Correction: The SIRT1 Deacetylase Suppresses Intestinal Tumorigenesis and Colon Cancer Growth.

[This corrects the article DOI: 10.1371/journal.pone.0002020.].

Elevated homocysteine is associated with increased rates of epigenetic aging in a population with mild cognitive impairment.

Elevated plasma total homocysteine (tHcy) is associated with the development of Alzheimer's disease and other forms of dementia. In this study, we report the relationship between tHcy and epigenetic age in older adults with mild cognitive impairment from the VITACOG study. Epigenetic age and rate of aging (ROA) were assessed using various epigenetic clocks, including those developed by Horvath and Hannum, DNAmPhenoAge, and with a focus on Index, a new principal component-based epigenetic clock that, like DNAmPhenoAge, is trained to predict an individual's "PhenoAge." We identified significant associations between tHcy levels and ROA, suggesting that hyperhomocysteinemic individuals were aging at a faster rate. Moreover, Index revealed a normalization of accelerated epigenetic aging in these individuals following treatment with tHcy-lowering B-vitamins. Our results indicate that elevated tHcy is a risk factor for accelerated epigenetic aging, and this can be ameliorated with B-vitamins. These findings have broad relevance for the sizable proportion of the worldwide population with elevated tHcy.

Human trials exploring anti-aging medicines.

Here, we summarize the current knowledge on eight promising drugs and natural compounds that have been tested in the clinic: metformin, NAD+ precursors, glucagon-like peptide-1 receptor agonists, TORC1 inhibitors, spermidine, senolytics, probiotics, and anti-inflammatories. Multiple clinical trials have commenced to evaluate the efficacy of such agents against age-associated diseases including diabetes, cardiovascular disease, cancer, and neurodegenerative diseases. There are reasonable expectations that drugs able to decelerate or reverse aging processes will also exert broad disease-preventing or -attenuating effects. Hence, the outcome of past, ongoing, and future disease-specific trials may pave the way to the development of new anti-aging medicines. Drugs approved for specific disease indications may subsequently be repurposed for the treatment of organism-wide aging consequences.

Nicotinamide riboside and pterostilbene reduces markers of hepatic inflammation in NAFLD: A double-blind, placebo-controlled clinical trial.

BACKGROUND AND AIMS: The prevalence of NAFLD is increasing globally and on a path to becoming the most frequent cause of chronic liver disease. Strategies for the prevention and treatment of NAFLD are urgently needed. APPROACH AND RESULTS: A 6-month prospective, randomized, double-blind, placebo-controlled clinical trial was conducted to assess the efficacy of daily NRPT (commercially known as Basis, a combination of nicotinamide riboside and pterostilbene) supplementation in 111 adults with NAFLD. The study consisted of three arms: placebo, recommended daily dose of NRPT (NRPT 1×), and a double dose of NRPT (NRPT 2×). NRPT appeared safe and well tolerated. At the end of the study, no significant change was seen in the primary endpoint of hepatic fat fraction with respect to placebo. However, among prespecified secondary outcomes, a time-dependent decrease in the circulating levels of the liver enzymes alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) was observed in the NRPT 1× group, and this decrease was significant with respect to placebo. Furthermore, a significant decrease in the circulating levels of the toxic lipid ceramide 14:0 was also observed in the NRPT 1× group versus placebo, and this decrease was associated with a decrease in ALT in individuals of this group. A dose-dependent effect was not observed with respect to ALT, GGT, or ceramide 14:0 in the NRPT 2× group. CONCLUSIONS: This study demonstrates that NRPT at the recommended dose is safe and may hold promise in lowering markers of hepatic inflammation in patients with NAFLD.

4-Phenylbutyrate restores localization and membrane repair to human dysferlin mutations.

Dysferlinopathies are muscular dystrophies caused by recessive loss-of-function mutations in dysferlin (DYSF), a membrane protein involved in skeletal muscle membrane repair. We describe a cell-based assay in which human DYSF proteins bearing missense mutations are quantitatively assayed for membrane localization by flow cytometry and identified 64 localization-defective DYSF mutations. Using this platform, we show that the clinically approved drug 4-phenylbutryric acid (4-PBA) partially restores membrane localization to 25 mutations, as well as membrane repair to cultured myotubes expressing 2 different mutations. Two-day oral administration of 4-PBA to mice homozygous for one of these mutations restored myofiber membrane repair. 4-PBA may hold therapeutic potential for treating a subset of humans with muscular dystrophy due to dysferlin deficiency.

