Transcriptome analysis reveals intermittent fasting-induced genetic changes in ischemic stroke

Circadian-Dependent Intermittent Fasting Influences Ischemic Tolerance and Dendritic Spine Remodeling

BACKGROUND

Preconditioning by intermittent fasting is linked to improved cognition and motor function, and enhanced recovery after stroke. Although the duration of fasting was shown to elicit different levels of neuroprotection after ischemic stroke, the impact of time of fasting with respect to the circadian cycles remains unexplored.

METHODS

Cohorts of mice were subjected to a daily 16-hour fast, either during the dark phase (active-phase intermittent fasting) or the light phase (inactive-phase intermittent fasting) or were fed ad libitum. Following a 6-week dietary regimen, mice were subjected to transient focal cerebral ischemia and underwent behavioral functional assessment. Brain samples were collected for RNA sequencing and histopathologic analyses.

RESULTS

Active-phase intermittent fasting cohort exhibited better poststroke motor and cognitive recovery as well as reduced infarction, in contrast to inactive-phase intermittent fasting cohort, when compared with ad libitum cohort. In addition, protection of dendritic spine density/morphology and increased expression of postsynaptic density protein-95 were observed in the active-phase intermittent fasting.

CONCLUSIONS

These findings indicate that the time of daily fasting is an important factor in inducing ischemic tolerance by intermittent fasting.

Intermittent Metabolic Switching and Vascular Cognitive Impairment

Intermittent fasting (IF), a dietary pattern alternating between eating and fasting periods within a 24-hour cycle, has garnered recognition for its potential to enhance both healthspan and lifespan in animal models and humans. It also shows promise in alleviating age-related diseases, including neurodegeneration. Vascular cognitive impairment (VCI) spans a severity range from mild cognitive deficits to severe cognitive deficits and loss of function in vascular dementia. Chronic cerebral hypoperfusion has emerged as a significant contributor to VCI, instigating vascular pathologies such as microbleeds, blood-brain barrier dysfunction, neuronal loss, and white matter lesions. Preclinical studies in rodents strongly suggest that IF has the potential to attenuate pathological mechanisms, including excitotoxicity, oxidative stress, inflammation, and cell death pathways in VCI models. Hence, this supports evaluating IF in clinical trials for both existing and at-risk VCI patients. This review compiles existing data supporting IF's potential in treating VCI-related vascular and neuronal pathologies, emphasizing the mechanisms by which IF may mitigate these issues. Hence providing a comprehensive overview of the available data supporting IF's potential in treating VCI by emphasizing the underlying mechanisms that make IF a promising intervention for VCI.

Immune and metabolic challenges induce changes in pain sensation and related pathways in the hypothalamus

The hypothalamic molecular processes participate in the regulation of the neuro-immune-endocrine system, including hormone, metabolite, chemokine circulation, and corresponding physiological and behavioral responses. RNA-sequencing profiles were analyzed to understand the effect of juvenile immune and metabolic distress 100 days after virally elicited maternal immune activation during gestation in pigs. Over 1,300 genes exhibited significant additive or interacting effects of gestational immune activation, juvenile distress, and sex. One-third of these genes presented multiple effects, emphasizing the complex interplay of these factors. Key functional categories enriched among affected genes included sensory perception of pain, steroidogenesis, prolactin, neuropeptide, and inflammatory signaling. These categories underscore the intricate relationship between gestational immune activation during gestation, distress, and the response of hypothalamic pathways to insults. These effects were sex-dependent for many genes, such as Prdm12, Oprd1, Isg20, Prl, Oxt, and Vip. The prevalence of differentially expressed genes annotated to proinflammatory and cell cycle processes suggests potential implications for synaptic plasticity and neuronal survival. The gene profiles affected by immune activation, distress, and sex pointed to the action of transcription factors SHOX2, STAT1, and REST. These findings underscore the importance of considering sex and postnatal challenges when studying causes of neurodevelopmental disorders and highlight the complexity of the "two-hit" hypothesis in understanding their etiology. Our study furthers the understanding of the intricate molecular responses in the hypothalamus to gestational immune activation and subsequent distress, shedding light on the sex-specific effects and the potential long-lasting consequences on pain perception, neuroendocrine regulation, and inflammatory processes.NEW & NOTEWORTHY The interaction of infection during gestation and insults later in life influences the molecular mechanisms in the hypothalamus that participate in pain sensation. The response of the hypothalamic transcriptome varies between sexes and can also affect synapses and immune signals. The findings from this study assist in the identification of agonists or antagonists that can guide pretranslational studies to ameliorate the effects of gestational insults interacting with postnatal challenges on physiological or behavioral disorders.

