lipid-a and Pseudomonas-Infections

Septic shock is caused by Gram-negative bacterial infection. Lipopolysaccharide (LPS) is the bioactive molecule present on the outer membrane of the Gram-negative bacteria. It is generally thought that LPS interacts with sensors on the host cell membrane to activate the intracellular signaling pathway resulting in the overproduction of cytokines such as TNF-alpha. This causes inflammation and ultimately, septic shock. Lipid A is the pharmacophore of the LPS molecule. Thus, developing bio-molecules which are capable of binding LPS at high affinity, especially to the lipid A moiety is an efficient way to neutralize the LPS toxicity. Factor C, a serine protease in the horseshoe crab ameobocytes, is sensitive to trace levels of LPS. We have derived Sushi peptides from the LPS-binding domains of Factor C. Our earlier study showed that the Sushi peptides inhibit LPS-induced septic shock in mice. Here, we demonstrate that the molecular interaction between LPS and Sushi 1 peptide is supported by the hydrophobic interaction between the lipid tail of LPS and Sushi 1 peptide. Furthermore, in the presence of LPS, the peptide transitions from a random structure into an alpha-helical conformation and it disrupts LPS aggregates, hence, neutralizing the LPS toxicity.

Topics: Animals; Arthropod Proteins; Binding Sites; Enzyme Precursors; Gram-Negative Bacterial Infections; Humans; Lipid A; Peptides; Protein Binding; Protein Structure, Secondary; Pseudomonas; Pseudomonas Infections; Serine Endopeptidases; Shock, Septic; Structure-Activity Relationship

Topics: Acylation; Anti-Bacterial Agents; Bacterial Proteins; Carrier Proteins; Cystic Fibrosis; Drug Resistance, Microbial; Escherichia coli Proteins; Glycosaminoglycans; Humans; Lipid A; Lipopolysaccharides; Lung; Membrane Transport Proteins; Peptides; Pseudomonas aeruginosa; Pseudomonas Infections; RNA-Binding Proteins; Symporters; Virulence

Pseudomonas aeruginosa is one of the most important opportunistic bacterial pathogens in humans and animals. This organism is ubiquitous and has high intrinsic resistance to antibiotics due to the low permeability of the outer membrane and the presence of numerous multiple drug efflux pumps. Various cell-associated and secreted antigens of P. aeruginosa have been the subject of vaccine development. Among pseudomonas antigens, the mucoid substance, which is an extracellular slime consisting predominantly of alginate, was found to be heterogenous in terms of size and immunogenicity. High molecular mass alginate components (30-300 kDa) appear to contain conserved epitopes while lower molecular mass alginate components (10-30 kDa) possess conserved epitopes in addition to unique epitopes. Surface-exposed antigens including O-antigens (O-specific polysaccharide of LPS) or H-antigens (flagellar antigens) have been used for serotyping due to their highly immunogenic nature. Chemical structures of repeating units of O-specific polysaccharides have been elucidated and these data allowed the identification of 31 chemotypes of P. aeruginosa. Conserved epitopes among all serotypes of P. aeruginosa are located in the core oligosaccharide and the lipid A region of LPS and immunogens containing these epitopes induce cross-protective immunity in mice against different P. aeruginosa immunotypes. To examine the protective properties of OM proteins, a vaccine containing P. aeruginosa OM proteins of molecular masses ranging from 20 to 100 kDa has been used in pre-clinical and clinical trials. This vaccine was efficacious in animal models against P. aeruginosa challenge and induced high levels of specific antibodies in human volunteers. Plasma from human volunteers containing anti-P. aeruginosa antibodies provided passive protection and helped the recovery of 87% of patients with severe forms of P. aeruginosa infection. Vaccines prepared from P. aeruginosa ribosomes induced protective immunity in mice, but the efficacy of ribosomal vaccines in humans is not yet known. A number of recent studies indicated the potential of some P. aeruginosa antigens that deserve attention as new vaccine candidates. The outer core of LPS was implicated to be a ligand for binding of P. aeruginosa to airway and ocular epithelial cells of animals. However, heterogeneity exists in this outer core region among different serotypes. Epitopes in the inner core are highly conserved and it has been demon

Topics: Alginates; Animals; Antibodies, Bacterial; Antigens, Bacterial; Bacterial Outer Membrane Proteins; Bacterial Proteins; Bacterial Vaccines; Carbohydrate Sequence; Cell Membrane; Cross Reactions; Epitopes; Fimbriae, Bacterial; Flagella; Humans; Immunization, Passive; Lipid A; Lipopolysaccharides; Mice; Molecular Sequence Data; O Antigens; Polysaccharides, Bacterial; Pseudomonas aeruginosa; Pseudomonas Infections; Virulence

Colistin represents the last-line treatment option against many multidrug-resistant Gram-negative pathogens. Several lines of evidence indicate that aminoarabinosylation of the lipid A moiety of lipopolysaccharide (LPS) is an essential step for the development of colistin resistance in Pseudomonas aeruginosa. However, whether it is sufficient to confer resistance in this bacterium remains unclear. The aim of this work was to investigate the specific contribution of lipid A aminoarabinosylation to colistin resistance in P. aeruginosa and evaluate the effect of this resistance mechanism on bacterial fitness. Recombinant strains constitutively expressing the enzymes for lipid A aminoarabinosylation were generated in a small collection of reference and clinical isolates and verified by quantitative reverse transcription polymerase chain reaction (qRT-PCR), lipid A extraction and mass spectrometry. The effect of aminoarabinosylated lipid A on colistin resistance was found to be strain- and culture condition-dependent. Higher levels of resistance were generally obtained in the presence of divalent cations, which appear to be important for aminoarabinosylation-mediated colistin resistance. High colistin resistance was also observed for most strains in human serum and in artificial sputum medium, which should partly mimic growth conditions during infection. The results of growth, biofilm, cell envelope integrity and Galleria mellonella infection assays indicate that lipid A aminoarabinosylation does not cause relevant fitness costs in P. aeruginosa.

