The pentose phosphate pathway regulates chronic neuroinflammation and dopaminergic neurodegeneration

Rebalancing redox homeostasis: A pivotal regulator of the cGAS-STING pathway in autoimmune diseases

Autoimmune diseases (ADs) arise from the breakdown of immune tolerance to self-antigens, leading to pathological tissue damage. Proinflammatory cytokine overproduction disrupts redox homeostasis across diverse cell populations, generating oxidative stress that induces DNA damage through multiple mechanisms. Oxidative stress-induced alterations in membrane permeability and DNA damage can lead to the recognition of double-stranded DNA (dsDNA), mitochondrial DNA (mtDNA) and micronuclei-DNA (MN-DNA) by DNA sensors, thereby initiating activation of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. While previous reviews have characterized cGAS-STING activation in autoimmunity, the reciprocal regulation between redox homeostasis and cGAS-STING activation remains insufficiently defined. This narrative review examines oxidative stress-mediated DNA damage as a critical driver of pathological cGAS-STING signaling and delineates molecular mechanisms linking redox homeostasis to autoimmune pathogenesis. Furthermore, we propose therapeutic strategies that combine redox restoration with the attenuation of aberrant cGAS-STING activation, thereby establishing a mechanistic foundation for precision interventions in autoimmune disorders. METHODS: The manuscript is formatted as a narrative review. We conducted a comprehensive search strategy using electronic databases such as PubMed, Google Scholar and Web of Science. Various keywords were used, such as "cGAS-STING," "Redox homeostasis," "Oxidative stress," "pentose phosphate pathway," "Ferroptosis," "mtDNA," "dsDNA," "DNA damage," "Micronuclei," "Reactive oxygen species," "Reactive nitrogen species," "Nanomaterial," "Autoimmune disease," "Systemic lupus erythematosus," "Type 1 diabetes," "Rheumatoid arthritis," "Multiple sclerosis," "Experimental autoimmune encephalomyelitis," "Psoriasis," etc. The titles and abstracts were reviewed for inclusion into this review. After removing duplicates and irrelevant studies, 174 articles met inclusion criteria (original research, English language).

Antidepressant effect of Radix bupleuri - Radix paeoniae alba herb pair on chronic unpredictable mild stress rats based on cortical metabolomics

OBJECTIVE

Depression is a serious mental disorder, and its incidence rate has increased rapidly. Radix Bupleuri (root of Bupleurum chinensis DC. BR)-Radix Paeoniae Alba (root of Paeonia lactiflora Pall. PRA) herb pair has been historically used for treating depression in Traditional Chinese Medicine (TCM) while the mechanisms need to be fully revealed.

METHODS

The effects of the BR-PRA herb pair were investigated using a rat model of chronic unpredictable mild stress (CUMS). First, the depressive-like behavior of rats was evaluated by open field test (OFT), elevated plus-maze test (EMP), and forced swimming test (FST). Secondly, histomorphological changes in the CA1 and CA3 regions of the hippocampus were analyzed by hematoxylin-eosin, nissl, and Golgi staining. Ultra high-performance liquid chromatograph tandem quadrupole mass spectrometry (UHPLC-QTRAP-MS/MS) was performed to reveal potential antidepressant mechanisms.

RESULTS

Following CUMS exposure, rats displayed depressive-like behavior, and neuronal death in the hippocampal region was observed. Consequently, these abnormal changes were reversed by BR-PRA herb-pair intervention. A total of 26 different metabolites related to depression were identified by metabolomics, mainly involving eleven metabolic pathways of pentose phosphate pathway, purine metabolism, and amino sugar and nucleotide sugar metabolism. BR-PRA herb-pair improved four metabolites, including homocitrulline, N-acetyllysine, corticosterone, and N-acetylglutamate. It also may affect the development of depression by interfering with the hypothalamus-pituitary-adrenal axis (HPA axis), amino acid metabolism related to lysine and glutamate, and modulation of oxidative stress.

CONCLUSION

BR-PRA herb-pair alleviated depressive-like behavior in CUMS rats, recovered hippocampus damage, and regulated cerebral cortex metabolism, which may be related to the HPA axis, amino acid metabolism related to lysine and glutamate, and modulation of oxidative stress.

CLINICAL TRIAL NUMBER

Not applicable.

In vitro modelling of the neuropathophysiological features of mitochondrial epilepsy

Epilepsy is a common and severe neurological manifestation of primary mitochondrial disease, affecting approximately 60 % of paediatric patients and 20 % of adult patients. Many of the mitochondrial epilepsies, particularly those presenting in childhood, are refractory to anti-epileptic treatment. Moreover, these conditions are typically characterised by severe neurodegeneration and closely associated with neurological decline and premature death. Indeed, there persists an urgent need to delineate the mechanisms underpinning mitochondrial epilepsy in order to develop effective treatments. In this review, we provide an overview of currently available in vitro models of the mitochondrial epilepsies. Such models offer opportunities to characterise early disease pathophysiology and interrogate novel mitochondrial-targeting and anti-epileptic treatments, with an overall aim to modulate seizure associated pathology and activity for the mitochondrial epilepsies. We discuss the use of acute cortical and subcortical brain slice preparations, obtained from both neurosurgical patients and rodents, for modelling the common neuropathophysiological features of mitochondrial epilepsy. We also review the use of induced pluripotent stem cell derived neural and glial culture models, and the development of three-dimensional cerebral organoids, generated from fibroblasts obtained from patients with primary mitochondrial disease. Human-derived, disease-relevant in vitro model systems which recapitulate the complexity and pathological features observed in patient brain tissues are crucial to help bridge the gap between animal models and patients living with mitochondrial epilepsy.

Neuropharmacological effects of Gastrodia elata Blume and its active ingredients

Gastrodia elata Blume (GE), a traditional Chinese medicine clinically employed to treat neurological disorders, demonstrates therapeutic efficacy supported by robust clinical evidence. Nowadays, conventional pharmacotherapies for neurological conditions-such as cholinesterase inhibitors for Alzheimer's or Ldopa for Parkinson's-often provide limited symptom relief, exhibit side effects, and fail to halt disease w, underscoring the need for alternative strategies. The primary bioactive compounds of Gastrodia elata Blume (GE) include gastrodin, p-hydroxybenzyl alcohol, Vanillyl alcohol, Polysaccharides, and β-sitosterol. Modern research has demonstrated that GE and its active components exhibit neuropharmacological effects, including neuron protection, reduction of neurotoxicity, and promotion of nerve regeneration and survival. For example, Gastrodin, exerts neuroprotection by scavenging reactive oxygen species, suppressing pro-inflammatory cytokines, and enhancing GABAergic transmission, thereby alleviating oxidative stress and neuronal apoptosis. Vanillin, potentiates GABA receptor activity, enhancing inhibitory neurotransmission and reducing seizure susceptibility.GE polysaccharides modulate the gut-brain axis and suppress microglial activation, mitigating neuroinflammation. Current studies primarily focus on GE and its active ingredients for the treatment of neurological diseases such as Parkinson's disease, Alzheimer's disease, epilepsy, convulsions, depression, schizophrenia, as well as enhancing learning and memory, and preventing or treating cerebral ischemic injury. This review explores the neuropharmacological effects of GE and its active compounds, elucidates the underlying mechanisms, and suggests potential preventive and therapeutic strategies for neurological diseases using herbal remedies.

Advances in research on mitochondrial dysfunction in neurodegenerative diseases

Given the high energy demand of the nervous system, mitochondrial dysfunction is a key factor in the pathogenesis of neurodegenerative diseases. Thus, a comprehensive understanding of its mechanisms and potential therapeutic targets is essential. This review discusses the roles of mitochondrial oxidative stress, mitochondrial dynamics alterations, and mtDNA damage in Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and multiple sclerosis (MS). In addition, it summarizes the contributions of novel technological approaches in detecting mitochondrial dysfunction, which assist in disease diagnosis. We also emphasize emerging therapeutic strategies and drugs aimed at enhancing mitochondrial quality control and reducing oxidative stress, thereby laying the groundwork for innovative therapeutic approaches in neurodegenerative disease treatment.

Differences in Microbial Community Structure Determine the Functional Specialization of Gut Segments of Ligia exotica

Ligia feed on seashore algae and remove organic debris from the coastal zone, thereby playing an important role in the intertidal ecosystem. Nevertheless, the specific roles of distinct gut segments in the gut transit remain unclear. We collected and identified Ligia exotica specimens in the coast of Aoshanwei, Qingdao, Shandong Province, and analyzed their foreguts and hindguts for 16S rRNA, metagenomics, metabolomics, and proteomics. The concentrations of common metabolites, NO3--N and NH4+-N, and the contents of C and N were measured. The gut transit decreased the abundances of the dominant phyla Cyanobacteria but increased Proteobacteria, Firmicutes, and Actinobacteria, and Planctomycetes and Bacteroidetes remained relatively constant. The foregut gut microbiota is involved in the carbohydrates and amino acids metabolism, as well as the decomposition of polysaccharides. The hindgut gut microbiota performs a variety of functions, including carbohydrate and amino acid metabolism, fermentation, cell motility, intracellular transport, secretion, and vesicular translocation, and the decomposition of polysaccharides, disaccharides, and oligosaccharides. The results of omics analyses and molecular experiments demonstrated that the metabolic processes involving amino acids and carbohydrates are more active in the foregut, whereas the fermentation, absorption, and assimilation processes are more active in the hindgut. Taken together, the differences in microbial community structure determine the functional specialization of different gut segments, i.e., the foregut appears to be the primary site for digesting food, while the hindgut further processes and absorbs nutrients and then excretes them.

