The fatty acid content of the Bordetella pertussis endotoxin

The fatty acid content of Bordetella pertussis endotoxin has been estimated by several methods. Expressed as 3-hydroxytetradecanoic acid, it was 0.74 mumol (mg lyophilized material)-1, 0.38 mumol being ester-bound, and 0.32 mumol in amide linkage. Reported molar ratios of ester-bound to amide-bound fatty acids in endotoxins of various bacterial species range from 2.4 to 2 in B. pertussis, to 5 to 2 in Salmonella minnesota; according to these figures large differences must exist in the degree of substitution, and the substitution pattern of the glucosaminyl-beta-1,6-glucosamine unit present in the hydrophobic region of endotoxins. When fatty acids, released by acid and alkaline hydrolyses of the B. pertussis endotoxin, were extracted into chloroform, unidentified chromogenic substances appearing in the extract interfered with their colorimetric estimation; no interference was observed when hexane was used instead of chloroform.     

Endotoxin-induced hypersensitivity to histamine in mice. I. Contrasting effects of bacterial lipopolysaccharides and the classical histamine-sensitizing factor of Bordetella pertussis

Pieroni, Robert E. (Massachusetts Department of Public Health, Boston), Edward J. Broderick, and Leo Levine. Endotoxin-induced hypersensitivity to histamine in mice. I. Contrasting effects of bacterial lipopolysaccharides and the classical histamine-sensitizing factor of Bordetella pertussis. J. Bacteriol. 91:2169-2174. 1966.-The capacity of typhoid and possibly of pertussis endotoxins to induce histamine-shock susceptibility in some of the mice that survive graded doses of these endotoxins was confirmed. It was demonstrated, however, that pertussis endotoxin cannot be the main source of the typical histamine sensitization of pertussis vaccine. The following points are made. (i) With typhoid and pertussis endotoxins as inducers of histamine shock, no systematic relation between deaths and induction dose could be found, and 100% mortality could not be achieved. In contrast, with pertussis protective fraction as inducer, there was clear dose-response regression, with 100% mortality possible. (ii) The major part of the histamine-sensitizing activity of pertussis vaccine or its extracts was destroyed by trypsinization or by heating for 30 min at 100 C. These processes do not affect the histamine-sensitizing activity of the endotoxins. The implication for purified pertussis vaccine with high histamine-sensitization capacity is that endotoxin need not necessarily be present. The significance and possible mechanisms of action of endotoxin-induced histamine sensitivity are briefly discussed.     

The influence of Bordetella pertussis and its constituents on the beta-adrenergic receptor in the guinea pig respiratory system

In the present study, the effect of vaccination of guinea pigs with Bordetella pertussis was investigated, 4 days after treatment, on the cholinergic and beta-adrenergic receptor function in isolated tracheal spirals and the number of beta-adrenoceptor binding sites in guinea pig lung. It was found that B. pertussis caused an impairment in the beta-adrenoceptor function and a decrease in its number. Similar results were obtained with endotoxin. Leucocytosis promoting factor, however, was ineffective. These results indicate that endotoxin is the constituent responsible for the beta-adrenoceptor blocking effects of the bacterium. Also the combined whole cell diphtheria, B. pertussis and tetanus toxoid vaccine induced a beta-adrenoceptor blockade; the acellular vaccine was less effective. The results obtained with the B. pertussis vaccines are discussed in relation to the possible side-effects that sometimes occur after immunization of infants.     

Signalling and cellular specificity of airway nitric oxide production in pertussis

Bordetella pertussis , the aetiological agent of whooping cough (pertussis), causes selective destruction of ciliated cells of the human airway mucosa. In a hamster tracheal organ culture model, B. pertussis causes identical cytopathology as does tracheal cytotoxin (TCT), a glycopeptide released by the bacterium. The damage caused by B. pertussis or TCT has been shown to be mediated via nitric oxide (NO·). Using immunofluorescence detection of the cytokine-inducible NO synthase (iNOS; NOS type II), we determined that B. pertussis induced epithelial NO· production exclusively within non-ciliated cells. This epithelial iNOS activation could be reproduced by the combination of TCT and endotoxin. However, neither TCT alone nor endotoxin alone was capable of inducing epithelial iNOS. This result mirrors the synergistic activity of TCT and endotoxin exhibited in monolayer cultures of tracheal epithelial cells. Therefore, TCT and endotoxin are both important virulence factors of B. pertussis , combining synergistically to cause the specific epithelial pathology of pertussis.     