Intermittent fasting in health and disease

CONTEXT

Intermittent fasting, a new-age dietary concept derived from an age-old tradition, involves repetitive cycles of fasting/calorie restriction and eating.

OBJECTIVE

We aim to take a deep dive into the biological responses to intermittent fasting, delineate the disease-modifying and cognitive effects of intermittent fasting, and also shed light on the possible side effects.

METHODS

Numerous in vitro and in vivo studies were reviewed, followed by an in-depth analysis, and compilation of their implications in health and disease.

RESULTS

Intermittent fasting improves the body's stress tolerance, which is further amplified with exercise. It impacts various pathological conditions like cancer, obesity, diabetes, cardiovascular disease, and neurodegenerative diseases.

CONCLUSION

During dietary restriction, the human body experiences a metabolic switch due to the depletion of liver glycogen, which promotes a shift towards utilising fatty acids and ketones in the system, thereby significantly impacting adiposity, ageing and the immune response to various diseases.

Multiomics analyses reveal dynamic bioenergetic pathways and functional remodeling of the heart during intermittent fasting

Intermittent fasting (IF) has been shown to reduce cardiovascular risk factors in both animals and humans, and can protect the heart against ischemic injury in models of myocardial infarction. However, the underlying molecular mechanisms behind these effects remain unclear. To shed light on the molecular and cellular adaptations of the heart to IF, we conducted comprehensive system-wide analyses of the proteome, phosphoproteome, and transcriptome, followed by functional analysis. Using advanced mass spectrometry, we profiled the proteome and phosphoproteome of heart tissues obtained from mice that were maintained on daily 12- or 16 hr fasting, every-other-day fasting, or ad libitum control feeding regimens for 6 months. We also performed RNA sequencing to evaluate whether the observed molecular responses to IF occur at the transcriptional or post-transcriptional levels. Our analyses revealed that IF significantly affected pathways that regulate cyclic GMP signaling, lipid and amino acid metabolism, cell adhesion, cell death, and inflammation. Furthermore, we found that the impact of IF on different metabolic processes varied depending on the length of the fasting regimen. Short IF regimens showed a higher correlation of pathway alteration, while longer IF regimens had an inverse correlation of metabolic processes such as fatty acid oxidation and immune processes. Additionally, functional echocardiographic analyses demonstrated that IF enhances stress-induced cardiac performance. Our systematic multi-omics study provides a molecular framework for understanding how IF impacts the heart's function and its vulnerability to injury and disease.

Transcriptomic analysis reveals novel age-independent immunomodulatory proteins as a mode of cerebroprotection in P2X4R KO mice after ischemic stroke

Identification of new potential drug target proteins and their plausible mechanisms for stroke treatment is critically needed. We previously showed that genetic deletion and short-term pharmacological inhibition of P2X4R, a purinergic receptor for adenosine triphosphate ATP, provides acute cerebroprotection. However, potential mechanisms remain unknown. Therefore, we employed RNA-seq technology to identify the gene expression profiles, pathway analysis, and qPCR validation of differentially expressed genes (DEGs). This analysis identified roles of DEGs in certain biological processes responsible for P2X4R-dependent cerebroprotection after stroke. We subjected both young and aged male and female global P2X4 KO and littermate WT mice to ischemic stroke. After 3 days, mice were sacrificed, total RNA was isolated using Trizol, and subjected to RNA-seq and Nanostring-mediated qPCR. DESeq2, Gene Ontology (GO), and Ingenuity Pathway Analysis (IPA) were used to identify mRNA transcript expression profiles and biological pathways. We found 2246 DEGs in P2X4R KO vs WT tissue after stroke. Out of these DEGs, 1920 gene were downregulated, and 325 genes were upregulated in KO. GO/IPA analysis of the top 300 DEGs suggests an enrichment of inflammation and extracellular matrix component genes. qPCR validation of the top 30 DEGs revealed downregulation of two common age-independent genes in P2X4R KO mice: Interleukin-6 ( IL-6) , an inflammatory cytokine, and Cytotoxic T Lymphocyte-Associated Protein 2 alpha ( Ctla2a ), an immunosuppressive factor. These data suggest that P2X4R-mediated cerebroprotection after stroke is initiated by attenuation of immune modulatory pathways in both young and aged mice of both sexes.

