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

The proopiomelanocortin-derived peptide alpha-melanocyte stimulating hormone (alpha-MSH) has potent anti-inflammatory effects in all animal models of inflammation against which it has been tested. Understanding of the mechanism by which this occurs is incomplete, although there is recent evidence for alpha-MSH receptors in murine and human macrophages and for modulation of production of proinflammatory cytokines and related mediators by alpha-MSH. Because of the prominence of neutrophils in early stages of inflammatory reactions where alpha-MSH is effective, we examined human neutrophils for evidence of mRNA for alpha-MSH receptors and for inhibition of neutrophil chemotaxis. There was accumulation of mRNA for melanocortin receptor 1 (MC1) in RT/PCR product from neutrophils stimulated with interferon and LPS. In subsequent studies alpha-MSH inhibited migration of neutrophils from most normal volunteers when the cells were placed in FMLP or IL-8 gradients. The inhibition by alpha-MSH could be traced to alterations in cAMP in neutrophils. The presence of alpha-MSH receptor message in neutrophils is consistent with the established anti-inflammatory effects of the peptide. Direct inhibition of neutrophil chemotaxis likely contributes to the anti-inflammatory activity of alpha-MSH.
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PMID:The neuropeptide alpha-MSH has specific receptors on neutrophils and reduces chemotaxis in vitro. 880 79

Interleukin-8 (IL-8) is an important cytokine in inflammatory processes by functioning as a chemoattractant and as an activator of oxygen metabolism. In the present study we demonstrate that beta 2-adrenergic agonists potentiate the lipopolysaccharide (LPS) and IL-1 induced production of IL-8 by human monocytes. In addition, beta 2-adrenergic activation enhances IL-8 release and mRNA expression for IL-8 in the human monocytic cell line U937. beta 2-adrenergic activation of these cells also results in enhanced production of the anti-inflammatory cytokine IL-10. However, IL-10 is not involved in the regulation of IL-8 production. The effect of the beta 2-adrenergic agonist on IL-8 production is presumably mediated via increased cAMP formation, since it can be mimicked by the cAMP analogue dibutyryl-cAMP (db-cAMP). We conclude that enhancement of IL-8 production is one of the pathways via which beta 2-adrenergic agonists such as catecholamines can influence inflammatory responses.
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PMID:Beta 2-adrenergic activation enhances interleukin-8 production by human monocytes. 925 52

Pentoxifylline (PTX) is a methylxanthine derivative used in a wide range of dermatoses. As well as its hemorrheologic activity, PTX has anti-inflammatory properties. Buflomedil chlorhydrate (BC) is another hemorrheological drug with peripheral vasodilatory action, whose clinical uses are similar to those of PTX. Both drugs increase intracellular levels of cAMP, either secondary to phosphodiesterase inhibition (PTX) or adenyl-cyclase stimulation (BC). Long-term cultures of normal human keratinocytes were prepared in a free-serum medium, and stimulated with 1 mg/ml of phorbol 12-myristate 13-acetate (TPA) and PTX or BC (100-1000 micrograms/ml). Levels of TNF-alpha, IL-1 alpha, IL-1 beta, IL-8 and TGF-beta 1 using ELISA and Northern blot or RT-PCR techniques were measured. TPA-induced TNF-alpha and IL-8 release from keratinocytes. TPA did not induce IL-1 alpha or IL-1 beta release of keratinocytes. TPA increased RNA expression of the TNF-alpha, IL-1 alpha, IL-1 beta, IL-8 and TGF-beta 1. BC diminished TPA-induced TNF-alpha and IL-8 release from keratinocytes; in the case of IL-8 it is possible that this inhibition occur to transcriptional level. Moreover PTX was unable to inhibit TNF-alpha and IL-8 synthesis and expression. PTX and BC reduced TPA-induced IL-1 alpha and beta expression. It is possible that BC action is specifically exerted on keratinocytes, because we did not find similar results with TNF-alpha and IL-8 synthesis in mononuclear peripheral blood cells.
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PMID:Differential modulation of IL-8 and TNF-alpha expression in human keratinocytes by buflomedil chlorhydrate and pentoxifylline. 929 91

1. The effects of cAMP-phosphodiesterase (PDE) isozyme inhibitors on the production of tumor necrosis factor alpha (TNF-alpha), and interleukins 1 beta 8 (IL-1 beta and IL-8) by lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (PBMC) were evaluated. In addition, we investigated the effects of dibutyryl cAMP (dbcAMP) and beta-adrenergic receptor agonist on the production of these cytokines. 2. Type IV PDE inhibitors were more effective at inhibiting the production of TNF-alpha and IL-1 beta by LPS-stimulated PBMC than a nonselective, type III or type III/IV inhibitor. In contrast, these agents had no effect on IL-8 production. 3. Increasing concentrations of dbcAMP progressively reduced the production of TNF-alpha and IL-1 beta but not IL-8. 4. The addition of beta-agonist increased the inhibitory effect of PDE inhibitors tested on the production of TNF-alpha and IL-1 beta. 5. Type IV PDE inhibitors could be potent pharmacological agents for the treatment of diseases in which TNF-alpha and IL-1 beta are important etiological factors.
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PMID:Effects of cAMP-phosphodiesterase isozyme inhibitor on cytokine production by lipopolysaccharide-stimulated human peripheral blood mononuclear cells. 935 14

