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Gangliosides and antitumor immunity.

To elucidate the possible influence on the host's immune defense of circulating gangliosides released from tumor cells, the effects of exogeneous gangliosides on the activities of some lymphocyte subpopulations were examined. The mono- and disialyllactosylceramides GM3 and GD3, which frequently are present in elevated amounts in sera of tumor-bearing hosts, were found to inhibit strongly the cytotoxicity of natural killer cells, to stimulate T-suppressor activity of peripheral blood lymphocytes, and to inhibit their phytohemagglutinin-induced blast transformation. All these effects may be linked to the ability of gangliosides to modulate the arachidonic acid cascade in lymphoid cells, which for the first time was demonstrated in the course of our studies. Possible mechanisms underlying the immunomodulatory effects of serum gangliosides as well as their role in the escape of tumor cells from immune surveillance and inhibition of the hosts immune system are discussed.

Animals↗

Striatal ganglioside levels in the rat following kainic acid lesions: comparison with Huntington's disease.

Ganglioside and DNA levels were estimated in the striatum of rats 10 days and 6 weeks after lesioning by intrastriatal injection of kainic acid. There was a moderate, 21-24% decrease of the ganglioside concentration per unit protein on the side of the lesion, which can be ascribed to the loss of the intrinsic striatal neurons following the injection of kainic acid. On the other hand, there was a 131 and 60% increase of DNA per unit protein in the kainate injected side 10 days and 6 weeks after the lesions, respectively; these changes apparently reflected the gliotic reaction brought about by the neurotoxin. Qualitatively similar findings--a decrease of ganglioside and an increase of DNA levels per unit protein--were also found in the brain of patients with Huntington's disease; however, as compared with the corresponding control material, the decrease of the ganglioside concentration was more pronounced in the striatum of Huntington's disease (by 38% in the caudate nucleus and by 46% in the putamen) than in the kainate lesioned rat striatum. This difference could be due to the different proportions of the intrinsic and extrinsic neuronal plasma membranes in the striatum of the two species; however, the possibility of a more generalized affection of neuronal plasma membranes in Huntington's disease may also be envisaged.

Animals↗

Gangliosides in vivo reduce diabetes incidence in non-obese diabetic mice.

Non-obese diabetic mice were treated daily with a mixture of gangliosides from day 30 until day 250 of life or until the mice became diabetic. Ganglioside treatment reduced diabetes incidence from 80-90% to 47% and from 20-30% to zero in female and male mice respectively. Gangliosides did not affect the frequency of perivasculitis. It is concluded that gangliosides can reduce diabetes incidence in non-obese diabetic mice.

Animals↗

The facilitating effect of gangliosides on the electrogenic (Na+/K+) pump and on the resistance of the membrane potential to hypoxia in neuromuscular preparation.

The effects have been investigated of a mixture of gangliosides from beef brain cortex (GM1, GD1a, GD1b and GT1) either added to the bathing medium or injected intraperitoneally on muscle fibres and nerve terminals in mouse diaphragm. The electrogenic (Na+/K+) pump activity of muscle fibres enriched with sodium was increased by 38% after 2-h pretreatment with gangliosides (5 X 10(-8) mol X 1(-1]. Muscles from animals treated with gangliosides did not show the substantial depolarization of the resting membrane potential (RMP) in K+-free solution (6 h) shown by control muscles. Further, treatment with gangliosides slowed the changes in muscle fibre RMP and frequency of the miniature end-plate potentials in oxygen deprived muscles.

Animals↗

Production and characterization of a monoclonal antibody (BBH5) directed to ganglioside lactone.

The occurrence of lactones in various ganglioside preparations has been clearly demonstrated, yet the natural occurrence of ganglioside lactones in cells and tissues has been the subject of long debate, since lactones can be formed readily during preparation of gangliosides. We now report the generation of monoclonal antibody (BBH5) that reacts specifically with lactones of disialogangliosides having the NeuAc2-8NeuAc2-3Gal sequence, but does not crossreact with the parent ganglioside. The specificity of the antibody resides on the first lactone ring between two sialic acid residues but not on the second lactone ring between sialic acid and galactose, as evidenced by reactivity with lactonized GD1b having the first lactone ring (L1), and by reactivity with lactonized polysialic acid homo-oligomers ([NeuAc alpha 2-8]nNeuAc). The sialic acid carboxyl involved in the lactone ring was unequivocally determined after ammonolysis followed by methylation and fast atom bombardment mass spectrometry. The antibody BBH5 thus provides a novel tool for studies of the natural occurrence of lactones in cells and tissues.

