Full Length ArticleTargeting sirtuin activity with nicotinamide riboside reduces neuroinflammation in a GWI mouse model
Introduction
Nearly thirty years have elapsed since the 1991 Gulf War (GW) conflict, but 30% of veterans from this conflict continue to suffer from Gulf War Illness (GWI) and experience debilitating symptoms such as pain, fatigue and memory problems (Binns et al., 2008; White et al., 2016). Both clinical and animal studies suggest that disturbances in bioenergetics may be part of the underlying pathological features associated with the heterogeneous symptoms experienced by veterans with GWI (Abdullah et al., 2016; Shetty et al., 2017; Koslik et al., 2014; Rayhan et al., 2013a). Several imaging studies have shown abnormal levels of bioenergetics markers in the brains of veterans with GWI (Rayhan et al., 2013b; Rayhan et al., 2013c). Therefore, therapies that are aimed at improving mitochondrial bioenergetics in the brain may help with improving the general health and well-being of veterans with GWI.
Energy disturbances in veterans with GWI are characterized by increases in lipid peroxidation products in plasma, changes in mitochondrial plasma lipids, inability to recover phosphocreatine levels in muscle after exercise, and damage to mitochondrial DNA corresponding with reduced activity of mitochondrial enzymes involved in electron transport chain (ETC) and anti-oxidant defense (Abdullah et al., 2016; Koslik et al., 2014; Chen et al., 2017; Joshi et al., 2018). Evidence for central nervous system (CNS) bioenergetics disturbances is suggested by a study showing increased lactate utilization in the prefrontal cortex following an exercise challenge in a subset of veterans with GWI and glucose hypometabolism in the hippocampus of GW veterans with GWI (Rayhan et al., 2013a). In a GWI mouse model, neurobehavioral deficits corresponded with decreases in the Krebs cycle intermediary compounds and downregulation of pathways related to the conversion of pyruvate to lactate and gluconeogenesis (Abdullah et al., 2016). Lipid analysis of this mouse model showed alterations in mitochondria-specific lipids, such as cardiolipin (CL) and acylcarnitine levels in the brains of GWI mice (Abdullah et al., 2016). A decrease in several ETC enzymes was also observed in the brains of GW chemical-exposed mice (Zakirova et al., 2017). A rat model of GW chemical exposure also showed chronic oxidative stress, inflammation, and mitochondrial dysfunction along with memory and mood dysfunction in exposed rats (Shetty et al., 2017; Parihar et al., 2013). These studies suggest that mitochondria dysfunction may be a contributory factor in bioenergetics deficits in GWI, as it has been observed both in veterans with this condition and in mouse models developed using GW-relevant chemical exposures.
Nicotinamide adenine dinucleotide (NAD+) is an important cofactor of many metabolic processes, including glycolysis, fatty acid β-oxidation and the Krebs cycle, while its reduced form, NADH, serves as an electron-rich source that takes part in oxidative phosphorylation (OXPHOS), ultimately contributing to the generation of adenosine triphosphate (ATP) as energy (Berger et al., 2004; Ruggieri et al., 2015). During OXPHOS, NAD+/NADH simply shuttle electrons and are not consumed during this process. However, NAD + is actively consumed by sirtuins during the protein deacetylation process (Sauve, 2010). It is well known that NAD + increases the expression and the activity of sirtuins (Sauve et al., 2006; ichiro and Guarente, 2014), which corresponds with reduced inflammation via nuclear-factor κB (NFκB) mediated pathways and targets mitochondria biogenesis through activation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)-dependent pathways (Chong et al., 2012; Hou et al., 2018; Hasan-Olive et al., 2019). Although the exact mechanisms remain unknown, depletion of NAD + or its reduced form NADH is considered a hallmark of aging and is also observed in chronic fatigue syndrome (CFS), which has some clinical resemblance to GWI (Alegre et al., 2010; Sun et al., 2016; Camacho-Pereira et al., 2016; Mikirova et al., 2012; Fang et al., 2017).
