Molecular effects of isoflavone supplementation : human intervention studies and quantitative models for risk assessment

Background: Risk assessment can potentially be improved by closely linked experiments in the disciplines of epidemiology and toxicology. This was explored for isoflavones in a case study. For isoflavones potential beneficial health effects have been suggested, but discussions on their safety are ongoing as well. Aims and methods: Effects of isoflavone supplements on gene expression were studied in white blood cells (PBMCs) and adipose tissue, among postmenopausal women in two human intervention studies. To advance risk assessment, the dose response relation between intake and blood levels was studied with a log-linear regression model as well as the comparability of the human gene expression profiles with results from a rat experiment using multivariate analysis. Results: In both PBMCs and adipose tissue, changes in gene expression profiles pointed at effects of isoflavones on energy metabolism, inflammation and cell cycle; these effects were modified by supplement composition and equol-producing phenotype. Hypothesized estrogen-responsive effects were not observed. For the intake range of 0-100mg/day, the plasma concentrations of daidzein, equol, genistein and total isoflavones were quantified, interindividual variation. Expression of estrogen-responsive gene profiles and other biological pathways could be quantitatively compared between PBMCs and adipose tissue, as well as between humans and rats. en nog iets Conclusion: Effects of isoflavone supplementation on gene expression in PBMCs and adipose tissue of postmenopausal women suggest mainly beneficial effects of a dose of ~100mg/day. The absence of a clear estrogen-like response suggested a limited role of the estrogen receptor in isoflavone induced gene expression in postmenopausal women. The trials and quantitative models provide important tools[AG1] that enable further exploration of intertissue and interspecies comparability and advancing the use of transcriptomics in assessing risks and benefits. Modelling data from human and animal studies provide important possibilities for further exploration of intertissue and interspecies similarities and for the use of transcriptomics in improving risk assessment. </p

Single-Step Extraction Coupled with Targeted HILIC-MS/MS Approach for Comprehensive Analysis of Human Plasma Lipidome and Polar Metabolome.

Expanding metabolome coverage to include complex lipids and polar metabolites is essential in the generation of well-founded hypotheses in biological assays. Traditionally, lipid extraction is performed by liquid-liquid extraction using either methyl-tert-butyl ether (MTBE) or chloroform, and polar metabolite extraction using methanol. Here, we evaluated the performance of single-step sample preparation methods for simultaneous extraction of the complex lipidome and polar metabolome from human plasma. The method performance was evaluated using high-coverage Hydrophilic Interaction Liquid Chromatography-ESI coupled to tandem mass spectrometry (HILIC-ESI-MS/MS) methodology targeting a panel of 1159 lipids and 374 polar metabolites. The criteria used for method evaluation comprised protein precipitation efficiency, and relative MS signal abundance and repeatability of detectable lipid and polar metabolites in human plasma. Among the tested methods, the isopropanol (IPA) and 1-butanol:methanol (BUME) mixtures were selected as the best compromises for the simultaneous extraction of complex lipids and polar metabolites, allowing for the detection of 584 lipid species and 116 polar metabolites. The extraction with IPA showed the greatest reproducibility with the highest number of lipid species detected with the coefficient of variation (CV) &lt; 30%. Besides this difference, both IPA and BUME allowed for the high-throughput extraction and reproducible measurement of a large panel of complex lipids and polar metabolites, thus warranting their application in large-scale human population studies

Sex-specific alterations in NAD+ metabolism in 3xTg Alzheimer's disease mouse brain assessed by quantitative targeted LC-MS.

