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    15 July 2023, Volume 18 Issue 7 Previous Issue    Next Issue
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    Bystanders or not? Microglia and lymphocytes in aging and stroke
    Justin N. Nguyen, Anjali Chauhan
    2023, 18 (7):  1397-1403.  doi: 10.4103/1673-5374.360345
    Abstract ( 170 )   PDF (830KB) ( 212 )   Save
    As the average age of the world population increases, more people will face debilitating aging-associated conditions, including dementia and stroke. Not only does the incidence of these conditions increase with age, but the recovery afterward is often worse in older patients. Researchers and health professionals must unveil and understand the factors behind age-associated diseases to develop a therapy for older patients. Aging causes profound changes in the immune system including the activation of microglia in the brain. Activated microglia promote T lymphocyte transmigration leading to an increase in neuroinflammation, white matter damage, and cognitive impairment in both older humans and rodents. The presence of T and B lymphocytes is observed in the aged brain and correlates with worse stroke outcomes. Preclinical strategies in stroke target either microglia or the lymphocytes or the communications between them to promote functional recovery in aged subjects. In this review, we examine the role of the microglia and T and B lymphocytes in aging and how they contribute to cognitive impairment. Additionally, we provide an important update on the contribution of these cells and their interactions in preclinical aged stroke.
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    Alzheimer’s disease risk after COVID-19: a view from the perspective of the infectious hypothesis of neurodegeneration
    Eugenia Olivera, Albany Sáez, Lila Carniglia, Carla Caruso, Mercedes Lasaga, Daniela Durand
    2023, 18 (7):  1404-1410.  doi: 10.4103/1673-5374.360273
    Abstract ( 272 )   PDF (974KB) ( 87 )   Save
    In light of the rising evidence of the association between viral and bacterial infections and neurodegeneration, we aimed at revisiting the infectious hypothesis of Alzheimer’s disease and analyzing the possible implications of COVID-19 neurological sequelae in long-term neurodegeneration. We wondered how SARS-CoV-2 could be related to the amyloid-β cascade and how it could lead to the pathological hallmarks of the disease. We also predict a paradigm change in clinical medicine, which now has a great opportunity to conduct prospective surveillance of cognitive sequelae and progression to dementia in people who suffered severe infections together with other risk factors for Alzheimer’s disease.
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    Serine and arginine rich splicing factor 1: a potential target for neuroprotection and other diseases
    Ana M. Sandoval-Castellanos, Anushka Bhargava, Min Zhao, Jun Xu, Ke Ning
    2023, 18 (7):  1411-1416.  doi: 10.4103/1673-5374.360243
    Abstract ( 126 )   PDF (445KB) ( 36 )   Save
    Alternative splicing is the process of producing variably spliced mRNAs by choosing distinct combinations of splice sites within a messenger RNA precursor. This splicing enables mRNA from a single gene to synthesize different proteins, which have different cellular properties and functions and yet arise from the same single gene. A family of splicing factors, Serine-arginine rich proteins, are needed to initiate the assembly and activation of the spliceosome. Serine and arginine rich splicing factor 1, part of the arginine/serine-rich splicing factor protein family, can either activate or inhibit the splicing of mRNAs, depending on the phosphorylation status of the protein and its interaction partners. Considering that serine and arginine rich splicing factor 1 is either an activator or an inhibitor, this protein has been studied widely to identify its various roles in different diseases. Research has found that serine and arginine rich splicing factor 1 is a key target for neuroprotection, showing its promising potential use in therapeutics for neurodegenerative disorders. Furthermore, serine and arginine rich splicing factor 1 might be used to regulate cancer development and autoimmune diseases. In this review, we highlight how serine and arginine rich splicing factor 1 has been studied concerning neuroprotection. In addition, we draw attention to how serine and arginine rich splicing factor 1 is being studied in cancer and immunological disorders, as well as how serine and arginine rich splicing factor 1 acts outside the central or peripheral nervous system.
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    Can glial cells save neurons in epilepsy?
