Gangliosides of human, cat, and rabbit spinal cords and cord myelin

Vibrio-binding gangliosides in fish intestinal tracts

It has been clarified that pathogens bind to glycosphingolipid (GSL) receptors in mammals, but there have been very few reports on pathogen-binding GSLs in fish. Vibrios are facultative anaerobic bacteria ubiquitous in marine and brackish environments. They are members of the normal intestinal microflora of healthy fish, but some species can cause a disease called vibriosis in fish and shellfish when the hosts are physiologically or immunologically weakened. The adherence of vibrios to host intestinal tracts is a significant event not only for survival and growth but also in terms of pathogenicity. We show in this mini-review that sialic acid-containing GSLs (gangliosides), GM4 and GM3, are receptors to which vibrios adhere to epithelial cells in the intestinal tract of fish. We also describe the enzymes responsible for synthesizing these Vibrio-binding gangliosides in fish.

Axonopathy and Reduction of Membrane Resistance: Key Features in a New Murine Model of Human GM1-Gangliosidosis

G_M1-gangliosidosis is caused by a reduced activity of β-galactosidase (Glb1), resulting in intralysosomal accumulations of G_M1. The aim of this study was to reveal the pathogenic mechanisms of G_M1-gangliosidosis in a new Glb1 knockout mouse model. Glb1^−/− mice were analyzed clinically, histologically, immunohistochemically, electrophysiologically and biochemically. Morphological lesions in the central nervous system were already observed in two-month-old mice, whereas functional deficits, including ataxia and tremor, did not start before 3.5-months of age. This was most likely due to a reduced membrane resistance as a compensatory mechanism. Swollen neurons exhibited intralysosomal storage of lipids extending into axons and amyloid precursor protein positive spheroids. Additionally, axons showed a higher kinesin and lower dynein immunoreactivity compared to wildtype controls. Glb1^−/− mice also demonstrated loss of phosphorylated neurofilament positive axons and a mild increase in non-phosphorylated neurofilament positive axons. Moreover, marked astrogliosis and microgliosis were found, but no demyelination. In addition to the main storage material G_M1, G_A1, sphingomyelin, phosphatidylcholine and phosphatidylserine were elevated in the brain. In summary, the current Glb1^−/− mice exhibit a so far undescribed axonopathy and a reduced membrane resistance to compensate the functional effects of structural changes. They can be used for detailed examinations of axon–glial interactions and therapy trials of lysosomal storage diseases.

Increasing acetyl-CoA metabolism attenuates injury and alters spinal cord lipid content in mice subjected to experimental autoimmune encephalomyelitis

Acetate supplementation increases brain acetyl-CoA metabolism, alters histone and non-histone protein acetylation, increases brain energy reserves, and is anti-inflammatory and neuroprotective in rat models of neuroinflammation and neuroborreliosis. To determine the impact acetate supplementation has on a mouse model of multiple sclerosis, we quantified the effect treatment had on injury progression, spinal cord lipid content, phospholipase levels, and myelin structure in mice subjected to experimental autoimmune encephalomyelitis (EAE). EAE was induced by inoculating mice with a myelin oligodendrocyte glycoprotein peptide fragment (MOG_35-55 ), and acetate supplementation was maintained with 4 g/kg glyceryl triacetate by a daily oral gavage. Acetate supplementation prevented the onset of clinical signs in mice subject to EAE compared to control-treated mice. Furthermore, acetate supplementation prevented the loss of spinal cord ethanolamine and choline glycerophospholipid and phosphatidylserine in mice subjected to EAE compared to EAE animals treated with water. Treatment increased saturated and monounsaturated fatty acid levels in phosphatidylserine compared to controls suggesting that acetate was utilized to increase spinal cord fatty acid content. Also, acetate supplementation prevented the loss of spinal cord cholesterol in EAE animals but did not change cholesteryl esters. Treatment significantly increased GD3 and GD1a ganglioside levels in EAE mice when compared to EAE mice treated with water. Treatment returned levels of phosphorylated and non-phosphorylated cytosolic phospholipase A₂ (cPLA₂ ) levels back to baseline and based on FluoroMyelin™ histochemistry maintained myelin structural characteristics. Overall, these data suggest that acetate supplementation may modulate lipid metabolism in mice subjected to EAE.

Serological study using glycoarray for detecting antibodies to glycolipids and glycolipid complexes in immune-mediated neuropathies

We performed a serological investigation using glycoarray in Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and multifocal motor neuropathy (MMN). Antibodies to 10 glycolipids and 45 glycolipid complexes were tested. Anti-GM1/sulfatide and anti-GA1/sulfatide IgG antibodies were common in GBS (20.0% and 19.0%, respectively). Anti-GQ1b/sulfatide IgG antibody was detected in 14.0% of GBS patients. IgG antibodies to antigens containing GQ1b were significantly correlated with ophthalmoplegia in GBS (p<0.01). IgM antibodies to antigens containing GM1 or GalNAc-GD1a were in 50% and 37.5% of MMN patients, respectively. Glycoarray is efficient for detecting antibodies against numerous glycolipid complexes in immune-mediated neuropathies.

Lipidomics of human brain aging and Alzheimer's disease pathology

Lipids stimulated and favored the evolution of the brain. Adult human brain contains a large amount of lipids, and the largest diversity of lipid classes and lipid molecular species. Lipidomics is defined as "the full characterization of lipid molecular species and of their biological roles with respect to expression of proteins involved in lipid metabolism and function, including gene regulation." Therefore, the study of brain lipidomics can help to unravel the diversity and to disclose the specificity of these lipid traits and its alterations in neural (neurons and glial) cells, groups of neural cells, brain, and fluids such as cerebrospinal fluid and plasma, thus helping to uncover potential biomarkers of human brain aging and Alzheimer disease. This review will discuss the lipid composition of the adult human brain. We first consider a brief approach to lipid definition, classification, and tools for analysis from the new point of view that has emerged with lipidomics, and then turn to the lipid profiles in human brain and how lipids affect brain function. Finally, we focus on the current status of lipidomics findings in human brain aging and Alzheimer's disease pathology. Neurolipidomics will increase knowledge about physiological and pathological functions of brain cells and will place the concept of selective neuronal vulnerability in a lipid context.