Levels of nicotinamide adenine dinucleotide (NAD+) are known to decline with age and have been associated with impaired mitochondrial function leading to neurodegeneration, a key facet of Alzheimer's disease (AD). NAD+synthesis is sustained via tryptophan-kynurenine (Trp-Kyn) pathway as de novo synthesis route, and salvage pathways dependent on the availability of nicotinic acid and nicotinamide. While being currently investigated as a multifactorial disease with a strong metabolic component, AD remains without curative treatment and important sex differences were reported in relation to disease onset and progression. The aim of this study was to reveal the potential deregulation of NAD+metabolism in AD with the direct analysis of NAD+precursors in the mouse brain tissue (wild type (WT) versus triple transgenic (3xTg) AD), using a sex-balanced design. To this end, we developed a quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, which allowed for the measurement of the full spectrum of NAD+precursors and intermediates in all three pathways. In brain tissue of mice with developed AD symptoms, a decrease in kynurenine (Kyn) versus increase in kynurenic acid (KA) levels were observed in both sexes with a significantly higher increment of KA in males. These alterations in Trp-Kyn pathway might be a consequence of neuroinflammation and a compensatory production of neuroprotective kynurenic acid. In the NAD+ salvage pathway, significantly lower levels of nicotinamide mononucleotide (NMN) were measured in the AD brain of males and females. Depletion of NMN implies the deregulation of salvage pathway critical for maintaining optimal NAD+ levels and mitochondrial and neuronal function

LC-HRMS data as a result of untargeted metabolomic profiling of human cerebrospinal fluid.

Cerebrospinal fluid (CSF) is a key body fluid that maintains the homeostasis in central nervous system (CNS). As a biofluid whose content reflects the brain metabolic activity, the CSF is analyzed in the context of neurological diseases and is rarely collected from healthy subjects. For this reason, the metabolite variation associated with general phenotypic characteristics such as gender and age have hardly ever been studied. Here we present the hydrophilic interaction liquid chromatography-high resolution mass spectrometry (HILIC-HRMS) data as a result of untargeted metabolomics analysis of a cohort of elderly cognitively healthy volunteers ( &lt;i&gt;n&lt;/i&gt;  = 32). 146 unambiguously identified water soluble metabolites (using accurate mass, retention time and MS/MS matching against spectral libraries) were measured and their abundances across all the subjects depending on their gender are provided in this article. Data tables are available at https://data.mendeley.com/datasets/c73xtsd4s5/1. it's published on mendeley, the DOI is DOI:10.17632/c73xtsd4s5.1. The data presented in this article are related to the research article entitled "A global HILIC-MS approach to measure polar human cerebrospinal fluid metabolome: Exploring gender-associated variation in a cohort of elderly cognitively healthy subjects" (Gallart-Ayala et al., 2018, In press)

Merged Targeted Quantification and Untargeted Profiling for Comprehensive Assessment of Acylcarnitine and Amino Acid Metabolism.

Acylcarnitines and amino acids are key players in energy metabolism; however, analytical methods for comprehensive and straightforward quantitative profiling of these metabolites, without derivatization or use of ion-pairing agents, are lacking. We therefore developed a hydrophilic interaction chromatography (HILIC)-based high-resolution mass spectrometry (HRMS) method for the simultaneous quantification of acylcarnitines and amino acids in a single run, while taking advantage of HRMS data acquired in full-scan mode to screen for additional derivatives and other polar metabolites. A single-step metabolite extraction with internal standard mixture (in methanol) warranted high-throughput sample preparation whose applicability was demonstrated on a panel of human biofluids (i.e., blood plasma, CSF, and urine) and brain tissue. Method accuracy was within 90-106% of validated NIST reference plasma concentrations for the panel of measured amino acids. Amino acid and acylcarnitine extraction recoveries were 87-100% on average, depending on the concentration range spiked. The coefficient of variation (CV) was 1-10% and 1-25% for intra- and interday measurements, respectively, with the highest CVs for the metabolites at the limit of quantification, depending on the biofluid. Acylcarnitine and amino acid signatures or chemical composition barcodes of the different biofluids and human brain tissue were acquired and biofluid- and tissue-associated differences were discussed in the context of their respective physiological roles. Significant differences were observed in the amino acid profiles, whereas acylcarnitine composition did not show biofluid-characteristic or brain region-specific pattern. The retrospective exploration of full-scan all-ion-fragmentation data allowed us to extract the information on unsaturated and hydroxylated acylcarnitine species, amines, and purine and pyrimidine metabolites. This merged targeted and untargeted approach provides an innovative strategy for simultaneous and comprehensive assessment of acylcarnitine and amino acid metabolism in clinical research studies using relevant biofluids and tissue extracts

