myelin-basic-protein and Leukodystrophy--Globoid-Cell

Infantile Krabbe disease results in the accumulation of lipid-raft-associated galactosylsphingosine (psychosine), demyelination, neurodegeneration and premature death. Recently, axonopathy has been depicted as a contributing factor in the progression of neurodegeneration in the Twitcher mouse, a bona fide mouse model of Krabbe disease. Analysis of the temporal-expression profile of MBP (myelin basic protein) isoforms showed unexpected increases of the 14, 17 and 18.5 kDa isoforms in the sciatic nerve of 1-week-old Twitcher mice, suggesting an abnormal regulation of the myelination process during early postnatal life in this mutant. Our studies showed an elevated activation of the pro-apoptotic protease caspase 3 in sciatic nerves of 15- and 30-day-old Twitcher mice, in parallel with increasing demyelination. Interestingly, while active caspase 3 was clearly contained in peripheral axons at all ages, we found no evidence of caspase accumulation in the soma of corresponding mutant spinal cord motor neurons. Furthermore, active caspase 3 was found not only in unmyelinated axons, but also in myelinated axons of the mutant sciatic nerve. These results suggest that axonal caspase activation occurs before demyelination and following a dying-back pattern. Finally, we showed that psychosine was sufficient to activate caspase 3 in motor neuronal cells in vitro in the absence of myelinating glia. Taken together, these findings indicate that degenerating mechanisms actively and specifically mediate axonal dysfunction in Krabbe disease and support the idea that psychosine is a pathogenic sphingolipid sufficient to cause axonal defects independently of demyelination.

Topics: Animals; Animals, Newborn; Axons; Caspase 3; Cell Line, Transformed; Ceramides; Disease Models, Animal; DNA Fragmentation; Dose-Response Relationship, Drug; Enzyme Activation; Leukodystrophy, Globoid Cell; Mice; Mice, Inbred C57BL; Mice, Neurologic Mutants; Motor Neurons; Myelin Basic Protein; Neural Conduction; Neurofilament Proteins; Peripheral Nervous System Diseases; Protein Isoforms; Psychosine; Sciatic Nerve; Spinal Cord

Low vitamin D level is a risk factor for various late-onset CNS demyelinating disorders. We investigated whether vitamin D deficiency influences disease in twitcher mice (GALC(twi/twi) ; twi), a murine model of Krabbe disease (KD), an inherited disorder caused by galactocerebrosidase (GALC) deficiency that leads to psychosine accumulation, oligodendrocyte (OL) loss, and CNS demyelination. We found that the in situ 1,25-dihydroxyvitamin D3 level was reduced, with a parallel increase in the expression of inflammatory cytokines and vitamin D-catabolizing enzymes in the brains of KD and twi mice compared with age-matched controls. Pups maintained on milk from lactating heterozygous (GALC(twi/+) ) mothers that were fed a vitamin D3-supplemented diet until weaning and then fed a vitamin D3-supplemented diet demonstrated delayed body weight loss and development of disease in twi mice. This delayed the onset of tremors and locomotor disabilities that eventually impacted the life span of twi mice (50 ± 2 days). Accordingly, the expression of antioxidant enzymes was increased with delayed psychosine accumulation, lipid peroxidation, and inflammatory response that eventually protected CNS myelin and axonal integrity in twi mice. In vitro studies revealed that 1,25-dihydroxyvitamin D3 enhances antioxidant defenses in OLs deficient for GALC or incubated with psychosine. Together these data provide the first evidence that vitamin D deficiency affects disease development in twi mice and that vitamin D3 supplementation has the potential to improve the efficacy of KD therapeutics.

Topics: 25-Hydroxyvitamin D3 1-alpha-Hydroxylase; Age Factors; Animals; Animals, Newborn; Brain; Calcitriol; Cells, Cultured; Cholecalciferol; Cytokines; Disease Models, Animal; Galactosylceramidase; Glutathione; Humans; Leukodystrophy, Globoid Cell; Mice; Mice, Mutant Strains; Myelin Basic Protein; Neuroglia; Superoxide Dismutase; Vitamin D3 24-Hydroxylase