Topics: Animals; Anti-Bacterial Agents; Arabinose; Biofilms; Colistin; Disk Diffusion Antimicrobial Tests; Drug Resistance, Multiple, Bacterial; Humans; Lipid A; Moths; Pseudomonas aeruginosa; Pseudomonas Infections

Monophosphoryl lipid A (MPLA) is a TLR4 agonist that has potent immunomodulatory properties and modulates innate immune function to improve host resistance to infection with common nosocomial pathogens in mice. The goal of this study was to assess the safety and efficacy of MPLA in a sheep model of burn injury and Pseudomonas aeruginosa pneumonia. The sheep provides a favorable model for preclinical testing as their response to TLR4 agonists closely mimics that of humans.. Twelve chronically instrumented adult female Merino sheep received 20% total body surface area, third-degree cutaneous burn under anesthesia and analgesia. At 24 h after burn, sheep were randomly allocated to receive: MPLA (2.5 μg/kg i.v., n = 6), or vehicle (i.v., n = 6). At 24 h after MPLA or vehicle treatment, Pseudomonas aeruginosa pneumonia was induced. Sheep were mechanically ventilated, fluid resuscitated and cardiopulmonary variables were monitored for 24 h after induction of pneumonia. Cytokine production, vascular barrier function, and lung bacterial burden were also measured.. MPLA infusion induced small and transient alterations in core body temperature, heart rate, pulmonary artery pressure, and pulmonary vascular resistance. Pulmonary mechanics were not altered. Vehicle-treated sheep developed severe acute lung injury during Pseudomonas aeruginosa pneumonia, which was attenuated by MPLA as indicated by improved PaO2/FiO2 ratio, oxygenation index, and shunt fraction. Sheep treated with MPLA also exhibited less vascular leak, lower blood lactate levels, and lower modified organ injury score. MPLA treatment attenuated systemic cytokine production and decreased lung bacterial burden.. MPLA was well tolerated in burned sheep and attenuated development of acute lung injury, lactatemia, cytokinemia, vascular leak, and hemodynamic changes caused by Pseudomonas aeruginosa pneumonia.

Topics: Adjuvants, Immunologic; Animals; Burns; Disease Models, Animal; Female; Lipid A; Multiple Organ Failure; Pneumonia, Bacterial; Pseudomonas aeruginosa; Pseudomonas Infections; Sheep

The goal was to investigate the mechanisms of colistin resistance and heteroresistance in

Topics: Anti-Bacterial Agents; Bacterial Proteins; China; Colistin; Drug Resistance, Multiple, Bacterial; Electrophoresis, Gel, Pulsed-Field; Gene Expression Regulation, Bacterial; Humans; Lipid A; Microbial Sensitivity Tests; Multilocus Sequence Typing; Mutation; Pseudomonas aeruginosa; Pseudomonas Infections; Repressor Proteins; Transcription Factors

Lipid A aminoarabinosylation is invariably associated with colistin resistance in

Topics: Anti-Bacterial Agents; Bacterial Proteins; Colistin; Drug Resistance, Bacterial; Drug Resistance, Multiple, Bacterial; Humans; Lipid A; Microbial Sensitivity Tests; Pseudomonas aeruginosa; Pseudomonas Infections

Lipopolysaccharides (LPS) are complex glycolipids forming the outside layer of Gram-negative bacteria. Their hydrophobic and heterogeneous nature greatly hampers their structural study in an environment similar to the bacterial surface. We have studied LPS purified from E. coli and pathogenic P. aeruginosa with long O-antigen polysaccharides assembled in solution as vesicles or elongated micelles. Solid-state NMR with magic-angle spinning permitted the identification of NMR signals arising from regions with different flexibilities in the LPS, from the lipid components to the O-antigen polysaccharides. Atomic scale data on the LPS enabled the study of the interaction of gentamicin antibiotic bound to P. aeruginosa LPS, for which we could confirm that a specific oligosaccharide is involved in the antibiotic binding. The possibility to study LPS alone and bound to a ligand when it is assembled in membrane-like structures opens great prospects for the investigation of proteins and antibiotics that specifically target such an important molecule at the surface of Gram-negative bacteria.

Topics: Escherichia coli; Escherichia coli Infections; Humans; Lipid A; Lipopolysaccharides; Magnetic Resonance Spectroscopy; O Antigens; Oligosaccharides; Pseudomonas aeruginosa; Pseudomonas Infections

The partial structure and immunology of the lipopolysaccharide (LPS) of Pseudomonas stutzeri KMM 226, a bacterium isolated from a seawater sample collected at a depth of 2000 m, was characterised. The O-polysaccharide was built up of disaccharide repeating units constituted by L-Rhap and D-GlcpNAc: →2)-α-L-Rhap-(1→3)-α-D-GlcpNAc-(1→. The structural analysis of the lipid A showed a mixture of different species. The major species were hexa-acylated and penta-acylated lipids A, bearing the 12:0(3-OH) in amide linkage and 10:0(3-OH) in ester linkage, while the secondary fatty acids were present only as 12:0. The presence of 12:0(2-OH) was not detected. The immunology experiments demonstrated that P. stutzeri KMM 226 LPS displayed a low ability to induce TNF-α, IL-1β, IL-6, IL-8 and IL-10 cytokine production and acted as an antagonist of hexa-acylated Escherichia coli LPS in human blood in vitro.

