Biological activities of lipopolysaccharides from Pectinatus cerevisiophilus

Abstract A procedure is described in which the protein crystals produced by Bacillus thuringiensis var. israelensis were solubilized in 50 mM NaOH with 10 mM EDTA at pH 11.7. This solubilization procedure gave protein gel profiles identical with those for intact crystals while maintaining full biological activity in the form of erythrocyte lysis capability. Crystals with and without protease activity were equally toxic to Aedes aegypti larvae.     

Biological and serological characterization of Campylobacter jejuni lipopolysaccharides with deviating core and lipid A structures

Abstract Lipopolysaccharides from Campylobacter jejuni were tested for their ability to induce toxic lethality in galactosamine-sensitized mice, pyrogenicity in rabbits and tumour necrosis factor (TNF) secretion from mouse peritoneal macrophages. Compared with those of Salmonella LPS, lethal toxicity was 50% lower, pyrogenicity was 30- to 50-fold lower, and ability to induce TNF was 100-fold lower. C. jejuni LPS and lipid A exhibited higher phase-transition temperatures than those of Salmonella preparations, and thus the former have lower fluidity at 37°C. This lower fluidity of acyl chains may influence the biological activities of C. jejuni LPS, but acyl chain characteristics and diaminoglucose replacing glucosamine in the hydrophilic lipid A backbone may also influence the supramolecular structure of lipid A, thereby affecting biological activities. Although diaminoglucose is present in the backbone of C. jejuni lipid A, antigenically the latter resembled classical lipid A of the Enterobacteriaceae when tested with anti-lipid A antibodies. Chemical investigations suggested the presence of glucuronic acid in an acid labile linkage in the inner core region, thus producing a structurally unusual region in C. jejuni LPS.     

The interactions of cartilage proteoglycans with collagens are determined by their structures.

In the present work, the interaction of aggrecan, decorin and biglycan isolated from pig laryngeal cartilage and of the three squid cartilage proteoglycans with collagen type I and II was studied. The interaction was examined under conditions allowing the formation of collagen fibrils. It was found that biglycan interacted strongly with collagen type II and not with type I and the interaction seemed to proceed exclusively through its core proteins. Decorin interacted with collagen type I but not with type II. Aggrecan interacted very poorly with both collagen types. The two squid proteoglycans of large size, D1D1A and D1D2, interacted only with collagen type I through both glycosaminoglycans and core proteins. The third squid proteoglycan of small size, D1D1B, interacted poorly only with collagen type I. The results suggested that the interactions of cartilage proteoglycans with collagen were mainly due to the primary structure of both molecules, and would contribute to the maintenance of the integrity of the tissue. The biochemical significance of these interactions might be more critical in aged vertebrate cartilage, where loss of aggrecan and increase of the small proteoglycans was observed, a large proportion of which is found in the extracellular matrix free of glycosaminoglycan chains.     

Biological activities of chemically synthesized partial structure analogues of lipid A

Analogues of the nonreducing sugar part of lipid A were chemically synthesized and tested for biological activities such as Limulus amebocyte lysate gelation, interferon- and tumor necrosis factor-induction, lethal toxicity in galactosamine-sensitized mice, and pyrogenicity. A 4-O-monophosphorylglucosamine derivative possessing 2-N-3-tetradecanoyl-oxytetradecanoyl and 3-O-tetradecanoyl groups (GLA-27) exhibited all activities tested except for pyrogenicity. Alteration of the acyl substituents or dephosphorylation as well as acylation or phosphorylation of the 6-OH caused most activities of GLA-27 to diminish or disappear altogether. On the other hand, the biological activities expressed by GLA-27 were not significantly affected even when the glucosamine backbone was changed to 1-deoxy type, epimer type at C-3 (allose form), or 3-amino type. These results indicate that the acyl substituents and the phosphorylation positions rather than the backbone structures in these partial structure analogues of lipid A affect the expression of biological activities of endotoxin. The results also clearly indicate that some biological activities of endotoxin can be expressed separately from pyrogenicity.     

Chemical structure of the lipid A component of lipopolysaccharides from Fusobacterium nucleatum.

The lipid A component of lipopolysaccharides from Fusobacterium nucleatum Fev 1 consists of beta-1',6-linked D-glucosamine disaccharides, which carry two phosphate groups: one in glycosidic and one in ester linkage. The amino groups of the glucosamine disaccharides are substituted by D-3-hydroxyhexadecanoic acid. The hydroxyl groups of the disaccharide backbone are acylated by tetradecanoic, hexadecanoic, and D-3-hydroxytetradecanoic acids. Part of the ester-bound D-3-hydroxytetradecanoic acid is 3-O-substituted by tetradecanoic acid. Whereas a similar pattern of fatty acids was detected in lipopolysaccharides from two other F. nucleatum strains, the amide-bound fatty acid in F. varium and F. mortiferum was D-3-hydroxytetradecanoic acid. The chemical relationships of lipid A from Fusobacteria and other gram-negative bacteria are discussed.     

