Multiple phenotypic changes in mice after knockout of the B3gnt5 gene, encoding Lc3 synthase--a key enzyme in lacto-neolacto ganglioside synthesis

BACKGROUND

Ganglioside biosynthesis occurs through a multi-enzymatic pathway which at the lactosylceramide step is branched into several biosynthetic series. Lc3 synthase utilizes a variety of galactose-terminated glycolipids as acceptors by establishing a glycosidic bond in the beta-1,3-linkage to GlcNaAc to extend the lacto- and neolacto-series gangliosides. In order to examine the lacto-series ganglioside functions in mice, we used gene knockout technology to generate Lc3 synthase gene B3gnt5-deficient mice by two different strategies and compared the phenotypes of the two null mouse groups with each other and with their wild-type counterparts.

RESULTS

B3gnt5 gene knockout mutant mice appeared normal in the embryonic stage and, if they survived delivery, remained normal during early life. However, about 9% developed early-stage growth retardation, 11% died postnatally in less than 2 months, and adults tended to die in 5-15 months, demonstrating splenomegaly and notably enlarged lymph nodes. Without lacto-neolacto series gangliosides, both homozygous and heterozygous mice gradually displayed fur loss or obesity, and breeding mice demonstrated reproductive defects. Furthermore, B3gnt5 gene knockout disrupted the functional integrity of B cells, as manifested by a decrease in B-cell numbers in the spleen, germinal center disappearance, and less efficiency to proliferate in hybridoma fusion.

CONCLUSIONS

These novel results demonstrate unequivocally that lacto-neolacto series gangliosides are essential to multiple physiological functions, especially the control of reproductive output, and spleen B-cell abnormality. We also report the generation of anti-IgG response against the lacto-series gangliosides 3'-isoLM1 and 3',6'-isoLD1.

GMab-1, a high-affinity anti-3'-isoLM1/3',6'-isoLD1 IgG monoclonal antibody, raised in lacto-series ganglioside-defective knockout mice

The lacto-series gangliosides 3'-isoLM1 and 3',6'-isoLD1 have been identified as tumor-associated antigens whose formation is initiated by the Lc3-synthase. Until now, high-affinity IgG monoclonal antibodies (mAbs) against 3'-isoLM1 and 3',6'-isoLD1, which are highly expressed in gliomas, have not been developed, although mAbs against lacto-series gangliosides are powerful tools for functional studies. We previously produced the Lc3-synthase gene beta3Gn-T5 knockout mice. In this study, we immunized beta3Gn-T5 knockout mice with 3'-isoLM1/3',6'-isoLD1 and produced the anti-3'-isoLM1/3',6'-isoLD1 mAb GMab-1, of the IgG(3) subclass, which should be useful for functional analysis of lacto-series gangliosides and for antibody-based therapy of gliomas.

S100 in mild traumatic brain injury

PRIMARY OBJECTIVES

To examine the diagnostic value of S100 in mild traumatic brain injury (MTBI).

RESEARCH DESIGN

Prospective cohort study.

METHODS AND PROCEDURES

S100B, S100A1B and S100BB concentrations were examined in sera from patients with MTBI with an arrival Glasgow Coma Scale score of 15 or 14, patients with orthopaedic injuries and non-injured subjects.

MAIN OUTCOME AND RESULTS

Mean values and proportions of subjects above cut-off limits for S100B and S100A1B were significantly higher in each trauma group than in non-injured controls, but only for S100A1B when patients with MTBI were compared with controls with orthopaedic injuries. Using a 97.5 percentile cut-off limit, the sensitivity of S100A1B for MTBI vs orthopaedic injury was 61% (95% confidence interval (CI) 49-73%), specificity 77% (95% CI 62-93%). The area under the ROC curve did not approach 0.9 for any cut off limit.

CONCLUSIONS

Diagnostic validity of S100 in acute MTBI was not demonstrated. S100A1B has merits for long-term prognostic studies.

Cerebrospinal fluid markers before and after shunting in patients with secondary and idiopathic normal pressure hydrocephalus

Background

The aim of this study was to explore biochemical changes in the cerebrospinal fluid (CSF) induced by shunt surgery and the relationship between these changes and clinical improvement.

Methods

We measured clinical symptoms and analysed lumbar CSF for protein content, neurodegeneration and neurotransmission markers in patients with secondary (SNPH, n = 17) and idiopathic NPH (INPH, n = 18) before and 3 months after shunt surgery. Patients were divided into groups according to whether or not there was improvement in clinical symptoms after surgery.

Results

Preoperatively, the only pathological findings were elevated neurofilament protein (NFL), significantly more so in the SNPH patients than in the INPH patients, and elevated albumin content. Higher levels of NFL correlated with worse gait, balance, wakefulness and neuropsychological performance. Preoperatively, no differences were seen in any of the CSF biomarkers between patients that improved after surgery and those that did not improve. Postoperatively, a greater improvement in gait and balance performance correlated with a more pronounced reduction in NFL. Levels of albumin, albumin ratio, neuropeptide Y, vasoactive intestinal peptide and ganglioside GD3 increased significantly after shunting in both groups. In addition, Gamma amino butyric acid increased significantly in SNPH and tau in INPH.

Conclusion

We conclude that a number of biochemical changes occur after shunt surgery, but there are no marked differences between the SNPH and INPH patients. The results indicate that NFL may be a marker that can predict a surgically reversible state in NPH.

Ventricular cerebrospinal fluid neurofilament protein levels decrease in parallel with white matter pathology after shunt surgery in normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is characterized by disturbed cerebrospinal fluid (CSF) dynamics and white matter lesions (WML). Although the morphology of these lesions is described, little is known about the biochemistry. Our aim was to explore the relationship between ventricular CSF markers, periventricular WML and postoperative clinical outcome in patients with NPH. We analysed lumbar and ventricular concentrations of 10 CSF markers, 12 clinical symptoms and signs, magnetic resonance imaging (MRI) periventricular white matter hyperintensities (PVH) and ventricular size before and 3 months after shunt surgery in 35 patients with NPH. Higher ventricular CSF neurofilament protein (NFL), an axonal marker, correlated with more extensive PVH. A larger postoperative reduction in NFL correlated with larger reduction in PVH and a more pronounced overall improvement. Albumin ratio, HMPG, NPY, VIP and GD3 increased postoperatively whereas NFL, tau and HVA decreased. Variations in ventricular size were not associated with CSF concentrations of any marker. We conclude that NPH is characterized by an ongoing periventricular neuronal dysfunction seen on MRI as PVH. Clinical improvement after shunt surgery is associated with CSF changes indicating a restitution of axonal function. Other biochemical effects of shunting may include increased monoaminergic and peptidergic neurotransmission, breakdown of blood brain barrier function, and gliosis.

Sulfatide increases adiponectin and decreases TNF-alpha, IL-6, and IL-8 in human adipose tissue in vitro

Type 2 diabetes is associated with decreased levels of the glycosphingolipid sulfatide, as well as a state of low-grade inflammation. Sulfatide is reported to have anti-inflammatory properties in other cell-types. In the present study, the effects of sulfatide on adipokine (adiponectin, TNF-alpha, IL-6, and IL-8) production in human adipose tissue (AT) was investigated in vitro. Isolated human adipocytes and AT cultures were incubated with sulfatide isolated from pig brain [sulfatide containing a variety of fatty acids or isoforms of sulfatide with defined, saturated fatty acids with 16 (C16:0) or 24 (C24:0) carbon atoms]. Adiponectin production was increased 50-80%, by all sulfatide preparations. Only the C16:0 isoform decreased TNF-alpha, IL-6, and IL-8 production 20-30%. The C16:0 sulfatide has been shown to activate potassium channels in beta-cells, and glibenclamide, an ATP-sensitive K+-(KATP) channel blocker, reversed the C16:0-induced decrement in stimulated TNF-alpha, IL-6, and IL-8 release in adipocytes. Glibenclamide on its own was without effect on the production of adiponectin, TNF-alpha, IL-6, and IL-8. In conclusion, this study shows that, sulfatide exerts anti-inflammatory effects in human adipocytes and AT in vitro. Accordingly, the reported low serum levels of sulfatide in patients with type 2 diabetes might be of importance in relation to the chronic low-grade inflammatory state found in this disease.

