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)

TLR4 plays an important role in atherosclerosis, but little is known about the precise mechanism. Herein, we investigated the role of TLR4/NF-kappaB signaling pathway in monocyte-endothelial adhesion induced by low shear stress and Ox-LDL. We found that low shear stress up-regulated TLR4 expression in endothelial cells, and that ox-LDL exerted an obvious synergistic action as revealed by RT-PCR and Western blotting analysis. Low shear stress also significantly up-regulated IL-8 expression in endothelial cells. Meanwhile, NF-kappaB activity and the adhesion force of monocytes were increased, and there was a synergetic action of ox-LDL. However, following transfection with a functional mutant of TLR4 (C3H/HeJ, TLR4 Dicd) or addition of anti-human TLR4 mAb, IL-8 expression was obviously decreased, NF-kappaB activity in cells remarkably inhibited, and the adhesion force of monocyte significantly reduced. Nevertheless, anti-human TLR2 mAb had no similar effects. These findings suggest that TLR4 may be involved in the early stages of atherosclerosis, associating ox-LDL, inflammation/infection, and low shear stress. Therefore, TLR4 is expected to be a new target for preventing and treating atherosclerosis.
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PMID:Role of Toll-like receptor 4/NF-kappaB pathway in monocyte-endothelial adhesion induced by low shear stress and ox-LDL. 1589 21

Entamoeba histolytica is a human pathogen that may invade the intestinal mucosa, causing amoebic colitis or hepatic abscesses when the trophozoites travel through the portal circulation to the liver. Lipopeptidophosphoglycan (LPPG) is a molecular pattern of E. histolytica recognized by the human immune system. Here we report that LPPG is exposed on the cell surface of E. histolytica trophozoites, and is recognized by the host through toll-like receptor (TLR) 2 and TLR4. Correspondingly, human embryonic kidney (HEK)-293 cells were rendered LPPG responsive through overexpression of TLR2 or TLR4/MD2. Moreover, co-expression of CD14 enhanced LPPG signal transmission through TLR2 and TLR4. The interaction of LPPG with TLR2 and TLR4 resulted in activation of NF-kappaB and release of interleukin (IL)-10, IL-12p40, tumour necrosis factor (TNF)-alpha, and IL-8 from human monocytes. Consistent with these findings, responsiveness of mouse macrophages lacking TLR2 expression (TLR2-/-) or functional TLR4 (TLR4d/d) to E. histolytica LPPG challenge was impaired while double deficient macrophages were unresponsive. In contrast to wild-type control and TLR2-/- animals succumbing to lethal shock syndrome, TLR4d/d mice were resistant to systemic LPPG challenge-induced pathology.
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PMID:The innate immune response to Entamoeba histolytica lipopeptidophosphoglycan is mediated by toll-like receptors 2 and 4. 1591 Apr 21

Endotoxin/lipopolysacccharide (LPS) is a potent inflammatory stimulus, which acts on tumour infiltrating leukocytes by eliciting a wide range of factors promoting invasion and metastasis. Less known is the effect of LPS directly on tumour cells. In this study, we analysed whether tumour cell lines from different origin (melanoma, ovarian carcinoma, neuroblastoma) are responsive to LPS in vitro. Results showed that only melanoma cells significantly up-regulated the production of IL-8 and cell adhesion, when triggered with LPS. These effects were associated with the constitutive expression of TLR-4 mRNA in these cells and the expression on the cell membrane of the complete LPS-binding receptor.
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PMID:Melanoma cell lines are responsive in vitro to lipopolysaccharide and express TLR-4. 1592 7