Implications of Hypothalamic Neural Stem Cells on Aging and Obesity-Associated Cardiovascular Diseases

The hypothalamus, one of the major regulatory centers in the brain, controls various homeostatic processes, and hypothalamic neural stem cells (htNSCs) have been observed to interfere with hypothalamic mechanisms regulating aging. NSCs play a pivotal role in the repair and regeneration of brain cells during neurodegenerative diseases and rejuvenate the brain tissue microenvironment. The hypothalamus was recently observed to be involved in neuroinflammation mediated by cellular senescence. Cellular senescence, or systemic aging, is characterized by a progressive irreversible state of cell cycle arrest that causes physiological dysregulation in the body and it is evident in many neuroinflammatory conditions, including obesity. Upregulation of neuroinflammation and oxidative stress due to senescence has the potential to alter the functioning of NSCs. Various studies have substantiated the chances of obesity inducing accelerated aging. Therefore, it is essential to explore the potential effects of htNSC dysregulation in obesity and underlying pathways to develop strategies to address obesity-induced comorbidities associated with brain aging. This review will summarize hypothalamic neurogenesis associated with obesity and prospective NSC-based regenerative therapy for the treatment of obesity-induced cardiovascular conditions.

Fatty acids homeostasis during fasting predicts protection from chemotherapy toxicity

Fasting exerts beneficial effects in mice and humans, including protection from chemotherapy toxicity. To explore the involved mechanisms, we collect blood from humans and mice before and after 36 or 24 hours of fasting, respectively, and measure lipid composition of erythrocyte membranes, circulating micro RNAs (miRNAs), and RNA expression at peripheral blood mononuclear cells (PBMCs). Fasting coordinately affects the proportion of polyunsaturated versus saturated and monounsaturated fatty acids at the erythrocyte membrane; and reduces the expression of insulin signaling-related genes in PBMCs. When fasted for 24 hours before and 24 hours after administration of oxaliplatin or doxorubicin, mice show a strong protection from toxicity in several tissues. Erythrocyte membrane lipids and PBMC gene expression define two separate groups of individuals that accurately predict a differential protection from chemotherapy toxicity, with important clinical implications. Our results reveal a mechanism of fasting associated with lipid homeostasis, and provide biomarkers of fasting to predict fasting-mediated protection from chemotherapy toxicity.

Fasting has been reported to protect from chemotherapy-associated toxicity. Here, the authors show that fatty acid profiles in erythrocyte membranes and gene expression from peripheral blood mononuclear cells are associated to the fasting-mediated benefits during cancer treatment in mice and patients.

LncRNA PEG11as silencing sponges miR-874-3p to alleviate cerebral ischemia stroke via regulating autophagy in vivo and in vitro

Long non-coding RNAs (lncRNAs) are reportedly involved in the regulation of physiological and pathophysiological processes. However, the potential role of lncRNAs in stroke remains largely undefined. Here, RNA-Seq analysis of lncRNAs found that the lncRNA PEG11as (PEG11as) levels were significantly increased in ischemic brain tissue in a transient middle cerebral artery occlusion/reperfusion (tMCAO/R) mouse model of stroke. To explore the role of PEG11as in stroke, the lentivirus containing PEG11as silencing construct(siRNA-PEG11as) was microinjected intracerebroventricularly into male or transfected to N2a cells and then exposed to tMCAO/R or oxygen-glucose deprivation/reoxygenation (OGD/R). Knockdown of PEG11as expression significantly reduced infarct volume, alleviated neuronal deficits and inhibited neuronal apoptosis in tMCAO/R mice. Mechanistically, as an endogenous microRNA-874-3p (miR-874-3p) sponge, PEG11as silencing inhibited miR-874-3p activity, resulting in downregulation of ATG16L1 expression and subsequent inhibition of neuronal apoptosis by regulating autophagy. Overall, the results of this current study indicate that PEG11as is involved in the pathophysiology of cerebral ischemia, thus providing translational evidence that PEG11as can be envisioned as a novel biomarker or/and therapeutic target for stroke.

