lipid-a and Sepsis

Sepsis, defined as a clinical syndrome brought about by an amplified and dysregulated inflammatory response to infections, is one of the leading causes of death worldwide. Despite persistent attempts to develop treatment strategies to manage sepsis in the clinical setting, the basic elements of treatment have not changed since the 1960s. As such, the development of effective therapies for reducing inflammatory reactions and end-organ dysfunction in critically ill patients with sepsis remains a global priority. Advances in understanding of the immune response to sepsis provide the opportunity to develop more effective pharmaceuticals. This article details current information on the modulation of the lipopolysaccharide (LPS) receptor complex with synthetic Lipid A mimetics. As the initial and most critical event in sepsis pathophysiology, the LPS receptor provides an attractive target for antisepsis agents. One of the well-studied approaches to sepsis therapy involves the use of derivatives of Lipid A, the membrane-anchor portion of an LPS, which is largely responsible for its endotoxic activity. This article describes the structural and conformational requirements influencing the ability of Lipid A analogues to compete with LPS for binding to the LPS receptor complex and to inhibit the induction of the signal transduction pathway by impairing LPS-initiated receptor dimerization.

Topics: Animals; Cytokines; Drug Design; Endotoxins; Humans; Immune System; Inflammation; Lipid A; Lipopolysaccharide Receptors; Lipopolysaccharides; Mice; Molecular Conformation; Phosphorylation; Protein Binding; Sepsis; Signal Transduction; Solubility; Thromboplastin; Tumor Necrosis Factor-alpha

This paper concerns the potential use of compounds, including lipid A, chitosan, and carrageenan, from marine sources as agents for treating endotoxemic complications from Gram-negative infections, such as sepsis and endotoxic shock. Lipid A, which can be isolated from various species of marine bacteria, is a potential antagonist of bacterial endotoxins (lipopolysaccharide (LPSs)). Chitosan is a widespread marine polysaccharide that is derived from chitin, the major component of crustacean shells. The potential of chitosan as an LPS-binding and endotoxin-neutralizing agent is also examined in this paper, including a discussion on the generation of hydrophobic chitosan derivatives to increase the binding affinity of chitosan to LPS. In addition, the ability of carrageenan, which is the polysaccharide of red alga, to decrease the toxicity of LPS is discussed. We also review data obtained using animal models that demonstrate the potency of carrageenan and chitosan as antiendotoxin agents.

Topics: Animals; Anti-Bacterial Agents; Aquatic Organisms; Carrageenan; Chitosan; Endotoxemia; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans; Lipid A; Sepsis

Lipopolysaccharide (LPS) or endotoxin, the major constituent of the outer membrane of Gram negative bacteria, has been implicated as the bacterial product responsible for the clinical syndrome of sepsis. LPS binding to the host receptor Toll-like receptor 4 (TLR4) triggers an inflammatory reaction characterised by the release of large number of inflammatory mediators that allow the host to respond to the invading pathogen. When this production becomes un-controlled and excessive, it leads to the development of septic shock. Despite decades of efforts in supporting therapies, sepsis remains the leading cause of death amongst critically ill patients. Unfortunately, the major factor contributing to the high morbidity and mortality of sepsis is the lack of the effective targeted treatment. Indeed, over 30 drugs for the treatment of sepsis have been developed: many of these target specific inflammatory mediators and have thus been, in general, unsuccessful since sepsis relies on the cross talk of several cytokines and the block of a single factor has been proven to be ineffective. More successful strategies include those modulating the early phase of LPS signalling such as the ones that prevent the binding of LPS to host cells and the subsequent cascade of detrimental events. In this light, effective LPS antagonists would represent invaluable tools to efficaciously manage sepsis. This review discusses the evolution of naturally occurring and synthetic LPS antagonists with emphasis on the development of several natural new molecules.

Topics: Animals; Humans; Lipid A; Lipopolysaccharides; Molecular Structure; Sepsis; Signal Transduction

Eisai Co Ltd is developing the injectable endotoxin antagonist E-5564, for the potential prevention of the pathophysiological effects of endotoxin-mediated responses caused by bacterial infection, including septic shock.

Topics: Animals; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Endotoxemia; Endotoxins; Humans; Lipid A; Randomized Controlled Trials as Topic; Sepsis; Structure-Activity Relationship

Despite considerable efforts in the past quarter century to improve therapy for sepsis, mortality rates remain unacceptably high. Microbe-derived constituents can induce the host to produce many mediators that can contribute to immune dysregulation, tissue damage, and death. Although endotoxin-mediated events are clearly important in gram-negative infections, gram-positive bacteria can also play a dominant role. Understanding the interplay of microbial constituents and host immune or inflammatory responses prompted a meeting at Rockefeller University in May 1998. Participants discussed the relative merits of a "2-hit" hypothesis to explain the course of lethal septic shock and a "multihit" synergistic threshold hypothesis. Recommendations include the following: (1) developing animal models that closely mimic human sepsis; (2) further investigating antibiotic effects on bacteria; (3) assessing the relationships between endotoxin, prokaryotic DNA, and peptidoglycan (i.e., independent, additive, or synergistic) in inducing host responses; and (4) developing new strategies to improve outcomes. Studies are needed to better define which and how different microbial constituents lead to sepsis and to provide critical leads for therapeutic intervention.

Topics: Amino Acid Sequence; Animals; Carbohydrate Sequence; Disease Models, Animal; DNA, Bacterial; Endotoxins; Gram-Positive Bacteria; Humans; Inflammation Mediators; Lipid A; Models, Biological; Peptidoglycan; Sepsis

A substantial body of knowledge has emerged over the past several decades concerning the primary and tertiary, and quaternary structure of endotoxic LPS and their contribution to the pathogenesis of gram-negative sepsis; however, important questions remain. Among them are the precise three-dimensional configuration of the LPS macromolecule and the contribution of the quaternary structure to the ability of these potent microbial factors to interact with host humoral and cellular inflammatory mediator systems. Also remaining to be sufficiently addressed is the relative contribution of endotoxin interactions with the host to the overall manifestation of disease and conditions under which such contributions serve as the pivotal event in determining outcome. The answers to these questions can be expected to provide valuable insights into potential novel therapeutic intervention strategies and approaches that will ultimately reduce both morbidity and mortality in infection from gram-negative microbes.

Topics: Animals; Bacterial Infections; Endotoxins; Humans; Lipid A; Lipopolysaccharides; Sepsis; Structure-Activity Relationship

The identification of lipopolysaccharide binding protein (LBP) and CD14 as key molecules in the cellular response to endotoxin has been a major advance in unravelling the pathophysiological basis of Gram-negative sepsis. Much interest has focused on developing effective anti-endotoxin treatments to abrogate the inflammatory consequences of Gram-negative infection. The therapeutic options can be divided into those aimed at neutralizing or clearing circulating endotoxin, including anti-endotoxin antibodies and endotoxin neutralizing proteins, and those that antagonize the effects of endotoxin on human cells--for example, lipid A analogues. Initial experiences with anti-lipopolysaccharide antibodies have been disappointing but a new generation of anti-endotoxin agents is about to enter clinical trials. Whether these will prove sufficiently effective to reduce the morbidity and mortality of Gram-negative sepsis remains to be seen.

Topics: Endothelium; Endotoxins; Humans; Immunity, Cellular; Immunization, Passive; Immunoglobulins; Immunotherapy; Lipid A; Lipopolysaccharide Receptors; Macrophages; Neutrophils; Sepsis; Signal Transduction

Antibiotic-resistant bacterial infections are a major clinical problem. Lipid A, the active part of lipopolysaccharide endotoxins in Gram-negative bacteria, is an intriguing target for new antibacterial and anti-inflammatory agents. Inhibition of lipid A biosynthesis kills most Gram-negative bacteria, increases bacterial permeability to antibiotics and decreases endotoxin production.

Topics: Animals; Anti-Bacterial Agents; Anti-Inflammatory Agents; Carbohydrate Sequence; Gram-Negative Bacterial Infections; Humans; Lipid A; Molecular Sequence Data; Sepsis

Topics: Animals; Bacterial Infections; Clinical Trials as Topic; Humans; Lipid A; Mice; Safety; Sepsis; Shock, Septic; Structure-Activity Relationship

Topics: Endotoxins; Gram-Negative Bacterial Infections; Humans; Immunization, Passive; Lipid A; Sepsis

Topics: Chemical Phenomena; Chemistry; Endotoxins; Humans; Lipid A; Lipopolysaccharides; Prostaglandins; Sepsis

Lipopolysaccharide (LPS) and monophosphoryl lipid A (MPLA) induce, overall, similar transcriptional profiles in healthy individuals, although LPS has been shown to more potently induce pro-inflammatory cytokines. We explore herein whether MPLA could be considered as a synthetic replacement of LPS in immune functional assays to study anergy of immune cells in septic patients. Ex vivo whole blood stimulation with MPLA revealed a lower induction of the TNFα secreted protein in 20 septic patients (SP) compared to 10 healthy volunteers (HV), in agreement with monocyte anergy. Principal component analysis of the 93-gene molecular response to MPLA and LPS stimulation found that the main variability was driven by stimulation in HV and by pathophysiology in SP. MPLA was a stronger inducer of the HLA family genes than LPS in both populations, arguing for divergent signalling pathways downstream of TLR-4. In addition, MPLA appeared to present a more informative stratification potential within the septic population.