Uptake of the glycosphingolipid sulfatide in the gastrointestinal tract and pancreas in vivo and in isolated islets of Langerhans

Background

The glycosphingolipid sulfatide has previously been found in several mammalian tissues, but information on the uptake of exogenously administered sulfatide in different organs in vivo is limited. In pancreatic beta cells, sulfatide has been shown to be involved in insulin processing and secretion in vitro. In this study, we examined the uptake of exogenously administered sulfatide and its distribution to the pancreatic beta cells. This might encourage future studies of the function(s) of sulfatide in beta cell physiology in vivo. Radioactive sulfatide was given orally to mice whereafter the uptake of sulfatide in the gastrointestinal tract and subsequent delivery to the pancreas was examined. Sulfatide uptake in pancreas was also studied in vivo by i.p. administration of radioactive sulfatide in mice, and in vitro in isolated rat islets. Isolated tissue/islets were analysed by scintillation counting, autoradiography and thin-layer chromatography-ELISA.

Results

Sulfatide was taken up in the gastrointestinal tract for degradation or further transport to other organs. A selective uptake of short chain and/or hydroxylated sulfatide fatty acid isoforms was observed in the small intestine. Exogenously administered sulfatide was found in pancreas after i.p, but not after oral administration. The in vitro studies in isolated rat islets support that sulfatide, independently of its fatty acid length, is endocytosed and metabolised by pancreatic islets.

Conclusion

Our study supports a selective uptake and/or preservation of sulfatide in the gastrointestinal tract after oral administration and with emphasises on pancreatic sulfatide uptake, i.p. administration results in sulfatide at relevant location.

C16:0 sulfatide inhibits insulin secretion in rat beta-cells by reducing the sensitivity of KATP channels to ATP inhibition

Sulfatide (3'-sulfo-beta-galactosyl ceramide) is a glycosphingolipid present in mammalians in various fatty acid isoforms of which the saturated 16 carbon-atom length (C16:0) is more abundant in pancreatic islets than in neural tissue, where long-chain sulfatide isoforms dominate. We previously reported that sulfatide isolated from pig brain inhibits glucose-induced insulin secretion by activation of ATP-sensitive K+ channels (K(ATP) channels). Here, we show that C16:0 sulfatide is the active isoform. It inhibits glucose-stimulated insulin secretion by reducing the sensitivity of the K(ATP) channels to ATP. (The half-maximal inhibitory concentration is 10.3 and 36.7 micromol/l in the absence and presence of C16:0 sulfatide, respectively.) C16:0 sulfatide increased whole-cell K(ATP) currents at intermediate glucose levels and reduced the ability of glucose to induce membrane depolarization, reduced electrical activity, and increased the cytoplasmic free Ca2+ concentration. Recordings of cell capacitance revealed that C16:0 sulfatide increased Ca2+-induced exocytosis by 215%. This correlated with a stimulation of insulin secretion by C16:0 sulfatide in intact rat islets exposed to diazoxide and high K+. C24:0 sulfatide or the sulfatide precursor, beta-galactosyl ceramide, did not affect any of the measured parameters. C16:0 sulfatide did not modulate glucagon secretion from intact rat islets. In betaTC3 cells, sulfatide was expressed (mean [+/-SD] 0.30 +/- 0.04 pmol/microg protein), and C16:0 sulfatide was found to be the dominant isoform. No expression of sulfatide was detected in alphaTC1-9 cells. We conclude that a major mechanism by which the predominant sulfatide isoform in beta-cells, C16:0 sulfatide, inhibits glucose-induced insulin secretion is by reducing the K(ATP) channel sensitivity to the ATP block.

Clusterin in cerebrospinal fluid: Analysis of carbohydrates and quantification of native and glycosylated forms

Clusterin is suggested to be involved in the pathogenesis of Alzheimer's disease. Clusterin expression is increased in brain tissue in affected regions of Alzheimer patients, and intense clusterin staining is found in both senile plaques and in neuronal and glia cells. In contrast, the cerebrospinal fluid level of clusterin in Alzheimer patients has, thus far, been found unchanged. Clusterin is a glycosylated protein, and an alteration of its glycosylation in Alzheimer's disease might influence accurate quantification in cerebrospinal fluid through interference of antibody binding to the protein. Using enzymatic deglycosylation of clusterin isolated from cerebrospinal fluid, we found that the carbohydrates attached to clusterin were of the N-linked type and sialic acids. Based on this finding, cerebrospinal fluid samples from Alzheimer patients (n=99) and controls (n=39) were analysed. The samples were treated with peptide: N-glycanase F, cleaving off N-linked carbohydrates, and clusterin was quantified before and after deglycosylation using a new sandwich enzyme-linked immunosorbent assay. Clusterin was significantly increased in Alzheimer patients, in both native (7.17+/-2.43 AU versus 5.73+/-2.09 AU; p=0.002), and deglycosylated samples (12.19+/-5.00 AU versus 9.68+/-4.38 AU; p=0.004). Deglycosylation led to increased measured levels of clusterin by 70% (p<0.001) in Alzheimer patients and 67% (p<0.001) in controls. These findings indicate that glycosylation of proteins may interfere with their quantification. The results show that clusterin is significantly increased in cerebrospinal fluid from Alzheimer patients as a group, supporting that clusterin might be involved in the pathogenesis of Alzheimer's disease. However, the individual clusterin levels overlap between the two groups, and thus cerebrospinal fluid clusterin measurement is not suitable as a biochemical marker in the diagnosis of Alzheimer's disease.

Temporarily controlled HIV-1 replication after intravenous immunoglobulin treatment of Guillain-Barré syndrome

HIV establishes a latent infection in resting CD4(+) T-lymphocytes. A possible strategy to eliminate cellular reservoirs in long-lived, HIV-1-infected quiescent CD4(+) T-lymphocytes might be to add T-cell-activating agents to potent antiretroviral therapy. In this report we describe a patient with Guillain-Barré syndrome treated with high dose intravenous immunoglobulin (IVIG) in addition to antiretroviral therapy. A transiently increased viral load and immunoactivation during the IVIG treatment suggest activation of latently infected cells and increased turnover rate of the latent viral reservoir. HIV replication was controlled with plasma viral load <20 copies/ml, for at least 3 months after antiretroviral treatment interruption. CSF neural markers reflecting degenerative processes in the brain during the symptomatic period and follow-up were also analysed. Very high CSF sulfatide concentrations were found indicating that the pathology involves severe demyelination.We hypothesize that IVIG in this case contributed to an activation of latently infected cells, which led to a transient increase in plasma HIV-1 RNA during the IVIG treatment and a long period of undetectable viral load after antiretroviral treatment interruption. Further, this is the first time, to our knowledge, that detailed CSF findings are described in HIV-1 associated GBS.

Involvement of sulfatide in beta cells and type 1 and type 2 diabetes

Mammalian tissues express beta-isoforms of glycosphingolipids and, among these, sulfatide (sulphated galactosylceramide) is present in the beta cells, and it is here that the short fatty acid chain (C16) isoform is predominately found. In vitro studies have shown that sulfatide preserves insulin crystals and facilitates insulin monomerisation under certain biochemical conditions. It also activates beta cell potassium channels and moderates insulin secretion. Anti-sulfatide antibodies are seen in type 1 diabetes, and immunological presentation of glycosphingolipids by the non-classical CD1 molecules has recently been reported. It is via this mechanism that alpha-galactosylceramide and sulfatide are able to influence the innate immune system and inhibit autoimmunity, possibly through regulatory natural killer T cells. Administration of sulfatide substantially reduces the incidence of diabetes in non-obese diabetic mice and prevents antigen-induced experimental autoimmune encephalomyelitis in wild-type mice. Sulfatide has specific anti-inflammatory properties, increasing the number of CD3+CD25+ regulatory T cells and reducing production of several cytokines, including TNF-alpha. Patients with type 2 diabetes have low serum concentrations of sulfatide, and some animal models of type 2 diabetes have low pancreatic expression of C16:0 sulfatide; administration of this increases insulin secretion and improves first-phase insulin response in Zucker fatty rats. Glycosphingolipids in general, and sulfatide in particular, appear relevant to both type 1 and type 2 diabetes.

