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Biomedical subjects

E Ribi

Publications and source records attributed to E Ribi.

At least 19 recordsLinked to original sources
PubMed1988

Glycolipid induced proliferation of lipopolysaccharide hyporesponsive C3H/HeJ splenocytes.

Although the C3H/HeJ mouse is hyporesponsive to lipopolysaccharides (LPS), certain forms of the lipid A fraction have been shown to stimulate cells from this mouse strain. To determine the role of the oligosaccharide chain length on the lipid A-induced proliferation of C3H/HeJ splenocytes, a panel of glycolipids from R-chemotypes (Re, Rc, and Rd) and a nontoxic monophosphoryl lipid A (MPL) were tested. The MPL cells isolated from the MPL of Salmonella minnesota, Salmonella typhimurium, and the Reglycolipids isolated from Escherichia coli were found to be effective at stimulating the LPS-hyporesponsive spleen cells. A Re-glycolipid isolated from a different strain of E. coli cells was inactive, as were the S. minnesota Rc and Rd chemotypes. Proliferation induced by MPL and the active Re preparations was dose dependent and was inhibited by polymyxin B. Thus, if contamination of the Re-LPS or MPL with lipid A-associated protein occurred, it was below functional levels. The data suggest that the C3H/HeJ spleen cells are capable of responding to certain glycolipids, but they may lack the ability to convert native LPS into a stimulatory signal. In addition, a monosaccharide precursor of lipid A (lipid X), and a monoacyl glucosamine phospholipid derivative of lipid X (MaGP), were capable of inhibiting the proliferation induced by the MPL and Re-glycolipids. These data are compatible with the existence of a spleen cell receptor for lipid A.

Animals↗
PubMed1988

Effects of nontoxic lipid A and endotoxin on resistance of mice to Toxoplasma gondii.

Mice were administered nontoxic monophosphoryl lipid A (MPL) or refined standard bacterial endotoxin (RSE) prior to, simultaneously with, or after infection with Toxoplasma gondii. MPL and RSE given before or with the toxoplasma infection induced significant resistance. Administration of toxic RSE, but not nontoxic MPL, after the establishment of toxoplasma infection significantly shortened the survival time of mice.

Animals↗
PubMed1987

The adjuvant properties of a nontoxic monophosphoryl lipid A in hyporesponsive and aging mice.

The immunomodulatory action of a nontoxic monophosphoryl lipid A (MPL) and a toxic diphosphoryl lipid A (DPL) fraction derived from endotoxins of the heptoseless mutants of bacteria were studied. Both derivatives retained the ability characteristic of lipopolysaccharides, i.e., to enhance antibody formation in young adult mice when injected along with antigen and suppress antibody production when given 1 day before antigen. In aging mice, a model of immunodeficiency, a marked restoration of antibody formation was observed when antigen was injected together with either MPL or DPL. Levels of antibody in the aging mice became comparable with those observed in young adult mice. Moreover, both MPL and DPL enhanced antibody production significantly in the endotoxin low-responder mouse strains C3H/HeJ and C57Bl/10 ScN, whereas phenol-water-extracted endotoxin from an Rd mutant was ineffective. MPL and DPL also acted as suppressive agents when administered prior to antigen in the C3H/HeJ strain. Thus, the results from these studies show that the toxic properties of lipid A can be removed without eliminating immunomodulating activity and certain forms of lipid A can overcome the immunologic lesions of immunodeficient and hyporesponsive animals.

Adjuvants, Immunologic↗
PubMed1986

Immunobiological activities of nontoxic lipid A: enhancement of nonspecific resistance in combination with trehalose dimycolate against viral infection and adjuvant effects.

The ability of nontoxic monophosphoryl lipid A (MPL) to stimulate nonspecific resistance against viral infection was investigated. Mice pretreated intravenously with squalane-in-water emulsions of MPL, alone or in combination with other immunostimulants, were given an aerosol of influenza virus three weeks after the pretreatment. Complete protection against lethal influenza virus infection was conferred when MPL was combined with trehalose dimycolate (TDM). The protective activity of MPL plus TDM combination was corroborated by a significant reduction of the lung virus titers. Combination of lower doses of MPL with TDM extracted from Mycobacterium bovis, but not with that of M. phlei, induced significant resistance to influenza virus. Preparations containing MPL alone, or combined with mycobacterial cell wall skeleton or muramyl dipeptide, were not effective. The adjuvant activity of MPL on bivalent influenza subunit vaccine was also studied. The primary antibody responses to influenza A and influenza B antigens were enhanced by the addition of MPL and were higher than the vaccine associated with aluminum hydroxide. The adjuvant activity of MPL was confirmed by the elevated secondary response. High levels of circulating antibodies were still present in the MPL group when antibody titers in the controls were waning.

