Alterations in the composition of brain lipids in patients with Creutzfeldt-Jakob disease

Altered gene transcription linked to astrocytes and oligodendrocytes in frontal cortex in Creutzfeldt-Jakob disease

Targeted expression of genes coding for proteins specific to astrocytes, oligodendrocytes and myelin was performed in frontal cortex area 8 of Creutzfeldt-Jakob disease methionine/methionine and valine/valine (CJD MM1 and VV2, respectively) compared with controls. GFAP (glial fibrillary acidic protein) mRNA was up-regulated whereas SLC1A2 (solute carrier family 1 member 2, coding for glutamate transporter 1: GLT1), AQ4 (aquaporin 4), MPC1 (mitochondrial pyruvate carrier 1) and UCP5 (mitochondrial uncoupled protein 5) mRNAs were significantly down-regulated in CJD MM1 and CJD VV2, and GJA1 (connexin 43) in CJD VV2. OLIG1 and OLIG2 (oligodendocyte transcription factor 1 and 2, respectively), SOX10 (SRY-Box10) and oligodendroglial precursor cell (OPC) marker NG2 (neuronal/glial antigen) 2 were preserved, but GALC (coding for galactosylceramidase), SLC2A1 (solute carrier family 2 member 1: glucose transporter member 1: GLUT1) and MCT1 (monocarboxylic acid transporter 1) mRNA expression levels were significantly reduced in CJD MM1 and CJD VV2. Expression levels of most genes linked to myelin were not altered in the cerebral cortex in CJD. Immunohistochemistry to selected proteins disclosed individual variations but GFAP, Olig-2, AQ4 and GLUT1 correlated with mRNA levels, whereas GLT1 was subjected to individual variations. However, MPC1, UCP5 and MCT1 decrease was more closely related to the respective reduced neuronal immunostaining. These observations support the idea that molecular deficits linked to energy metabolism and solute transport in astrocytes and oligodendrocytes, in addition to neurons, are relevant in the pathogenesis of cortical lesions in CJD.

Plasmalogens inhibit APP processing by directly affecting γ-secretase activity in Alzheimer's disease

Lipids play an important role as risk or protective factors in Alzheimer's disease (AD). Previously it has been shown that plasmalogens, the major brain phospholipids, are altered in AD. However, it remained unclear whether plasmalogens themselves are able to modulate amyloid precursor protein (APP) processing or if the reduced plasmalogen level is a consequence of AD. Here we identify the plasmalogens which are altered in human AD postmortem brains and investigate their impact on APP processing resulting in Aβ production. All tested plasmalogen species showed a reduction in γ-secretase activity whereas β- and α-secretase activity mainly remained unchanged. Plasmalogens directly affected γ-secretase activity, protein and RNA level of the secretases were unaffected, pointing towards a direct influence of plasmalogens on γ-secretase activity. Plasmalogens were also able to decrease γ-secretase activity in human postmortem AD brains emphasizing the impact of plasmalogens in AD. In summary our findings show that decreased plasmalogen levels are not only a consequence of AD but that plasmalogens also decrease APP processing by directly affecting γ-secretase activity, resulting in a vicious cycle: Aβ reduces plasmalogen levels and reduced plasmalogen levels directly increase γ-secretase activity leading to an even stronger production of Aβ peptides.

Glycolipid and ganglioside metabolism imbalances in Huntington's disease

We have explored genome-wide expression of genes related to glycobiology in exon 1 transgenic Huntington's disease (HD) mice using a custom-designed GLYCOv2 chip and Affymetrix microarray analyses. We validated, using quantitative real-time PCR, abnormal expression levels of genes encoding glycosyltransferases in the striatum of R6/1 transgenic mice, as well as in postmortem caudate from human HD subjects. Many of these genes show differential regional expression within the CNS, as indicated by in situ hybridization analysis, suggesting region-specific regulation of this system in the brain. We further show disrupted patterns of glycolipids (acidic and neutral lipids) and/or ganglioside levels in both the forebrain of the R6/1 transgenic mice and caudate samples from human HD subjects. These findings reveal novel disruptions in glycolipid/ganglioside metabolic pathways in the pathology of HD and suggest that the development of new targets to restore glycosphingolipid balance may act to ameliorate some symptoms of HD.

