Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stimulation with lipopolysaccharide (LPS) will lead to the expression of a variety of genes in CD14+ monocytes/macrophages, but also in CD14- fibroblasts and endothelial cells. Upon secondary LPS stimulation, the expression of many of these genes is only minimal. This applies to several cytokines, most prominent among them tumor necrosis factor (TNF). Induction of tolerance appears to require some degree of activation in the primary exposure, as partial structures of LPS induce tolerance, as long as they are able to activate cells. Studies on the mechanism of unresponsiveness in tolerant cells show that the CD14 LPS receptor is not downregulated but may even increase in number at the cell surface. Furthermore, this receptor appears to be functional in that mobilization of the transcription factor NF-kappa B does still occur. This NF-kappa B complex is composed primarily of p50p50 homodimers, that bind to the respective DNA motif in the promoter region of many proinflammatory genes, thereby blocking transactivation. However, LPS tolerance does not lead to downregulation of all kinds of response, as some genes are even increased in expression upon secondary stimulation; these include p50 of NF-kappa B, TNF receptor type II and interleukin-10 (IL-10). These gene products are involved in the downregulation of proinflammatory cytokines and may thereby be instrumental in the unresponsiveness observed. Hence, tolerance to LPS is not a passive process that occurs in an exhausted cell; rather, it is a well-controlled active response that is orchestrated in order to prevent excessive inflammation. Important modulators of tolerance are glucocorticoids, which result in a general decrease of gene expression, and interferon-gamma (IFN-gamma), which enhances expression of proinflammatory genes. LPS tolerance does occur in some clinical settings, as in hemodialysis, in sepsis and in patients treated repeatedly with LPS or other monocyte activators. In fact, LPS tolerance may be exploited for prophylaxis of severe sepsis in patients at risk.
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PMID:Molecular mechanism in tolerance to lipopolysaccharide. 758 50

We studied the effect of PPM-18, a chemically synthesized naphthoquinone derivative and also an anti-inflammatory agent, on the lipopolysaccharide (LPS)-activated inducible NO synthase (iNOS) expression in rat alveolar macrophages. Pretreatment of macrophages with PPM-18 (0.1-10 microM) significantly inhibited nitrite production, iNOS protein expression and iNOS mRNA accumulation. PPM-18 did not directly affect the enzymic activities of iNOS and other constitutive NOS forms. The LPS-induced increase in nuclear transcription factor kappaB (NF-kappaB) p65 and p50 in nucleus was suppressed by PPM-18 (10 microM). Moreover electrophoretic mobility-shift assays demonstrated that PPM-18 inhibited DNA binding to NF-kappaB induced by LPS in whole cells but not when added in the nuclear extract, suggesting that PPM-18 did not interfere directly with the binding of NF-kappaB to DNA and that some events had to be processed before NF-kappaB could bind DNA. Examination of NF-kappaB showed that PPM-18 stabilized the NF-kappaB inhibitor, IkappaBalpha, by preventing its degradation from NF-kappaB. Therefore the stabilization of IkappaBalpha might have contributed to the inhibition of NF-kappaB activation. These results also indicate strongly that NF-kappaB is involved in the production of NO on stimulation by LPS. PPM-18 significantly decreased the production of tumour necrosis factor alpha in response to LPS. PPM-18 protects mice against LPS-induced lethal toxicity. These results also indicate that PPM-18 is a potent inhibitor of iNOS expression by blocking the binding of NF-kappaB to promoter and exerts a beneficial effect in the mouse model of sepsis.
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PMID:Inhibition of nitric oxide synthase expression by PPM-18, a novel anti-inflammatory agent, in vitro and in vivo. 937 89

Recognition of bacterial endotoxin (LPS) elicits multiple host responses, including activation of cells of the innate immune system. LPS exposure occurs repeatedly during septicemia, making strict regulation of gene expression necessary. Such regulation might prevent, for example, the continuous production of proinflammatory cytokines such as tumor necrosis factor (TNF), which could lead to severe vascular collapse. Tolerance to LPS is characterized by a diminished production of TNF during prolonged exposure to LPS, and is therefore likely to represent an essential control mechanism during sepsis. In the present study, which uses mice with genetic deletions of the proteins of NF-kappaB complex, we provide data demonstrating that increased expression of the p50 subunit of NF-kappaB directly results in the downregulation of LPS-induced TNF production. This contention is supported by the following observations: (1) tolerance to LPS is not induced in macrophages from p50-/- mice; (2) long-term pretreatment with LPS does not block synthesis of TNF mRNA in p50-/- macrophages (in contrast to wild-type macrophages); (3) ectopic overexpression of p50 reduces transcriptional activation of the murine TNF promoter; and (4) analysis of the four kappaB sites from the murine TNF promoter demonstrates that binding of p50 homodimers to the positively acting kappaB3 element is associated with development of the LPS-tolerant phenotype. Thus, p50 expression plays a key role in the development of LPS tolerance.
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PMID:Regulation of an essential innate immune response by the p50 subunit of NF-kappaB. 980 78

