Progression of multiple sclerosis is associated with gender differences in glutathione S-transferase P1 detoxification pathway.

The impact of glutathione S-transferases (GSTs) detoxification pathway on complex pathogenesis and heterogeneity of clinical findings in multiple sclerosis (MS), particularly the exact correlation between indicators of clinical severity and different GST genotypes, has not yet been fully elucidated. The aim of the study was to assess the relationship between disability level in multiple sclerosis (estimated by Kurtzke Expanded Disability Status Scale), disease progression (estimated by Multiple Sclerosis Severity Score), the level of brain atrophy and lesion load (determined by MRI) and detoxification status (analyzing glutathione S-transferase P1, GSTP1, genotype profile), in a group of 58 MS patients and 68 age/gendermatched controls. The results present the first evidence on significantly higher frequency of GSTP1 C341T polymorphism (C-T transition) in healthy subjects compared to MS patients, suggesting it may act as a moderating factor in developing MS clinical phenotype. Gender-dependent distribution of the C341T polymorphism was found in both MS patients and controls, with higher frequency of C-T transition in females. In addition, preliminary data showed higher proportion of male MS patients with higher median MSSS scores, as well as lower brain atrophy level and lesion load in MS patients carrying the C341T mutation. Observed gender difference in distribution of the C341T polymorphism in MS patients, as well as in disease progression, suggests that GSTP1 detoxification pathway occurs in a gender-dependent manner and could therefore add to clinical severity in male MS patients.

Structural analysis of brain ganglioside acetylation patterns in mice with altered ganglioside biosynthesis.

Gangliosides are sialylated membrane glycosphingolipids especially abundant in mammalian brain tissue. Sialic acid O-acetylation is one of the most common structural modifications of gangliosides which considerably influences their chemical properties. In this study, gangliosides extracted from brain tissue of mice with altered ganglioside biosynthesis (St8sia1 null and B4galnt1 null mice) were structurally characterized and their acetylation pattern was analyzed. Extracted native and alkali-treated gangliosides were resolved by high performance thin layer chromatography. Ganglioside mixtures as well as separated individual ganglioside fractions were further analyzed by tandem mass spectrometry. Several O-acetylated brain ganglioside species were found in knockout mice, not present in the wild-type mice. To the best of our knowledge this is the first report on the presence of O-acetylated GD1a in St8sia1 null mice and O-acetylated GM3 species in B4galnt1 null mice. In addition, much higher diversity of abnormally accumulated brain ganglioside species regarding the structure of ceramide portion was observed in knockout versus wild-type mice. Obtained findings indicate that the diversity of brain ganglioside structures as well as acetylation patterns in mice with altered ganglioside biosynthesis, is even higher than previously reported. Further investigation is needed in order to explore the effects of acetylation on ganglioside interactions with other molecules and consequently the physiological role of acetylated ganglioside species.

Cholesterogenic genes expression in brain and liver of ganglioside-deficient mice.

The aim of this study was to determine the effect of changed ganglioside profile on transcription of selected genes involved in cholesterol homeostasis. For that purpose, the expression of 11 genes related to cholesterol synthesis, regulation, and cholesterol transport was investigated in selected brain regions (frontal cortex, hippocampus, brain stem, cerebellum) and liver of St8sia1 knockout (KO) mice characterized by deficient synthesis of b- and c-series gangliosides and accumulation of a-series gangliosides. The expression of majority of the analyzed genes, as determined using quantitative real time PCR, was slightly higher in St8sia1 KO compared to wild-type (wt) controls. More prominent changes were observed in Hmgr, Cyp51, and Cyp46 expression in brain (hippocampus and brain stem) and Srebp1a, Insig2a, and Ldlr in liver. In addition, the expression of master transcriptional regulators, Srebp1a, Srebp1c, and Insig2a, as well as transporters Ldlr and Vldlr differed between liver and brain, and within brain regions in wt animals. Cyp46 expression was expectedly brain-specific, with brain region difference in both wt and St8sia1 KO. The established change in transcriptome of cholesterogenic genes is associated to specific alteration of ganglioside composition which indicates relationship between gangliosides and regulation of cholesterol metabolism.