AAV-mediated gene delivery in a feline model of Sandhoff disease corrects lysosomal storage in the central nervous system

Sandhoff disease (SD) is an autosomal recessive neurodegenerative disease caused by a mutation in the gene for the β-subunit of β-N-acetylhexosaminidase (Hex), resulting in the inability to catabolize ganglioside GM2 within the lysosomes. SD presents with an accumulation of GM2 and its asialo derivative GA2, primarily in the central nervous system. Myelin-enriched glycolipids, cerebrosides and sulfatides, are also decreased in SD corresponding with dysmyelination. At present, no treatment exists for SD. Previous studies have shown the therapeutic benefit of adeno-associated virus (AAV) vector-mediated gene therapy in the treatment of SD in murine and feline models. In this study, we treated presymptomatic SD cats with AAVrh8 vectors expressing feline Hex in the thalamus combined with intracerebroventricular (Thal/ICV) injections. Treated animals showed clearly improved neurologic function and quality of life, manifested in part by prevention or attenuation of whole-body tremors characteristic of untreated animals. Hex activity was significantly elevated, whereas storage of GM2 and GA2 was significantly decreased in tissue samples taken from the cortex, cerebellum, thalamus, and cervical spinal cord. Treatment also increased levels of myelin-enriched cerebrosides and sulfatides in the cortex and thalamus. This study demonstrates the therapeutic potential of AAV for feline SD and suggests a similar potential for human SD patients.

The effect of heme oxygenase on ganglioside redistribution within hepatocytes in experimental estrogen-induced cholestasis

Cholestasis is characterized by the elevation of serum total bile acids (TBA), which leads to the production of both free radicals and oxidative stress. Although they do not share the same mechanisms, membrane glycosphingolipids (GSL) and the antioxidant enzyme heme oxygenase-1 (HMOX1) both act against the pro-oxidative effect of TBA. The aim of the study was to assess the role of HMOX on GSL redistribution and composition within hepatocytes in the rat model of estrogen-induced cholestasis. Compared to the controls, an increase of total gangliosides in the liver homogenates of the cholestatic group (P=0.001) was detected; further, it paralleled along with the activation of their biosynthetic b-branch pathway (P<0.01). These effects were partially prevented by HMOX activation. Cholestasis was accompanied by a redistribution of GM1 ganglioside from the cytoplasm to the sinusoids; while HMOX activation led to the retention of GM1 in the cytoplasm (P=0.014). Our study shows that estrogen-induced cholestasis is followed by changes in the synthesis and/or distribution of GSL. These changes are not only triggered by the detergent power of accumulated TBA, but also by their pro-oxidant action. Increases in the antioxidant defenses might represent an important supportive therapeutic measure for patients with cholestatic liver disease.

Autoimmune T-cell reactivity to myelin proteolipids and glycolipids in multiple sclerosis

Central nervous system (CNS) myelin, the likely major target of autoimmune attack in multiple sclerosis (MS), contains a number of unique components that are potential targets of the attack. Two classes of molecules that are greatly enriched in CNS myelin compared to other parts of the body are certain types of proteolipids and glycolipids. Due to the hydrophobic nature of both of these classes of molecules, they present challenges for use in immunological assays and have therefore been somewhat neglected in studies of T-cell reactivity in MS compared to more soluble molecules such as the myelin basic proteins and the extracellular domain of myelin oligodendrocyte glycoprotein. This review firstly looks at the makeup of CNS myelin, with an emphasis on proteolipids and glycolipids. Next, a retrospective of what is known of T-cell reactivity directed against proteolipids and glycolipids in patients with MS is presented, and the implications of the findings are discussed. Finally, this review considers the question of what would be required to prove a definite role for autoreactivity against proteolipids and glycolipids in the pathogenesis of MS.

Structural reevaluation of Streptococcus pneumoniae Lipoteichoic acid and new insights into its immunostimulatory potency

Streptococcus pneumoniae is a Gram-positive human pathogen with a complex lipoteichoic acid (pnLTA) structure. Because the current structural model for pnLTA shows substantial inconsistencies, we reinvestigated purified and, more importantly, O-deacylated pnLTA, which is most suitable for NMR spectroscopy and electrospray ionization-MS spectrometry. We analyzed pnLTA of nonencapsulated pneumococcal strains D39Δcps and TIGR4Δcps, respectively. The data obtained allowed us to (re)define (i) the position and linkage of the repeating unit, (ii) the putative α-GalpNAc substitution at the ribitiol 5-phosphate (Rib-ol-5-P), and (iii) the length of (i.e. the number of repeating units in) the pnLTA chain. We here also describe for the first time that the terminal sugar residues in the pnLTA (Forssman disaccharide; α-D-GalpNAc-(1→3)-β-D-GalpNAc-(1→)), responsible for the cross-reactivity with anti-Forssman antigen antibodies, can be heterogeneous with respect to its degree of phosphorylcholine substitution in both O-6-positions. To assess the proinflammatory potency of pnLTA, we generated a (lipopeptide-free) Δlgt mutant of strain D39Δcps, isolated its pnLTA, and showed that it is capable of inducing IL-6 release in human mononuclear cells, independent of TLR2 activation. This finding was quite in contrast to LTA of the Staphylococcus aureus SA113Δlgt mutant, which did not activate human mononuclear cells in our experiments. Remarkably, this is also contrary to various other reports showing a proinflammatory potency of S. aureus LTA. Taken together, our study refines the structure of pnLTA and indicates that pneumococcal and S. aureus LTAs differ not only in their structure but also in their bioactivity.

High-performance thin-layer chromatography/mass spectrometry for the analysis of neutral glycosphingolipids

This mini-review summarizes the protocol we have developed for the analysis of neutral glycosphingolipids (GSLs) by high-performance thin layer chromatography (HPTLC)-mass spectrometry (MS). We also present results obtained using this glycolipidomic approach to study neutral GSLs from mouse kidney, spleen, and small intestine. Finally, we discuss what is required for further development of this method, as well as what is expected for the future of glycolipid biology.