Low serum concentration of sulfatide and presence of sulfated lactosylceramid are associated with Type 2 diabetes. The Skaraborg Project

AIMS

The glycosphingolipid sulfatide (sulfated galactosyl-ceramide) increases exocytosis of beta-cell secretory granules, activates K(ATP)-channels and is thereby able to influence insulin secretion through its presence in the islets. A closely related compound, sulfated lactosylceramide (sulf-lac-cer), is present in the islets during fetal and neonatal life when, as in Type 2 diabetes, insulin is secreted autonomically without the usual first phase response to glucose. The aim was to examine whether serum concentrations of these glycolipids are associated with Type 2 diabetes.

METHODS

A case-control study, comprising 286 women and 283 men, was designed using a population-based sample of patients with Type 2 diabetes and a population survey.

RESULTS

Low serum concentrations of sulfatide were associated with Type 2 diabetes, independent of traditional risk factors for diabetes in a sex-specific analysis: odds ratio (OR) 2.1 (95% confidence interval 1.1, 3.9) in men, and 2.3 (1.2, 4.3) in women, comparing the lowest and the highest tertiles. Type 2 diabetes was also associated with detectable amounts of sulf-lac-cer in serum: OR 1.7 (0.9, 3.4) in men, and 7.6 (3.8, 15.2) in women. After adjustment for confounding from other diabetes risk factors, these associations remained basically unchanged. The connections between sulfatide and Type 2 diabetes, and sulf-lac-cer and Type 2 diabetes were independent of each other. Insulin resistance (HOMA-IR) was negatively correlated with sulfatide concentration and positively correlated with sulf-lac-cer (both P < 0.0001, independently).

CONCLUSIONS

We report a new, robust and highly significant independent association between Type 2 diabetes and serum concentrations of sulfatide in both sexes, and sulf-lac-cer in females. The associations were also independent of other known diabetes risk factors.

Accumulation of sulfatide in neuronal and glial cells of arylsulfatase A deficient mice

Arylsulfatase A (ASA) degrades sulfatide, seminolipid and lactosylceramide sulfate, glycolipids recognized by the Sulph I antibody although sulfatide is considered the main antigen. Sulfatide is myelin associated but studies have shown a minor distribution also in non-myelin forming cells. The aim of this work was to further study sulfatide in neurons and astrocytes by immunohistochemistry, facilitated by investigation of tissue from adult ASA deficient (ASA -/-) mice. Cells with a low presence of sulfatide might be detected due to lack of ASA activity and accumulation of Sulph I antigens. Sulfatide positive astrocytes and neurons were more numerous and intensely stained in ASA -/- mice, demonstrating a sulfatide accumulation compared to controls. Sulph I staining was especially increased in the molecular layer of cerebellum, in which Purkinje cell dendrites displayed an altered morphology, and in layer IV-VI of cerebral cortex. In hippocampus, immunostaining was found in neuronal cytoplasm in ASA -/- but in nuclear membranes of control mice. We observed a gray matter astrogliosis, which appeared to be associated to sulfatide accumulation. In addition, the developmental change (<20 months) of Sulph I antigens, galactosylceramide, phospholipids and cholesterol were followed by lipid analyses which verified sulfatide and seminolipid accumulation in adult ASA -/- mice, although no lactosylceramide sulfate could be detected. In addition to demonstrating sulfatide in neurons and astrocytes, this study supports the value of ASA -/- mice as a model for metachromatic leukodystrophy and suggests that accumulation of sulfatide beyond myelin might contribute to the pathology of this disease.

Structural characterization of the GM1 ganglioside by infrared multiphoton dissociation, electron capture dissociation, and electron detachment dissociation electrospray ionization FT-ICR MS/MS

Gangliosides play important biological roles and structural characterization of both the carbohydrate and the lipid moieties is important. The FT-ICR MS/MS techniques of electron capture dissociation (ECD), electron detachment dissociation (EDD), and infrared multiphoton dissociation (IRMPD) provide extensive fragmentation of the protonated and deprotonated GM1 ganglioside. ECD provides extensive structural information, including identification of both halves of the ceramide and cleavage of the acetyl moiety of the N-acetylated sugars. IRMPD provides similar glycan fragmentation but no cleavage of the acetyl moiety. Cleavage between the fatty acid and the long-chain base of the ceramide moiety is seen in negative-ion IRMPD but not in positive-ion IRMPD of GM1. Furthermore, this extent of fragmentation requires a range of laser powers, whereas all information is available from a single ECD experiment. However, stepwise fragmentation by IRMPD may be used to map the relative labilities for a series of cleavages. EDD provides the alternative of electron-induced fragmentation for negative ions with extensive fragmentation, but suffers from low efficiency as well as complication of data analysis by frequent loss of hydrogen atoms. We also show that analysis of MS/MS data for glycolipids is greatly simplified by classification of product ion masses to specific regions of the ganglioside based solely on mass defect graphical analysis.

In vivo administration of the C16:0 fatty acid isoform of sulfatide increases pancreatic sulfatide and enhances glucose-stimulated insulin secretion in Zucker fatty (fa/fa) rats

BACKGROUND

Sulfatide is present in the secretory granules of beta cells and has been shown, in vitro, to be involved in insulin processing and secretion. Of particular interest is one of the major sulfatide isoforms in the beta cells, the C16:0 fatty acid isoform, which has been shown to be involved in insulin crystal preservation in vitro. The aim of this study was to investigate the ability of C16:0 fatty acid isoform of sulfatide to affect insulin secretion and/or action and glycaemic control in the adipogenic 'prediabetic' Zucker rat.

METHODS

The C16:0 sulfatide was administered to Zucker rats for 10 weeks, and fasting levels of plasma insulin and glucose were measured as well as levels after an intravenous (i.v.) glucose load. In addition, the sulfatide expression, examined by thin-layer chromatography-enzyme-linked immunosorbent assay and mass spectrometry, in the pancreas of C16:0 sulfatide-treated Zucker rats was compared to controls.

RESULTS

The in vivo treatment of Zucker rats with C16:0 sulfatide resulted in significantly elevated glucose-stimulated insulin secretion (60-80% increase, p < 0.05), without significant changes in glucose tolerance. The treatment was associated with an ameliorated first-phase insulin response (3-4-fold, p = 0.009, 0.016) and a 60% increase of pancreatic sulfatide content (p = 0.001), possible by an uptake of C16:0 sulfatide. The fasting hyperinsulinaemia and blood glucose levels were unchanged.

CONCLUSIONS

The treatment with C16:0 sulfatide elevates glucose-stimulated insulin secretion and enhances sulfatide content in the pancreas of Zucker rats.

Structural membrane alterations in Alzheimer brains found to be associated with regional disease development; increased density of gangliosides GM1 and GM2 and loss of cholesterol in detergent-resistant membrane domains

The formation of neurotoxic beta-amyloid fibrils in Alzheimer's disease (AD) is suggested to involve membrane rafts and to be promoted, in vitro, by enriched concentrations of gangliosides, particularly GM1, and the cholesterol therein. In our study, the presence of rafts and their content of the major membrane lipids and gangliosides in the temporal cortex, reflecting late stages of AD pathology, and the frontal cortex, presenting earlier stages, has been investigated. Whole tissue and isolated detergent-resistant membrane fractions (DRMs) were analysed from 10 AD and 10 age-matched control autopsy brains. DRMs from the frontal cortex of AD brains contained a significantly higher concentration (micromol/micromol glycerophospholipids), of ganglioside GM1 (22.3 +/- 4.6 compared to 10.3 +/- 6.4, p <0.001) and GM2 (2.5 +/- 1.0 compared to 0.55 +/- 0.3, p <0.001). Similar increases of these gangliosides were also seen in DRMs from the temporal cortex of AD brains, which, in addition, comprised significantly lower proportions of DRMs. Moreover, these remaining rafts were depleted in cholesterol (from 1.5 +/- 0.2 to 0.6 +/- 0.3 micromol/micromol glycerophospholipids, p <0.001). In summary, we found an increased proportion of GM1 and GM2 in DRMs, and accelerating plaque formation at an early stage, which may gradually lead to membrane raft disruptions and thereby affect cellular functions associated with the presence of such membrane domains.

