Early Neurodegeneration Progresses Independently of Microglial Activation by Heparan Sulfate in the Brain of Mucopolysaccharidosis IIIB Mice

BACKGROUND: In mucopolysaccharidosis type IIIB, a lysosomal storage disease causing early onset mental retardation in children, the production of abnormal oligosaccharidic fragments of heparan sulfate is associated with severe neuropathology and chronic brain inflammation. We addressed causative links between the biochemical, pathological and inflammatory disorders in a mouse model of this disease. METHODOLOGY/PRINCIPAL FINDINGS: In cell culture, heparan sulfate oligosaccharides activated microglial cells by signaling through the Toll-like receptor 4 and the adaptor protein MyD88. CD11b positive microglial cells and three-fold increased expression of mRNAs coding for the chemokine MIP1alpha were observed at 10 days in the brain cortex of MPSIIIB mice, but not in MPSIIIB mice deleted for the expression of Toll-like receptor 4 or the adaptor protein MyD88, indicating early priming of microglial cells by heparan sulfate oligosaccharides in the MPSIIIB mouse brain. Whereas the onset of brain inflammation was delayed for several months in doubly mutant versus MPSIIIB mice, the onset of disease markers expression was unchanged, indicating similar progression of the neurodegenerative process in the absence of microglial cell priming by heparan sulfate oligosaccharides. In contrast to younger mice, inflammation in aged MPSIIIB mice was not affected by TLR4/MyD88 deficiency. CONCLUSIONS/SIGNIFICANCE: These results indicate priming of microglia by HS oligosaccharides through the TLR4/MyD88 pathway. Although intrinsic to the disease, this phenomenon is not a major determinant of the neurodegenerative process. Inflammation may still contribute to neurodegeneration in late stages of the disease, albeit independent of TLR4/MyD88. The results support the view that neurodegeneration is primarily cell autonomous in this pediatric disease

Maladie de Niemann-Pick type C (caractérisation moléculaire et approche topologique et fonctionnelle de la protéine NPC2)

La maladie de Niemann-Pick type C est une neurolipidose à transmission autosomique récessive caractérisée par une séquestration de cholestérol libre et de glycolipides dans le système endo/lysosomal. Deux gènes sont impliqués : soit NPC1, soit NPC2. La protéine NPC2 (132 aa) est soluble, possède 3 sites potentiels de N-glycosylation et lie le cholestérol libre de manière spécifique. Après l'identification des mutations causales chez 12 familles, la localisation intracellulaire de la protéine NPC2, l'importance fonctionnelle des sites potentiels de N-glycosylation et l'impact des six mutations faux-sens identifiées chez les malades ont été étudiés. La protéine NPC2 est majoritairement lysosomale. Deux sites sont N-glycosylés (N58 et N135) et seule la chaîne fixée en N58 est importante pour la localisation et la fonction de la protéine NPC2. Un impact sur la fonction et la localisation de la protéine NPC2 a été retrouvé uniquement avec les mutations C47F, S67P, C93F et C99RLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Caractérisation moléculaire de la maladie de Niemann-Pick type C

LYON1-BU Santé (693882101) / SudocSudocFranceF

Dosage du globotriaosylcéramide dans l’urine

La maladie de Fabry est une maladie de surchargedue à un déficit de l’α-galactosidase A.Un traitement par enzyme de substitution estdésormais possible. Le dosage du globotriaosylcéramidedans l’urine peut être effectué parspectrométrie de masse en tandem (MS/MS).Cette technique, particulièrement sensible etspécifique, est décrite, ainsi que les résultatschez des patients atteints, des femmes hétérozygoteset des malades traités par enzyme desubstitution

Normalisation of brain spectroscopy findings in Niemann–Pick disease type C patients treated with miglustat

International audienceNiemann-Pick disease type C (NP-C) is a fatal progressive neurolipidosis involving neuronal storage of cholesterol and gangliosides. Miglustat, an inhibitor of glycosphingolipid synthesis, has been approved to treat neurological manifestations in adults and children with NP-C. This open-label observational study in adults with confirmed NP-C evaluated the efficacy of miglustat (200 mg t.i.d.) based on composite functional disability (CFD) scores and brain proton magnetic resonance spectroscopy (H-MRS) measurement of choline (Cho)/N-acetyl aspartate (NAA) ratio in the centrum ovale. Overall, 16 patients were included and received miglustat for a mean period of 30.6 months: 12 continued on miglustat throughout follow up, and 4 discontinued miglustat because of adverse effects (n = 2) or perceived lack of efficacy (n = 2). In the 'continued' subgroup, the mean (SD) annual progression of CFD scores decreased from 0.75 (0.94) before treatment to 0.29 (1.29) during the period between miglustat initiation and last follow-up. In the discontinued subgroup, CFD progression increased from 0.48 (0.44) pre-treatment to 1.49 (1.31) at last follow up (off treatment). Mean (SD) Cho/NAA ratio [normal level 0.48 (0.076)] decreased during miglustat treatment in the continued subgroup: 0.64 (0.12) at baseline (miglustat initiation), 0.59 (0.17) at 12-month follow up, and 0.48 (0.09) at 24-month follow up. Cho/NAA ratio remained relatively stable in the discontinued subgroup: 0.57 (0.15), 0.53 (0.04) and 0.55 (0.09), respectively. In conclusion, H-MRS Cho/NAA ratio might serve as an objective, quantitative neurological marker of brain dysfunction in NP-C, allowing longitudinal analysis of the therapeutic effect of miglustat

Gene therapy of the brain in the dog model of Hurler's syndrome

International audienceObjective A defect of the lysosomal enzyme α-L-iduronidase (IDUA) interrupts the degradation of glycosaminoglycans in mucopolysaccharidosis type I, causing severe neurological manifestations in children with Hurler's syndrome. Delivery of the missing enzyme through stereotactic injection of adeno-associated virus vectors coding for IDUA prevents neuropathology in affected mice. We examined the efficacy and the safety of this approach in enzyme-deficient dogs. Methods Because deficient dogs raise antibodies against IDUA in response to infusion, intracerebral vector injections were combined with an immunosuppressive regimen. Results Treatment was tolerated well. We observed broad dispersion of vector genomes in the brain of efficiently immunosuppressed dogs. The delivery of IDUA to large areas, which could encompass the entire brain, prevented glycosaminoglycan and secondary ganglioside accumulations. This condition was associated with drastic reduction of neuropathology throughout the encephalon. In contrast, vector injection combined with partial immunosuppression was associated with subacute encephalitis, production of antibodies against IDUA in brain tissues, and elimination of genetically modified cells. Interpretation Gene therapy directed to the entire brain is feasible and may be beneficial to children with Hurler's syndrome. The possibility of subacute encephalitis emphasizes the importance of preventing immune response against IDUA, a problem that needs to be considered in similar therapies for other genetic defects. Ann Neurol 2006