Topics: Cytokines; Humans; Lipid A; Lipopolysaccharides; Magnetic Resonance Spectroscopy; O Antigens; Pseudomonas Infections; Pseudomonas stutzeri; Seawater; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Water Microbiology

The magnitude of the LPS-elicited cytokine response is commonly used to assess immune function in critically ill patients. A suppressed response, known as endotoxin tolerance, is associated with worse outcomes, yet endotoxin tolerance-inducing TLR4 ligands are known to protect animals from infection. Thus, it remains unknown whether the magnitude of the LPS-elicited cytokine response provides an accurate assessment of antimicrobial immunity. To address this, the ability of diverse TLR ligands to modify the LPS-elicited cytokine response and resistance to infection were assessed. Priming of mice with LPS, monophosphoryl lipid A (MPLA), or poly(I:C) significantly reduced plasma LPS-elicited proinflammatory cytokines, reflecting endotoxin tolerance, whereas CpG-ODN-primed mice showed augmented cytokine production. In contrast, LPS, MPLA, and CpG-ODN, but not poly(I:C), improved the host response to a

Topics: Animals; Cytokines; Disease Models, Animal; Flow Cytometry; Ligands; Lipid A; Lipopolysaccharides; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Poly I-C; Pseudomonas aeruginosa; Pseudomonas Infections; Toll-Like Receptors

Infection is the leading cause of death in severely burned patients that survive the acute phase of injury. Neutrophils are the first line of defense against infections, but hospitalized burn patients frequently cannot mount an appropriate innate response to infection. Thus, immune therapeutic approaches aimed at improving neutrophil functions after burn injury may be beneficial. Prophylactic treatment with the TLR4 agonist monophosphoryl lipid A is known to augment resistance to infection by enhancing neutrophil recruitment and facilitating bacterial clearance. This study aimed to define mechanisms by which monophosphoryl lipid A treatment improves bacterial clearance and survival in a model of burn-wound sepsis. Burn-injured mice were treated with monophosphoryl lipid A or vehicle, and neutrophil mobilization was evaluated in the presence or absence of Pseudomonas aeruginosa infection. Monophosphoryl lipid A treatment induced significant mobilization of neutrophils from the bone marrow into the blood and sites of infection. Neutrophil mobilization was associated with decreased bone marrow neutrophil CXCR4 expression and increased plasma G-CSF concentrations. Neutralization of G-CSF before monophosphoryl lipid A administration blocked monophosphoryl lipid A-induced expansion of bone marrow myeloid progenitors and mobilization of neutrophils into the blood and their recruitment to the site of infection. G-CSF neutralization ablated the enhanced bacterial clearance and survival benefit endowed by monophosphoryl lipid A in burn-wound-infected mice. Our findings provide convincing evidence that monophosphoryl lipid A-induced G-CSF facilitates early expansion, mobilization, and recruitment of neutrophils to the site of infection after burn injury, allowing for a robust immune response to infection.

Topics: Animals; Burns; Granulocyte Colony-Stimulating Factor; Lipid A; Mice; Mice, Inbred BALB C; Neutrophil Infiltration; Neutrophils; Pseudomonas aeruginosa; Pseudomonas Infections; Receptors, CXCR4

Pseudomonas aeruginosa (PA) infection in cystic fibrosis (CF) lung disease causes airway neutrophilia and hyperinflammation without effective bacterial clearance. We evaluated the immunostimulatory activities of lipid A, the membrane anchor of LPS, isolated from mutants of PA that synthesize structural variants, present in the airways of patients with CF, to determine if they correlate with disease severity and progression. In a subset of patients with a severe late stage of CF disease, a unique hepta-acylated lipid A, hepta-1855, is synthesized. In primary human cell cultures, we found that hepta-1855 functioned as a potent TLR4 agonist by priming neutrophil respiratory burst and stimulating strong IL-8 from monocytes and neutrophils. hepta-1855 also had a potent survival effect on neutrophils. However, it was less efficient in stimulating neutrophil granule exocytosis and also less potent in triggering proinflammatory TNF-α response from monocytes. In PA isolates that do not synthesize hepta-1855, a distinct CF-specific adaptation favors synthesis of a penta-1447 and hexa-1685 LPS mixture. We found that penta-1447 lacked immunostimulatory activity but interfered with inflammatory IL-8 synthesis in response to hexa-1685. Together, these observations suggest a potential contribution of hepta-1855 to maintenance of the inflammatory burden in late-stage CF by recruiting neutrophils via IL-8 and promoting their survival, an effect presumably amplified by the absence of penta-1447. Moreover, the relative inefficiency of hepta-1855 in triggering neutrophil degranulation may partly explain the persistence of PA in CF disease, despite extensive airway neutrophilia.

