Glycosphingolipids in Cultured Human Skin Fibroblasts

Fibroblasts cultured from skin biopsies obtained from patients with inherited storage diseases exhibited the specific lysosomal hydrolase deficiency found in the patient's tissues. Combined thin layer and gas liquid chromatography of the glycosphingolipids isolated from such fibroblasts showed variations in the concentration of the seven glycosphingolipids found in normal fibroblasts, GL-1a, GL-1b, GL-2a, GL-3, GL-4, Gm3, and Gd3. In three diseases in which visceral accumulation of glycosphingolipid has been demonstrated, namely, Fabry's disease, lactosylceramidosis and Gaucher's disease, two to 4-fold elevations of the glycosphingolipids, GL-3, GL-2a, and GL-1a, respectively, were found in the cultured skin fibroblasts. Tracer studies with d-[U-14C]glucose demonstrated negligible catabolism of GL-3 in Fabry cells and GL-1a in Gaucher cells. The rate of synthesis and degradation of other glycosphingolipids appeared normal with the exception of GL-2a which was virtually absent from Fabry fibroblasts. Although the enzyme deficiencies characteristic of ganglioside storage (neuronal) diseases could be demonstrated in fibroblasts, Gm1 ganglioside could not be detected in two strains of fibroblasts from patients with Gm1-gangliosidosis type I. However, in two strains of fibroblasts from patients with Gm2-gangliosidosis type I (Tay-Sachs disease) there was some evidence for the presence of Gm2 and its asialo derivative. Fibroblasts from patients with inherited lipidoses which primarily affect the myelin sheath, such as globoid cell leukodystrophy and metachromatic leukodystrophy did not accumulate cerebroside (GL-1b) or sulfatide (GL-1bS) despite the fact that the specific enzyme deficiency could be readily demonstrated. The addition of large amounts of sulfatide to the medium caused storage of sulfatide in normal skin fibroblasts which was rapidly metabolized when the cells were returned to normal medium. In contrast, fibroblasts from patients with metachromatic leukodystrophy (with deficient arylsulfatase A activity) ingest but do not metabolize exogenous sulfatide. A marked abnormality of Gm3 and Gd3 catabolism was demonstrated in fibroblasts from three patients with I-cell disease, an unusual genetic disorder in which there is a generalized lysosomal hydrolase deficiency.