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

Gram-negative bacteria commonly cause serious infections in hospitalized patients, and those that lead to bacteremic episodes and sepsis syndrome are associated with the highest mortality rate. Sepsis syndrome frequently progresses to multisystem organ dysfunction and failure, with as many as 400,000 cases occurring annually. Unfortunately, the associated mortality rate remains about 40%. Lipopolysaccharide (LPS, endotoxin), an integral component of the gram-negative bacterial outer membrane, plays a critical role in the pathophysiology of this lethal disease process. It is capable of interacting with host macrophages, a process that leads to the secretion of an increasingly well-characterized array of macrophage cytokines. Several different classes of compounds that bind directly to LPS and thereby neutralize its effects are being examined. These consist of anti-LPS monoclonal antibodies (mAbs), naturally occurring proteins and their derivatives (e.g., bactericidal/permeability-increasing protein [BPI], Limulus anti-LPS factor [LALF]), and certain antibiotics (polymyxin B, taurolidine). The molecular biology of BPI, LALF, and LPS binding protein (LBP, which augments the host response to LPS) is of considerable interest, as each demonstrates considerable genetic sequence homology. Although two anti-LPS monoclonal antibodies (HA-1A, E5) did not demonstrate efficacy during sepsis syndrome, information obtained from these clinical trials provided investigators with the ability to better understand this disease process. However, a detailed understanding of the biology of endotoxin antagonism is beginning to emerge, and the application of this knowledge in the clinical setting provides hope that it may be possible to reduce the mortality of sepsis syndrome caused by these microorganisms to a statistic well below the current 40%.
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PMID:Prevention and treatment of multiple organ dysfunction syndrome: lessons learned and future prospects. 1259 93

Lipopolysaccharides (LPSs) play a dual role as inflammation-inducing and as membrane-forming molecules. The former role attracts significantly more attention from scientists, possibly because it is more closely related to sepsis and septic shock. This review aims to focus the reader's attention to the other role, the function of LPS as the major constituent of the outer layer of the outer membrane of Gram-negative bacteria, in particular those of enterobacterial strains. In this function, LPS is a necessary component of the cell envelope and guarantees survival of the bacterial organism. At the same time, it represents the first target for attacking molecules which may either be synthesized by the host's innate or adaptive immune system or administered to the human body. The interaction of these molecules with the outer membrane may not only directly cause the death of the bacterial organism, but may also lead to the release of LPS into the circulation. Here, we review membrane model systems and their application for the study of molecular mechanisms of interaction of peptides such as those of the human complement system, the bactericidal/permeability-increasing protein (BPI), cationic antibacterial peptide 18 kDa (CAP18) as an example of cathelicidins, defensins, and polymyxin B (PMB). Emphasis is on electrical measurements with a reconstitution system of the lipid matrix of the outer membrane which was established in the authors' laboratory as a planar asymmetric bilayer with one leaflet being composed solely of LPS and the other of the natural phospholipid mixture. The main conclusion, which can be drawn from these investigations, is that LPS and in general its negative charges are the dominant determinants for specific peptide-membrane interactions. However, the detailed mechanisms of interaction, which finally lead to bacterial killing, may involve further steps and differ for different antibacterial peptides.
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PMID:Towards antibacterial strategies: studies on the mechanisms of interaction between antibacterial peptides and model membranes. 1280 79

The incidence of sepsis and SIRS, respectively is still rising. Mortality is 40 to 70% and, thus, remains very high in spite of major advances in intensive care medicine. Numerous experimental data have helped to explain isolated aspects of the pathophysiology of these disease states but the complex patho-mechanism remains to be elucidated. The discovery of the toll-like receptors and of the endotoxin-binding proteins LBP and BPI have substantially contributed to the understanding of the bacterial toxin-host interactions and may stimulate the development of new therapeutic strategies in the future. Pro- and anti-inflammatory cytokines play a central role in disease evolution, however the concept of organ-derived and organ-specific damage is gaining importance. Both inflammation and counter-regulation can occur at the same time in the circulation thus, making the evaluation of the patients' immunological status difficult. Additionally, several gene polymorphisms have been detected for example within the toll-like receptor genes and TNF genes. These polymorphisms document the existence of pre-disposing factors, which influence acute phase reaction as well as immuno-competence in sepsis. Both genes and gender will play an important role in the future to identify patients at risk and potentially, to design a specific and individualized immuno-therapies.
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PMID:[Acute phase reaction and immunocompetence in sepsis and SIRS]. 1550 51

