Gangliosides and sulphatide in human cerebrospinal fluid: quantitation with immunoaffinity techniques

Ganglioside analysis in body fluids by liquid-phase separation techniques hyphenated to mass spectrometry

The expression of gangliosides in central nervous system is a few times higher than in the extraneural tissue, a characteristic highlighting their major role at this level. Although in very low amounts, gangliosides are ubiquitously distributed in body fluids too, where, depending on many factors, including pathological states, their composition fluctuates, thus having diagnostic value. Ganglioside investigation in biological fluids, which, except for cerebrospinal fluid (CSF), may be sampled noninvasively, was for years impeded by the limited sensitivity of the analytical instrumentation available in glycomics. However, because the last decade has witnessed significant developments in biological mass spectrometry (MS) and the hyphenated separation techniques, marked by a major increase in sensitivity, reproducibility, and data reliability, ganglioside research started to be focused on biofluid analysis by separation techniques coupled to MS. In this context, our review presents the achievements in this emerging field of gangliosidomics, with a particular emphasis on modern liquid chromatography (LC), thin-layer chromatography, hydrophilic interaction LC, and ion mobility separation coupled to high-performance MS, as well as the results generated by these systems and allied experimental procedures in profiling and structural analysis of gangliosides in healthy or diseased body fluids, such as CSF, plasma/serum, and milk.

GM1 Ganglioside Is A Key Factor in Maintaining the Mammalian Neuronal Functions Avoiding Neurodegeneration

Many species of ganglioside GM1, differing for the sialic acid and ceramide content, have been characterized and their physico-chemical properties have been studied in detail since 1963. Scientists were immediately attracted to the GM1 molecule and have carried on an ever-increasing number of studies to understand its binding properties and its neurotrophic and neuroprotective role. GM1 displays a well balanced amphiphilic behavior that allows to establish strong both hydrophobic and hydrophilic interactions. The peculiar structure of GM1 reduces the fluidity of the plasma membrane which implies a retention and enrichment of the ganglioside in specific membrane domains called lipid rafts. The dynamism of the GM1 oligosaccharide head allows it to assume different conformations and, in this way, to interact through hydrogen or ionic bonds with a wide range of membrane receptors as well as with extracellular ligands. After more than 60 years of studies, it is a milestone that GM1 is one of the main actors in determining the neuronal functions that allows humans to have an intellectual life. The progressive reduction of its biosynthesis along the lifespan is being considered as one of the causes underlying neuronal loss in aged people and severe neuronal decline in neurodegenerative diseases. In this review, we report on the main knowledge on ganglioside GM1, with an emphasis on the recent discoveries about its bioactive component.

Binding affinity of amyloid oligomers to cellular membranes is a generic indicator of cellular dysfunction in protein misfolding diseases

The conversion of peptides or proteins from their soluble native states into intractable amyloid deposits is associated with a wide range of human disorders. Misfolded protein oligomers formed during the process of aggregation have been identified as the primary pathogenic agents in many such conditions. Here, we show the existence of a quantitative relationship between the degree of binding to neuronal cells of different types of oligomers formed from a model protein, HypF-N, and the GM1 content of the plasma membranes. In addition, remarkably similar behavior is observed for oligomers of the Aβ₄₂ peptide associated with Alzheimer’s disease. Further analysis has revealed the existence of a linear correlation between the level of the influx of Ca²⁺ across neuronal membranes that triggers cellular damage, and the fraction of oligomeric species bound to the membrane. Our findings indicate that the susceptibility of neuronal cells to different types of misfolded oligomeric assemblies is directly related to the extent of binding of such oligomers to the cellular membrane.