Given the importance of NAD + in cellular bioenergetics, various approaches have been explored for supplementing NAD+ (Hou et al., 2018; Lee and Yang, 2019; Cantó et al., 2012). Supplementation with the NAD + precursor nicotinamide riboside (NR) appears to be a viable option as this form of NAD + can enter the cell and cross the blood-brain-barrier (BBB) (Spector and Johanson, 2007). In the cell, NR is converted to NAD + by an enzyme nicotinamide riboside kinase (NRK) (Wang et al., 2018). Supplementation with NR in animal models of neurodegeneration reduces inflammation and attenuates neuropathological phenotypes through sirtuin-1 (Sirt1)-mediated deacetylation of the NFκB pathway (Hou et al., 2018; Chen et al., 2018). Others have shown that NR treatment enhances cognitive functioning and reduces glial activation (Hou et al., 2018; Liu et al., 2013). Treatment with NR may be a valuable therapeutic approach due to its high bioavailability and minimal toxicity in humans (Trammell et al., 2016). In a pilot human study, levels of NAD + rose by 3-fold after a single oral dose of 300 mg of NR (Trammell et al., 2016). We therefore hypothesize that NR treatment may reduce disturbances in mitochondrial bioenergetics, oxidative stress and chronic neuroinflammation. We therefore tested NR in a mouse model of GWI that exhibits neurobehavioral and brain bioenergetics deficits and neuroinflammation that are relevant to the etiology of GWI. The studies described below provide preclinical evidence for potential use of NR in treating the bioenergetic deficits in this GWI mouse model and provides translational relevance of these findings to veterans with GWI.
Section snippets
Human subject
As described previously, human plasma samples were utilized from 2 different cohorts: (1) Veterans with GWI and healthy GW-deployed control veterans recruited at the Roskamp Institute Clinic and (2) GWI cases and healthy GW-deployed control veterans from the Boston Gulf War Illness Consortium(GWIC) (Abdullah et al., 2016; Joshi et al., 2018; Janulewicz et al., 2018). The Roskamp Institute Clinic study was approved by the Western Institutional Review Board (IRB) and the protocol and procedures
GWI is associated with low NAD and Sirt1 levels in the plasma
We examined plasma NAD and Sirt1 protein levels in PBMC in a pilot cross-sectional study of age- and gender-similar healthy GW veterans and those with GWI (see demographics in Table 1). These studies showed that NAD (t-test(df= 12) = 8.51, p = 0.002, Fig. 2A) and Sirt1 (t-test (df= 16) = 22.75, p = 0.083, Fig. 2B) levels were decreased in veterans with GWI compared to controls. There was a 2-fold decrease in NAD and 1.6-fold decrease in Sirt1 level in GWI compared to healthy controls.
Nicotinamide riboside improves fatigue-like behavior in GWI mice
To
Discussion
Dysregulated mitochondria function in GWI is characterized by altered bioenergetics molecules, increased oxidative stress, and abnormal levels of mitochondrial metabolites in mouse models and in veterans with GWI (Abdullah et al., 2016; Shetty et al., 2017; Koslik et al., 2014; Chen et al., 2017). We show significant decreases in NAD and Sirt1 protein levels in veterans with GWI, which were also seen in a mouse model of GWI. Since NR is shown to specifically target NAD recovery (Trammell et
Funding
This work is supported by a VA Merit award (1I01RX002260-01A1) and a CDMRP award (GW150056) to Dr. Laila Abdullah, a CDMRP consortium award (GW120037) to Dr. Kimberly Sullivan, a VA merit and a CDMRP award to Dr. Nancy Klimas.
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
CRediT authorship contribution statement
Utsav Joshi: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Data curation, Writing - original draft, Writing - review & editing. James E. Evans: Conceptualization, Methodology, Validation, Investigation, Resources, Data curation, Supervision. Andrew Pearson: Resources, Data curation. Nicole Saltiel: Methodology, Investigation, Resources, Data curation. Adam Cseresznye: . Teresa Darcey: Formal analysis. Joseph Ojo: Resources, Data curation. Andrew P.
References (56)
- et al.
Recent research on Gulf War illness and other health problems in veterans of the 1991 Gulf War: Effects of toxicant exposures during deployment
Cortex
(2016) - et al.
Translational potential of long-term decreases in mitochondrial lipids in a mouse model of Gulf War Illness
Toxicology
(2016) - et al.