The expression of NF-kappaB was studied in freshly isolated peripheral blood mononuclear cells (PBMC) of patients with severe sepsis and major trauma. The expression of p65p50 heterodimer, the active form of NF-kappaB, was significantly reduced for all patients as compared with control subjects. The p50p50 homodimer, an inhibitory form of NF-kappaB, was reduced in the survivors of sepsis and in patients with trauma. Subsequent in vitro stimulation of PBMC with lipopolysaccharide (LPS) did not induce further NF-kappaB nuclear translocation: the survivors of sepsis and trauma patients showed low expression of both p65p50 and p50p50, whereas nonsurvivors of sepsis showed a predominance of the inactive homodimer and a low p65p50/p50p50 ratio when compared with control subjects. In the later group of patients there was a reverse correlation between plasma IL-10 levels and the p65p50/p50p50 ratio after in vitro LPS stimulation (r = -0.8, p = 0.04). The reduced expression of nuclear NF-kappaB was not due to its inhibition by IkappaBalpha, as very low expression of IkappaBalpha, as well as low levels of p65 and p50 were found in the cytoplasm of PBMC from patients with sepsis and trauma when compared with control subjects. These results demonstrate that upon LPS activation, PBMC of patients with systemic inflammatory response syndrome show patterns of NF-kappaB expression that resemble those reported during LPS tolerance: global down-regulation of NF-kappaB in survivors of sepsis and trauma patients and the presence of large amounts of the inactive homodimer in the nonsurvivors of sepsis.
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PMID:NF-kappaB expression in mononuclear cells of patients with sepsis resembles that observed in lipopolysaccharide tolerance. 1106 29

Macrophage activation plays a central role in host defense against a variety of pathogens via inducible messengers. The transcription factor NF-kappaB controls the synthesis of cytokines involved in immune responses. In quiescent cells, NF-kappaB is located in the cytosol bound to an inhibitor IkappaB. Upon appropriate signal, NF-KB translocates to the nucleus and binds to DNA. The present study investigated the involvement of an immunomodulator, (diHDA-glycerol) on the NF-kappaB/IkappaB complex. Results were compared to those obtained with lipopolysaccharide (LPS) as a major virulence factor in bacterial sepsis. Data showed that exposure of J774.1 cells either to LPS or diHDA-glycerol substantially increased with time the nuclear levels of NF-kappaB complexes. Antibodies to various NF-kappaB proteins supershifted p50, p65 and to a lesser extent c-rel. Western blot analyses showed a rapid cytosolic IkappaB-alpha turn over following LPS exposure in contrast to diHDA-glycerol treatment. Further experiments investigated the involvement of protein kinase C (PKC) by using two inhibitors, staurosporine and H7. Pretreatment of J774.1 with either inhibitor prior to diHDA-glycerol or LPS exposure decreased NF-kappaB activation. Our results indicate that diHDA-glycerol was acting on NF-kappaB through IkappaB regulative mechanisms differing from those used by LPS. DiHDA-glycerol is likely acting on many other transcription factors targeting distinct genes implied in up regulation of the immune system.
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PMID:Effect of a synthetic lipid immunomodulator on the regulation of the transcription factor NF-kappaB. 1110 79