Lipids and glycosphingolipids in caveolae and surrounding plasma membrane of primary rat adipocytes

We have made a comprehensive and quantitative analysis of the lipid composition of caveolae from primary rat fat cells and compared the composition of plasma membrane inside and outside caveolae. We isolated caveolae from purified plasma membranes using ultrasonication in carbonate buffer to disrupt the membrane, or extraction with nonionic detergent, followed by density gradient ultracentrifugation. The carbonate-isolated caveolae fraction was further immunopurified using caveolin antibodies. Carbonate-isolated caveolae were enriched in cholesterol and sphingomyelin, and the concentration was three- and twofold higher, respectively, in caveolae compared to the surrounding plasma membrane. The concentration of glycerophospholipids was similar suggesting that glycerophospholipids constitute a constant core throughout the plasma membrane. The composition of detergent-insoluble fractions of the plasma membrane was very variable between preparations, but strongly enriched in sphingomyelin and depleted of glycerophospholipids compared to carbonate-isolated caveolae; indicating that detergent extraction is not a suitable technique for caveolae preparation. An average adipocyte caveola contained about 22 x 10(3) molecules of cholesterol, 7.5 x 10(3) of sphingomyelin and 23 x 10(3) of glycerophospholipid. The glycosphingolipid GD3 was highly enriched in caveolae, whereas GM3, GM1 and GD1a were present inside as well as outside the caveolae membrane. GD1b, GT1b, GM2, GQ1b, sulfatide and lactosylceramide sulfate were not detected in caveolae.

Glycosphingolipids as potential diagnostic markers and/or antigens in neurological disorders

Glycosphingolipids are most abundant in the nervous system within which are developmental, regional, structural and cellular differences regarding their composition. The are shedded to the cerebrospinal fluid and thus potential markers for pathogenic alterations in the brain, such as developmental abnormalities, demyelination, gliosis, neuronal cell destruction. The glycosphingolipids have also been found to be antigens in autoimmune processes involving the nervous system, in particular in peripheral neuropathies like Guillain Barré syndrome, multifocal motor neuropathy etc. The immune response might have been triggered by infectious agents with an antigen epitope which mimic the glycosphingolipid or by a primary nerve tissue damage leading to release of glycosphingolipids. There is a series of support for a clinical significance of cerebrospinal fluid glycosphingolipid determinations and the presence of anti-glycosphingolipid antibodies but this has to be further explored. This paper is a mini review of the state of the art and discuss methodological aspects and improvements that might help to explore the relevance of glycosphingolipids in neurological disorders.

Glycosphingolipid expression in human skeletal and heart muscle assessed by immunostaining thin-layer chromatography

In this study the comparative TLC immunostaining investigation of neutral GSLs and gangliosides from human skeletal and heart muscle is described. A panel of specific polyclonal and monoclonal antibodies as well as the GM1-specific choleragenoid were used for the overlay assays, combined with preceding neuraminidase treatment of gangliosides on TLC plates. This approach proved homologies but also quantitative and qualitative differences in the expression of ganglio-, globo- and neolacto-series neutral GSLs and gangliosides in these two types of striated muscle tissue within the same species. The main neutral GSL in skeletal muscle was LacCer, followed by GbOse3Cer, GbOse4Cer, nLcOse4Cer and monohexosylceramide, whereas in heart muscle GbOse3Cer and GbOse4Cer were the predominant neutral GSLs beside small quantities of LacCer, nLcOse4Cer and monohexosylceramide. No ganglio-series neutral GSLs and no Forssman GSL were found in either muscle tissue. GM3(Neu5Ac) was the major ganglioside, comprising almost 70% in skeletal and about 50% in cardiac muscle total gangliosides. GM2 was found in skeletal muscle only, while GD3 and GM1b-type gangliosides (GM1b and GD1 alpha) were undetectable in both tissues. GM1a-core gangliosides (GM1, GD1a, GD1b and GT1b) showed somewhat quantitative differences in each muscle; lactosamine-containing IV3Neu5Ac-nLcOse4Cer was detected in both specimens. Neutral GSLs were identified in TLC runs corresponding to e.g. 0.1 g muscle wet weight (GbOse3Cer, GbOse4Cer), and gangliosides GM3 and GM2 were elucidated in runs which corresponded to 0.2 g muscle tissue. Only 0.02 g and 0.004 g wet weight aliquots were necessary for unequivocal identification of neolacto-type and GM1-core gangliosides, respectively. Muscle is known for the lowest GSL concentration from all vertebrate tissues studied so far. Using the overlay technique, reliable GSL composition could be revealed, even from small muscle probes on a sub-orcinol and sub-resorcinol detection level.