Correction: SIRT2 Ablation Has No Effect on Tubulin Acetylation in Brain, Cholesterol Biosynthesis or the Progression of Huntington's Disease Phenotypes In Vivo.

[This corrects the article DOI: 10.1371/journal.pone.0034805.].

Nicotinamide riboside with pterostilbene (NRPT) increases NAD+ in patients with acute kidney injury (AKI): a randomized, double-blind, placebo-controlled, stepwise safety study of escalating doses of NRPT in patients with AKI.

BACKGROUND: Preclinical studies have identified both NAD+ and sirtuin augmentation as potential strategies for the prevention and treatment of AKI. Nicotinamide riboside (NR) is a NAD+ precursor vitamin and pterostilbene (PT) is potent sirtuin activator found in blueberries. Here, we tested the effect of combined NR and PT (NRPT) on whole blood NAD+ levels and safety parameters in patients with AKI. METHODS: We conducted a randomized, double-blind, placebo-controlled study of escalating doses of NRPT in 24 hospitalized patients with AKI. The study was comprised of four Steps during which NRPT (5 subjects) or placebo (1 subject) was given twice a day for 2 days. NRPT dosing was increased in each Step: Step 1250/50 mg, Step 2500/100 mg, Step 3750/150 mg and Step 41,000/200 mg. Blood NAD+ levels were measured by liquid chromatography-mass spectrometry and safety was assessed by history, physical exam, and clinical laboratory testing. RESULTS: AKI resulted in a 50% reduction in whole blood NAD+ levels at 48 h compared to 0 h in patients receiving placebo (p = 0.05). There was a trend for increase in NAD+ levels in all NRPT Steps individually at 48 h compared to 0 h, but only the change in Step 2 reached statistical significance (47%, p = 0.04), and there was considerable interindividual variability in the NAD+ response to treatment. Considering all Steps together, NRPT treatment increased NAD+ levels by 37% at 48 h compared to 0 h (p = 0.002). All safety laboratory tests were unchanged by NRPT treatment, including creatinine, estimated glomerular filtration rate (eGFR), electrolytes, liver function tests, and blood counts. Three of 20 patients receiving NRPT reported minor gastrointestinal side effects. CONCLUSION: NRPT increases whole blood NAD+ levels in hospitalized patients with AKI. In addition, NRPT up to a dose of 1000 mg/200 mg twice a day for 2 days is safe and well tolerated in these patients. Further studies to assess the potential therapeutic benefit of NRPT in AKI are warranted. TRIAL REGISTRATION: NCT03176628 , date of registration June 5th, 2017.

Safety Assessment of High-Purity, Synthetic Nicotinamide Riboside (NR-E) in a 90-Day Repeated Dose Oral Toxicity Study, With a 28-Day Recovery Arm.

Nicotinamide riboside (NR) is a naturally occurring form of vitamin B3 shown to preferentially elevate the nicotinamide adenine dinucleotide (NAD+) metabolome compared to other vitamin B3 forms (nicotinic acid and nicotinamide). Although daily requirements of vitamin B3 are typically met through the diet, recent studies have shown that additional supplementation with NR may be an effective method to counter the age-related decline in NAD+ levels as NR bypasses the rate-limiting step in NAD+ biosynthesis. Furthermore, pharmaceutical applications of NR for age-related disorders have been proposed. In this study, the safety of a high-purity, nature-identical, synthetic NR (NR-E), manufactured under the guidelines of good manufacturing practices for dietary supplements (21 CFR 111) as well as for drugs (21 CFR 210), was investigated in a 90-day oral toxicity study in Sprague Dawley rats at 300, 500, and 1,200 mg/kg/d. There were no mortality or clinical observations attributable to the test substance at any dose. A small but statistically significant decrease in body weight was observed at day 92 in the 1,200 mg/kg/d NR-treated male rats only. In contrast to a previously published safety assessment using a different synthetic NR (NIAGEN), whose no-observed-adverse-effect-level (NOAEL) was reported to be 300 mg/kg/d, there were no adverse changes in clinical pathology parameters and no notable macroscopic or microscopic findings or treatment-related effects at similar doses. In the current study, the NOAEL for systemic toxicity of NR-E in Sprague-Dawley rats was conservatively determined to be 500 mg/kg/d for males (solely based on body weight) and 1,200 mg/kg/d for females.

