Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0243026 (sepsis)
 52,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Toll-like receptors (TLRs) are a recently described family of immune receptors involved in the recognition of pathogen-associated molecular patterns (PAMPs). The central role of TLR-2 and TLR-4 in microbial responses suggests they may be implicated in the pathogenesis of human sepsis. We hypothesized that the incidence and outcome of sepsis would be influenced by the expression of TLR-2 and TLR-4 on monocytes. We have examined the expression of TLR-2 and TLR-4 mRNA and protein and their response to pro- and anti-inflammatory agents on monocytes from subjects in the intensive therapy unit (ITU) with and without Gram-negative, Gram-positive or polymicrobial sepsis. We compared these data to ITU and healthy control subjects. TLR-2 mRNA was significantly up-regulated on monocytes from subjects with both Gram-positive and Gram-negative sepsis. Similarly, we detected increased levels of TLR-2 protein on the surface of monocytes from sepsis subjects relative to ITU controls. TLR-4 mRNA was increased in Gram-positive subjects; however, there was no corresponding increase in TLR-4 protein. Although TLR-4 mRNA expression in healthy control monocytes could be modulated in vitro by culture with lipopolysaccharide or interleukin-10, this was not observed in monocytes obtained from sepsis and ITU control subjects, suggesting that septic and ITU control milieus may alter the immunoregulation of TLR-4 mRNA expression on monocytes. TLR-2 mRNA was not modulated in culture by any stimulus in any group. We suggest that expression and regulatory response of monocyte TLR-2, and to a lesser extent TLR-4 may be abnormal in human sepsis.
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PMID:Differential expression of Toll-like receptor (TLR)-2 and TLR-4 on monocytes in human sepsis. 1508 96

Toll-like receptors (TLRs) are key elements in the innate immune response, functioning as pattern-recognition receptors for the detection and response to endotoxins and other microbial ligands. Inflammatory cytokines play an important role in the activation of the hypothalamic-pituitary-adrenal HPA axis during inflammation and sepsis. The newly recognized major role of TLR2 and TLR4 and the adrenal stress response during critical illnesses such as inflammation and sepsis demand comprehensive analysis of their interactions. Therefore, we analyzed TLR2 and TLR4 expression in human adrenal glands. Western blot analysis demonstrated the expression of TLR2 and TLR4 in the human adrenocortical cell line NCI-H295. Immunohistochemical analysis of normal human adrenal glands revealed TLR2 and TLR4 expression in the adrenal cortex, but not in the adrenal medulla. Considering the crucial role of the HPA axis and the innate immune response during acute sepsis or septic shock, elucidating the functional interaction of these systems should be of great clinical relevance.
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PMID:Toll-like receptor 2 and Toll-like receptor 4 expression in human adrenals. 1530 30

In this paper, we show that plasma from patients with severe sepsis and septic shock but not normal plasma supports lipopolysaccharide (LPS) activation of epithelial cells expressing Toll-like receptor 4 (TLR4). Recombinant soluble myeloid differentiation protein-2 (MD-2) complemented normal plasma and allowed LPS activation of epithelial cells to levels measured with "septic" plasma, whereas soluble MD-2-depleted plasma lost its effects. The same "MD-2 activity" was found in urine from a patient with septic shock and in lung edema fluids from patients with adult respiratory distress syndrome (ARDS). Recombinant soluble MD-2 enabled LPS-dependent activation of epithelial cells bearing TLR4. LPS-binding protein (LBP) and soluble CD14 increased the sensitivity of TLR4-expressing epithelial cells to LPS but were not able to mediate LPS activation of these cells in the absence of soluble MD-2. An anti-MD-2 monoclonal antibody blocked LPS activation of TLR4-expressing cells only in the presence of septic plasma or septic urine. These results suggest that septic plasma containing soluble MD-2 leaking into the extravascular space supports LPS activation of TLR4-expressing epithelial cells. We therefore propose that soluble MD-2 is an important mediator of organ inflammation during sepsis.
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PMID:Soluble MD-2 activity in plasma from patients with severe sepsis and septic shock. 1532 61

Gram-negative sepsis is the major cause of deaths in intensive care units of hospitals and continues to increase worldwide due to the increased frequency of invasive procedures and therapy leading to immunosuppression. This syndrome is characterized by endothelial damage, coagulopathy, loss of vascular tone, tissue hypoperfusion, and multiple-organ failure. They are caused by uncontrolled, overwhelming inflammatory responses, which are triggered by microbial products. Amongst these products, endotoxin also called LPS (lipopolysaccharide), a constituent of the outer membrane of Gram-negative bacteria, is known to play a central role by eliciting immune responses leading to production of proinflammatory cytokines. Our understanding of LPS recognition has increased dramatically over the last several years by identification of Toll-like receptor 4 (TLR4) and MD-2 as LPS recognition molecules. TLR4 is a mammalian homologue of drosophila Toll. The extracellular domain of TLR4 is associated with a molecule called MD-2. Mice lacking either TLR4 or MD-2 do not respond to LPS and are resistant to endotoxin shock. Here, the potential for TLR4-MD-2 as target molecules for therapeutic intervention is discussed.
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PMID:Endotoxin recognition molecules MD-2 and toll-like receptor 4 as potential targets for therapeutic intervention of endotoxin shock. 1537 97