Adjuvants, Immunologic↗
PubMed1986

Effect of monophosphoryl lipid A on host resistance to bacterial infection.

The ability of monophosphoryl lipid A (MPLA) to enhance nonspecific host resistance to bacterial infections was studied. Mice were treated with MPLA prior to intraperitoneal challenge with Escherichia coli or Staphylococcus epidermidis. Animals received additional MPLA for 2 days postinfection, and survival rates were determined. Ten micrograms of MPLA per mouse significantly improved the survival of animals infected with either bacterial species. Dose-response studies showed significant MPLA-induced protection at doses of 6 micrograms/kg against E. coli challenge and 60 micrograms/kg against S. epidermidis challenge.

Adjuvants, Immunologic↗
PubMed1986

Enhancement of chemiluminescence and phagocytic activities by nontoxic and toxic forms of lipid A.

The effect on the respiratory burst of murine splenic cells after in vitro exposure to nontoxic monophosphoryl lipid A (MPL), toxic diphosphoryl lipid A (DPL), and refined standard endotoxin (RSE) was studied by luminol-dependent, zymosan-stimulated chemiluminescence (CL). CL was stimulated only to a minimum degree by 0.1 micrograms of MPL, DPL, or RSE, but this was clearly increased when 10-fold higher doses were used. CL activity generated by RSE, which contains only lipid A and ketodeoxyoctanate, remained at a moderate level, even when 100-fold higher doses were used. In contrast, ketodeoxyoctanate-free DPL elevated CL in a dose-dependent manner. Nontoxic MPL at a high dose significantly enhanced CL generation to levels that were comparable to those stimulated by DPL. In addition, phagocytosis of freshly prepared fluorescent beads by adherent peritoneal macrophages was enhanced seven- to 10-fold by toxic DPL and reference LPS, and fivefold by nontoxic MPL.

Animals↗
PubMed1985

Monophosphoryl lipid A obtained from lipopolysaccharides of Salmonella minnesota R595. Purification of the dimethyl derivative by high performance liquid chromatography and complete structural determination.

The monophosphoryl lipid A (MLA) obtained from the lipopolysaccharides of Salmonella minnesota R595 was fractionated on a silicic acid column to yield the heptaacyl, hexaacyl, and pentaacyl MLA. Each of these MLAs was methylated with diazomethane to yield the dimethyl derivative and purified to homogeneity by reverse-phase high performance liquid chromatography. The molecular ions obtained by positive ion fast atom bombardment mass spectrometry of purified dimethyl heptaacyl MLA allowed us to establish the molecular formula and Mr of C112H211N2O23P and 1983.3, respectively. Cleavage at the glycosidic linkage yielded an oxonium ion of mass 1115, which showed that the distal sugar unit contained one phosphate (dimethyl), two hydroxymyristates, one laurate, and one myristate, while the reducing sugar unit contained two hydroxymyristates and one palmitate. By utilizing two-dimensional NMR spectroscopy, we were able to assign all of the protons of dimethyl heptaacyl MLA. This assignment included the beta protons of the three acyloxyacyl groups. A substantial downfield shift of the protons at the 3- and 3' -carbons was observed, which indicated that these two positions are occupied by ester groups. Fast atom bombardment mass spectral analysis of the hexaacyl and pentaacyl MLAs showed that these structures were identical to the previously designated TLC-3 and TLC-5 fractions, respectively, from Salmonella typhimurium. From this study, the complete structures of the MLA series found in the LPS of S. minnesota can now be described.

Chemical Phenomena↗
PubMed1985

Trehalose dimycolate from various mycobacterial species induces differing anti-infectious activities in combination with muramyl dipeptide.

Significant resistance against influenza virus and Mycobacterium tuberculosis infections was induced when trehalose dimycolate from M. tuberculosis or M. bovis but not M. avium was combined with muramyl dipeptide. Trehalose dimycolate from M. tuberculosis, in contrast to that from M. avium, could confer resistance against Toxoplasma gondii infections.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1985

Bacterial endotoxin selectively prevents the expression of scavenger-receptor activity on human monocyte-macrophages.

Concentrations of bacterial lipopolysaccharide (LPS) as low as 1 ng/ml suppressed the activity of the scavenger receptor on cultured human monocyte-macrophages. In contrast, concentrations of LPS as high as 100 ng/ml had no effect on the activity of the low density lipoprotein (LDL) receptor. LPS and purified forms of the lipid A moiety of LPS were effective in suppressing scavenger receptor activity. However, acid hydrolysis of the labile phosphate group of the native diphosphorylated lipid A to form monophosphoryl lipid A rendered the molecule ineffective in suppressing scavenger receptor activity. LPS at a concentration of 100 ng/ml had no effect on the secretion of apolipoprotein E, phagocytic activity, tumoricidal activity, or the protein content of monocyte-macrophages. We conclude that the active component of LPS that mediates suppression of scavenger receptor activity is diphosphoryl lipid A.