Beta-galactosylceramide increases and sulfatide decreases cytokine and chemokine production in whole blood cells

The glycosphingolipid sulfatide and its immediate precursor beta-galactosylceramide (GalCer) are present in the pancreatic beta-cell in equimolar concentrations and may play a role in islet pathology. Previous studies of mononuclear cells have shown that sulfatide tends to decrease and GalCer tends to increase the production of proinflammatory cytokines. In this study we investigated the influence of various isoforms of sulfatide on the production of cyto- and chemokines and tested whether the opposing effects of GalCer and sulfatide could counter one another in competition assays. PHA-, LPS-, or unstimulated whole blood cultures were incubated with 30 microg/ml of native sulfatide (isolated from pig brains), C:16:0 and C:24:0 analogues of sulfatide, or native GalCer preparations. After 24 h, the supernatant levels of proinflammatory cytokines and chemokines were quantitated by ELISA. The general trend was for the sulfatides to lower the production of the cytokines, and for GalCer to increase it. In competition assays, native sulfatide dampened the stimulatory effects of GalCer but did not abolish cytokine release; GalCer, on the other hand, nullified the effect of native sulfatide at a ratio of four sulfatide molecules to one GalCer molecule. C:16:0 sulfatide appeared to have a stronger effect than C:24:0 sulfatide. The C:16:0 analogue decreased IL-1beta, IL-6, TNF-alpha, MIP-1alpha and IL-8 to 3-56% of control values (P < 0.05-0.01), while GalCer increased their production 2- to 10-fold (P < 0.01). In conclusion, sulfatide decreases the in vitro production of proinflammatory cytokines, whereas GalCer has the opposite effect.

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.

Gangliosides as therapeutic targets for cancer

Gangliosides, sialic acid-containing glycosphingolipids, have engendered great interest for more than 20 years in the search for target molecules of relevance for tumour growth and formation of metastases and as potential targets for immunotherapy. These molecules show large quantitative and structural variability, which is related to cell type and developmental stage. Their potential role in the formation of tumour metastases was suggested from data supporting that they are involved in cell growth regulation and in cell-cell and cell-matrix adhesion. Moreover, gangliosides are expressed on the cell surface and thereby are accessible for antibodies or other ganglioside-binding molecules to induce cell death, inhibit cell growth and/or inhibit formation of tumour metastasis. All tumours exhibit aberrant ganglioside expression. This includes overexpression of normal ganglioside constituents, which appears to be common among various tumours, and expression of gangliosides not found in normal adult tissue but often found during fetal development. The ganglioside composition of melanoma cells has been found to correlate with their metastatic potential and also to be selectively expressed in cells of a tumour mass and invading tumour cells. Passive immunotherapy using murine or murine/human chimeric monoclonal antiganglioside antibodies in their native form or combined with various effector molecules has been investigated. However, the vaccination strategy using native or structurally modified tumour-associated gangliosides in combination with adjuvants is currently the dominant method in clinical trials. The outcomes reported so far vary between type of tumour and treatment strategies. However, we believe that targeting gangliosides is as promising as any other immune therapeutic strategy, and basic research as well as clinical trials utilising new aspects is encouraged.

Differences in cerebrospinal fluid dynamics do not affect the levels of biochemical markers in ventricular CSF from patients with aqueductal stenosis and idiopathic normal pressure hydrocephalus

To compare levels of biochemical markers in ventricular cerebrospinal fluid (vCSF) between patients with aqueductal stenosis (AS) and idiopathic normal pressure hydrocephalus (INPH) and relate these results to clinical outcome after surgery. Neurofilament light protein, tau protein, sulfatide, vasoactive intestinal peptide (VIP), neuropeptide PYY (NPY) and CSF/serum albumin ratio were measured in vCSF from 18 consecutive AS and 19 consecutive INPH patients. Clinical outcome was evaluated after surgery by standardized indices. The levels of markers were related to clinical outcome. No differences in any of the markers were found between AS and INPH patients. The concentration of sulfatide and albumin ratio correlated inversely with psychometric improvement, whilst VIP and NPY correlated inversely with improvement in alertness. The similar levels of biochemical markers in vCSF from AS and INPH patients indicate similarities in pathophysiology and turnover rate of vCSF despite differences in CSF dynamics. High albumin ratio and sulfatide concentrations in vCSF in hydrocephalus patients have negative implications for surgical outcome and might indicate concomitant cerebrovascular disorder.

Selective lack of the C16:0 fatty acid isoform of sulfatide in pancreas of type II diabetic animal models

Sulfatide (3'-sulfogalactosyl-ceramide) is a glycosphingolipid mainly located in the nervous system, but has also been found in the islets of Langerhans. Previous studies have suggested that sulfatide is involved in insulin processing and secretion. In this study, sulfatide expression and metabolism in pancreas and isolated islets of the type II diabetes models, ob/ob- and db/db mouse, was investigated using TLC-ELISA, metabolic labelling and electron microscopy. As in non-diabetic Lewis rat and human pancreas, sulfatide was located in secretory granules of the beta cells. However, the type II diabetic animal models and their background strains had an altered sulfatide expression, involving the lack of the C16:0 sulfatide fatty acid isoform, compared to non-diabetic Lewis rat, BALB/c mouse and human pancreatic tissue, in which the two dominating pancreatic sulfatide isoforms C16:0 and C24:0 are expressed. Correspondingly, in isolated ob/ob islets, sulfatide synthesis excluded the production of C16:0 sulfatide. Insulin administration to ob/ob mouse, which lowers beta cell activity, resulted in significantly increased sulfatide expression in pancreas (p=0.0003), but still no expression of the C16:0 sulfatide isoform. In vitro, the C16:0 sulfatide was shown to be the isomer involved in the preservation of insulin crystals. Thus, it is hypothesized that the selection of sulfatide isomers in pancreas might be a genetic factor contributing to disease development in type II diabetic animal models.

Normal pressure hydrocephalus triggers intrathecal production of TNF-alpha

Normal pressure hydrocephalus (NPH) is associated with periventricular white matter lesions and demyelination. The aim of the present study was to examine the cerebrospinal fluid (CSF) levels of tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine mediating myelin damage, in patients with NPH. TNF-alpha levels were analyzed by ELISA and measured before and after shunt operation in 35 patients with NPH. The levels of this cytokine were related to the symptomatology and to magnetic resonance imaging (MRI) verified white matter lesions. They were also related to intrathecal levels of sulfatide, a marker for white matter degradation and to levels of neurofilament, a marker for neuronal degeneration. The preoperative levels of TNF-alpha were increased in the CSF of NPH patients compared to controls, and correlated to the levels of sulfatide. The intrathecal TNF-alpha levels were higher in NPH patients with impairment of wakefulness than in those without this symptom. The preoperative TNF-alpha levels were significantly correlated to the improvement of psychometrical test scores, and of wakefulness and to the overall improvement of the patients following shunt operation. Importantly, shunt operation led to complete disappearance of intrathecal TNF-alpha. We conclude that NPH is correlated with intrathecal TNF-alpha production being reversed following shunt operation in parallel with the clinical improvement. The positive correlation between preoperative TNF-alpha and sulfatide levels in the CSF suggest that intrathecal TNF-alpha may contribute to the damage of the white matter known to occur in patients with NPH.

