Swapna V. Shenvi

A nutrient-dense, high-fiber, fruit-based supplement bar increases HDL cholesterol, particularly large HDL, lowers homocysteine, and raises glutathione in a 2-wk trial

Dietary intake modulates disease risk, but little is known how components within food mixtures affect pathophysiology. A low‐calorie, high‐fiber, fruit‐based nutrient‐dense bar of defined composition (e.g., vitamins and minerals, fruit polyphenolics, β‐glucan, docosahexaenoic acid) appropriate for deconstruction and mechanistic studies is described and evaluated in a pilot trial. The bar was developed in collaboration with the U.S. Department of Agriculture. Changes in cardiovascular disease and diabetes risk biomarkers were measured after 2 wk twice‐daily consumption of the bar, and compared against baseline controls in 25 healthy adults. Plasma HDL‐cholesterol (HDL‐c) increased 6.2% (P=0.001), due primarily to a 28% increase in large HDL (HDL‐L; P<0.0001). Total plasma homocysteine (Hcy) decreased 19% (P=0.017), and glutathione (GSH) increased 20% (P=0.011). The changes in HDL and Hcy are in the direction associated with decreased risk of cardiovascular disease and cognitive decline; increased GSH reflects improved antioxidant defense. Changes in biomarkers linked to insulin resistance and inflammation were not observed. A defined food‐based supplement can, within 2 wk, positively impact metabolic biomarkers linked to disease risk. These results lay the groundwork for mechanistic/deconstruction experiments to identify critical bar components and putative synergistic combinations responsible for observed effects.—Mietus‐Snyder, M. L., Shigenaga, M. K., Suh, J. H., Shenvi, S. V., Lal, A., McHugh, T., Olson, D., Lilienstein, J., Krauss, R. M., Gildengoren, G., McCann, J. C., Ames, B. N. A nutrient‐dense, high‐fiber, fruit‐based supplement bar increases HDL cholesterol, particularly large HDL, lowers homocysteine, and raises glutathione in a 2‐wk trial. FASEB J. 26, 3515–3527 (2012). www.fasebj.org

Thiol/redox metabolomic profiling implicates GSH dysregulation in early experimental graft versus host disease (GVHD).

Graft-versus-host disease (GVHD) is a common complication of allogeneic bone marrow transplantation (BMT). Upregulation of inflammatory cytokines precedes the clinical presentation of GVHD and predicts its severity. In this report, thiol/redox metabolomics was used to identify metabolic perturbations associated with early preclinical (Day+4) and clinical (Day+10) stages of GVHD by comparing effects in Syngeneic (Syn; major histocompatibility complex- identical) and allogeneic transplant recipients (Allo BMT) in experimental models. While most metabolic changes were similar in both groups, plasma glutathione (GSH) was significantly decreased, and GSH disulfide (GSSG) was increased after allogeneic compared to syngeneic recipient and non-transplant controls. The early oxidation of the plasma GSH/GSSG redox couple was also observed irrespective of radiation conditioning treatment and was accompanied by significant rise in hepatic protein oxidative damage and ROS generation. Despite a significant rise in oxidative stress, compensatory increase in hepatic GSH synthesis was absent following Allo BMT. Early shifts in hepatic oxidative stress and plasma GSH loss preceded a statistically significant rise in TNF-α. To identify metabolomic biomarkers of hepatic GVHD injury, plasma metabolite concentrations analyzed at Day+10 were correlated with hepatic organ injury. GSSG (oxidized GSH) and β-alanine, were positively correlated, and plasma GSH cysteinylglycine, and branched chain amino acids were inversely correlated with hepatic injury. Although changes in plasma concentrations of cysteine, cystathionine (GSH precursors) and cysteinylglycine (a GSH catabolite) were not significant by univariate analysis, principal component analysis (PCA) indicated that accumulation of these metabolites after Allo BMT contributed significantly to early GVHD in contrast to Syn BMT. In conclusion, thiol/redox metabolomic profiling implicates that early dysregulation of host hepatic GSH metabolism and oxidative stress in sub-clinical GVHD before elevated TNF-α levels is associated with GVHD pathogenesis. Future studies will probe the mechanisms for these changes and examine the potential of antioxidant intervention strategies to modulate GVHD.

A moderate increase in dietary zinc reduces DNA strand breaks in leukocytes and alters plasma proteins without changing plasma zinc concentrations

Background: Food fortification has been recommended to improve a population’s micronutrient status. Biofortification techniques modestly elevate the zinc content of cereals, but few studies have reported a positive impact on functional indicators of zinc status. Objective: We determined the impact of a modest increase in dietary zinc that was similar to that provided by biofortification programs on whole-body and cellular indicators of zinc status. Design: Eighteen men participated in a 6-wk controlled consumption study of a low-zinc, rice-based diet. The diet contained 6 mg Zn/d for 2 wk and was followed by 10 mg Zn/d for 4 wk. To reduce zinc absorption, phytate was added to the diet during the initial period. Indicators of zinc homeostasis, including total absorbed zinc (TAZ), the exchangeable zinc pool (EZP), plasma and cellular zinc concentrations, zinc transporter gene expression, and other metabolic indicators (i.e., DNA damage, inflammation, and oxidative stress), were measured before and after each dietary-zinc period. Results: TAZ increased with increased dietary zinc, but plasma zinc concentrations and EZP size were unchanged. Erythrocyte and leukocyte zinc concentrations and zinc transporter expressions were not altered. However, leukocyte DNA strand breaks decreased with increased dietary zinc, and the level of proteins involved in DNA repair and antioxidant and immune functions were restored after the dietary-zinc increase. Conclusions: A moderate 4-mg/d increase in dietary zinc, similar to that which would be expected from zinc-biofortified crops, improves zinc absorption but does not alter plasma zinc. The repair of DNA strand breaks improves, as do serum protein concentrations that are associated with the DNA repair process. This trial was registered at clinicaltrials.gov as NCT02861352.