Variations in the carbohydrate regions of Bordetella pertussis lipopolysaccharides: electrophoretic, serological, and structural features.

Structural and immunological differences between the two components that are usually present in unequal quantities in Bordetella pertussis endotoxin preparations and are visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis have been studied by using strains 1414, A100, and 134, all in phase I. According to analyses by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and thin-layer chromatography, the minor (8%) component of the endotoxin of strain 1414 (endotoxin 1414) appeared to be the predominating component of endotoxins A100 and 134. The masses of the carbohydrate chains isolated from endotoxin A100 and from the major component of endotoxin 1414 were 1,649 and 2,311 atomic mass units, respectively, as determined by 252Cf plasma desorption mass spectrometry. Comparison of the 1H nuclear magnetic resonance spectra of these chains established that four N-acetyl groups, an N-methyl group, and a 6-deoxy function, which characterize the nonreducing, distal trisaccharide of the glycose chain of strain 1414, were absent from that of strain A100. The antigenicity of endotoxin 1414, as measured by enzyme-linked immunosorbent assay, was higher than that of endotoxin A100, but fell below it when the glycose chain of endotoxin 1414 was deprived of seven sugars by treatment with nitrous acid. This observation suggests that at least three (distal, proximal, and intermediate) regions of the glycose chain of endotoxin 1414 carry antigenic determinants. One of these, located in the distal trisaccharide, is absent from both endotoxins A100 and 134.     

Human MD-2 discrimination of meningococcal lipid A structures and activation of TLR4

MD-2, a eukaryotic accessory protein, is an essential component for the molecular pattern recognition of bacterial endotoxins. MD-2 interacts with lipid A of endotoxins [lipopolysaccharide (LPS) or lipooligosaccharide (LOS)] to activate human toll-like receptor (TLR) 4. The structure of lipid A influences the subsequent activation of human TLR4 and the immune response, but the basis for the discrimination of lipid A structures is unclear. A recombinant human MD-2 (rMD-2) protein was produced in the Pichia pastoris yeast expression system. Human embryonic kidney (HEK293) cells were transfected with human TLR4 and were stimulated with highly purified LOS (0.56 pmol) from Neisseria meningitidis or LPS from other structurally defined bacterial endotoxins in the presence or absence of human rMD-2. Human rMD-2 restored, in a dose-dependent manner, interleukin (IL-8) responsiveness to LOS or LPS in TLR4-transfected HEK293 cells. The interaction of endotoxin with human rMD-2 was then assessed by enzyme-linked immunosorbent assays. Wild-type meningococcal LOS (Wt m LOS) bound human rMD-2, and binding was inhibited by an anti-MD-2 antibody to MD-2 dose-dependently (P < 0.005). Wt m LOS or meningococcal KDO(2)-lipid A had the highest binding affinity for human rMD-2; unglycosylated meningococcal lipid A produced by meningococci with defects in the 3-deoxy-d-manno-2-octulosonic acid (KDO) biosynthesis pathway did not appear to bind human rMD-2 (P < 0.005). The affinity of meningococcal LOS with a penta-acylated lipid A for human rMD-2 was significantly less than that for hexa-acylated LOS (P < 0.05). The hierarchy in the binding affinity of different lipid A structures for human rMD-2 was directly correlated with differences in TLR4 pathway activation and cytokine production by human macrophages.     