Antibodies, Monoclonal↗

Different binding capacities of influenza A and Sendai viruses to gangliosides from human granulocytes.

The structures of gangliosides from human granulocytes were elucidated by fast atom bombardment mass spectrometry and by gas chromatography/mass spectrometry as their partially methylated alditol acetates. In human granulocytes besides GM3 (II3Neu5Ac-LacCer), neolacto-series gangliosides (IV3Neu5Ac-nLcOse4Cer, IV6Neu5Ac-nLcOse4Cer and VI3Neu5Ac-nLcOse6Cer) containing C24:1, and to some extent C22:0; and C16:0 fatty acid in their respective ceramide portions, were identified as major components. In this study we demonstrate that gangliosides from human granulocytes, the second most abundant cells in peripheral blood, can serve as receptors for influenza viruses A/PR/8/34 (H1N1), A/X-31 (H3N2), and a parainfluenza virus Sendai virus (HNF1, Z-strain). Viruses were found to exhibit specific adhesion to terminal Neu5Ac alpha 2-3Gal and/or Neu5Ac alpha 2-6Gal sequences as well as depending on the chain length of ganglioside carbohydrate backbones from human granulocytes, these important effector cells which represent the first line of defence in immunologically mediated reactions.

Carbohydrate Sequence↗

A comparative assessment of TLC overlay technique and microwell adsorption assay in the examination of influenza A and Sendai virus specificities towards oligosaccharides and sialic acid linkages of gangliosides.

Influenza A and Sendai viruses bind to neolacto-series gangliosides isolated from human granulocytes. Differences in receptor specificity of influenza viruses A/PR/8/34 (H1N1), A/X-31 (H3N2), and parainfluenza Sendai virus (HNF1, Z-strain) were determined by two direct solid phase binding assays: the overlay technique, which combines high-resolution in the separation of gangliosides on thin-layer chromatograms with direct binding; and the microwell adsorption assay as a convenient binding assay which is performed in microtitre wells to estimate the avidity of binding to an isolated ganglioside. Both methods were applied for comparative binding studies. Viruses were found to exhibit specificity for oligosaccharides and sialic acids as well as for chain length of the neutral carbohydrate backbone, whereas differing fatty acids (C24:1 and C16:0) in the ceramide portion had no impact on virus adsorption. Terminal sialyloligosaccharides Neu5Ac alpha 2-3Gal beta 1-4Glc-R of GM3, and Neu5Ac alpha 2-3Gal beta 1-4GlcNAc-R as well as Neu5Ac alpha 2-6Gal beta 1-4GlcNAc-R of neolacto-series gangliosides with nLcOse4Cer and nLcOse6Cer backbone, exhibited significant specific receptor activity towards the different viruses. To compare the data revealed from both test systems, values of virus binding were ascertained by a non-parametric statistical approach based on rank correlation. The rank correlation coefficient rs was calculated according to Spearman from each virus binding towards GM3, IV3Neu5Ac-nLcOse4Cer, IV6Neu5Ac-nLcOse4Cer and VI3Neu5Ac-nLcOse6SCer. The rank correlation coefficients 0.74, 0.95 and 0.92, which were determined for A/PR/8/34 (H1N1), A/X-31 (H3N2) and Sendai virus (HNF1, Z-strain), respectively, indicated that both assays generate highly correlated experimental data.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗

Comparison of the glycolipid-binding specificities of cholera toxin and porcine Escherichia coli heat-labile enterotoxin: identification of a receptor-active non-ganglioside glycolipid for the heat-labile toxin in infant rabbit small intestine.