    Weida Shen, Jelena Bogdanović Pristov, Paola Nobili, Ljiljana Nikolić
    2023, 18 (7):  1417-1422.  doi: 10.4103/1673-5374.360281
    Abstract ( 127 )   PDF (505KB) ( 54 )   Save
    Epilepsy is a neurological disorder caused by the pathological hyper-synchronization of neuronal discharges. The fundamental research of epilepsy mechanisms and the targets of drug design options for its treatment have focused on neurons. However, approximately 30% of patients suffering from epilepsy show resistance to standard anti-epileptic chemotherapeutic agents while the symptoms of the remaining 70% of patients can be alleviated but not completely removed by the current medications. Thus, new strategies for the treatment of epilepsy are in urgent demand. Over the past decades, with the increase in knowledge on the role of glia in the genesis and development of epilepsy, glial cells are receiving renewed attention. In a normal brain, glial cells maintain neuronal health and in partnership with neurons regulate virtually every aspect of brain function. In epilepsy, however, the supportive roles of glial cells are compromised, and their interaction with neurons is altered, which disrupts brain function. In this review, we will focus on the role of glia-related processes in epileptogenesis and their contribution to abnormal neuronal activity, with the major focus on the dysfunction of astroglial potassium channels, water channels, gap junctions, glutamate transporters, purinergic signaling, synaptogenesis, on the roles of microglial inflammatory cytokines, microglia-astrocyte interactions in epilepsy, and on the oligodendroglial potassium channels and myelin abnormalities in the epileptic brain. These recent findings suggest that glia should be considered as the promising next-generation targets for designing anti-epileptic drugs that may improve epilepsy and drug-resistant epilepsy.
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    Lights for epilepsy: can photobiomodulation reduce seizures and offer neuroprotection?
    Napoleon Torres-Martinez, Stephan Chabardes, John Mitrofanis
    2023, 18 (7):  1423-1426.  doi: 10.4103/1673-5374.360288
    Abstract ( 150 )   PDF (40461KB) ( 46 )   Save
    Epilepsy is synonymous with individuals suffering repeated “fits” or seizures. The seizures are triggered by bursts of abnormal neuronal activity, across either the cerebral cortex and/or the hippocampus. In addition, the seizure sites are characterized by considerable neuronal death. Although the factors that generate this abnormal activity and death are not entirely clear, recent evidence indicates that mitochondrial dysfunction plays a central role. Current treatment options include drug therapy, which aims to suppress the abnormal neuronal activity, or surgical intervention, which involves the removal of the brain region generating the seizure activity. However, ~30% of patients are unresponsive to the drugs, while the surgery option is invasive and has a morbidity risk. Hence, there is a need for the development of an effective non-pharmacological and non-invasive treatment for this disorder, one that has few side effects. In this review, we consider the effectiveness of a potential new treatment for epilepsy, known as photobiomodulation, the use of red to near-infrared light on body tissues. Recent studies in animal models have shown that photobiomodulation reduces seizure-like activity and improves neuronal survival. Further, it has an excellent safety record, with little or no evidence of side effects, and it is non-invasive. Taken all together, this treatment appears to be an ideal treatment option for patients suffering from epilepsy, which is certainly worthy of further consideration.
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    The landscape of cognitive impairment in superoxide dismutase 1-amyotrophic lateral sclerosis
    Ilaria Martinelli, Elisabetta Zucchi, Cecilia Simonini, Giulia Gianferrari, Giovanna Zamboni, Marcello Pinti, Jessica Mandrioli
    2023, 18 (7):  1427-1433.  doi: 10.4103/1673-5374.361535
    Abstract ( 130 )   PDF (730KB) ( 34 )   Save
    Although mutations in the superoxide dismutase 1 gene account for only a minority of total amyotrophic lateral sclerosis cases, the discovery of this gene has been crucial for amyotrophic lateral sclerosis research. Since the identification of superoxide dismutase 1 in 1993, the field of amyotrophic lateral sclerosis genetics has considerably widened, improving our understanding of the diverse pathogenic basis of amyotrophic lateral sclerosis. In this review, we focus on cognitive impairment in superoxide dismutase 1-amyotrophic lateral sclerosis patients. Literature has mostly reported that cognition remains intact in superoxide dismutase 1-amyotrophic lateral sclerosis patients, but recent reports highlight frontal lobe function frailty in patients carrying different superoxide dismutase 1-amyotrophic lateral sclerosis mutations. We thoroughly reviewed all the various mutations reported in the literature to contribute to a comprehensive database of superoxide dismutase 1-amyotrophic lateral sclerosis genotype-phenotype correlation. Such a resource could ultimately improve our mechanistic understanding of amyotrophic lateral sclerosis, enabling a more robust assessment of how the amyotrophic lateral sclerosis phenotype responds to different variants across genes, which is important for the therapeutic strategy targeting genetic mutations. Cognition in superoxide dismutase 1-amyotrophic lateral sclerosis deserves further longitudinal research since this peculiar frailty in patients with similar mutations can be conditioned by external factors, including environment and other unidentified agents including modifier genes. 