Species-Specific Activation of TLR4 by Hypoacylated Endotoxins Governed by Residues 82 and 122 of MD-2

The Toll-like receptor 4/MD-2 receptor complex recognizes endotoxin, a Gram-negative bacterial cell envelope component. Recognition of the most potent hexaacylated form of endotoxin is mediated by the sixth acyl chain that protrudes from the MD-2 hydrophobic pocket and bridges TLR4/MD-2 to the neighboring TLR4 ectodomain, driving receptor dimerization via hydrophobic interactions. In hypoacylated endotoxins all acyl chains could be accommodated within the binding pocket of the human hMD-2. Nevertheless, tetra- and pentaacylated endotoxins activate the TLR4/MD-2 receptor of several species. We observed that amino acid residues 82 and 122, located at the entrance to the endotoxin binding site of MD-2, have major influence on the species-specific endotoxin recognition. We show that substitution of hMD-2 residue V82 with an amino acid residue with a bulkier hydrophobic side chain enables activation of TLR4/MD-2 by pentaacylated and tetraacylated endotoxins. Interaction of the lipid A phosphate group with the amino acid residue 122 of MD-2 facilitates the appropriate positioning of the hypoacylated endotoxin. Moreover, mouse TLR4 contributes to the agonistic effect of pentaacylated msbB endotoxin. We propose a molecular model that explains how the molecular differences between the murine or equine MD-2, which both have sufficiently large hydrophobic pockets to accommodate all five or four acyl chains, influence the positioning of endotoxin so that one of the acyl chains remains outside the pocket and enables hydrophobic interactions with TLR4, leading to receptor activation.     

Endotoxin depletion of recombinant protein preparations through their preferential binding to histidine tags

The presence of endotoxins in preparations of recombinantly produced therapeutic proteins poses serious problems for patients. Endotoxins can cause fever, respiratory distress syndromes, intravascular coagulation, or endotoxic shock. A number of methods have been devised to remove endotoxins from protein preparations using separation procedures based on molecular mass or charge properties. Most of the methods are limited in their endotoxin removal capacities and lack general applicability. We are describing a biotechnological approach for endotoxin removal. This strategy exploits the observation that endotoxins form micelles that expose negative charges on their surface, leading to preferential binding of endotoxins to cationic surfaces, allowing the separation from their resident protein. Endotoxins exhibit high affinity to stretches of histidines, which are widely used tools to facilitate the purification of recombinant proteins. They bind to nickel ions and are the basis for protein purification from cellular extracts by immobilized metal affinity chromatography. We show that the thrombin-mediated cleavage of two histidine tags from the purified recombinant protein and the adsorption of these histidine tags and their associated endotoxins to a nickel affinity column result in an appreciable depletion of the endotoxins in the purified protein fraction.     

Protein concentration effect on protein-lipopolysaccharide (LPS) binding and endotoxin removal

It is known some proteins can disaggregate endotoxins and form complexes with lipopolysaccharide (LPS). Nevertheless, how protein concentration affects protein-LPS binding and endotoxin removal is unknown. In this study, protein samples at various concentrations were incubated with endotoxin samples at a fixed concentration. The mixtures were filtered by ultrafiltration membranes. As protein concentration increased, the amount of endotoxin detected in the filtrates increased too. This result indicates protein concentration has significant effect on protein-LPS binding and the amount of endotoxin disaggregated.     

Lipopolysaccharide receptor on rabbit peritoneal macrophages. I. Binding characteristics

The Bordetella pertussis endotoxin, labeled with tritium ((3H)-LPS), bound irreversibly and nonspecifically to rabbit lung macrophages, but bound reversibly and specifically to both resident and elicited rabbit peritoneal macrophages. The specific binding capacity of the macrophages was saturated with about 3 X 10(4) LPS molecules per cell. The binding was inhibited with the homologous unlabeled endotoxin, but not at all with endotoxin from Proteus mirabilis, thus assessing ligand specificity. Endotoxins from other bacteria gave intermediate inhibition value. Binding of tritium-labeled pertussis endotoxin was significantly inhibited by one of the two polysaccharides (PS-1) present in this endotoxin, but neither the other polysaccharide (PS-2) nor the Lipid A fragment exhibited such activity. These results strongly suggest the presence of a lectin-like receptor for LPS on the membrane of rabbit peritoneal macrophages.     