The heterophil is the major polymorphonuclear cell in birds with a functional capacity akin to that of the mammalian neutrophil. Herein, we demonstrate that heterophils constitutively express TLR1/6/10, TLR2 type 1, TLR2 type 2, TLR3, TLR4, TLR5, and TLR7 mRNA. Furthermore, TLR agonists, including flagellin (from Salmonella typhimurium, FGN), peptidoglycan (from Staphylococcus aureus, PGN), ultra-pure lipopolysaccharide (from Salmonella minnesota, LPS), the synthetic double stranded RNA analog [poly(I:C)], and the guanosine analog, loxoribine (LOX) directly induced both an oxidative burst and a degranulation response. Interestingly, the synthetic bacterial lipoprotein Pam3CSK4 (palmitoyl-3-cysteine-serine-lysine-4, PAM) induced degranulation, but no oxidative burst. The bacterial TLR agonists (PAM, PGN, LPS, and FGN) all induced an up-regulation of expression of mRNA of the pro-inflammatory cytokines IL-1beta, IL-6, and IL-8; whereas both poly(I:C) and LOX induced a down-regulation of these cytokine mRNAs. Stimulation of heterophils with each specific TLR agonist led to a differential increase in the phosphorylation of both p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase 1/2 (ERK 1/2) activation, but not the phosphorylation of c-Jun NH2-terminal kinase (JNK). The broad TLR expression profile in heterophils reflects their principal role as first line effector cells in avian host defense against bacterial, viral, fungal, and parasitic infections. The results demonstrate the differential involvement of TLR-induced signals in the stimulation of transduction pathways that regulate the oxygen-dependent and -independent antimicrobial defense mechanisms of avian heterophils.
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PMID:Expression and function of Toll-like receptors in chicken heterophils. 1593 35

IgA Abs help to maintain homeostasis at mucosal surfaces by promoting defense mechanisms that protect against pathogens while suppressing inflammatory responses to commensal organisms and food Ags. The polymeric Ig receptor (pIgR) mediates transport of IgA across mucosal epithelial cells. We hypothesized that signaling through TLRs may up-regulate pIgR expression by intestinal epithelial cells and thus enhance IgA-mediated homeostasis. To test this hypothesis we treated the HT29 human intestinal epithelial cell line with dsRNA, a ligand for TLR3, or LPS, a ligand for TLR4. Both dsRNA and LPS up-regulated levels of pIgR mRNA and cell surface pIgR protein. By contrast, dsRNA but not LPS up-regulated expression of TLR3 and TLR4 mRNA. However, cell surface expression of both TLR3 and TLR4 was enhanced by treatment of HT29 cells with their respective ligands. Transfection of HT29 cells with wild-type and mutated promoter/enhancer plasmids suggested that TLR3 and TLR4 signal primarily through NF-kappaB to enhance transcription of pIgR mRNA. TLR3 signaling resulted in a more pronounced inflammatory response than did TLR4, as evidenced by up-regulation of the transcription factor IFN regulatory factor-1, chemokines IL-8 and RANTES, and the proinflammatory cytokine TNF. Signaling through LPS/TLR4 appears to up-regulate pIgR expression while minimizing proinflammatory responses, a mechanism that could promote IgA-mediated homeostasis in the presence of commensal Gram-negative bacteria.
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PMID:Regulation of the polymeric Ig receptor by signaling through TLRs 3 and 4: linking innate and adaptive immune responses. 1597 71