Topics: Aged; Aged, 80 and over; Cytokines; Female; Humans; Immunocompromised Host; Inflammation; Lipid A; Lipopolysaccharides; Male; Monocytes; Prospective Studies; Sepsis; Signal Transduction; Toll-Like Receptor 4; Tumor Necrosis Factor-alpha

Endotoxin is a potent stimulus of proinflammatory response and systemic coagulation in patients with severe sepsis. Endotoxin is a component of Gram-negative bacteria that triggers an innate immune response through Toll-like receptor 4 signaling pathways in myeloid cells. We evaluated safety and tolerability of two dose regimens of eritoran tetrasodium (E5564), a synthetic Toll-like receptor 4 antagonist, and explored whether it decreases 28-day mortality rate in subjects with severe sepsis.. Prospective, randomized, double-blind, placebo-controlled, multicenter, ascending-dose phase II trial.. Adult intensive care units in the United States and Canada.. Three hundred adults within 12 hrs of recognition of severe sepsis, with Acute Physiology and Chronic Health Evaluation (APACHE) II-predicted risk of mortality between 20% and 80%.. Intravenous eritoran tetrasodium (total dose of either 45 mg or 105 mg) or placebo administered every 12 hrs for 6 days.. Prevalence of adverse events was similar among subjects treated with 45 mg or 105 mg of eritoran tetrasodium or with placebo. For modified intent-to-treat subjects, 28-day all-cause mortality rates were 26.6% (eritoran tetrasodium 105 mg), 32.0% (eritoran tetrasodium 45 mg), and 33.3% in the placebo group. Mortality rate in the eritoran tetrasodium 105-mg group was not significantly different from placebo (p = .335). In prespecified subgroups, subjects at highest risk of mortality by APACHE II score quartile had a trend toward lower mortality rate in the eritoran tetrasodium 105-mg group (33.3% vs. 56.3% placebo group, p = .105). A trend toward a higher mortality rate was observed in subjects in the lowest APACHE II score quartile for the eritoran 105-mg group (12.0% vs. 0.0% placebo group, p = .083).. Eritoran tetrasodium treatment appears well tolerated. The observed trend toward a lower mortality rate at the 105-mg dose, in subjects with severe sepsis and high predicted risk of mortality, should be further investigated.

Topics: Adult; Aged; APACHE; Bacterial Infections; Cohort Studies; Critical Care; Critical Illness; Dose-Response Relationship, Drug; Double-Blind Method; Drug Administration Schedule; Female; Follow-Up Studies; Hospital Mortality; Humans; Infusions, Intravenous; Intensive Care Units; Lipid A; Male; Maximum Tolerated Dose; Middle Aged; Prospective Studies; Risk Assessment; Sepsis; Survival Analysis; Toll-Like Receptor 4; Treatment Outcome

Topics: Anti-Inflammatory Agents; APACHE; Cause of Death; Critical Care; Critical Illness; Female; Hospital Mortality; Humans; Intensive Care Units; Lipid A; Male; Prognosis; Risk Assessment; Sepsis; Survival Rate

Endotoxin is one of the principal mediators of Gram-negative septic shock. Pretreatment with monophosphoryl lipid A, a hydrolyzed derivative of endotoxin from Salmonella minnesota R595, induces endotoxin tolerance and nonspecific resistance to infection in experimental animals. The present clinical trial was undertaken to test the response to monophosphoryl lipid A in humans and the ability of monophosphoryl lipid A to attenuate the response of normal human volunteers to U.S. Reference Ec-5 endotoxin.. Prospective, double-blind, randomized, controlled trial.. Clinical research center.. Forty-four healthy volunteers.. In part 1 of the study, 29 volunteers were randomized in varying ratios to receive vehicle control or monophosphoryl lipid A intravenously in a double-blind dose escalation trial. In part 2 of the study, 12 volunteers were randomized to receive either monophosphoryl lipid A (20 micrograms/kg) or vehicle control and, 24 hrs later, all 12 volunteers were challenged with U.S. Reference Ec-5 endotoxin (20 units/kg intravenous, bolus injection). Systemic response to endotoxin challenge was evaluated and compared between the monophosphoryl lipid A and vehicle control-pretreated subjects.. In part 1 of the study, subjective effects and increases in cytokine levels were not observed until a dose of 10 micrograms/kg of monophosphoryl lipid A was administered. Six volunteers receiving a maximum dose of 20 micrograms/kg experienced mild-to-moderate symptoms that did not require therapy. Moderate increases in temperature, heart rate, and tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8 release were observed. IL-1 alpha and IL-1 beta were not detected but a significant increase in IL-1 receptor antagonist was observed. In part 2 of the study, monophosphoryl lipid A pretreatment reduced the number of volunteers who experienced one or more subjective complaints after endotoxin administration (3/6 vs. 6/6; p = .09). The febrile response and tachycardic response to endotoxin were significantly reduced by pretreatment with monophosphoryl lipid A. Monophosphoryl lipid A-pretreated volunteers demonstrated significantly reduced concentrations of TNF-alpha after endotoxin challenge, as compared with subjects treated with vehicle control (84 +/- 76 vs. 244 +/- 128 pg/mL; p < .05). IL-6 concentrations (100 +/- 91 vs. 268 +/- 171 pg/ml; p < .05) and IL-8 concentrations (136 +/- 86 vs. 632 +/- 323 pg/mL; p < .05) elicited by endotoxin challenge were also significantly reduced by monophosphoryl lipid A pretreatment.. Data indicate that monophosphoryl lipid A, in a dose 10,000 times that of endotoxin, used in experimental pyrogenicity trials, is well tolerated in human volunteers. Pretreatment of normal human volunteers with monophosphoryl lipid A attenuated the systemic response to bacterial endotoxin. These data support further clinical testing of monophosphoryl lipid A for the prevention or amelioration of the severe sequelae of sepsis.

Topics: Adolescent; Adult; Blood Cell Count; Body Temperature; Catecholamines; Cytokines; Double-Blind Method; Endotoxins; Escherichia coli; Heart Rate; Humans; Hydrocortisone; Immune Tolerance; Infusions, Intravenous; Lipid A; Male; Prospective Studies; Sepsis

Topics: Endotoxins; Gram-Negative Bacterial Infections; Humans; Immunization, Passive; Lipid A; Sepsis

Topics: Antibodies, Monoclonal; Gram-Negative Bacteria; Humans; Lipid A; Sepsis

HA-1A, a human monoclonal immunoglobulin M antibody that binds specifically to the lipid A domain of endotoxin, was administered to septic patients to evaluate the safety, pharmacokinetics, and immunogenicity of the antibody. Thirty-four patients received a single infusion of either 25 mg, 100 mg, or 250 mg, and were followed clinically for 14 to 21 days after treatment. HA-1A serum levels were measured before infusion and frequently after infusion with a radiometric assay. A one-compartment pharmacokinetic model was fit to the measured serum levels, and accurately described the changes in HA-1A level over time in each dose group (r2 = .99). The mean +/- SEM apparent volume of distribution of HA-1A was 48.5 +/- 4.5 ml/kg, and the mean serum clearance was 2.8 +/- 0.4 ml/kg.h. The mean serum half-life of HA-1A was 15.9 +/- 1.5 h. The mean serum level one hour after a 100-mg dose was 33.2 +/- 2.4 micrograms/ml, and the mean concentration 24 h later was 9.1 +/- 1.6 micrograms/ml. The dose administered and presence of Gram-negative bacterial infection did not significantly influence the volume of distribution or serum clearance. No adverse reactions to HA-1A were observed, and no antibodies against HA-1A were detected in any patient. These data indicate that the pharmacokinetics of HA-1A are well described by a one-compartment pharmacokinetic model, and that HA-1A is safe and nonimmunogenic in patients with sepsis.

Topics: Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal; Bacterial Proteins; Dose-Response Relationship, Immunologic; Endotoxins; Female; Gram-Negative Bacteria; Humans; Lipid A; Male; Middle Aged; Models, Chemical; Pilot Projects; Sepsis

Topics: Antibodies, Bacterial; Antibodies, Monoclonal; Clinical Trials as Topic; Endotoxins; Gram-Negative Bacteria; Humans; Immunization; Lipid A; Lipopolysaccharides; Sepsis; Shock, Septic

Topics: Adult; Aged; Antibodies, Bacterial; Antibodies, Monoclonal; Bacterial Infections; Clinical Trials as Topic; Female; Gram-Negative Bacteria; Humans; Kinetics; Lipid A; Male; Middle Aged; Sepsis

To develop a suitable and effective vaccine against Staphylococcus aureus (S. aureus), we selected the Hla-MntC-SACOL0723 (HMS) recombinant protein with two different formulations of alum and Monophosphoryl lipid A (MPL) adjuvants. In this study, we aimed to evaluate the potentials of alum and MPL adjuvants in stimulating the immune response of HMS vaccine candidate against S. aureus. To evaluate the type of induced immune response, anti-HMS total IgG, IgG1, IgG2a, and IFN-γ, IL-2, IL-4, and IL-17 cytokines were determined after vaccination of mice with HMS-alum, HMS-MPL candidates. Mice were challenged with Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from pressure sores and evaluated for bacterial load in the kidney homogenates and survival rate. It was observed that total IgG and isotypes (IgG1 and IgG2a), IL-4, and IL-17 were significantly increased in the group that received HMS-alum vaccine compared with the group that received HMS-MPL formulation. On the other hand, the levels of IFN-γ and IL-2 cytokines in the group that received HMS-MPL were higher than the group that received HMS-alum formulation. Bacterial load in the mice who received HMS protein formulated with alum adjuvant was reduced more than the mice who received HMS protein formulated with MPL adjuvant. Histopathological analysis showed more pathological changes in kidney tissues of the group received of HMS-MPL compared with the HMS-alum formulation. The survival rate was equal in both groups of immunized with HMS-alum and HMS-MPL formulations. Finally, it could be concluded that both adjuvants of alum and MPL are suitable immune response enhancers to HMS vaccine candidate.

