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Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study explored the relationship between cytokines (TNF, IL-1, IL-6), coagulation and fibrinolytic factors in the early stage of sepsis syndrome and the relation between these factors with the severity of inflammatory illness as measured by the Simplified Acute Physiology Score (SAPS). Twenty-one normal controls were compared to 34 patients divided into three categories ranging from uncomplicated postoperative patients, to patients with severe infectious conditions including septic shock. A major hemostatic imbalance was demonstrated with particularly marked reduction in fibrinolytic activity [drop of antithrombin III (ATIII) and protein C with an increase of plasminogen activator inhibitor (PAI-1) levels] which were directly correlated with the severity of the inflammatory state. Both ATIII and PAI-1 levels were correlated with the levels of TNF and IL-6 and the severity of illness as measured by SAPS. We established an index, ATIII/PAI-1 antigen that is significantly different among the four groups (p < 0.001) and strongly correlated with the SAPS (p < 0.001). As PAI-1 could be secreted not only by TNF activating endothelial cells but also by hepatocytes activated by insulinemia, treatment of sepsis with cytokine-specific agents might be of limited effect.
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PMID:Coagulation/fibrinolysis balance in septic shock related to cytokines and clinical state. 795 54

Sepsis is the most important cause of mortality in the Intensive Care Units. At present, sepsis is understood to be the inflammatory response of the host to infection, rather than a direct effect of microbial aggression. From the clinical standpoint, this inflammatory response is known as systemic inflammatory response syndrome (SIRS). Pathophysiologically, SIRS is characterized by the activation of several groups of cell (monocytes/macrophages, PMNs, and endothelial cells) and by the release of inflammatory mediators (cytokines and others). Tumor necrosis factor (TNF) is the first cytokine released by endotoxin action over monocyte/macrophage. TNF secretion, modulated by interferon gamma (IFN gamma) and interleukin 10 (IL-10), is followed by release of other cytokines such as interleukins (IL) (IL-1, IL-6 and IL-8). These mediators are able to act over hemostasis activating the extrinsic pathway through tissue factor expression. The action of the mediators over endothelial cells induces an increase in plasminogen activator inhibitor type 1 (PAI-1) levels with inhibition of fibrinolysis. Both coagulation activation and fibrinolysis blockade result in fibrin deposit in the microvascular system. The complexity of the mechanisms implicated in systemic inflammatory response make a general rule so difficult to establish, because patient response is highly individualized and it is not possible to know which moment of this dynamic process is being analyzed.
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PMID:Inflammatory mediators and their influence on haemostasis. 795 61

Mild infection or sublethal dose of endotoxin elicits a brief elevation of GH and PRL in the serum. These hormones have proinflammatory and immunostimulatory effect. In severe trauma, sepsis and shock, GH and PRL are suppressed, whereas glucocorticoids and catecholamines are elevated. Under these conditions an acute phase response is initiated by tissue derived (cytokine) hormones, namely IL-1, IL-6, TNF alpha, and several others, which elicit a neuroendocrine response and initiate major metabolic alterations. There is fever and catabolism prevails, whereas the synthesis of acute phase proteins in the liver, cell proliferation in the bone marrow, and protein synthesis by leukocytes is elevated. This is an emergency reaction to save the organism after the local immune/inflammatory response has failed to contain and eliminate the infectious agent. During sepsis and endotoxin shock the systemic activation of the complement system and of leukocytes releasing enzymes and highly toxic cytokines seriously threaten survival. Glucocorticoids suppress proinflammatory cytokine production and potentiate the secretion of acute phase proteins. Some of these proteins, such as C reactive protein, or LPS binding protein, are designed to combine with microorganisms and trigger their destruction by the activation of complement system and of phagocytes. The increased production of some complement components also helps host resistance. The rise in serum fibrinogen promotes blood clotting which can serve to isolate the invading agent by triggering thrombosis in infected tissues. A number of enzyme inhibitors are produced as acute phase proteins, which are likely to serve to curb the nonspecific damage inflicted by enzymes released from activated phagocytes and from damaged cells into the circulation during sepsis and shock. Catecholamines are also elevated, which serve to inhibit inflammatory responses and to promote, even initiate, the acute phase response. If the acute phase reaction fails to protect the host, shock will develop. Patients with subclinical adrenal insufficiency succumb to septic shock almost invariably if glucocorticoid therapy is not given. However, glucocorticoid treatment of septic patients with normal adrenal function has not been helpful. The use of antibiotics to control infection did not lead to spectacular success either because of the emergence of resistant bacterial strains or the enhanced release of endotoxin by this therapy. The new approaches to prevent and treat septic shock involve the use of antibodies capable of neutralizing LPS and of cytokines and the inhibition of cytokine action by antagonist agents.
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PMID:Neuroendocrine defence in endotoxin shock (a review). 797 6