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.

Extraction and purification of gangliosides from plasma and fibroblasts before analysis by thin layer chromatography

A procedure to extract and purify gangliosides from small volumes of plasma (0.6 mL), cerebrospinal fluid (1 mL) and fibroblasts is described. Gangliosides were extracted with chloroform/methanol and purified by means of reversed phase chromatography and gel filtration before analysis by thin layer chromatography. The procedure proved to be useful in confirming deficiency of lysosomal enzyme activity affecting ganglioside breakdown. The new procedure also appeared to be useful to monitor ganglioside catabolism in cultured fibroblasts loaded with ganglioside.

Detection of glioma-associated gangliosides GM2, GD2, GD3, 3'-isoLM1 3',6'-isoLD1 in central nervous system tumors in vitro and in vivo using epitope-defined monoclonal antibodies

In this study, MAbs to the 'conventional' gangliosides expressed by human gliomas were generated and used to detect ganglioside species previously unisolated or defined in normal adult CNS tissue. Despite the marked phenotypic and genotypic heterogeneity shown by glioma cell lines (Bigner et al., 1981), the ganglioside phenotype of these cell lines is remarkably consistent qualitatively, if not quantitatively, in the ganglioside species expressed (Table V). The majority of cell lines and tumor samples express GM2, GD2 and GD3; this does not provide a diagnostic advantage (Vick et al., 1992). Nevertheless, as the relative amounts of these gangliosides in tumor as compared with normal adult CNS tissue is considerable, such reagents might be considered in compartmental immunotherapeutic approaches. Since GD2 and GD3 have been determined to mediate tumoricidal activity with human effector cells via specific antiganglioside epitope MAbs (Thurin et al., 1987; Kushner and Cheung, 1991; Barker et al., 1991; Reisfeld, 1993), cell-mediated approaches, as well as targeted immunoglobulin therapies, are also possible. The prospect of a more targeted approach with little or no effect on normal CNS tissue is now possible via the 'oncofetal' epitopes characteristic of 3'-isoLM1 and 3',6'-isoLD1. Several factors recommend the use of these moieties for compartmental immunotherapy; the inability to detect them within the adult CNS; the relatively high frequency of expression of 3'-isoLM1 and 3',6'-isoLD1, especially in human tumor samples (50-100%, depending upon the series and assay); and the existence of specific MAbs reactive with these epitopes. Current technology is being applied to these MAbs to transfer the specific recognition capacity of existing murine MAbs into various human framework structures of any desired immunoglobulin class, and thereby, biologic function. The variety of effector functions, the stability in affinity, labeling capacity, and the exquisite sensitivity of these MAbs for these glioma-distinctive epitopes is an exciting and promising approach for immunotherapy of human CNS tumors.

Normal developmental profiles of CSF gangliotetraose-series gangliosides from neonatal period to adolescence

The normal developmental profiles of cerebrospinal fluid (CSF) gangliosides were examined from the neonatal period to adolescence, using 1 ml of clinically available CSF, by the thin-layer chromatography/enzyme-immunostaining method. The level of total gangliotetraose-series gangliosides, including GM1, GD1a, GT1a, GD1b, GT1b, and GQ1b, increased 3.8-fold from the neonatal period to age 5 years, followed by a plateau, and then a mild decrease. The developmental profiles of individual gangliosides differed from each other. CSF gangliosides change with age, reflecting the maturational changes of the central nervous system gangliosides in situ. CSF ganglioside analysis and this developmental profile might be useful for examining ganglioside aberrations and basic neurochemical mechanisms underlying neurologic disorders, especially age-dependent diseases.