The binding specificities of cholera toxin and Escherichia coli heat-labile enterotoxin were investigated by binding of 125I-labelled toxins to reference glycosphingolipids separated on thin-layer chromatograms and coated in microtitre wells. The binding of cholera toxin was restricted to the GM1 ganglioside. The heat-labile toxin showed the highest affinity for GM1 but also bound, though less strongly, to the GM2, GD2 and GD1b gangliosides and to the non-acid glycosphingolipids gangliotetraosylceramide and lactoneotetraosylceramide. The infant rabbit small intestine, a model system for diarrhoea induced by the toxins, was shown to contain two receptor-active glycosphingolipids for the heat-labile toxin, GM1 ganglioside and lactoneotetraosylceramide, whereas only the GM1 ganglioside was receptor-active for cholera toxin. Preliminary evidence was obtained, indicating that epithelial cells of human small intestine also contain lactoneotetraosylceramide and similar sequences. By computer-based molecular modelling, lactoneotetraosylceramide was docked into the active site of the heat-labile toxin, using the known crystal structure of the toxin in complex with lactose. Interactions which may explain the relatively high toxin affinity for this receptor were found.

Animals↗

Isolation of three novel cholinergic neuron-specific gangliosides from bovine brain and their in vitro syntheses.

In the present study, three extremely minor but novel Chol-1 antigens, termed X1, X2, and X3 have been isolated from bovine brain gangliosides. Based on the results of sialidase degradation, TLC-immunostaining with anti-Chol-1 antibody and fast atom bombardment mass spectrometry, their chemical structures were identified as: III6NeuAc-GgOse4Cer (X1: GM1 alpha) III6NeuAc,II3NeuAc-GgOse4Cer (X2: GD1a alpha) III6NeuAc,II3NeuAc-NeuGc-GgOse4Cer (X3: GT1b alpha) The yields of GM1 alpha, GD1a alpha, and GT1b alpha, were approximately 150, 20, and 10 micrograms, respectively, from 10 g of the bovine brain ganglioside mixture. In conjunction with our previous observations, all gangliosides with anti-Chol-1 reactivity were found to contain a common sialyl alpha 2-6 N-acetylgalactosamine residue, indicating that this unique sialyl linkage is the specific antigenic determinant. We subsequently examined the biosynthesis of the three novel Chol-1 gangliosides using rat liver Golgi fraction as an enzyme source. The results showed that GM1 alpha, GD1a alpha, and GT1b alpha were synthesized from asialo-GM1, GM1a, and GD1b, respectively, by the action of a GalNAc alpha 2-6sialyltransferase.

Animals↗

Topographic studies of gangliosides of intact synaptosomes from rat brain cortex.

Gangliosides in the external surface of intact synaptosomes from rat brain cortex have been studied by oxidation of exposed galactose and galactosamine groups with galactose oxidase followed by reduction with labeled sodium borohydride. Purified synaptosomes were labeled, disrupted by osmotic shock, and the particulate components fractionated on diatrizoate to give four synaptosomal membrane fractions (A-D) and a mitochondrial pellet (E). Fractions A and B represent synaptosomal plasma membranes. When intact synaptosomes were labeled, the major portion of the total radioactivity incorporated into ganglioside fraction was found to be in GM1 3 species. With isolated membrane fractions little selectivity was seen: (1) more label was present compared to intact synaptosomes, and (2) zones corresponding to GM2, GM1, GD1a, GD1b were the major gangliosides labeled. The results confirm the conclusion that membrane fractions A and B are derived from the exposed synaptosome surface and also show that GM1 is the major ganglioside species available for enzyme oxidation at the surface.

Animals↗

Sulfated proteoglycans synthesized by Neuro 2a neuroblastoma cells: comparison between cells with and without ganglioside-induced neurites.