While transplanted neural stem cells (NSCs) have been shown to hold promise for cell replacement in models of a number of neurological disorders, these examples have typically been under conditions where the host cells become dysfunctional due to a cell autonomous etiology, i.e. a 'sick' cell within a relatively supportive environment. It has long been held that cell replacement in a toxic milieu would not likely be possible; donor cells would succumb in much the same way as endogenous cells had. Many metabolic diseases are characterized by this situation, suggesting that they would be poor targets for cell replacement therapies. On the other hand, models of such diseases could prove ideal for testing the capacity for cell replacement under such challenging conditions. In the twitcher (twi ) mouse -- as in patients with Krabbe or globoid cell leukodystrophy (GLD), for which it serves as an authentic model -- loss of galactocerebrosidase (GalC) activity results in the accumulation of psychosine, a toxic glycolipid. Twi mice, like children with GLD, exhibit inexorable neurological deterioration presumably as a result of dysfunctional and ultimately degenerated oligodendrocytes with loss of myelin. It is believed that GLD pathophysiology is related to a psychosine-filled environment that kills not only host oligodendrocytes but theoretically any new cells placed into that milieu. Through the implantation of NSCs into the brains of both neonatal and juvenile/young adult twi mice, we have determined that widespread oligodendrocyte replacement and remyelination is feasible. NSCs appear to be intrinsically resistant to psychosine -- more so in their undifferentiated state than when directed ex vivo to become oligodendrocytes. This resistance can be enhanced by engineering the NSCs to over-express GalC. Some twi mice grafted with such engineered NSCs had thicker white tracts and lived 2-3 times longer than expected. While their brains had detectable levels of GalC, it was probably more significant that their psychosine levels were lower than in twi mice that died at a younger age. This concept of resistance based on differentiation state extended to human NSCs which could similarly survive within the twi brain. Taken together, these results suggest a number of points regarding cellular therapies against degenerative diseases with a prominent cell non-autonomous component: Cell replacement is possible if cells resistant to the toxic environment are employed. Furth

Topics: Animals; Animals, Newborn; Cell Differentiation; Cells, Cultured; Disease Models, Animal; Dose-Response Relationship, Drug; Galactosylceramidase; Genetic Therapy; Humans; Immunohistochemistry; Leukodystrophy, Globoid Cell; Mice; Mice, Mutant Strains; Microscopy, Electron, Transmission; Myelin Basic Protein; Myelin Sheath; Neurons; Oligodendroglia; Psychosine; Stem Cell Transplantation; Stem Cells; Transduction, Genetic

Globoid cell leukodystrophy is an autosomal recessive disease with progressive demyelination caused by a deficiency of the lysosomal enzyme galactosylceramidase. Bone marrow transplantation (BMT) is a therapeutic option for patients with late-onset disease and for patients with early onset disease that had an early diagnosis owing to an affected sibling. This therapy, however, typically is not effective for early onset disease when the diagnosis occurs after several months of life. In an effort to enable a broader range of patients to benefit from BMT, we tested whether combining substrate-reduction therapy with BMT would result in a greater benefit than either treatment alone in the twitcher mouse model of globoid cell leukodystrophy. Twitcher mice treated with L-cycloserine, an inhibitor of 3-ketodyhydrosphingosine synthase, and transplanted with 50 +/- 5 x 10(6) bone marrow cells on d 10 had a mean life-span of 112 d compared with 51 d for BMT alone (p < 0.001) or L-cycloserine alone, which was previously reported to be 56 d. L-Cycloserine treatment also was initiated neonatally to determine whether it would allow for a delayed BMT to have therapeutic value. Twitcher mice given only BMT at 18 d or only a short course of L-cycloserine died at 36 and 37 d, respectively. Twitcher mice given a short course of L-cycloserine + BMT at 18 d lived to 58 d (p = 0.0006). In conclusion, substrate-reduction therapy enhanced the value of BMT in twitcher mice, suggesting that this combination strategy might benefit patients with globoid cell leukodystrophy.

Topics: Animals; Body Weight; Bone Marrow Transplantation; Cycloserine; Glial Fibrillary Acidic Protein; Immunohistochemistry; Leukodystrophy, Globoid Cell; Mice; Mice, Inbred C57BL; Myelin Basic Protein; Rhombencephalon

Bone marrow transplantation (BMT) has therapeutic value for twitcher (globoid cell leukodystrophy) mice, which suffer from a genetic deficiency of the lysosomal enzyme galactosylceramidase that leads to progressive demyelination and early death. Preliminary investigations indicated that a semiallogeneic BMT resulted in graft vs. host disease (GVHD) in twitcher mice but not normal mice. Increased production of the cytokine IL-6 has been demonstrated in twitcher mice, and it has been linked with induction of GVHD. We investigated the effects of BMT in twitcher/IL-6 deficient mice and compared these findings with those from transplanted twitcher and control mice. After a semiallogeneic BMT, 11.4% of controls died within few weeks while the rest survived >100 days without GVHD. In contrast, 85% of the transplanted twitcher mice died by 70 days and 65% developed clinical signs of GVHD, e.g., alopecia and weight loss. In transplanted twitcher/IL-6 deficient mice, only 21% died by Day 70, none had alopecia, and 23% had weight loss. There was no difference in the onset day and severity of twitching between twitcher and twitcher/IL-6 deficient mice after BMT. In transplanted twitcher/IL-6 deficient mice, there was improvement of BBB integrity and a decrease in globoid cell number compared with nontransplanted twitcher/IL-6 deficient mice. In summary, these results demonstrate that an underlying pathology like globoid cell leukodystrophy leads to activation of GVHD responses in a donor-host combination that would not normally induce GVHD. Furthermore, IL-6 seems to play a key role because a deficiency of IL-6 results in a better prognosis.