Intermittent fasting induces chronic changes in the hepatic gene expression of Red Jungle Fowl (Gallus gallus)

Background

Intermittent fasting (IF), the implementation of fasting periods of at least 12 consecutive hours on a daily to weekly basis, has received a lot of attention in recent years for imparting the life-prolonging and health-promoting effects of caloric restriction with no or only moderate actual restriction of caloric intake. IF is also widely practiced in the rearing of broiler breeders, the parent stock of meat-type chickens, who require strict feed restriction regimens to prevent the serious health problems associated with their intense appetites. Although intermittent fasting has been extensively used in this context to reduce feed competition and its resulting stress, the potential of IF in chickens as an alternative and complementary model to rodents has received less investigation. In both mammals and birds, the liver is a key component of the metabolic response to IF, responding to variations in energy balance. Here we use a microarray analysis to examine the liver transcriptomics of wild-type Red Jungle Fowl chickens fed either ad libitum, chronically restricted to around 70% of ad libitum daily or intermittently fasted (IF) on a 2:1 (2 days fed, 1 day fasted) schedule without actual caloric restriction. As red junglefowl are ancestral to domestic chicken breeds, these data serve as a baseline to which existing and future transcriptomic results from farmed birds such as broiler breeders can be compared.

Results

We find large effects of feeding regimen on liver transcriptomics, with most of the affected genes relating to energy metabolism. A cluster analysis shows that IF is associated with large and reciprocal changes in genes related to lipid and carbohydrate metabolism, but also chronic changes in genes related to amino acid metabolism (generally down-regulated) and cell cycle progression (generally up-regulated). The overall transcription pattern appears to be one of promoting high proliferative plasticity in response to fluctuations in available energy substrates. A small number of inflammation-related genes also show chronically changed expression profiles, as does one circadian rhythm gene.

Conclusions

The increase in proliferative potential suggested by the gene expression changes reported here indicates that birds and mammals respond similarly to intermittent fasting practices. Our findings therefore suggest that the health benefits of periodic caloric restriction are ubiquitous and not restricted to mammals alone. Whether a common fundamental mechanism, for example involving leptin, underpins these benefits remains to be elucidated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08533-5.

Scientific Evidences of Calorie Restriction and Intermittent Fasting for Neuroprotection in Traumatic Brain Injury Animal Models: A Review of the Literature

It has widely been accepted that food restriction (FR) without malnutrition has multiple health benefits. Various calorie restriction (CR) and intermittent fasting (IF) regimens have recently been reported to exert neuroprotective effects in traumatic brain injury (TBI) through variable mechanisms. However, the evidence connecting CR or IF to neuroprotection in TBI as well as current issues remaining in this research field have yet to be reviewed in literature. The objective of our review was therefore to weigh the evidence that suggests the connection between CR/IF with recovery promotion following TBI. Medline, Google Scholar and Web of Science were searched from inception to 25 February 2022. An overwhelming number of results generated suggest that several types of CR/IF play a promising role in promoting post-TBI recovery. This recovery is believed to be achieved by alleviating mitochondrial dysfunction, promoting hippocampal neurogenesis, inhibiting glial cell responses, shaping neural cell plasticity, as well as targeting apoptosis and autophagy. Further, we represent our views on the current issues and provide thoughts on the future direction of this research field.

An integrated chemo-informatics and in vitro experimental approach repurposes acarbose as a post-ischemic neuro-protectant