NOX4 Suppresses Ferroptosis Through Regulation of the Pentose Phosphate Pathway in Colorectal Cancer

OBJECTIVE

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are known as major sources of reactive oxygen species (ROS), yet their role in regulating cellular antioxidative metabolism and ferroptosis is unclear. This study assessed the expression and clinical relevance of NOXs across pan-cancer and investigated the role of NOX4 in colorectal cancer progression METHODS: We analyzed transcriptomic and survival data from The Cancer Genome Atlas (TCGA) for NOXs across 22 types of solid tumors. A CRISPR library targeting NOXs was developed for potential therapeutic target screening in colorectal cancer cells (CRCs). Techniques such as CRISPR-knockout cell lines, 1,2-13C-glucose tracing, PI staining, BrdU assays, and coimmunoprecipitation were employed to elucidate the function of NOX4 in CRCs.

RESULTS

NOX4 emerged as a key therapeutic target for colorectal cancer from TCGA data. CRISPR screening highlighted its essential role in CRC survival, with functional experiments confirming that NOX4 upregulation promotes cell survival and proliferation. The interaction of NOX4 with glucose‑6‑phosphate dehydrogenase (G6PD) was found to enhance the pentose phosphate pathway (PPP), facilitating ROS clearance and protecting CRCs against ferroptosis.

CONCLUSIONS

This study identified NOX4 as a novel ferroptosis suppressor and a therapeutic target for the treatment of colorectal cancer. The findings suggest that a coupling between NADPH oxidase enzyme NOX4 and the PPP regulates ferroptosis and reveal an accompanying metabolic vulnerability for therapeutic targeting in colorectal cancer.

Metabolomics in Parkinson's Disease and Correlation with Disease State

Changes in the level of metabolites, small molecules that are intermediates produced by metabolism or catabolism, are associated with developing diseases. Metabolite signatures in body fluids such as plasma, cerebrospinal fluid, urine, and saliva are associated with Parkinson's disease. Here, we discuss alteration of metabolites in the TCA cycle, pentose phosphate pathway, kynurenic network, and redox system. We also summarize the efforts of many research groups to differentiate between metabolite profiles that characterize PD motor progression and dyskinesia, gait and balance, and non-motor symptoms such as depression and cognitive decline. Understanding how changes in metabolites lead to progression in PD may allow for the identification of individuals at the earliest stage of the disease and the development of new therapeutic strategies.

Metabolic Atlas of Early Human Cortex Identifies Regulators of Cell Fate Transitions

Characterization of cell type emergence during human cortical development, which enables unique human cognition, has focused primarily on anatomical and transcriptional characterizations. Metabolic processes in the human brain that allow for rapid expansion, but contribute to vulnerability to neurodevelopmental disorders, remain largely unexplored. We performed a variety of metabolic assays in primary tissue and stem cell derived cortical organoids and observed dynamic changes in core metabolic functions, including an unexpected increase in glycolysis during late neurogenesis. By depleting glucose levels in cortical organoids, we increased outer radial glia, astrocytes, and inhibitory neurons. We found the pentose phosphate pathway (PPP) was impacted in these experiments and leveraged pharmacological and genetic manipulations to recapitulate these radial glia cell fate changes. These data identify a new role for the PPP in modulating radial glia cell fate specification and generate a resource for future exploration of additional metabolic pathways in human cortical development.

Inflammation and metabolic dysfunction underly anhedonia-like behavior in antidepressant resistant male rats

Inflammation and metabolic dysfunction impair dopamine neurotransmission, which is thought to serve as a critical mechanism underpinning motivational deficits such as anhedonia across a range of psychiatric and neurological disorders. This difficult-to-treat transdiagnostic symptom has important implications for treatment resistant depression (TRD), and may warrant more targeted therapeutic approaches that address the underlying pathophysiological mechanisms. Using the adrenocorticotrophic hormone (ACTH) model of antidepressant treatment resistance we characterized the relationship between antidepressant-like and anhedonia-like behavioral responses to bupropion, mesocortical tyrosine hydroxylase (TH) expression, chronic low-grade inflammation, and metabolic changes in male rats. We demonstrate that chronic ACTH elicited both an antidepressant resistant- and anhedonia-like phenotype in forced swim and effort-related choice behavioral tasks, respectively. This was associated with decreased TH expression in the brain, increased central and peripheral markers of inflammation, and peripheral metabolic disturbances, including impairment of immune cell insulin action. Multivariate analysis revealed that peripheral interleukin-6 (IL-6) levels, immune cell glucose uptake and disturbance of nucleotide metabolism were strongly associated with anhedonia-like behavior. Post-hoc analyses further confirmed strong correlations between TH expression, inflammation and behavioral performance. These data suggest that stress hormone-induced upregulation of inflammation concurrent with the impairment of insulin-mediated glucose uptake into immune cells is associated with disruption of nucleotide metabolism, and potential impaired central dopamine synthesis contributing to the behavioral expression of anhedonia. These results suggest that immunometabolic perturbations concomitant with impaired insulin action at the level of the immune cell result in a metabolically deficient state that directly impacts nucleotide precursors essential for dopamine synthesis and effortful behavior. These results highlight the potential for immune and metabolic markers for individualized treatment of refractory depression and anhedonia.

Glucose Metabolic Reprogramming in Microglia: Implications for Neurodegenerative Diseases and Targeted Therapy

As intrinsic immune cells in the central nervous system, microglia play a crucial role in maintaining brain homeostasis. Microglia can transition from homeostasis to various responsive states in reaction to different external stimuli, undergoing corresponding alterations in glucose metabolism. In neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), microglial glucose metabolic reprogramming is widespread. This reprogramming leads to changes in microglial function, exacerbating neuroinflammation and the accumulation of pathological products, thereby driving the progression of neurodegeneration. This review summarizes the specific alterations in glucose metabolism within microglia in AD, PD, ALS, and MS, as well as the corresponding treatments aimed at reprogramming glucose metabolism. Compounds that inhibit key glycolytic enzymes like hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2), or activate regulators of energy metabolism such as AMP-activated protein kinase (AMPK), have shown significant potential in the treatment of various neurodegenerative diseases. However, current research faces numerous challenges, including side effects and blood-brain barrier (BBB) penetration of compounds. Screening relevant drugs from natural products, especially flavonoids, is a reliable approach. On the one hand, longtime herbal medical practices provide a certain degree of assurance regarding clinical safety, and their chemical properties contribute to effective BBB permeability. On the other hand, the concurrent anti-tumor and anti-neuroinflammatory activities of flavonoids suggest that regulation of glucose metabolism reprogramming might be a potential common mechanism of action. Notably, considering the dynamic nature of microglial metabolism, there is an urgent need to develop technologies for real-time monitoring of glucose metabolism processes, which would significantly advance research in this field.

Apelin-13 attenuates optic nerve damage in glaucomatous mice by regulating glucose metabolism

BACKGROUND

In patients with advanced glaucoma, lesions frequently extend beyond the eye and affect other organs. However, early distal consequences of elevated intraocular pressure (IOP) remain unclear. This study aimed to observe glucose uptake in the optic cortex during the early stages of elevated IOP and to investigate the mechanism by which Apelin13 exerts neuroprotective effects.

METHODS

This study used a single anterior chamber injection of polystyrene microbeads and triblock copolymer hydrogel in 6- to 8-week-old male C57BL/6J mice and observed glucose uptake in the optic cortex during the initial phase of IOP elevation using micro-positron emission tomography/magnetic resonance imaging (PET/MRI). Pathological changes in the optic nerve and optic cortex were assessed by immunofluorescence, reactive oxygen species (ROS) kit, and and nicotinamide adenine dinucleotide phosphate (NADPH) kit. Expression of glucose transporter proteins (GLUTs) and key enzymes of the pentose phosphate pathway (PPP) was evaluated using immunofluorescence and western blot. The activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B signaling pathway was analyzed via western blot.

RESULTS

On day 1 of elevated IOP, the modeled eye exhibited reduced glucose uptake in the corresponding visual cortex compared with the contralateral visual cortex. Over time, the condition gradually improved, with no discernible difference between the two sides by day 21. Concurrently, along with abnormal activation of microglia and progressive reduction of retinal ganglion cells, we noted abnormal expression of glucose transporter proteins in visual cortical neurons. Additionally, elevated levels of ROS and NADPH were observed in both the retinal and brain tissues following IOP elevation. In contrast, administration of the neuroprotectant Apelin-13 mitigated the pathology induced by IOP elevation. Conversely, treatment with a PI3K inhibitor significantly diminished the protective effects of Apelin-13.