Rate of brain aging and APOE ε4 are synergistic risk factors for Alzheimer's disease.

Advanced age and the APOE ε4 allele are the two biggest risk factors for Alzheimer's disease (AD) and declining cognitive function. We describe a universal gauge to measure molecular brain age using transcriptome analysis of four human postmortem cohorts (n = 673, ages 25-97) free of neurological disease. In a fifth cohort of older subjects with or without neurological disease (n = 438, ages 67-108), we show that subjects with brains deviating in the older direction from what would be expected based on chronological age show an increase in AD, Parkinson's disease, and cognitive decline. Strikingly, a younger molecular age (-5 yr than chronological age) protects against AD even in the presence of APOE ε4 An established DNA methylation gauge for age correlates well with the transcriptome gauge for determination of molecular age and assigning deviations from the expected. Our results suggest that rapid brain aging and APOE ε4 are synergistic risk factors, and interventions that slow aging may substantially reduce risk of neurological disease and decline even in the presence of APOE ε4.

NAD+ supplementation rejuvenates aged gut adult stem cells.

The tissue decline due to aging is associated with the deterioration of adult stem cell function. Here we show the number and proliferative activity of intestinal stem cells (ISCs) but not Paneth cells decline during aging, as does ISC function assessed ex vivo. Levels of SIRT1 and activity of mTORC1 also decline with aging. The treatment with the NAD(+) precursor nicotinamide riboside (NR) rejuvenates ISCs from aged mice and reverses an impaired ability to repair gut damage. The effect of NR is blocked by the mTORC1 inhibitor rapamycin or the SIRT1 inhibitor EX527. These findings demonstrate that small molecules affecting the NAD/SIRT1/mTORC1 axis may guide a translational path for maintenance of the intestine during aging.

Efficacy and tolerability of EH301 for amyotrophic lateral sclerosis: a randomized, double-blind, placebo-controlled human pilot study.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease, characterized by progressive loss of spinal and cortical motor neurons, leading to muscular atrophy, respiratory failure, and ultimately death. There is no known cure, and the clinical benefit of the two drugs approved to treat ALS remains unclear. Novel disease-modifying therapeutics that are able to modulate the disease course are desperately needed. Our objective was to evaluate the efficacy and tolerability of Elysium Health's candidate drug EH301 in people with ALS (PALS). METHODS: This was a single-center, prospective, double-blind, randomized, placebo-controlled pilot study. Thirty-two PALS were recruited thanks to the collaboration of the Spanish Foundation for ALS Research (FUNDELA). Study participants were randomized to receive either EH301 or placebo and underwent evaluation for 4 months. Differences between EH301 and placebo-treated participants were evaluated based on standard clinical endpoints, including the revised ALS functional rating scale (ALSFRS-R), forced vital capacity (FVC), and the Medical Research Council (MRC) grading scale. RESULTS: Compared to placebo, participants treated with EH301 demonstrated significant improvements in the ALSFRS-R score, pulmonary function, muscular strength, and in skeletal muscle/fat weight ratio. EH301 was shown to significantly slow the progression of ALS relative to placebo, and even showed improvements in several key outcome measures compared with baseline. CONCLUSIONS: This study provides evidence in support of the disease-modifying effects of EH301 for the treatment of ALS.

SIRT1 deacetylase in aging-induced neuromuscular degeneration and amyotrophic lateral sclerosis.

SIRT1 is an NAD+ -dependent deacetylase that functions in a variety of cells and tissues to mitigate age-associated diseases. However, it remains unknown if SIRT1 also acts to prevent pathological changes that accrue in motor neurons during aging and amyotrophic lateral sclerosis (ALS). In this study, we show that SIRT1 expression decreases in the spinal cord of wild-type mice during normal aging. Using mouse models either overexpressing or lacking SIRT1 in motor neurons, we found that SIRT1 slows age-related degeneration of motor neurons' presynaptic sites at neuromuscular junctions (NMJs). Transcriptional analysis of spinal cord shows an overlap of greater than 90% when comparing alterations during normal aging with changes during ALS, revealing a substantial upregulation in immune and inflammatory response genes and a downregulation of synaptic transcripts. In addition, overexpressing SIRT1 in motor neurons delays progression to end-stage disease in high copy SOD1G93A mice. Thus, our findings suggest that there are parallels between ALS and aging, and interventions to impede aging may also slow the progression of this devastating disease.