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    CMT1A current gene therapy approaches and promising biomarkers
    Marina Stavrou, Kleopas A. Kleopa
    2023, 18 (7):  1434-1440.  doi: 10.4103/1673-5374.361538
    Abstract ( 176 )   PDF (1381KB) ( 58 )   Save
    Charcot-Marie-Tooth neuropathies (CMT) constitute a group of common but highly heterogeneous, non-syndromic genetic disorders affecting predominantly the peripheral nervous system. CMT type 1A (CMT1A) is the most frequent type and accounts for almost ~50% of all diagnosed CMT cases. CMT1A results from the duplication of the peripheral myelin protein 22 (PMP22) gene. Overexpression of PMP22 protein overloads the protein folding apparatus in Schwann cells and activates the unfolded protein response. This leads to Schwann cell apoptosis, dys- and de- myelination and secondary axonal degeneration, ultimately causing neurological disabilities. During the last decades, several different gene therapies have been developed to treat CMT1A. Almost all of them remain at the pre-clinical stage using CMT1A animal models overexpressing PMP22. The therapeutic goal is to achieve gene silencing, directly or indirectly, thereby reversing the CMT1A genetic mechanism allowing the recovery of myelination and prevention of axonal loss. As promising treatments are rapidly emerging, treatment-responsive and clinically relevant biomarkers are becoming necessary. These biomarkers and sensitive clinical evaluation tools will facilitate the design and successful completion of future clinical trials for CMT1A. 
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    Epigenetic modifications and metabolic memory in diabetic retinopathy: beyond the surface
    Dan-Dan Liu, Chao-Yang Zhang, Jing-Ting Zhang, Li-Min Gu, Guo-Tong Xu, Jing-Fa Zhang
    2023, 18 (7):  1441-1449.  doi: 10.4103/1673-5374.361536
    Abstract ( 212 )   PDF (3319KB) ( 138 )   Save
    Epigenetics focuses on DNA methylation, histone modification, chromatin remodeling, noncoding RNAs, and other gene regulation mechanisms beyond the DNA sequence. In the past decade, epigenetic modifications have drawn more attention as they participate in the development and progression of diabetic retinopathy despite tight control of glucose levels. The underlying mechanisms of epigenetic modifications in diabetic retinopathy still urgently need to be elucidated. The diabetic condition facilitates epigenetic changes and influences target gene expression. In this review, we summarize the involvement of epigenetic modifications and metabolic memory in the development and progression of diabetic retinopathy and propose novel insights into the treatment of diabetic retinopathy. 
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    Molecular mechanisms underlying the neuroprotection of environmental enrichment in Parkinson’s disease
    Tamara Andrea Alarcón, Sarah Martins Presti-Silva, Ana Paula Toniato Simões, Fabiola Mara Ribeiro, Rita Gomes Wanderley Pires
    2023, 18 (7):  1450-1456.  doi: 10.4103/1673-5374.360264
    Abstract ( 140 )   PDF (10586KB) ( 23 )   Save
    Parkinson’s disease is the most common movement disorder, affecting about 1% of the population over the age of 60 years. Parkinson’s disease is characterized clinically by resting tremor, bradykinesia, rigidity and postural instability, as a result of the progressive loss of nigrostriatal dopaminergic neurons. In addition to this neuronal cell loss, Parkinson’s disease is characterized by the accumulation of intracellular protein aggregates, Lewy bodies and Lewy neurites, composed primarily of the protein α-synuclein. Although it was first described almost 200 years ago, there are no disease-modifying drugs to treat patients with Parkinson’s disease. In addition to conventional therapies, non-pharmacological treatment strategies are under investigation in patients and animal models of neurodegenerative disorders. Among such strategies, environmental enrichment, comprising physical exercise, cognitive stimulus, and social interactions, has been assessed in preclinical models of Parkinson’s disease. Environmental enrichment can cause structural and functional changes in the brain and promote neurogenesis and dendritic growth by modifying gene expression, enhancing the expression of neurotrophic factors and modulating neurotransmission. In this review article, we focus on the current knowledge about the molecular mechanisms underlying environmental enrichment neuroprotection in Parkinson’s disease, highlighting its influence on the dopaminergic, cholinergic, glutamatergic and GABAergic systems, as well as the involvement of neurotrophic factors. We describe experimental pre-clinical data showing how environmental enrichment can act as a modulator in a neurochemical and behavioral context in different animal models of Parkinson’s disease, highlighting the potential of environmental enrichment as an additional strategy in the management and prevention of this complex disease. 