Biological activities of chemically synthesized analogues of the nonreducing sugar moiety of lipid A

Adriamycin-Fe3+ complex catalyzes the formation of hydroxyl radical from hydrogen peroxide but the DNA-adriamycin-iron ternary complex is much more effective. 11-Deoxyadriamycin, which shows no spectral evidence of complex formation with iron, was ineffective. The generation of hydroxyl radical by adriamycin-Fe3+ complex in the presence of DNA correlates with its ability to cleave DNA. Hydroxyl radicals are thus implicated as the reactive oxygen species involved in the DNA damage caused by the adriamycin-Fe3+ complex.     

A possible correlation between histological changes in regional subcutaneous tissue induced by bacterial lipopolysaccharides and their adjuvant activities

Previously it was demonstrated that Klebsiella pneumoniae O3 lipopolysaccharide (KO3 LPS) exhibited much stronger adjuvant action on antibody response to subcutaneously (s.c.) injected sheep red blood cells or deaggregated bovine serum albumin than did other kinds of LPS, the R-form LPS lacking the O-specific polysaccharide chain of KO3 LPS (R-LPS), and the lipid A fractionated from KO3 LPS. We compared histological changes in the regional subcutaneous tissues of mice injected subcutaneously (s.c.) with KO3 LPS, the lipid A, and R-LPS. At the early stage after injection, KO3 LPS induced the infiltration of a large number of inflammatory cells, mainly polymorphonuclear leukocytes (PMN), at the site of injection. Neither R-LPS nor the lipid A induced the accumulation of PMN so much as KO3 LPS did. When injected s.c. with LPS from Escherichia coli O111 (EO111 LPS) and O55 (EO55 LPS), and Salmonella enteritidis (Sent LPS), the appearance of PMN at the regional site was much less than KO3 LPS. KO3 LPS could accumulate more 51Cr-labeled leukocytes at the injection site than EO111 LPS and Sent LPS. Administration of acetylsalicylic acid, which can inhibit leukocyte migration in inflammatory lesions, suppressed its adjuvant action. It was therefore suggested that the strong adjuvant action of KO3 LPS in s.c. injection might be dependent on its potent capability of accumulating PMN at the regional subcutaneous tissue. Furthermore, at the late stage after injection, the formation of several lymphoid follicles at the regional site was seen only in mice injected with KO3 LPS. It might be also related to the strong adjuvant action of KO3 LPS.     

Characterization of lipid A and polysaccharide moieties of the lipopolysaccharides from Vibrio cholerae.

Lipid A and polysaccharide moieties obtained by mild acid hydrolysis of the lipopolysaccharides from Vibrio cholerae 569 B (Inaba) and Vibrio el-tor (Inaba) were characterized. Heterogeneity of lipid A fractions was indicated by t.l.c. and by gel filtration of the de-O-acylated products from mild alkaline methanolysis of the lipids. Presumably lipid A contains a glucosamine backbone, and the fatty acids are probably bound to the hydroxyl and amino groups of glucosamine residues. Approximately equal amounts of fatty acids C16:0, C18:1 and 3-hydroxylauric acid were involved in ester linkages, but 3-hydroxymyristic acid was the only amide-linked fatty acid. Sephadex chromatography of the polysaccharide moiety showed the presence of a high-molecular-weight heptose-free fraction and a low-molecular-weight heptose-containing fraction. Haemagglutination-inhibition assays of these fractions showed the heptose-free fraction to be an O-specific side-chain polysaccharide, whereas the heptose-containing fraction was the core polysaccharide region of the lipopolysaccharides. Identical results were obtained for both organisms.     

Structural studies on the lipid A component of enterobacterial lipopolysaccharides by laser desorption mass spectrometry. Location of acyl groups at the lipid A backbone

In the present paper laser desorption mass spectrometry (LDMS) was applied to dephosphorylated free lipid A preparations obtained from lipopolysaccharides of Re mutants of Salmonella minnesota, Escherichia coli and Proteus mirabilis. The purpose of this study was to elucidate the location of (R)-3-hydroxytetradecanoic acid and 3-O-acylated (R)-3-hydroxytetradecanoic acid residues which are bound to amino and hydroxyl groups of the glucosamine disaccharide backbone of lipid A. Based on the previous finding from biochemical analyses that the amino group of the nonreducing glucosamine residue (GlcN II) of the backbone carries, in S. minnesota and E. coli, 3-dodecanoyloxytetradecanoic acid and, in P. mirabilis, 3-tetradecanoyloxytetradecanoic acid, a self-consistent interpretation of the LDMS was possible. It was found that: (a) in all three lipids A GlcN II is, besides the amide-linked 3-acyloxyacyl residue, substituted by ester-linked 3-tetradecanoyloxytetradecanoic acid; (b) the reducing glucosamine (GlcN I) is substituted by ester-linked 3-hydroxytetradecanoic acid; (c) the amino group of GlcN I carries a 3-hydroxytetradecanoic acid which is non-acylated in E. coli and which is partially acylated by hexadecanoic acid in S. minnesota and P. mirabilis. In lipids A which were obtained from the P. mirabilis Re mutant grown at low temperature (12 degrees C) LDMS analysis revealed that specifically the one fatty acid bound to the 3-hydroxyl group of amide-linked 3-hydroxytetra-decanoic acid at GlcN II is positionally replaced by delta 9-hexadecenoic acid (palmitoleic acid). It appears, therefore, that enterobacterial lipids A resemble each other in that the 3-hydroxyl groups of the two 3-hydroxytetradecanoic acid residues linked to GlcN II are fully acylated, while those of the two 3-hydroxytetradecanoic acid groups attached to GlcN I are free or only partially substituted.     