Topics: Alum Compounds; Animals; Female; HLA Antigens; Immunoglobulin G; Interleukin-17; Interleukin-4; Kidney; Lipid A; Methicillin-Resistant Staphylococcus aureus; Mice; Mice, Inbred BALB C; Periplasmic Binding Proteins; Recombinant Fusion Proteins; Sepsis; Staphylococcal Infections; Staphylococcal Vaccines; Staphylococcus aureus; Up-Regulation

Sepsis is the leading cause of acute kidney injury in critically ill patients. Tumor necrosis factor-α (TNF-α) has been implicated in the pathogenesis of septic kidney injury; however, the sites and mechanisms of renal TNF-α production during sepsis remain to be defined. In the present study, we showed that TNF-α expression is increased in medullary thick ascending limbs (MTALs) of mice with sepsis induced by cecal ligation and puncture. Treatment with lipopolysaccharide (LPS) for 3 h in vitro also increased MTAL TNF-α production. Sepsis and LPS increased MTAL TNF-α expression through activation of the myeloid differentiation factor 88 (MyD88)-IL-1 receptor-associated kinase 1-ERK signaling pathway. Pretreatment with monophosphoryl lipid A (MPLA), a nontoxic immunomodulator that protects against bacterial infection, eliminated the sepsis- and LPS-induced increases in MTAL TNF-α production. The suppressive effect of MPLA on TNF-α was mediated through activation of a phosphatidylinositol 3-kinase-dependent pathway that inhibits MyD88-dependent ERK activation. This likely involves MPLA-phosphatidylinositol 3-kinase-mediated induction of Tollip, which negatively regulates the MyD88-ERK pathway by inhibiting activation of IL-1 receptor-associated kinase 1. These regulatory mechanisms are similar to those previously shown to mediate the effect of MPLA to prevent sepsis-induced inhibition of MTAL [Formula: see text] absorption. These results identify the MTAL as a site of local TNF-α production in the kidney during sepsis and identify molecular mechanisms that can be targeted to attenuate renal TNF-α expression. The ability of MPLA pretreatment to suppress MyD88-dependent ERK signaling in the MTAL during sepsis has the dual beneficial effects of protecting tubule transport functions and attenuating harmful proinflammatory responses.

Topics: Animals; Cytokines; Kidney Medulla; Lipid A; Lipopolysaccharides; Loop of Henle; Male; Mice; Mice, Knockout; Myeloid Differentiation Factor 88; Sepsis; Signal Transduction

Sepsis is a major cause of patient mortality and morbidity from bacterial infections. Although neutrophils are known to be important in the development of sepsis, how distinctive neutrophil subtypes regulate inflammatory processes involved in septicemia remains unclear. Preconditioning protects organisms against subsequent higher-dose exposures to the same, or even different, stimuli. Several studies have reported various effects of preconditioning on immune cells. However, the detailed mechanisms underlying neutrophil-mediated protection through preconditioning in sepsis remain unknown.

Topics: Animals; Bacterial Infections; Caveolin 1; Cell Membrane; Humans; Lipid A; Mice; Neutrophils; Sepsis; Signal Transduction; Toll-Like Receptor 9

LPS inhibits

Topics: Adaptor Proteins, Vesicular Transport; Adjuvants, Immunologic; Animals; Bicarbonates; Cytoprotection; Disease Models, Animal; Extracellular Signal-Regulated MAP Kinases; Interleukin-1 Receptor-Associated Kinases; Intracellular Signaling Peptides and Proteins; Lipid A; Loop of Henle; Mice, Inbred C57BL; Mice, Knockout; Myeloid Differentiation Factor 88; Phosphatidylinositol 3-Kinase; Phosphorylation; Rats, Sprague-Dawley; Renal Reabsorption; Sepsis; Signal Transduction; Toll-Like Receptor 4

Endotoxicity originating from a dangerous debris (i.e., lipopolysaccharide, LPS) of Gram-negative bacteria is a challenging clinical problem, but no drugs or therapeutic strategies that can successfully address this issue have been identified yet. In this study, we report a subnanometer gold cluster that can efficiently block endotoxin activity to protect against sepsis. The endotoxin blocker consists of a gold nanocluster that serves as a flakelike substrate and a coating of short alkyl motifs that act as an adhesive to dock with LPS by compacting the intramolecular hydrocarbon chain-chain distance ( d-spacing) of lipid A, an endotoxicity active site that can cause overwhelming cytokine induction resulting in sepsis progression. Direct evidence showed the d-spacing values of lipid A to be decreased from 4.19 Å to either 3.85 or 3.54 Å, indicating more dense packing densities in the presence of subnanometer gold clusters. In terms of biological relevance, the concentrations of key pro-inflammatory NF-κB-dependent cytokines, including plasma TNF-α, IL-6, and IL-1β, and CXC chemokines, in LPS-challenged mice showed a noticeable decrease. More importantly, we demonstrated that the treatment of antiendotoxin gold nanoclusters significantly prolonged the survival time in LPS-induced septic mice. The ultrasmall gold nanoclusters could target lipid A of LPS to deactivate endotoxicity by compacting its packing density, which might constitute a potential therapeutic strategy for the early prevention of sepsis caused by Gram-negative bacterial infection.

Topics: Animals; Cytokines; Gold; Lipid A; Lipopolysaccharides; Male; Metal Nanoparticles; Mice; Mice, Inbred C57BL; Sepsis

Metabolic acidosis is the most common acid-base disorder in septic patients and is associated with increased mortality. Previously, we demonstrated that sepsis induced by cecal ligation and puncture (CLP) impairs [Formula: see text] absorption in the medullary thick ascending limb (MTAL) by 1) decreasing the intrinsic [Formula: see text] absorptive capacity and 2) enhancing inhibition of [Formula: see text] absorption by LPS through upregulation of Toll-like receptor (TLR) 4 signaling. Both effects depend on ERK activation. Monophosphoryl lipid A (MPLA) is a detoxified TLR4 agonist that enhances innate antimicrobial immunity and improves survival following sepsis. Pretreatment of MTALs with MPLA in vitro prevents LPS inhibition of [Formula: see text] absorption. Here we examined whether pretreatment with MPLA would protect the MTAL against sepsis. Vehicle or MPLA was administered to mice 48 h before sham or CLP surgery, and MTALs were studied in vitro 18 h postsurgery. Pretreatment with MPLA prevented the effects of sepsis to decrease the basal [Formula: see text] absorption rate and enhance inhibition by LPS. These protective effects were mediated through MPLA stimulation of a Toll/IL-1 receptor domain-containing adaptor-inducing IFN-β-(TRIF)-dependent phosphatidylinositol 3-kinase-Akt pathway that prevents sepsis- and LPS-induced ERK activation. The effects of MPLA to improve MTAL [Formula: see text] absorption were associated with marked improvement in plasma [Formula: see text] concentration, supporting a role for the kidneys in the pathogenesis of sepsis-induced metabolic acidosis. These studies support detoxified TLR4-based immunomodulators, such as MPLA, that enhance antimicrobial responses as a safe and effective approach to prevent or treat sepsis-induced renal tubule dysfunction and identify cell signaling pathways that can be targeted to preserve MTAL [Formula: see text] absorption and attenuate metabolic acidosis during sepsis.