Topics: Animals; Astrocytes; beta-Galactosidase; Blood-Brain Barrier; Body Weight; Bone Marrow Transplantation; Brain; Demyelinating Diseases; Female; Gliosis; Graft vs Host Disease; Immunohistochemistry; Interleukin-6; Lectins; Leukodystrophy, Globoid Cell; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Neurologic Mutants; Minor Histocompatibility Antigens; Myelin Basic Protein; Serum Albumin; Survival Rate

The expression of IL-6 is greatly enhanced in the twitcher mouse (S. M. LeVine and D. C. Brown, 1997, J. Neuroimmunol. 73, 47-56), which is an authentic animal model of globoid cell leukodystrophy (Krabbe's disease). In order to investigate the role of IL-6 in this disease, twitcher/IL-6-deficient mice were generated and the pathology was compared between them and regular twitcher mice. Twitcher/IL-6-deficient mice had a more severe disease than regular twitcher mice: they had an earlier onset day of twitching, a greater number of PAS-positive cells, a greater susceptibility to LPS, an exaggerated gliotic response around some vessels, an elevated level of TNF-alpha, and a compromised blood-brain barrier, which was evaluated by three independent measures. This latter finding indicates that IL-6 plays a role in maintaining the integrity of the BBB, and it raises the possibility that IL-6 functions in a similar manner in other diseases of the CNS. LPS was found to greatly shorten the life of twitcher and twitcher/IL-6-deficient mice compared to genotyped-matched saline-injected mice. This result indicates that a proinflammatory condition can exacerbate an underlying CNS pathology, which could help explain why some leukodystrophy patients display their initial symptoms following a fever or blow to the head.

Topics: Animals; Blood-Brain Barrier; Brain; Crosses, Genetic; Disease Progression; Escherichia coli; Glial Fibrillary Acidic Protein; Interleukin-6; Lectins; Leukodystrophy, Globoid Cell; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Neurologic Mutants; Motor Activity; Myelin Basic Protein; Rhombencephalon; Tumor Necrosis Factor-alpha

The twitcher (twi/twi) is an authentic murine model of human globoid cell leukodystrophy (GLD), caused by a deficiency of galactosylceramidase. Similar to human GLD, the twitcher shows progressive deterioration of neurological function and its neuropathology is characterized by a collection of periodic acid-Schift stain (PAS)-positive macrophages in the areas of demyelination. However, there are some differences in the clinico-pathological aspects between human and murine GLD. We investigated the spacio-temporal progression of neuropathology in the twitcher from postnatal day (PND) 10 to 45. No clinical symptoms or neuropathological changes were apparent in twi/twi until PND 15. Generally, infiltration of macrophages, concomitant with myelin degeneration, was recognized in the cerebellar white matter and the brain stem after PND 20, then in cerebral white matter after PND 25, and in cerebral and cerebellar gray matter after PND 30. The demyelination was very severe in the radix of the 8th and the 5th cranial nerves. The neurological symptoms such as tremor, spasticity and cranial nerve dysfunction were well correlated with the progression of pathological changes. Demyelination progressed in an orderly fashion such that myelin degeneration began 10 to 20 days after the commencement of myelination in any of the given nerve fiber tracts. This suggests that there are no significant differences in the metabolism of galactocerebroside in the myelin and myelin-forming cells in individual nerve fiber tracts throughout the murine brain. Over-expression of glial fibrillary acidic protein was already present before the initiation of obvious demyelination.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Aging; Animals; Animals, Newborn; Brain; Demyelinating Diseases; Leukodystrophy, Globoid Cell; Mice; Mice, Neurologic Mutants; Myelin Basic Protein; Periodic Acid-Schiff Reaction; Spinal Cord; Time Factors

We report herein a sporadic case of the pigmentary type of orthochromatic leukodystrophy with early onset and very rapid clinical course. The patient's development was normal until 2 years old, when he experienced visual disturbance. Rapid deterioration resulted in death 1.5 years after the onset. Metachromatic leukodystrophy, globoid cell leukodystrophy and adrenoleukodystrophy were excluded by biochemical assays. Autopsy findings were compatible with the diagnosis of the pigmentary type of orthochromatic leukodystrophy. However, there were unique findings of severe neuronal loss and the collection of globoid-like cells in the interface of the gray matter and the white matter. Immunohistochemical staining of myelin basic protein, proteolipid protein and galactocerebroside demonstrated that these myelin constituents were equally preserved in the posterior column, while absent in the lateral and anterior columns of the spinal cord.