Demonstration of ganglioside GD3 in human reactive astrocytes

Astrocytes are the cells that actively participate in the process of lesion repair in the central nervous system (CNS), and reactive astrocytosis of varying degrees becomes apparent with time in any pathological condition occurring in the normally developed postnatal CNS. Ganglioside GD3 (II3a(NeuAca2-8NeuAc)-LacCer, GD3) in reactive astrocytes from autopsied patients with Creutzfeldt-Jakob disease (CJD) and old cerebral infarction was investigated immunocytochemically, using mouse IgM anti-GD3 monoclonal antibody (DSG-1). Reactive astrocytes in CJD and cerebral infarction demonstrated GD3-immunoreactivity within the cytoplasm. Normal astrocytes were negative. The present data raise the possibility that GD3 in reactive astrocytes has biological implications for the properties of the cells, such as cellular motility.

A new procedure for determining ganglioside GD3 a potential glial cell activation marker in cerebrospinal fluid

Increased amounts of ganglioside GD3 [II3 (NeuAc)2-LacCer], associated with reactive gliosis, have been documented in a variety of neurodegenerative disorders. GD3 expression has also been reported in microglial cells, not only during development but also in reactive states, where the glial activation is considered to be part of the repair process. It is important to find markers in cerebrospinal fluid that will enable us to identify damage and register changes in pathological processes within the brain. A sensitive and practically applicable method for determination of GD3 ganglioside in cerebrospinal fluid has been developed. The procedure, which includes extraction, purification on silica gel and thin-layer enzyme-linked immunostaining, also allows determination of sulphatide, a marker of demyelinating processes, in the same portion of CSF. The method has been applied to CSF samples from 101 normal individuals aged 2-83 years. The GD3 concentration was found to be significantly correlated to age and reflecting the concentrations within the brain. GD3 ganglioside analysis by means of this method might be useful for studying glial changes during brain maturation as well as in brain disorders.

Occurrence of GD3 ganglioside in reactive astrocytes--an immunocytochemical study in the rat brain

Immunocytochemical study of ganglioside GD3 (II3 alpha(NeuAc alpha 2-8NeuAc)-LacCer) was performed in the cold lesions produced in the cerebral cortex of the rat brain, using mouse IgM anti-GD3 monoclonal antibody (DSG-1). Seven and 15 days after cold lesioning, GD3-like immunoreactivity was observed in reactive astrocytes. Thirty and 50 days after cold lesioning, GD3-like immunoreactivity was observed in the cells that formed glial scars. Normal astrocytes were not immunoreactive. Therefore, it is possible that GD3 may play an important role in the astrocytic functions required for the process of repair of edematous lesions in the central nervous system.

Abnormal glycosphingolipid metabolism in the nervous system of galactosialidosis

In an autopsy case of galactosialidosis, GM3, GM2, GM1, and GD1a were accumulated in sympathetic and spinal ganglia and grey matter of the spinal cord. Especially, the accumulations of GM3 and GM2 amounted to 41- and 86-fold increases in sympathetic ganglia, respectively, as compared to normal controls. In addition LacCer, GA2 and GA1 were accumulated in sympathetic and spinal ganglia. The accumulations of GM3 and GD1a are considered to be the result of defective lysosomal sialidase activity and the accumulation of GM1, LacCer and GA1 is also considered to be due to decreased beta-galactosidase activity in this disorder. To better understand the possible mechanism of GM2 accumulation, we determined the activity of GM2 synthesizing enzyme (GM3:UDP-GalNAc transferase), as well as hexosaminidase activity, in sympathetic ganglia, but they did not change. Abnormal ganglioside and neutral glycosphingolipid metabolism, as well as sialyloligosaccharide and sialylglycoprotein metabolism, may be involved in the pathogenesis of this disorder.