Stenotrophomonas maltophilia is an emerging pathogen implicated in an increasing number of severe pulmonary infections and nosocomial sepsis. We evaluated the influence of four different antibiotics on the bacterial count and LPS activity found in broth cultures of S. maltophilia. After 4 h ceftazidime (CTZ) decreased live bacteria but increased endotoxin activity, whilst isepamicin (ISE), tobramycin (TB), and polymyxin B (PB) reduced both of them. We also investigated the influence of the above mentioned antibiotics on the ability of S. maltophilia culture filtrates and S. maltophilia LPS, extracted in our laboratory, to stimulate sepsis mediators such as tumor necrosis factor a (TNF-a), interleukin 8 (IL-8), interleukin 10 (IL-10), Nitric Oxide (NO) and as bactericidal/permeability-increasing protein (BPI) in human whole blood. Our results demonstrated that both single polycationic antibiotics and the combination of two molecules are able to kill bacteria and neutralize released S. maltophilia LPS. Combination between beta-lactams and aminoglycosides is often able to reduce the pro-inflammatory effects of S. maltophilia culture filtrates.
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PMID:Stenotrophomonas maltophilia lipopolysaccharide (LPS) and antibiotics: "in vitro" effects on inflammatory mediators. 1572 12

Neutrophils can be primed by bacterial lipopolysaccharide (LPS) for an enhanced oxidative burst, which is a key element in the pathogenesis of Gram-negative sepsis. Some serum proteins (e.g. lipopolysaccharide-binding protein) avidly bind LPS and markedly enhance receptor binding and cellular activation while other serum factors (lipoproteins, bactericidal/permeability-increasing protein) neutralize LPS and prevent neutrophil activation. In this paper we examined the kinetics of this priming reaction in whole blood. To study the balance between neutrophil activation and LPS neutralization a sensitive chemiluminescence assay was used in a whole blood system. LPS was able to prime neutrophils for enhanced oxidative burst in whole blood with an optimum incubation time of 25 min. However, LPS was neutralized very rapidly with a t(1/2) of 10 min. After 20 min a second priming factor was already generated, which was shown to be monocyte-derived tumour necrosis factor (TNF).
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PMID:The role of tumour necrosis factor in the kinetics of lipopolysaccharide-mediated neutrophil priming in whole blood. 1576 76

Intubation and mechanical ventilation after burn contribute to pneumonia-related infection. Although postburn presence or absence of endotoxin has been described, inactivation of Toll-like receptor 4 signaling has been shown to improve postburn organ function, suggesting that LPS participates in burn-related susceptibility to infection. We hypothesized that bactericidal/permeability-increasing protein (rBPI) given postburn would attenuate myocardial inflammation/dysfunction associated with postburn septic challenge given 7 days postburn. Rats were given burn over 40% total body surface area, lactated Ringer 4 ml.kg(-1).% burn(-1); burns received either vehicle or rBPI, 1 mg.kg(-1).h(-1) for 48 h postburn. Postburn day 7, subgroups of burns and shams were given intratracheal Klebsiella pneumoniae, 4 x 10(6) CFU to produce burn complicated by sepsis; additional sham and burn subgroups received intratracheal vehicle to produce sham sepsis. Vehicle-treated groups: 1) sham burn + sham sepsis 2) sham burn + sepsis, 3) burn + sham sepsis, 4) burn + sepsis. rBPI-treated groups: 5) sham burn + sham sepsis, 6) sham burn + sepsis, 7) burn + sham sepsis, 8) burn + sepsis. Cardiomyocyte cytokine secretion and myocardial function were studied 24 h after septic challenge, postburn day 8. Pneumonia-related infection 8 days after vehicle-treated burn produced myocyte cytokine secretion (pg/ml), indicated by increased myocyte TNF-alpha, 549 +/- 46; IL-1beta, 50 +/- 8; IL-6, 286 +/- 3 levels compared with levels in sham myocytes (TNF-alpha, 88 +/- 11; IL-1beta, 7 +/- 1; IL-6, 74 +/- 10; P < 0.05). Contractile dysfunction was evident from lower left ventricular pressure +/-dP/dt values in this group compared with sham. rBPI attenuated myocyte cytokine responses to septic challenge and improved contractile function, suggesting that burn-related mobilization of microbial-like products contribute to postburn susceptibility to infection.
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PMID:Bactericidal/permeability increasing protein attenuates the myocardial inflammation/dysfunction that occurs with burn complicated by subsequent infection. 1758 43