Correlation between intrathecal sulfatide and TNF-alpha levels in patients with vascular dementia

OBJECTIVES

Subcortical vascular dementia (SVD) is associated with white matter lesions and demyelination. The aim of the present study was to examine the cerebrospinal fluid (CSF) levels of TNF-alpha, a proinflammatory cytokine mediating myelin damage, in SVD patients. The intrathecal TNF-alpha levels were related to the clinical symptoms of dementia, as well as to intrathecal levels of sulfatide, a marker of white matter degradation, and of neurofilament, a marker of neuronal degeneration.

METHODS

CSF levels of TNF-a, sulfatide and neurofilament were all analyzed by immunoenzymatic procedures in 17 patients with SVD and in 26 healthy controls.

RESULTS

The intrathecal concentration of TNF-alpha was significantly increased in SVD patients compared to healthy controls (p = 0.0001). The intrathecal levels of TNF-alpha were significantly correlated (r = 0.6, p = 0.02) to the levels of sulfatide, but not to the levels of neurofilament, (r = 0.08, NS).

CONCLUSIONS

We have demonstrated intrathecal production of TNF-alpha in SVD patients. The correlation between TNF-a and sulfatide levels in the CSF suggests that this apoptosis-inducing cytokine leads to the death of oligodendrocytes, thereby contributing to white matter degeneration, a hallmark of SVD.

Developmental expression of the type I diabetes related antigen sulfatide and sulfated lactosylceramide in mammalian pancreas

Previous studies have shown that sulfatide is present and functionally involved in beta cells, and that anti-sulfatide antibodies (ASA) exist during development of type I diabetes mellitus. To further explore the possible role of sulfatide in type I diabetes, developmental expression was examined in human pancreas and in pancreas of the type I diabetes models BB rat and NOD mouse compared to Lewis rat and BALB/c mouse, respectively. Sulfatide was not only expressed in adult pancreas, but also in human fetal and rodent neonatal pancreas, i.e., during the growing period of the immunological self. Sulfatide had a different expression pattern in human beings and rodents, concerning both the amounts of sulfatide and expression during development. There was no change in the sulfatide fatty acid isoform expression during development. The pancreatic expression of another sulfated glycosphingolipid, sulfated lactosylceramide, indicated that this molecule is a potential fetal/neonatal marker, which was further expressed in the type I diabetic models. In conclusion, these findings give further support to the possibility that sulfatide is a relevant autoantigen in type I diabetes and that sulfated lactosylceramide might function as a potential risk factor for disease development, at least in the animal models.

Quality assurance for cerebrospinal fluid protein analysis: international consensus by an Internet-based group discussion

A group of neurologists and clinical neurochemists representing twelve countries worked towards a consensus on laboratory techniques to improve the quality of analysis and interpretation of cerebrospinal fluid (CSF) proteins. Consensus was approached via a virtual Lotus Notes-based TeamRoom. This new approach respecting multicultural differences, common views, and minority opinions, is available in http://www.teamspace.net/ CSF, presenting the implicit, complementary version of this explicit, printed consensus. Three key recommendations were made: CSF and (appropriately diluted) serum samples should be analyzed together in one analytical run, i.e., with reference to the same calibration curve. Results are evaluated as CSF/serum quotients, taking into account the non-linear, hyperbolic relation between immunoglobulin (Ig)- and albumin-quotients rather than using the linear IgG index or IgG synthesis rate. Controls should include materials with values within the reference ranges (IgM: 0.5-1.5 mg/l; IgA: 1-3 mg/l; IgG: 10-30 mg/l and albumin: 100-300 mg/l). The physiological, methodological and clinical significance of CSF/serum quotients is reviewed. We confirmed the previous consensus on oligoclonal IgG, in particular the usefulness of the five typical interpretation patterns. The group compared current external and internal quality assurance schemes and encouraged all members to maintain national or local traditions. Values for acceptable imprecision in the CSF quality assurance are proposed.

Patients with insulin-dependent diabetes but not those with non-insulin-dependent diabetes have anti-sulfatide antibodies as determined with a new ELISA assay

BACKGROUND

In sera from newly diagnosed insulin-dependent diabetes mellitus patients (IDDM type 1) autoantibodies occur against different antigen determinants often shared with neural tissues. The role of these autoantibodies in the disease process is not yet clarified but they can be used as a diagnostic tool in the detection of IDDM patients.

METHODS

We have analysed the occurrence of sulfatide autoantibodies in serum from patients with type 1 diabetes (n = 20), individuals with pre-type 1 diabetes (n = 6), patients with type 2 diabetes (n = 32) and controls (n = 43). The method used for the determination of the autoantibodies was a newly developed microtitre-ELISA assay utilizing a complex of sulfatide-albumin as the ligand.

RESULTS

The new assay procedure for serum sulfatide autoantibodies showed good reproducibility. The total (day-to-day) imprecision based on analyses of three different serum samples with positive titres varied between 11 and 14% during an assay period of 6 months. None of the controls (0/43) had positive titres of sulfatide antibodies. Of the patients with type 1 diabetes, 85% displayed positive titres of anti-sulfatide antibodies while none of the type 2 patients did so. All individuals with pre-type 1 diabetes had positive titres of sulfatide antibodies.

CONCLUSIONS

We conclude that sulfatide autoantibodies in serum can be reproducibly assayed by the newly developed microtitre-ELISA procedure. Elevated titres of sulfatide autoantibodies are a constant finding in newly diagnosed type 1 patients.

Sulfatide controls insulin secretion by modulation of ATP-sensitive K(+)-channel activity and Ca(2+)-dependent exocytosis in rat pancreatic beta-cells

The glycosphingolipid sulfatide is present in secretory granules and at the surface of pancreatic beta-cells, and antisulfatide antibodies (ASA; IgG1) are found in serum from the majority of patients with newly diagnosed type 1 diabetes. Here we demonstrate that sulfatide produced a glucose- and concentration-dependent inhibition of insulin release from isolated rat pancreatic islets. This inhibition of insulin secretion was due to activation of ATP-sensitive K(+)-(K(ATP)) channels in single rat beta-cells. No effect of sulfatide was observed on whole-cell Ca(2+)-channel activity or glucose-induced elevation of cytoplasmic Ca(2+) concentration. It is interesting that sulfatide stimulated Ca(2+)-dependent exocytosis determined by capacitance measurements and depolarized-induced insulin secretion from islets exposed to diazoxide and high external KCl. The monoclonal sulfatide antibody Sulph I as well as ASA-positive serum reduced glucose-induced insulin secretion by inhibition of Ca(2+)-dependent exocytosis. Our data suggest that sulfatide is important for the control of glucose-induced insulin secretion and that both an increase and a decrease in the sulfatide content have an impact on the secretory capacity of the individual beta-cells.

Expression of the myelin and oligodendrocyte progenitor marker sulfatide in neurons and astrocytes of adult rat brain

Sulfatide is a myelin component of the central (CNS) and peripheral nervous system (PNS) and is used extensively to identify oligodendrocyte progenitor cells. We have explored sulfatide expression in CNS gray matter (cerebellum, cerebral cortex, and hippocampus) and the PNS in adult rats using an anti-sulfatide antibody (Sulph I) and confocal microscopy. Biochemical analyses revealed two Sulph I antigens, sulfatide and seminolipid; sulfatide was present at about five times higher concentration, and the affinity of Sulph I for sulfatide was 2.5 times higher than that for seminolipid. Thus sulfatide was considered the dominant antigen. We found Sulph I immunostaining, in addition to that in myelinated areas in subpopulations of astrocytes and neurons. Astrocyte Sulph I staining was localized to the cell bodies and in some cases also to the processes. In the cerebellum, some Sulph I-positive astrocytes corresponded to Golgi epithelial cell bodies. We also found Sulph I staining in neuronal cell bodies, which in some neurons was clearly localized to the cytoplasm and in others to the nuclear membrane. Sulph I immunostaining in the PNS was located in the myelin sheath and paranodal end segments. These results demonstrate the expression of sulfatide in cell types other than oligodendrocytes and Schwann cells, showing that sulfatide is not a selective marker for adult oligodendrocyte progenitor cells. Moreover, these findings show that sulfatide is localized also to intracellular compartments and indicate that other roles of sulfatide in astrocytes and neurons, compared to myelin, might be considered.

