A metabolomic signature of decelerated physiological aging in human plasma

The degenerative processes that occur during aging increase the risk of disease and impaired health. Meanwhile, interventions that target aging to promote healthy longevity are gaining interest, both academically and in the public. While nutritional and physical interventions exist, efficacy is often difficult to determine. It is therefore imperative that an aging score measuring the biological aging process is available to the wider public. However, simple, interpret, and accessible biological aging scores are lacking. Here, we developed PhysiAge, a physiological aging score based on five accessible parameters that have influence on or reflect the aging process: (1) average daily step count, (2) blood glucose, (3) systolic blood pressure, (4) sex, and (5) age. Here, we found that compared to calendar age alone, PhysiAge better predicts mortality, as well as established muscle aging markers such as decrease in NAD+ levels, increase in oxidative stress, and decline in physical functioning. In order to demonstrate the usefulness of PhysiAge in identifying relevant factors associated with decelerated aging, we calculated PhysiAges for a cohort of aged individuals and obtained mass spectrometry-based blood plasma metabolomic profiles for each individual. Here, we identified a metabolic signature of decelerated aging, which included components of the TCA cycle, including malate, citrate, and isocitrate. Higher abundance of these metabolites was associated with decelerated aging, in line with supplementation studies in model organisms. PhysiAge represents an accessible way for people to track and intervene in their aging trajectories, and identifies a metabolic signature of decelerated aging in human blood plasma, which can be further studied for its causal involvement in human aging.

Fluorometric determination of isocitrate dehydrogenase (EC 1.1.1.42; 1; NADP+ dependent) in ruminant milk

The enzyme isocitrate dehydrogenase (EC 1.1.1.42; 1; NADP⁺ dependent) located in the mammary cell cytosol mediates the synthesis of the majority of reducing equivalents for the energetically demanding milk fat and cholesterol synthesis in mammary cell cytosol. The present article presents a novel fluorometric method for quantification of the activity of this enzyme (IDH) in ruminant milk without pretreatment of the sample. Further, 493 goat milk samples - harvested before, during and after a nutritional restriction - were analysed for IDH activity i) with addition of extra substrate (isocitrate), and ii) with the intrinsic isocitrate solely. The IDH activity ranged from 0.22 to 15.4 units [nano moles product/(ml * min)] (un-supplemented) and from 0.22 to 45.6 units (isocitrate supplemented). The IDH activity increased considerably in milk during the nutritional restriction period concomitant with the increase in the metabolite isocitrate concentration and somatic cell count and returned to the initial level shortly after restriction period. The present 'high through-put' analytical method may be beneficial in future studies to phenotype modifications in mammary energy metabolism and milk fat synthesis, for which IDH activity may be a biomarker.

Isocitrate Dehydrogenase Mutations Are Associated with Different Expression and DNA Methylation Patterns of OLIG2 in Adult Gliomas

Isocitrate dehydrogenase (IDH) mutant gliomas are associated with a better prognosis in comparison to adult IDH wild-type glioma and glioma-CpG island methylator phenotypes. Although OLIG2 is mainly expressed in oligodendrocytes in normal adult brain, it is expressed in both astrocytomas and oligodendrogliomas. Utilizing the clinical, DNA methylation, and RNA-sequencing data from the Cancer Genome Atlas (TCGA) for lower-grade glioma and glioblastoma cohorts, we explored the association between IDH mutation status and OLIG2 expression on transcription, DNA methylation, and gene target levels. Compared to IDH wild-type gliomas, IDH mutant gliomas showed consistently higher expression of OLIG2 transcripts. OLIG2 overexpression is a good surrogate marker for IDH mutation with an AUC of 0.90. At the DNA methylation level, IDH-mutant gliomas showed hyper- and hypomethylation foci upstream of the OLIG2 transcription start site. Underexpressed OLIG2 target genes in IDH mutant glioma were enriched in cell cycle-related pathways. Thus, the differential expression of OLIG2 between IDH mutant and wild-type gliomas reflects involvement in multiple pathways in tumorigenesis.

