Brain cholesterol homeostasis in Wilson disease

High levels of 27-hydroxycholesterol results in synaptic plasticity alterations in the hippocampus

Alterations in brain cholesterol homeostasis in midlife are correlated with a higher risk of developing Alzheimer’s disease (AD). However, global cholesterol-lowering therapies have yielded mixed results when it comes to slowing down or preventing cognitive decline in AD. We used the transgenic mouse model Cyp27Tg, with systemically high levels of 27-hydroxycholesterol (27-OH) to examine long-term potentiation (LTP) in the hippocampal CA1 region, combined with dendritic spine reconstruction of CA1 pyramidal neurons to detect morphological and functional synaptic alterations induced by 27-OH high levels. Our results show that elevated 27-OH levels lead to enhanced LTP in the Schaffer collateral-CA1 synapses. This increase is correlated with abnormally large dendritic spines in the stratum radiatum. Using immunohistochemistry for synaptopodin (actin-binding protein involved in the recruitment of the spine apparatus), we found a significantly higher density of synaptopodin-positive puncta in CA1 in Cyp27Tg mice. We hypothesize that high 27-OH levels alter synaptic potentiation and could lead to dysfunction of fine-tuned processing of information in hippocampal circuits resulting in cognitive impairment. We suggest that these alterations could be detrimental for synaptic function and cognition later in life, representing a potential mechanism by which hypercholesterolemia could lead to alterations in memory function in neurodegenerative diseases.

Metabolic Profiling in Formalin-Fixed and Paraffin-Embedded Prostate Cancer Tissues

Metabolite profiling has significantly contributed to a deeper understanding of the biochemical metabolic networks and pathways in cancer cells. Metabolomics-based biomarker discovery would greatly benefit from the ability to interrogate retrospective annotated clinical specimens archived as formalin-fixed, paraffin-embedded (FFPE) material. Mass spectrometry-based metabolomic analysis was performed in matched frozen and FFPE human prostate cancers as well as isogenic prostate cancer cell lines. A total of 352 and 460 metabolites were profiled in human tissues and cell lines, respectively. Classes and physical-chemical characteristics of the metabolites preserved in FFPE material were characterized and related to their preservation or loss following fixation and embedding. Metabolite classes were differentially preserved in archival FFPE tissues, regardless of the age of the block, compared with matched frozen specimen, ranging from maximal preservation of fatty acids (78%) to loss of the majority of peptides and steroids. Generally, FFPE samples showed a decrease of metabolites with functional groups, such as carboxamide. As an adjunct technique, metabolic profiles were also obtained in situ from FFPE tissue sections where metabolites were extracted in a manner that preserves tissue architecture. Despite the fact that selected metabolites were not retained after processing, global metabolic profiles obtained from FFPE can be used to predict biologic states and study biologic pathways. These results pave the way for metabolomics-based biomarker discovery/validation utilizing retrospective and clinically annotated FFPE collections.Implications: Metabolic profiles can be performed in archival tissue and may be used to complement other profiling methods such as gene expression for biomarker discovery or pathway analysis in the assessment of biologic states. Mol Cancer Res; 15(4); 439-47. ©2017 AACR.

Neurological features and management of Wilson disease in children: an evaluation of 12 cases

AIM

Wilson's disease is an autosomal recessive disorder of copper metabolism which leads to copper overload in different tissues of the body. The aim of this study was to present the neurologic features of Wilson's disease and to assess the clinical course of neurological findings in children receiving anti-copper treatment.

MATERIAL AND METHODS

Twelve children with a diagnosis of Wilson's disease and findings of central nervous system involvement who were followed up in the Department of Pediatric Neurology and Pediatric Gastroenterology of the School of Medicine at Erciyes University were enrolled in the study.

RESULTS

The study cases consisted of five boys (42%) and seven girls (58%). The mean age at the time of diagnosis was 9.9±3.4 years (5-15 years). The mean duration of follow-up was 49.0±36.4 months (15-128 months). Neurological findings at presentation included headache in seven cases (58%), tremor in seven cases (58%), dystonia in three cases (25%), ataxia in two cases (17%), dizziness in two cases (17%), numbness in the hands and acute weakness in one case (8%) and syncope in one case (8%). Headache, dizziness, syncope, numbness in hands and acute weakness symptoms resolved completely within six months after receiving treatment. Movement disorders either decreased or remained stable in seven of the eight cases. However, one patient developed progressively worsening dystonia despite to all treatments.

CONCLUSIONS

Wilson's disease can be manifested with signs and symptoms of central nervous system in the childhood. Wilson's disease should be considered in all children presenting with movement disorders. A complete neurological assessment should be carried out in all cases with Wilson's disease.

Identification of metabolic markers in coronary artery disease using an untargeted LC-MS based metabolomic approach

Coronary artery disease (CAD), a complex metabolic disorder, is one of the largest causes of death worldwide. Both environmental and genetic factors contribute to the etiology of this metabolic disease. The gene-environment interaction could lead to modulation of various metabolic pathways resulting in altered levels of various metabolites. Thus, identifying metabolites could aid in deciphering pathways that could be involved in the pathophysiology of the disease. With the advent of high resolution mass spectrometry based methodologies, it is now possible to screen thousands of metabolites in a single snapshot thus, allowing the identification of potential disease metabolite markers. In this work, using an untargeted metabolomic approach, we attempted to identify metabolites that have altered levels in CAD patients. Using reverse phase and HILIC based chromatography followed by mass spectrometry we identified a total of 32 metabolites (2 fold; p<0.05) in plasma whose levels were significantly altered in CAD samples. Further, we have validated the discriminative ability of these metabolites in an independent set of CAD and control samples using multivariate PLS-DA analysis. Interestingly, Lyso PC (18:0), Cortisol, Lyso PC (P-17:0), and glycerophosphocholine were among the top discriminators for CAD which implies involvement of phosphatidylcholine pathway in the pathogenesis of atherosclerosis.

BIOLOGICAL SIGNIFICANCE

Herein, we report that an unbiased metabolomic study has the potential to identify newer markers which are involved in several important biological pathways like lipid metabolism, phosphatidylcholine pathway etc. which in turn are implicated in CAD. These markers could be of potential clinical importance for screening subjects at risk of CAD. This article is part of a Special Issue entitled: Proteomics in India.

Modifying factors and phenotypic diversity in Wilson's disease

Wilson's disease (WD) is a human disorder of copper homeostasis caused by mutations in the copper-transporting ATPase ATP7B. WD is characterized by copper accumulation, predominantly in the liver and brain, hepatic pathology, and wide differences between patients in the age of onset and the spectrum of symptoms. Several factors contribute to the phenotypic variability of WD. The WD-causing mutations produce a wide range of changes in stability, activity, intracellular localization, and trafficking of ATP7B; the nonpathogenic genetic polymorphisms may contribute to the phenotype. In Atp7b(-/-) mice, a mouse model of WD, an abnormal intracellular distribution of copper in the liver triggers distinct changes in the transcriptome; these mRNA profiles might be used to more specifically define disease progression. The major effect of accumulating copper on lipid metabolism and especially cholesterol homeostasis in mice and humans suggests the importance of fat and cholesterol metabolism as modifying factors in WD.