Comparison of the effects of several endotoxin preparations on body temperature and metabolic rate in the rat

The effects of several bacterial endotoxins on body temperature and resting oxygen consumption (VO2) were compared in normal rats. Low doses (0.05 mg/kg, i.m.) of 0127:B8 phenol-extracted endotoxin caused significant increases in both parameters. Maximal febrile responses (+1.6 degrees C) occurred at a dose of 0.05 mg/kg, but higher doses produced smaller effects. The maximal increase in VO2 (17%) occurred at doses of 0.5-1.0 mg/kg. A TCA extract of the same strain of endotoxin elicited a similar pattern of responses but was less potent than the phenol extract, whereas another endotoxin 026:B6 (TCA extract) was much less potent. The data illustrate the importance of constructing dose-response curves when comparing different endotoxins and indicate that in the rat, oxygen consumption provides a useful index of the response to pyrogens.     

A novel type of endotoxin structure present in Bordetella pertussis. Isolation of two different polysaccharides bound to lipid A.

The endotoxin of Bordetella pertussis was cleaved by mild acidic hydrolysis to yield a polysaccharide (polysaccharide I, 15%), a glycolipid (63%) and lipid X (2%). Further treatment of the glycolipid with stronger acid released a second polysaccharide (polysaccharide II, 9%) and material similar to lipid A present in enterobacterial endotoxins. Both polysaccharides possess a single molecule of 3-deoxy-2-octulosonic acid as the reducing, terminal sugar. In polysaccharide II the octulosonic acid is phosphorylated in position 5 and presumably substituted in position 4; in polysaccharide I the octulosonic acid is not phosphorylated, but is substituted in position 5. Following treatment of the endotoxin with strong base, a fragment was isolated that contained bound, non-phosphorylated 3-deoxy-2-octulosonic acid, glucosamine phosphate and fatty acids. This indicated that polysaccharide I, like polysaccharide II, was bound to the lipid region of the endotoxin. The endotoxin structure thus defined is different from that proposed for the lipopolysaccharides of enterobacteria.     

Biochemical and electron microscopy analysis of the endotoxin binding to microtubulesin vitro

The mechanisms involved in cellular activation and damage by bacterial endotoxins are not completely defined. In particular, there is little information about possible intracellular targets of endotoxins. Recently, the participation of a microtubule associated protein in endotoxin actions on macrophages has been suggested. In the present work, we have studied the effect ofE. coli lipopolysaccharide on the polymerization of microtubular proteinin vitro. Electrophoretic analysis of the polymerization mixtures showed that the endotoxin inhibited the polymerization when present at high concentrations. At lower concentrations, LPS selectively displaced the microtubule associated protein MAP-2 from the polymerized microtubules. Electron microscopy showed that LPS binds to microtubules of tubulin+MAPs and to microtubules of purified tubulin (without MAPs) polymerized with taxol. Gel filtration experiments confirmed the binding of LPS to tubulin, and by ligand blot assays an interaction LPS — MAP-2 was detected. The ability of LPS to interact with microtubular proteins suggests a possible participation of microtubules on the cellular effects of endotoxins.     

Biophysical characterization of the interaction of high-density lipoprotein (HDL) with endotoxins.

The interaction of bacterial endotoxins [lipopolysaccharide (LPS) and the 'endotoxic principle' lipid A], with high-density lipoprotein (HDL) from serum was investigated with a variety of physical techniques and biological assays. HDL exhibited an increase in the gel to liquid crystalline phase transition temperature Tc and a rigidification of the acyl chains of the endotoxins as measured by Fourier-transform infrared spectroscopy and differential scanning calorimetry. The functional groups of the endotoxins interacting with HDL are the phosphates and the diglucosamine backbone. The finding of phosphates as target groups is in accordance to measurements of the electrophoretic mobility showing that the zeta potential decreases from -50 to -60 mV to -20 mV at binding saturation. The importance of the sugar backbone as further target structure is in accordance with the remaining negative potential and competition experiments with polymyxin B (PMB) and phase transition data of the system PMB/dephosphorylated LPS. Furthermore, endotoxin binding to HDL influences the secondary structure of the latter manifesting in a change from a mixed alpha-helical/beta-sheet structure to a predominantly alpha-helical structure. The aggregate structure of the lipid A moiety of the endotoxins as determined by small-angle X-ray scattering shows a change of a unilamellar/inverted cubic into a multilamellar structure in the presence of HDL. Fluorescence resonance energy transfer data indicate an intercalation of pure HDL, and of [LPS]-[HDL] complexes into phospholipid liposomes. Furthermore, HDL may enhance the lipopolysaccharide-binding protein-induced intercalation of LPS into phospholipid liposomes. Parallel to these observations, the LPS-induced cytokine production of human mononuclear cells and the reactivity in the Limulus test are strongly reduced by the addition of HDL. These data allow to develop a model of the [endotoxin]/[HDL] interaction.     