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    Regulation of enolase activation to promote neural protection and regeneration in spinal cord injury
    Hannah M. McCoy, Rachel Polcyn, Naren L. Banik, Azizul Haque
    2023, 18 (7):  1457-1462.  doi: 10.4103/1673-5374.361539
    Abstract ( 144 )   PDF (1035KB) ( 40 )   Save
    Spinal cord injury (SCI) is a debilitating condition characterized by damage to the spinal cord resulting in loss of function, mobility, and sensation with no U.S. Food and Drug Administration-approved cure. Enolase, a multifunctional glycolytic enzyme upregulated after SCI, promotes pro- and anti-inflammatory events and regulates functional recovery in SCI. Enolase is normally expressed in the cytosol, but the expression is upregulated at the cell surface following cellular injury, promoting glial cell activation and signal transduction pathway activation. SCI-induced microglia activation triggers pro-inflammatory mediators at the injury site, activating other immune cells and metabolic events, i.e., Rho-associated kinase, contributing to the neuroinflammation found in SCI. Enolase surface expression also activates cathepsin X, resulting in cleavage of the C-terminal end of neuron-specific enolase (NSE) and non-neuronal enolase (NNE). Fully functional enolase is necessary as NSE/NNE C-terminal proteins activate many neurotrophic processes, i.e., the plasminogen activation system, phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B, and mitogen-activated protein kinase/extracellular signal-regulated kinase. Studies here suggest an enolase inhibitor, ENOblock, attenuates the activation of Rho-associated kinase, which may decrease glial cell activation and promote functional recovery following SCI. Also, ENOblock inhibits cathepsin X, which may help prevent the cleavage of the neurotrophic C-terminal protein allowing full plasminogen activation and phosphatidylinositol-4,5-bisphosphate 3-kinase/mitogen-activated protein kinase activity. The combined NSE/cathepsin X inhibition may serve as a potential therapeutic strategy for preventing neuroinflammation/degeneration and promoting neural cell regeneration and recovery following SCI. The role of cell membrane-expressed enolase and associated metabolic events should be investigated to determine if the same strategies can be applied to other neurodegenerative diseases. Hence, this review discusses the importance of enolase activation and inhibition as a potential therapeutic target following SCI to promote neuronal survival and regeneration. 
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    Converging links between adult-onset neurodegenerative Alzheimer’s disease and early life neurodegenerative neuronal ceroid lipofuscinosis?
    Marcel Klein, Guido Hermey
    2023, 18 (7):  1463-1471.  doi: 10.4103/1673-5374.361544
    Abstract ( 125 )   PDF (2833KB) ( 61 )   Save
    Evidence from genetics and from analyzing cellular and animal models have converged to suggest links between neurodegenerative disorders of early and late life. Here, we summarize emerging links between the most common late life neurodegenerative disease, Alzheimer’s disease, and the most common early life neurodegenerative diseases, neuronal ceroid lipofuscinoses. Genetic studies reported an overlap of clinically diagnosed Alzheimer’s disease and mutations in genes known to cause neuronal ceroid lipofuscinoses. Accumulating data strongly suggest dysfunction of intracellular trafficking mechanisms and the autophagy-endolysosome system in both types of neurodegenerative disorders. This suggests shared cytopathological processes underlying these different types of neurodegenerative diseases. A better understanding of the common mechanisms underlying the different diseases is important as this might lead to the identification of novel targets for therapeutic concepts, the transfer of therapeutic strategies from one disease to the other and therapeutic approaches tailored to patients with specific mutations. Here, we review dysfunctions of the endolysosomal autophagy pathway in Alzheimer’s disease and neuronal ceroid lipofuscinoses and summarize emerging etiologic and genetic overlaps.