Hydroxycarboxylate combinations for increasing solubility and robustness of supersaturated solutions of whey mineral residues

Calcium phosphates present in whey mineral residue is a potential source of calcium for dietary purposes. Combinations of aqueous isocitrate and citrate were found more efficient than each of the isomers in dissolving dried insoluble whey processing mineral residues spontaneously forming supersaturated solutions. Hydrogen isocitrate was found around 30% less efficient in these non thermal dissolution processes compared to hydrogen citrate based on amount of dissolved calcium. In contrast, the lag phase of up to 4 h for precipitation of calcium citrate from the supersaturated solutions was significantly longer when calcium isocitrate was present. Highest degree of supersaturation with longest lag phase for precipitation was found for citrate/isocitrate combinations in a 1:1 ratio. Addition of calcium saccharate during dissolution further prolonged the lag phase simultaneously preserving the higher supersaturation degrees. Combinations of the three hydroxycarboxylates seem accordingly to provide a basis for increasing calcium availability from dried whey mineral fractions consisting mainly of calcium hydrogen phosphate and hydroxyapatite of low solubility with the perspective of transforming a side stream from cheese production into valuable functional foods.

Dataset on the organic acids, sulphate, total nitrogen and total chlorophyll contents of two lettuce cultivars grown hydroponically using nutrient solutions of variable macrocation ratios

The data presented in this article were derived from dry and fresh samples of soilless-grown butterhead lettuce (Lactuca sativa L. var. Capitata). Organic acids, total nitrogen, sulphate and total chlorophyll concentrations varied in response to cultivar (red or green butterhead Salanova) and to nutrient solution macrocation ratios (high proportion of K, Ca or Mg). Kjeldahl, spectrophotometry and ion chromatography were the principal employed methods. Data of total nitrogen and sulphate concentrations contribute to the understanding of macrocation uptake by plants and may drive prospective relevant research. Organic acids are indicators of plant tolerance to stress, including nutrient deficiencies, and the variability of their concentrations provide insights to plant stress physiology. The data reported in this paper are related to the research article "The bioactive profile of lettuce produced in a closed soilless system as configured by combinatorial effects of genotype and macrocation supply composition", authored by El-Nakhel et al. (2020) [1].

Isocitrate treatment of acute anemia of inflammation in a mouse model

Acute and severe anemia of inflammation (AI) is a common complication of various clinical syndromes, including fulminant infections, critical illness with multiorgan failure, and exacerbations of autoimmune diseases. Building on recent data showing beneficial results with isocitrate treatment for chronic low-grade AI in a rat model, we used a mouse model of acute and severe AI induced by intraperitoneal heat-killed Brucella abortus to determine if isocitrate would be effective in this more stringent application. Inflamed mice treated with isocitrate developed an early but transient improvement in hemoglobin compared to solvent-treated controls, with a robust improvement on day 7, and only a trend towards improvement by day 14. Reticulocyte counts were increased in treated mice transiently, with no significant difference by day 21. Serum erythropoietin (EPO) levels were similar in treated versus control mice, indicating that isocitrate increased sensitivity to EPO. Serum and tissue iron levels showed no significant differences between the treated and control mice, ruling out improved iron availability as the cause of the increased response to endogenous EPO. Compared to the milder rat model, much higher doses of isocitrate were required for a relatively modest benefit.

Identification of a new selective chemical inhibitor of mutant isocitrate dehydrogenase-1

Background:

Recent genome-wide sequencing studies have identified unexpected genetic alterations in cancer. In particular, missense mutations in isocitrate dehydrogenase-1 (IDH1) at arginine 132, mostly substituted into histidine (IDH1-R132H) were observed to frequently occur in glioma patients.

Methods:

We have purified recombinant IDH1 and IDH1-R132H proteins and monitored their catalytic activities. In parallel experiments, we have attempted to find new selective IDH1-R132H chemical inhibitor(s) from a fragment-based chemical library.

Results:

We have found that IDH1, but not IDH1-R132H, can catalyze the conversion of isocitrate into α-ketoglutarate (α-KG). In addition, we have observed that IDH1-R132H was more efficient than IDH1 in converting α-KG into (R)-2-hydroxyglutarate (R-2HG). Moreover, we have identified a new hit molecule, e.g., 2-(3-trifluoromethylphenyl)isothioazol-3(2H)-one as a new selective IDH1-R132H inhibitor.

Conclusions:

We have observed an underlying biochemical mechanism explaining how a heterozygous IDH1 mutation contributes to the generation of R-2HG and increases cellular histone H3 trimethylation levels. We have also identified a novel selective IDH1-R132H chemical hit molecule, e.g., 2-(3-trifluoromethylphenyl)isothioazol-3(2H)-one, which could be used for a future lead development against IDH1-R132H.