Advances on the compositional analysis of glycosphingolipids combining thin-layer chromatography with mass spectrometry

Glycosphingolipids (GSLs), composed of a hydrophilic carbohydrate chain and a lipophilic ceramide anchor, play pivotal roles in countless biological processes, including infectious diseases and the development of cancer. Knowledge of the number and sequence of monosaccharides and their anomeric configuration and linkage type, which make up the principal items of the glyco code of biologically active carbohydrate chains, is essential for exploring the function of GSLs. As part of the investigation of the vertebrate glycome, GSL analysis is undergoing rapid expansion owing to the application of novel biochemical and biophysical technologies. Mass spectrometry (MS) takes part in the network of collaborations to further unravel structural and functional aspects within the fascinating world of GSLs with the ultimate aim to better define their role in human health and disease. However, a single-method analytical MS technique without supporting tools is limited yielding only partial structural information. Because of its superior resolving power, robustness, and easy handling, high-performance thin-layer chromatography (TLC) is widely used as an invaluable tool in GSL analysis. The intention of this review is to give an insight into current advances obtained by coupling supplementary techniques such as TLC and mass spectrometry. A retrospective view of the development of this concept and the recent improvements by merging (1) TLC separation of GSLs, (2) their detection with oligosaccharide-specific proteins, and (3) in situ MS analysis of protein-detected GSLs directly on the TLC plate, are provided. The procedure works on a nanogram scale and was successfully applied to the identification of cancer-associated GSLs in several types of human tumors. The combination of these two supplementary techniques opens new doors by delivering specific structural information of trace quantities of GSLs with only limited investment in sample preparation.

Absence of oligodendroglial glucosylceramide synthesis does not result in CNS myelin abnormalities or alter the dysmyelinating phenotype of CGT-deficient mice

To examine the function of glycosphingolipids (GSLs) in oligodendrocytes, the myelinating cells of the central nervous system (CNS), mice were generated that lack oligodendroglial expression of UDP-glucose ceramide glucosyltransferase (encoded by Ugcg). These mice (Ugcg(flox/flox);Cnp/Cre) did not show any apparent clinical phenotype, their total brain and myelin extracts had normal GSL content, including ganglioside composition, and myelin abnormalities were not detected in their CNS. These data indicate that the elimination of gangliosides from oligodendrocytes is not detrimental to myelination. These mice were also used to asses the potential compensatory effect of hydroxyl fatty acid glucosylceramide (HFA-GlcCer) accumulation in UDP-galactose:ceramide galactosyltransferase (encoded by Cgt, also known as Ugt8a) deficient mice. At postnatal day 18, the phenotypic characteristics of the Ugcg(flox/flox);Cnp/Cre;Cgt(-/-) mutants, including the degree of hypomyelination, were surprisingly similar to that of Cgt(-/-) mice, suggesting that the accumulation of HFA-GlcCer in Cgt(-/-) mice does not modify their phenotype. These studies demonstrate that abundant, structurally intact myelin can form in the absence of glycolipids, which normally represent over 20% of the dry weight of myelin.

Zebrafish and mouse alpha2,3-sialyltransferases responsible for synthesizing GM4 ganglioside

We have previously reported that fish pathogens causing vibriosis specifically adhere to GM4 on the epithelial cells of fish intestinal tracts (Chisada, S., Horibata, Y., Hama, Y., Inagaki, M., Furuya, N., Okino, N., and Ito, M. (2005) Biochem. Biophys. Res. Commun. 333, 367-373). To identify the gene encoding the enzyme for GM4 synthesis in the fish intestinal tract, a phylogenetic tree of vertebrate ST3GalVs, including Danio rerio and Oryzias latipes, was generated in which two putative subfamilies of fish ST3GalVs were found. Two putative ST3GalVs of zebrafish (zST3GalV-1 and -2), each belonging to different subfamilies, were cloned from the zebrafish cDNA library. Interestingly, zST3GalV-1 synthesized GM3 (NeuAcalpha2-3Galbeta1-4Glcbeta1-1'Cer) but not GM4, whereas zSTGalV-2 synthesized both gangliosides in vitro when expressed in CHO-K1 and RPMI1846 cells. Flow cytometric analysis using anti-GM4 antibody revealed that the transformation of RPMI1846 cells with zST3GalV-2 but not zST3GalV-1 cDNA increased the cell-surface expression of GM4. Whole mount in situ hybridization showed that the zST3GalV-2 transcript was strongly expressed in the gastrointestinal tract, whereas zST3GalV-1 was expressed in the brain and esophagus but not gastrointestinal tract in 3-day post-fertilization embryos. It has long been a matter of controversy which enzyme is responsible for the synthesis of GM4 in mammals. We found that three isoforms of mouse ST3GalV (mST3GalV) having different N-terminal sequences can synthesize GM4 as well as GM3 when expressed in RPMI1846 and CHO-K1 cells. Furthermore, mST3GalV knock-out mice were found to lack GM4 synthase activity and GM4 in contrast to wild-type mice. These results clearly indicate that zST3GalV-2 and mST3GalV are the enzymes responsible for the synthesis of GM4 in zebrafish and mice, respectively.

Direct Analysis of Silica Gel Extracts from Immunostained Glycosphingolipids by Nanoelectrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry

A combined strategy of preparative high-performance thin-layer chromatography overlay assay and mass spectrometry was established for the structural characterization of immunostained glycosphingolipids (GSLs) in silica gel extracts. Crude chloroform/methanol/water (30/60/8, v/v/v) extracts of immunostained TLC bands were analyzed by nanoelectrospray low-energy CID mass spectrometry without further purification. The GSL species investigated were isomeric monosialogangliosides of the neolacto series from a ganglioside preparation of human granulocytes, the disialoganglioside GD3 from a human melanoma lipid extract, and ganglio series Gg3Cer of a neutral GSL preparation from murine lymphoreticular MDAY-D2 cells. For the specific detection of lipid-bound oligosaccharides, polyclonal chicken IgY, murine monoclonal IgG3, and IgM antibodies were used. The resulting mass spectra show that only analytical quantities of approximately 1 microg of a single GSL within a complex mixture are required for the structure determination of immunostained GSLs by MS and MS/MS. All species investigated were detected as singly charged deprotonated molecular ions, and neither buffer-derived salt adducts nor coextracted contaminants from the immunostaining procedure or the silica gel layer were observed. This effective HPTLC-MS-joined procedure offers a wide range of applications for any carbohydrate binding agents such as bacterial toxins, plant lectins, and others.