The increasing prevalence of ischemic stroke combined with limited therapeutic options highlights the compelling need for continued research into the development of future neuro-therapeutics. Death-Associated Protein Kinase 1 (DAPK1) and p53 protein-protein interaction serve as a signaling point for the convergence of apoptosis and necrosis in cerebral ischemia. In this study, we used an integrated chemo-informatics and in vitro experimental drug repurposing strategy to screen potential small-molecule inhibitors of DAPK1-p53 interaction from the United States of America Food and Drug Administration (FDA) approved drug database exhibiting post-ischemic neuroprotective and neuro-regenerative efficacy and mechanisms. The computational docking and molecular dynamics simulation of FDA-approved drugs followed by an in vitro experimental validation identified acarbose, an anti-diabetic medication and caloric restriction mimetic as a potential inhibitor of DAPK1-p53 interaction. The evaluation of post-ischemic neuroprotective and regenerative efficacy and mechanisms of action for acarbose was carried out using a set of experimental methods, including cell viability, proliferation and differentiation assays, fluorescence staining, and gene expression analysis. Post-ischemic administration of acarbose conferred significant neuroprotection against ischemia-reperfusion injury in vitro. The reduced fluorescence emission in cells stained with _pS²⁰ supported the potential of acarbose in inhibiting the DAPK1-p53 interaction. Acarbose prevented mitochondrial and lysosomal dysfunction, and favorably modulated gene expression related to cell survival, inflammation, and regeneration. BrdU staining and neurite outgrowth assay showed a significant increase in cell proliferation and differentiation in acarbose-treated group. This is the first study known to provide mechanistic insight into the post-ischemic neuroprotective and neuro-regenerative potential of acarbose. Our results provide a strong basis for preclinical studies to evaluate the safety and neuroprotective efficacy of acarbose against ischemic stroke.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-022-03130-5.

Transcriptomic Effects of Healthspan-Promoting Dietary Interventions: Current Evidence and Future Directions

Aging is the greatest risk factor most diseases, including cardiovascular disorders, cancers, diabetes, and neurodegeneration, but select nutritional interventions may profoundly reduce the risk for these conditions. These interventions include calorie restriction, intermittent fasting, protein restriction, and reducing intake of certain amino acids. Certain ad libitum diets, including the Mediterranean, Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability, and Okinawan diets also promote healthy aging. Evidence indicates that these dietary strategies influence aging and healthspan by acting on the biological "hallmarks of aging" and especially upstream nutrient sensing pathways. Recent advances in "omics" technologies, including RNA-sequencing (transcriptomics), have increased our understanding of how such nutritional interventions may influence gene expression related to these biological mediators of aging, primarily in pre-clinical studies. However, whether these effects are also reflected in the human transcriptome, which may provide insight on other downstream/related cellular processes with aging, is an emerging topic. Broadly, the investigation of how these nutritional interventions influence the transcriptome may provide novel insight into pathways associated with aging, and potential targets to treat age-associated disease and increase healthspan. Therefore, the purpose of this mini review is to summarize what is known about the transcriptomic effects of key dietary/nutritional interventions in both pre-clinical models and humans, address gaps in the literature, and provide insight into future research directions.

Exploring the Impact of Cerebrovascular Disease and Major Depression on Non-diseased Human Tissue Transcriptomes

Background

The development of complex diseases is contributed by the combination of multiple factors and complicated interactions between them. Inflammation has recently been associated with many complex diseases and may cause long-term damage to the human body. In this study, we examined whether two types of complex disease, cerebrovascular disease (CVD) or major depression (MD), systematically altered the transcriptomes of non-diseased human tissues and whether inflammation is linked to identifiable molecular signatures, using post-mortem samples from the Genotype-Tissue Expression (GTEx) project.

Results

Following a series of differential expression analyses, dozens to hundreds of differentially expressed genes (DEGs) were identified in multiple tissues between subjects with and without a history of CVD or MD. DEGs from these disease-associated tissues-the visceral adipose, tibial artery, caudate, and spinal cord for CVD; and the hypothalamus, putamen, and spinal cord for MD-were further analyzed for functional enrichment. Many pathways associated with immunological events were enriched in the upregulated DEGs of the CVD-associated tissues, as were the neurological and metabolic pathways in DEGs of the MD-associated tissues. Eight gene-tissue pairs were found to overlap with those prioritized by our transcriptome-wide association studies, indicating a potential genetic effect on gene expression for circulating cytokine phenotypes.

Conclusion

Cerebrovascular disease and major depression cause detectable changes in the gene expression of non-diseased tissues, suggesting that a possible long-term impact of diseases, lifestyles and environmental factors may together contribute to the appearance of "transcriptomic scars" on the human body. Furthermore, inflammation is probably one of the systemic and long-lasting effects of cerebrovascular events.

