Global glycosphingolipid analysis in urine and plasma of female Fabry disease patients.

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by deficiency of α-galactosidase-A, which results in accumulation of the glycosphingolipid (GSL) globotriaosylceramide (Gb3). Gb3 and globotriaosylsphingosine (lyso-Gb3) levels in plasma and urine are used routinely for diagnosis and treatment monitoring. FD female patients are problematic to diagnose and to predict when to begin treatment. Further biomarkers are needed to detect pre-symptomatic females that will develop the chronic symptoms associated with FD. A LC-MS/MS glycosphingolipidomic assay was developed to measure lyso-Gb3 and GSLs from the lysosomal GSL degradation pathway, including globoside (Gb4), Gb3, ceramide dihexosides (CDH) and ceramide monohexosides (CMH). We analysed plasma and urine from a cohort of Fabry patients, grouped according to clinical symptoms and independent of treatment status (asymptomatic females n = 18, symptomatic females n = 18, males n = 27 and control urines n = 16 and control plasmas n = 58). Multivariate and subsequent univariate analysis showed urine GSLs which had highest significance in identifying asymptomatic females were total levels of CDH, in particular the long chain isoforms C22:1,C22:0,C22:1-OH,C22:0-OH,C24:2,C24:0,C24:2-OH,C24:1-OH,C24:0-OH,C26:0 which likely represent Galabiosylceramide (Ga2) and not lactosylceramide. These long chain Ga2 isoforms were found to be 5-fold elevated and more statistically significant (p < 0.0001) than plasma lyso-Gb3 (p < 0.01) in identifying asymptomatic Fabry female patients. Receiver operating characteristic curve analysis gave an area under the curve of 0.82 (p = 0.001) for lyso-Gb3 and 0.88 (p = 0.0006) for long-chain CDH isoforms indicating the long chain CDH isoforms were as, if not more, a better biomarker for the identification of female FD patients.

Altered phospholipid molecular species and glycolipid composition in brain, liver and fibroblasts of Zellweger syndrome.

We studied the altered molecular species of lipids in brain and liver tissues, and fibroblasts from patients with Zellweger syndrome (ZS). ZS cerebellum samples contained a higher amount of sphingomyelin with shorter chain fatty acids compared to that in normal controls. The amount of phosphatidylethanolamine (PE) was less than half of that in controls, with the absence of the PE-type of plasmalogen. Gangliosides were accumulated in the brains and fibroblasts of ZS patients. To investigate whether or not impaired beta-oxidation of very long chain fatty acids and/or plasmalogen synthesis affects glycolipids metabolism, RNAi of peroxisomal acylCo-A oxidase (ACOX1) and glyceronephosphate O-acyltransferase (GNPAT) was performed using cultured neural cells. In neuronal F3-Ngn1 cells, ACOX1 and GNPAT silencing up-regulated ceramide galactosyltransferase (UGT8) mRNA expression, and down-regulated UDP-glucose ceramide glucosyltransferase (UGCG). These results suggest that both impaired beta-oxidation of very long chain fatty acids and plasmalogen synthesis affect glycolipid metabolism in neuronal cells.