The role and potential of sialic acid in human nutrition

Sialic acids are a family of nine-carbon acidic monosaccharides that occur naturally at the end of sugar chains attached to the surfaces of cells and soluble proteins. In the human body, the highest concentration of sialic acid (as N-acetylneuraminic acid) occurs in the brain where it participates as an integral part of ganglioside structure in synaptogenesis and neural transmission. Human milk also contains a high concentration of sialic acid attached to the terminal end of free oligosaccharides, but its metabolic fate and biological role are currently unknown. An important question is whether the sialic acid in human milk is a conditional nutrient and confers developmental advantages on breast-fed infants compared to those fed infant formula. In this review, we critically discuss the current state of knowledge of the biology and role of sialic acid in human milk and nervous tissue, and the link between sialic acid, breastfeeding and learning behaviour.

Preferential binding of the anticancer drug rViscumin (recombinant mistletoe lectin) to terminally alpha2-6-sialylated neolacto-series gangliosides

Production of biochemically defined recombinant mistletoe lectin was achieved by cloning and separate expression of the single catalytically active A-chain and the B-chain with carbohydrate binding properties in Escherichia coli, yielding an active heterodimeric protein named rViscumin (Eck et al. [1999] Eur. J. Biochem., 265, 788-797). Employing solid phase binding assays, rViscumin was shown to preferentially bind to terminally alpha2-6-sialylated neolacto-series gangliosides IV(6)Neu5Ac-nLc4Cer, VI(6)Neu5Ac-nLc6Cer, and VIII(6)Neu5Ac-nLc8Cer isolated from human granulocytes. Only marginal binding of rViscumin to galactose-terminated neutral GSLs was determined, whereas reinvestigation of ricin specificity demonstrated this lectin as a galactose-binding protein. Human promyelotic HL-60 cells exhibited an IC(50) value (half maximum cytotoxicity) of 1.16 pM and human bladder carcinoma 5637 cells of 12.1 pM rViscumin; CHO-K1 cells were resistant to rViscumin treatment up to a concentration of 5.26 nM tested. Quantification of the predominant receptor ganglioside IV(6)Neu5Ac-nLc4Cer by means of a specific anti-Neu5Acalpha2-6Galbeta1-4GlcNAc-R antibody revealed 3.68 x 10(6) and 1.54 x 10(6) receptor molecules per HL-60 and 5637 cell, respectively; CHO-K1 cells were negative, lacking alpha2-6-sialylated gangliosides. The data imply a direct correlation of rViscumin cytotoxicity and the expression of receptor ganglioside. Moreover, CHO-K1 cells were rendered susceptible toward rViscumin cytotoxicity after exogenous application of human granulocyte gangliosides. Thus, (1) rViscumin has to be considered as a sialic acid-specific rather than a galactose-specific type II ribosome-inactivating protein, and (2) neolacto-series gangliosides with Neu5Acalpha2-6Galbeta1-4GlcNAc-terminus are true functional and physiologically relevant rViscumin receptors.

Ganglioside expression in tissues of mice lacking beta2-microglobulin

This study presents a comparative analysis of gangliosides from lymphoid (spleen and thymus) and other (brain, liver, lungs and muscle) tissues of C57BL/6 mice lacking the gene for beta2-microglobulin (beta2M), a constitutive component of the MHC class I molecule. Ganglioside fractions in the tissues of mice homozygous (beta2M-/-) and heterozygous (beta2M-/+) for the gene deletion were determined by high performance thin-layer chromatography (HPTLC), followed by immunostaining with specific polyclonal antibodies. Ubiquitous gangliosides GM3(Neu5Ac) and GM3(Neu5Gc) were the dominant gangliosides in the lungs of the control beta2M-/+ mice, whereas the homozygous knockout mice had substantially decreased expression of these structures. The lungs of the beta2M-/- mice also had reduced expression of T-lymphocyte-specific GM1b-type gangliosides (GM1b and GalNAc-GM1b). beta2M-deficient mice also had more GM1a and GD1a gangliosides in the liver, and several neolacto-series gangliosides were increased in the brain and lungs. This study provides in vivo evidence that the beta2M molecule can influence the acquisition of a distinct ganglioside assembly in different mouse organs, implicating its non-immunological functions.

Ganglioside patterns in human spinal cord

OBJECTIVE

To examine the distribution of gangliosides in human cervical and lumbar spinal cord.

SETTING

Magdeburg, Germany.

METHODS

The ganglioside distribution of human cervical and lumbar spinal cord enlargements from 10 neurological normal patients was analyzed. Gangliosides were isolated from different areas corresponding to the columna anterior, columna lateralis and columna posterior.

RESULTS

Ganglioside GfD1b/GD1b and GD3 were the most abundant gangliosides in all examined tissues. The total concentration of sialic acid bound gangliosides GM2 and GM3 was less than 5%. The GD3 fraction constantly consisted of a double band as assessed by TLC after lipid extraction. There were significant differences in the ganglioside distribution when comparing tissue from the columna anterior, columna lateralis and columna posterior of the lumbar enlargement of the spinal cord.

CONCLUSION

Differences in the ganglioside composition in human spinal cord regions may reflect the different function of those molecules in the two regions investigated.

Gangliosides from human granulocytes: a nano-ESI QTOF mass spectrometry fucosylation study of low abundance species in complex mixtures

Nano-ESI QTOF MS was used for sensitive mapping and sequencing of single molecular species in complex ganglioside mixtures obtained from human granulocytes, where the fucosylated carbohydrate chains of granulocyte gangliosides carry sLex and VIM-2 epitopes postulated to interact with E-selectin of the blood vessel wall in the early phase of the inflammation process. Functionally relevant components are expressed only at a low level, but using the negative ion detection it is possible to trace and identify such species, which were not detectable even by TLC. Advantage of the low-energy CID fragmentation for low abundance components of the complex ganglioside mixtures in the negative ion mode is to produce clear-cut series of fragment ions for sequencing. Fucosylation analysis carried out for each molecular species by MS/MS permits the clear distinction between sLex and VIM-2 epitope. VIM-2 epitope was expressed in all species with a longer sugar core, while in the short oligosaccharide chain with a sLex only, using biological material at a mid-femtomol level detection.