Sulfatide is associated with insulin granules and located to microdomains of a cultured beta cell line

Previous studies using pancreas from various mammals and freshly isolated islets from rat pancreas have provided evidence supporting possible involvement of the glycosphingolipid sulfatide in insulin processing and secretion. In this study, sulfatide expression and metabolism in the beta cell line RINr1046-38 (RIN-38), commonly used as a model for beta cell functional studies, were investigated and compared with previous findings from freshly isolated islets. RIN-38 cells expressed similar amounts (2.7 +/- 1.1 nmol/mg protein, n = 19) of sulfatide as isolated rat islets and also followed the same metabolic pathway, mainly through recycling. Moreover, in agreement with findings in isolated islets, the major species of sulfatide isolated from RIN-38 cells contained C16:0 and C24:0 fatty acids. By applying subcellular isolations and electron microscopy and immunocytochemistry techniques, sulfatide was shown to be located to the secretory granules, the plasma membrane and enriched in detergent insoluble microdomains. In the electron microscopy studies, Sulph I staining was also associated with mitochondria and villi structures. In conclusion, RIN-38 cells might be an appropriate model, as a complement to isolated islets where the amount of material often limits the experiments, to further explore the role of sulfatide in insulin secretion and signal transduction of beta cells.

White matter changes in normal pressure hydrocephalus and Binswanger disease: specificity, predictive value and correlations to axonal degeneration and demyelination

OBJECTIVES

To analyse the diagnostic and prognostic value of periventricular hyperintensity (PVH) and deep white matter hyperintensity (DWMH) magnetic resonance imaging (MRI) changes and their relation to symptoms and cerebrospinal fluid (CSF) markers of demyelination (sulphatide) and axonal degeneration [neurofilament triplet protein (NFL)] in a large series of patients with normal pressure hydrocephalus (NPH) and Binswanger disease (BD).

MATERIALS AND METHODS

PVH and DWMH were determined by a semi-automatic segmentation method on T2-weighted images in 29 patients with NPH and 17 patients with BD. CSF analyses, psychometric testing and quantification of balance, gait and continence were performed in all patients and also postoperatively in NPH patients.

RESULTS

No MRI variable could identify NPH or BD patients. Abundant PVH and DWMH preoperatively correlated with improvement in gait, balance and psychometric performance after shunt surgery (P < 0.05). CSF sulphatide correlated positively with the amount of DWMH (P < 0.05) while NFL was correlated to both PVH and DWMH (P < 0.05). Abundant PVH correlated with poor psychometric performance while DWMH correlated with gait disturbance (P < 0.05). Postoperative reduction in PVH correlated with improvement in gait, balance and psychometric performance.

CONCLUSION

In spite of a refined quantification method, NPH and BD patients exhibited similar MRI changes. MRI had a predictive value in NPH patients. DWMH might relate to demyelination and PVH to neuronal axonal dysfunction. NPH and BD share the major part of symptoms and MRI changes, indicating a common pathophysiological pattern, and we raise the question of how to treat BD patients.

Treatment with sulfatide or its precursor, galactosylceramide, prevents diabetes in NOD mice

Sulfatide (3'sulfogalactosylceramide) is a glycosphingolipid present within the nervous system and in the islets of Langerhans. Anti-sulfatide antibodies have been observed in both pre-diabetic and newly diagnosed type 1 diabetic patients. The aim of this study was to test in vivo, the therapeutic effect of sulfatide on the development of diabetes in the NOD mouse. In four separate experiments diabetogenic splenocytes from newly diabetic NOD mice were injected iv into 7-8 week old irradiated (700R) female NOD mice (4-10 million cells/mouse). Each experiment consisted of four treatment groups to which the mice were randomly divided: 1) sulfatide; 2) galactosylceramide (the precursor to sulfatide without sulfate); 3) GM1, a glycosphingolipid negatively charged as sulfatide but with a different sugar composition; and 4) phosphate buffered saline (PBS). The mice received 100 microg glycosphingolipid iv on the day of cell transfer and 1-3 times thereafter at four day intervals, and were screened for diabetes three times a week the next 52 days. Among all the 35 sulfatide-treated mice 54% became diabetic compared to 93 % of 43 PBS-treated animals (p < 0.00001). Correspondingly, galactosylceramide reduced diabetes incidence to 52% (25 mice, p < 0.00001). On the other hand, 86% of GM1-treated mice (n=28) became diabetic indicating that no effect was obtained by this glycosphingolipid. In two experiments in which less spleen cells were transferred (4-5 mill.) and glycosphingolipids were given 4 times, 35% of the sulfatide-treated animals (n = 17) developed diabetes compared to 85% of PBS-treated mice (n = 20, p < 0.001). A robust proliferative response to sulfatide, but none to GM1, was observed when spleen cells were rechallenged with glycosphingolipid in vitro. Thus, like insulin and GAD, sulfatide is able to prevent diabetes in NOD mice.

Glycosphingolipid antibodies in serum in patients with sciatica

STUDY DESIGN

Serum antibody titers against 10 different glycosphingolipids were investigated by enzyme-linked immunosorbent assay in three groups of patients: patients with acute sciatica (Group IA, radicular pain for 32 +/- 36 days, n = 68), a subgroup of these patients 4 years later (Group IB, n = 23), and patients undergoing lumbar discectomy because of disc herniation (Group II, n = 37).

OBJECTIVES

To investigate the immunologic response in sciatica patients by analyzing circulating autoantibodies against glycosphingolipids, molecules highly expressed in cells from the nervous system, and the possible correlation of such antibodies to clinical and imaging findings as well as to subjective symptoms.

SUMMARY OF BACKGROUND DATA

The titers of glycosphingolipid antibodies are elevated in neurologic diseases with autoimmune stimulation such as Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy.

METHODS

Antiglycosphingolipid antibodies were assayed by a microtiter enzyme-linked immunosorbent assay method. Antibody titers were related to a healthy population by a method that judges all positive results (positive result = patient sera/pooled blood donor serum >2, at titer 1/400) as indicating a pathologic condition.

RESULTS

Increased levels of circulating antibodies against one or more glycosphingolipids were detected in 71% of patients with acute sciatica, in 61% of sciatica patients at a 4-year follow-up visit (eight antigens analyzed) and in 54% in patients undergoing discectomy. These frequencies were somewhat higher than, and in the last group similar to, those reported for generalized nervous system disorders with autoimmune involvement. In the acute sciatica patients, positive neurologic findings were associated with increased levels of two of the examined antibodies: 3'LM1 (immunoglobulin M and/or immunoglobulin G), P = 0.023, and GD1a (immunoglobulin M), P = 0.017.

CONCLUSION

The presence of glycosphingolipid antibodies in patients with sciatica and disc herniation suggests an activation of the immune system and thus a process possibly involved in the pathophysiology of sciatica. The autoimmune response was not limited to antibodies against one specific glycosphingolipid target; rather, an overall increase in autoantibodies against nervous system-associated glycosphingolipids was observed. These results encourage further studies of the pathophysiologic and clinical relevance of autoimmune responses in patients with sciatica and disc herniation.

Dynamic association of human insulin receptor with lipid rafts in cells lacking caveolae

Cholesterol-sphingolipid rich plasma membrane domains, known as rafts, have emerged as important regulators of signal transduction. The adipocyte insulin receptor (IR) is localized to and signals via caveolae that are formed by polymerization of caveolins. Caveolin binds to IR and stimulates signalling. We report that, in liver-derived cells lacking caveolae, autophosphorylation of the endogenous IR is dependent on raft lipids, being compromised by acute cyclodextrin-mediated cholesterol depletion or by antibody clustering of glycosphingolipids. Moreover, we provide evidence that IR becomes recruited to detergent-resistant domains upon ligand binding and that clustering of GM2 ganglioside inhibits IR signalling apparently by excluding the ligand-bound IR from these domains. Our results indicate that, in cells derived from liver, an important insulin target tissue, caveolae are not required for insulin signalling. Rather, the dynamic recruitment of the ligand-bound IR into rafts may serve to regulate interactions in the initiation of the IR signalling cascade.