Topics: Acid-Base Equilibrium; Acidosis; Adaptor Proteins, Vesicular Transport; Animals; Bicarbonates; Disease Models, Animal; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Lipid A; Loop of Henle; Male; Mice, Inbred C57BL; Mice, Knockout; Phosphatidylinositol 3-Kinase; Proto-Oncogene Proteins c-akt; Renal Reabsorption; Sepsis; Signal Transduction; Toll-Like Receptor 4

HuanglianJiedu decoction (HJD) is a classic prescription for heat-clearing away and detoxifying, which is used for the clinical treatment of sepsis, due to sepsis refers to the systemic inflammatory response induced by infection in western medicine, and infection belongs to the category of poison-heat syndrome in traditional Chinese medicine.. Previous study had elucidated the effective components from HJD with high affinity to lipid A, which can generate the release of pro-inflammatory-cytokines, resulting in sepsis. Now the anti-sepsis activities of these compounds were evaluated.. Immunofluorescence, immunohistochemical staining, ELISA and MTT methods were used to evaluated these compounds.. Immunofluorescence analysis evaluated the effects of compounds on the binding of FITC-LPS to RAW264.7 cells, and showed the fluorescence intensity was significant attenuated in geniposides, palmatine, baicalin and berberine groups (64 and 128 μg/mL) compared with model group (p < 0.05), which showed these compounds inhibit the combination of LPS with receptor of cells; immunohistochemical staining and ELISA method showed the TLR4 receptor expression, IL-6 and TNF-α levels were significant decreased in the groups treated with compounds, indicating that geniposides, baicalin, palmatine and berberine can play the role of anti-sepsis by inhibiting the expression of TLR4, the releasing of IL-6 and TNF-α; MTT assay showed that palmatine and berberine had a weak effect on cell viability, while others not, indicating that the compounds have protective activity.. It could be concluded the high affinity binding between these compounds and lipid A may be an important basis for its anti-LPS activity in vitro.

Topics: Animals; Berberine; Berberine Alkaloids; Cell Line; Drugs, Chinese Herbal; Flavonoids; Interleukin-6; Iridoids; Lipid A; Lipopolysaccharides; Mice; RAW 264.7 Cells; Sepsis; Toll-Like Receptor 4; Tumor Necrosis Factor-alpha

Huanglian Jiedu Decoction (HJD), one of the classic recipes for relieving toxicity and fever, is a common method for treating sepsis in China. However, the effective components of HJD have not yet been identified. This experiment was carried out to elucidate the effective components of HJD against sepsis. Thus, seven fractions from HJD were tested using a biosensor to test their affinity for lipid A. The components obtained that had high lipid A-binding fractions were further separated, and their affinities to lipid A were assessed with the aid of a biosensor. The levels of LPS in the blood were measured, and pathology experiments were conducted. The LPS levels and mRNA expression analysis of TNF-α and IL-6 of the cell supernatant and animal tissue were evaluated to investigate the molecular mechanisms. Palmatine showed the highest affinity to lipid A and was evaluated by in vitro and in vivo experiments. The results of the in vitro and in vivo experiments indicated that the levels of LPS, TNF-α and IL-6 of the palmatine group were significantly lower than those of the sepsis model group (p<0.01). The group treated with palmatine showed strong neutralizing LPS activity in vivo. The palmatine group exhibited stronger protective activity on vital organs compared to the LPS-induced animal model. This verifies that HJD is a viable treatment option for sepsis given that there are multiple components in HJD that neutralize LPS, decrease the release of IL-6 and TNF-α induced by LPS, and protect vital organs.

Topics: Animals; Berberine Alkaloids; Disease Models, Animal; Drugs, Chinese Herbal; Gene Expression Regulation; Humans; Interleukin-6; Lipid A; Lipopolysaccharides; Mice; Mice, Inbred BALB C; RAW 264.7 Cells; Sepsis; Toll-Like Receptor 4; Tumor Necrosis Factor-alpha

Huanglian Jiedu Decoction (HJD), the classical recipe for relieving fever and toxicity, has been used for treating sepsis in China for sixteen years. However, the effective components of HJD have not been elucidated until now. Therefore, there is a need to elucidate the effective components of HJD against sepsis on animal models induced by endotoxin (LPS). The affinity force of the effective components of HJD with lipid A was evaluated by a biosensor.. Lipid A is regarded as the bioactive center of LPS and is always used as a drug target. In order to obtain the effective components of HJD against sepsis, seven fractions from HJD were tested by a biosensor method for assessing the affinity for lipid A. After further separation, the components were isolated from high lipid A-binding fractions and their affinities to lipid A were assessed with the aid of a biosensor. Their activities were then assayed by an in vivo experiment administered through a tail vein injection. The levels of LPS, TNF-α, and IL-6 from the blood were found and pathology experiments were performed.. Three out of the seven fractions exhibited high lipid A-binding affinities. Berberine, baicalin and geniposide were obtained from the three high lipid A-binding fractions. The animal experiments indicated that the levels of LPS, TNF-α and IL-6 in the medicated treatment groups were much lower than that of the model group ((**)P<0.01). The medicated treatment groups exhibited stronger protective activities on varying organs in the animal model.. Berberine, baicalin and geniposide could neutralize LPS by binding with lipid A and then reduce the release of IL-6 and TNF-α induced by LPS. Furthermore, berberine, baicalin and geniposide exhibited protective activities on varying organs compared to the animal model established by the LPS-induced. These results validate that the components from HJD neutralized LPS and then depressed the release of IL-6 and TNF-α induced by LPS. This gives further evidence that HJD would be a suitable treatment for sepsis and protecting vital organs.

Topics: Animals; Berberine; Biosensing Techniques; Drugs, Chinese Herbal; Female; Flavonoids; Interleukin-6; Iridoids; Kidney; Lipid A; Lipopolysaccharides; Liver; Lung; Male; Mice, Inbred BALB C; Myocardium; Sepsis; Tumor Necrosis Factor-alpha

A combination therapy for combined injury (CI) using a non-specific immunomodulator, synthetic trehalose dicorynomycolate and monophosphoryl lipid A (STDCM-MPL), was evaluated to augment oral antimicrobial agents, levofloxacin (LVX) and amoxicillin (AMX), to eliminate endogenous sepsis and modulate cytokine production.. Female B6D2F(1)/J mice received 9.75 Gy cobalt-60 gamma-radiation and wound. Bacteria were isolated and identified in three tissues. Incidence of bacteria and cytokines were compared between treatment groups.. Results demonstrated that the lethal dose for 50% at 30 days (LD(50/30)) of B6D2F(1)/J mice was 9.42 Gy. Antimicrobial therapy increased survival in radiation-injured (RI) mice. Combination therapy increased survival after RI and extended survival time but did not increase survival after CI. Sepsis began five days earlier in CI mice than RI mice with Gram-negative species predominating early and Gram-positive species increasing later. LVX plus AMX eliminated sepsis in CI and RI mice. STDCM-MPL eliminated Gram-positive bacteria in CI and most RI mice but not Gram-negative. Treatments significantly modulated 12 cytokines tested, which pertain to wound healing or elimination of infection.. Combination therapy eliminates infection and prolongs survival time but does not assure CI mouse survival, suggesting that additional treatment for proliferative-cell recovery is required.

Topics: Amoxicillin; Animals; Anti-Infective Agents; Bacterial Infections; Chemokines; Cord Factors; Cytokines; Disease Models, Animal; Drug Therapy, Combination; Female; Gamma Rays; Growth Substances; Immunologic Factors; Levofloxacin; Lipid A; Mice; Radiation Injuries, Experimental; Sepsis; Skin; Wound Infection

LPS molecules of marine bacteria show structures distinct from terrestrial bacteria, due to the different environment that marine bacteria live in. Because of these different structures, lipid A molecules from marine bacteria are most often poor stimulators of the Toll-like receptor 4 (TLR4) pathway. Due to their low stimulatory potential, these lipid A molecules are suggested to be applicable as antagonists of TLR4 signaling in sepsis patients, where this immune response is amplified and unregulated. Antagonizing lipid A molecules might be used for future therapies against sepsis, therapies that currently do not exist. In this review, we will discuss these differences in lipid A structures and their recognition by the immune system. The modifications present in marine lipid A structures are described, and their potential as LPS antagonists will be discussed. Finally, since clinical trials built on antagonizing lipid A molecules have proven unsuccessful, we propose to also focus on different aspects of the TLR4 signaling pathway when searching for new potential drugs. Furthermore, we put forward the notion that bacteria probably already produce inhibitors of TLR4 signaling, making these bacterial products interesting molecules to investigate for future sepsis therapies.

Topics: Acylation; Humans; Lipid A; Protein Multimerization; Sepsis; Signal Transduction; Toll-Like Receptor 4; Water Microbiology

To investigate the therapeutic effect of E5564 (a clinically used TLR4 inhibitor) in murine abdominal sepsis elicited by intraperitoneal infection with a highly virulent Escherichia coli in the context of concurrent antibiotic therapy.. Mice were infected with different doses (~2 × 10(4)-2 × 10(6) CFU) of E. coli O18:K1 and treated after 8 h with ceftriaxone 20 mg/kg i.p. combined with either E5564 10 mg/kg i.v. or vehicle. For survival studies this treatment was repeated every 12 h. Bacterial loads and inflammatory parameters were determined after 20 h in peritoneal lavage fluid, blood, liver and lung tissue. Plasma creatinin, AST, ALT and LDH were determined to assess organ injury.. E5564 impaired bacterial clearance under the antibiotic regime after infection with a low dose E. coli (1.7 × 10(4) CFU) while renal function was slightly preserved. No differences were observed in bacterial load and organ damage after infection with a tenfold higher (1.7 × 10(5) E. coli) bacterial dose. While treatment with E5564 slightly attenuated inflammatory markers provoked by the sublethal doses of 104-105 E. coli under the antibiotic regime, it did not affect lethality evoked by infection with 1.7 × 106 E. coli.. The impact of TLR4 inhibition during abdominal sepsis by virulent E. coli bacteria is only beneficial at low infection grade at cost of bactericidal activity.