Human protein C is a natural anticoagulant factor, and a recombinant activated form of the molecule (rhAPC) is completing clinical evaluation for treatment of severe sepsis. Because of the pathophysiologic role of endothelial dysfunction in severe inflammatory disease and sepsis, we explored the possibility that rhAPC might directly modulate endothelial function, independent of its anticoagulant activity. Using broad transcriptional profiling, we show that rhAPC directly modulates patterns of endothelial cell gene expression clustering into anti-inflammatory and cell survival pathways. rhAPC directly suppressed expression of p50 and p52 NFkappaB subunits, resulting in a functional decrease in NFkappaB binding at target sites. Further, rhAPC blocked expression of downstream NFkappaB regulated genes following tumor necrosis factor alpha induction, including dose-dependent suppression of cell adhesion expression and functional binding of intracellular adhesion molecule 1, vascular cell adhesion molecule 1, and E-selectin. Further, rhAPC modulated several genes in the endothelial apoptosis pathway, including the Bcl-2 homologue protein and inhibitor of apoptosis protein. These pathway changes resulted in the ability of rhAPC to inhibit the induction of apoptosis by the potent inducer, staurosporine. This new mechanistic understanding of endothelial regulation and the modulation of tumor necrosis factor-induced endothelial dysfunction creates a novel link between coagulation, inflammation, and cell death and provides insight into the molecular basis for the efficacy of APC in systemic inflammation and sepsis.
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PMID:Gene expression profile of antithrombotic protein c defines new mechanisms modulating inflammation and apoptosis. 1127 52

Endotoxin tolerance, the transient, secondary down-regulation of a subset of endotoxin-driven responses after exposure to bacterial products, is thought to be an adaptive response providing protection from pathological hyperactivation of the innate immune system during bacterial infection. However, although protecting from the development of sepsis, endotoxin tolerance also can lead to fatal blunting of immunological responses to subsequent infections in survivors of septic shock. Despite considerable experimental effort aimed at characterizing the molecular mechanisms responsible for a variety of endotoxin tolerance-related phenomena, no consensus has been achieved yet. IL-12 is a macrophage- and dendritic cell (DC)-derived cytokine that plays a key role in pathological responses to endotoxin as well as in the induction of protective responses to pathogens. It recently has been shown that IL-12 production is suppressed in endotoxin tolerance, providing a likely partial mechanism for the increased risk of secondary infections in sepsis survivors. We examined the development of IL-12 suppression during endotoxin tolerance in mice. Decreased IL-12 production in vivo is clearly multifactorial, involving both loss of CD11c(high) DCs as well as alterations in the responsiveness of macrophages and remaining splenic DCs. We find no demonstrable mechanistic role for B or T lymphocytes, the soluble mediators IL-10, TNF-alpha, IFN-alphabeta, or nitric oxide, or the NF-kappaB family members p50, p52, or RelB.
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PMID:IL-12 suppression during experimental endotoxin tolerance: dendritic cell loss and macrophage hyporesponsiveness. 1139 May 4

Tumor necrosis factor alpha (TNF-alpha) is a critical mediator of myocardial dysfunction during acute inflammatory states. TNF-alpha is also present in the serum of patients with chronic cardiac diseases. In monocytes, TNF-alpha stimulates cells by activating distinct signaling pathways that involve nuclear translocation of NF kappa B. Since NF kappa B may also regulate the expression of genes that could contribute to myocardial dysfunction, the cardiomyocyte NF kappa B activation following acute or chronic TNF-alpha challenges was investigated. To accomplish this, the authors either acutely administered TNF-alpha to healthy mice, or used transgenic mice which chronically overexpress TNF-alpha exclusively in cardiac myocytes. Following acute administration of TNF-alpha, cardiac NF kappa B translocation was detected from 15 min to 2 h post-challenge. The time course of I kappa B alpha degradation was consistent with the kinetics of NF kappa B translocation. I kappa B beta degradation was slower and less dramatic. In transgenic mice chronically overexpressing TNF-alpha, myocardial NF kappa B activation was detected at all ages tested (21, 40, and 75 days). In contrast to acutely challenged animals, two distinct NF kappa B proteins were activated in chronically challenged animals, p50--65 heterodimers as well as p50 homodimers. Activation of both could be transiently blocked by administration of a recombinant chimeric TNF-alpha receptor antagonist (rhTNFR:Fc). I kappa B alpha, but not I kappa B beta, levels were elevated in transgenics when compared to wild-type animals. These data indicate that following acute TNF-alpha administration, which simulates bacterial sepsis, myocardial p50-p65 translocates within minutes. Chronic TNF-alpha exposure, which is thought to occur in long-standing congestive heart failure, results in translocation of transcriptionally inactive p50 homodimers in addition to transcriptionally active p50--65 heterodimers. It is speculated that activation of p50 homodimers constitutes an adaptive response to minimize the inflammatory consequences of chronic cardiac TNF-alpha exposure.
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PMID:Differential regulation of myocardial NF kappa B following acute or chronic TNF-alpha exposure. 1144 28