Systemic and central nervous system metabolic alterations in Alzheimer’s disease

Metabolic alterations, related to cerebral glucose metabolism, brain insulin resistance, and age-induced mitochondrial dysfunction, play an important role in Alzheimer's disease (AD) on both the systemic and central nervous system level. To study the extent and significance of these alterations in AD, quantitative metabolomics was applied to plasma and cerebrospinal fluid (CSF) from clinically well-characterized AD patients and cognitively healthy control subjects. The observed metabolic alterations were associated with core pathological processes of AD to investigate their relation with amyloid pathology and tau-related neurodegeneration. In a case-control study of clinical and biomarker-confirmed AD patients (n = 40) and cognitively healthy controls without cerebral AD pathology (n = 34) with paired plasma and CSF samples, we performed metabolic profiling, i.e., untargeted metabolomics and targeted quantification. Targeted quantification focused on identified deregulated pathways highlighted in the untargeted assay, i.e. the TCA cycle, and its anaplerotic pathways, as well as the neuroactive tryptophan and kynurenine pathway. Concentrations of several TCA cycle and beta-oxidation intermediates were higher in plasma of AD patients, whilst amino acid concentrations were significantly lower. Similar alterations in these energy metabolism intermediates were observed in CSF, together with higher concentrations of creatinine, which were strongly correlated with blood-brain barrier permeability. Alterations of several amino acids were associated with CSF Amyloidβ1-42. The tryptophan catabolites, kynurenic acid and quinolinic acid, showed significantly higher concentrations in CSF of AD patients, which, together with other tryptophan pathway intermediates, were correlated with either CSF Amyloidβ1-42, or tau and phosphorylated Tau-181. This study revealed AD-associated systemic dysregulation of nutrient sensing and oxidation and CNS-specific alterations in the neuroactive tryptophan pathway and (phospho)creatine degradation. The specific association of amino acids and tryptophan catabolites with AD CSF biomarkers suggests a close relationship with core AD pathology. Our findings warrant validation in independent, larger cohort studies as well as further investigation of factors such as gender and APOE genotype, as well as of other groups, such as preclinical AD, to identify metabolic alterations as potential intervention targets

Subcortical brain structures and the risk of dementia in the Rotterdam Study

Introduction: Volumetric and morphological changes in subcortical brain structures are present in persons with dementia, but it is unknown if these changes occur prior to diagnosis. Methods: Between 2005 and 2016, 5522 Rotterdam Study participants (mean age: 64.4) underwent cerebral magnetic resonance imaging (MRI) and were followed for development of dementia until 2018. Volume and shape measures were obtained for seven subcortical structures. Results: During 12 years of follow-up, 272 dementia cases occurred. Mean volumes of thalamus (hazard ratio [HR] per standard deviation [SD] decrease 1.94, 95% confidence interval [CI]: 1.55–2.43), amygdala (HR 1.66, 95% CI: 1.44–1.92), and hippocampus (HR 1.64, 95% CI: 1.43–1.88) were strongly associated with dementia risk. Associations for accumbens, pallidum, and caudate volumes were less pronounced. Shape analyses identified regional surface changes in the amygdala, limbic thalamus, and caudate. Discussion: Structure of the amygdala, thalamus, hippocampus, and caudate is associated with risk of dementia in a large population-based cohort of older adults

Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment

Isoflavones are present in soy foods and soy-based supplements. Despite low plasma isoflavone concentrations in the general Western population, concentrations in supplement users exceed those suggested to be beneficial for health in Asian populations, raising concerns for adverse effects. To aid risk assessment, quantification of the relation between isoflavone intake and plasma concentrations is essential