Topics: Acylation; Cells, Cultured; Chronic Disease; Cystic Fibrosis; Disease Progression; Exocytosis; HEK293 Cells; Humans; Lipid A; Lipopolysaccharides; Neutrophil Activation; Opportunistic Infections; Pneumonia, Bacterial; Pseudomonas aeruginosa; Pseudomonas Infections; Respiratory Burst; Structure-Activity Relationship; Toll-Like Receptor 4

Monophosphoryl lipid A (MPLA) is a lipopolysaccharides (LPS) derivative associated with neutrophil-dependent anti-inflammatory outcomes in animal models of sepsis. Little is known about the effect of MPLA on neutrophil function. This study sought to test the hypothesis that MPLA would reduce release of cytotoxic mediators from neutrophils without impairing bacterial clearance. Neutrophils were isolated from whole blood of healthy volunteers. The effects of MPLA and LPS on autologous serum-opsonised Pseudomonas aeruginosa killing by neutrophils and phagocytosis of autologous serum-opsonised zymosan were examined. Neutrophil oxidative burst, chemotaxis, enzyme and cytokine release as well as Toll-like receptor 4 (TLR4) expression were assessed following exposure to LPS or MPLA. LPS, but not MPLA, induced significant release of superoxide and myeloperoxidase from neutrophils. However, MPLA did not impair neutrophil capacity to ingest microbial particles and kill P. aeruginosa efficiently. MPLA was directly chemotactic for neutrophils, involving TLR4, p38 mitogen-activated protein kinase and tyrosine and alkaline phosphatases. LPS, but not MPLA, impaired N-formyl-methionyl-leucyl phenylalanine-directed migration of neutrophils, increased surface expression of TLR4, increased interleukin-8 release and strongly activated the myeloid differentiation primary response 88 pathway. Phosphoinositide 3-kinase inhibition significantly augmented IL-8 release from MPLA-treated neutrophils. The addition of MPLA to LPS-preincubated neutrophils led to a significant reduction in LPS-mediated superoxide release and TLR4 surface expression. Collectively, these findings suggest that MPLA directs efficient chemotaxis and bacterial killing in human neutrophils without inducing extracellular release of cytotoxic mediators and suggest that MPLA warrants further attention as a potential therapeutic in human sepsis.

Topics: Alkaline Phosphatase; Humans; Interleukin-8; Lipid A; Lipopolysaccharides; Myeloid Differentiation Factor 88; Neutrophils; p38 Mitogen-Activated Protein Kinases; Phagocytosis; Phosphatidylinositol 3-Kinases; Protein Tyrosine Phosphatases; Pseudomonas aeruginosa; Pseudomonas Infections; Signal Transduction; Superoxides; Toll-Like Receptor 4

Topics: Humans; Lipid A; Neutrophils; Pseudomonas aeruginosa; Pseudomonas Infections

Pseudomonas aeruginosa can develop resistance to polymyxin as a consequence of mutations in the PhoPQ regulatory system, mediated by covalent lipid A modification. Transposon mutagenesis of a polymyxin-resistant phoQ mutant defined 41 novel loci required for resistance, including two regulatory systems, ColRS and CprRS. Deletion of the colRS genes, individually or in tandem, abrogated the polymyxin resistance of a ΔphoQ mutant, as did individual or tandem deletion of cprRS. Individual deletion of colR or colS in a ΔphoQ mutant also suppressed 4-amino-L-arabinose addition to lipid A, consistent with the known role of this modification in polymyxin resistance. Surprisingly, tandem deletion of colRS or cprRS in the ΔphoQ mutant or individual deletion of cprR or cprS failed to suppress 4-amino-L-arabinose addition to lipid A, indicating that this modification alone is not sufficient for PhoPQ-mediated polymyxin resistance in P. aeruginosa. Episomal expression of colRS or cprRS in tandem or of cprR individually complemented the Pm resistance phenotype in the ΔphoQ mutant, while episomal expression of colR, colS, or cprS individually did not. Highly polymyxin-resistant phoQ mutants of P. aeruginosa isolated from polymyxin-treated cystic fibrosis patients harbored mutant alleles of colRS and cprS; when expressed in a ΔphoQ background, these mutant alleles enhanced polymyxin resistance. These results define ColRS and CprRS as two-component systems regulating polymyxin resistance in P. aeruginosa, indicate that addition of 4-amino-L-arabinose to lipid A is not the only PhoPQ-regulated biochemical mechanism required for resistance, and demonstrate that colRS and cprS mutations can contribute to high-level clinical resistance.

Topics: Anti-Bacterial Agents; Arabinose; Bacterial Proteins; Cystic Fibrosis; DNA Transposable Elements; Drug Resistance, Bacterial; Gene Deletion; Gene Expression Regulation, Bacterial; Genes, Regulator; Genetic Complementation Test; Genetic Loci; Humans; Lipid A; Mutation; Plasmids; Polymyxins; Pseudomonas aeruginosa; Pseudomonas Infections

Bacteria can naturally secrete outer membrane vesicles (OMVs) as pathogenic factors, while these vesicles may also serve as immunologic regulators if appropriately prepared. However, it is largely unknown whether Pseudomonas aeruginosa OMVs can activate inflammatory responses and whether immunization with OMVs can provide immune protection against subsequent infection. We purified and identified OMVs, which were then used to infect lung epithelial cells in vitro as well as C57BL/6J mice to investigate the immune response and the underlying signaling pathway. The results showed that OMVs generated from P. aeruginosa wild-type strain PAO1 were more cytotoxic to alveolar epithelial cells than those from quorum-sensing (QS)-deficient strain PAO1-ΔlasR. The levels of Toll-like receptor 4 (TLR4) and proinflammatory cytokines, including interleukin-1β (IL-1β) and IL-6, increased following OMV infection. Compared with lipopolysaccharide (LPS), lysed OMVs in which the membrane structures were broken induced a weak immune response. Furthermore, expression levels of TLR4-mediated responders (i.e., cytokines) were markedly downregulated by the TLR4 inhibitor E5564. Active immunization with OMVs or passive transfer of sera with a high cytokine quantity acquired from OMV-immunized mice could protect healthy mice against subsequent lethal PAO1 challenges (1.5 × 10(11) CFU). Collectively, these findings indicate that naturally secreted P. aeruginosa OMVs may trigger significant inflammatory responses via the TLR4 signaling pathway and protect mice against pseudomonal lung infection.

