcium mobilization assays using neutrophils. The mutants also show lowered affinity to both IL-8 receptors A and B expressed recombinantly in HL-60 cells and to neutrophils in [125I]IL-8 competition assays. Additionally, the Leu25-->Tyr mutation introduces a novel monocyte chemoattractant activity into IL-8. We therefore studied the displacement of [125I]MIP-1 alpha by IL-8 Leu25-->Tyr from the CC-CKR-1 receptor. The mutant displaces MIP-1 alpha ligand with an affinity only 12-fold less than MIP-1 alpha itself. This suggests that mutations in this region of IL-8 are involved in receptor binding and activation and in the control of specificity between CC and CXC chemokines.
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PMID:Mutation of Leu25 and Val27 introduces CC chemokine activity into interleukin-8. 753 92

Emigration of leukocytes at sites of inflammation is initiated by the selectin family of carbohydrate-binding adhesion molecules. Molecular crossbridges initiate rolling of cells along the vascular endothelium where chemokines such as IL-8 and platelet activating factor (PAF) may be presented to their receptors on the leukocyte surface resulting in cell stimulation. Integrin activation appears to be a requirement for subsequent cell localization and diapedesis into the tissue. Several recent reports have demonstrated that ligation and cross-linking of neutrophil L-selectin results in neutrophil activation, including intracellular calcium release, superoxide production, and induction of mRNA for production of IL-8 and TNF-alpha. The purpose of this study was to examine whether ligation and cross-linking of L-selectin would specifically result in activation of beta 2-integrin-dependent adhesion. A fluorescence flow cytometric assay was developed that directly measures Mac-1-dependent cell adhesion. Fluorescent latex beads (2-microns diameter) were adsorbed with albumin or fibrinogen and added in excess to human neutrophils in a shear-stirred suspension. Following stimulation the kinetics of bead capture by neutrophils was continuously measured in real time on the flow cytometer. The onset of bead binding was detected in the presence of extremely low concentrations of PAF (10 pM) or formyl peptide (0.2 nM) stimulation. Ligation of L-selectin with whole IgG DREG200 or DREG56 Ab, but not controls (anti-CD44, -CD45, -CD11a), resulted in a significant potentiation of bead binding. Cross-linking F(ab')2 fragments of DREG200 with a goat anti-mouse F(ab')2 secondary Ab also stimulated beta 2-integrin-dependent adhesion in a dose-dependent fashion. A chimeric form of DREG200 expressing gamma 4 or gamma 1 isotypes of human Fc domain also stimulated cell adhesion when cross-linked. Surface expression of CD18 and an activation-dependent epitope, as detected with mAb24, also increased in response to L-selectin cross-linking. Cross-linking L-selectin induced significant adhesion and transmigration of neutrophils across human umbilical vein endothelial cells. We propose that cross-linking of L-selectin results in a cell signal that directly stimulates beta 2-integrin adhesive responses.
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PMID:L-selectin (CD62L) cross-linking signals neutrophil adhesive functions via the Mac-1 (CD11b/CD18) beta 2-integrin. 754 24

It has been established that IL-8 triggers angiogenesis in vivo, but this effect may be mediated either by IL-8-recruited leukocytes or by direct actions of IL-8 upon endothelial cells (EC). We have approached this question by examining interactions of recombinant human IL-8 with cultured large vessel and microvascular human EC. We are unable to detect specific IL-8 binding to cultured human umbilical vein endothelial cells (HUVEC) or leukocyte-like IL-8 receptor mRNA expression by either cultured HUVEC or human dermal microvascular endothelial cells (DMEC). We find no alteration of cytoplasmic calcium concentration ([Ca2+]i) in either cell type in response to IL-8 treatment. Finally, we find no IL-8-induced change in EC proliferative rates in the presence or absence of endothelial cell growth factor. Our data favour an indirect action for IL-8 as an angiogenic factor.
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PMID:IL-8 and angiogenesis: evidence that human endothelial cells lack receptors and do not respond to IL-8 in vitro. 754 79