Detergent-accelerated hydrolysis of bacterial endotoxins and determination of the anomeric configuration of the glycosyl phosphate present in the "isolated lipid A" fragment of the Bordetella pertussis endotoxin

Due to the formation of micelles, severance of the hydrophilic (poly- or oligosaccharide) and hydrophobic ("Lipid A") domains of bacterial lipopolysaccharides at pH 3.4 or 4.5 and 100 degrees is slow and sometimes does not proceed at all; partially degraded fragments are usually formed. At pH 3.4 (100 degrees) in aqueous 1% sodium dodecylsulphate (SDS), both lipopolysaccharides of the Bordetella pertussis endotoxin are cleaved within 20-30 min, but 80% of the glycosidically bound phosphate present in the hydrophobic domain is lost. Other endotoxins behave similarly. At pH 4.5 (100 degrees) and in the absence of detergent, hydrolysis of the glycosidic bonds of 3-deoxy-D-manno-2-octulosonic acid residues of the B. pertussis endotoxin is negligible but, in aqueous 1% SDS, severance of the two regions of LPS 1 is complete within 1 h (that of LPS-2 requires 3-4 h), and the glycosidically bound phosphate of the isolated hydrophobic region is preserved. Comparison of the rate of acid-catalysed hydrolysis of the glycosidically bound phosphate present in this "isolated Lipid A" preparation with that of 2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-alpha- and -beta-D-glucopyranose 1-phosphates established that the former 1-phosphate was the alpha anomer.     

Altered responses to modulators of guanine nucleotide binding protein activity in endotoxin tolerance

The effects of cholera toxin or pertussis toxin and nonhydrolyzable GTP analogs on Salmonella enteritidis endotoxin stimulation of iTxB2 and i6-keto-PGF1 alpha synthesis in control and endotoxin tolerant rat peritoneal macrophages were determined. Pretreatment with pertussis toxin alone had no effect on basal macrophage iTxB2 or i6-keto-PGF1 alpha production, but pertussis toxin (0.1, 1.0 and 10 ng/ml) significantly inhibited endotoxin-stimulated iTxB2 and i6-keto-PGF1 alpha synthesis. Pretreatment with cholera toxin, which did not affect basal iTxB2 or i6-keto-PGF1 alpha synthesis, significantly enhanced endotoxin-induced synthesis of iTxB2 and i6-keto-PGF1 alpha. The effects of pertussis and cholera toxin with or without endotoxin were significantly (P less than 0.05) less in macrophages from endotoxin tolerant rats compared to control macrophages. GTP[gamma-S] (100 microM) significantly increased iTxB2 synthesis and significantly augmented endotoxin-stimulated iTxB2 synthesis in control macrophages (P less than 0.05). However, in macrophages from endotoxin tolerant rats the effect of GTP[gamma-S] on iTxB2 synthesis was significantly less (P less than 0.05) compared to control macrophages. Collectively, these data suggest that: (1) guanine nucleotide binding regulatory proteins mediate endotoxin-stimulated arachidonic acid metabolism in rat peritoneal macrophages; and (2) endotoxin tolerance induces alterations in guanine nucleotide binding protein activity.     