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    Mitochondria in Huntington’s disease: implications in pathogenesis and mitochondrial-targeted therapeutic strategies
    Anamaria Jurcau, Carolina Maria Jurcau
    2023, 18 (7):  1472-1477.  doi: 10.4103/1673-5374.360289
    Abstract ( 205 )   PDF (1427KB) ( 78 )   Save
    Huntington’s disease is a genetic disease caused by expanded CAG repeats on exon 1 of the huntingtin gene located on chromosome 4. Compelling evidence implicates impaired mitochondrial energetics, altered mitochondrial biogenesis and quality control, disturbed mitochondrial trafficking, oxidative stress and mitochondrial calcium dyshomeostasis in the pathogenesis of the disorder. Unfortunately, conventional mitochondrial-targeted molecules, such as cysteamine, creatine, coenzyme Q10, or triheptanoin, yielded negative or inconclusive results. However, future therapeutic strategies, aiming to restore mitochondrial biogenesis, improving the fission/fusion balance, and improving mitochondrial trafficking, could prove useful tools in improving the phenotype of Huntington’s disease and, used in combination with genome-editing methods, could lead to a cure for the disease.
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    Stem cell therapy in retinal diseases
    Audrey Voisin, Amaury Pénaguin, Afsaneh Gaillard, Nicolas Leveziel
    2023, 18 (7):  1478-1485.  doi: 10.4103/1673-5374.361537
    Abstract ( 177 )   PDF (1312KB) ( 98 )   Save
    Alteration of the outer retina leads to various diseases such as age-related macular degeneration or retinitis pigmentosa characterized by decreased visual acuity and ultimately blindness. Despite intensive research in the field of retinal disorders, there is currently no curative treatment. Several therapeutic approaches such as cell-based replacement and gene therapies are currently in development. In the context of cell-based therapies, different cell sources such as embryonic stem cells, induced pluripotent stem cells, or multipotent stem cells can be used for transplantation. In the vast majority of human clinical trials, retinal pigment epithelial cells and photoreceptors are the cell types considered for replacement cell therapies. In this review, we summarize the progress made in stem cell therapies ranging from the pre-clinical studies to clinical trials for retinal disease.
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    Overcoming mitochondrial dysfunction in neurodegenerative diseases
    João Pessoa, Ana I. Duarte
    2023, 18 (7):  1486-1488.  doi: 10.4103/1673-5374.360279
    Abstract ( 115 )   PDF (2428KB) ( 66 )   Save
    Due to their intense electrical activity, neurons have high energy demands. This requirement makes them particularly sensitive to mitochondrial dysfunction. Like all eukaryotic cells, neurons have intrinsic mechanisms to mitigate the impact of mitochondrial dysfunction and its consequent production of toxic substances. Among such (neuro)protective mechanisms, mitochondrial autophagy (mitophagy) is responsible for the removal of dysfunctional mitochondria. Pathological inhibition of mitophagy, together with insufficient mitochondrial activity, results in a shortage of adenosine triphosphate (ATP) and the accumulation of reactive oxygen species (ROS) (Simmons et al., 2020). These alterations may trigger extensive apoptotic neuronal death (Figure 1A) which, together with the post-mitotic nature of neurons, impedes the replacement of the apoptotic cells. This irreversible loss of neurons may underlie the progressive decline in the function of the central nervous system, culminating in the arousal of neurodegenerative diseases (Simmons et al., 2020). The actual role of mitochondrial dysfunction has been increasingly demonstrated in Alzheimer’s disease. For example, post-mortem analysis of patient brains has revealed the reduced expression and activity of mitochondrial respiratory chain complexes (Troutwine et al., 2022).
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    Functional hyperconnectivity related to brain disease: maladaptive process or element of resilience?