Effects of low-level exposure to sarin and cyclosarin during the 1991 Gulf War on brain function and brain structure in US veterans
NeuroToxicology
(2010) - et al.
Gulf War Illness and the Health of Gulf War Veterans: Scientific Findings and Recommendations
(2008) - et al.
Chronic Oxidative Stress, Mitochondrial Dysfunction, Nrf2 Activation and Inflammation in the Hippocampus Accompany Heightened Systemic Inflammation and Oxidative Stress in an Animal Model of Gulf War Illness
Frontiers in Molecular Neuroscience
(2017) - et al.
Mitochondrial dysfunction in Gulf War illness revealed by 31phosphorus magnetic resonance spectroscopy: A case-control study
PLoS ONE
(2014) - et al.
Prefrontal lactate predicts exercise-induced cognitive dysfunction in Gulf War Illness
American Journal of Translational Research
(2013) - et al.
Increased Brain White Matter Axial Diffusivity Associated with Fatigue, Pain and Hyperalgesia in Gulf War Illness
PLoS ONE
(2013) - et al.
Exercise Challenge in Gulf War Illness Reveals Two Subgroups with Altered Brain Structure and Function
PLoS ONE
(2013) - et al.
Role of mitochondrial DNA damage and dysfunction in veterans with Gulf War Illness
PLoS ONE
(2017)
Oleoylethanolamide treatment reduces neurobehavioral deficits and brain pathology in a mouse model of Gulf War Illness
Scientific Reports
Complementary proteomic approaches reveal mitochondrial dysfunction, immune and inflammatory dysregulation in a mouse model of Gulf War Illness
Proteomics - Clinical Applications
Mood and memory deficits in a model of Gulf War illness are linked with reduced neurogenesis, partial neuron loss, and mild inflammation in the hippocampus
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
The new life of a centenarian: Signalling functions of NAD(P)
Trends in Biochemical Sciences
Regulation of NAD biosynthetic enzymes modulates NAD-sensing processes to shape mammalian cell physiology under varying biological cues
Biochimica et Biophysica Acta - Proteins and Proteomics
Sirtuin chemical mechanisms
Biochimica et Biophysica Acta - Proteins and Proteomics
The Biochemistry of Sirtuins
Annual Review of Biochemistry
NAD+ and sirtuins in aging and disease
Trends in Cell Biology
SIRT1: new avenues of discovery for disorders of oxidative stress
Expert Opinion on Therapeutic Targets
NAD + supplementation normalizes key Alzheimer’s features and DNA damage responses in a new AD mouse model with introduced DNA repair deficiency
Proceedings of the National Academy of Sciences.
A Ketogenic Diet Improves Mitochondrial Biogenesis and Bioenergetics via the PGC1α-SIRT3-UCP2 Axis
Neurochemical Research
Nicotinamide adenine dinucleotide (NADH) in patients with chronic fatigue syndrome. [Spanish] Nicotinamida adenina dinucleotido (NADH) en pacientes con sindrome de fatiga cronica
Revista clínica española
The Mitochondrial Basis of Aging
Molecular Cell
CD38 Dictates Age-Related NAD Decline and Mitochondrial Dysfunction through an SIRT3-Dependent Mechanism
Cell Metabolism
The assessment of the energy metabolism in patients with chronic fatigue syndrome by serum fluorescence emission
Alternative Therapies in Health and Medicine
NAD + in Aging: Molecular Mechanisms and Translational Implications
Trends in Molecular Medicine
Nicotinamide riboside regulates inflammation and mitochondrial markers in AML12 hepatocytes
Nutrition Research and Practice
The NAD+ precursor nicotinamide riboside enhances oxidative metabolism and protects against high-fat diet-induced obesity
Cell Metabolism
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2021, Pharmacology and TherapeuticsCitation Excerpt :During NR treatment, GWI mice were investigated for fatigue-like behavior using FST. The results showed that NR treatment diminished fatigue-like behavior with increased levels of NAD+ levels in the circulating blood and the brain, and enhanced Sirt1 and Sirt3 levels in the brain (Joshi et al., 2020). Also, NR treated GWI mice displayed deacetylation of NF-κB p65 subunit, increased concentration of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha, and reduced astrocyte activity in the brain.