Topics: Animals; Bacterial Outer Membrane Proteins; Cell Line; Cytoplasmic Vesicles; Epithelial Cells; Humans; Immunization; Inflammation; Interleukin-1beta; Interleukin-6; Lipid A; Lipopolysaccharides; Lung; Mice; Mice, Inbred C57BL; Pseudomonas aeruginosa; Pseudomonas Infections; Pseudomonas Vaccines; Pulmonary Alveoli; Respiratory Mucosa; Signal Transduction; Toll-Like Receptor 4; Vaccination

Monophosphoryl lipid A (MPLA) is a Toll-like receptor 4 (TLR4) agonist that is currently used as a vaccine adjuvant in humans. In this study, we evaluated the effect of MPLA treatment on the innate immune response to systemic bacterial infections in mice. Mice treated with MPLA after burn injury showed improved survival and less local and systemic dissemination of bacteria in a model of Pseudomonas aeruginosa burn wound infection. Prophylactic treatment with MPLA significantly enhanced bacterial clearance at the site of infection and reduced systemic dissemination of bacteria despite causing attenuation of proinflammatory cytokine production during acute intra-abdominal infection caused by cecal ligation and puncture. Administration of MPLA at 1 h after CLP also improved bacterial clearance but did not alter cytokine production. MPLA treatment increased the numbers of granulocytes, double-positive myeloid cells, and macrophages at sites of infection and increased the percentage and total numbers of myeloid cells mediating phagocytosis of bacteria. Depletion of Ly6G(+) neutrophils, but not macrophages, eliminated the ability of MPLA treatment to improve bacterial clearance. The immunomodulatory effects of MPLA were absent in TLR4-deficient mice. In conclusion, these studies show that MPLA treatment significantly augments the innate immune response to bacterial infection by enhancing bacterial clearance despite the attenuation of proinflammatory cytokine production. The enhanced bacterial clearance is mediated, in part, by increased numbers of myeloid cells with effective phagocytic functions at sites of infection and is TLR4 dependent.

Topics: Animals; Burns; Cytokines; Female; Immunity, Innate; Lipid A; Lymphocyte Count; Macrophages; Male; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Neutrophils; Pseudomonas aeruginosa; Pseudomonas Infections; Signal Transduction; Toll-Like Receptor 4; Wound Infection

Pseudomonas aeruginosa can develop resistance to polymyxin and other cationic antimicrobial peptides. Previous work has shown that mutations in the PmrAB and PhoPQ regulatory systems can confer low to moderate levels of polymyxin resistance (MICs of 8 to 64 mg/liter) in laboratory and clinical strains of this organism. To explore the role of PhoPQ in high-level clinical polymyxin resistance, P. aeruginosa strains with colistin MICs > 512 mg/liter that had been isolated from cystic fibrosis patients treated with inhaled colistin (polymyxin E) were analyzed. Probable loss-of-function phoQ alleles found in these cystic fibrosis strains conferred resistance to polymyxin. Partial and complete suppressor mutations in phoP were identified in some cystic fibrosis strains with resistance-conferring phoQ mutations, suggesting that additional loci can be involved in polymyxin resistance in P. aeruginosa. Disruption of chromosomal phoQ in the presence of an intact phoP allele stimulated 4-amino-l-arabinose addition to lipid A and induced transcription from the promoter of the pmrH (arnB) operon, consistent with the known role of this lipid A modification in polymyxin resistance. These results indicate that phoQ loss-of-function mutations can contribute to high-level polymyxin resistance in clinical strains of P. aeruginosa.

Topics: Anti-Bacterial Agents; Bacterial Proteins; Colistin; Cystic Fibrosis; Drug Resistance, Bacterial; Female; Humans; Lipid A; Male; Microbial Sensitivity Tests; Mutation; Polymyxins; Pseudomonas aeruginosa; Pseudomonas Infections

New structural amphiphiles 2a and 2b bind the diphosphate lipid A anion and show potential as lead compounds for the development of novel antibacterial agents.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Anions; Anti-Bacterial Agents; Erythrocytes; Gram-Negative Bacteria; Humans; Lipid A; Microbial Sensitivity Tests; Models, Molecular; Pseudomonas aeruginosa; Pseudomonas Infections; Surface-Active Agents

Pseudomonas aeruginosa (PA) is a ubiquitous environmental Gram-negative bacterium found in soil and water. This opportunistic pathogen can cause infections in individuals with impaired phagocytic function, such as those with burns, exposure to chemotherapy, or cystic fibrosis (CF). PA infects the lungs of most individuals with CF, and is associated with severe progressive pulmonary disease that is the major cause of premature death in this disorder. The specific adaptations of PA to the CF airway responsible for bacterial persistence and antibiotic tolerance are not completely understood but may include increased alginate production (i.e., mucoid phenotype), biofilm formation, and specific lipid A modifications. During adaptation to the CF airway, PA synthesizes a variety of lipid A structures that alter host innate immune responses and promote bacterial persistence and chronic infection. The synthesis of specific lipid A structures is attributable to bacterial enzymes that: (1) remove the 3OH-C10:0 acyl chain from the 3-position (PagL); (2) add a C16:0 acyl chain to the 3OH-C10:0 chain at the 3'-position (PagP); (3) add C12:0 and 2OH-C12:0 acyl chains to the 3OH-C12:0 chains at the 2- and 2'-positions (HtrB and LpxO); and (4) add aminoarabinose to phosphate groups at the 1- and 4'-positions (PmrH, PmrF, PmrI, PmrJ, PmrK, and PmrE). These lipid A modifications represent an essential aspect of PA adaptation to the CF airway.