    Markus Aswendt, Mathias Hoehn
    2023, 18 (7):  1489-1490.  doi: 10.4103/1673-5374.361541
    Abstract ( 117 )   PDF (535KB) ( 49 )   Save
    Neuroimaging techniques such as magnetic resonance imaging (MRI) and positron emission tomography provide unique in vivo data to analyze structural and functional connectivity of the whole brain. Recent advances in small animal neuroimaging have opened new opportunities for the study of structure-function interactions in healthy and diseased brain networks, which are essential to develop therapies targeting network reorganization associated with functional improvement. Based on clinical studies, a common network response to acute neurological insult (e.g., stroke) and neurodegeneration (e.g., Alzheimer’s disease) is hyperconnectivity, i.e., an increase of functional connectivity strength above (healthy) control levels, a process which is, however, not well understood. For example, in resting-state functional MRI (rs-fMRI), which measures the hemodynamic response to neuronal activity, hyperconnectivity would refer to a drastic increase in the correlation between two regional time series. In absence of an absolute threshold defining hyperconnectivity, it relates to a control group or baseline measurement before intervention. It was hypothesized that hyperconnectivity follows a nonlinear distribution  representing an interaction between actual demands, injury severity, and resource availability  (Hillary and Grafman, 2017). Hyperconnectivity is significantly larger than transient variability in functional networks. The increase in connectivity follows a nonlinear distribution that reaches a maximum and transitions to a state of hypo-connectivity when a critical loss of structural resources is reached (Figure 1). As an extension of this hypothesis, we consider hyperconnectivity as part of an understudied and not well understood compensatory mechanism, which is embedded in the framework of the brain’s resilience capacity to respond to (network) disturbances. 
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    Aquaporin 5 in Alzheimer’s disease: a link between oral and brain pathology?
    Cristina Municio, Eva Carro
    2023, 18 (7):  1491-1492.  doi: 10.4103/1673-5374.361545
    Abstract ( 110 )   PDF (382KB) ( 36 )   Save
    The involvement of aquaporins (AQPs) in the development of diseases has been widely described (Azad et al., 2021). AQP5 has been described in astrocytes changing after traumatic brain injuries (Chai et al., 2013), but the precise role of AQP5 in Alzheimer’s disease (AD) pathology is yet to be understood. We have recently reported that AQP5 expression changes during the development of AD (Antequera et al., 2022). The AQP5 expression in salivary glands is decreased in 6-month-old APP/PS1 mice and AD patients. This decrease in AQP5 expression could be involved in the mechanism of salivary gland dysfunction described in a previous study (Antequera et al., 2021). Now, we propose a new indirect role of AQP5 in the connection between infection-induced oral dysbiosis and AD (Sureda et al., 2020). Here, we suggest that the proinflammatory response induced by oral pathogen infection results in the downregulation of AQP5 contributing to the salivary gland secretory dysfunction. All these alterations destabilize the peripheral immune-inflammatory balance and exacerbate neuroinflammation and neurodegeneration leading to AD pathology.
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    Generating oligodendroglia from adult mesenchymal cells for transplantation: cell reprogramming or direct lineage conversion?
    Jorge Pascual-Guerra, José A. Rodríguez-Navarro, Carlos L. Paíno
    2023, 18 (7):  1493-1494.  doi: 10.4103/1673-5374.360278
    Abstract ( 101 )   PDF (551KB) ( 54 )   Save
    Cell replacement therapy has long been proposed as a treatment for the damaged nervous system. One of the most challenging aspects of such a strategy, however, is finding sources of donor cells for transplantation. Autologous neural cells are rarely an option as every cell in the nervous system has a defined function that would be lost if that cell was to be removed. One possibility would be sourcing precursor or differentiated cells from fetal tissues; however, aside from ethical issues, heterologous cells are at risk of immunological rejection in the long term. Methodological improvements over the past 15 years have led to the possibility that autologous non-neural cells could be used for cell transplantation through their conversion into neural derivatives.
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    Pemafibrate, a potent selective peroxisome proliferator-activated receptor α modulator, a promising novel treatment for ischemic retinopathy?
    Deokho Lee, Yohei Tomita, Kazuno Negishi, Toshihide Kurihara
    2023, 18 (7):  1495-1496.  doi: 10.4103/1673-5374.360319
    Abstract ( 463 )   PDF (478KB) ( 87 )   Save
    Ischemic retinopathy is a retinal disease caused by ischemic attacks. Ischemia is a common pathologic mechanism in various retinal disorders and diseases such as age-related macular degeneration, diabetic retinopathy, glaucoma, or vascular occlusion (Osborne et al., 2004). Although various murine models have been developed to understand a series of metabolic mechanisms induced by retinal ischemia and further used to test promising therapeutics, effective treatment in ischemic retinopathy has not been clearly suggested. This is associated with the notion that the contributing pathologic metabolic pathways might be enormously complex.