We investigated in vivo the effect of recombinant bactericidal/permeability-increasing protein (rBPI21) on high-mobility group box 1 protein (HMGB1) expression in sepsis and its potential mechanism. Using a sepsis model induced by cecal ligation and puncture (CLP), rats were randomly divided into four groups as follows: normal control group, sham-operated group, CLP group, and BPI treatment group. Animals were killed at designated time points, and blood and tissue samples from liver, lungs, kidneys, and small intestine were harvested to determine related variables. In addition, we observed the effect of treatment with rBPI21 on survival rate in septic rats. The results showed that endotoxin content and expression levels of HMGB1 and LPS binding protein/CD14 mRNA in various organs were significantly increased at 12 and 24 h after CLP, which can be attenuated by treatment with rBPI21 (P<0.05-0.01). Meanwhile, treatment with rBPI21 in septic rats can markedly reduce serum alanine aminotransferase, creatinine levels, and pulmonary myeloperoxidase activity at 12 and 24 h after CLP, increase diamine oxidase activity at both time points (P<0.05-0.01), and improve the 1- to 10-day survival rates in animals subjected to CLP (P=0.012). These findings suggest that treatment with rBPI21 can significantly reduce endotoxin contents and expression levels of HMGB1 and LPS binding protein/CD14 mRNA in various organs in sepsis induced by CLP, and can protect against multiple organ damage resulting from sepsis. The effect of rBPI21 inhibiting HMGB1 gene expression in sepsis might be associated with endotoxin-dependent mechanisms.
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PMID:Recombinant bactericidal/permeability-increasing protein inhibits endotoxin-induced high-mobility group box 1 protein gene expression in sepsis. 1769 35

The inability to reduce the high mortality due to overwhelming bacterial infection and sepsis has prompted a search for new therapeutic agents. Among these may be a wide range of endogenous antibiotic polypeptides that are prominent components of effective antimicrobial host defences. One of these polypeptide antibiotics is the bactericidal/permeability-increasing protein (BPI), a protein of approximately 55kD which is present in human and other mammalian neutrophils. BPI is toxic for Gram-negative bacteria and binds to endotoxin, resulting in its clearance and neutralisation. A recombinant 21kD N-terminal BPI fragment is at least as active as holo-BPI and protects both animals and humans against the effects of Gram-negative infections and their complications. Phase II/III clinical trials in fulminant paediatric meningococcaemia, haemorrhagic trauma, hepatectomy and severe peritoneal infections are in progress.
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PMID:Recent advances in therapy of sepsis: focus on recombinant bactericidal/permeability-increasing protein (BPI). 1802 May 76

Antibacterial properties of secreted phospholipases A2 (PLA2) have emerged gradually. Group (G) IIA PLA2 is the most potent among mammalian secreted (s) PLA2s against Gram-positive bacteria, but additional antibacterial compounds, e.g. the bactericidal/permeability-increasing protein, are needed to kill Gram-negative bacteria. The mechanisms of binding to the bacterial surface and the killing of bacteria by sPLA2s are based on the positive charge of the PLA2 protein and its phospholipolytic enzymatic activity, respectively. The concentration of GIIA PLA2 is highly elevated in serum of patients with bacterial sepsis, and overexpression of GIIA PLA(2) protects transgenic mice against experimental Gram-positive infection. The synthesis and secretion of GIIA PLA2 are stimulated by the cytokines TNF-alpha, IL-1 and IL-6. Secreted PLA2s may be potentially useful new endogenous antibiotics to combat infections including those caused by antibiotic-resistant bacteria such as methicillin-resistant staphylococci and vancomysin-resistant enterococci.
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PMID:Antibacterial actions of secreted phospholipases A2. Review. 1817 47

Septic or endotoxic shock is a common cause of death in hospital intensive care units. In the last decade numerous antimicrobial peptides and proteins have been tested in the search for an efficient drug to treat this lethal disease. Now in phase III clinical trials, rBPI(21), a recombinant N-terminal fragment of the bactericidal/permeability-increasing protein (BPI), is a promising drug to reduce lesions caused by meningococcal sepsis. We correlated structural and stability data with functional information of rBPI(21) bound to both model systems of eukaryotic and bacterial membranes. On interaction with membranes, rBPI(21) loses its conformational stability, as studied by circular dichroism. This interaction of rBPI(21) at membrane level was higher in the presence of negatively charged phospholipid relatively to neutral ones, with higher partition coefficients (K(p)), suggesting a preference for bacterial membranes over mammalian membranes. rBPI(21) binding to membranes is reinforced when its disulfide bond is broken due to conformational changes of the protein. This interaction is followed by liposome aggregation due to unfolding, which ensures protein aggregation, and interfacial localization of rBPI(21) in membranes, as studied by extensive quenching by acrylamide and 5-deoxylstearic acid and not by 16-deoxylstearic acid. An uncommon model of the selectivity and mechanism of action is proposed, where membrane induces unfolding of the antimicrobial protein, rBPI(21). The unfolding ensures protein aggregation, established by protein-protein interaction at membrane surface or between adjacent membranes covered by the unfolded protein. This protein aggregation step may lead to membrane perturbation.
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PMID:Fold-unfold transitions in the selectivity and mechanism of action of the N-terminal fragment of the bactericidal/permeability-increasing protein (rBPI(21)). 1918 36


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