All-trans retinoic acid (ATRA) is a differentiating agent that has been successfully used in the treatment of patients with acute promyelocytic leukemia (APL). Functional properties of peripheral blood neutrophils from a patient with APL during treatment with ATRA have been studied. Wright stain of patient neutrophils showed hypogranulation and loose nuclear chromatin when compared with normal neutrophils. These cells were of lower density than normal neutrophils and separated on density gradient centrifugation with mononuclear cells. Surface antigen expression by FACS distinguished these cells from lymphocytes. The histograms showed a population of larger cells expressing CD18 and CD11b, distinct from the smaller cells which did not express CD11b. fMLP caused an increase in intracellular calcium (measured spectrophotometrically) that was inhibited by the calcium chelator BAPTA. Actin polymerization following cell activation was measured using NBD-phallacidin staining and FACS. Both IL-8 and fMLP caused rapid increases using F-actin content (2.5-3.0 fold), which were of greater magnitude than generally seen with normal neutrophils. Treatment with BAPTA before activation with fMLP did not blunt the actin responses, despite complete inhibition of an intracellular calcium increase. In summary, neutrophils derives from differentiated APL cells express CD18/CD11b, and exhibit a similar degree of actin polymerization in response to fMLP and IL-8, independent of an increase in intracellular calcium. Although the actin responses are greater than normal neutrophils, most properties are similar, supporting the contention that these cells can protect the host. The exaggerated actin response to inflammatory mediators, however, may play a role in the 'retinoic acid syndrome'.
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PMID:Functional characteristics of mature granulocytes in a patient with acute promyelocytic leukemia treated with all-trans retinoic acid. 754 48

The effect of cytokines, growth factors, mitogens, and bacterial products on nitric oxide (NO) generation by monolayers of small intestinal epithelial cells-6 (IEC-6) cells was evaluated. Subconfluent IEC-6 cells were maintained in DMEM containing 5% fetal calf serum and after 16-24 hr of incubation, the medium was replaced with fresh medium in the presence or absence of calcium ionophore (CaI), L-NAME, L-NNA, individual growth factors, cytokines, or mitogens. After 72 hr of culture, the media supernatant was collected and NO chi generation was determined. NO synthase activity was determined in sonicated supernatants of IEC-6 cells by [14C] arginine conversion to citrulline. NO chi generation in subconfluent cultures was greater than in fully confluent cultures, suggesting contact inhibition. NO chi generation by IEC-6 cells was significantly increased by CaI and inhibited by L-NAME and L-NNA. LPS, IL-1 beta, IL-2, IL-8, IFN-8, TFN-alpha, EGF, TGF-alpha, bFGF, and PHA significantly increased NO chi generation. NO synthase activity in IEC-6 cells (4.2 +/- 1.7 pmol/min/10(6) cells) was NADPH dependent. These results suggest that stimulation of NO chi generation by intestinal epithelial cells through cytokine bacterial products and mitogens may be one of the mechanisms responsible for their effects in the intestinal tract.
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PMID:NO chi generation by cultured small intestinal epithelial cells. 755 34

Adenosine potentiates mast cell activation, but the receptor type and molecular mechanisms involved have not been defined. We, therefore, investigated the effects of adenosine on the human mast cell line HMC-1. Both the A2a selective agonist CGS21680 and the A2a/A2b nonselective agonist 5'-N-ethylcarboxamidoadenosine (NECA) increased cAMP, but NECA was fourfold more efficacious and had a Hill coefficient of 0.55, suggesting the presence of both A2a and A2b receptors. NECA 10 microM evoked IL-8 release from HMC-1, but CGS21680 10 microM had no effect. In separate studies we found that enprofylline, an antiasthmatic previously thought to lack adenosine antagonistic properties, is as effective as theophylline as an antagonist of A2b receptors at concentrations achieved clinically. Both theophylline and enprofylline 300 micro completely blocked the release of IL-8 by NECA. NECA, but not CGS21680, increases inositol phosphate formation and intracellular calcium mobilization through a cholera and pertussis toxin-insensitive mechanism. In conclusion, both A2a and A2b receptors are present in HMC-1 cells and are coupled to adenylate cyclase. In addition, A2b receptors are coupled to phospholipase C and evoke IL-8 release. This effect is blocked by theophylline and enprofylline, raising the possibility that this mechanism contributes to their antiasthmatic effects.
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PMID:Adenosine A2b receptors evoke interleukin-8 secretion in human mast cells. An enprofylline-sensitive mechanism with implications for asthma. 756 91

Trafficking to tissues and then to lymph nodes is a crucial aspect of the immunobiology of dendritic cells. The present study was designed to identify molecules able to direct the migration of human blood-derived dendritic cells. fMLP (representative of formyl peptides of bacterial origin), C5a, and the C-C chemokines monocyte chemotactic protein (MCP)-3, MIP-1 alpha/LD78, and RANTES elicited chemotactic migration and a rise of intracellular free calcium in dendritic cells. In contrast, the C-X-C chemokines IL-8 and IP-10 and the C-C chemokines MCP-1 and MCP-2 were inactive as chemoattractants. Thus, dendritic cells respond to classical chemotactic signals and to a set of chemokines distinct from that active on monocytes and neutrophils. Chemoattractants are likely to contribute to localization and trafficking of dendritic cells and provide tools to recruit these cells in the design of immunization strategies.
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PMID:Migration of dendritic cells in response to formyl peptides, C5a, and a distinct set of chemokines. 756 Oct 21