Topics: Animals; Anti-Bacterial Agents; Anti-Inflammatory Agents; Ascitic Fluid; Bacterial Load; Ceftriaxone; Cytokines; Escherichia coli; Escherichia coli Infections; Female; Lipid A; Liver; Lung; Mice, Inbred C57BL; Peritoneal Lavage; Peritonitis; Sepsis; Toll-Like Receptor 4

Gram-negative bacteria including Escherichia coli, Citrobacter rodentium, Salmonella typhimurium, and Shigella flexneri are sensed in an ill-defined manner by an intracellular inflammasome complex that activates caspase-11. We show that macrophages loaded with synthetic lipid A, E. coli lipopolysaccharide (LPS), or S. typhimurium LPS activate caspase-11 independently of the LPS receptor Toll-like receptor 4 (TLR4). Consistent with lipid A triggering the noncanonical inflammasome, LPS containing a divergent lipid A structure antagonized caspase-11 activation in response to E. coli LPS or Gram-negative bacteria. Moreover, LPS-mutant E. coli failed to activate caspase-11. Tlr4(-/-) mice primed with TLR3 agonist polyinosinic:polycytidylic acid [poly(I:C)] to induce pro-caspase-11 expression were as susceptible as wild-type mice were to sepsis induced by E. coli LPS. These data unveil a TLR4-independent mechanism for innate immune recognition of LPS.

Topics: Animals; Caspases; Caspases, Initiator; Cholera Toxin; Disease Models, Animal; Escherichia coli; Escherichia coli Infections; Immunity, Innate; Inflammasomes; Lipid A; Macrophages; Mice; Mice, Mutant Strains; Mutation; Salmonella Infections; Salmonella typhimurium; Sepsis; Toll-Like Receptor 4

The role of endotoxin in the genesis of sepsis has long been recognized and multiple treatments aimed at neutralizing it have been studied. Endotoxin can be bound by antibodies (whose role as a therapeutic agent is unlikely), binding proteins such as BPI or human lactoferrin (effectiveness debated and promising respectively) and phospholipid emulsion (which has not improved outcomes in a recent study). Alternatively, the action of endotoxin could be blocked by lipid A analogs (initial study showed no overall benefit and another large trial is near completion targeting a subpopulation of that study). Finally, endotoxin can be bound by polymyxin B embedded in hemoperfusion cartridges. The later treatment has been used for more than a decade in Japan. Since both pre-clinical rationale and studies support the targeting of endotoxin to ameliorate the pro-inflammatory and pro-coagulation response of severe sepsis, this therapeutic intervention is being pursued.

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Antibodies; Antimicrobial Cationic Peptides; Blood Proteins; Clinical Trials as Topic; Endotoxins; Humans; Lactoferrin; Lipid A; Polymyxin B; Sepsis

New glycolipids and a benzylammonium lipid were rationally designed by varying the chemical structure of a D-glucose-derived hit compound active as lipid A antagonist. We report the synthesis of these compounds, their in vitro activity as lipid A antagonists on HEK cells, and the capacity to inhibit LPS-induced septic shock in vivo. The lack of toxicity and the good in vivo activity suggest the use of some compounds of the panel as hits for antisepsis drug development.

Topics: Anti-Infective Agents; Benzylammonium Compounds; Cell Line; Drug Design; Glycolipids; Humans; Lipid A; Lipids; Sepsis; Shock, Septic; Structure-Activity Relationship

Bacterial DNA/CpG DNA is recognized as a key molecule during the pathogenesis of sepsis. Therefore, preventing CpG DNA from binding to its receptor is considered as the most promising strategy. In the present experiments, Radix et Rhizoma Rhei had the highest CpG DNA-binding ability among the seventy-eight traditional Chinese herbs. After the isolation of silica gel chromatography and high performance liquid chromatography (HPLC) and evaluation with affinity biosensor, the active fraction was confirmed and named Fraction D. It was found that in vitro, Fraction D bound to both CpG DNA and lipid A with high affinity, and strongly inhibited LPS- and CpG DNA-induced TNF-alpha release from RAW264.7 cells in a dose-dependent manner. Furthermore, Fraction D reduced the expression of TLR9 mRNA up-regulated by CpG DNA. In vivo, Fraction D protected mice challenged with lethal heat-killed E. coli. Using HPLC method, two monomers with high affinity for CpG DNA were isolated and identified as rhein and emodin. Rhein could significantly reduce CpG DNA- and LPS-induced TNF-alpha release, but emodin only reduced CpG DNA-induced TNF-alpha release. Rhein in combination with emodin could play synergistic inhibitory effect on both CpG DNA and LPS-induced TNF-alpha release, which contributed to the bioactivity of Fraction D. In conclusion, we successfully established the platform to screen anti-CpG DNA components of traditional Chinese herbs using affinity biosensor technology, got active Fraction D from Radix et Rhizoma Rhei and determined rhein and emodin as the main bioactive ingredients in Fraction D.

Topics: Aconitum; Animals; Anthraquinones; Biosensing Techniques; Cell Line; Chemical Fractionation; Chromatography, High Pressure Liquid; CpG Islands; DNA, Bacterial; Drug Evaluation, Preclinical; Drug Synergism; Drugs, Chinese Herbal; Emodin; Enzyme Inhibitors; Escherichia coli; Escherichia coli Infections; Female; Gene Expression Regulation; Immunity, Innate; Lipid A; Macrophages; Mice; Mice, Inbred Strains; Phytotherapy; Protein Binding; Sepsis; Toll-Like Receptor 9; Tumor Necrosis Factor-alpha

Lipopolysaccharide (LPS) is a known trigger in the pathogenesis of sepsis, lipid A being the toxic component. One of several adjuvant therapeutic approaches for severe sepsis is currently focusing on the neutralization of LPS. In order to obtain the components from traditional Chinese herbs that can neutralize the endotoxin, aqueous extractions of twelve herbs were tested using affinity biosensor technology. From twelve herbs, Scutellaria baicalensis Georgi (Huang Qin) found to possess high lipid A-binding abilities, and was selected in subsequent experiments. After subjected to macroporous adsorptive resins and HPLC, we obtained 2',5,6',7-tetrahydroxyflavanonol (THF) from S. baicalensis Georgi under the direction of neutralization of LPS and reducing proinflammatory cytokines. In vitro, THF directly bound to LPS and neutralized its activity. THF not only down-regulated TNF-alpha mRNA expression but also decreased TNF-alpha and IL-6 release from RAW264.7 cells induced by LPS in a dose-dependent manner. THF-mediated inhibition on proinflammatory cytokine release is probably associated with downregulation of LPS-induced TLR4 mRNA augmentation. In vivo, THF could significantly protect mice against a lethal challenge with heat-killed E. coli 35218 (E. coli 35218) in a dose-dependent manner, and decreased the plasma LPS level in endotoxemia mice. These findings provide compelling evidence that THF may be an important potential drug for sepsis treatment. Considering the inhibitory effects of THF on LPS-induced cytokine release are unlikely due to its nonspecific cellular toxicity, THF should be considered as a safe putative candidate for development as a drug for sepsis treatment.

Topics: Animals; Cell Line; Escherichia coli Infections; Female; Flavanones; Flavonoids; Interleukin-6; Lipid A; Lipopolysaccharides; Male; Mice; Scutellaria baicalensis; Sepsis; Toll-Like Receptor 4; Tumor Necrosis Factor-alpha

Sepsis and endotoxaemia are important causes of morbidity and mortality in humans. Research on sepsis focuses on rodent models most of which are poorly responsive to lipopolysaccharide (LPS), and thus do not mimic very well the high sensitivity of humans. Therefore, there is a need to develop more clinically relevant models. Horses suffer from a similar endotoxaemic syndrome to humans with high morbidity and mortality. LPS analogues that act as antagonists at Toll-like receptor 4 (TLR4) are being developed as novel treatments for endotoxaemia. Due to differences in recognition of ligands by TLR4 from different mammalian species, individual LPS molecules may act as agonists in some species and antagonists in others. The synthetic lipid A analogue E5531 is an antagonist at TLR4 in humans and mice, but its effects at TLR4 from other species are unknown. In the studies reported here, Escherichia coli LPS is a full agonist on equine bone marrow macrophage-like cells and its effects are antagonised by E5531. Similarly, E. coli LPS is an agonist and E5531 an antagonist on monocytes isolated from peripheral blood of healthy horses and human embryonic kidney (HEK) cells, transiently transfected to express horse TLR4 and its associated cell surface proteins MD2 and CD14. In contrast, both E. coli LPS and E5531 behave as agonists in horse whole blood by inducing production of equivalent amounts of the inflammatory mediator prostaglandin. This finding suggests that modification of E5531 may occur in whole blood, for example, deacylation, which alters its activity. This comparative study has revealed a novel pharmacological action of E5531 and emphasises the importance of extending studies of this nature beyond the normal rodent models.