Bone marrow stem cell-based gene transfer in a mouse model for metachromatic leukodystrophy: effects on visceral and nervous system disease manifestations

Arylsulfatase A (ASA) knockout mice represent an animal model for the lysosomal storage disease metachromatic leukodystrophy (MLD). Stem cell gene therapy with bone marrow overexpressing the human ASA cDNA from a retroviral vector resulted in the expression of high enzyme levels in various tissues. Treatment partially reduces sulfatide storage in livers exceeding 18 ng ASA/mg tissue, while complete reduction was observed in livers exceeding 50 ng ASA/mg tissue. This corresponds to about 80% and 200% of normal enzyme activity. Similar values seem to apply for kidney. A partial correction of the lipid metabolism was detectable in the brain where the galactoerebroside/sulfatide ratio, which is diminished in ASA-deficient mice, increased upon treatment. This partial correction was accompanied by amelioration of neuropathology; axonal cross-sectional areas, which are reduced in deficient mice, were significantly increased in the saphenic and sciatic nerve but not in the optic nerve. Behavioral tests suggest some improvement of neuromotor abilities. The gene transfer did not delay the degeneration occurring in the acoustic ganglion of ASA-deficient animals. The limited success of the therapy appears to be due to the requirement of unexpected high levels of ASA for correction of the metabolic defect.

The glioma-associated gangliosides 3'-isoLM1, GD3 and GM2 show selective area expression in human glioblastoma xenografts in nude rat brains

This work describes the in vivo expression and distribution of glioma-associated gangliosides (GD3, GM2, 3'-isoLM1) in a novel human brain tumour nude rat xenograft model. In this model, the tumours, which are established directly from human glioblastoma biopsies, show extensive infiltrative growth within the rat brain. This model therefore provides an opportunity to study ganglioside expression not only within the macroscopic tumour, but also in brain areas with tumour cell infiltration. The ganglioside expression was studied by confocal microscopy of immunostained brain sections using antiganglioside monoclonal antibodies. Xenografts from four human glioblastoma multiformes were established in rats and the brains removed after 3-4 months. Ganglioside GD3 was expressed in the tumour parenchyma while ganglioside 3'-isoLM1 was more abundantly expressed in the periphery of the tumour associated with areas of tumour cell invasion. GM2 expression was only seen in one tumour, where it was located within the main tumour mass. Double staining with a pan antihuman monoclonal antibody (3B4) and the antiganglioside monoclonal antibodies confirmed that the ganglioside expression was associated with tumour cells. This work supports the concept of different biological roles for individual gangliosides and indicates that antibodies or ligands directed against GD3 and 3'-isoLM1 might be complementary when applied in the treatment of human glioblastomas.

Normal levels of clusterin in cerebrospinal fluid in Alzheimer's disease, and no change after acute ischemic stroke

The protein clusterin has been suggested to be involved in the pathogenesis of Alzheimer's disease (AD). Its expression is increased in brain regions affected by AD pathology, and to elucidate if there is a concomitant increase of clusterin also in the cerebrospinal fluid (CSF) in different neurological disorders, CSF samples from patients with AD, vascular dementia (VAD), Parkinson's disease (PD), and controls were analysed. Also longitudinal (five occasions) samples from patients with acute stroke were analysed, to follow any degenerative/regenerative phase after acute brain damage. However, there were no changes in CSF-clusterin levels from patients in AD, VAD, PD or acute stroke, as compared to controls. The increase of clusterin in brain tissue is suggested to reflect a regenerative response process, which here is shown not to be followed by a concomitant increase in the CSF. Thus, CSF-clusterin can not be used as an indicator or a diagnostic marker for AD.

Sulfatide promotes the folding of proinsulin, preserves insulin crystals, and mediates its monomerization

Sulfatide is a glycolipid that has been associated with insulin-dependent diabetes mellitus. It is present in the islets of Langerhans and follows the same intracellular route as insulin. However, the role of sulfatide in the beta cell has been unclear. Here we present evidence suggesting that sulfatide promotes the folding of reduced proinsulin, indicating that sulfatide possesses molecular chaperone activity. Sulfatide associates with insulin by binding to the insulin domain A8--A10 and most likely by interacting with the hydrophobic side chains of the dimer-forming part of the insulin B-chain. Sulfatide has a dual effect on insulin. It substantially reduces deterioration of insulin hexamer crystals at pH 5.5, conferring stability comparable to those in beta cell granules. Sulfatide also mediates the conversion of insulin hexamers to the biological active monomers at neutral pH, the pH at the beta-cell surface. Finally, we report that inhibition of sulfatide synthesis with chloroquine and fumonisine B1 leads to inhibition of insulin granule formation in vivo. Our observations suggest that sulfatide plays a key role in the folding of proinsulin, in the maintenance of insulin structure, and in the monomerization process.

Patients with Primary brain tumours have elevated serum titres of antibodies to the myelin glycolipid sulphatide

Primary and metastatic brain tumours may result in an altered exposure of normal cellular components to the immune system inducing an immune response measurable in autoantibodies. One potential immunogenic molecule is sulphatide, the major acidic glycolipid in myelin. Thirty-eight sera from 31 patients with primary and metastatic brain tumours have, therefore, been analyzed for the presence of antisulphatide antibodies by an ELISA performed on thin layer chromatography plates. Twenty-eight of the thirty-eight sera (74%) showed a positive antibody titre to sulphatide. The antibody titres were significantly higher (p < 0.01) in sera from patients with primary brain tumours than in sera from those with metastases. The study lends support to the possibility that antisulphatide antibodies could contribute to tissue damage and this might facilitate the invasive growth in primary brain tumours by demyelination. However, the pathogenic significance of these autoantibodies remains to be further elucidated.

Haptoglobins as markers of blood-CSF barrier dysfunction: the findings in normal CSF

Cerebrospinal fluid from 39 healthy individuals showed evidence for increasing blood-CSF barrier permeability with age, and confirmed that haptoglobins are more sensitive but less predictive markers of barrier permeability than total protein. Haptoglobin (Hp) species were identified by polyacrylamide gel electrophoresis followed by immunoblotting. Hp 1-1 (35 A, 85 kDa) was detected in all (9/9) subjects who exhibited this phenotype. Hp 2-1 (42 A, 120 kDa) was detected in 53% (8/15) of subjects in whom Hp 2-1 was the phenotype. Hp 2-2 (54 A, 160 kDa) was detected in only 20% (3/15) of subjects who exhibited this phenotype. The likelihood of detecting any haptoglobin species corresponded to the molecular size and the consequent resistance offered by the barrier. Among younger subjects aged < or =45 years, a significant difference in incidence occurred between the two smaller species Hp 1-1 and Hp 2-1. However, among those aged >45, the significant difference in incidence was between the two larger species Hp 2-1 and Hp 2-2. The incidence of detection among those with Hp 2-1 phenotypes was higher in the older age group. The increased likelihood of detecting haptoglobins with age is in keeping with the notion that barrier function is compromised by age, and also indicates that Hp 2-1 and Hp 2-2 are sensitive markers of barrier function. The appreciable incidence of haptoglobins in normal CSF, even of the larger species, suggests reservation in assuming that their presence signifies barrier damage.

IL-10 and IFN-gamma in Guillain-Barré syndrome. Network Members of the Swedish Epidemiological Study Group

Guillain-Barré syndrome (GBS) is an acute inflammatory disease affecting myelin and axons of the peripheral nervous system (PNS). GBS is considered to be caused by breakdown of tolerance to autoantigens of the PNS. The involvement of cytokines in GBS and in relation to treatment with high dose intravenous immunoglobulin (IvIg) is incompletely known. We studied the temporal profiles of IL-10 and IFN-gamma-secreting blood mononuclear cells (MNC) over the course of GBS, using enzyme-linked immunospot (ELISPOT) assays. Pretreatment levels of blood MNC spontaneously secreting IL-10 were higher in the acute phase of GBS than in control patients with aseptic meningitis, other neurological diseases, diabetic neuropathy and healthy subjects. Levels of IFN-gamma-secreting blood MNC were not increased over the course of GBS. Patients treated with IvIg had lower numbers of IL-10-secreting MNC compared to untreated patients. High levels of IL-10-secreting MNC correlated with serum anti-ganglioside IgM antibody levels, and with neurophysiological signs of axonal damage. The present data suggests that IFN-gamma is not involved in GBS pathogenesis, and IL-10 being up-regulated in the early phase of GBS and associated with axonal damage, may have a pathogenetic role in GBS.