Lipopolysaccharide (LPS) causes a systemic reaction known as sepsis, which is frequently associated with cholestasis. Many biological effects produced by LPS are thought to be mediated by Toll-like receptor 4 (TLR4). Organic anion-transporting polypeptide 4 (Oatp4; Slc21a10) mediates hepatic uptake of bile acids and other organic anions. The purpose of this study was to determine 1) whether LPS decreases Oatp4 mRNA levels; 2) the role of TLR4 in the LPS-induced down-regulation of Oatp4; and 3) the time course of serum concentrations of tumor necrosis factor alpha, interleukin (IL) 1beta, and IL-6 after LPS administration. For the dose-response study, LPS (1 mg/kg i.p.) produced a significant decrease in Oatp4 mRNA levels in TLR4-normal C3H/OuJ mice, and higher doses produced slightly greater decreases. However, none of the doses of LPS examined significantly decreased Oatp4 mRNA levels in TLR4-mutant C3H/HeJ mice. For the time-response study, LPS (5 mg/kg i.p.) produced a rapid decrease in Oatp4 mRNA levels in TLR4-normal C3H/OuJ mice. The maximal decrease in Oatp4 mRNA levels (80%) was observed 12 h after LPS administration and returned to control levels thereafter. In contrast, LPS did not produce a significant decrease in Oatp4 mRNA levels at any time in TLR4-mutant C3H/HeJ mice. These findings demonstrate that LPS decreases Oatp4 mRNA levels in mice, and the decrease is mediated through TLR4.
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PMID:Down-regulation of mouse organic anion-transporting polypeptide 4 (Oatp4; Oatp1b2; Slc21a10) mRNA by lipopolysaccharide through the toll-like receptor 4 (TLR4). 1548 94

The reduced responsiveness of monocytes or granulocytes toward endotoxin (endotoxin tolerance) during sepsis may depend on Toll-like receptors (TLR). The expression of TLR-2 and TLR-4 was measured on neutrophils (PMN) and monocytes from patients with sepsis (n = 21) or healthy controls (n = 12). Leukocytes (1 x 10/mL) were incubated at 37 degrees C with or without a TLR-4 (LPS 1 microg/mL) or a TLR-2 ligand (MALP-2 2 nM). Surface expression of TLR-2 and TLR-4 at 0, 4, and 16 h was determined in FACS after staining with specific antibodies. The release of IL-8 and TNF-alpha was measured by ELISA. Freshly isolated PMN from patients with sepsis exhibited significantly (P < 0.05) higher mean fluorescence for TLR-2 (78.0 +/- 18.6) and TLR-4 (11.4 +/- 2.3) than controls (12.8 +/- 2.2 and 2.3 +/- 0.4). Similarly, monocytes from patients exhibited higher TLR-2 and TLR-4 expression (300.8 +/- 40.6 and 92.7 +/- 12.1) than cells from controls (149.5 +/- 27.1 and 52.2 +/- 7.6). In patients with sepsis, expression of TLR-2 and TLR-4 on PMN increased during 16 h of incubation (106.2 +/- 22.1 and 34.5 +/- 5.3), whereas it remained unchanged in controls (19.3 +/- 6.1 and 5.4 +/- 1.9). Incubation with LPS or MALP-2 had no effect on TLR-4 or TLR-2 expression in cells from either controls or patients. Despite increased TLR expression in cells from patients with sepsis, the endotoxin-induced release of TNF-alpha and IL-8 was indistinguishable from that in controls. Therefore, the endotoxin tolerance seen in patients with sepsis does not depend solely on TLR-2 or TLR-4 expression, and other mechanisms must be involved.
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PMID:Increased expression of toll-like receptor-2 and -4 on leukocytes from patients with sepsis. 1548 31

C57BL/6 and BALB/c mice are prototypical Th1- and Th2-type mouse strains, respectively. In the present study, we attempted to characterize the innate immune response of macrophages from these mouse strains. Macrophages from C57BL/6 mice produced higher levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-12 than those from BALB/c mice after stimulation with macrophage-activating lipopeptide-2 (MALP-2, a synthetic TLR-2 ligand) or lipopolysaccharide (LPS, a TLR-4 ligand). The augmented IL-12 production by C57BL/6 macrophages increased interferon-gamma and, in contrast, decreased IL-13 production by CD4+ T cells. On stimulation with MALP-2 or LPS, C57BL/6 macrophages produced lysosomal enzyme and nitric oxide, effector molecules for bacterial killing, whereas BALB/c macrophages did not. Bactericidal activity of BALB/c macrophages was impaired relative to C57BL/6 macrophages when cells were infected with live bacteria in vitro. In a murine model of septic peritonitis induced by cecal ligation and puncture (CLP), BALB/c mice failed to facilitate bacterial clearance relative to C57BL/6 mice despite an augmented peritoneal leukocyte infiltration that was associated with increased peritoneal levels of cytokines/chemokines. BALB/c mice exhibited increased plasma and hepatic levels of cytokines/chemokines, resulting in an exaggerated systemic inflammation as determined by acute-phase proteins. Finally, BALB/c mice were vulnerable to CLP-induced lethality relative to C57BL/6 mice. Altogether, innate immune response of macrophages is different between these mouse strains, which may affect the development of Th1 and Th2 adaptive immunity in these strains. Reduced systemic inflammatory response in C57BL/6 mice that may result from an eminent local response appears to be beneficial during sepsis.
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PMID:Innate immune response in Th1- and Th2-dominant mouse strains. 1548 39