Topics: Adult; Antimicrobial Cationic Peptides; Carbohydrate Conformation; Carbohydrate Sequence; Child; Cystic Fibrosis; Humans; Inflammation; Lipid A; Lipopolysaccharides; Molecular Sequence Data; Molecular Structure; Pseudomonas aeruginosa; Pseudomonas Infections

Pseudomonas aeruginosa can establish life-long airways chronic infection in patients with cystic fibrosis (CF) with pathogenic variants distinguished from initially acquired strain. Here, we analysed chemical and biological activity of P. aeruginosa Pathogen-Associated Molecular Patterns (PAMPs) in clonal strains, including mucoid and non-mucoid phenotypes, isolated during a period of up to 7.5 years from a CF patient. Chemical structure by MS spectrometry defined lipopolysaccharide (LPS) lipid A and peptidoglycan (PGN) muropeptides with specific structural modifications temporally associated with CF lung infection. Gene sequence analysis revealed novel mutation in pagL, which supported lipid A changes. Both LPS and PGN had different potencies when activating host innate immunity via binding TLR4 and Nod1. Significantly higher NF-kB activation, IL-8 expression and production were detected in HEK293hTLR4/MD2-CD14 and HEK293hNod1 after stimulation with LPS and PGN respectively, purified from early P. aeruginosa strain as compared to late strains. Similar results were obtained in macrophages-like cells THP-1, epithelial cells of CF origin IB3-1 and their isogenic cells C38, corrected by insertion of cystic fibrosis transmembrane conductance regulator (CFTR). In murine model, altered LPS structure of P. aeruginosa late strains induces lower leukocyte recruitment in bronchoalveolar lavage and MIP-2, KC and IL-1beta cytokine levels in lung homogenates when compared with early strain. Histopathological analysis of lung tissue sections confirmed differences between LPS from early and late P. aeruginosa. Finally, in this study for the first time we unveil how P. aeruginosa has evolved the capacity to evade immune system detection, thus promoting survival and establishing favourable conditions for chronic persistence. Our findings provide relevant information with respect to chronic infections in CF.

Topics: Animals; Cell Line; Cell Movement; Chronic Disease; Colony Count, Microbial; Cystic Fibrosis; Cytokines; Humans; Immunity, Innate; Inflammation; Leukocytes; Lipid A; Lung; Mice; Nod1 Signaling Adaptor Protein; Peptides; Peptidoglycan; Pseudomonas aeruginosa; Pseudomonas Infections

Three structural features of lipid A (addition of palmitate [C16 fatty acid], addition of aminoarabinose [positively charged amino sugar residue], and retention of 3-hydroxydecanoate [3-OH C10 fatty acid]) were determined for Pseudomonas aeruginosa isolates from patients with cystic fibrosis (CF; n=86), from the environment (n=13), and from patients with other conditions (n=14). Among P. aeruginosa CF isolates, 100% had lipid A with palmitate, 24.6% with aminoarabinose, and 33.3% retained 3-hydroxydecanoate. None of the isolates from the environment or from patients with other conditions displayed these modifications. These results indicate that unique lipid A modifications occur in clinical P. aeruginosa CF isolates.

Topics: Arabinose; Child; Child, Preschool; Chronic Disease; Cystic Fibrosis; Decanoic Acids; Humans; Infant; Lipid A; Lung Diseases; Palmitates; Prevalence; Pseudomonas aeruginosa; Pseudomonas Infections

Cystic fibrosis (CF) patients develop chronic airway infections with Pseudomonas aeruginosa (PA). Pseudomonas aeruginosa synthesized lipopolysaccharide (LPS) with a variety of penta- and hexa-acylated lipid A structures under different environmental conditions. CF patient PA synthesized LPS with specific lipid A structures indicating unique recognition of the CF airway environment. CF-specific lipid A forms containing palmitate and aminoarabinose were associated with resistance to cationic antimicrobial peptides and increased inflammatory responses, indicating that they are likely to be involved in airway disease.

Topics: Acylation; Antimicrobial Cationic Peptides; Arabinose; Bacterial Proteins; Cells, Cultured; Cystic Fibrosis; Drug Resistance, Microbial; Humans; Infant; Interleukin-8; Lipid A; Lipopolysaccharides; Magnesium; Mutation; Palmitates; Peptides; Polymyxins; Pseudomonas aeruginosa; Pseudomonas Infections; Respiratory System; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Virulence

A hybridoma cell line producing a human anti-lipid A monoclonal antibody (mAb), FKF-IF3 (IgM (k)) was obtained by cell fusion of Epstein-Barr virus-transformed cells and mouse myeloma. The mAb bound to not only Gram-negative bacterial lipid A, but also to polysaccharide portions of Pseudomonas aeruginosa lipopolysaccharides (LPS). The mAb seemed to recognize two distinct regions of P. aeruginosa LPS other than lipid A, namely the outer core regions of some serotype strains and the O-polysaccharide region of serotype A strains. The mAb cross-reacted with N-acetyl-beta-glucosamine-conjugated bovine serum albumin, N-acetyl-beta-galactosamine-conjugated bovine serum albumin, myosin and actin, but not with other autoantigens such as ss- and ds-DNA, cardiolipin and glycosaminoglycans. The mAb conferred protective activity against a mouse pseudomonal infection model. The evidence suggested that the mAb was a naturally occurring polyspecific antibody that participated in defense against pseudomonal infections.