Metabolic studies of glycosphingolipid accumulation in mucopolysaccharidosis IIID

Severe neurological deficits and mental retardation are frequently associated with disrupted ganglioside metabolism in a variety of gangliosidoses and lysosomal storage disorders. Accumulation of glycosphingolipids (GSLs) in the central nervous system (CNS) of humans and animals affected with several types of mucopolysaccharidoses (MPS) also correlates with the severity of neurological dysfunction. Mucopolysaccharidosis type IIID (MPS IIID) is characterized by deficiency in lysosomal N-acetylglucosamine 6-sulfatase activity and the accumulation and excretion of heparan sulfates and N-acetylglucosamine 6-sulfate. We investigated the metabolism of GSLs in the prenatal, neonatal, and adult MPS IIID caprine brains and an MPS experimental cell culture model. The amounts of total glycolipids in prenatal, neonatal, and adult MPS IIID caprine brains were about 2-fold higher than those in control samples. GM3, GD3, and lactosyl ceramide were the principal GSLs which abnormally accumulated in caprine MPS IIID brains. These changes may be, in part, due to the reduction of sialidase and UDP-N-acetylgalactosamine:GM3 N-acetylgalactosaminyltransferase (GalNAc-T) activities in MPS IIID caprine brain. To further examine the possible mechanism of GSL accumulation in MPS IIID brains, we employed a cell culture model using suramin-treated neuronal cultures of differentiated P19 cells. HPTLC analysis showed elevated GSLs in suramin-treated cells. Metabolic pulse-chase labeling study revealed that the GSL accumulation in suramin-treated cells may be attributed to both disturbed biosynthesis and significantly slower degradation of GSLs. In addition, the consistency of observations in the cell culture and caprine models supports the cell culture system as a means of evaluating GSL metabolic perturbations.

Anencephaly: structural characterization of gangliosides in defined brain regions

Gangliosides from histopathologically-defined human cerebrum-resembling remnant and cerebellum from 37 and 30 gestational week-old anencephaluses were identified using mass spectrometry and high performance thin layer chromatography combined with immunochemical analysis in comparison to respective normal newborn/fetal and adult brain regions. A novel strategy of nano-electrospray ionization quadrupole time-of-flight tandem MS has been developed for identification of ganglioside components in complex mixtures. By morphoanatomical and histological investigation the anencephalic cerebral remnant was found to be aberrant, while the anencephalic cerebellum was defined as normal. Total ganglioside concentrations in the anencephalic cerebral remnant and the cerebellum were 34% and 13% lower in relation to the age-matched controls. In the cerebral remnant, GD3, GM2 and GT1b were elevated, while GD1a was decreased in the anencephalic cerebral remnant, but enriched in anencephalic cerebellum. GQ1b was reduced in both anencephalic regions. Gg4Cer, GM1b and GD1alpha, members of the alpha-series biosynthetic pathway, and neolacto-series gangliosides were found to be present in anencephalic, as well as in normal, fetal and adult brain tissues, indicating the occurrence of these biosynthetic pathways in human brain. In both cerebral and cerebellar anencephalic tissues, GM1b, GD1alpha, nLM1 and nLD1 were expressed at a higher rate in relation to normal tissue. It can be demonstrated that the anencephalic cerebral remnant, as a primitive brain structure, represents a naturally-occurring model to study the ganglioside involvement in induction of aberrant brain development.

Glycosphingolipid composition of a new immortalized human cerebromicrovascular endothelial cell line

Previous studies have demonstrated the involvement of glycosphingolipid (GSL) antigens in the pathogenesis of immune-mediated neurological disorders such as peripheral neuropathies and multiple sclerosis. To study the role of the blood-brain barrier (BBB) in these disorders, we used a new human cerebromicrovascular endothelial cell (HCEC) line that has been immortalized through transfection with the plasmid pSV3-neo encoding for the SV40 large T-antigen and the neomycin gene. The immortalized HCEC (SV-HCEC) exhibited accelerated proliferation rates but maintained phenotypic properties of early-passage control cells. Therefore, this human cell line may serve as a useful in vitro model for studying the properties of the human BBB. We first investigated the GSL composition of cultured SV-HCECs. The major gangliosides were GM3 (62% of total gangliosides), GM2 (18%), GM1 (3%), and GD1a (15%). The major neutral GSLs were glucosylceramide (15% of the total neutral glycolipids), lactosylceramide (36%), globotriaosylceramide (3%), and globoside (43%). Trace amounts of paragloboside, lactosaminyl paragloboside, and sulfoglucuronyl paragloboside could also be detected by TLC-immunostaining. These results provide the basis for further investigations of the expression of these cell surface antigens in cultured SV-HCECs on activation with inflammatory cytokines such as interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma, which have been implicated as playing an important role in the pathogenesis of many nervous system disorders.

An alkali-soluble factor present in normal brain tissue inhibits antigen-specific lymphocyte proliferation

The brain has long been recognized as an immune privileged site and probably contains multiple immune regulatory factors. We have investigated the immune regulatory properties of brain tissue on cultured lymphocytes. Homogenized brain tissue inhibits proliferation to antigen, but stimulates proliferation in response to most mitogens. The inhibitory activity is destroyed by treatment with proteases or neuraminadase. The activity is in the insoluble fraction of the homogenate, but becomes soluble in 0.04 M NaOH. After gel filtration chromatography of the alkali soluble material, the suppressive activity is in the high molecular weight fraction which contains protein and carbohydrate. The brain homogenate blocks the effects of IL-2. The activity is not affected by neutralizing antibodies against regulatory cytokines, does not depend on Fas or FasL, and is not due to the presence of gangliosides. These data suggest that a brain glycoprotein or proteoglycan which is either membrane-bound or part of the extracellular matrix has immune regulatory effects in culture. The relevance of these findings to immune regulation in the intact animal deserves further investigation.