Vaccinia virus (VV) has many mechanisms to suppress and modulate the host immune response. The VV protein A52R was previously shown to act as an intracellular inhibitor of nuclear factor kappaB (NFkappaB) signaling by Toll-like receptors (TLRs). Co-immunoprecipitation studies revealed that A52R interacted with both tumor necrosis factor receptor-associated factor 6 (TRAF6) and interleukin-1 receptor-associated kinase 2 (IRAK2). The effect of A52R on signals other than NFkappaB was not determined. Here, we show that A52R does not inhibit TLR-induced p38 or c-Jun amino N-terminal kinase (JNK) mitogen activating protein (MAP) kinase activation. Rather, A52R could drive activation of these kinases. Two lines of evidence suggested that the A52R/TRAF6 interaction was critical for these effects. First, A52R-induced p38 MAP kinase activation was inhibited by overexpression of the TRAF domain of TRAF6, which sequestered A52R and inhibited its interaction with endogenous TRAF6. Second, a truncated version of A52R, which interacted with IRAK2 and not TRAF6, was unable to activate p38. Because interleukin 10 (IL-10) production is strongly p38-dependent, we examined the effect of A52R on IL-10 gene induction. A52R was found to be capable of inducing the IL-10 promoter through a TRAF6-dependent mechanism. Furthermore, A52R enhanced lipopolysaccharide/TLR4-induced IL-10 production, while inhibiting the TLR-induced NFkappaB-dependent genes IL-8 and RANTES. These results show that although A52R inhibits NFkappaB activation by multiple TLRs it can simultaneously activate MAP kinases. A52R-mediated enhancement of TLR-induced IL-10 may be important to virulence, given the role of IL-10 in immunoregulation.
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PMID:Vaccinia virus protein A52R activates p38 mitogen-activated protein kinase and potentiates lipopolysaccharide-induced interleukin-10. 1599 38

Alveolar macrophages (AM) are critical components of lung innate immunity and contribute to an effective host response to Pneumocystis pneumonia. Recognition of unopsonized Pneumocystis organisms by human AM is mediated predominantly via mannose receptors and results in phagocytosis, release of reactive oxygen species, and activation of the nuclear transcription factor (NF)-kappaB. However, the AM host defense genes activated by Pneumocystis have not been defined. In the present study, incubation of AM with unopsonized Pneumocystis organisms was not associated with release of interleukin (IL)-1beta, IL-6, or tumor necrosis factor (TNF)-alpha (important cytokines in the host response to Pneumocystis) and did not induce IL-1beta, IL-6, or TNF-alpha mRNA transcripts. These findings were not attributed to Pneumocystis-induced cytopathic changes, as these same AM released IL-8 and matrix metalloproteinase-9 in response to Pneumocystis. NF-kappaB-mediated IL-8 release was independent of Pneumocystis phagocytosis. The observed response was specific, as IL-1beta, IL-6, and TNF-alpha release and mRNA induction were preserved in response to lipopolysaccharide or serum-opsonized Pneumocystis. The absence of IL-1beta, IL-6, and TNF-alpha release in response to Pneumocystis was predominately influenced by AM mannose receptors, as blocking mannose receptors or targeted mannose receptor small interfering RNA functional gene silencing resulted in TNF-alpha release in response to unopsonized Pneumocystis organisms. Furthermore, ligation of AM mannose receptors by unopsonized Pneumocystis organisms reduced Toll-like receptor 4-mediated TNF-alpha release. Taken together, these data suggest that mannose receptors on human AM may suppress select proinflammatory cytokine release and may serve to regulate the innate inflammatory responses to infectious challenge in the lungs.
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PMID:Negative regulatory role of mannose receptors on human alveolar macrophage proinflammatory cytokine release in vitro. 1600 Mar 87

TLRs are involved in innate cell activation by conserved structures expressed by microorganisms. Human T cells express the mRNA encoding most of TLRs. Therefore, we tested whether some TLR ligands may modulate the function of highly purified human CD4+ T lymphocytes. We report that, in the absence of APCs, flagellin (a TLR5 ligand) and R-848 (a TLR7/8 ligand) synergized with suboptimal concentrations of TCR-dependent (anti-CD3 mAb) or -independent stimuli (anti-CD2 mAbs or IL-2) to up-regulate proliferation and IFN-gamma, IL-8, and IL-10 but not IL-4 production by human CD4+ T cells. No effect of poly(I:C) and LPS, ligands for TLR3 and TLR4, respectively, was detected. We also observed that CD4+CD45RO+ memory T cell responses to TLR ligands were more potent than those observed with CD4+CD45RA+ naive T cells. Moreover, among the memory T cells, CCR7- effector cells were more sensitive to TLR ligands than CCR7+ central memory cells. These data demonstrate for the first time a direct effect of TLR5 and TLR7/8 ligands on human T cells, and highlight an innate arm in T cell functions. They also suggest that some components from invading microorganisms may directly stimulate effector memory T cells located in tissues by up-regulating cytokine and chemokine production.
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PMID:Direct stimulation of human T cells via TLR5 and TLR7/8: flagellin and R-848 up-regulate proliferation and IFN-gamma production by memory CD4+ T cells. 1603 93