Much ado about eating: Intermittent fasting and post-stroke neuroprotection

A proper diet is important for health and longevity. Controlling the amount of food consumed is immensely beneficial as it promotes multiple cellular and molecular protective mechanisms and simultaneously prevents toxic mechanisms. Intermittent fasting (IF) is a flexible and easy-to-adopt dietary modification that helps to mitigate metabolic disorders like diabetes and hypertension, and thus the devastating age-related diseases like heart attack, stroke and dementia. The benefits of IF seem to be mediated by altered epigenetic and transcriptional programming leading to reduced oxidative stress, inflammation, mitochondrial damage and cell death.

Intermittent Fasting for Twelve Weeks Leads to Increases in Fat Mass and Hyperinsulinemia in Young Female Wistar Rats

Fasting is known to cause physiological changes in the endocrine pancreas, including decreased insulin secretion and increased reactive oxygen species (ROS) production. However, there is no consensus about the long-term effects of intermittent fasting (IF), which can involve up to 24 hours of fasting interspersed with normal feeding days. In the present study, we analyzed the effects of alternate-day IF for 12 weeks in a developing and healthy organism. Female 30-day-old Wistar rats were randomly divided into two groups: control, with free access to standard rodent chow; and IF, subjected to 24-hour fasts intercalated with 24-hours of free access to the same chow. Alternate-day IF decreased weight gain and food intake. Surprisingly, IF also elevated plasma insulin concentrations, both at baseline and after glucose administration collected during oGTT. After 12 weeks of dietary intervention, pancreatic islets displayed increased ROS production and apoptosis. Despite their lower body weight, IF animals had increased fat reserves and decreased muscle mass. Taken together, these findings suggest that alternate-day IF promote β -cell dysfunction, especially in developing animals. More long-term research is necessary to define the best IF protocol to reduce side effects.

Molecular Mechanisms of Intermittent Fasting-induced Ischemic Tolerance

Diet is a significant factor in determining human well-being. Excessive eating and/or diets with higher than needed amounts of carbohydrates, salt, and fat are known to cause metabolic disorders and functional changes in the body. To compensate the ill effects, many designer diets including the Mediterranean diet, the Okinawa diet, vegetarian/vegan diets, keto diet, anti-inflammatory diet, and the anti-oxidant diet have been introduced in the past 2 decades. While these diets are either enriched or devoid of one or more specific components, a better way to control diet is to limit the amount of food consumed. Caloric restriction (CR), which involves limiting the amount of food consumed rather than eliminating any specific type of food, as well as intermittent fasting (IF), which entails limiting the time during which food can be consumed on a given day, have gained popularity because of their positive effects on human health. While the molecular mechanisms of these 2 dietary regimens have not been fully deciphered, they are known to prolong the life span, control blood pressure, and blood glucose levels. Furthermore, CR and IF were both shown to decrease the incidence of heart attack and stroke, as well as their ill effects. In particular, IF is thought to promote metabolic switching by altering gene expression profiles leading to reduced inflammation and oxidative stress, while increasing plasticity and regeneration.

Intermittent fasting increases adult hippocampal neurogenesis

INTRODUCTION

Intermittent fasting (IF) has been suggested to have neuroprotective effects through the activation of multiple signaling pathways. Rodents fasted intermittently exhibit enhanced hippocampal neurogenesis and long-term potentiation (LTP) at hippocampal synapses compared with sedentary animals fed an ad libitum (AL) diet. However, the underlying mechanisms have not been studied. In this study, we evaluated the mechanistic gap in understanding IF-induced neurogenesis.

METHODS

We evaluated the impact of 3 months of IF (12, 16, and 24 hr of food deprivation on a daily basis) on hippocampal neurogenesis in C57BL/6NTac mice using immunoblot analysis.

RESULTS

Three-month IF significantly increased activation of the Notch signaling pathway (Notch 1, NICD1, and HES5), neurotrophic factor BDNF, and downstream cellular transcription factor, cAMP response element-binding protein (p-CREB). The expression of postsynaptic marker, PSD95, and neuronal stem cell marker, Nestin, was also increased in the hippocampus in response to 3-month IF.

CONCLUSIONS

These findings suggest that IF may increase hippocampal neurogenesis involving the Notch 1 pathway.