Apolipoproteins E↗
PubMed1984

Influence of fine structure of lipid A on Limulus amebocyte lysate clotting and toxic activities.

We examined the relationship between the fine structure of lipid A and the toxicity of endotoxin or lipopolysaccharides as measured by the Limulus amebocyte lysate (LAL), rabbit pyrogenicity, chicken embryo lethal dose, and dermal Shwartzman reaction tests. Lipid A and lipid A-like compounds obtained from deep-rough mutants of Salmonella spp. and Escherichia coli had a wide range of structural variations. These compounds included native lipopolysaccharides, diphosphoryl and monophosphoryl lipid A's, and lipid X (a monosaccharide). The LAL test was positive for all lipids tested with lysates from Travenol Laboratories and from Associates of Cape Cod (2.9 X 10(3) to 2.6 X 10(7) endotoxin units per mg), except for O-deacylated and dephosphorylated lipid X, which were negative. The Mallinckrodt lysate gave negative tests for lipid X. In the rabbit pyrogenicity and chicken embryo lethal dose tests, only native lipopolysaccharide and diphosphoryl lipid A's were judged toxic. The Shwartzman reaction was positive for a specific purified diphosphoryl lipid A (thin-layer chromatography-3 fraction) but negative for the purified monophosphoryl lipid A (also a thin-layer chromatography-3 fraction). These results show that the LAL test is not a valid measure of all parameters of toxicity of a lipid A or lipid A-like compound and can yield false-positive results. However, these findings are not in conflict with the widespread use of the LAL assay for pyrogens in the pharmaceutical industry since a good correlation exists between LAL results and pyrogenicity when undegraded endotoxin is evaluated in parallel assays.

Animals↗
PubMed1984

Protective effect of muramyl dipeptide analogs in combination with trehalose dimycolate against aerogenic influenza virus and Mycobacterium tuberculosis infections in mice.

The effects of two aminobutyryl and four seryl analogs of the synthetic muramyl dipeptide (MDP) against aerosol infections with influenza virus and Mycobacterium tuberculosis were studied. Regardless of the MDP analog employed, there was no evidence that the resistance against viral and bacterial aerosol infections was enhanced in the treated mice. In parallel studies, significant protection against influenza virus and M. tuberculosis infections was induced by the combination of MDP or analogs with the mycobacterial glycolipid trehalose dimycolate (TDM). Resistance conferred by the MDP + TDM combination against influenza virus was present 1 week after pretreatment and could be abrogated by macrophage inhibitory agents silica, dextran sulfate, and carrageenan. Splenic cells from MDP + TDM-pretreated animals generated markedly enhanced levels of luminol-dependent chemiluminescence in response to influenza A and B viruses.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1983

Effects of mycobacterial fractions and muramyl dipeptide on the resistance of mice to aerogenic influenza virus infection.

The nonspecific protective effect in mice of pre-exposure to mycobacterial components and muramyl dipeptide three weeks before aerosol infection with influenza virus A/PR/8/34 (H1N1) was studied. Muramyl dipeptide, when combined with trehalose dimycolate and emulsified in an oil-in-water emulsion, conferred complete protection comparable to specific immunization with a high dose of formalin inactivated A/PR/8/34 influenza viral vaccine. Animals pre-exposed to muramyl dipeptide plus trehalose dimycolate showed a marked reduction in lung virus titres, an earlier clearance of detectable infectious virus, and an earlier onset of antibody production in comparison to control mice. Resistance to infection was also observed with BCG-cell wall skeleton combined with trehalose dimycolate and trehalose dimycolate alone when given as oil-in-water preparations. The route of administration of nonspecific stimulants was crucial. Only intravenous but not intradermal inoculation produced significant protection.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1983

Structural requirements of endotoxic glycolipid for antitumor and toxic activity.

Endotoxic glycolipids extracted from the polysaccharide heptose-less Re mutant of Salmonella typhimurium were hydrolyzed with alkaline and acid reagents. Treatment with hydroxylamine caused the liberation of all O-ester linked fatty acids and resulted in abrogation of the toxicity (lethality to chick embryos) and ability to regress tumors (line-10 tumors in strain 2 guinea pigs). Treatment with dilute sodium hydroxide caused partial removal of O-ester linked fatty acids without loss of these activities. Toxicity and tumor-regressive potency were retained after removal of 2-keto-3-deoxyoctonate (KDO) by exposing the glycolipids to sodium acetate solution at pH 4.5. The majority of the glycolipids of the endotoxic extracts were rendered non-toxic but retained antitumor activity when hydrolyzed with boiling 0.1 N hydrochloric acid, which split KDO and glycosidic phosphate from the glycolipid molecules. Non-toxic glycolipid fractions possessing antitumor activity were separated from the acid hydrolysate by means of preparative thin layer chromatography. It was concluded that glycosidic bound phosphate and at least a portion of the fatty acids of the lipid A moiety are essential for toxicity, but that this phosphate is not an essential structural feature for tumor-regression activity.