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    From dolphins to dogs: new opportunities to understand the role of P2X4 receptors in spinal cord injury and neuropathic pain
    Reece A. Sophocleous, Ronald Sluyter
    2023, 18 (7):  1497-1498.  doi: 10.4103/1673-5374.360294
    Abstract ( 127 )   PDF (2602KB) ( 75 )   Save
    The P2X4 receptor belongs to the P2X receptor family of trimeric ligand-gated ion channels and was the first member of this family for which a crystal structure was obtained (Kawate et al., 2009). This structure confirmed the trimeric stoichiometry of P2X receptors and subsequent studies from the same group revealed the orthosteric binding site of the natural ligand adenosine 5′-triphosphate (ATP) in a cleft between each adjacent subunit (Hattori and Gouaux, 2012). Now synonymous with structural descriptions of P2X receptors, these original studies described the structure of each P2X4 receptor subunit as that resembling a dolphin, with the two transmembrane domains representing the fluke and the extracellular loop representing the upper body, including the head, dorsal fin, and left and right flippers. Along with subsequent structures of other P2X receptor members, obtained by either X-ray crystallography or cryo-electron microscopy, these studies have helped to further elucidate the agonist binding sites and conformational states during activation, as well as orthosteric and allosteric binding sites of P2X receptors (Mansoor, 2022). Transfer of this knowledge to the design of novel P2X4 receptor antagonists remains scant, with most antagonists described to date arising from the screening of chemical libraries and none advancing to clinical trials beyond NC-2600 (Inoue, 2021). Nevertheless, given the roles of the P2X4 receptor within the nervous system, this receptor remains an attractive therapeutic target in the treatment of a range of neurological disorders including pain (Sophocleous et al., 2022). In this regard, the screening of chemical libraries identified the anti-depressants, duloxetine and paroxetine as P2X4 receptor antagonists. This suggests that the historical use of such drugs to alleviate pain in people may have been, at least in part, due to P2X4 receptor inhibition and may warrant future trials for their potential use in humans to safely inhibit P2X4 receptor activity (Kohno and Tsuda, 2021).
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    Mutations in Hevin/Sparcl1 and risk of autism spectrum disorder
    Takumi Taketomi, Fuminori Tsuruta
    2023, 18 (7):  1499-1500.  doi: 10.4103/1673-5374.361543
    Abstract ( 148 )   PDF (634KB) ( 42 )   Save
    Hevin/Sparcl1 (hereafter referred to as Hevin) is an extracellular matrix protein encoded by the SPARCL1 gene. Recently, it has been revealed that Hevin has various functions, such as synapse formation, neuronal migration, inflammation, and angiogenesis (Gongidi et al., 2004; Naschberger et al., 2016; Singh et al., 2016; Liu et al., 2021). In addition, genome-wide association studies uncovered de novo and familial mutations of the SPARCL1 gene associated with a risk for autism spectrum disorder (ASD) (De Rubeis et al., 2014). However, the relationship between ASD-associated Hevin mutant and cellular phenotype has not been clarified. Recently, we have reported that ASD-associated mutation in Hevin reduces secretion efficiency and induces endoplasmic reticulum (ER) stress caused by structural instability (Taketomi et al., 2022). In this perspective, we discuss the relationship between the molecular functions of Hevin and ASD risk (Figure 1A). Also, we introduce our recent findings that link ASD-associated Hevin mutant to the cellular phenotype of ASD.
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    ew unexpected role for Wolfram Syndrome protein WFS1: a novel therapeutic target for Alzheimer’s disease?
    Shuo Chen, Diana Acosta, Hongjun Fu
    2023, 18 (7):  1501-1502.  doi: 10.4103/1673-5374.361540
    Abstract ( 121 )   PDF (724KB) ( 39 )   Save
    Selective vulnerability of excitatory neurons in Alzheimer’s disease (AD): AD is the most common form of dementia; however, the pathogenesis of AD is largely unknown. One of the characteristic features of AD is the formation of intracellular neurofibrillary tangles (NFTs). NFTs are abnormal accumulates of misfolded tau protein, which may eventually cause neuronal death and neurodegeneration (Jack et al., 2018). In the early stages of AD progression, not all neurons are equally vulnerable to tau aggregates. Previous studies have shown that large pyramidal neurons in the entorhinal cortex (EC) are specifically vulnerable to pathological tau accumulation (Fu et al., 2017). This selective vulnerability of excitatory neurons to tau pathology is one of the fundamental questions needed to be answered in AD research. 