Biological activities of analogues of lipid A based chemically on the revised structural model. Comparison of mediator-inducing, immunomodulating and endotoxic activities

Lipid A analogues were chemically synthesized based on the model structure recently revised, and biological activities of the analogues were tested. The analogue, (beta-1,6)-linked glucosamine disaccharide carrying ester-bound 3-hydroxytetradecanoic acids at 3 and 3' position of reducing and nonreducing glucosamine in addition to amide-bound 3-hydroxytetradecanoic acids and glycosidic-linked and ester-linked phosphate groups, showed much stronger activities for mediator inducing and immunomodulating as well as endotoxic activities than those exhibited by the previously synthesized analogues based on the old model. Among the activities tested, induction of interferon and tumor necrosis factor as well as mitogenicity, adjuvanticity and pyrogenicity were, however, not expressed so strongly as natural lipid A used as controls. In contrast, the analogue exhibited comparable activities to those of control lipid A in the test of lethal toxicity to mice and gelating activity of Limulus amebocyte lysate. Other synthetic analogues carrying a phosphate group showed comparable, slightly stronger or weaker activities depending on the test, but nonphosphorylated analogue exhibited no apparent or only very weak activities.     

Mutual modulation of sphingomyelinase and phospholipase A2 activities against mixed lipid monolayers by their lipid intermediates and glycosphingolipids

Sphingomyelinase activity against pure sphingomyelin monolayers is constant up to a surface pressure of 18 mN/m and falls above it. Sphingomyelinase- and phospholipase A₂-mediated phosphohydrolytic pathways are mutually modulated by the presence of their respective substrates and products. At 15 mN/ m non-substrate lipids such as ceramide at a mole fraction of 0·1 in mixed films with the pure substrate, inhibit the sphingomyelinase activity. Ganglioside GM1, another ceramide-containing complex sphingolipid, also inhibits sphingomyelinase activity, while a chemically related glycosphingolipid such as asialo-GM1 has no effect. The activity is unaltered by dipalmitoylphosphatidylcholine and by an equimolar mixture of its products of hydrolysis by phospholipase A₂, fatty acid and lysoderivative, but it is inhibited by only one of them or by dilauroylphosphatidylcholine. Phospholipase A₂ is inhibited by sphingomyelin, and activated by ceramide and by palmitic acid, one of the products of its own phosphohydrolytic reaction.     

Structural characterization of the lipid A component of Helicobacter pylori rough- and smooth-form lipopolysaccharides.

The chemical structure of free lipid A isolated from rough- and smooth-form lipopolysaccharides (R-LPS and S-LPS, respectively) of the human gastroduodenal pathogen Helicobacter pylori was elucidated by compositional and degradative analysis, nuclear magnetic resonance spectroscopy, and mass spectrometry. The predominant molecular species in both lipid A components are identical and tetraacylated, but a second molecular species which is hexaacylated is also present in lipid A from S-LPS. Despite differences in substitution by acyl chains, the hydrophilic backbone of the molecules consisted of beta(1,6)-linked D-glucosamine (GlcN) disaccharide 1-phosphate. Because of microheterogeneity, nonstoichiometric amounts of ethanolamine-phosphate were also linked to the glycosidic hydroxyl group. In S-LPS, but not in R-LPS, the hydroxyl group at position 4' was partially substituted by another phosphate group. Considerable variation in the distribution of fatty acids on the lipid A backbone was revealed by laser desorption mass spectrometry. In tetraacyl lipid A, the amino group of the reducing GlcN carried (R)-3-hydroxyoctadecanoic acid (position 2), that of the nonreducing GlcN carried (R)-3-(octadecanoyloxy)octadecanoic acid (position 2'), and ester-bound (R)-3-hydroxyhexadecanoic acid was attached at position 3. Hexaacyl lipid A had a similar substitution by fatty acids, but in addition, ester-bound (R)-3-(dodecanoyloxy)hexadecanoic acid or (R)-3(tetradecanoyloxy)hexadecanoic acid was attached at position 3'. The predominant absence of ester-bound 4'-phosphate and the presence of tetraacyl lipid A with fatty acids of 16 to 18 carbons in length differentiate H. pylori lipid A from that of other bacterial species and help explain the low endotoxic and biological activities of H. pylori LPS.