Animals↗
PubMed1983

Enhancement of macrophage-mediated tumor cell killing by bacterial outer membrane proteins (porins).

Various microbial products are known to influence the function of mouse peritoneal macrophages. Lipopolysaccharide (LPS) and certain lipid A-associated proteins are known to enhance the tumoricidal effects of macrophages. The purpose of this study was to determine whether porins (outer membrane proteins) of Salmonella typhimurium G30/C21 would influence the activity of macrophages from lipid A-responsive and -unresponsive mice. Porins, extracted by a combined sodium dodecyl sulfate-EDTA method from cell walls, were free of LPS as determined by Limulus amebocyte lysate assay and appeared as a band at approximately 36,000 molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In tumor cell killing assays done under LPS-free conditions, the porins in doses of 1 to 10 ng/ml enhanced the tumoricidal effect of macrophages from bacillus Calmette-Guérin-infected C3H/HeN or C3H/HeJ mice. Protein-free LPS enhanced the tumoricidal activity of macrophages from bacillus Calmette-Guérin-infected C3H/HeN but not C3H/HeJ mice. The tumoricidal-enhancing activity of protein-free LPS was blocked by the lipid A-binding antibiotic polymyxin B sulfate, but the effects of porins were not altered by the polymyxin B sulfate. These results suggest that porins, proteins known to alter membrane function, may alter macrophage function by interaction with macrophage membranes.

Animals↗
PubMed1982

Purification and structural determination of nontoxic lipid A obtained from the lipopolysaccharide of Salmonella typhimurium.

Endotoxin extracted from the heptose-less mutant of Salmonella typhimurium was hydrolyzed in 0.1 N HCl in methanol/water (1:1, v/v) at 100 degrees C to yield lipid A, which was then fractionated on a Sephadex LH-20 column to yield a major monophosphoryl lipid A fraction. The monophosphoryl lipid A was further fractionated by preparative thin layer chromatography. This process yielded three major bands (TLC-1, -3, and -5) and two minor bands (TLC-7 and -9). The purity of these fractions was established by ion exchange and reverse phase high performance liquid chromatography. The thin layer fractions were analyzed by fast atom bombardment mass spectrometry. TLC-1 and -3 gave molecular ions (M-H)- at m/e 1730 and 1716, respectively. Both of these fractions contained beta-hydroxymyristic, lauric, and 3-myristoxymyristic acids in O-acyl linkages. The molecular formula and Mr of TLC-1 are C95H179O22N2P and 1731.16; those of TLC-3 are C94H177O22N2P and 1717.15. TLC-1 was a methyl homolog of TLC-3. The major component of TLC-5 (C80H151O22N2P and Mr = 1506.99) gave a molecular ion at m/e 1506 and contained two beta-hydroxymyristic acids and a lauric acid in the O-acyl linkages. The major component of TLC-7 (C66H125O19N2P and Mr = 1280.83) and the single component of TLC-9 gave molecular ions at m/e 1280 and 1098, respectively. TLC-7 contained lauric and beta-hydroxymyristic acids in the O-acyl linkages. TLC-9 (C54H103O18N2P and Mr = 1098.69) contained a single O-acylated beta-hydroxymyristate group. TLC-1 and -3 were nontoxic in the chick embryo lethality test and regressed established tumors in the syngeneic guinea pigs.

Chromatography, High Pressure Liquid↗
PubMed1982

Induction of resistance to tuberculosis in mice with defined components of Mycobacteria and with some unrelated materials.

Factors contributing to protection against experimental tuberculosis have been studied with refined and well-characterized fractions from mycobacteria and with certain unrelated antigens. Mice were vaccinated intravenously with various combinations of materials presented on minute oil droplets in saline emulsion and were later challenged by aerosol. The minimal composition of an effective vaccine was P3 (a trehalose mycolate similar to cord factor) plus an antigen, which could be tuberculo-protein, or a low-molecular-weight tuberculin-active peptide, or unrelated antigen such as bovine serum albumin or bacterial endotoxin. Development of a hypersensitivity granuloma in the lungs appeared to be essential to protection in this laboratory model.

Animals↗