CONCLUSIONS

These findings imply that altered glucose metabolism in the visual center may be an early sign of optic nerve damage in patients with glaucoma. Apelin-13 may rely on the PI3K/Akt signaling pathway to regulate the redistribution of energy metabolism in the retina and visual centers, thereby mitigating oxidative stress and safeguarding neuronal cells.

Parkinson's disease and glucose metabolism impairment

Parkinson's disease (PD) is the second most common neurodegenerative disorder. PD patients exhibit varying degrees of abnormal glucose metabolism throughout disease stages. Abnormal glucose metabolism is closely linked to the PD pathogenesis and progression. Key glucose metabolism processes involved in PD include glucose transport, glycolysis, the tricarboxylic acid cycle, oxidative phosphorylation, the pentose phosphate pathway, and gluconeogenesis. Recent studies suggest that glucose metabolism is a potential therapeutic target for PD. In this review, we explore the connection between PD and abnormal glucose metabolism, focusing on the underlying pathophysiological mechanisms. We also summarize potential therapeutic drugs related to glucose metabolism based on results from current cellular and animal model studies.

Brain network and energy imbalance in Parkinson's disease: linking ATP reduction and α-synuclein pathology

Parkinson's disease (PD) involves the disruption of brain energy homeostasis. This encompasses broad-impact factors such as mitochondrial dysfunction, impaired glycolysis, and other metabolic disturbances, like disruptions in the pentose phosphate pathway and purine metabolism. Cortical hubs, which are highly connected regions essential for coordinating multiple brain functions, require significant energy due to their dense synaptic activity and long-range connections. Deficits in ATP production in PD can severely impair these hubs. The energy imbalance also affects subcortical regions, including the massive axonal arbors in the striatum of substantia nigra pars compacta neurons, due to their high metabolic demand. This ATP decline may result in α-synuclein accumulation, autophagy-lysosomal system impairment, neuronal network breakdown and accelerated neurodegeneration. We propose an "ATP Supply-Demand Mismatch Model" to help explain the pathogenesis of PD. This model emphasizes how ATP deficits drive pathological protein aggregation, impaired autophagy, and the degeneration of key brain networks, contributing to both motor and non-motor symptoms.

Reciprocal interactions between glioma and tissue-resident cells fueling tumor progression

Gliomas are the most frequent primary brain tumor and are essentially incurable. While nondiffuse gliomas are circumscribed, diffuse gliomas display an aggressive behavior characterized by tumor cell migration over large distances into the brain parenchyma, thereby precluding curative surgical resection. Almost all diffuse gliomas progress and recur as higher grades and become resistant to standard-of-care treatments. It is being increasingly recognized that glioma cells establish functional interactions with cells residing in the tumor microenvironment. Of these, tumor-associated microglia and macrophages (TAMs) play critical roles in immunosuppression through modulation of the extracellular matrix, and the secretion of molecules such as cytokines, neurotrophic factors, and micro-RNAs (miRNAs). Conversely, glioma cell signals influence cell states and drive the metabolic reprogramming of TAMs. Similarly, emergent evidence indicates that neuronal activity influences glioma by released factors and by establishing functional synapses with glioma cells to promote tumor growth and invasion. Glioma cells also affect local neuronal activities and maintain connections through microtube gap junctions to amplify local effects. Here, we discuss the molecular mechanisms underlying bidirectional interactions between glioma cells and TAMs, as well as between glioma cells and neurons. A better understanding of these cellular cross talks is crucial for the development of novel therapeutic strategies for diffuse gliomas.

Insulin resistance compromises midbrain organoid neuronal activity and metabolic efficiency predisposing to Parkinson's disease pathology

Growing evidence indicates that type 2 diabetes (T2D) is associated with an increased risk of developing Parkinson's disease (PD) through shared disease mechanisms. Studies show that insulin resistance, which is the driving pathophysiological mechanism of T2D plays a major role in neurodegeneration by impairing neuronal functionality, metabolism and survival. To investigate insulin resistance caused pathological changes in the human midbrain, which could predispose a healthy midbrain to PD development, we exposed iPSC-derived human midbrain organoids from healthy individuals to either high insulin concentration, promoting insulin resistance, or to more physiological insulin concentration restoring insulin signalling function. We combined experimental methods with metabolic modelling to identify the most insulin resistance-dependent pathogenic processes. We demonstrate that insulin resistance compromises organoid metabolic efficiency, leading to increased levels of oxidative stress. Additionally, insulin-resistant midbrain organoids showed decreased neuronal activity and reduced amount of dopaminergic neurons, highlighting insulin resistance as a significant target in PD prevention.

Hidden role of microglia during neurodegenerative disorders and neurocritical care: A mitochondrial perspective

The incidence of aging-related neurodegenerative disorders and neurocritical care diseases is increasing worldwide. Microglia, the main inflammatory cells in the brain, could be potential viable therapeutic targets for treating neurological diseases. Interestingly, mitochondrial functions, including energy metabolism, mitophagy and transfer, fission and fusion, and mitochondrial DNA expression, also change in activated microglia. Notably, mitochondria play an active and important role in the pathophysiology of neurodegenerative disorders and neurocritical care diseases. This review briefly summarizes the current knowledge on mitochondrial dysfunction in microglia in neurodegenerative disorders and neurocritical care diseases and comprehensively discusses the prospects of the application of neurological injury prevention and treatment targets by mitochondria.

Identification of the serum metabolomic profile for acute ischemic preconditioning in athletes

Purpose

In recent years, ischemic preconditioning (IPC) has emerged as an effective strategy to increase tissue resistance against long-term ischemic damage and has been increasingly integrated into exercise regimens. However, further research is needed to explore the impact of IPC-mediated metabolic alterations from an exercise standpoint to conduct a comprehensive exploration of metabolic alterations and their exercise-related mechanisms during acute IPC.

Methods

Nontarget metabolomics was performed on blood samples obtained from 8 male athletes both before and after IPC. The studies included the identification of differentially abundant metabolites, analysis of receiver operating characteristic (ROC) curves, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis for differentially abundant metabolites, and metabolite set enrichment analysis (MSEA).

Results

Nineteen differentially abundant metabolites were identified, with increasing levels of five metabolites, such as O-desmethyltramadol and D-gluconate, whereas 14 metabolites, including 9-hydroxy-10e, 12z-octadecadienoic acid (9-HODE), tetradione, 2-hexenal, (2,4-dichlorophenoxy)acetic acid (2,4-D), and phosphatidylserine (PS), decreased. ROC curve analysis revealed an AUC of 0.9375 for D-gluconate. Both KEGG enrichment analysis and MSEA revealed enrichment in the pentose phosphate pathway (PPP).

Conclusion

This study revealed that PPP, D-gluconate, O-desmethyltramadol, and D-2-aminobutyric acid could be upregulated within 5 min after acute IPC, whereas 2,4-D, PS, 9-HODE, 2-hexenal, and tetradinone could be downregulated. These identified metabolites show promise for improving physical functional status and could be harnessed to enhance athletic performance.

Unique tau- and synuclein-dependent metabolic reprogramming in neurons distinct from normal aging

Neuronal cells are highly specialized cells and have a specific metabolic profile to support their function. It has been demonstrated that the metabolic profiles of different cells/tissues undergo significant reprogramming with advancing age, which has often been considered a contributing factor towards aging-related diseases including Alzheimer's (AD) and Parkinson's (PD) diseases. However, it is unclear if the metabolic changes associated with normal aging predispose neurons to disease conditions or a distinct set of metabolic alterations happen in neurons in AD or PD which might contribute to disease pathologies. To decipher the changes in neuronal metabolism with age, in AD, or in PD, we performed high-throughput steady-state metabolite profiling on heads in wildtype Drosophila and in Drosophila models relevant to AD and PD. Intriguingly, we found that the spectrum of affected metabolic pathways is dramatically different between normal aging, Tau, or Synuclein overexpressing neurons. Genetic targeting of the purine and glutamate metabolism pathways, which were dysregulated in both old age and disease conditions partially rescued the neurodegenerative phenotype associated with the overexpression of wildtype and mutant tau. Our findings support a "two-hit model" to explain the pathological manifestations associated with AD where both aging- and Tau/Synuclein- driven metabolic reprogramming events cooperate with each other, and targeting both could be a potent therapeutic strategy.

MicroRNAs as Biomarkers in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a severe neurodegenerative disease caused by the loss of the survival motor neuron (SMN) protein, leading to degeneration of anterior motor neurons and resulting in progressive muscle weakness and atrophy. Given that SMA has a single, well-defined genetic cause, gene-targeted therapies have been developed, aiming to increase SMN production in SMA patients. The SMN protein is likely involved in the synthesis of microRNAs (miRNAs), and dysregulated miRNA expression is increasingly associated with the pathophysiology of SMA. Currently, there is a lack of reliable biomarkers to monitor SMA; therefore, the search for novel SMA biomarkers, including miRNAs, is crucial as reliable tools are needed to track disease progression, predict the response to therapy and understand the different clinical outcomes of available treatments. In this review, we compile data on miRNAs associated with SMA pathogenesis and their potential use as biomarkers. Based on current knowledge, the most frequently deregulated miRNAs between SMA patients and controls, as well as pre- and post-treatment in SMA patients, include miR-1-3p, miR-133a-3p, miR-133b, and miR-206. These findings offer promising possibilities for improving patient classification and monitoring disease progression and response to treatment. Additionally, these findings provide insights into the broader molecular mechanisms and networks of SMA that could inform the development of future therapeutic strategies.