Two types of cellular IL-1Rs have been characterized and cloned from both human and murine sources. The type II IL-1R has a very short cytoplasmic domain and does not seem to participate in IL-1 signaling. We demonstrate that type II IL-1Rs are released from the surface of neutrophils in response to treatment with TNF or endotoxin. In addition, serum from patients with sepsis syndrome contains elevated levels of soluble type II IL-1Rs. Neutrophils isolated from patients with sepsis have greatly enhanced expression of type II IL-1R mRNA and cell surface receptors and are therefore a likely source for the shed receptors in serum. Of the three forms of IL-1, soluble type II IL-1R binds IL-1 beta with highest affinity and also selectively inhibits IL-1 beta activity. We propose that increased cell surface expression and rapid release of preformed type II IL-1R from neutrophils, as a soluble IL-1 beta binding protein, represents a mechanism that has evolved for regulating IL-1 activity in sepsis.
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PMID:Elevated levels of shed type II IL-1 receptor in sepsis. Potential role for type II receptor in regulation of IL-1 responses. 798 76

The gastrointestinal tract, besides being the organ responsible for nutrient absorption, is also a metabolic and immunological system, functioning as an effective barrier against endotoxin and bacteria in the intestinal lumen. The passage of viable bacteria from the gastrointestinal tract through the epithelial mucosa is called bacterial translocation. Equally important may be the passage of bacterial endotoxin through the mucosal barrier. This article reviews the evidence that translocation of both endotoxin and bacteria is of clinical significance. It summarises recent published works indicating that translocation of endotoxin in minute amounts is a physiological important phenomenon to boost the reticuloendothelial system (RES), especially the Kupffer cells, in the liver. Breakdown of both the mucosal barrier and the RES capacity results in systemic endotoxaemia. Systemic endotoxaemia results in organ dysfunction, impairs the mucosal barrier, the clotting system, the immune system, and depresses Kupffer cell function. If natural defence mechanisms such as lipopolysaccharide binding protein, high density lipoprotein, in combination with the RES, do not respond properly, dysfunction of the gut barrier results in bacterial translocation. Extensive work on bacterial translocation has been performed in animal models and occurs notably in haemorrhagic shock, thermal injury, protein malnutrition, endotoxaemia, trauma, and intestinal obstruction. It is difficult to extrapolate these results to humans and its clinical significance is not clear. The available data show that the resultant infection remains important in the development of sepsis, especially in the critically ill patient. Uncontrolled infection is, however, neither necessary nor sufficient to account for the development of multiple organ failure. A more plausible sequelae is that bacterial translocation is a later phenomenon of multiple organ failure, and not its initiator. It is hypothesized that multiple organ failure is more probably triggered by the combination of tissue damage and systemic endotoxaemia. Endotoxaemia, as seen in trauma patients especially during the first 24 hours, in combination with tissue elicits a systemic inflammation, called Schwartzmann reaction. Interferon gamma, a T cell produced cytokine, is thought to play a pivotal part in the pathogenesis of this reaction. This reaction might occur only if the endotoxin induced cytokines like tumour necrosis factor and interleukin 1, act on target cells prepared by interferon gamma. After exposure to interferon gamma target cells become more sensitive to stimuli like endotoxin, thus boosting the inflammatory cycle. Clearly, following this line of reasoning, minor tissue damage or retroperitoneal haematoma combined with systemic endotoxaemia could elicit this reaction. The clinically observed failure of multiple organ systems might thus be explained by the interaction of tissue necrosis and high concentrations of endotoxin because of translocation. Future therapeutic strategies could therefore focus more on binding endotoxin in the gut before the triggering event, for example before major surgery. Such a strategy could be combined with the start of early enteral feeding, which has been shown in animal studies to have a beneficial effect on intestinal mucosal barrier function and in traumatized patients to reduce the incidence of septic complications.
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PMID:Clinical significance of translocation. 812 86

To investigate the pathogenesis of liver dysfunction accompanying intra-abdominal sepsis, we used rats with cecal ligation and punctures (CLP) and examined the expression of the inflammatory cytokines IL-1-alpha, IL-1-beta, and TNF-alpha, as well as the expression of a cell adhesion molecule, ICAM-1, in the liver. We also examined the expression of Ia antigen and interleukin-2 receptor (IL-2R) on hepatic macrophages. Hepatic macrophages isolated from rats 24 hours after CLP exhibited significantly higher IL-1 and TNF activity than those from control rats. Hepatic macrophages isolated from rats 72 hours after CLP exhibited the maximal IL-1 and TNF activity. In the hepatic nonparenchymal cells, IL-1-alpha mRNA was induced 1 hour after CLP, increasing to the maximal level 3 hours after CLP, whereas IL-1-beta mRNA was induced gradually, reaching a peak 6 hours after CLP. ICAM-1 mRNA reached a peak 3 hours after CLP. Induction of TNF-alpha mRNA was not detected by the present Northern blot analysis. Seventy-two hours after CLP, the proportions of hepatic macrophages expressing Ia antigens and IL-2R were increased significantly, as revealed by the flow cytometric analysis. In conclusion, the present study showed that hepatic macrophages are in an activated state in sepsis as indicated by their increased production of inflammatory monokines and their increased expression of immunomodulatory surface molecules. Further, we demonstrated the sequential induction of the mRNA of the various inflammatory cytokines and ICAM-1. These findings strengthen the notion that these cytokines are relevant to the pathogenesis of liver injury associated with sepsis.
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PMID:Immunologic activation of hepatic macrophages in septic rats: a possible mechanism of sepsis-associated liver injury. 813 56