Ganglioside expression in tissues of mice lacking the tumor necrosis factor receptor 1

This study presents a comparative analysis of gangliosides from lymphoid (spleen and thymus) and other tissues (brain, liver, lung, muscle) of C57BL/6 mice homozygous (-/-) and heterozygous (+/-) for the tumor necrosis factor receptor 1 (TNFRp55). Quantitative and qualitative differences in the expression of the lipid-bound N-acetylneuraminic (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) and of various ganglioside biosynthesis pathways were detected between the tissues of the TNFRp55 -/- and the control TNFRp55 +/- mice. Sialic acid profiles showed a strong decrease in the absolute amount of sialic acids (Neu5Ac + Neu5Gc) in the lungs and thymus of homozygous (1.41 and 0.3 ng/mg wet weight, respectively) compared with control heterozygous animals (7.18 and 2.05 ng/mg wet weight, respectively). Considerable differences of Neu5Ac/Neu5Gc ratios in the lungs, muscle, spleen, and thymus were also detected. The gangliosides GM3(Neu5Ac) and GM3(Neu5Gc) were the dominant gangliosides in the lungs of the control animals, whereas the knockout mice almost completely lacked these structures in this organ. Reduced expression of GM1b-type gangliosides (GM1b and GalNAc-GM1b) was also found in the lungs, spleen, and thymus of the TNFRp55 knockout mice. On the other hand, neolacto-series gangliosides were more abundant in the lungs, brain, and muscle of the knockout mice, whereas their expression in the liver, spleen, and thymus was similar in both groups of animals. This study provides in vivo evidence that TNF signaling via the TNFRp55 is involved in the acquisition of a distinct ganglioside assembly in different mouse organs. TNFRp55 signaling seems to be especially important for the activation of the GM1b-type ganglioside biosynthetic pathway that is a unique characteristic of the mouse lymphoid tissues.

Forssman penta- and tetraglycosylceramide are xenoantigens of ostrich kidney and liver

The heterophile antigens Galalpha1-->3Gal and N-glycolylneuraminic acid are the major obstacle to grafting mammal organs, especially from pig, to man. Lack of expression of these common xenoantigens by birds has raised interest in ostrich as a potential organ donor for xenotransplantation. Glycosphingolipids of ostrich liver and kidney were investigated for their carbohydrate determinants. Both organs were found similar in their glycolipid composition with three major species, mono-, di-, and pentaglycosylceramide. The pentaglycosylceramide was characterized as the Forssman antigen. In both organs, the ceramide portion was highly hydroxylated with prevalence of alpha-hydroxylated fatty acids, C18 phytosphingosine in kidney and C18 sphingosine in liver Forssman glycolipid. These data indicate that hydroxylation of kidney glycosphingolipids, which is found in mammals, has been maintained since the divergence of birds from other vertebrates. Characterization of a minor glycolipid as a Forssman tetraglycosylceramide built on the galabiosylceramide core indicates that the Forssman tetraglycosylceramide also exists in vivo. Its precursors, galactosyl- and galabiosylceramide, were characterized in kidney and liver. The Forssman antigen is the third heterophile antigen against which man raises natural antibodies. Its localization in the vascular endothelium and connective tissue makes ostrich an unpromising organ or cell donor for xenotransplantation to man.

Gangliosides and neutral glycolipids in ependymal, neuronal and primitive neuroectodermal tumors

Neutral glycolipid and ganglioside compositions were determined on 11 ependymal tumors, 12 medulloblastomas, 6 other neuronal tumors of the brain, 4 peripheral neuroblastomas, 1 cerebral primitive neuroectodermal tumor (PNET), and 1 PNET of the thoracic wall. Within the group of tumors that can demonstrate neuronal phenotypes, there was an association between the degree of neuronal differentiation usually demonstrated by these tumors and the proportions of both GD1a and 1b-pathway gangliosides. The amount of globoside also correlated with the amount of 1b pathway gangliosides. Patients with medulloblastomas whose 1b gangliosides made up over 15% of the total gangliosides survived longer that those with lower proportions of 1b gangliosides. The only gangliosides in the choroid plexus papilloma were GM3 and GD1a, but other ependymal tumors had significant amounts of GD1b and its metabolic precursors. Ependymoma and anaplastic ependymoma had similar neutral glycolipid compositions, which were different from subependymoma, which lacked ceramide monohexoside and ceramide dihexoside. These differences in glycolipid compositions suggest that there may be fundamental biological differences between these types of ependymal tumors.

Large scale purification of gangliosides GM3(Neu5Ac) and GM3(Neu5Gc) by trimethylaminoethyl-Fractogel high-performance liquid chromatography

A preparative anion-exchange high-performance liquid chromatographic method for the separation of the closely allied monosialogangliosides GM3(Neu5Ac) and GM3(Neu5Gc) has been developed. Hybridoma cells, readily available material derived from industrial monoclonal antibody production, were used as ganglioside source and led to fractions with pure GM3(Neu5Ac) and GM3(Neu5Gc) in high milligram quantities. The crude ganglioside extract was loaded onto columns filled with the strong anion-exchanger trimethylaminoethyl (TMAE)-Fractogel. Gangliosides were eluted from the stationary phase with a gradient system of ammonium acetate in methanol. The scaled-up approach ranged over more than one order of magnitude from 20 to 500 mg batches of GM3 gangliosides. Thus, the high-resolution power of the strong anion-exchanger TMAE-Fractogel allowed the preparative isolation by one-step column chromatography of two GM3 specimens which only differ in one hydroxyl group at position 5 of the neuraminic acid (N-acetyl-versus N-glycolylneuraminic acid).

Antibodies to GT1a ganglioside in patients with Guillain-Barré syndrome

Serum antibodies from 8 (13%) of 62 patients with the acute Guillain-Barré syndrome (GBS) and 1 of 3 patients with the Miller Fisher syndrome (MFS) recognized a minor ganglioside in bovine and human brain trisialoganglioside fractions. The ganglioside antigen migrated between GD1a and GD1b on thin-layer chromatograms. The structure of this ganglioside was established to be GT1a by thin-layer chromatography blotting and mass spectrometry. GT1a a ganglioside was also detected in human and bovine peripheral nerves by thin-layer chromatogram immunostaining. Serum from the GBS patients had IgM, IgG, or IgA antibodies against GT1a detectable by enzyme-linked immunosorbent assay (ELISA). Serum from the MFS patient also had elevated levels of IG against GT1a. None of the sera from 43 patients with other neurological diseases or from 24 healthy controls reacted with GT1a. Sera from 6 of 8 GBS patients with anti-Gt1a antibodies also reacted with GQ1b. There was no difference in the incidence of anti-GT1a immunoglobulins in acute GBS patients with or without oculomotor abnormalities. Levels of anti-GT1a antibodies correlated temporally wit clinical symptoms in GBS patients. Although the incidence of dysphagia was slightly higher in GBS patients with anti-GT1a antibodies than in those without, the number of patients studied may have been too small to detect an association between anti-GT1a antibodies and an a specific clinical variant of GBS. Our data demonstrate that a proportion of GBS patients have antibodies against GT1a ganglioside and suggest that these antibodies may play a role in the pathogenesis of neuropathy in GBS.