Interleukin-8, a neutrophil chemotactic agent, is known to have an active role in the induction of inflammatory response in a number of diseases. Although the activity of IL-8 is known to be through a receptor (IL-8R) on the surface of neutrophils, no information is available regarding the regulation of the IL-8R expression. The present study demonstrates that serum activated LPS at a concentration of 10 ng/ml induces expression of functionally active IL-8R by 120% within 30 min through de novo protein synthesis. The upregulated receptors could be detected by anti-IL-8R antibody and could also be demonstrated by autoradiography with crosslinking 125I IL-8. The serum-activated LPS-stimulated neutrophils migrated faster and showed higher Ca2+ flux over the unstimulated cells. The LPS-induced receptors were downregulated rapidly, about 85% of the receptor activity being lost within 90 min of incubation at 37 degrees C. The downregulation could be partially prevented by treatment with a cocktail of protease inhibitors, suggesting the possible involvement of protease(s) in this process. Both EDTA (100 microM) and bestatin (40 microM) afforded almost complete protection of the receptor from proteolytic cleavage indicating that the enzyme involved is a metalloprotease, possibly an aminopeptidase. The study shows that stimulation of PMNs with LPS leads to induction of IL-8R expression enhancing the IL-8-mediated biological responses and also provides evidence for post-stimulatory restoration of receptor level on the neutrophil surface by proteolytic cleavage of the amino-terminal end of the receptor.
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PMID:Regulation of interleukin-8 receptor expression in human polymorphonuclear neutrophils. 756 15

The human type A interleukin-8 receptor (IL-8RA) was modified to express an amino-terminal epitope tag and stably overexpressed in a rat basophilic leukemia cell line (RBL-2H3). This receptor (ET-IL-8RA) displayed functional properties similar to those of the native receptor in neutrophils in that exposure to IL-8 stimulated GTPase activity, phosphoinositide (PI) hydrolysis, intracellular calcium mobilization, and degranulation in a pertussis toxin (PTx) susceptible fashion. IL-8 induced dose- and time-dependent phosphorylation of ET-IL-8RA. Phorbol 12-myristate 13-acetate (PMA) treatment also resulted in phosphorylation of the receptor although to a lesser extent. Staurosporine totally blocked PMA-induced phosphorylation but only partially inhibited IL-8-mediated phosphorylation. Phosphorylation of ET-IL-8RA correlated with its desensitization as measured by GTPase activation and calcium mobilization. To determine the role of phosphorylation in IL-8RA signal transduction, three mutants lacking specific serine and threonine residues located at the C-terminal of this receptor were constructed by site-directed mutagenesis (M1, M2, and M3). The mutated receptors expressed in RBL-2H3 cells displayed pharmacological properties (Kd approximately 2-2.8 nM and Bmax approximately 3-3.5 pmol/mg of protein) similar to those of the wild-type ET-IL-8RA. M2 and M3, but not M1, showed a marked decrease in IL-8-induced phosphorylation compared to the wild-type receptor. M2 and M3 but not M1 were resistant to PMA-mediated phosphorylation and desensitization and were also more resistant to homologous desensitization than M1 or ET-IL-8RA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of human interleukin-8 receptor A: identification of a phosphorylation site involved in modulating receptor functions. 757 17

Human neutrophils are able to kill in vitro colorectal carcinoma cell line SW11-16 coated with mAb 17-1A, but they are not cytotoxic towards a non-immunized tumour target. Neutrophil exposure to the inflammatory cytokine, IL-8, produces a significant increase in antibody-dependent cellular cytotoxicity, which is related to IL-8 concentration. Oxyradical production is one of the lytic mechanisms used by phagocytes, and IL-8 is shown to activate this function, which does not occur if neutrophils are pretreated with the protein kinase C inhibitor, staurosporine, but is increased by R59022, a dyacylglycerol kinase inhibitor. The IL-8 effect is mediated by protein kinase C, which is potentiated by the calcium flux induced by the interaction between antibody coating tumour target and Fc gamma RIII on effector cells, as previously demonstrated. Data suggest a possible new role for IL-8 in tumour surveillance.
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PMID:IL-8 enhances antibody-dependent cellular cytotoxicity in human neutrophils. 759 Aug 96


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