globotriaosyl-lysosphingolipid and Disease-Models--Animal

Fabry disease, an X-linked glycosphingolipid storage disorder, is caused by the deficient activity of α-galactosidase A (α-Gal A). This results in the lysosomal accumulation in various cell types of its glycolipid substrates, including globotriaosylceramide (GL-3) and lysoglobotriaosylceramide (globotriaosyl lysosphingolipid, lyso-GL-3), leading to kidney, heart, and cerebrovascular disease. To complement and potentially augment the current standard of care, biweekly infusions of recombinant α-Gal A, the merits of substrate reduction therapy (SRT) by selectively inhibiting glucosylceramide synthase (GCS) were examined. Here, we report the development of a novel, orally available GCS inhibitor (Genz-682452) with pharmacological and safety profiles that have potential for treating Fabry disease. Treating Fabry mice with Genz-682452 resulted in reduced tissue levels of GL-3 and lyso-GL-3 and a delayed loss of the thermal nociceptive response. Greatest improvements were realized when the therapeutic intervention was administered to younger mice before they developed overt pathology. Importantly, as the pharmacologic profiles of α-Gal A and Genz-682452 are different, treating animals with both drugs conferred the greatest efficacy. For example, because Genz-682452, but not α-Gal A, can traverse the blood-brain barrier, levels of accumulated glycosphingolipids were reduced in the brain of Genz-682452-treated but not α-Gal A-treated mice. These results suggest that combining substrate reduction and enzyme replacement may confer both complementary and additive therapeutic benefits in Fabry disease.

Topics: alpha-Galactosidase; Animals; Blood-Brain Barrier; Carbamates; Disease Models, Animal; Fabry Disease; Glucosyltransferases; Glycolipids; Humans; Mice; Quinuclidines; Sphingolipids; Trihexosylceramides

Fabry disease is an X-linked lysosomal storage disorder caused by mutations in the gene encoding the α-galactosidase A (α-Gal A) lysosomal enzyme, which results in globotriaosylceramide (Gb3) storage in vascular endothelial cells and different cell types throughout the body. Involvement of the kidney and heart is life threatening, and fibrosis of these organs is considered to be involved in the pathogenesis of Fabry disease. An increased concentration of deacylated Gb3 (lyso‑Gb3) in the plasma of symptomatic patients has also been suggested as a causative molecular event. To elucidate the molecular mechanisms involved in renal fibrosis in Fabry disease, the present analyzed the changes in global gene expression prior to and following Gb3 or lyso‑Gb3 treatment in two types of kidney cell lines, human proximal renal tubular epithelial (HK‑2) and mouse renal glomerular mesangial (SV40 MES 13) cells. Gb3 and lyso‑Gb3 treatment regulated the expression of 199 and 328 genes in each cell type, demonstrating a >2.0‑fold change. The majority of the biological functions of the regulated genes were associated with fibrogenesis or epithelial‑mesenchymal transition (EMT). The gene expression patterns of sphingolipid‑treated HK‑2 cells were distinguishable from the patterns in the SV40 MES 13 cells. Several genes associated with the EMT were selected and evaluated further in kidney cells and in Fabry mouse kidney tissues. In the SV40 MES 13 cells, the DLL1, F8, and HOXA11 genes were downregulated, and FOXP2 was upregulated by treatment with Gb3 or lyso‑Gb3. In the HK‑2 cells, the ADAMTS6, BEST1, IL4, and MYH11 genes were upregulated. Upregulation of the FOXP2, COL15A1, IL4, and MYH11 genes was also observed in the Fabry mouse kidney tissues. The gene expression profiles in kidney cells following the addition of Gb3 or lyso‑Gb3 revealed substrate‑specific and cell‑specific patterns. These findings suggested that Gb3 and lyso‑Gb3 lead to renal fibrosis in Fabry disease through different biochemical modulations.

Topics: ADAM Proteins; ADAMTS Proteins; Animals; Bestrophins; Calcium-Binding Proteins; Cell Line, Transformed; Chloride Channels; Disease Models, Animal; Epithelial Cells; Epithelial-Mesenchymal Transition; Eye Proteins; Fabry Disease; Gene Expression Profiling; Gene Expression Regulation; Glycolipids; Homeodomain Proteins; Humans; Intercellular Signaling Peptides and Proteins; Kidney Tubules; Male; Mesangial Cells; Mice; Mice, Transgenic; Molecular Sequence Annotation; Organ Specificity; Signal Transduction; Sphingolipids; Transcriptome; Trihexosylceramides

Fabry disease is caused by deficient activity of α-galactosidase A (GLA) and characterized by systemic accumulation of glycosphingolipids, substrates of the enzyme. To gain insight into the pathogenesis of Fabry disease based on accumulated substrates, we examined the tissue and plasma distributions of globotriaosylceramide (Gb3) isoforms, and globotriaosylsphingosine (lyso-Gb3) and its analogues in a GLA knockout mouse, a model of Fabry disease, by means of liquid chromatography-mass spectrometry and nano-liquid chromatography-tandem mass spectrometry, respectively. The results revealed that the contents of these substrates in the liver, kidneys, heart, and plasma of GLA knockout mice were apparently higher than in those of wild-type ones, and organ specificity in the accumulation of Gb3 isoforms was found. Especially in the kidneys, accumulation of a large amount of Gb3 isoforms including hydroxylated residues was found. In the GLA knockout mice, the proportion of hydrophobic Gb3 isoforms was apparently higher than that in the wild-type mice. On the other hand, hydrophilic residues were abundant in plasma. Unlike that of Gb3, the concentration of lyso-Gb3 was high in the liver, and the lyso-Gb3/Gb3 ratio in plasma was significantly higher than those in the organs. The concentration of lyso-Gb3 was apparently higher than those of its analogues in the organs and plasma from both the GLA knockout and wild-type mice. This information will be useful for elucidating the basis of Fabry disease.

Topics: alpha-Galactosidase; Animals; Chromatography, High Pressure Liquid; Disease Models, Animal; Fabry Disease; Female; Glycolipids; Isomerism; Kidney; Liver; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardium; Sphingolipids; Tandem Mass Spectrometry; Trihexosylceramides