PFKFB3 ameliorates ischemia-induced neuronal damage by reducing reactive oxygen species and inhibiting nuclear translocation of Cdk5

The enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB) plays an essential role in glycolysis and in the antioxidant pathway associated with glutathione. Therefore, we investigated the effects of PFKFB3 on oxidative and ischemic damage. We synthesized a fusion protein of transactivator of transcription (Tat)-PFKFB3 to facilitate its passage into the intracellular space and examine its effects against oxidative stress induced by hydrogen peroxide (H2O2) treatment and ischemic damage caused by occlusion of the common carotid arteries for 5 min in gerbils. The Tat-PFKFB3 protein was efficiently delivered into HT22 cells in a concentration- and time-dependent manner, with higher levels observed 18 h after treatment. Furthermore, treatment with 6 µM Tat-PFKFB3 demonstrated intracellular delivery into HT22 cells, as analyzed through immunocytochemical staining. Moreover, it significantly ameliorated the reduction of cell viability induced by 200 µM H2O2 treatment. Tat-PFKFB3 treatment also alleviated H2O2-induced DNA fragmentation and reactive oxygen species formation in HT22 cells. In gerbils, the intraperitoneal administration of 2 mg/kg Tat-PFKFB3 efficiently delivered the substance to all hippocampal areas, including the hippocampal CA1 region. This administration significantly mitigated ischemia-induced hyperlocomotion, long-term memory deficits, and ischemic neuronal death in the hippocampal CA1 region after ischemia. Additionally, treatment with 2 mg/kg Tat-PFKFB3 significantly ameliorated the translocation of Cdk5 from the cytosol to the nucleus in the hippocampal CA1 region 24 h after ischemia, but not in other regions. The treatment also significantly reduced reactive oxygen species formation in the CA1 region. These findings suggest that Tat-PFKFB3 reduces neuronal damage in the hippocampal CA1 region after ischemia through the reduction of Cdk5 signaling and reactive oxygen species formation. Therefore, Tat-PFKFB3 may have potential applications in reducing ischemic damage.

The mitochondrial translocator protein (TSPO) in Alzheimer's disease: Therapeutic and immunomodulatory functions

The translocator protein (TSPO) has been widely investigated as a PET-imaging biomarker of neuroinflammation and, more recently, as a therapeutic target for the treatment of neurodegenerative disease. TSPO ligands have been shown to exert neuroprotective effects in vivo and in vitro models of Alzheimer's disease (AD), by reducing toxic beta amyloid peptides, and attenuating brain atrophy. Recent transcriptomic and proteomic analyses, and the generation of TSPO-KO mice, have enabled new insights into the mechanistic function of TSPO in AD. Using a multi-omics approach in both TSPO-KO- and TSPO ligand-treated mice, we have demonstrated a key role for TSPO in microglial respiratory metabolism and phagocytosis in AD. In this review, we discuss emerging evidence for therapeutic and immunomodulatory functions of TSPO in AD, and new tools for studying TSPO in the brain.

The Anticancer Activity of Monosaccharides: Perspectives and Outlooks

A major hallmark of cancer is the reprogramming of cellular metabolism from oxidative phosphorylation (OXPHOS) to glycolysis, a phenomenon known as the Warburg effect. To sustain high rates of glycolysis, cancer cells overexpress GLUT transporters and glycolytic enzymes, allowing for the enhanced uptake and consumption of glucose. The Warburg effect may be exploited in the treatment of cancer; certain epimers and derivatives of glucose can enter cancer cells and inhibit glycolytic enzymes, stunting metabolism and causing cell death. These include common dietary monosaccharides (ᴅ-mannose, ᴅ-galactose, ᴅ-glucosamine, ʟ-fucose), as well as some rare monosaccharides (xylitol, ᴅ-allose, ʟ-sorbose, ʟ-rhamnose). This article reviews the literature on these sugars in in vitro and in vivo models of cancer, discussing their mechanisms of cytotoxicity. In addition to this, the anticancer potential of some synthetically modified monosaccharides, such as 2-deoxy-ᴅ-glucose and its acetylated and halogenated derivatives, is reviewed. Further, this article reviews how certain monosaccharides can be used in combination with anticancer drugs to potentiate conventional chemotherapies and to help overcome chemoresistance. Finally, the limitations of administering two separate agents, a sugar and a chemotherapeutic drug, are discussed. The potential of the glycoconjugation of classical or repurposed chemotherapy drugs as a solution to these limitations is reviewed.

Significance and amplification methods of the purine salvage pathway in human brain cells

Previous studies suggest that uric acid or reactive oxygen species, products of xanthine oxidoreductase (XOR), may associate with neurodegenerative diseases. However, neither relationship has ever been firmly established. Here, we analyzed human brain samples, obtained under protocols approved by research ethics committees, and found no expression of XOR and only low levels of uric acid in various regions of the brain. In the absence of XOR, hypoxanthine will be preserved and available for incorporation into the purine salvage pathway. To clarify the importance of salvage in the brain, we tested using human-induced pluripotent stem cell-derived neuronal cells. Stable isotope analyses showed that the purine salvage pathway was more effective for ATP synthesis than purine de novo synthesis. Blood uric acid levels were related to the intracellular adenylate pool (ATP + ADP + AMP), and reduced levels of this pool result in lower uric acid levels. XOR inhibitors are related to extracellular hypoxanthine levels available for uptake into the purine salvage pathway by inhibiting the oxidation of hypoxanthine to xanthine and uric acid in various organs where XOR is present and can prevent further decreases in the intracellular adenylate pool under stress. Furthermore, adding precursors of the pentose phosphate pathway enhanced hypoxanthine uptake, indicating that purine salvage is activated by phosphoribosyl pyrophosphate replenishment. These findings resolve previous contradictions regarding XOR products and provide new insights into clinical studies. It is suggested that therapeutic strategies maximizing maintenance of intracellular adenylate levels may effectively treat pathological conditions associated with ischemia and energy depletion.

Integrated Multi-Omics Analysis of Cerebrospinal Fluid in Postoperative Delirium

Preoperative risk biomarkers for delirium may aid in identifying high-risk patients and developing intervention therapies, which would minimize the health and economic burden of postoperative delirium. Previous studies have typically used single omics approaches to identify such biomarkers. Preoperative cerebrospinal fluid (CSF) from the Healthier Postoperative Recovery study of adults ≥ 63 years old undergoing elective major orthopedic surgery was used in a matched pair delirium case-no delirium control design. We performed metabolomics and lipidomics, which were combined with our previously reported proteomics results on the same samples. Differential expression, clustering, classification, and systems biology analyses were applied to individual and combined omics datasets. Probabilistic graph models were used to identify an integrated multi-omics interaction network, which included clusters of heterogeneous omics interactions among lipids, metabolites, and proteins. The combined multi-omics signature of 25 molecules attained an AUC of 0.96 [95% CI: 0.85-1.00], showing improvement over individual omics-based classification. We conclude that multi-omics integration of preoperative CSF identifies potential risk markers for delirium and generates new insights into the complex pathways associated with delirium. With future validation, this hypotheses-generating study may serve to build robust biomarkers for delirium and improve our understanding of its pathophysiology.

Renal inflammation combined with renal function reserve reduction accelerate kidney aging via pentose phosphate pathway

Aging is closely associated with inflammation, which affects renal function reserve (RFR) in the kidneys. This study aims to investigate the impact of reduced RFR reduction on kidney aging and the influence of renal inflammation and RFR reduction on this process. Natural aging rats and those subjected to unilateral nephrectomy (UNX), 1/6 nephrectomy (1/6NX), and unilateral ureteral obstruction (UUO) were observed at 6, 12, 18, and 21 months. Our findings suggest that RFR reduction and renal inflammation can accelerate kidney aging, and inflammation contributes more. Metabolomics analysis revealed alterations in amino acid metabolism contribute to RFR decline. Furthermore, experiments in vitro confirmed the involvement of pentose phosphate pathway (PPP) in promoting aging though inflammation. Our research provides novel insights into for the mechanism of kidney aging and provides indirect support for clinical treatment decisions, such as addressing kidney inflammation, stones, or tumors that may necessitate partial or complete nephrectomy.