In the human stomach Toll-like receptors (TLRs) expressed by the gastric epithelium interact with Helicobacter pylori and mediate production of proinflammatory cytokines and chemokines during H. pylori infection. This results in chronic active gastritis, the background from which gastric carcinoma arises via the epithelial precursor lesions, intestinal metaplasia and dysplasia. Therefore, the question is arising whether gastric carcinoma cells are also able to interact with H. pylori. In this study, TLR4, TLR5 and TLR9 expression was investigated on tumor cells of gastric carcinoma and on its precursor lesions, intestinal metaplasia and dysplasia, by immunohistochemistry. Gastric epithelium with intestinal metaplasia (n=10) and dysplasia (n=3) expressed TLR4 and TLR5. TLR4 was strongly expressed by tumor cells of 17 out of 22 and TLR5 by tumor cells of all 22 patients with gastric carcinoma. TLR9, however, was not detectable in intestinal metaplasia or dysplasia and only focally in 6 out of 22 gastric carcinomas. In contrast to H. pylori gastritis, epithelial TLR expression in intestinal metaplasia, dysplasia and gastric carcinoma was diffusely distributed without subcellular polarization as demonstrated by confocal microscopy. This is the first study describing TLR expression on tumor cells of gastric carcinoma and its precursor lesions. Expression of TLRs enables gastric carcinoma cells to interact with H. pylori. As H. pylori can induce gastric carcinoma-promoting factors, such as IL-8, via epithelial TLR expression, TLR expression by gastric carcinoma cells may have a dangerous potential.
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PMID:Toll-like receptors TLR4, TLR5 and TLR9 on gastric carcinoma cells: an implication for interaction with Helicobacter pylori. 1604 57

Peripheral monocytosis may affect the development of heart failure (HF) after acute myocardial infarction (AMI). Activated toll-like receptor (TLR) 4 in monocytes plays an important role in the synthesis of proinflammatory cytokines. We examined TLR4 expression in monocytes, which may be a possible source of proinflammatory cytokines in AMI. Sixty-five patients with AMI and 20 healthy subjects (HS) were studied. Monocytes were isolated from peripheral blood on days 1 and 14 after the onset of AMI. TLR4 levels in monocytes were measured using real-time RT-PCR and flow cytometry. Generation capacity was evaluated by TLR4 levels and cytokine concentrations in the culture medium with lipopolysaccharide (LPS) stimulation. On day 1 after onset, baseline levels of TLR4 and plasma proinflammatory cytokines, notably IL-6 and TNF-alpha, were higher in AMI patients than in HS. These levels remained elevated in AMI patients 14 days after onset. Generation capacities of TLR4 and proinflammatory cytokines (IL-2, IL-6, IL-8, IL-10, GM-CSF and TNF-alpha) were increased in AMI patients compared to HS. LPS-stimulated TLR4 levels were positively correlated with IL-6 and TNF-alpha levels in AMI patients. Baseline TLR4 levels and plasma proinflammatory cytokine (IL-6, GM-CSF and TNF-alpha) levels were higher in AMI patients with HF (n = 22) than in those without HF. Generation capacities of TLR4 and proinflammatory cytokines (IL-6, GM-CSF and TNF-alpha) were greater in AMI patients with HF than in those without HF. Activation of TLR4 through a myocytic inflammatory reaction is associated with HF after AMI. These observations suggest that TLR4 signaling in monocytes may play a role in the development of HF after AMI.
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PMID:Activated toll-like receptor 4 in monocytes is associated with heart failure after acute myocardial infarction. 1605 84


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