Human neutrophils, pre-exposed to low concentrations (1-10 ng/ml) of bacterial LPS in the presence of 1% autologous serum, released elastase activity in response to N-formyl-met-leu-phe (fMLP). Both cell incubation with LPS without subsequent fMLP stimulus and fMLP stimulation without prior exposure to LPS failed to promote significant elastase release. Therefore, LPS primes neutrophils for the subsequent release of elastase in response to fMLP. Compared with fMLP, human recombinant C5a had a slight although not significant activity, whereas other chemoattractants such as IL-8, platelet-activating factor and leukotriene B4 were ineffective. The fMLP-induced response of LPS-primed neutrophils was susceptible to suppression by the methane-sulphonanilide anti-inflammatory drug nimesulide and RO 20-1724, which selectively inhibit cAMP-catabolizing phosphodiesterase type IV. This suggests that the elastase release by LPS-primed neutrophils is likely to be controlled by intracellular cAMP, and raises the possibility of limiting pharmacologically the elastase-mediated tissue injury during neutrophilic inflammation.
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PMID:Chemoattractant-induced release of elastase by lipopolysaccharide (LPS)-primed neutrophils; inhibitory effect of the anti-inflammatory drug nimesulide. 935 61

The effects of prostaglandin (PG) I1 analog, SM-10906 (SM-6) and PGE1 on extracellular matrix formation and the release of cytokines by cultured normal human dermal fibroblasts (NDF) and hypertrophic scar fibroblasts (HSF) were compared in order to evaluate the clinical efficacy of PGs in preventing scar formation. In the present study, we measured type I collagen synthesis, collagenase activity, production of interleukin (IL)-6, IL-8, and transforming growth factor (TGF)-beta 1 and levels of adenosine 3,5-cyclic monophosphate (cAMP) in NDF and HSF cultured with or without PGs. The results demonstrated that HSF culture supernatants has a significantly higher level of type I collagen and TGF-beta 1 than those of NDF. However, the levels of collagenase activity and IL-8 in HSF were significantly lower in comparison to that of NDF. There was no substantial difference in IL-6 production between two types of culture cells. On the other hand, PGE1 and SM-6 significantly enhanced collagenase activity and raised the collagenase/type I collagen ratio in the HSF supernatants. In addition, both PGE1 and SM-6 increased production of TGF-beta 1, IL-8 and IL-6 and levels of cAMP in both cell types. However, they had no effect on the type I collagen synthesis of either types. These results suggest that, the stable PGI1 analog, SM-6, similarly acts as PGE1 in HSF by increasing the activity of collagenase.
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PMID:The mode of action of prostaglandin (PG) I1 analog, SM-10906, on fibroblasts of hypertrophic scars is similar to PGE1 in its potential role of preventing scar formation. 941 20

Interleukin-8 (IL-8) receptor A (CXCR1) couples to a pertussis toxin-sensitive G protein to mediate phospholipase Cbeta (PLCbeta) activation and cellular responses. Responses to CXCR1 are attenuated by prior exposure of neutrophils to either IL-8, a cleavage product of the fifth component of complement (C5a) or n-formylated peptides (formylmethionylleucylphenylalanine, fMLP). To characterize the role of receptor phosphorylation in the regulation of the CXCR1, a phosphorylation-deficient mutant, M2CXCR1, was constructed. This receptor, stably expressed in RBL-2H3 cells, coupled more efficiently to G protein and stimulated enhanced phosphoinositide hydrolysis, cAMP production, exocytosis, and phospholipase D activation, and was resistant to IL-8-induced receptor internalization. The rate and total amount of ligand stimulated actin polymerization remained unchanged, but interestingly, chemotaxis was decreased by approximately 30% compared with the wild type receptor. To study the role of receptor phosphorylation in cross-desensitization of chemoattractant receptors, M2CXCR1 was coexpressed with cDNAs encoding receptors for either fMLP (FR), C5a (C5aR), or platelet-activating factor (PAFR). Both C5aR and PAFR were cross-phosphorylated upon M2CXCR1 activation, resulting in attenuated guanosine 5'-3'-O-(thio)triphosphate (GTPgammaS) binding in membranes. In contrast, FR and M2CXCR1 were resistant to cross-phosphorylation and cross-inhibition of GTPgammaS binding by other receptors. Despite the resistance of M2CXCR1 to cross-phosphorylation and receptor/G protein uncoupling, its susceptibility to cross-desensitization of its Ca2+ response by fMLP and C5a, was equivalent to CXCR1. Regardless of the enhancement in certain receptor functions in M2CXCR1 compared with the wild type CXCR1, the mutated receptors mediated equivalent PLCbeta3 phosphorylation and cross-desensitization of Ca2+ mobilization by FR, C5aR, and PAFR. The results herein indicate that phosphorylation of CXCR1 regulates some, but not all of the receptors functions. While receptor phosphorylation inhibits G protein turnover, PLC activation, Ca2+ mobilization and secretion, it is required for normal chemotaxis and receptor internalization. Since phosphorylation of CXCR1 had no effect on its ability to induce phosphorylation of PLCbeta3 or to mediate class-desensitization, these activities may be mediated by independently regulated pathways.
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PMID:Multiple signaling pathways of human interleukin-8 receptor A. Independent regulation by phosphorylation. 955 32