A multicomponent nutrient bar promotes weight loss and improves dyslipidemia and insulin resistance in the overweight/obese: chronic inflammation blunts these improvements

This study determined if twice‐daily consumption of a nutrient‐dense bar intended to fill gaps in Western diets, without other dietary/lifestyle requirements, favorably shifted metabolic/anthropometric indicators of dysregulation in a healthy direction. Three 8‐wk clinical trials in 43 healthy lean and overweight/obese (OW/OB) adults, who served as their own controls, were pooled for analysis. In less inflamed OW/OB [high‐sensitivity C‐reactive protein (hsCRP) <1.5], statistically significant decreases occurred in weight (‐1.1 ± 0.5 kg), waist circumference (‐3.1 ± 1.4 cm), diastolic blood pressure (‐4.1 ± 1.6 mmHg), heart rate [HR; ‐4.0 ± 1.7 beats per minute (bpm)], triglycerides (‐72 ± 38.2 mg/dl), insulin resistance (homeostatic model of insulin resistance) (‐0.72 ± 0.3), and insulin (‐2.8 ± 1.3 mU/L); an increase in HDL‐2b (+303 ± 116 nM) and realignment of LDL lipid subfractions toward a less atherogenic profile [decreased small LDL IIIb (‐44 ± 23.5 nM), LDL IIIa (‐99 ± 43.7 nM), and increased large LDLI (+66 ± 28.0 nM)]. In the more inflamed OW/OB (hsCRP >1.5), inflammation was reduced at 2 wk (‐0.66 mg/L), and HR at 8 wk (‐3.4 ± 1.3 bpm). The large HDL subfraction (10.5‐14.5 nm) increased at 8 wk (+346 ± 126 nM). Metabolic improvements were also observed in lean participants. Thus, favorable changes in measures of cardiovascular health, insulin resistance, inflammation, and obesity were initiated within 8 wk in the OW/OB by replacing deficiencies in Western diets without requiring other dietary or lifestyle modifications; chronic inflammation blunted most improvements.—McCann, J. C., Shigenaga, M. K., Mietus‐Snyder, M. L., Lal, A., Suh, J. H., Krauss, R. M., Gildengorin, G. L., Goldrich, A. M., Block, D. S., Shenvi, S. V., McHugh, T. H., Olson, D. A., Ames, B. N. A multicomponent nutrient bar promotes weight loss and improves dyslipidemia and insulin resistance in the overweight/obese: chronic inflammation blunts these improvements. FASEB J. 29, 3287‐3301 (2015). www.fasebj.org

Identification of age-specific Nrf2 binding to a novel ARE locus in the Gclc promoter: a compensatory means for the loss of glutathione synthetic capacity in the aging rat liver?

NFE2‐related factor 2 (Nrf2) transcriptionally governs the cellular response to harmful electrophiles, xenobiotics, and reactive oxygen species. Its nuclear levels decline with age ( Suh et al., 2004a ), which in part explains the age‐related loss of phase II detoxification. However, little work has yet characterized how age affects Nrf2 DNA binding or the role that alterations to the Nrf2 transcriptional apparatus plays in modulating Nrf2‐mediated gene expression. In this study, we used immunoprecipitation assays to show that Nrf2 bound to the active antioxidant response element (ARE) of the catalytic subunit of glutamate cysteine ligase (GCLC) is significantly lower in hepatic chromatin from aged vs. young rats. Moreover, the activity at this ARE locus is diminished during aging because of the presence of Bach1 and the absence of CREB‐binding protein (CBP), a transcriptional repressor and co‐activator, respectively. Further analysis reveals that Nrf2 occupies an alternate ARE site located −2.2 kb downstream from the normally active ARE binding site in livers of old rats, indicating an age‐specific adaptation to maintain gene expression. Our results, thus, show that the conversion of Nrf2 binding from an active ARE to an alternative ARE element is not adequate to maintain basal expression of hepatic Gclc in old rats, which provides a potential mechanism for the age‐related loss of glutathione synthetic and other phase II enzymes.

Identification of age-specific Nrf2 binding to a novel antioxidant response element locus in the Gclc promoter: a compensatory means for the loss of glutathione synthetic capacity in the aging rat liver?: Glutathione synthesis in aging

NFE2‐related factor 2 (Nrf2) transcriptionally governs the cellular response to harmful electrophiles, xenobiotics, and reactive oxygen species. Its nuclear levels decline with age ( Suh et al., 2004a ), which in part explains the age‐related loss of phase II detoxification. However, little work has yet characterized how age affects Nrf2 DNA binding or the role that alterations to the Nrf2 transcriptional apparatus plays in modulating Nrf2‐mediated gene expression. In this study, we used immunoprecipitation assays to show that Nrf2 bound to the active antioxidant response element (ARE) of the catalytic subunit of glutamate cysteine ligase (GCLC) is significantly lower in hepatic chromatin from aged vs. young rats. Moreover, the activity at this ARE locus is diminished during aging because of the presence of Bach1 and the absence of CREB‐binding protein (CBP), a transcriptional repressor and co‐activator, respectively. Further analysis reveals that Nrf2 occupies an alternate ARE site located −2.2 kb downstream from the normally active ARE binding site in livers of old rats, indicating an age‐specific adaptation to maintain gene expression. Our results, thus, show that the conversion of Nrf2 binding from an active ARE to an alternative ARE element is not adequate to maintain basal expression of hepatic Gclc in old rats, which provides a potential mechanism for the age‐related loss of glutathione synthetic and other phase II enzymes.