Topics: Autopsy; Brain; Child, Preschool; HLA-DR Antigens; Humans; Leukodystrophy, Globoid Cell; Male; Myelin Basic Protein; Myelin Sheath; Spinal Cord; Staining and Labeling; Tomography, X-Ray Computed

Myelinogenesis is controlled by several genes. Therefore, the study of mutations affecting myelination should provide better understanding of the assembly and maintenance of myelin, and in the case of similitude with human diseases, a direct insight into the pathogenesis of these diseases. Murine mutants can be bred readily and sequential analyses allow an examination of the dynamic processes of myelination. In this study, we have selected certain aspects of four leukodystrophies in mice. The precise mechanisms leading to the important myelin deficit observed in the jimpy mutation, a sex-linked recessive trait, are still not completely elucidated. Our results show in jimpy mice severe astrocytic alterations prior to myelin formation. Therefore, abnormalities of oligodendrocytes and possibly axons could be a secondary phenomenon. Nevertheless, a defect involving neuroglia precursor cells cannot be ruled out. At the present time, Pelizaeus-Merzbacher is a disease in which mainly oligodendrocytes appear to be altered. In consequence, our findings in jimpy mice do not support the present contention that this mutation represents a model for Pelizaeus-Merzbacher disease. We propose that the jimpy mutation could be invaluable to study cell-cell interactions at an early stage of myelinogenesis. Interest in the myelin deficient (mld) mutant derives from the specific lack of one of the major myelin constituents, myelin basic protein, and the concomitant absence of the major electron dense line during the active phase of myelin deposition in the CNS. Our present knowledge points out a defect of gene regulation involving myelin basic protein synthesis. The absence of this extrinsic membrane component made it possible to catch a glimpse of its role in the formation and maintenance of the complex structure of the myelin sheath in the CNS. Quaking mice have been considered to represent an arrest of myelinogenesis. This commonly accepted view has to be reconsidered at the light of recent morphological and biochemical findings. An abnormal processing of the myelin-associated glycoprotein could prevent the normal compaction of myelin until the animals reach adulthood. Twitcher is characterized by extensive central and peripheral demyelination and the presence of intracellular inclusions in macrophages similar to human globoid cell leukodystrophy. In both human and murine diseases, a deficiency of galactosylceramidase activity was demonstrated.(ABSTRACT TRUNCATED AT 400 WOR

Topics: Animals; Astrocytes; Axons; Brain; Child; Freeze Fracturing; Galactosylceramidase; Glial Fibrillary Acidic Protein; Humans; Inclusion Bodies; Leukodystrophy, Globoid Cell; Mice; Mice, Neurologic Mutants; Microscopy, Electron; Myelin Basic Protein; Myelin Proteins; Myelin Sheath; Nerve Fibers, Myelinated; Oligodendroglia

One case of each of the following human leukodystrophies was examined immunocytochemically with antisera against myelin basic protein (MBP), myelin associated glycoprotein (MAG) and gliofibrillary acidic protein (GFA): Metachromatic leukodystrophy (MLD), connatal adrenoleukodystrophy (ALD), sudanophilic leukodystrophy of the adult (SLD) and connatal Pelizaeus-Merzbacher disease (PMD). A case of canine globoid cell leukodystrophy (GLD) was also included under the assumption that this disease was the same in the dog as in man. It was shown that the storage process in MLD and GLD did not involve MBP or MAG and that the breakdown of myelin with the formation of fat granule cells containing droplets of neutral fat in ALD and SLS proceeds in a similar way as in experimental Wallerian degeneration. In PMD, MBP is present in the vicinity of axons not surrounded by a myelin sheath demonstrable with conventional means. The globoid cells of GLD could be demonstrated to be of non-astrocytic origin.

Topics: Adolescent; Adrenoleukodystrophy; Animals; Child, Preschool; Diffuse Cerebral Sclerosis of Schilder; Dogs; Female; Glial Fibrillary Acidic Protein; Humans; Intermediate Filament Proteins; Leukodystrophy, Globoid Cell; Leukodystrophy, Metachromatic; Male; Middle Aged; Myelin Basic Protein; Myelin Proteins; Myelin-Associated Glycoprotein