Monoclonal anti-GD3 antibodies selectively inhibit the proliferation of human malignant glioma cells in vitro

The frequently occurring alteration of ganglioside expression in tumor cells has been implicated to play a role in the uncontrolled growth of these cells; antibodies to such gangliosides might affect tumor cell growth. We have studied the effect of IgM monoclonal antibodies to two glioma-associated gangliosides, GD3 and GM2, on cell proliferation of four human glioma cell lines and one renal tumor cell line. Of the two anti-ganglioside antibodies tested, only the anti-GD3 antibody resulted in a significant (p<0.005) inhibition of cell proliferation as measured by thymidine incorporation and Brd-U labeling, after 24h incubation. The effect was not dependent on any serum factor and no increased cell death was observed. All cell lines contained higher or similar amounts of GM2 than GD3, and both antigens were shown to be expressed on the cell surface and accessible to antibodies. The selective effect of anti-GD3 antibodies as contrasted to the inactivity of anti-GM2 antibodies suggests a possible role for ganglioside GD3 in tumor cell proliferation.

CSF sulfatide distinguishes between normal pressure hydrocephalus and subcortical arteriosclerotic encephalopathy

OBJECTIVES

To examine the CSF concentrations of molecules reflecting demyelination, neuronal and axonal degeneration, gliosis, monoaminergic neuronal function, and aminergic and peptidergic neurotransmission in a large series of patients with normal pressure hydrocephalus (NPH) or subcortical arteriosclerotic encephalopathy (SAE), to elucidate pathogenic, diagnostic, and prognostic features.

METHODS

CSF concentrations of glycosphingolipid (sulfatide), proteins (neurofilament triplet protein (NFL), glial fibrillary acidic protein (GFAP)), neuropeptides (vasoactive intestinal peptide (VIP), 4-aminobutyric acid (GABA)), and monoamines (homovanillic acid (HVA), 5-hydroxy-indoleacetic acid (5-HIAA), 4-hydroxy-3-methoxyphenylglycol (HMPG)) were analysed in 43 patients with NPH and 19 patients with SAE. The diagnoses of NPH and SAE were based on strict criteria and patients with NPH were subsequently operated on. Twelve clinical variables, psychometric tests measuring perceptual speed, accuracy, learning, and memory and a psychiatric evaluation were performed in all patients and before and after a shunt operation in patients with NPH.

RESULTS

The CSF sulfatide concentration was markedly increased in patients with SAE (mean 766, range 300-3800 nmol/l) compared with patients with NPH (mean 206, range 50-400 nmol/l) (p<0.001). 5-HIAA, GABA, and VIP in CSF were higher in patients with SAE than in patients with NPH. The patients with NPH with cerebrovascular aetiology had higher sulfatide concentrations and a poorer outcome after shunt surgery than patients with NPH with other aetiologies.

CONCLUSIONS

The pathogenesis of the white matter changes in NPH and SAE is different and ischaemic white matter changes can be a part of the NPH state. The markedly increased CSF sulfatide concentrations in patients with SAE indicate ongoing demyelination as an important pathophysiological feature of SAE. The CSF sulfatide concentration distinguished between patients with SAE and those with NPH with a sensitivity of 74% and a specificity of 94%, making it an important diagnostic marker.

Immunostaining of ganglioside GD1b, GD3 and GM1 in rat cerebellum: cellular layer and cell type specific associations

We have studied the cellular distribution of gangliosides GD1b, GD3 and GM1 in rat cerebellum by immunostaining, using monoclonal antibodies and confocal microscopy. Antibodies against astroglial, neuronal and synaptic vesicle associated molecules were used for colocalization analyses. In the gray matter, the anti-GD1b antibody stained thin strands in the molecular layer (ML), interpreted as Bergman glia fibers based on colocalized staining with anti-glial fibrillary acidic protein (GFAP). The neuropil in the granule (GL) and Purkinje (PL) cell layers was also anti-GD1b positive. The anti-GD3 antibody stained the ML, the neuropil in the GL and PL and also the granule and Purkinje cell bodies, appearing intracytoplasmically and vesicle associated. Anti-GD1b and anti-GD3 staining in the GL glomeruli were colocalized with anti-synaptophysin staining. The anti-GM1 antibody stained cell bodies in the ML but they could not be characterized in colocalization experiments. The GL and PL were not stained with the anti-GM1 antibody. In the white matter, different staining patterns were seen for the gangliosides, the anti-GM1 staining being the most intense. This study shows cellular layer and cell type specific associations of the investigated gangliosides and localization of GD1b and GD3 at synaptic sites, warranting further studies on their role in synaptic mechanisms.

Cerebrospinal fluid antibodies directed against neuron-associated gangliosides in HIV-1 infection

BACKGROUND

Loss of synapses and neurons is a common finding in HIV-1 infection. Since the in vivo infection of neurons by HIV-1 is limited, indirect factors are likely to contribute to the pathogenesis.

PATIENTS AND METHODS

We have analyzed cerebrospinal fluid (CSF) and serum samples from 25 HIV-1-infected individuals (nine with and 16 without CNS complications) and 19 HIV-negative controls with aseptic meningitis or viral encephalitis, for the presence of antibodies directed against the neuron-associated gangliosides GM1, GD1a and GD1b.

RESULTS

Positive antibody titers to > or =1 of the gangliosides were found in 13/25 HIV-1-infected patients in CSF and in 17/25 in serum. Significant correlations were found between the presence and titers of CSF antibodies against GM1, GD1a, and GD1b. Six out of nine patients with, and 3/16 without neurological complications (p < 0.05) had positive CSF titers of > or = 1 of the ganglioside antibodies combined with negative serum titers, indicating intrathecal antibody production. In contrast, only 1/19 controls had detectable anti-ganglioside antibodies in the CSF.

CONCLUSION

The results should be interpreted with caution and CSF anti-ganglioside antibody production might be a part of a non-specific intrathecal polyclonal immunoactivation. Nevertheless, autoantibodies directed against neuron-associated gangliosides might be involved in the neuropathogenesis in HIV-1 disease.

Measurement of apolipoprotein E (apoE) in cerebrospinal fluid

Apolipoprotein E (apoE) is a protein involved in transport of lipids and has been implicated to play an important role in regeneration after nerve injury. Determination of apoE in cerebrospinal fluid (CSF) thus have a potential interest when studying different forms of brain damage and as a marker of ongoing regenerative processes in the brain. However, previous studies on CSF-ApoE in Alzheimer's disease (AD) have given inconclusive results. Such inconsistent results might be related to confounding factors interfering with sample handling and/or analyses, which have not been fully elucidated. We therefore examined different potential confounding factors for analyses of apoE in CSF and also developed a new enzyme linked immunosorbent assay (ELISA). The hydrophobic character of ApoE resulted in adsorption to different types of test tubes commonly used for collection of CSF at lumbar puncture, resulting in falsely low levels. This makes CSF handling critical, especially if samples are taken in different types of tubes, or is transferred to new tubes. Taking this confounding factors in consideration and analysing patient and control CSF handled in the same way and using the new ELISA, we could confirm our previous finding of reduced levels of ApoE in AD, (3.4 +/- 1.3 mg/l) compared with controls (4.5 +/- 2.7 mg/l) (p = 0.045). Both in the AD and in the control group, higher levels of CSF-ApoE was found in individuals possessing the ApoE4 alleles. Our results support that CSF-ApoE is reduced in AD, and that handling of CSF is a critical factor, which may explain the discrepant results from previous studies. Differences in the amount of patients and controls possessing the ApoE4 allele included might also increase the variance between different studies.