Glycometabolic Reprogramming of Microglia in Neurodegenerative Diseases: Insights from Neuroinflammation

Neurodegenerative diseases (ND) are conditions defined by progressive deterioration of the structure and function of the nervous system. Some major examples include Alzheimer's disease (AD), Parkinson's disease (PD), and Amyotrophic lateral sclerosis (ALS). These diseases lead to various dysfunctions, like impaired cognition, memory, and movement. Chronic neuroinflammation may underlie numerous neurodegenerative disorders. Microglia, an important immunocell in the brain, plays a vital role in defending against neuroinflammation. When exposed to different stimuli, microglia are activated and assume different phenotypes, participating in immune regulation of the nervous system and maintaining tissue homeostasis. The immunological activity of activated microglia is affected by glucose metabolic alterations. However, in the context of chronic neuroinflammation, specific alterations of microglial glucose metabolism and their mechanisms of action remain unclear. Thus, in this paper, we review the glycometabolic reprogramming of microglia in ND. The key molecular targets and main metabolic pathways are the focus of this research. Additionally, this study explores the mechanisms underlying microglial glucose metabolism reprogramming in ND and offers an analysis of the most recent therapeutic advancements. The ultimate aim is to provide insights into the development of potential treatments for ND.

The Contribution of Type 2 Diabetes to Parkinson's Disease Aetiology

Type 2 diabetes (T2D) and Parkinson's disease (PD) are chronic disorders that have a significant health impact on a global scale. Epidemiological, preclinical, and clinical research underpins the assumption that insulin resistance and chronic inflammation contribute to the overlapping aetiologies of T2D and PD. This narrative review summarises the recent evidence on the contribution of T2D to the initiation and progression of PD brain pathology. It also briefly discusses the rationale and potential of alternative pharmacological interventions for PD treatment.

Fructose overconsumption-induced reprogramming of microglia metabolism and function

The overconsumption of dietary fructose has been proposed as a major culprit for the rise of many metabolic diseases in recent years, yet the relationship between a high fructose diet and neurological dysfunction remains to be explored. Although fructose metabolism mainly takes place in the liver and intestine, recent studies have shown that a hyperglycemic condition could induce fructose metabolism in the brain. Notably, microglia, which are tissue-resident macrophages (Mφs) that confer innate immunity in the brain, also express fructose transporters (GLUT5) and are capable of utilizing fructose as a carbon fuel. Together, these studies suggest the possibility that a high fructose diet can regulate the activation and inflammatory response of microglia by metabolic reprogramming, thereby altering the susceptibility of developing neurological dysfunction. In this review, the recent advances in the understanding of microglia metabolism and how it supports its functions will be summarized. The results from both in vivo and in vitro studies that have investigated the mechanistic link between fructose-induced metabolic reprogramming of microglia and its function will then be reviewed. Finally, areas of controversies and their associated implications, as well as directions that warrant future research will be highlighted.

Parkinson's disease-derived α-synuclein assemblies combined with chronic-type inflammatory cues promote a neurotoxic microglial phenotype

Parkinson's disease (PD) is a common age-related neurodegenerative disorder characterized by the aggregation of α-Synuclein (αSYN) building up intraneuronal inclusions termed Lewy pathology. Mounting evidence suggests that neuron-released αSYN aggregates could be central to microglial activation, which in turn mounts and orchestrates neuroinflammatory processes potentially harmful to neurons. Therefore, understanding the mechanisms that drive microglial cell activation, polarization and function in PD might have important therapeutic implications. Here, using primary microglia, we investigated the inflammatory potential of pure αSYN fibrils derived from PD patients. We further explored and characterized microglial cell responses to a chronic-type inflammatory stimulation combining PD patient-derived αSYN fibrils (FPD), Tumor necrosis factor-α (TNFα) and prostaglandin E2 (PGE2) (TPFPD). We showed that FPD hold stronger inflammatory potency than pure αSYN fibrils generated de novo. When combined with TNFα and PGE2, FPD polarizes microglia toward a particular functional phenotype departing from FPD-treated cells and featuring lower inflammatory cytokine and higher glutamate release. Whereas metabolomic studies showed that TPFPD-exposed microglia were closely related to classically activated M1 proinflammatory cells, notably with similar tricarboxylic acid cycle disruption, transcriptomic analysis revealed that TPFPD-activated microglia assume a unique molecular signature highlighting upregulation of genes involved in glutathione and iron metabolisms. In particular, TPFPD-specific upregulation of Slc7a11 (which encodes the cystine-glutamate antiporter xCT) was consistent with the increased glutamate response and cytotoxic activity of these cells toward midbrain dopaminergic neurons in vitro. Together, these data further extend the structure-pathological relationship of αSYN fibrillar polymorphs to their innate immune properties and demonstrate that PD-derived αSYN fibrils, TNFα and PGE2 act in concert to drive microglial cell activation toward a specific and highly neurotoxic chronic-type inflammatory phenotype characterized by robust glutamate release and iron retention.

Glucose-6-Phosphatase-Dehydrogenase activity as modulative association between Parkinson's disease and periodontitis

The association between periodontitis (PD) and Parkinson's disease (PK) is discussed due to the inflammatory component of neurodegenerative processes. PK severity and affected areas were determined using the following neuropsychological tests: Unified Parkinson's Disease Rating Score (UPDRS) and Hoehn and Yahr; non-motoric symptoms by Non-Motor Symptoms Scale (NMSS), and cognitive involvement by Mini-Mental State Examination (MMSE). Neuroinflammation and the resulting Glucose-6-Phosphatase-Dehydrogenase (G6PD) dysfunction are part of the pathophysiology of PK. This study aimed to evaluate these associations in periodontal inflammation. Clinical data and saliva-, serum-, and RNA-biobank samples of 50 well-characterized diametric patients with PK and five age- and sex-matched neurologically healthy participants were analyzed for G6PD function, periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia, Campylobacter rectus, Fusobacterium nucleatum, and Filifactor alocis), monocyte chemoattractant protein (MCP) 1, and interleukin (IL) 1-beta. Regression analysis was used to identify associations between clinical and behavioral data, and t-tests were used to compare health and disease. Compared with PK, no pathogens and lower inflammatory markers (p < 0.001) were detectible in healthy saliva and serum, PK-severity/UPDRS interrelated with the occurrence of Prevotella intermedia in serum as well as IL1-beta levels in serum and saliva (p = 0.006, 0.019, 0.034), Hoehn and Yahr correlated with Porphyromonas gingivalis, Prevotella intermedia, RNA IL1-beta regulation, serum, and saliva IL1-beta levels, with p-values of 0.038, 0.011, 0.008, <0.001, and 0.010, while MMSE was associated with Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, serum MCP 1 levels, RNA IL1-beta regulation and G6PD serum activity (p = 0.036, 0.003, 0.045, <0.001, and 0.021). Cognitive and motor skills seem to be important as representative tests are associated with periodontal pathogens and oral/general inflammation, wherein G6PD-saliva dysfunction might be involved.

Clinical trial registration

https://www.bfarm.de/DE/Das-BfArM/Aufgaben/Deutsches-Register-Klinischer-Studien/_node.html, identifier DRKS00005388.

The potential role of glucose metabolism, lipid metabolism, and amino acid metabolism in the treatment of Parkinson's disease

PURPOSE OF REVIEW

Parkinson's disease (PD) is a common neurodegenerative disease, which can cause progressive deterioration of motor function causing muscle stiffness, tremor, and bradykinesia. In this review, we hope to describe approaches that can improve the life of PD patients through modifications of energy metabolism.

RECENT FINDINGS

The main pathological features of PD are the progressive loss of nigrostriatal dopaminergic neurons and the production of Lewy bodies. Abnormal aggregation of α-synuclein (α-Syn) leading to the formation of Lewy bodies is closely associated with neuronal dysfunction and degeneration. The main causes of PD are said to be mitochondrial damage, oxidative stress, inflammation, and abnormal protein aggregation. Presence of abnormal energy metabolism is another cause of PD. Many studies have found significant differences between neurodegenerative diseases and metabolic decompensation, which has become a biological hallmark of neurodegenerative diseases.

SUMMARY

In this review, we highlight the relationship between abnormal energy metabolism (Glucose metabolism, lipid metabolism, and amino acid metabolism) and PD. Improvement of key molecules in glucose metabolism, fat metabolism, and amino acid metabolism (e.g., glucose-6-phosphate dehydrogenase, triglycerides, and levodopa) might be potentially beneficial in PD. Some of these metabolic indicators may serve well during the diagnosis of PD. In addition, modulation of these metabolic pathways may be a potential target for the treatment and prevention of PD.

Newborn screening for G6PD deficiency in HeFei, FuYang and AnQing, China: Prevalence, cut-off value, variant spectrum

Background

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive Mendelian genetic disorder characterized by neonatal jaundice and hemolytic anemia, affecting more than 400 million people worldwide. The purpose of this research was to investigate prevalence rates of G6PD deficiency and to evaluate and establish specific cut-off values in early prediction of G6PD deficiency by regions (HeFei, FuYang, AnQing) on different seasons, as well as to investigate the frequencies of G6PD gene mutations among three regions mentioned above.

Methods

A total of 31,482 neonates (21,402, 7680, and 2340 for HeFei, FuYang, and AnQing cities, respectively) were recruited. Positive subjects were recalled to attend genetic tests for diagnosis. G6PD activity on the Genetic screening processor (GSP analyzer, 2021-0010) was measured following the manufactureržs protocol. The cut-off value was first set to 35 U/dL. The receiver operating characteristics (ROC) curve was employed to assess and compare the efficiency in predicting G6PD deficiency among HeFei, FuYang, and AnQing cities in different seasons.