Lex glycosphingolipids-mediated cell aggregation

Glycoconjugates bearing oligosaccharide Lex, Galbeta1-->4(Fucalpha1-->3)GlcNAcbeta1-->3R, are found on the surface of several cell types. Although recent studies have indicated that Lexon both glycosphingolipids (GSL) and polylactosaminoglycans can mediate under certain experimental conditions Lex-Lexinteractions, cell-cell interactions based exclusively on LexGSLs have not been demonstrated. In this study we show that preincubation of nonaggregating rat basophilic leukemia (RBL) cells with purified LexGSLs resulted in incorporation of the GSLs into plasma membrane, as determined by immunostaining, and formation of aggregates in the presence of Ca2+; no aggregates were formed after preincubation of the cells with globoside or sphingomyelin. Lex-mediated aggregation was inhibited by removal of Ca2+or by addition of lactofucopentaose III but not by lactose or lacto-N-fucopentaose II. In a mixture of Lex-positive and Lex-negative RBL cells most of the aggregates were composed exclusively of Lex-positive cells. The combined data suggest that interactions between LexGSL on opposite cell surfaces are strong enough to allow formation of stable cell-cell contacts.

Sialic acid concentration of brain gangliosides: variation among eight mammalian species

Sialic acid is a vital component of brain gangliosides which play an essential role in the transmission and storage of information in the brain. The concentration of bound sialic acid in gangliosides and free sialic acid in the brain cortex of eight different mammals [human, chimpanzee (Pan troglodytes), rat (Rattus norvegicus), mouse (Mus musculus), rabbit (Oryctolagus cuniculus), sheep (Ovis aries), cow (Bos indicus) and pig (Sus scrofa)] were compared. Total sialic acid concentration (890+/-103 microg/g wet weight tissue, mean+/-SE, n = 6) was 2-4 times higher in the human brain compared with the other species studied (0.001 < p < 0.05). There was no significant difference between human males and females. The rank order of adult brain sialic acid after humans (in microg/g) was rat (493+/-23, n = 12), mouse (445+/-29, n = 16), rabbit (380+/-18, n = 6), sheep (323+/-43, n = 6), cow (304+/-14, n = 6) and pig (252+/-14, n = 6). Apart from the cow vs the sheep, the differences between species were statistically significant (p < 0.05). In the mouse, cow and sheep, total sialic acid concentration increased during maturation by 18-32% (p < 0.05). In a 2-year-old chimpanzee, the sialic acid concentration in the left lobe of the brain cortex was 25% higher than that of right lobe at 6 weeks of age (p < 0.05). Free sialic acid was higher in the human brain cortex (41+/-3 microg/g) than that of the rat and mouse (32+/-3 and 25+/-5 microg/g respectively) and absent from other species. Variation in brain sialic acid concentration among different animals has implications for the evolution of the brain and may affect learning ability in animals.

Acute motor axonal neuropathy with high titer IgG and IgA anti-GD1a antibodies following Campylobacter enteritis

We describe the first two European cases of acute axonal motor neuropathy with both IgG and IgA anti-GD1a antibodies following Campylobacter enteritis. Both patients acutely developed severe weakness without sensory involvement, had antibodies to Campylobacter jejuni and polyclonal IgG and IgA titers > or = 12,800 to GD1a at onset, which decreased during follow-up. Serial electrophysiologic studies showed: 1, normal or only slightly slowed motor conductions; 2, evidence of a progressive loss of excitability and conduction failure in nerve fibers undergoing axonal degeneration in intermediate nerve segments and evidence of distal axonal involvement in one nerve; 3, normal sensory conductions, sensory potential amplitudes and somatosensory evoked potentials. Although we cannot exclude that axonal degeneration followed demyelination, we think that anti-GD1a antibodies account for the axonal involvement because GD1a is present in the axolemma and exposed at the node of Ranvier and in nerve terminals. The exclusive motor involvement could be explained by the fact that GD1a has a different internal structure in motor and sensory fibers.

Ganglioside composition of the human cranial nerves, with special reference to pathophysiology of Miller Fisher syndrome

Total ganglioside fractions from the human cranial nerves purified on a Phenyl Sepharose column, were given mild alkaline treatment, after which their composition and amounts of lipid-bound sialic acid were determined by HPTLC-densitometry with resorcinol as the coloring reagent. The total amounts of lipid-bound sialic acid were 156.5 ng/mg of wet tissue in the Ist cranial nerve (olfactory tract) and 131.9 ng/mg in the IInd nerve, greater than the amounts in the other nerves (99.1-120.0 ng/mg). The Ist, IInd, and VIIIth nerves had GM4, but not LM1. It may reflect their histological feature of the central nervous system. The IIIrd, IVth, and VIth nerves, as well as the IInd, had significantly higher percentages of GQ1b (11.6-13.2%) than the other nerves (5.2-8.4%). The high proportion of GQ1b specific to these three cranial nerves involved in the ocular movement lends support to the role of serum anti-GQ1b antibody in the pathogenetic mechanisms of ophthalmoplegia in Miller Fisher syndrome and Guillain-Barré syndrome.

Simultaneous expression by porcine aorta endothelial cells of glycosphingolipids bearing the major epitope for human xenoreactive antibodies (Gal alpha 1-3Gal), blood group H determinant and N-glycolylneuraminic acid

Glycosphingolipids were isolated from primary cultures of porcine endothelial cells labelled with 14C-galactose or 14C-glucosamine. They were characterized by their mobility on thin layer chromatogram, their sensitivity to exoglycosidases, and their labelling with antibodies. In addition to the major glycosphingolipids, globotetra- and globotriaosylceramide, minor ones were identified as penta- and heptaglycosylceramide of the neolactoseries terminated by either Gal alpha 1-3Gal- (xenoreactive epitope) or Fuc alpha 1-2Gal- (H determinant). Two gangliosides were found, GM3 and GD3, and N-glycolylneuraminic acid was their major sialic acid. Therefore, porcine endothelial cells differ from human endothelial cells by expression of glycosphingolipids that are absent in man: two Gal alpha 1-3Gal-terminated glycolipids recognized by human natural antibodies, and two N-glycolylneuraminic acid-terminated gangliosides which are potent immunogens.