In severe infections two factors play a part: the infectious agent and the response of the host. The response of the host involves production of a large number of endogenous mediators including a number of cytokines that are currently the focus of many studies: tumor necrosis factor (TNF alpha), interleukins (IL-1 and IL-6), and interferon gamma (IGN gamma). These cytokines are part of the body's normal defense mechanisms but can have toxic effects when produced in excessive amounts. Although levels of these cytokines are often high in the blood of patients with sepsis, persistence of these elevations is the main indicator of severe infection. Experimentally, injections of TNF alpha and IL-1 reproduce the manifestations of severe sepsis. Mice that are genetically unable to produce TNF alpha are resistant to the injection of endotoxin. Severe sepsis can be prevented by pretreatment of animals with anticytokine agents (polyclonal and monoclonal antibodies and anti-receptor agents ...). Many issues remain unresolved: for instance, the experimental results obtained with an intravenous bolus of endotoxin or bacteria have not been confirmed in some animal models of subacute infection. These models may more closely resemble human infections. The interrelations between these cytokines are extremely complex. Synergistic effects do occur, but the effects of combinations of cytokines can be different from those of each cytokine given alone... It follows that therapeutic use in humans of anti-cytokine molecules is still an approach of uncertain outcome that will perhaps be clarified by ongoing multicenter clinical trials.
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PMID:[Cytokines and severe infections]. 830 25

Experimental acute pyelonephritis in monkeys led to death in some of the animals following renal E. coli inoculation. It was found that both the inflammatory response and cytokine activation were much more severe in these monkeys as compared with others that survived. IL-1 was decreased just before death, and there were early increases in IL-2 and IL-6 serum concentrations, but no significant increase in TNF values. The data suggest that death in sepsis is due in part to excessive cytokine release because of a decrease in the protective activity of IL-1.
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PMID:Events leading to septic death from experimental acute pyelonephritis in the monkey. 834 80

D factor, also known as leukemia inhibitory factor, is a pleiotropic cytokine whose role during acute injury and inflammation is not known. Intraperitoneal administration of Escherichia coli endotoxin induced D factor gene expression in mice, and passive immunization against D factor protected them from the lethal effects of endotoxin and blocked endotoxin-induced increases in serum levels of interleukin 1 and 6. Peak levels of tumor necrosis factor and interferon gamma were not affected. These results indicate that D factor is an essential early mediator of the inflammatory cytokine response and therefore may be important in the pathogenesis of the many inflammatory conditions, such as sepsis, arthritis, allograft rejection, and cancer immunotherapy.
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PMID:Passive immunization of mice against D factor blocks lethality and cytokine release during endotoxemia. 835 47

IL-1ra is the first described naturally occurring receptor antagonist of any cytokine or hormone-like molecule. IL-1ra is a member of the IL-1 family by three criteria: amino acid sequence homology of 26 to 30% to IL-1 beta and 19% to IL-1 alpha; similarities in gene structure; and common gene localization to human chromosome 2q14. Two structural variants of IL-1ra exist: sIL-1ra, a secretory molecule produced by monocytes, macrophages, neutrophils, fibroblasts, and other cells; and icIL-1ra, an intracellular molecule produced by keratinocytes and other epithelial cells, macrophages, and fibroblasts. IL-1ra production by monocytes, macrophages, and neutrophils may be regulated in a differential fashion with IL-1 beta. Human IL-1ra binds to both human IL-1RIs and IL-1RIIs on cell surfaces, although with 100-fold greater avidity to IL-1RIs. IL-1ra may bind preferentially to soluble IL-1RIs and not at all to soluble IL-1RIIs. IL-1ra competitively inhibits binding of both IL-1 alpha and IL-1 beta to cell surface receptors without inducing any discernible intracellular responses. All three forms of IL-1 may bind to IL-1 receptors in a similar fashion but IL-1ra may lack the secondary interactions necessary to trigger cell responses. A 100-fold or greater excess of IL-1ra over IL-1 may be necessary to inhibit biological responses to IL-1 both in vitro and in vivo. The roles of sIL-1ra and icIL-1ra in normal physiology or in host defense mechanisms remain unclear. The administration of IL-1ra blocks the effects of IL-1 in some animal models of septic shock, inflammatory arthritis, graft-versus-host disease, and inflammatory bowel disease. The preliminary results of clinical trials in humans indicate possible efficacy of IL-1ra in sepsis syndrome, rheumatoid arthritis, and GVHD.
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PMID:Interleukin-1 receptor antagonist. 837 62


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