Dietary Restriction and Epigenetics: Part I

Biological aging occurs concomitantly with chronological aging and is commonly burdened by the development of age-related conditions, such as neurodegenerative, cardiovascular, and a myriad of metabolic diseases. With a current global shift in disease epidemiology associated with aging and the resultant social, economic, and healthcare burdens faced by many countries, the need to achieve successful aging has fueled efforts to address this problem. Aging is a complex biological phenomenon that has confounded much of the historical research effort to understand it, with still limited knowledge of the underlying molecular mechanisms. Interestingly, dietary restriction (DR) is one intervention that produces anti-aging effects from simple organisms to mammals. Research into DR has revealed robust systemic effects that can result in attenuation of age-related diseases via a myriad of molecular mechanisms. Given that numerous age-associated diseases are often polygenic and affect individuals differently, it is possible that they are confounded by interactions between environmental influences and the genome, a process termed 'epigenetics'. In part one of the review, we summarize the different variants of DR regimens and their corresponding mechanism(s) and resultant effects, as well as in-depth analysis of current knowledge of the epigenetic landscape.

Epigenetic Regulation by Dietary Restriction: Part II

In the first part of our review, we extensively discuss the different variants of dietary restriction (DR) regimens, as well as its corresponding mechanism(s) and subsequent effects. We also provide a detailed analysis of the different epigenetic mechanisms based on current knowledge. We postulate that DR may represent an environmental intervention that can modulate the epigenomic profile of an individual. It is highly plausible that epigenetic regulation by DR may help explain the asymmetric manifestation of DR effects in different individuals. Additionally, epigenetic modifications via DR may lead to epigenetic programming, providing protection against age-associated diseases, which in turn could lead to reduced morbidity and increased lifespan. In the second part of the review, we summarize recent findings that highlight the epigenomic axis of DR, which provides a better understanding of the mechanisms by which its numerous health benefits are achieved.

A Dynamic Transcriptional Analysis Reveals IL-6 Axis as a Prominent Mediator of Surgical Acute Response in Non-ischemic Mouse Heart

Background

Ischemic heart diseases are a major cause of death worldwide. Different animal models, including cardiac surgery, have been developed over time. Unfortunately, the surgery models have been reported to trigger an important inflammatory response that might be an effect modifier, where involved molecular processes have not been fully elucidated yet.

Objective

We sought to perform a thorough characterization of the sham effect in the myocardium and identify the interfering inflammatory reaction in order to avoid misinterpretation of the data via systems biology approaches.

Methods and Results

We combined a comprehensive analytical pipeline of mRNAseq dataset and systems biology analysis to characterize the acute phase response of mouse myocardium at 0 min, 45 min, and 24 h after surgery to better characterize the molecular processes inadvertently induced in sham animals. Our analysis showed that the surgical intervention induced 1209 differentially expressed transcripts (DETs). The clustering of positively co-regulated transcript modules at 45 min fingerprinted the activation of signalization pathways, while positively co-regulated genes at 24 h identified the recruitment of neutrophils and the differentiation of macrophages. In addition, we combined the prediction of transcription factors (TF) regulating DETs with protein-protein interaction networks built from these TFs to predict the molecular network which have induced the DETs. By mean of this retro-analysis of processes upstream gene transcription, we revealed a major role of the Il-6 pathway and further confirmed a significant increase in circulating IL-6 at 45 min after surgery.

Conclusion

This study suggests that a strong induction of the IL-6 axis occurs in sham animals over the first 24 h and leads to the induction of inflammation and tissues’ homeostasis processes.

Genome-Wide Transcriptome Analysis Reveals Intermittent Fasting-Induced Metabolic Rewiring in the Liver

Scope: Intermittent fasting (IF) has been extensively reported to promote improved energy homeostasis and metabolic switching. While IF may be a plausible strategy to ameliorate the epidemiological burden of disease in many societies, our understanding of the underlying molecular mechanisms behind such effects is still lacking. The present study has sought to investigate the relationship between IF and changes in gene expression. We focused on the liver, which is highly sensitive to metabolic changes due to energy status. Mice were randomly assigned to ad libitum feeding or IF for 16 hours per day or for 24 hours on alternate days for 3 months, after which genome-wide transcriptome analysis of the liver was performed using RNA sequencing. Our findings revealed that IF caused robust transcriptomic changes in the liver that led to a complex array of metabolic changes. We also observed that the IF regimen produced distinct profiles of transcriptomic changes, highlighting the significance of temporally different periods of energy restriction. Our results suggest that IF can regulate metabolism via transcriptomic mechanisms and provide insight into how genetic interactions within the liver might lead to the numerous metabolic benefits of IF.