Influenza A and Sendai viruses preferentially bind to fucosylated gangliosides with linear poly-N-acetyllactosaminyl chains from human granulocytes

Influenza A and Sendai viruses are known to bind to various extent to neolacto-series gangliosides IV3Neu5Ac-nLcOse4Cer, IV6Neu5Ac-nLcOse4Cer, and VI3Neu5Ac-nLcOse6Cer, which are the dominant gangliosides of human granulocytes. Recently, minor gangliosides of granulocytes were characterized and found to express sialyl Lewis(x) and VIM-2 epitopes. These long chain linear monosialogangliosides with nLcOse8, and nLcOse10, cores, carrying one to three fucoses, are shown in this study to bind with strong avidity to influenza A/PR/8/34 (H1N1), A/X-31 (H3N2), and Sendai virus (Z-strain) using the overlay technique. These and recent data from other groups imply that selectins and virus hemagglutinins are capable of competing with lipid bound sialyl Lewis(x) and VIM-2 epitopes on myeloid cells during inflammatory reactions.

Replacement of chloroform throughout glycosphingolipid isolation

Chloroform, the predominant constituent of solvents used for lipid extraction and chromatography, is believed to give rise to birth defects and serious damage to health, and may also be carcinogenic. Therefore, simple and successful methods have been developed to replace chloroform throughout the isolation of glycosphingolipids (GSLs) by less harmful solvents. Gangliosides of sheep brain (ganglio-series gangliosides GM1, GDla, GD1b and GT1b) and of lymphocyte-derived mouse hybridoma cells (namely GM3) were extracted with six different solvent mixtures. Chloroform:methanol:water (40:80:30, v/v/v) was employed as reference (solvent I). Combinations without chloroform were: n-propanol:water (40:10, v/v) (II), methylisobutylketone:methanol:water (40:80:30, v/v/v) (III), ethylacetate:methanol:water (40:72:28, v/v/v) (IV), methylacetate:methanol:water (40:72:28, v/v/v) (V) and petroleum ether:isopropanol:water (40:112:38, v/v/v) (VI). After extraction and dialysis, the weight of lipid extract as well as the content of sialic acid, gangliosides, sulphatides and phospholipids were determined. Quantitation of GSL yields in crude extracts obtained by the alternative solvent mixtures II to VI showed recoveries of brain gangliosides from nearly 67% up to 104% compared with the reference solvent I. Extraction of hybridoma cells by means of the alternative combinations without chloroform revealed at least the same and mostly better ganglioside yields in the range from 98% to 116% with regard to the reference solvent I. n-Propanol:water (II) and methylisobutylketone:methanol:water (III) were the recommended extractants for both tissues. Therefore, the methods described offer simple, less hazardous and successful strategies for GSL extraction in excellent yield without the need for using chloroform.

Postnatal development of glycosidases and gangliosides in the rat central nervous system

The developmental profiles of sialidase, beta-galactosidase, beta-hexosaminidase and beta-glucosidase were compared to those of the gangliosides in rat brain and spinal cord. The glycosidase activities (enzyme units/g wet tissue), except beta-galactosidases, were found to be higher in brain than spinal cord, in adult rats. Among the hydrolases, beta-hexosaminidase showed a higher level of activity in both brain and spinal cord. In brain, the hydrolases, except beta-glucosidase, followed a similar developmental pattern, showing an increase from birth to 21 days, and then decreased to adult values by day 90. In the spinal cord, sialidase, beta-galactosidase, pH 3.1, and beta-hexosaminidase activities increased from birth to 21 days, reaching peak values. These activities then declined to adult values by 90 days of age. However, beta-galactosidase, pH 4.5, and beta-glucosidase activities showed a peak at day 14. Brain total ganglioside concentration (microgram N-acetylneuraminic acid/g tissue) increased slowly between birth and 7 days of age, followed by a rapid phase of increase to attain a peak value by day 21. The concentration of total gangliosides in the spinal cord is less when compared to the brain. The proportions of individual gangliosides in the central nervous system also vaired during development. The rapid phase of increase in enzyme activities between 0-7 and 14-21 days and a decrease thereafter is consistent with the turnover rate of gangliosides, which in rat brain is reported to be highest between 10 and 20 days.

High-resolution thin-layer chromatography of gangliosides

In this review an updated overview of current improvements on thin-layer chromatography (TLC) of gangliosides over the past decade is provided. Basic general techniques and special advice is given for successful separation of glycosphingolipids. New approaches concerning continuous and multiple development, and several preparative TLC methods are also included. Emphasis is placed on TLC immunostaining and related techniques, i.e. practical applications of carbohydrate-specific antibodies, toxins and bacteria, viruses, lectins and eukaryotic cells. Thus, this review on ganglioside TLC summarizes its power as an analytical tool for a wide range of purposes.

Structure and genetic polymorphism of blood group A-active glycosphingolipids of the rat large intestine

Study of blood group A- and B-active glycosphingolipid content of the epithelium of the large intestine of 16 strains of inbred rats led to the discovery of two related strains, SHR and WKY, devoid of A-active glycolipids, whereas all strains expressed B-active glycolipids. This finding evidenced a new A/non-A genetic polymorphism in the rat. Blood group A-active glycolipids were isolated from the large intestine of F344 rats and purified by affinity chromatography on immobilized Helix pomatia lectin. Three glycolipid fractions were separated by preparative thin-layer chromatography and characterized by electron-impact mass spectrometry of their permethylated and permethylated-LiAlH4-reduced derivatives. They were identified as a tetraglycosylceramide (A-4), a hexaglycosylceramide (A-6), and a difucosylated heptaglycosylceramide (A-7) with small amounts of monofucosylated octaglycosylceramide (A-8). Methylation analysis and fragmentation indicated that A6 and A-8 had a lacto- and A-7 a neolactotetraosylceramide core, respectively, identical to the core structures of B-6 and B-7 previously characterized in the large intestine of WF rats (Angström et al. (1987) Biochim. Biophys. Acta 926, 79-86). Upon methylation analysis, B-6 and B-7 purified from SHR (A-deficient) and F344 (A-expressing) were found identical to those of WF rats. This result indicated that precursor substrates for the synthesis of A-active glycolipids were available in SHR rats and thus the genetic deficiency of A-active glycolipid expression probably originated in a defect of the termination of the blood group A determinant by the alpha-3-N-acetylgalactosaminyltransferase.