Erratum: Author Correction: Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD+ levels in humans safely and sustainably: a randomized, double-blind, placebo-controlled study.

[This corrects the article DOI: 10.1038/s41514-017-0016-9.].

Impairment of an Endothelial NAD+-H2S Signaling Network Is a Reversible Cause of Vascular Aging.

A decline in capillary density and blood flow with age is a major cause of mortality and morbidity. Understanding why this occurs is key to future gains in human health. NAD precursors reverse aspects of aging, in part, by activating sirtuin deacylases (SIRT1-SIRT7) that mediate the benefits of exercise and dietary restriction (DR). We show that SIRT1 in endothelial cells is a key mediator of pro-angiogenic signals secreted from myocytes. Treatment of mice with the NAD+ booster nicotinamide mononucleotide (NMN) improves blood flow and increases endurance in elderly mice by promoting SIRT1-dependent increases in capillary density, an effect augmented by exercise or increasing the levels of hydrogen sulfide (H2S), a DR mimetic and regulator of endothelial NAD+ levels. These findings have implications for improving blood flow to organs and tissues, increasing human performance, and reestablishing a virtuous cycle of mobility in the elderly.

DEP domain-containing mTOR-interacting protein suppresses lipogenesis and ameliorates hepatic steatosis and acute-on-chronic liver injury in alcoholic liver disease.

Alcoholic liver disease (ALD) is characterized by lipid accumulation and liver injury. However, how chronic alcohol consumption causes hepatic lipid accumulation remains elusive. The present study demonstrates that activation of the mechanistic target of rapamycin complex 1 (mTORC1) plays a causal role in alcoholic steatosis, inflammation, and liver injury. Chronic-plus-binge ethanol feeding led to hyperactivation of mTORC1, as evidenced by increased phosphorylation of mTOR and its downstream kinase S6 kinase 1 (S6K1) in hepatocytes. Aberrant activation of mTORC1 was likely attributed to the defects of the DEP domain-containing mTOR-interacting protein (DEPTOR) and the nicotinamide adenine dinucleotide-dependent deacetylase sirtuin 1 (SIRT1) in the liver of chronic-plus-binge ethanol-fed mice and in the liver of patients with ALD. Conversely, adenoviral overexpression of hepatic DEPTOR suppressed mTORC1 signaling and ameliorated alcoholic hepatosteatosis, inflammation, and acute-on-chronic liver injury. Mechanistically, the lipid-lowering effect of hepatic DEPTOR was attributable to decreased proteolytic processing, nuclear translocation, and transcriptional activity of the lipogenic transcription factor sterol regulatory element-binding protein-1 (SREBP-1). DEPTOR-dependent inhibition of mTORC1 also attenuated alcohol-induced cytoplasmic accumulation of the lipogenic regulator lipin 1 and prevented alcohol-mediated inhibition of fatty acid oxidation. Pharmacological intervention with rapamycin alleviated the ability of alcohol to up-regulate lipogenesis, to down-regulate fatty acid oxidation, and to induce steatogenic phenotypes. Chronic-plus-binge ethanol feeding led to activation of SREBP-1 and lipin 1 through S6K1-dependent and independent mechanisms. Furthermore, hepatocyte-specific deletion of SIRT1 disrupted DEPTOR function, enhanced mTORC1 activity, and exacerbated alcoholic fatty liver, inflammation, and liver injury in mice. CONCLUSION: The dysregulation of SIRT1-DEPTOR-mTORC1 signaling is a critical determinant of ALD pathology; targeting SIRT1 and DEPTOR and selectively inhibiting mTORC1-S6K1 signaling may have therapeutic potential for treating ALD in humans. (Hepatology 2018).

Sirt3 deficiency does not affect venous thrombosis or NETosis despite mild elevation of intracellular ROS in platelets and neutrophils in mice.