Topics: Animals; Cell Line; Dinoprostone; Disease Models, Animal; Endotoxemia; Epoprostenol; Female; Humans; In Vitro Techniques; Interferon-gamma; Lipid A; Lipopolysaccharides; Male; Mice; Monocytes; Recombinant Proteins; Sepsis; Species Specificity; Toll-Like Receptor 4; Transfection

Klebsiella pneumoniae is an important cause of nosocomial Gram-negative sepsis. Lipopolysaccharide (LPS) is considered to be a major virulence determinant of this encapsulated bacterium and most mutations to the lipid A anchor of LPS are conditionally lethal to the bacterium. We studied the role of LPS acylation in K. pneumoniae disease pathogenesis by using a mutation of lpxM (msbB/waaN), which encodes the enzyme responsible for late secondary acylation of immature lipid A molecules. A K. pneumoniae B5055 (K2:O1) lpxM mutant was found to be attenuated for growth in the lungs in a mouse pneumonia model leading to reduced lethality of the bacterium. B5055DeltalpxM exhibited similar sensitivity to phagocytosis or complement-mediated lysis than B5055, unlike the non-encapsulated mutant B5055nm. In vitro, B5055DeltalpxM showed increased permeability of the outer membrane and an increased susceptibility to certain antibacterial peptides suggesting that in vivo attenuation may be due in part to sensitivity to antibacterial peptides present in the lungs of BALB/c mice. These data support the view that lipopolysaccharide acylation plays a important role in providing Gram-negative bacteria some resistance to structural and innate defenses and especially the antibacterial properties of detergents (e.g. bile) and cationic defensins.

Topics: Acylation; Animals; Anti-Bacterial Agents; Bacterial Capsules; Blood Bactericidal Activity; Defensins; Disease Models, Animal; Drug Resistance, Microbial; Humans; Klebsiella Infections; Klebsiella pneumoniae; Lipid A; Mice; Mice, Inbred BALB C; Phagocytosis; Pneumonia, Bacterial; Sepsis

Glucose analogues 5 and 9 of E5564 were synthesized, and their LPS-antagonistic activities were measured. The inhibitory activities (IC50) on LPS-induced TNFalpha production of these two compounds towards human whole blood cells were 0.06 and 0.83 nM, respectively. Inhibitory doses (ID50) of compounds 5 and 9 on TNFalpha production induced by coinjection of galactosamine and LPS in C3H/HeN mice in vivo were measured and were 0.55 and <0.20 mg/kg, respectively. And also C3H/HeN mice preinjected with compounds 5 and 9 were protected from lethality induced by coinjection of galactosamine and LPS; out of eight mice preinjected with 1 mg/kg of the compounds, one-six and three of eight mice were protected, respectively.

Topics: Animals; Escherichia coli; Glucose; Lipid A; Male; Mice; Molecular Structure; Sepsis; Tumor Necrosis Factor-alpha

E5564, a competitive lipid A antagonist, inhibits endotoxin-stimulated inflammation and is under study in patients with sepsis.. We tested whether clinically relevant variables, including the timing of treatment and the route of infection, influenced the effective dosing of E5564 in Escherichia coli-challenged rats.. All E5564 doses (0.3, 1.0, 2.0, and 3.0 mg/kg intravascular bolus followed by 10% of the bolus dose infused hourly for 24 h) administered 1 h before intravascular E. coli challenge similarly reduced the risk of death. Delaying the start of E5564 to 1 or 3 h after intravascular E. coli challenge significantly reduced the beneficial effect of the doses tested. However, increasing the dose of E5564 reversed some loss of efficacy for delayed treatment (P=.004, for increasing benefit with increasing dose at 1 h). During intrabronchial or intraperitoneal (extravascular) E. coli challenge, the pattern of effective E5564 dosing was the inverse of that for intravascular E. coli challenge (P=.001, for the interaction)--lower doses of E5564 were beneficial and higher doses were not (0.03, 0.3, 1.0, 2.0, and 3.0 mg/kg bolus followed by infusion) (P=.05, for decreasing benefit with increasing dose at 1 h).. These findings suggest that, for maximal clinical benefit, E5564 should be given early and that dosing should be adjusted upward for intravascular infection and downward for extravascular infection.

Topics: Animals; Blood Chemical Analysis; Blood Circulation; Colony Count, Microbial; Disease Models, Animal; Endotoxins; Escherichia coli Infections; Leukocyte Count; Lipid A; Lipopolysaccharides; Lung; Random Allocation; Rats; Rats, Sprague-Dawley; Sepsis; Survival Analysis; Time Factors; Tumor Necrosis Factor-alpha

Lipopolysaccharides (LPS), otherwise termed "endotoxins", are outer membrane constituents of Gram-negative bacteria. Lipopolysaccharides play a key role in the pathogenesis of "septic shock", a major cause of mortality in the critically ill patient. Therapeutic options aimed at limiting downstream systemic inflammatory processes by targeting lipopolysaccharide do not exist at the present time. We have defined the pharmacophore necessary for small molecules to specifically bind and neutralize LPS and, using animal models of sepsis, have shown that the sequestration of circulatory LPS by small molecules is a therapeutically viable strategy. In this paper, the interactions of a series of acylated homologated spermine compounds with LPS have been characterized. The optimal acyl chain length for effective sequestration of LPS was identified to be C(16) for the monoacyl compounds. The most promising of these compounds, 4e, binds LPS with an ED(50) of 1.37 muM. Nitric oxide production in murine J774A.1 cells, as well as TNF-alpha in human blood, is inhibited in a dose-dependent manner by 4e at concentrations orders of magnitude lower than toxic doses. Administration of 4e to d-galactosamine-sensitized mice challenged with supralethal doses of LPS provided significant protection against lethality. Potent antiendotoxic activity, low toxicity, and ease of synthesis render this class of compounds candidate endotoxin-sequestering agents of potential significant therapeutic value.

Topics: Amides; Animals; Cell Line; Cell Survival; Escherichia coli; Female; Hemolysis; Humans; In Vitro Techniques; Lipid A; Lipopolysaccharides; Mice; Nitric Oxide; Sepsis; Spermine; Structure-Activity Relationship; Surface Properties; Tumor Necrosis Factor-alpha

Topics: Anti-Infective Agents; Cyclopentanes; Drug Design; Endotoxins; Ligands; Lipid A; Sepsis; Structure-Activity Relationship

Topics: Forecasting; Humans; Lipid A; Lipopolysaccharides; Sepsis

Polymicrobial sepsis induced by cecal ligation and puncture (CLP) reproduces many of the pathophysiologic features of septic shock. In this study, we demonstrate that mRNA for a broad range of pro- and anti-inflammatory cytokine and chemokine genes are temporally regulated after CLP in the lung and liver. We also assessed whether prophylactic administration of monophosphoryl lipid A (MPL), a nontoxic derivative of lipopolysaccharide (LPS) that induces endotoxin tolerance and attenuates the sepsis syndrome in mice after CLP, would alter tissue-specific gene expression post-CLP. Levels of pulmonary interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), granulocyte colony-stimulating factor (G-CSF), IL-1 receptor antagonist (IL-1ra), and IL-10 mRNA, as well as hepatic IL-1beta, IL-6, gamma interferon (IFN-gamma), G-CSF, inducible nitric oxide synthase, and IL-10 mRNA, were reduced in MPL-pretreated mice after CLP compared to control mice. Chemokine mRNA expression was also profoundly mitigated in MPL-pretreated mice after CLP. Specifically, levels of pulmonary and hepatic macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, MIP-2, and monocyte chemoattractant protein-1 (MCP-1) mRNA, as well as hepatic IFN-gamma-inducible protein 10 and KC mRNA, were attenuated in MPL-pretreated mice after CLP. Attenuated levels of IL-6, TNF-alpha, MCP-1, MIP-1alpha, and MIP-2 in serum also were observed in MPL-pretreated mice after CLP. Diminished pulmonary chemokine mRNA production was associated with reduced neutrophil margination and pulmonary myeloperoxidase activity. These data suggest that prophylactic administration of MPL mitigates the sepsis syndrome by reducing chemokine production and the recruitment of inflammatory cells into tissues, thereby attenuating the production of proinflammatory cytokines.

Topics: Adjuvants, Immunologic; Animals; Cecum; Chemokines; Cytokines; Disease Models, Animal; Gene Expression Regulation; Immune Tolerance; Kinetics; Lipid A; Liver; Lung; Mice; Mice, Inbred C57BL; Neutrophils; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; RNA, Messenger; Sepsis

We developed 9H1.B11, an anti-idiotypic anti-deep core/lipid A (DCLA), murine monoclonal antibody (mAb) that mimics the conserved DCLA region of lipopolysaccharide (LPS). It recognizes an epitope in the variable region of an DCLA mAb, binds to the murine macrophage cell surface, and inhibits LPS-induced macrophage cytokine secretion. We hypothesized that (1) active immunization with mAb 9H1.B11 would be associated with the development of anti-DCLA antibodies and (2) immunization would protect against subsequent gram negative bacterial challenge. Mice were immunized for 8 weeks before intraperitoneal (ip) challenge with Escherichia coli O111:B4 bacteria. Control animals were immunized with an irrelevant IgM antibody 8133 (negative control) or with LPS derived from Salmonella minnesota Re bacteria (positive control). Sera from immunized mice were collected, and titers against the core region of LPS (Re) and against LPS derived from the infecting E. coli strain were determined. Mice immunized with mAb 9H1.B11 developed measurable titers against S. minnesota Re LPS but not against the challenge strain of E. coli. However, immunization with 9H1.B11 on S. minnesota Re LPS protected against subsequent infection due to E. coli O111:B4 (100% survival). The group of mice immunized with IgM 8133 exhibited only 25% survival. The development of an anti-S. minnesota Re LPS titer after immunization with 9H1.B11 provides further evidence that a portion of 9H1.B11 mimics the conserved DCLA region of LPS. We believe that this approach holds considerable promise and plan further studies to define the mechanism by which protective capacity occurs.