Competitive binding assay for quantitative determination of GM1 ganglioside in plasma and cerebrospinal fluid

A competitive binding assay for the quantitative determination of GM1 ganglioside is described. After extraction from biological fluids, GM1 was incubated with a known amount of cholera toxin B-subunit conjugated with horseradish peroxidase, and exposed to GM1 adsorbed onto polystyrene microwells. Since GM1 in solution blocks the binding of toxin B-subunit to GM1 adsorbed onto the solid phase, enzyme activity serves as a reciprocal measure of GM1 concentration in the sample. The assay was used to determine the basal level of GM1 in plasma and cerebrospinal fluid in different populations.

Immunosuppression by human gangliosides. II. Carbohydrate structure and inhibition of human NK activity

Gangliosides shed by tumors enhance tumor formation, possibly by suppressing host antitumor immune function, and gangliosides purified from animal tissues and cultured cells inhibit human cellular immune function in vitro. Determination of immunosuppressive activity of highly purified gangliosides, to uncover structure-activity relationships, is therefore important. Here we have studied a series of gangliosides obtained from human tissue and determined their effects on human natural killer (NK) activity. Total gangliosides from human brain tissue were moderately inhibitory; 100 nmol/ml reduced NK activity of human nonadherent PBMC by 43%. The influence of carbohydrate structure upon inhibitory activity was determined by study of eight highly (HPLC) purified individual gangliosides. Of these, we unexpectedly found that the two minor brain gangliosides with the simplest carbohydrate structures, GM2 and GM3, were very active inhibitors (75 and 47%, respectively, at 50 nmol/ml). In contrast, the structurally more complex major species, GM1, GD1a, GD1b, GT1b, and two other minor gangliosides, GD2 and GD3, were inactive. Reduced effector-target binding in a single-cell binding assay by GM2 but not GM3 suggests different mechanisms of inhibition by these two active gangliosides. Since GM2 and GM3 are present in high concentrations in, and are shed by, several common human tumors (e.g., neuroblastoma, melanoma, and glioma), their ability to inhibit NK cytotoxicity supports the hypothesis of a role of shed tumor gangliosides in the enhancement of tumor formation.

Gangliosides of human cerebrospinal fluid in various neurologic diseases

Simultaneous profile determination and quantification of human cerebrospinal fluid (CSF) gangliosides in various neurologic diseases (n = 71) was examined. Gangliosides were extracted with methanol/chloroform from clinically available amounts of CSF (4-5 ml), then separated and quantified by high-performance thin-layer chromatography (HPTLC) and direct densitometry. Based on chromatographic comparison with standards, the percentage of lipid-bound NeuAc positive fractions in 'normal' CSF samples were: GM1 (II3 NeuAc-GgOse4Cer) (3%); GD3 (II3 NeuAc2-Lac-Cer) (4%); GD1a (IV3 NeuAc, II3 NeuAc-GgOse4 Cer) (15%); X1 (3%); GD1b (II3(NeuAc)2-GgOse4 Cer) (16%); X2 (4%); GT1b (IV3 NeuAc, II3(NeuAc)2-GgOse4-Cer) (40%); and GQ1b (IV3(NeuAc)2, II3(NeuAc)2-GgOse4-Cer (15%). Similarity between CSF and CSF and human cerebellar cortex, particularly in proportion of "b" series gangliosides (GQ1b, GT1b, GD1b), could be observed. A higher proportion of GD1a ganglioside, with decreased GQ1b was found in infancy. The total ganglioside content (mean +/- 2 SD) varied between 645-894 micrograms/l. Significant alterations of the CSF ganglioside profile, with an increase in less polar gangliosides, GM3 and GD3, correlated with the blood-brain barrier dysfunction (CSF hemorrhages, compressive syndrome), or some malignant processes (metastatic brain melanoma). A statistically significant increase in the content of total CSF gangliosides was found in the following groups of patients as compared to controls: (1) ischemic cerebrovascular accident (CVI) with good outcome (P less than 0.02); (2) peripheral neuropathy and polyneuropathy (P less than 0.001) and (3) intravertebral discopathy (P less than 0.05). A significant decrease in the content of total CSF gangliosides was found in CVI group with lethal outcome (P less than 0.05).