Mouse neuroblastoma Neuro 2a cells are known to extend neurite-like processes in response to gangliosides added to the culture medium. We compared the structural features of proteoglycans (PG) synthesized by conventional Neuro 2a cells with those of neurite-bearing cells. Two different proteoglycans labeled with [35S]sulfate, namely, chondroitin sulfate proteoglycan (CS-PG) and heparan sulfate proteoglycan (HS-PG), were found both in the cell layer and in the culture medium of the conventional cells. CS-PG isolated from the cell layer had a Kav value of 0.38 on Sepharose CL-6B, and had CS side chains with Mr of 27,000. HS-PG in the cell layer was slightly larger (Kav of 0.33) in terms of hydrodynamic size than CS-PG, and the apparent Mr of the heparan sulfate side chains was 10,000. The structural parameters of CS-PG and HS-PG isolated from the medium were almost identical to those of the PGs in the cell layer. In addition to these PGs, single-chain HS, with an average Mr of 2,500, was observed only in the cell layer and this component was the major sulfated component in the cell layers of both control and ganglioside treated cells. The neurite-bearing cells also synthesized both CS-PG and HS-PG which were very similar in hydrodynamic size to those synthesized by the conventional cells, but the size of HS side chains was greater. Radioactivity, as 35S, of each sulfated component from the ganglioside-treated culture seemed to be slightly less than that of the corresponding component from the control culture. These findings indicate that the marked morphological change in Neuro 2a cells, induced by gangliosides is not accompanied by major changes in the synthesis of PGs.

Animals↗

Maternal alcohol consumption and undernutrition in the rat: effects on gangliosides and their catabolizing enzymes in the CNS of the newborn.

Consumption of fifteen percent alcohol, during gestation did not cause any decrease in the total calorie or fluid intake of the rats maintained on normal dietary regimen. However, the alcohol consumption by gestating mothers resulted in a decreased contents of both DNA and protein in the CNS of the in utero alcohol exposed pups at birth. DNA content was also found to be less in the undernourished pups compared to the normal pups. On the other hand an increase in the total gangliosides and a decrease in the ganglioside catabolizing enzymes was observed in the brain and spinal cord of alcoholic pups at birth. However undernutrition resulted in a decrease in the content of total gangliosides both in brain and spinal cord. Maternal alcohol consumption and undernutrition had also resulted in an altered proportions of the individual ganglioside fractions.

Animals↗

Ganglioside and phospholipid composition of forebrain, cerebellum, and brain stem from adult and newborn rats.

The aim of this study was to elucidate whether sex or pregnancy state might affect the content and/or pattern of gangliosides from the forebrain, cerebellum and brain stem of rats. Adult male, mother (1-day after offspring) and nonpregnant rats of similar age were analyzed. Non-significant differences in ganglioside concentrations and patterns were found for the respective neural area of adult male and female rats except for a decrease in cerebellum and brain stem content from mothers and 12.0 months-old males, respectively. Thus, it seems that neither sex nor pregnancy hormones affect these parameters. By contrast, significant differences were found for pattern and ganglioside contents between adult (male and female) rats and newborns (1 day-old). Newborns showed a significant decrease in their forebrain (2.5-fold), cerebellum (2.0-fold) and brain stem (2.0-fold) ganglioside content when compared with adult (male and female) rats. Significant increases (p less than 0.001) were found in the phospholipid and cholesterol contents in the different brain areas in mothers versus their newborns. The phospholipid pattern also showed significant changes in all brain areas, with an increase (p less than 0.001) in phosphatidylethanolamine percentage in adult animals, among the main variations. An explanation for these facts is suggested.

Animals↗

Exogenous gangliosides may affect methylation mechanisms in neuronal cell cultures.

Primary neurons in culture from chick embryo cerebral hemispheres were treated with a mixture of gangliosides added to the growth medium (final concentration: 10(-5)M and 10(-8)M) from the 3rd to the 6th day in vitro. Under these conditions methylation processes measured with [3H] and [35S] methionine and [3H]ethanolamine as precursors showed an increased methylation of [3H]ethanolamine containing phospholipids, a correspondent increased conversion of these compounds to [3H]choline containing phospholipids, and a general increased methylation of trichloroacetic acid precipitable macromolecules containing labeled methionine. A small increase in protein synthesis was observed after incubation of neurons with [3H]- and [35S]methionine. This was confirmed after electrophoretic separation of a protein extract with increased 3H- and 35S-labeling in protein bands with moecular weights between 50 and 60 KDaltons. A protein band of about 55 KDaltons appeared to be preferentially labelled when [3H] methionine was the precursor. The treatment with gangliosides increased the incorporation of [methyl-3H] label after incubation of neurons with [3H] methionine, into total DNA and decreased that of total RNA. The treatment of neurons in culture with exogenous gangliosides hence affects differently methylation processes, a finding which may confirm the involvement of gangliosides on the intracellular mediation of neuronal information mechanisms.