Neuroplastin expression in the hippocampus of mice lacking complex gangliosides.

We report changes in neuroplastin gene and protein expression in the hippocampus of B4galnt1 null mice, which lacks complex ganglioside structures, compared with that of wild-type mice. Neuroplastin mRNA expression was significantly higher in the hippocampi of B4galnt1 null mice than in wild-type mice. Moreover, Western blot analysis shows increased neuroplastin protein levels of neuroplastin-55 isoform in B4galnt1 null hippocampal homogenates. Immunohistochemistry revealed a substantially different distribution of neuroplastin immunoreactivity in sagittal sections of the hippocampi derived from B4galnt1 null in comparison with those from wild-type mice. Most strikingly, B4galnt1 null mice had relatively little neuroplastin immunoreactivity in the pyramidal layer of CA1 and CA3, whereas wild-type mice had strong neuroplastin staining of pyramidal cells. Results of this study support the hypothesis that alterations of brain ganglioside expression influence the expression of neuroplastin. As both neuroplastin and gangliosides have important roles in synaptic transmission, synaptic plasticity, and neurite outgrowth, it will be of particular interest to unravel the molecular mechanisms underlying the relationship between ganglioside composition and neuroplastin transcript and protein expression in the mammalian nervous system.

Arylsulfatase a gene polymorphisms in relapsing remitting multiple sclerosis: genotype-phenotype correlation and estimation of disease progression.

Arylsulfatase A (ASA) is a lysosomal enzyme involved in catabolism of cerebroside-sulfate, major lipid constituent of oligodendrocyte membranes. Various polymorphisms in ASA gene have been described, leading to different levels of enzyme deficiency. Progressive demyelination occurs in metachromatic leukodystrophy (MLD), while the condition of ASA-pseudodeficiency (ASA-PD) is suggested to contribute to complex pathogenesis of multiple sclerosis (MS). This work presents usefulness of genotype-phenotype correlation in estimation of disease severity and progression. The presence of two most common mutations associated with ASA-PD was analyzed in 56 patients with diagnosis of relapsing-remitting multiple sclerosis, by polymerase chain reaction restriction fragment length polymorphism method. In MS patients confirmed as ASA-PD mutations carriers, arylsulfatase activity was determined in leukocyte homogenates by spectrophotometry. To determine whether there is a difference between disability level and/or disease progression in patients with or without mutations we have estimated disability level using Expanded disability status scale (EDSS) and disease progression using Multiple sclerosis severity score (MSSS). Correlation of genotypes and disease progression was statistically analyzed by Kruskal-Wallis test. Patients showing higher MSSS score and found to be carriers of both analyzed ASA-PD mutations were additionally examined using conventional magnetic resonance (MR) techniques. The presence of either one or both mutations was determined in 13 patients. Lower ASA activities were observed in all MS patients carrying the mutations. Nine of the mutations carriers had mild disability (EDSS=0-4.0), 1 had moderate disability (EDSS=4.5-5.5), and 3 had severe disability (EDSS > or = 6.0). On the other hand, only 3 MS patients who were mutation carriers showed MSSS values lower than 5.000 while in other MS patients-mutation carriers the MSSS values ranged from 5.267 to 9.453. Comparison of MR findings between MS patients, mutations carrier vs. non-carrier, matched for sex, age and disease duration, showed that the total number of lesions and the number of hypointense lesions on T1-weighted images was greater in MS patient carrying the ASA-PD mutations. Our results on genotype-phenotype correlation analysis indicate a possible contribution of detected arylsulfatase A gene polymorphisms to the clinical severity of multiple sclerosis, estimated by EDSS, MSSS and MR findings. The MSSS proved to be more appropriate indicator of disease progression and should be more frequently used in clinical practice especially for comparison of disease progression in different groups of patients and identification of factors that may influence disease progression such as the presence of gene polymorphisms.