Topics: Acetylgalactosamine; Acetylglucosamine; Actins; Animals; Antibodies, Monoclonal; Autoantibodies; Blotting, Western; Cross Reactions; DNA; DNA, Single-Stranded; Electrophoresis, Polyacrylamide Gel; Humans; Immunization, Passive; Lipid A; Lipopolysaccharides; Mice; Myosins; O Antigens; Pseudomonas aeruginosa; Pseudomonas Infections; Serum Albumin, Bovine; Tumor Cells, Cultured

The low endotoxic lipid A derived from Porphyromonas gingivalis 381, 1-phospho beta(1-6)-linked glucosamine disaccharide with 3-hydroxy-15-methylhexadecanoyl and 3-hexadecanoyloxy-15-methylhexadecanoyl groups at the 2- and 2'-positions, respectively, induced mitogenic responses in LPS low responder C3H/HeJ as well as LPS responder C3H/HeN mouse splenocytes. The mitogenic activities of P. gingivalis lipid A in splenocytes of LPS responder mice were comparable to that of the synthetic Escherichia coli-type lipid A (compound 506). The addition of polymyxin B resulted in the inhibition of mitogenic activity. P. gingivalis lipid A also stimulated strongly nonspecific host resistance against Pseudomonas aeruginosa infection in BALB/c mice, and specific immune response in guinea pigs against infection with P. gingivalis. Furthermore, P. gingivalis lipid A demonstrated antitumour activity against MH134 hepatoma in C3H/HeN mice. These life-preserving with tumour regression properties were comparable to those of monophosphoryl lipid A derived from Salmonella minnesota Re 595. Thus, P. gingivalis lipid A appears to have beneficial properties as an immunopharmacological agent.

Topics: Adjuvants, Immunologic; Animals; Bacteroidaceae Infections; Guinea Pigs; Immunity, Innate; Lipid A; Liver Neoplasms, Experimental; Lymphocyte Activation; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Mice, Nude; Porphyromonas gingivalis; Pseudomonas Infections; Spleen

Antibodies were raised in rabbits by immunization with the heat-killed J5 mutant of Escherichia coli O111 (Rc chemotype). Serum antibodies were separated into purified IgG and IgM by sequential affinity chromatography on protein G-Sepharose and anti-rabbit IgG-Sepharose columns. J5 lipopolysaccharide (LPS)-specific IgG was prepared by affinity chromatography of purified IgG on a J5 LPS-EAH Sepharose 4B affinity column. Purified IgM, IgG, and J5 LPS-specific IgG protected neutropenic rats against lethal challenge with Pseudomonas aeruginosa 12:4:4 (Fisher Devlin immunotype 6). Nine of 16 rats treated with the IgM fraction were protected (P < .001). Thirteen of 20 rats treated with the purified IgG and 6 of 8 treated with J5 LPS-specific IgG were protected compared with none of 25 treated with IgG made from the preimmune serum of the same rabbit (P < .001). These results demonstrate that purified J5 LPS-specific IgG protects against the lethal consequences of gram-negative bacteremia.

Topics: Animals; Antibody Specificity; Bacteremia; Bacterial Vaccines; Blotting, Western; Chromatography, Affinity; Enzyme-Linked Immunosorbent Assay; Escherichia coli; Female; Immunodiffusion; Immunoglobulin G; Lipid A; Lipopolysaccharides; Neutropenia; Pseudomonas aeruginosa; Pseudomonas Infections; Rabbits; Rats; Rats, Sprague-Dawley

Despite the use of modern broad spectrum antibiotics nosocomial infections are an unsolved problem, especially in the field of neonatal intensive care (preterm babies and newborns). In patients with septic shock human monoclonal antibodies in combination with appropriate antibiotics have proven effective and compatible for children older than one year. So far, there have been no reports in the literature on the application of such kind of antiendotoxin immunotherapy for pre-term babies and newborns. We describe the effectiveness of monoclonal antibodies in two newborns. Already 12 respectively 16 hours after application of the human monoclonal IgM antibodies (Centoxin) and appropriate antibiotics, the clinical condition of our patients stabilized. Consecutively further clinical symptoms improved rapidly.

Topics: Anti-Bacterial Agents; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antibody Specificity; Combined Modality Therapy; Cross Infection; Female; Hirschsprung Disease; Humans; Infant, Newborn; Infant, Premature, Diseases; Lipid A; Microbial Sensitivity Tests; Pseudomonas aeruginosa; Pseudomonas Infections; Shock, Septic; Surgical Wound Infection

Topics: Animals; Cyclophosphamide; Exudates and Transudates; Female; Immunosuppression Therapy; Lipid A; Mice; Mice, Inbred ICR; Pseudomonas aeruginosa; Pseudomonas Infections

The C1 position of lipid A-subunit analogue GLA-27, 4-O-phosphono-D-glucosamine carrying N-3-tetradecanoyloxytetradecanoyl(C14-O-(C14)) and 3-O-tetradecanoyl (C14) groups, was S-acetylated, thiolated or phosphorylated. Enhancement of nonspecific resistance to Pseudomonas aeruginosa and vaccinia virus infections of these chemically modified compounds were investigated. Thiolation augmented the nonspecific resistance to P. aeruginosa infection. Protective activity against vaccinia virus infection was reduced by all the chemical modifications. NK cell activity was found not to be effected by S-acetylation, but to be decreased slightly by thiolation or phosphorylation. IFN-inducing activity was reduced remarkably by thiolation or S-acetylation, or completely diminished by phosphorylation, compared with that of GLA-27.