Adult pigment type (Peiffer) of sudanophilic leukodystrophy. Pathological and morphometrical studies on two autopsy cases of siblings

Two autopsy cases of siblings with the adult pigment (Peiffer) type of sudanophilic leukodystrophy (SLD), which demonstrated the full-blown stage (case 1) and early stage (case 2) of demyelination, were examined. Numerous brown pigments deposited in demyelinated cerebral areas were characterized histochemically and ultrastructurally as lipofuscin and ceroid. Under the electron microscope formation of blebs due to myelin splitting associated with deposition of multilamellar myeloid bodies within them was a prominent feature in the demyelinated cerebral areas of case 2 as compared with case 1. However, various features of myelin degradation such as thinning, partial or complete circumferential myelin loss, and deposition of electron-dense material on the interperiodic lines were found in both cases. Blebs occurred in all layers of myelin, and axons were compressed by these blebs or the hydropically swollen inner lips of oligodendroglias. Oligodendroglias were relatively well preserved in the demyelinated and nondemyelinated areas in case 2, although the cytoplasm was hydropic. Many spheroids were present in demyelinated areas and were irregularly distributed in both cases. The peripheral nerves in case 1 presented essentially the same changes as those in the brain, although those in case 2 were not affected. Morphometrically, the results showed that hypomyelination was not the mechanism for this pigment type of SLD. One possible cause may be an accelerated ageing of the metabolic process of myelin turnover.

Ganglioside GD3: structure, cellular distribution, and possible function

Insight on the function of gangliosides can emerge from knowledge of their cellular distribution. In this paper we review the structure of ganglioside GD3 and recent information on its cellular distribution. GD3 appears to be enriched in a variety of neural cell types including: reactive glia, gliomas, undifferentiated neurons, Muller glia, and oligodendroglia. Because each of these cell types share an enhanced permeability to ions and metabolites or possess properties associated with enhanced permeability, we suggest that GD3 is associated with enhanced membrane permeability. A possible function for GD3 in membrane permeability has implications for other cellular events such as metabolism, growth and interactions.

Cellular distribution of gangliosides in the developing mouse cerebellum: analysis using the staggerer mutant

The distribution of cerebellar gangliosides was studied in staggerer (sg/sg) mutant mice, where the majority of granule cells die after completing their migration across the molecular layer. In addition, the external granule cell layer in sg/sg mice persists longer than in normal mice. Moreover, in the sg/sg cerebellum, Purkinje cells are significantly reduced in number, and almost none have tertiary branchlet spines. The loss of Purkinje cells and granule cells in sg/sg mice is accompanied by an early-onset reactive gliosis that continues through adulthood. By correlating changes in ganglioside composition with the well-documented histological events of cerebellar development in normal and sg/sg mice, we obtained strong evidence for a nonrandom cellular distribution of gangliosides. The sharpest reduction in the GD1a content of sg/sg cerebellum occurred after 15 days of age, coincident with granule cell loss. GT1a, on the other hand, was significantly reduced from 15 through 150 days in the sg/sg mice. GD3 is a major ganglioside of the undifferentiated granule cell, but it becomes rapidly displaced by the more complex gangliosides with the onset of granule cell maturation. In the sg/sg mice, GD3 persisted at abnormally high levels from 15 to 28 days and then accumulated through adulthood. These findings, and those from other cerebellar mouse mutants, suggest that GD1a is enriched in granule cells and that GT1a is enriched in Purkinje cells. Our findings also suggest that GT1a is more concentrated in branchlet spines than in other regions of the Purkinje cell membrane. GT1b appears to be enriched in both granule cells and Purkinje cells, whereas GM1 appears to be enriched in myelin. Furthermore, the apparent persistence of the embryonic ganglioside GD3 in sg/sg mice results from an early-onset reactive gliosis, together with a partial retardation in granule cell maturation. The accumulation of GD3 beyond 28 days reflects the continued accretion of GD3 in reactive glia.

Cellular localization of gangliosides in the mouse cerebellum: analysis using neurological mutants

We have used genetic dissection to study the cellular localization of gangliosides in the mouse cerebellum. This method employs a series of mouse mutations that destroy specific populations of cerebellar neurons at precise stages of development. By correlating the well documented histological changes occurring in these mutants with changes in ganglioside composition, we have obtained strong evidence for a non-random cellular distribution of gangliosides. Most notably, GD1a is more enriched in granule cells that in Purkinje cells, whereas the opposite is true for GT1a. GD3, on the other hand, is heavily enriched in reactive glia and may serve as a useful biochemical marker for the presence of reactive glia in neurological disease. The continued study of gangliosides in the various mouse mutants will help elucidate their cellular localization in the CNS.