Human brain lectin immunoreactive material in cerebrospinal fluids determined by enzyme immunoassay (EIA)

A sensitive enzyme immunoassay (EIA) micromethod is described which can measure levels of a 14 kDa human brain lectin (HBL) in the cerebrospinal fluid (CSF) of patients submitted to CSF examination. The assay is based on the use of a polyclonal antibody to HBL and the simultaneous application of biotinylated and unlabeled HBL. Biotin was then reacted with a streptavidin-peroxidase (Strep-HRP) conjugate and the bound enzyme quantified with the substrate orthophenylenediamine (OPD). The assay requires only 50 microliters of CSF and is very sensitive: as little as 6 ng/ml of HBL 14 can be detected. In a blind-test screening, the mean (+/- SEM) concentration of the HBL immunoreactive material (HIM) in CSF was determined to be 72.4 +/- 6.6 ng/ml. Our results indicate that EIA measurement of HIM levels in the CSF may find useful applications in elucidating the involvement of HBL in the physiopathology of human nervous system (NS).

Determination of gangliosides and sulfatide in human cerebrospinal fluid with a microimmunoaffinity technique

An immunostaining procedure has been developed for the assay of the gangliotetraose gangliosides and sulfatide in cerebrospinal fluid. Gangliosides of the gangliotetraose series were individually determined with cholera toxin B-subunit (CT-B) and an anti CT-B monoclonal antibody after chromatography and sialidase hydrolysis to GM1 on high performance thin-layer plates. Sulfatide was determined by thin-layer chromatography using an anti-sulfatide antibody. The method was applied to normal cerebrospinal fluid from 20 adults and 30 children. The concentration of the gangliotetraose series gangliosides in adults varied from 100-300 nmol/l with a mean value of 230 +/- 56 nmol/l. Corresponding values for sulfatide were 30-225 nmol/l and 140 +/- 46 nmol/l. The values for gangliosides and sulfatide in children increased during development. The major gangliosides in cerebrospinal fluid of adults were GT1b and GD1b and in children GD1a and GT1b.

Glycosphingolipids in the cerebrospinal fluid of patients with multiple sclerosis

Glycosphingolipids in cerebrospinal fluid (CSF) of individual patients with multiple sclerosis (MS) were analyzed using a glycolipid-overlay technique. The ganglioside composition of CSF of non-MS patients was characterized by an abundance of polysialo species, including GT1b and GQ1b. This pattern is completely different from that of human white or gray matter, in which mono- and disialogangliosides predominate. Increased levels of GM1, either associated with or without increases of other gangliosides, such as GD1a, were observed in 16% of the patients with MS (6 of 37 cases: 1 of 15 progressive progressive stage, 4 of 16 progressive stationary stage, and 1 of 6 relapsing stage). The concentration of GD3 was increased in 23% (3 of 13 cases), whereas 1 of 13 cases (8%) showed a dramatic increase of sulfoglucuronyl paragloboside (SGPG) associated with a high level of GD3. These changes may reflect the cellular changes associated with the known pathological lesions in MS, which are characterized by demyelination, gliosis, and/or remyelination with oligodendrocytic proliferation.

Circulating glycoconjugates in CSF of meningioma patients

This study investigated whether tumor-associated gangliosides or glycoproteins may be markers for meningiomas in CSF. The concentrations of a number of gangliosides and sulphatide were determined with specific monoclonal antibodies and cholera toxin B-subunit in a thin-layer chromatography overlay technique. As compared to a reference group of 10 individuals (mean age 50 +/- 14 years), the CSF samples from 7 meningioma patients (mean age 55 +/- 12 years) were found to contain significantly increased concentrations of ganglioside GD3 [II3(NeuAc)2-LacCer], one of the major gangliosides in meningioma tissue specimens. Sulphatide was significantly increased in 6 of 7 patients. Tumor-associated glycoproteins detected by the lectin Ricinus communis 1 in meningioma tissue specimens, but not in normal human brain tissue, were also found in the CSF of the meningioma patients. An early diagnosis of meningiomas might be achieved by the combined assay in CSF of ganglioside GD3 and glycoproteins with Ricinus communis lectin.