Topics: Animals; Antibodies, Anti-Idiotypic; Antibodies, Bacterial; Antibodies, Monoclonal; Epitope Mapping; Escherichia coli Infections; Female; Gram-Negative Bacteria; Lipid A; Lipopolysaccharides; Mice; Mice, Inbred BALB C; Sepsis

Topics: Animals; Clinical Trials as Topic; Humans; Lipid A; Lipoproteins, HDL; Nitric Oxide; Research; Sepsis; Tumor Necrosis Factor-alpha

A lipid A monoclonal antibody(mAb) was prepared and it was used to study its protective effect against burn sepsis. Wistar rats were inflicted with 30% TBSA third degress burn, and they were given LPS to mimic early sepsis after burn. The rats were divided randomly into burn with LPS, monoclonal antibody treatment, and control groups. The levels of endotoxin, tumor necrosis factor, light and electron microscopic studies of the morphological changes in the liver were studied. The results showed that the anti-lipid A monoclonal antibody demonstrated capacity to cross-react with several Gram-negative bacteria and their endotoxins. The mAb improved the survival rate of rats and decreased the levels of endotoxin and TNF as well as the liver damage significantly.

Topics: Animals; Antibodies, Monoclonal; Burns; Female; Lipid A; Male; Mice; Mice, Inbred BALB C; Random Allocation; Rats; Rats, Wistar; Sepsis

For developing monoclonal antibodies (MAb) that bound to lipid A of the LPS molecule, we established several hybridomas cell lines by fusion of SP2/0 and spleen cells from BALB/c mice immunized by J5 mutant strain of E. coli 0111:B4. Each MAb exhibited a high titer by ELISA assay. Six of MAb were of immunoglobulin G isotype and another one immunoglobulin M. All of these MAb demonstrated different capacity to cross-react with several gram-negative bacteria and their endotoxins. Among them, 9G6 MAb improved the survival rate of mice significantly when administered 2 hours before the challenge by pseudomonas A and E. coli. These findings suggest that MAb will probably be useful in the treatment of sepsis caused by a wide variety of gram-negative bacteria.

Topics: Animals; Antibodies, Bacterial; Antibodies, Monoclonal; Endotoxins; Escherichia coli; Female; Hybridomas; Lipid A; Mice; Mice, Inbred BALB C; Pseudomonas aeruginosa; Sepsis

The ability of monophosphoryl lipid A (MLA) to provide prophylactic protection against septic shock was evaluated in a mouse model of induced endotoxin hypersensitivity. Treatments of hypersensitized animals with low doses of MLA attenuated endotoxin lethality and endotoxin-mediated liver damage. These effects were related to the ability of MLA to suppress accumulation of TNF-alpha and IFN-gamma in the bloodstream of animals. MLA treatments had only a modest effect in suppressing the accumulation of nitrate in the bloodstream. This implied that MLA did not suppress induction of macrophage and hepatocyte nitric oxide synthetases that contribute to antimicrobial defense and protect against endotoxin-mediated liver damage. The MLA treatments did not appear to compromise inflammatory defenses against local infection since locally recruited leukocytes remained responsive to endotoxin after hypersensitivity had been attenuated. In agreement with these findings, other studies have shown that the induction of endotoxin tolerance by MLA parallels the induction of resistance of animals to lethal challenges with either Gram negative or Gram positive bacteria. As predicted from preclinical studies, human trials of the clinical form of MLA (MPL-immunostimulant) have confirmed that MLA could attenuate systemic responses to endotoxin in normal volunteers, including the attenuation of blood cytokine accumulation and attenuation of symptomatic responses.

Topics: Adjuvants, Immunologic; Animals; Disease Models, Animal; Female; Humans; Interferon-gamma; Lipid A; Lipopolysaccharides; Liver; Macrophages, Peritoneal; Mice; Mice, Inbred ICR; Nitric Acid; Sepsis; Shock, Septic; Tumor Necrosis Factor-alpha

SDZ MRL 953 (SDZ), a novel immunostimulatory lipid A analog, has been reported to have immunopharmacological activities similar to those of lipopolysaccharide (LPS) but to have little of the toxicity of LPS. We investigated the effects of pretreatment with SDZ on Escherichia coli endotoxin-induced acute lung injury in guinea pigs. Four experimental groups consisted of saline control (n = 16), SDZ (-12 h) plus LPS (2 mg/kg of SDZ per kg of body weight injected intravenously 12 h before intravenous injection of 2 mg of LPS per kg; n = 15), SDZ (-10 min) plus LPS (SDZ injected 10 min before LPS injection; n = 10), and LPS alone (n = 16). The animals were sacrificed, and lung tissue was sampled 4 h after LPS or saline infusion. Lung injury was assessed by measuring the wet weight-to-dry weight ratio and the level of 125I-labeled albumin accumulation in bronchoalveolar lavage fluid relative to that in plasma. In the SDZ (-12 h) plus LPS group, these two parameters of acute lung injury were decreased compared with those in the LPS alone group. However, they were not decreased in the SDZ (-10 min) plus LPS group. We conclude that SDZ attenuates endotoxin-induced acute lung injury when it is administered 12 h before LPS injection. The attenuating effects of SDZ are speculated to be due to down regulation of the response to endotoxin rather than to receptor blocking.

Topics: Adjuvants, Immunologic; Albumins; Animals; Bronchoalveolar Lavage Fluid; Endotoxins; Female; Guinea Pigs; Hemodynamics; Leukocyte Count; Lipid A; Lipopolysaccharides; Lung; Neutrophils; Respiratory Distress Syndrome; Sepsis; Survival Rate; Tumor Necrosis Factor-alpha; Water

Human peritoneal macrophages were exposed to increasing doses of LPS or a synthetic lipid A analogue (SDZ MRL 953) and production of the cytokines IL-1 beta, IL-6, TNF-alpha, and G-CSF was assessed at the protein and mRNA level. Cells were also prestimulated with low doses of LPS and SDZ MRL 953 to study their adaptation to a secondary challenge with high doses of LPS. The ability of macrophages to produce high levels of TNF-alpha and IL-6 after stimulation with LPS could be relieved almost completely by preincubating cells with low doses of LPS. Decreases of TNF-alpha and IL-6 production resulted from inhibition of gene transcription and/or changes in mRNA stability, as transcript levels of these cytokines were down-modulated by the process of LPS adaptation. Surprisingly, however, adapted cells were able to synthesize even larger quantities of G-CSF and IL-1 beta when exposed to a secondary LPS challenge. mRNA levels of the adapted cells remained unaltered for IL-1 beta, but were slightly increased for G-CSF as assessed by Northern blot analysis. High doses of the synthetic lipid A analogue SDZ MRL 953 were also able to adapt macrophages to a secondary LPS challenge by down-regulating TNF-alpha and IL-6 production, whereas priming secretion of G-CSF and IL-1 beta as well. We describe here the discordant adaptation of human peritoneal macrophages to a secondary LPS stimulus in vitro. These findings appear to have ramifications for the in vivo endotoxin response during inflammation and also Gram-negative septicemia.

Topics: Dinoprostone; Gene Expression; Granulocyte Colony-Stimulating Factor; Humans; Interleukin-1; Interleukin-6; Lipid A; Lipopolysaccharides; Macrophages, Peritoneal; RNA, Messenger; Sepsis; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Monophosphoryl lipid A (MLA), a substructure of bacterial lipopolysaccharide (LPS), is being developed as a prophylactic for sepsis and septic shock. In the present study it was shown that MLA induced a rapid accumulation of IFN-gamma in mice that correlated with an in vivo priming of macrophages. Primed macrophages could be induced in vitro to synthesize nitric oxide, a key mediator of macrophage cytotoxicity. Due to its rapid clearance, MLA was not present in circulation at the time when IFN-gamma accumulated, suggesting that MLA could not synergize with IFN-gamma to systemically activate macrophages in vivo. MLA treatment tolerized mice against the IFN-gamma response--ie., treatment of mice with MLA on day 1 blocked LPS from inducing IFN-gamma on days 2-4. The significance of these results in relation to MLA's ability to enhance non-specific resistance and block LPS lethality in animals is discussed.