Metabolic Reprogramming in Gliocyte Post-cerebral Ischemia/ Reperfusion: From Pathophysiology to Therapeutic Potential

Ischemic stroke is a leading cause of disability and death worldwide. However, the clinical efficacy of recanalization therapy as a preferred option is significantly hindered by reperfusion injury. The transformation between different phenotypes of gliocytes is closely associated with cerebral ischemia/ reperfusion injury (CI/RI). Moreover, gliocyte polarization induces metabolic reprogramming, which refers to the shift in gliocyte phenotype and the overall transformation of the metabolic network to compensate for energy demand and building block requirements during CI/RI caused by hypoxia, energy deficiency, and oxidative stress. Within microglia, the pro-inflammatory phenotype exhibits upregulated glycolysis, pentose phosphate pathway, fatty acid synthesis, and glutamine synthesis, whereas the anti-inflammatory phenotype demonstrates enhanced mitochondrial oxidative phosphorylation and fatty acid oxidation. Reactive astrocytes display increased glycolysis but impaired glycogenolysis and reduced glutamate uptake after CI/RI. There is mounting evidence suggesting that manipulation of energy metabolism homeostasis can induce microglial cells and astrocytes to switch from neurotoxic to neuroprotective phenotypes. A comprehensive understanding of underlying mechanisms and manipulation strategies targeting metabolic pathways could potentially enable gliocytes to be reprogrammed toward beneficial functions while opening new therapeutic avenues for CI/RI treatment. This review provides an overview of current insights into metabolic reprogramming mechanisms in microglia and astrocytes within the pathophysiological context of CI/RI, along with potential pharmacological targets. Herein, we emphasize the potential of metabolic reprogramming of gliocytes as a therapeutic target for CI/RI and aim to offer a novel perspective in the treatment of CI/RI.

Extracellular vesicles from hiPSC-NSCs can prevent peripheral inflammation-induced cognitive dysfunction with inflammasome inhibition and improved neurogenesis in the hippocampus

Extracellular vesicles (EVs) released by human induced pluripotent stem cell-derived neural stem cells (hiPSC-NSCs) are enriched with miRNAs and proteins capable of mediating robust antiinflammatory activity. The lack of tumorigenic and immunogenic properties and ability to permeate the entire brain to incorporate into microglia following intranasal (IN) administrations makes them an attractive biologic for curtailing chronic neuroinflammation in neurodegenerative disorders. We tested the hypothesis that IN administrations of hiPSC-NSC-EVs can alleviate chronic neuroinflammation and cognitive impairments induced by the peripheral lipopolysaccharide (LPS) challenge. Adult male, C57BL/6J mice received intraperitoneal injections of LPS (0.75 mg/kg) for seven consecutive days. Then, the mice received either vehicle (VEH) or hiPSC-NSC-EVs (~ 10 × 109 EVs/administration, thrice over 6 days). A month later, mice in all groups were investigated for cognitive function with behavioral tests and euthanized for histological and biochemical studies. Mice receiving VEH after LPS displayed deficits in associative recognition memory, temporal pattern processing, and pattern separation. Such impairments were associated with an increased incidence of activated microglia presenting NOD-, LRR-, and pyrin domain containing 3 (NLRP3) inflammasomes, elevated levels of NLRP3 inflammasome mediators and end products, and decreased neurogenesis in the hippocampus. In contrast, the various cognitive measures in mice receiving hiPSC-NSC-EVs after LPS were closer to naive mice. Significantly, these mice displayed diminished microglial activation, NLRP3 inflammasomes, proinflammatory cytokines, and a level of neurogenesis matching age-matched naïve controls. Thus, IN administrations of hiPSC-NSC-EVs are an efficacious approach to reducing chronic neuroinflammation-induced cognitive impairments.

The NADPH Link between the Renin Angiotensin System and the Antioxidant Mechanisms in Dopaminergic Neurons

The renin angiotensin system (RAS) has several components including signaling peptides, enzymes, and membrane receptors. The effort in characterizing this system in the periphery has led to the approval of a class of antihypertensives. Much less is known about RAS in the central nervous system. The production of RAS peptides and the expression of several RAS enzymes and receptors in dopaminergic neurons of the substantia nigra has raised expectations in the therapy of Parkinson's disease, a neurodegenerative condition characterized by lack of dopamine in the striatum, the motor control region of the mammalian brain. On the one hand, dopamine production requires reducing power. On the other hand, reducing power is required by mechanisms involved in REDOX homeostasis. This review focuses on the potential role of RAS in the regulation of neuronal/glial expression of glucose-6-phosphate dehydrogenase, which produces the NADPH required for dopamine synthesis and for reactive oxygen species (ROS) detoxification. It is known that transgenic expression of the gene coding for glucose-6-phosphate dehydrogenase prevents the death of dopaminergic nigral neurons. Signaling via angiotensin II G protein-coupled receptors, AT1 or AT2, leads to the activation of protein kinase A and/or protein kinase C that in turn can regulate glucose-6- phosphate dehydrogenase activity, by Ser/Thr phosphorylation/dephosphorylation events. Long-term effects of AT1 or AT2 receptor activation may also impact on the concentration of the enzyme via activation of transcription factors that participate in the regulation of gene expression in neurons (or glia). Future research is needed to determine how the system can be pharmacologically manipulated to increase the availability of NADPH to neurons degenerating in Parkinson's disease and to neuroprotective glia.

Fundamental Neurochemistry Review: Microglial immunometabolism in traumatic brain injury

Traumatic brain injury (TBI) is a devastating neurological disorder caused by a physical impact to the brain that promotes diffuse damage and chronic neurodegeneration. Key mechanisms believed to support secondary brain injury include mitochondrial dysfunction and chronic neuroinflammation. Microglia and brain-infiltrating macrophages are responsible for neuroinflammatory cytokine and reactive oxygen species (ROS) production after TBI. Their production is associated with loss of homeostatic microglial functions such as immunosurveillance, phagocytosis, and immune resolution. Beyond providing energy support, mitochondrial metabolic pathways reprogram the pro- and anti-inflammatory machinery in immune cells, providing a critical immunometabolic axis capable of regulating immunologic response to noxious stimuli. In the brain, the capacity to adapt to different environmental stimuli derives, in part, from microglia's ability to recognize and respond to changes in extracellular and intracellular metabolite levels. This capacity is met by an equally plastic metabolism, capable of altering immune function. Microglial pro-inflammatory activation is associated with decreased mitochondrial respiration, whereas anti-inflammatory microglial polarization is supported by increased oxidative metabolism. These metabolic adaptations contribute to neuroimmune responses, placing mitochondria as a central regulator of post-traumatic neuroinflammation. Although it is established that profound neurometabolic changes occur following TBI, key questions related to metabolic shifts in microglia remain unresolved. These include (a) the nature of microglial mitochondrial dysfunction after TBI, (b) the hierarchical positions of different metabolic pathways such as glycolysis, pentose phosphate pathway, glutaminolysis, and lipid oxidation during secondary injury and recovery, and (c) how immunometabolism alters microglial phenotypes, culminating in chronic non-resolving neuroinflammation. In this basic neurochemistry review article, we describe the contributions of immunometabolism to TBI, detail primary evidence of mitochondrial dysfunction and metabolic impairments in microglia and macrophages, discuss how major metabolic pathways contribute to post-traumatic neuroinflammation, and set out future directions toward advancing immunometabolic phenotyping in TBI.

G6PDi-1 is a Potent Inhibitor of G6PDH and of Pentose Phosphate pathway-dependent Metabolic Processes in Cultured Primary Astrocytes

Glucose-6-phosphate dehydrogenase (G6PDH) catalyses the rate limiting first step of the oxidative part of the pentose phosphate pathway (PPP), which has a crucial function in providing NADPH for antioxidative defence and reductive biosyntheses. To explore the potential of the new G6PDH inhibitor G6PDi-1 to affect astrocytic metabolism, we investigated the consequences of an application of G6PDi-1 to cultured primary rat astrocytes. G6PDi-1 efficiently inhibited G6PDH activity in lysates of astrocyte cultures. Half-maximal inhibition was observed for 100 nM G6PDi-1, while presence of almost 10 µM of the frequently used G6PDH inhibitor dehydroepiandrosterone was needed to inhibit G6PDH in cell lysates by 50%. Application of G6PDi-1 in concentrations of up to 100 µM to astrocytes in culture for up to 6 h did not affect cell viability nor cellular glucose consumption, lactate production, basal glutathione (GSH) export or the high basal cellular ratio of GSH to glutathione disulfide (GSSG). In contrast, G6PDi-1 drastically affected astrocytic pathways that depend on the PPP-mediated supply of NADPH, such as the NAD(P)H quinone oxidoreductase (NQO1)-mediated WST1 reduction and the glutathione reductase-mediated regeneration of GSH from GSSG. These metabolic pathways were lowered by G6PDi-1 in a concentration-dependent manner in viable astrocytes with half-maximal effects observed for concentrations between 3 and 6 µM. The data presented demonstrate that G6PDi-1 efficiently inhibits the activity of astrocytic G6PDH and impairs specifically those metabolic processes that depend on the PPP-mediated regeneration of NADPH in cultured astrocytes.