Topics: Animals; Female; Immunity, Innate; Interferons; Killer Cells, Natural; Lipid A; Mice; Mice, Inbred ICR; Pseudomonas Infections; Structure-Activity Relationship; Vaccinia

Non-specific protective activities against vaccinia virus (VV) and Pseudomonas aeruginosa infections as well as interferon (IFN)-inducing, natural killer (NK) cell and macrophage activation activities of chemically synthesized lipid A-subunit analogs were investigated. The analogs are 4-O-phosphono-D-glucosamine derivatives carrying different 2-N- and 3-O-linked acyl substituents such as (R)-3-tetradecanoyloxytetradecanoyl (C14-O-(C14)), (R)-3-hydroxytetradecanoyl (C14-OH) and tetradecanoyl (C14) groups. Compounds GLA-59 and GLA-60, which possess C14-OH and C14-O-(C14) groups as their acyl substituents, showed stronger IFN-inducing and anti-vaccinia virus activities than GLA-27 and GLA-68, which possess a C14 group instead of the C14-OH group in GLA-59 and GLA-60, although NK cell activation activity was similarly high in all of these compounds. In protective activity against P. aeruginosa infection and macrophage activation activity, GLA-60 and GLA-68, which carry a C14-O-(C14) group at the 3-O-position, expressed higher activities than GLA-27 and GLA-59, which carry the acyloxyacyl group at the 2-N-position. These results indicate that the acyl substituent (whether the counterpart of the C14-O-(C14) group is a C14 or a C14-OH group) and the binding position of the acyloxyacyl group at the 2-N- or the 3-O-position strongly influence the manifestation of antimicrobial and immunomodulating activities in different ways depending on the activity. Among the compounds, GLA-60 satisfied the structure requirements for protection against both VV and P. aeruginosa infections. This compound is a hopeful immunomodulator for prevention against broad microbial infections.

Topics: Adjuvants, Immunologic; Animals; Drug Resistance; Glucosamine; Lipid A; Mice; Mice, Inbred ICR; Pseudomonas Infections; Structure-Activity Relationship; Vaccinia

Enhancement of nonspecific resistance against Pseudomonas aeruginosa infection and regression of growth of Meth A fibrosarcoma by chemically synthesized lipid A-subunit analogs, 4-O-phosphono-D-glucosamine derivatives carrying 3-O- and N-linked acyl groups, were investigated. Compounds carrying an (R)-3-hydroxytetradecanoyl (C14-OH) group at the 2-N-position with (R)-3-tetradecanoyloxytetradecanoyl [C14-O-(C14)] or (R)-3-dodecanoyloxytetradecanoyl [C14-O-(C12)] groups at the 3-O-position, termed GLA-60 or GLA-63, respectively, showed strong activity about one-tenth that of natural lipid A. The protective activity of compounds carrying an (R)-3-hexadecanoyloxytetradecanyl group instead of a C14-O-(C14) or C14-O-(C12) group was very weak. GLA-59 carrying the same acyl components as those of GLA-60 but with reversed binding sites showed significant but not so strong protective activity. The activity of compounds possessing a tetradecanoyl group instead of a C14-OH group in GLA-60 or GLA-63 was weaker than that of GLA-60 or GLA-63. Intravenous or intratumoral administration of GLA-59, GLA-60 and GLA-63 induced significant regression of Meth A fibrosarcoma in terms of tumor size, tumor weight and number of cured mice. The activity of GLA-59 was almost equivalent to that of GLA-60. None of the tested compounds exhibited significant pyrogenicity at a dose of 10 micrograms/kg in rabbits.

Topics: Adjuvants, Immunologic; Animals; Bacterial Infections; Female; Fibrosarcoma; Glucosamine; Immunity, Innate; Lipid A; Mice; Mice, Inbred BALB C; Mice, Inbred ICR; Neoplasm Transplantation; Pseudomonas Infections

Activities for enhancing nonspecific host resistance against microbial infections and growth inhibition against tumors by a lipid A-subunit analogue GLA-27 were investigated. GLA-27, a 4-O-phosphono-D-glucosamine derivative with 2-N-3-tetradecanoyloxytetradecanoyl and 3-O-tetradecanoyl group, inhibited significantly the growth of solid-type tumors RL male 1 lymphoma and Meth A fibrosarcoma. In the case of RL male 1 lymphoma, 2.5 micrograms of GLA-27 was needed to exhibit the activity, while for Meth A fibrosarcoma, 250 micrograms of GLA-27 was needed. On the other hand, tail lesions induced by intravenous inoculation with vaccinia virus were effectively suppressed in mice injected with 1 microgram of GLA-27 1 day before the viral injection. The antiviral activity of GLA-27 was 100 times higher than that of MDP by ED50. GLA-27 also showed nonspecific protective activity against Pseudomonas aeruginosa infection at a dose of 30 micrograms/mouse, although the activity was far less than that induced by lipid A. GLA-27 did not exhibit toxic activities such as pyrogenicity and Shwartzman reaction.

Topics: Adjuvants, Immunologic; Animals; Anti-Bacterial Agents; Antineoplastic Agents; Antiviral Agents; Drug Evaluation, Preclinical; Lipid A; Male; Mice; Mice, Inbred Strains; Neoplasms, Experimental; Pseudomonas Infections; Vaccinia

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