ACC1 (Acetyl Coenzyme A Carboxylase 1) Is a Potential Immune Modulatory Target of Cerebral Ischemic Stroke

Background and Purpose—

Cerebral ischemic stroke elicits profound responses of CD4 + T cells, which in turn significantly affect the ischemic brain injury. ACC1 (acetyl coenzyme A carboxylase 1) is a key enzyme that has been recently found to propagate CD4 + T cell–associated inflammation by mediating de novo fatty acid synthesis; however, its role in the context of ischemic stroke remains unknown.

Methods—

Focal cerebral ischemia was induced by transient middle cerebral artery occlusion for 60 minutes in mice. Seahorse XF glycolysis assay and targeted lipidomic profiling were used to detect metabolic changes in CD4 + T cell after stroke. CD4 cre mice were crossed with ACC1 fl/fl mice to generate the CD4 + T-cell–specific deletion of ACC1 (CD4 cre ACC1 fl/fl mice) mice. Pretreatment with calorie restriction (CR; with 30% reduction of food for 4 weeks before middle cerebral artery occlusion) or post-treatment with ACC1 inhibitor, soraphen A were both used to test the effect of ACC1 modulation on poststroke neuroinflammation.

Results—

Cerebral ischemic stroke increased glycolysis and fatty acid synthesis in peripheral CD4 + T cells, in which the expression of ACC1 was also upregulated. CR downregulated the expression of ACC1 in CD4 + T cells after stroke. Both CD4 cre ACC1 fl/fl mice and CR-pretreated mice exhibited significantly reduced ischemic brain injury and preserved the balance of peripheral regulatory T cells/T helper 17 (Th17) cells. Furthermore, conditional knockout of ACC1 in CD4 + T cells attenuated the protection exerted by CR both on ischemic brain injury and peripheral balance of regulatory T cells/Th17 cells. Pharmacological inhibition of ACC1 after middle cerebral artery occlusion attenuates neuroinflammation, preserves regulatory T cells/Th17 balance, and improves neurological outcomes after ischemic stroke.

Conclusions—

ACC1 is a novel immune metabolic modulation target to balance the regulatory T cells and Th17 cells and blunt neuroinflammation after stroke. Inhibition of ACC1 can be a previously unrecognized mechanism that underlies CR-afforded neuroprotection against cerebral ischemic stroke.

Intermittent fasting increases SOD2 and catalase immunoreactivities in the hippocampus but does not protect from neuronal death following transient ischemia in gerbils

Intermittent fasting has been shown to have neuroprotective effects against transient focal cerebral ischemic insults. However, the effects of intermittent fasting on transient global ischemic insult has not been studied much yet. The present study examined effects of intermittent fasting on endogenous antioxidant enzyme expression levels in the hippocampus and investigated whether the fasting protects neurons 5 days after 5 min of transient global cerebral ischemia. Gerbils were randomly subjected to either ad libitum or alternate-day intermittent fasting for two months and assigned to sham surgery or transient ischemia. Changes of antioxidant enzymes were examined using immunohistochemistry for cytoplasmic superoxide dismutase 1 (SOD1), mitochondrial (SOD2), catalase (CAT), and glutathione peroxidase (GPX). The effects of intermittent fasting on ischemia-induced antioxidant changes, neuronal damage/degeneration and glial activation were examined. The weight of fasting gerbils was not different from that of control gerbils. In controls, SOD1 and GPX immunoreactivities were strong in pyramidal neurons of filed cornu ammonis 1 (CA1). Transient ischemia in controls significantly decreased expressions of SOD1 and GPX in CA1 pyramidal neurons. Intermittent fasting resulted in increased expressions of SOD2 and CAT, not of SOD1 and GPX, in CA1 pyramidal neurons. Nevertheless, CA1 pyramidal neurons were not protected in gerbils subjected to fasting after transient ischemia, and inhibition of glial-cell activation was not observed in the gerbils. In summary, intermittent fasting for two months increased SOD2 and CAT immunoreactivities in hippocampal CA1 pyramidal neurons. However, fasting did not protect the CA1 pyramidal neurons from transient cerebral ischemia. The results of the present study indicate that intermittent fasting may increase certain antioxidants, but not protect neurons from transient global ischemic insult.