Topics: Animals; Cells, Cultured; Female; Interferon-gamma; Lipid A; Lipopolysaccharides; Macrophage Activation; Macrophages; Mice; Mice, Inbred ICR; Nitrites; Salmonella; Sepsis; Shock, Septic

Lipid X, a monosaccharide precursor of lipid A, has been found to prevent death in animals given a lethal dose of endotoxin, but the mechanism of this protective effect is unknown. We previously reported that lipid X blocks endotoxin-induced priming of human neutrophils in a manner consistent with competitive inhibition. To determine the molecular requirements for this antiendotoxin activity, we studied several derivatives of lipid X using the neutrophil priming assay. Neutrophil priming was quantitated by measuring stimulated superoxide (O2-) release. The removal of either acyl group from lipid X or even the simple change of the amide to an ester linkage at C2 of the glucosamide ring resulted in a marked loss of antagonism. Monosaccharide analogues, structurally related to native lipid A by the presence of acyloxyacyl side chains, demonstrated marked inhibition of endotoxin-induced priming at low concentrations but an endotoxin-like, priming effect at high concentrations. The addition of a phosphate group at position 4 of the sugar moiety was the only modification studied so far that produced a pure antagonist with increased antiendotoxin activity. Demonstration of these structural requirements for the antiendotoxin activity of lipid A analogues supports the hypothesis that this effect may be mediated via specific cellular binding sites. Lipid X derivatives may be useful for studying the interaction of endotoxin with cells and their antiendotoxin activity may prove beneficial in the treatment of septicemia.

Topics: Bacterial Infections; Chemical Phenomena; Chemistry; Endotoxins; Glycolipids; Humans; In Vitro Techniques; Lipid A; Myristic Acids; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Sepsis; Superoxides; Trypan Blue

Nine patients with suspected gram-negative bacterial sepsis were studied to determine the safety, pharmacokinetics, and immunogenicity of XMMEN-0E5, a murine immunoglobulin M monoclonal antibody directed against the core lipid A region of bacterial endotoxin. Antibody was administered by single intravenous infusion of 1 to 4 h duration at doses ranging from 0.1 to 15 mg/kg. Five patients had positive blood cultures for gram-negative bacteria, one patient had Torulopsis septicemia, one patient had gram-negative bacterial meningitis, and two patients were culture negative. No evidence of antibody-mediated toxicity was observed at any dose level. The serum half-life of the antibody was approximately 10 h at doses of 0.1 to 7.5 mg/kg and approximately 18 h at a dose of 15 mg/kg. No apparent difference in clearance of antibody was observed between bacteremic and nonbacteremic patients. Human anti-mouse antibodies were detected in the sera of three evaluable patients that received doses equal to or greater than 2.0 mg/kg but not in patients that received lower doses of antibody. This study demonstrates that XMMEN-0E5 is well tolerated at doses from 0.1 to 15 mg/kg and may be immunogenic at doses of 2.0 mg/kg and above. Controlled trials to establish the efficacy of this antibody in the treatment of gram-negative bacteremia are indicated.

Topics: Adult; Aged; Antibodies, Monoclonal; Drug Evaluation; Female; Gram-Negative Bacteria; Half-Life; Humans; Lipid A; Male; Middle Aged; Sepsis

The serum titres of IgG and IgM antibodies to lipid A were measured in 24 children with chronic pyelonephritis (PN), 55 with recurrent lower urinary tract infections (LUTI), 13 with gram-negative sepsis (S), and in 50 control children using an enzyme-linked immunosorbent assay (ELISA). Children ranged in age from 1 month-17 years. Patients with PN were differentiated by the presence or absence of an acute infectious episode and/or vesico-ureteric reflux (VUR). During an acute episode in PN and LUTI, IgG titres were significantly higher than in controls, but only PN patients with an acute infectious episode also had significantly elevated IgM titres. Overall, children with LUTI showed a significantly lower frequency of detectable IgG lipid A antibodies (27%) than in PN (63%). In PN children with VUR not accompanied by an infectious episode, lipid A antibody was found at relatively low titres, while an episode not accompanied by VUR displayed significantly elevated IgG titres, and an episode accompanied by VUR showed elevation of both IgG and IgM anti-lipid A antibody titres.

Topics: Adolescent; Child; Child, Preschool; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunoglobulin G; Immunoglobulin M; Infant; Lipid A; Male; Pyelonephritis; Recurrence; Sepsis; Urinary Tract Infections; Vesico-Ureteral Reflux

Lipid A is the toxic component of endotoxin in gram-negative bacteria. Antibodies to lipid A are not usually found in healthy persons (or only at a low titer) without a corresponding history of infection. Even gram-negative septicemia is found to be accompanied by only low titers. A completely different situation is seen in patients with chronic or recurrent infections due to Enterobacteriaceae and other gram-negative bacteria. Here it is notable that the antibody titer varies with the type of disorder (e. g. cystitis and pyelonephritis). A severe would infection, e. g. due to Pseudomonas aeruginosa, also leads to measurable lipid A antibody titers. Varying antibody titers can be observed in cystic fibrosis, Crohn's disease, and severe surgical infections. One can conclude that a significantly elevated antibody titer develops during an extensive tissue involvement of long duration and indeed is caused by tissue inhibition by endotoxin. Based on clinical experience, it can be assumed that lipid A antibodies present in the body have a protective effect in septic shock.

Topics: Adolescent; Adult; Antitoxins; Bacterial Infections; Child; Enterobacteriaceae Infections; Humans; Immunoglobulin G; Lipid A; Pyelonephritis; Sepsis; Urinary Tract Infections; Wound Infection

To study the role of antibodies in promoting survival during gram-negative bacterial sepsis, we have developed several murine monoclonal antibodies (MAbs). One MAb (5B10) reacted in an enzyme-linked immunosorbent assay with only a single organism (Escherichia coli 0111:B4), while the other (8A1) reacted to all gram-negative whole-cell and lipopolysaccharide (LPS) antigens examined. Either 5B10 MAb, 8A1 MAb, or sterile saline solution was administered intravenously to outbred male Swiss-Webster mice immediately before one of three challenges: (1) viable bacteria intravenously, (2) viable bacteria with hemoglobin intraperitoneally, or (3) intravenous actinomycin D plus LPS. 5B10 MAb provided significant protection against either an E. coli 0111:B4 bacterial or LPS challenge but not against any other organism or type of LPS. 8A1 MAb provided protection against several challenge bacteria (intravenously or intraperitoneally) and against all types of LPS studied except Pseudomonas aeruginosa LPS. A higher dose (2 mg) of cross-reactive antibody (8A1 MAb) was required to produce protection when compared with the type-specific protection produced with 5B10 MAb (0.1 mg). Although ideal antibody therapy would consist of directing a specific MAb against a single microorganism, the acute nature of the disease process and time required to prepare reagents may preclude the use of type-specific MAbs. We believe that the cross-reactive and cross-protective capacity of 8A1 MAb or a similar MAb may be useful in averting the lethal effects of clinical gram-negative bacterial sepsis and warrants testing in the clinical setting.

Topics: Animals; Antibodies, Monoclonal; Antibody Specificity; Cross Reactions; Disease Models, Animal; Endotoxins; Enzyme-Linked Immunosorbent Assay; Escherichia coli Infections; Lipid A; Lipopolysaccharides; Male; Mice; Mice, Inbred BALB C; Peritonitis; Sepsis

The role of lipopolysaccharide (LPS) in the virulence of Pseudomonas aeruginosa was studied. The virulence of several P. aeruginosa strains for burned mice was found to be directly related to the dispersion of LPS into either the phenol or the water phase after extraction. Virulence decreased as the proportion of LPS recovered from the phenol phase increased. No similar correlation was observed when several other strain characteristics were investigated. This phenomenon was studied in greater detail by using the "smooth"-specific phage E79 to select mutants altered in LPS structure. One such mutant, PA220-R2, was extensively characterized. LPS isolated from PA220-R2 was found to be completely deficient in high-molecular-weight polysaccharide material. This alteration rendered the strain serum sensitive and dramatically changed the reaction with O-specific typing sera and sensitivity to typing phages. However, motility, toxin A and elastase production, and 22 metabolic functions remained unchanged. PA220-R2 was found to be comparatively nonvirulent, with a 50% lethal dose more than 1,000-fold higher than that of its parent for burned mice. This was due to the inability of PA220-R2 to establish an infection in burned skin.

Topics: Animals; Burns; Endopeptidases; Galactosamine; Hexosamines; Lipid A; Lipopolysaccharides; Mice; Mutation; Pancreatic Elastase; Pseudomonas aeruginosa; Pseudomonas Infections; Sepsis; Serine Endopeptidases; Serotyping; Virulence

Topics: Animals; Humans; Lipid A; Lipopolysaccharides; Salmonella Infections; Sepsis

Anti-lipid-A, anti-endotoxin, antibodies have been measured by a passive haemolysis test using antigen from an E. coli Re mutant. Titres in the normal population are low but do rise in situations in which there has been gram-negative sepsis. Absence of raised titres in other situations has profound implications.

Topics: Animals; Antibodies, Bacterial; Child, Preschool; Hemolysis; Humans; Lipid A; Lipopolysaccharides; Sepsis; Sheep

Topics: Antibodies; Humans; Lipid A; Lipopolysaccharides; Sepsis; Shock, Septic