Assessing Metabolic Differences Associated with Exposure to Polybrominated Biphenyl and Polychlorinated Biphenyls in the Michigan PBB Registry

BACKGROUND

Polybrominated biphenyls (PBB) and polychlorinated biphenyls (PCB) are persistent organic pollutants with potential endocrine-disrupting effects linked to adverse health outcomes.

OBJECTIVES

In this study, we utilize high-resolution metabolomics (HRM) to identify internal exposure and biological responses underlying PCB and multigenerational PBB exposure for participants enrolled in the Michigan PBB Registry.

METHODS

HRM profiling was conducted on plasma samples collected from 2013 to 2014 from a subset of participants enrolled in the Michigan PBB Registry, including 369 directly exposed individuals (F0) who were alive when PBB mixtures were accidentally introduced into the food chain and 129 participants exposed to PBB in utero or through breastfeeding, if applicable (F1). Metabolome-wide association studies were performed for PBB-153 separately for each generation and Σ PCB (PCB-118, PCB-138, PCB-153, and PCB-180) in the two generations combined, as both had direct PCB exposure. Metabolite and metabolic pathway alterations were evaluated following a well-established untargeted HRM workflow.

RESULTS

Mean levels were 1.75  ng / mL [standard deviation (SD): 13.9] for PBB-153 and 1.04  ng / mL (SD: 0.788) for Σ PCB . Sixty-two and 26 metabolic features were significantly associated with PBB-153 in F0 and F1 [false discovery rate (FDR) p < 0.2 ], respectively. There were 2,861 features associated with Σ PCB (FDR p < 0.2 ). Metabolic pathway enrichment analysis using a bioinformatics tool revealed perturbations associated with Σ PCB in numerous oxidative stress and inflammation pathways (e.g., carnitine shuttle, glycosphingolipid, and vitamin B9 metabolism). Metabolic perturbations associated with PBB-153 in F0 were related to oxidative stress (e.g., pentose phosphate and vitamin C metabolism) and in F1 were related to energy production (e.g., pyrimidine, amino sugars, and lysine metabolism). Using authentic chemical standards, we confirmed the chemical identity of 29 metabolites associated with Σ PCB levels (level 1 evidence).

CONCLUSIONS

Our results demonstrate that serum PBB-153 is associated with alterations in inflammation and oxidative stress-related pathways, which differed when stratified by generation. We also found that Σ PCB was associated with the downregulation of important neurotransmitters, serotonin, and 4-aminobutanoate. These findings provide novel insights for future investigations of molecular mechanisms underlying PBB and PCB exposure on health. https://doi.org/10.1289/EHP12657.

Microglial Metabolic Reprogramming: Emerging Insights and Therapeutic Strategies in Neurodegenerative Diseases

Microglia, the resident immune cells of the central nervous system, play a critical role in maintaining brain homeostasis. However, in neurodegenerative conditions, microglial cells undergo metabolic reprogramming in response to pathological stimuli, including Aβ plaques, Tau tangles, and α-synuclein aggregates. This metabolic shift is characterized by a transition from oxidative phosphorylation (OXPHOS) to glycolysis, increased glucose uptake, enhanced production of lactate, lipids, and succinate, and upregulation of glycolytic enzymes. These metabolic adaptations result in altered microglial functions, such as amplified inflammatory responses and diminished phagocytic capacity, which exacerbate neurodegeneration. This review highlights recent advances in understanding the molecular mechanisms underlying microglial metabolic reprogramming in neurodegenerative diseases and discusses potential therapeutic strategies targeting microglial metabolism to mitigate neuroinflammation and promote brain health. Microglial Metabolic Reprogramming in Neurodegenerative Diseases This graphical abstract illustrates the metabolic shift in microglial cells in response to pathological stimuli and highlights potential therapeutic strategies targeting microglial metabolism for improved brain health.

Novel Approaches to the Establishment of Local Microenvironment from Resorbable Biomaterials in the Brain In Vitro Models

The development of brain in vitro models requires the application of novel biocompatible materials and biopolymers as scaffolds for controllable and effective cell growth and functioning. The "ideal" brain in vitro model should demonstrate the principal features of brain plasticity like synaptic transmission and remodeling, neurogenesis and angiogenesis, and changes in the metabolism associated with the establishment of new intercellular connections. Therefore, the extracellular scaffolds that are helpful in the establishment and maintenance of local microenvironments supporting brain plasticity mechanisms are of critical importance. In this review, we will focus on some carbohydrate metabolites-lactate, pyruvate, oxaloacetate, malate-that greatly contribute to the regulation of cell-to-cell communications and metabolic plasticity of brain cells and on some resorbable biopolymers that may reproduce the local microenvironment enriched in particular cell metabolites.

Metabolic reprogramming and polarization of microglia in Parkinson's disease: Role of inflammasome and iron

Parkinson's disease (PD) is a slowly progressive neurodegenerative disease characterized by α-synuclein aggregation and dopaminergic neuronal death. Recent evidence suggests that neuroinflammation is an early event in the pathogenesis of PD. Microglia are resident immune cells in the central nervous system that can be activated into either pro-inflammatory M1 or anti-inflammatory M2 phenotypes as found in peripheral macrophages. To exert their immune functions, microglia respond to various stimuli, resulting in the flexible regulation of their metabolic pathways. Inflammasomes activation in microglia induces metabolic shift from oxidative phosphorylation to glycolysis, and leads to the polarization of microglia to pro-inflammatory M1 phenotype, finally causing neuroinflammation and neurodegeneration. In addition, iron accumulation induces microglia take an inflammatory and glycolytic phenotype. M2 phenotype microglia is more sensitive to ferroptosis, inhibition of which can attenuate neuroinflammation. Therefore, this review highlights the interplay between microglial polarization and metabolic reprogramming of microglia. Moreover, it will interpret how inflammasomes and iron regulate microglial metabolism and phenotypic shifts, which provides a promising therapeutic target to modulate neuroinflammation and neurodegeneration in PD and other neurodegenerative diseases.

Role of microglial metabolic reprogramming in Parkinson's disease

Parkinson's disease (PD) is a common age-related neurodegenerative disorder characterized by damage to nigrostriatal dopaminergic neurons. Key pathogenic mechanisms underlying PD include alpha-synuclein misfolding and aggregation, impaired protein clearance, mitochondrial dysfunction, oxidative stress, and neuroinflammation. However, to date, no study has confirmed the specific pathogenesis of PD. Similarly, current PD treatment methods still have shortcomings. Although some emerging therapies have proved effective for PD, the specific mechanism still needs further clarification. Metabolic reprogramming, a term first proposed by Warburg, is applied to the metabolic energy characteristics of tumor cells. Microglia have similar metabolic characteristics. Pro-inflammatory M1 type and anti-inflammatory M2 type are the two types of activated microglia, which exhibit different metabolic patterns in glucose, lipid, amino acid, and iron metabolism. Additionally, mitochondrial dysfunction may be involved in microglial metabolic reprogramming by activating various signaling mechanisms. Functional changes in microglia resulting from metabolic reprogramming can cause changes in the brain microenvironment, thus playing an important role in neuroinflammation or tissue repair. The involvement of microglial metabolic reprogramming in PD pathogenesis has been confirmed. Neuroinflammation and dopaminergic neuronal death can effectively be reduced by inhibiting certain metabolic pathways in M1 microglia or reverting M1 cells to the M2 phenotype. This review summarizes the relationship between microglial metabolic reprogramming and PD and provides strategies for PD treatment.

Oral and fecal microbiota perturbance in cocaine users: Can rTMS-induced cocaine abstinence support eubiosis restoration?

The effects of cocaine on microbiota have been scarcely explored. Here, we investigated the gut (GM) and oral (OM) microbiota composition of cocaine use disorder (CUD) patients and the effects of repetitive transcranial magnetic stimulation (rTMS). 16S rRNA sequencing was used to characterize GM and OM, whereas PICRUST2 assessed functional changes in microbial communities, and gas-chromatography was used to evaluate fecal short and medium chain fatty acids. CUD patients reported a significant decrease in alpha diversity and modification of the abundances of several taxa in both GM and OM. Furthermore, many predicted metabolic pathways were differentially expressed in CUD patients' stool and saliva samples, as well as reduced levels of butyric acid that appear restored to normal amounts after rTMS treatment. In conclusion, CUD patients showed a profound dysbiotic fecal and oral microbiota composition and function and rTMS-induced cocaine abstinence determined the restoration of eubiotic microbiota.