Tumor necrosis factor-alpha (TNF-alpha), an early inflammatory mediator typically regulated by nuclear factor kappa B (NF-kappa B), plays a critical role in the development of cardiovascular dysfunction in sepsis. While several myocardial cell types synthesize TNF-alpha, the importance of the myocardial endothelium in sepsis-related cardiac cytokine production is unclear. To determine the role of the human coronary artery endothelial cell (HCA-EC) in the cytokine response to endotoxin we measured in vitro TNF-alpha synthesis, TNF-alpha mRNA, and the associated NF-kappa B response to LPS. To determine the magnitude of the HCA-EC response we assessed the TNF-alpha and NF-kappa B response to LPS in a human monocytic cell line (THP-1) as well. We observed an increase in supernatant TNF-alpha from LPS-stimulated HCA-EC (12 h) that was ablated by the proteosome inhibitor, ALLN (N-acetyl-Leu-Leu-norleucinal). Similarly, ALLN-sensitive TNF-alpha was produced by monocytes following LPS, although at concentrations 100-fold higher than HCA-EC. TNF-alpha mRNA from HCA-EC was detected at 60 min in LPS-stimulated cells, but not in unstimulated cells or cells pretreated with ALLN. NF-kappa B p50/p65 subunits were detectable in endothelial nuclear protein 60 min following LPS. In contrast, NF-kappa B subunits from monocytes were detected at 15 min. Also, while ALLN only attenuated endothelial NF-kappa B translocation, monocyte NF-kappa B translocation was completely inhibited. These data suggest endotoxin-stimulated human coronary endothelial cells express TNF-alpha, which is regulated in part by NF-kappa B activation, in a manner and degree distinct from human monocytes.
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PMID:Human coronary endothelial cell activation by endotoxin is characterized by NF-kappa B activation and TNF-alpha synthesis. 1169 72

An imbalance between thrombin and antithrombin III contributed to vascular hyporeactivity in sepsis, which can be attributed to excess NO production by inducible nitric-oxide synthase (iNOS). In view of the importance of the thrombin-activated coagulation pathway and excess NO as the culminating factors in vascular hyporeactivity, this study investigated the effects of thrombin on the induction of iNOS and NO production in macrophages. Thrombin induced iNOS protein in the Raw264.7 cells, which was inhibited by a thrombin inhibitor, LB30057. Thrombin increased NF-kappaB DNA binding, whose band was supershifted with anti-p65 and anti-p50 antibodies. Thrombin elicited the phosphorylation and degradation of I-kappaBalpha prior to the nuclear translocation of p65. The NF-kappaB-mediated iNOS induction was stimulated by the overexpression of activated mutants of Galpha(12/13) (Galpha(12/13)QL). Protein kinase C depletion inhibited I-kappaBalpha degradation, NF-kappaB activation, and iNOS induction by thrombin or the iNOS induction by Galpha(12/13)QL. JNK, p38 kinase, and ERK were all activated by thrombin. JNK inhibition by the stable transfection with a dominant negative mutant of JNK1 (JNK1(-)) completely suppressed the NF-kappaB-mediated iNOS induction by thrombin. Conversely, the inhibition of p38 kinase enhanced the expression of iNOS. In addition, JNK and p38 kinase oppositely controlled the NF-kappaB-mediated iNOS induction by Galpha(12/13)QL. Hence, iNOS induction by thrombin was regulated by the opposed functions of JNK and p38 kinase downstream of Galpha(12/13). In the JNK1(-) cells, thrombin did not increase either the NF-kappaB binding activity or I-kappaBalpha degradation despite I-kappaBalpha phosphorylation. These results demonstrated that thrombin induces iNOS in macrophages via Galpha(12) and Galpha(13), which leads to NF-kappaB activation involving the protein kinase C-dependent phosphorylation of I-kappaBalpha and the JNK-dependent degradation of phosphorylated I-kappaBalpha.
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PMID:Thrombin induces nitric-oxide synthase via Galpha12/13-coupled protein kinase C-dependent I-kappaBalpha phosphorylation and JNK-mediated I-kappaBalpha degradation. 1260 53


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