TLR4 (Toll-like receptor 4) is essential for sensing the endotoxin of Gram-negative bacteria. Mutations or deletion of the TLR4 gene in humans or mice have been associated with altered predisposition to or outcome of Gram-negative sepsis. In the present work, we studied the expression and regulation of the Tlr4 gene of mouse. In vivo, TLR4 levels were higher in macrophages compared with B, T or natural killer cells. High basal TLR4 promoter activity was observed in RAW 264.7, J774 and P388D1 macrophages transfected with a TLR4 promoter reporter vector. Analysis of truncated and mutated promoter constructs identified several positive [two Ets (E twenty-six) and one AP-1 (activator protein-1) sites] and negative (a GATA-like site and an octamer site) regulatory elements within 350 bp upstream of the transcriptional start site. The myeloid and B-cell-specific transcription factor PU.1 bound to the proximal Ets site. In contrast, none among PU.1, Ets-1, Ets-2 and Elk-1, but possibly one member of the ESE (epithelium-specific Ets) subfamily of Ets transcription factors, bound to the distal Ets site, which was indispensable for Tlr4 gene transcription. Endotoxin did not affect macrophage TLR4 promoter activity, but it decreased TLR4 steady-state mRNA levels by increasing the turnover of TLR4 transcripts. TLR4 expression was modestly altered by other pro- and anti-inflammatory stimuli, except for PMA plus ionomycin which strongly increased promoter activity and TLR4 mRNA levels. The mouse and human TLR4 genes were highly conserved. Yet, notable differences exist with respect to the elements implicated in gene regulation, which may account for species differences in terms of tissue expression and modulation by microbial and inflammatory stimuli.
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PMID:Critical role for Ets, AP-1 and GATA-like transcription factors in regulating mouse Toll-like receptor 4 (Tlr4) gene expression. 1553 84

Toll-like receptor 4 (TLR-4) is required for detection of Gram negative bacterial infections by binding lipopolysaccharide (LPS) and for the initiation of inflammatory signaling. Recent studies have demonstrated that a nonsynonymous single-nucleotide polymorphism (Asp299Gly, A+896G) is associated with decreased endotoxin responsiveness and poor outcomes from sepsis. We show that human carriers of this polymorphism show no deficit in LPS induced peripheral blood mononuclear cell (PBMC) mitogen-activated protein kinase (MAPK) activity, no reduction in sensitivity to endotoxin, and variable differences in whole-blood inflammatory cytokine production. These results indicate that this mutation is not a primary determinant of human endotoxin sensitivity.
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PMID:The TLR4 +896 polymorphism is not associated with lipopolysaccharide hypo-responsiveness in leukocytes. 1556 73

Polymorphonuclear neutrophils (PMNs) are essential in initiation and execution of the acute inflammatory response and subsequent resolution of fungal infection. PMNs, however, may act as double-edged swords, as the excessive release of oxidants and proteases may be responsible for injury to organs and fungal sepsis. To identify regulatory mechanisms that may balance PMN-dependent protection and immunopathology in fungal infections, the involvement of different TLR-activation pathways was evaluated on human PMNs exposed to the fungus Aspergillus fumigatus. Recognition of Aspergillus and activation of PMNs occurred through the involvement of distinct members of the TLR family, each likely activating specialized antifungal effector functions. By affecting the balance between fungicidal oxidative and nonoxidative mechanisms, pro- and anti-inflammatory cytokine production, and apoptosis vs necrosis, the different TLRs ultimately impacted on the quality of microbicidal activity and inflammatory pathology. Signaling through TLR2 promoted the fungicidal activity of PMNs through oxidative pathways involving extracellular release of gelatinases and proinflammatory cytokines while TLR4 favored the oxidative pathways through the participation of azurophil, myeloperoxidase-positive, granules and IL-10. This translated in vivo in the occurrence of different patterns of fungal clearance and inflammatory pathology. Both pathways were variably affected by signaling through TLR3, TLR5, TLR6, TLR7, TLR8, and TLR9. The ability of selected individual TLRs to restore antifungal functions in defective PMNs suggests that the coordinated outputs of activation of multiple TLRs may contribute to PMN function in aspergillosis.
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PMID:TLRs govern neutrophil activity in aspergillosis. 1558 66


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