Interleukin-8 (IL-8) and growth-related oncogene protein-alpha (GRO-alpha) belong to a family of alpha chemokines. The biologic effects of IL-8 are realized by binding to two seven-transmembrane receptors R1 and R2 and that of GRO-alpha by binding to receptor R2. Chinese hamster ovary (CHO) cells stably expressing R1 and R2 have been used to demonstrate that the ligand-dependent signaling by both receptors is via the inhibition of adenylyl cyclase. This inhibition is pertussis toxin sensitive and could be mediated by G(alpha)i2, which is present in CHO cells. GRO-alpha inhibits adenylyl cyclase exclusively in CHO-R2 cells, and IL-8 inhibits in both CHO-R1 and CHO-R2 cells. The cAMP status in cells is an easy, reliable, quantifiable signal that is amenable to high throughput screening for small molecule analogs.
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PMID:Inhibition of adenylyl cyclase by alpha chemokines IL-8 and GRO-alpha in Chinese hamster ovary cells expressing R1 and R2 receptors. 956 25

In vivo, vascular walls are exposed to mechanical stretch, which may promote atherogenesis. This study was designed to investigate the effect of mechanical stretch on the production and gene expression of cytokines in endothelial cells (ECs) of human umbilical veins. ECs were cultured on flexible silicone membranes and exposed to cyclic mechanical stretch. Although the secretion levels of interleukin (IL)-1beta, tumor necrosis factor-alpha, IL-6, granulocyte (G) -colony stimulating factor (CSF), G and macrophage (M) -CSF, and M-CSF were not affected by cyclic stretch over 24 hours, the levels of IL-8 and monocyte chemotactic and activating factor (MCAF)/monocyte chemoattractant protein-1 (MCP-1) were significantly increased by cyclic stretch. Northern blot analysis indicated that the mRNA levels of IL-8 and MCAF/MCP-1 were upregulated by cyclic stretch as a function of its intensity. Cytochalasin D, which disrupts the actin cytoskeleton, abolished the stretch-induced gene expression of IL-8 and MCAF/MCP-1. In contrast, neither inhibition of stretch-activated ion channels nor disruption of microtubules affected the induction of these chemokines by cyclic stretch. Northern blot analysis using enzyme inhibitors showed that phospholipase C, protein kinase C, and tyrosine kinase were involved in the stretch-induced gene expression of IL-8 and MCAF/MCP-1, whereas cAMP- or cGMP-dependent protein kinase was not. In conclusion, cyclic stretch enhanced the secretion and gene expression of IL-8 and MCAF/MCP-1 in a stretch-dependent fashion, and the integrity of the actin cytoskeleton and activities of phospholipase C, protein kinase C, and tyrosine kinase may be essential in the process of stretch-induced gene induction of IL-8 and MCAF/MCP-1.
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PMID:Cyclic stretch upregulates production of interleukin-8 and monocyte chemotactic and activating factor/monocyte chemoattractant protein-1 in human endothelial cells. 963 28

Increased numbers of activated eosinophils in bronchial tissue is a feature of asthma and may, in part, be attributed to the prolonged cytokine-dependent survival of eosinophils within the inflamed microenvironment. Low-dose oral theophylline was previously shown to reduce the number of activated eosinophils within the sub-mucosa following allergen exposure. A number of inhibitory actions of theophylline have been described which relate to eosinophil recruitment and activation, including inhibition of cell migration and release of granule basic proteins. In this study we investigated the ability of theophylline to inhibit the release of preformed GM-CSF and IL-8 from eosinophils in vitro, as these cytokines may serve an autocrine function in eosinophil survival in vivo. Eosinophils rapidly released GM-CSF and IL-8 spontaneously, and release was further enhanced in response to sIgA-coated beads. Theophylline inhibited the stimulated, but not the spontaneous, release of both cytokines. We previously reported the role of protein kinase A in inhibition of arachidonic acid mobilization and LTC4 synthesis. Therefore we speculate that cAMP-dependent activation of protein kinase A following theophylline treatment of eosinophils resulted in inhibition of Raf-1 and MAPK/MAPKK dependent activation of phospholipase A2 and consequently inhibition of degranulation and cytokine release.
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PMID:Theophylline inhibits the release of eosinophil survival cytokines--is Raf-1 the protein kinase A target? 975 86


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