Animals↗

Influence of exogenous gangliosides on the three-dimensional sprouting of goldfish retinal explants in vitro.

To investigate the 3-dimensional outgrowth of ganglion cells of normal and regenerating goldfish retina, retinal explants were cultured in a serum free 3-D fibrin matrix. Daily applications of exogenous gangliosides (GM1), injected either intraocularly (i.o.) or intraperitoneally (i.p.) had no significant effect on the sprouting activity of retinal explants prepared from lesion-activated goldfish whose corresponding optic nerve had been transected. However, in normal, unlesioned animals, a local i.o. injection of GM1 or mixed gangliosides led to a significant enhancement of the basal retinal sprouting activity as compared to controls, which were injected with a 0.9% NaCl solution. This ganglioside related stimulation was maximal after i.o. injection of low concentrations (3 micrograms/eye), didn't occur at high concentrations (30 micrograms/eye) and was similar to the response obtained after i.o. injection of NGF or insulin. I.o. injected phospholipids had no or a slightly inhibitory effect on the sprouting activity as compared to NaCl controls. Daily in vivo i.o. injections of the monoclonal antibody Q211, specifically recognizing c-pathway polysialogangliosides, led to a dose dependent inhibition of the in vitro sprouting of goldfish retina explants. In summary, these data suggest an involvement of gangliosides in the complex process of induction of neuronal sprouting.

Animals↗

[Analysis of gangliosides with special reference to milk].

Gangliosides are sialic acid containing lipid compounds of a very complex nature, which are involved in many physiological processes. Gangliosides are very important constituents of membrane material in animal tissue, where they occur at very low concentrations. Improved analytical procedures are therefore required to study their behaviour, their role in living systems and their isolation for further investigations. In this paper, all analytical methods which may be important in the analysis of gangliosides are summarized and discussed. These include extraction, purification, enrichment and chromatographic procedures. In bovine milk, three gangliosides of known structure are present. Their isolation, structure and analytical importance (buttermilk) are also reported.

Animals↗

Nuclear Overhauser effect investigation on GM1 ganglioside containing N-glycolyl-neuraminic acid (II3Neu5GcGgOse4Cer).

The conformational properties of the oligosaccharide chain of GM1 ganglioside containing N-glycolyl-neuraminic acid, beta-Gal-(1-3)-beta-GalNAc-(1-4)-[alpha-Neu5Gc-(2-3)]-beta-Gal- (1-4)1-4)-beta-Glc-(1-1)-Cer, were studied through NMR nuclear Overhauser effect investigations on the monomeric ganglioside in dimethylsulfoxide, and on mixed micelles of ganglioside and dodecylphosphocholine in water. Several interresidual contacts for the trisaccharide core -beta- GalNAc-(1-4)-[alpha-Neu5Gc-(2-3)]-beta-Gal- were found to fix the relative orientation of the three saccharides, while the glycosidic linkage of the terminal beta-Gal- was found to be quite mobile as the beta-Gal-(1-3)-beta-GalNAc- disaccharide exists in different conformations. These results are similar to those found for two GM1 gangliosides containing N-acetyl-neuraminic acid and neuraminic acid [1].

Carbohydrate Conformation↗

Involvement of the acyl chain of ceramide in carbohydrate recognition by an anti-glycolipid monoclonal antibody: the case of an anti-melanoma antibody, M2590, to GM3-ganglioside.

The effect of the chain length of the fatty acid residue of the ceramide moiety of ganglioside GM3 on the binding ability of monoclonal antibody M2590, which is specific for the carbohydrate structure of GM3-ganglioside, was examined by means of a direct binding assay on thin layer chromatography plates (TLC immunostaining) and a quantitative enzyme-linked immunosorbent assay (ELISA). Derivatives of GM3 with a long fatty acid chain reacted with the M2590 antibody, but those with a short fatty acid chain showed no reaction in either assay system. These results suggested that the acyl fatty acid moiety of the ganglioside played an important role in the formation or maintenance of the antigenic structure of the carbohydrate moiety of the ganglioside.

Animals↗