Bordetella pertussis fimbriae are effective carrier proteins in Neisseria meningitidis serogroup C conjugate vaccines

Serogroup C meningococcal conjugate vaccines generally use diphtheria or tetanus toxoids as the protein carriers. The use of alternative carrier proteins may allow multivalent conjugate vaccines to be formulated into a single injection and circumvent potential problems of immune suppression in primed individuals. Bordetella pertussis fimbriae were assessed as carrier proteins for Neisseria meningitidis serogroup C polysaccharide. Fimbriae were conjugated to the polysaccharide using modifications of published methods and characterised by size exclusion chromatography; co-elution of protein and polysaccharide moieties confirmed conjugation. The conjugates elicited boostable IgG responses to fimbriae and serogroup C polysaccharide in mice, and IgG:IgM ratios indicated that the responses were thymus-dependent. High bactericidal antibody titres against a serogroup C strain of N. meningitidis were also observed. In a mouse infection model, the conjugate vaccine protected against lethal infection with N. meningitidis. Therefore, B. pertussis fimbriae are effective carrier proteins for meningococcal serogroup C polysaccharide and could produce a vaccine to protect against meningococcal disease and to augment protection against pertussis.     

Effect of lead acetate on the susceptibility of rats to bacterial endotoxins

Selye, H. (Université de Montréal, Montreal, Canada), B. Tuchweber, and L. Bertók. Effect of lead acetate on susceptibility of rats to bacterial endotoxins. J. Bacteriol. 91:884-890. 1966.-A single, normally well-tolerated, intravenous injection of lead acetate increases the sensitivity of the rat to the endotoxins of various gram-negative bacteria about 100,000 times above normal. Under the conditions of these experiments, the mortality and organ changes normally produced by the intravenous injection of 100 mug of Escherichia coli endotoxin were essentially the same as those obtained by use of 1 nanogram in lead-sensitized rats. The sensitizing effect of lead acetate for E. coli endotoxin is greatest when the two agents are given simultaneously. However, considerable sensitization is still detectable when endotoxin is injected up to 1 hr before or 7 hr after sensitization with lead. No sensitization was noted when the endotoxin was administered 24 hr before or after lead acetate. Under our experimental conditions, the minimal dose of lead acetate which could still induce significant sensitization to E. coli endotoxin was 1 mg per 100 g of body weight. Although lead acetate induces a high degree of susceptibility to various endotoxins, other reticuloendothelial blocking agents did not acquire unusual toxicity after pretreatment with lead. Finally, none of the other metals or reticuloendothelial blocking agents tested could duplicate the pronounced decrease in endotoxin resistance induced by lead acetate.     

Behavioral responses of lightbrown apple moth neonate larvae on diets containing Bacillus thuringiensis formulations or endotoxins

Behavioral responses of individual lightbrown apple moth, Epiphyas postvittana (Walker), neonate larvae to Dipel or the Bacillus thuringiensis delta endotoxins CryIAc and CryIBa incorporated into artificial diets were measured in choice and no-choice treatments. Frass production and the spinning of silken shelters were delayed when larvae were given diets containing Dipel or Bt endotoxins. In choice treatments larvae did not exhibit an initial preference for control diets over diets with Dipel or Bt endotoxins but accumulated on control diets over a period of days, apparently because larvae that first settled on Dipel or endotoxin diets abandoned diets while larvae that fed on control diets remained on diets throughout the experiment. Abandonment of diets containing Dipel or endotoxins was also apparent in no-choice treatments. Larvae exposed to such diets were more likely to be observed walking or at different sites from one observation to the next, and produced frass and silken feeding shelters at multiple sites rather than a single site. The implications of these findings for the use of B. thuringiensis as a commercial spray or for the use of B. thuringiensis endotoxin genes as resistance factors to be expressed in transgenic apples are discussed.     

Binding of bacterial endotoxin (LPS) to encephalitogenic myelin basic protein and modulation of characteristic biologic activities of LPS

Myelin basic protein, isolated from central nervous system tissue and an inducer of experimental allergic encephalomyelitis in animals, has been demonstrated to form a stable molecular complex with the lipid A region of gram-negative bacterial lipopolysaccharides (endotoxins). This binding of endotoxin with myelin basic protein results in generation of lower m.w. aggregates with decreased isopycnic density. A number of lipid A-induced characteristic properties of endotoxin, such as B lymphocyte proliferative response in C3H/St mice, complement activation of normal human serum, Limulus lysate gelation, and lethal effects in mice, are modified as a result of binding of myelin basic protein with lipopolysaccharides.