Glucose Metabolism Impairment in Parkinson's Disease

Impairments in systematic and regional glucose metabolism exist in patients with Parkinson's disease (PD) at every stage of the disease course, and such impairments are associated with the incidence, progression, and special phenotypes of PD, which affect each physiological process of glucose metabolism including glucose uptake, glycolysis, tricarboxylic acid cycle, oxidative phosphorylation, and pentose phosphate shunt pathway. These impairments may be attributed to various mechanisms, such as insulin resistance, oxidative stress, abnormal glycated modification, blood-brain-barrier dysfunction, and hyperglycemia-induced damages. These mechanisms could subsequently cause excessive methylglyoxal and reactive oxygen species production, neuroinflammation, abnormal aggregation of protein, mitochondrial dysfunction, and decreased dopamine, and finally result in energy supply insufficiency, neurotransmitter dysregulation, aggregation and phosphorylation of α-synuclein, and dopaminergic neuron loss. This review discusses the glucose metabolism impairment in PD and its pathophysiological mechanisms, and briefly summarized the currently-available therapies targeting glucose metabolism impairment in PD, including glucagon-likepeptide-1 (GLP-1) receptor agonists and dual GLP-1/gastric inhibitory peptide receptor agonists, metformin, and thiazoledinediones.

Activation of neuronal NADPH oxidase NOX2 promotes inflammatory neurodegeneration

Strong evidence indicates critical roles of NADPH oxidase (a key superoxide-producing enzyme complex during inflammation) in activated microglia for mediating neuroinflammation and neurodegeneration. However, little is known about roles of neuronal NADPH oxidase in neurodegenerative diseases. This study aimed to investigate expression patterns, regulatory mechanisms and pathological roles of neuronal NADPH oxidase in inflammation-associated neurodegeneration. The results showed persistent upregulation of NOX2 (gp91phox; the catalytic subunit of NADPH oxidase) in both microglia and neurons in a chronic mouse model of Parkinson's disease (PD) with intraperitoneal LPS injection and LPS-treated midbrain neuron-glia cultures (a cellular model of PD). Notably, NOX2 was found for the first time to exhibit a progressive and persistent upregulation in neurons during chronic neuroinflammation. While primary neurons and N27 neuronal cells displayed basal expression of NOX1, NOX2 and NOX4, significant upregulation only occurred in NOX2 but not NOX1 or NOX4 under inflammatory conditions. Persistent NOX2 upregulation was associated with functional outcomes of oxidative stress including increased ROS production and lipid peroxidation. Neuronal NOX2 activation displayed membrane translocation of cytosolic p47phox subunit and was inhibited by apocynin and diphenyleneiodonium chloride (two widely-used NADPH oxidase inhibitors). Importantly, neuronal ROS production, mitochondrial dysfunction and degeneration induced by inflammatory mediators in microglia-derived conditional medium were blocked by pharmacological inhibition of neuronal NOX2. Furthermore, specific deletion of neuronal NOX2 prevented LPS-elicited dopaminergic neurodegeneration in neuron-microglia co-cultures separately grown in the transwell system. The attenuation of inflammation-elicited upregulation of NOX2 in neuron-enriched and neuron-glia cultures by ROS scavenger N-acetylcysteine indicated a positive feedback mechanism between excessive ROS production and NOX2 upregulation. Collectively, our findings uncovered crucial contribution of neuronal NOX2 upregulation and activation to chronic neuroinflammation and inflammation-related neurodegeneration. This study reinforced the importance of developing NADPH oxidase-targeting therapeutics for neurodegenerative diseases.

Molecular and metabolic heterogeneity of astrocytes and microglia

Astrocytes and microglia are central players in a myriad of processes in the healthy and diseased brain, ranging from metabolism to immunity. The crosstalk between these two cell types contributes to pathology in many if not all neuroinflammatory and neurodegenerative diseases. Recent advancements in integrative multimodal sequencing techniques have begun to highlight how heterogeneous both cell types are and the importance of metabolism to their regulation. We discuss here the transcriptomic, metabolic, and functional heterogeneity of astrocytes and microglia and highlight their interaction in health and disease.

Gastrodin and Gastrodigenin Improve Energy Metabolism Disorders and Mitochondrial Dysfunction to Antagonize Vascular Dementia

Vascular dementia (VD) is the second most common dementia syndrome worldwide, and effective treatments are lacking. Gastrodia elata Blume (GEB) has been used in traditional Chinese herbal medicine for centuries to treat cognitive impairment, ischemic stroke, epilepsy, and dizziness. Gastrodin (p-hydroxymethylphenyl-b-D-glucopyranoside, Gas) and Gastrodigenin (p-hydroxybenzyl alcohol, HBA) are the main bioactive components of GEB. This study explored the effects of Gas and HBA on cognitive dysfunction in VD and their possible molecular mechanisms. The VD model was established by bilateral common carotid artery ligation (2-vessel occlusion, 2-VO) combined with an intraperitoneal injection of sodium nitroprusside solution. One week after modeling, Gas (25 and 50 mg/kg, i.g.) and HBA (25 and 50 mg/kg, i.g.) were administered orally for four weeks, and the efficacy was evaluated. A Morris water maze test and passive avoidance test were used to observe their cognitive function, and H&E staining and Nissl staining were used to observe the neuronal morphological changes; the expressions of Aβ1-42 and p-tau396 were detected by immunohistochemistry, and the changes in energy metabolism in the brain tissue of VD rats were analyzed by targeted quantitative metabolomics. Finally, a Hippocampus XF analyzer measured mitochondrial respiration in H2O2-treated HT-22 cells. Our study showed that Gas and HBA attenuated learning memory dysfunction and neuronal damage and reduced the accumulation of Aβ1-42, P-Tau396, and P-Tau217 proteins in the brain tissue. Furthermore, Gas and HBA improved energy metabolism disorders in rats, involving metabolic pathways such as glycolysis, tricarboxylic acid cycle, and the pentose phosphate pathway, and reducing oxidative damage-induced cellular mitochondrial dysfunction. The above results indicated that Gas and HBA may exert neuroprotective effects on VD by regulating energy metabolism and mitochondrial function.

In Silico Localization of Perilymph Proteins Enriched in Meńier̀e Disease Using Mammalian Cochlear Single-cell Transcriptomics

Hypothesis

Proteins enriched in the perilymph proteome of Meńier̀e disease (MD) patients may identify affected cell types. Utilizing single-cell transcriptome datasets from the mammalian cochlea, we hypothesize that these enriched perilymph proteins can be localized to specific cochlear cell types.

Background

The limited understanding of human inner ear pathologies and their associated biomolecular variations hinder efforts to develop disease-specific diagnostics and therapeutics. Perilymph sampling and analysis is now enabling further characterization of the cochlear microenvironment. Recently, enriched inner ear protein expression has been demonstrated in patients with MD compared to patients with other inner ear diseases. Localizing expression of these proteins to cochlear cell types can further our knowledge of potential disease pathways and subsequent development of targeted therapeutics.

Methods

We compiled previously published data regarding differential perilymph proteome profiles amongst patients with MD, otosclerosis, enlarged vestibular aqueduct, sudden hearing loss, and hearing loss of undefined etiology (controls). Enriched proteins in MD were cross-referenced against published single-cell/single-nucleus RNA-sequencing datasets to localize gene expression to specific cochlear cell types.

Results

In silico analysis of single-cell transcriptomic datasets demonstrates enrichment of a unique group of perilymph proteins associated with MD in a variety of intracochlear cells, and some exogeneous hematologic and immune effector cells. This suggests that these cell types may play an important role in the pathology associated with late MD, suggesting potential future areas of investigation for MD pathophysiology and treatment.

Conclusions

Perilymph proteins enriched in MD are expressed by specific cochlear cell types based on in silico localization, potentially facilitating development of disease-specific diagnostic markers and therapeutics.

The Protective Role of Glutathione on Zinc-Induced Neuron Death after Brain Injuries

Glutathione (GSH) is necessary for maintaining physiological antioxidant function, which is responsible for maintaining free radicals derived from reactive oxygen species at low levels and is associated with improved cognitive performance after brain injury. GSH is produced by the linkage of tripeptides that consist of glutamic acid, cysteine, and glycine. The adequate supplementation of GSH has neuroprotective effects in several brain injuries such as cerebral ischemia, hypoglycemia, and traumatic brain injury. Brain injuries produce an excess of reactive oxygen species through complex biochemical cascades, which exacerbates primary neuronal damage. GSH concentrations are known to be closely correlated with the activities of certain genes such as excitatory amino acid carrier 1 (EAAC1), glutamate transporter-associated protein 3-18 (Gtrap3-18), and zinc transporter 3 (ZnT3). Following brain-injury-induced oxidative stress, EAAC1 function is negatively impacted, which then reduces cysteine absorption and impairs neuronal GSH synthesis. In these circumstances, vesicular zinc is also released into the synaptic cleft and then translocated into postsynaptic neurons. The excessive influx of zinc inhibits glutathione reductase, which inhibits GSH's antioxidant functions in neurons, resulting in neuronal damage and ultimately in the impairment of cognitive function. Therefore, in this review, we explore the overall relationship between zinc and GSH in terms of oxidative stress and neuronal cell death. Furthermore, we seek to understand how the modulation of zinc can rescue brain-insult-induced neuronal death after ischemia, hypoglycemia, and traumatic brain injury.