Creutzfeldt-Jakob disease in an adolescent

A 16-year-old boy was stricken with a progressive neurologic disorder characterized primarily by dementia progressing to severe neurologic debility in 12 months and death 28 months following the first symptoms. Pathologic examination showed a spongiform encephalopathy, consistent witha clinical diagnosis of Creutzfeldt-Jakob disease (CJD). The noteworthy features of the case are the age of onset, the somewhat prolonged course an the amount of white matter change. These are discussed within the frame of reference of CJD and the spongiform encephalopathies of infancy and childhood. Animal inoculation studies employing post-mortem embalmed brain as inoculum are currently in progress to determine the transmissibility of this patient's disease.

Brain glycosidases in Creutzfeldt-Jakob disease

Several glycosidase activities were measured in frontal gray matter of 4 brains from subjects affected by Creutzfeldt-Jakob disease. The changes of N-acetyl-beta-glucosaminidase, N-acetyl-beta-galactosaminidase, beta-glucosidase, alpha-fucosidase and alpha-mannosidase were not statistically significant but significant increases of beta-glucuronidase and beta-galactosidase activities were found. These results are in accordance with several reports on brain glycosidases in scrapie and Semliki Forest virus-infected brain and could explain some changes in brain glycoconjugate content previously observed in human and experimental Creutzfeldt-Jakob disease.

Neurochemical changes in Creutzfeldt-Jakob disease

A biochemical study of a case affected by Creutzfeldt-Jakob disease is reported. Changes were found in soluble and insoluble proteins, glycoproteins and mucopolysaccharides and in total lipids, glycolipids, phospholipids and gangliosides. Also CNPase, choline acetyltransferase, 5'-nucleotidase and several glycosidases have an altered activity. All these data give a complete neurochemical pattern of the changes underlying the morphological and functional alterations in this disease.

Fatty acid profiles in mental disease. Part 1. Linolenate variations in schizophrenia

Lipids were isolated from 6 patients suffering from schizophrenia and also from 6 age-matched healthy controls. The extracted lipids were fractionated into erythrocyte and plasma lipids. Column and thin-layer chromatography on silica gel were employed further to isolate the extracts into sub-classes within the major neutral and polar lipid classifications. The fatty acid composition of each sub-class was then monitored by gas chromatography after transmethylation. A significantly higher proportion of linolenic acid (18:3w3) was found in schizophrenics when compared with the controls. The change was reflected in both the neutral lipids and phospholipids from plasma and erythrocytes of the patients. On average, 8.7 +/- 2.6 and 3.9 +/- 1.5 mole % linolenate/100 mg lipid extract were obtained from the plasma of patients and healthy controls, respectively, while 8.6 +/- 2.3 and 3.0 +/- 1.2 mole/% linolenate/100 mg lipid were recorded from the red blood cells. The other fatty acids investigated did not show such significant differences between patient and healthy subject. A net increase in the amount of total fatty acid was recorded in the patients and it is thought that either linolenate alone or linolenate together with other polyunsaturated fatty acids not considered here are responsible for these observations. Correlations of these findings with the pathology of schizophrenia are discussed.

Neutral lipid and sphingolipid composition of the brain of a patient with membranous lipodystrophy

Lipids were extracted from brains of a patient with membranous lipodystrophy (ML) and three normal patients and the neutral lipid and sphingolipid constituents were investigated. The storage of a large amount of free fatty acid was observed in the ML brain, but no cholesterol ester was found. Total lipid, cholesterol and cerebroside contents were slightly decreased in the white matter of the ML brain. The composition of free and sphingolipid fatty acids did not differ between ML and normal brains.

Creutzfeldt-Jakob disease--alteration in ganglioside sphingosine in the brain of a patient

Gangliosides isolated from the brain of patients with Creutzfelt-Jakob (C-J) disease were analyzed. The ganglioside current was abnormally low, and the percentage distributions of individual gangliosides and the long-chain base compositions were abnormal. The C20-sphingosine contents of all the ganglioside fractions were low. Abnormalities in ganglioside long-chain bases in adult human brain have been reported previously only in patients with inherited metabolic disorders. These abnormalities in C-J disease seem to be closely related to the cause of the disease.