Inflammation is a common denominator in chronic diseases of aging. Yet, how inflammation fuels these diseases remains unknown. Neutrophils are the primary leukocytes involved in the early phase of innate immunity and inflammation. As part of their anti-microbial defense, neutrophils form extracellular traps (NETs) by releasing decondensed chromatin lined with cytotoxic proteins. NETs have been shown to induce tissue injury and thrombosis. Here, we demonstrated that Sirt3, a nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase, an enzyme linked to human longevity, was expressed in mouse neutrophils and platelets. Using Sirt3-/- mice as a model of accelerated aging, we investigated the effects of Sirt3 deficiency on NETosis and platelet function, aiming to detect enhancement of thrombosis. More mitochondrial reactive oxygen species (ROS) were generated in neutrophils and platelets of Sirt3-/- mice compared to WT, when stimulated with a low concentration of phorbol 12-myristate 13-acetate (PMA) and a high concentration of thrombin, respectively. There were no differences in in vitro NETosis, with or without stimulation. Platelet aggregation was mildly augmented in Sirt3-/- mice compared to WT mice, when stimulated with a low concentration of collagen. The effect of Sirt3 deficiency on platelet and neutrophil activation in vivo was examined by the venous thrombosis model of inferior vena cava stenosis. Elevation of plasma DNA concentration was observed after stenosis in both genotypes, but no difference was shown between the two genotypes. The systemic response to thrombosis was enhanced in Sirt3-/- mice with significantly elevated neutrophil count and reduced platelet count. However, no differences were observed in incidence of thrombus formation, thrombus weight and thrombin-antithrombin complex generation between WT and Sirt3-/- mice. We conclude that Sirt3 does not considerably impact NET formation, platelet function, or venous thrombosis in healthy young mice.

Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD+ levels in humans safely and sustainably: a randomized, double-blind, placebo-controlled study.

NRPT is a combination of nicotinamide riboside (NR), a nicotinamide adenine dinucleotide (NAD+) precursor vitamin found in milk, and pterostilbene (PT), a polyphenol found in blueberries. Here, we report this first-in-humans clinical trial designed to assess the safety and efficacy of a repeat dose of NRPT (commercially known as Basis). NRPT was evaluated in a randomized, double-blind, and placebo-controlled study in a population of 120 healthy adults between the ages of 60 and 80 years. The study consisted of three treatment arms: placebo, recommended dose of NRPT (NRPT 1X), and double dose of NRPT (NRPT 2X). All subjects took their blinded supplement daily for eight weeks. Analysis of NAD+ in whole blood demonstrated that NRPT significantly increases the concentration of NAD+ in a dose-dependent manner. NAD+ levels increased by approximately 40% in the NRPT 1X group and approximately 90% in the NRPT 2X group after 4 weeks as compared to placebo and baseline. Furthermore, this significant increase in NAD+ levels was sustained throughout the entire 8-week trial. NAD+ levels did not increase for the placebo group during the trial. No serious adverse events were reported in this study. This study shows that a repeat dose of NRPT is a safe and effective way to increase NAD+ levels sustainably.

SIRT1 is a positive regulator of in vivo bone mass and a therapeutic target for osteoporosis.

Overexpression or pharmacological activation of SIRT1 has been shown to extend the lifespan of mice and protect against aging-related diseases. Here we show that pharmacological activation of SIRT1 protects in two models of osteoporosis. Ovariectomized female mice and aged male mice, models for post-menopausal and aging-related osteoporosis, respectively, show significant improvements in bone mass upon treatment with SIRT1 agonist, SRT1720. Further, we find that calorie restriction (CR) results in a two-fold upregulation of sirt1 mRNA expression in bone tissue that is associated with increased bone mass in CR mice. Reciprocally, SIRT1 whole-body knockout (KO) mice, as well as osteoblast and osteoclast specific KOs, show a low bone mass phenotype; though double knockout mice (containing SIRT1 deleted in both osteoblasts and osteoclasts) do not show a more severe phenotype. Altogether, these findings provide strong evidence that SIRT1 is a positive regulator of bone mass and a promising target for the development of novel therapeutics for osteoporosis.

The brain, sirtuins, and ageing.

In mammals, recent studies have demonstrated that the brain, the hypothalamus in particular, is a key bidirectional integrator of humoral and neural information from peripheral tissues, thus influencing ageing both in the brain and at the 'systemic' level. CNS decline drives the progressive impairment of cognitive, social and physical abilities, and the mechanisms underlying CNS regulation of the ageing process, such as microglia-neuron networks and the activities of sirtuins, a class of NAD+-dependent deacylases, are beginning to be understood. Such mechanisms are potential targets for the prevention or treatment of age-associated dysfunction and for the extension of a healthy lifespan.