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

Abstract

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.