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    Nociceptors are needed to guide tooth development, function, repair, and regeneration
    Sarah B. Peters, Joshua J. Emrick
    2023, 18 (7):  1503-1504.  doi: 10.4103/1673-5374.360280
    Abstract ( 106 )   PDF (22039KB) ( 22 )   Save
    Toothaches have received widespread attention and commentary dating back to ancient times, appearing in Egyptian texts from over 3000 years ago and the writings of Hippocrates, Aristotle, and Galen. Scientific studies of the innervation of dental pulp and dentin date back to at least the 1800’s, yet our understanding of the basis for tooth pain is still limited. Standard treatments for toothache continue to be drastic and irreversible, including removal of the dental pulp or extraction of the tooth. While the trigeminal sensory innervation of the tooth pulp is commonly the origin of toothache pain, it is also indispensable for normal function and physiology, and should be retained as an integral part of the repaired tooth. Repair or regeneration of the dental pulp and its innervation could represent the next step in restorative dentistry, but a better understanding of the roles of the tooth’s sensory nerve supply and the mechanisms underlying its development and repair is needed.
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    Molecular and cellular changes in the post-traumatic spinal cord remodeling after autoinfusion of a genetically-enriched leucoconcentrate in a mini-pig model
    Maria Aleksandrovna Davleeva, Ravil Rasimovich Garifulin, Farid Vagizovich Bashirov, Andrei Aleksandrovich Izmailov, Leniz Faritovich Nurullin, Ilnur Ildusovich Salafutdinov, Dilara Zilbarovna Gatina, Dmitrij Nikolaevich Shcherbinin, Andrei Aleksandrovich Lysenko, Irina Leonidovna Tutykhina, Maksim Mikhailovich Shmarov, Rustem Robertovich Islamov
    2023, 18 (7):  1505-1511.  doi: 10.4103/1673-5374.360241
    Abstract ( 140 )   PDF (7120KB) ( 37 )   Save
    Post-traumatic spinal cord remodeling includes both degenerating and regenerating processes, which affect the potency of the functional recovery after spinal cord injury (SCI). Gene therapy for spinal cord injury is proposed as a promising therapeutic strategy to induce positive changes in remodeling of the affected neural tissue. In our previous studies for delivering the therapeutic genes at the site of spinal cord injury, we developed a new approach using an autologous leucoconcentrate transduced ex vivo with chimeric adenoviruses (Ad5/35) carrying recombinant cDNA. In the present study, the efficacy of the intravenous infusion of an autologous genetically-enriched leucoconcentrate simultaneously producing recombinant vascular endothelial growth factor (VEGF), glial cell line-derived neurotrophic factor (GDNF), and neural cell adhesion molecule (NCAM) was evaluated with regard to the molecular and cellular changes in remodeling of the spinal cord tissue at the site of damage in a model of mini-pigs with moderate spinal cord injury. Experimental animals were randomly divided into two groups of 4 pigs each: the therapeutic (infused with the leucoconcentrate simultaneously transduced with a combination of the three chimeric adenoviral vectors Ad5/35‐VEGF165, Ad5/35‐GDNF, and Ad5/35‐NCAM1) and control groups (infused with intact leucoconcentrate). The morphometric and immunofluorescence analysis of the spinal cord regeneration in the rostral and caudal segments according to the epicenter of the injury in the treated animals compared to the control mini-pigs showed: (1) higher sparing of the grey matter and increased survivability of the spinal cord cells (lower number of Caspase-3-positive cells and decreased expression of Hsp27); (2) recovery of synaptophysin expression; (3) prevention of astrogliosis (lower area of glial fibrillary acidic protein-positive astrocytes and ionized calcium binding adaptor molecule 1-positive microglial cells); (4) higher growth rates of regenerating βIII-tubulin-positive axons accompanied by a higher number of oligodendrocyte transcription factor 2-positive oligodendroglial cells in the lateral corticospinal tract region. These results revealed the efficacy of intravenous infusion of the autologous genetically-enriched leucoconcentrate producing recombinant VEGF, GDNF, and NCAM in the acute phase of spinal cord injury on the positive changes in the post-traumatic remodeling nervous tissue at the site of direct injury. Our data provide a solid platform for a new ex vivo gene therapy for spinal cord injury and will facilitate further translation of regenerative therapies in clinical neurology.
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    Upregulation of CDGSH iron sulfur domain 2 attenuates cerebral ischemia/reperfusion injury
    Miao Hu, Jie Huang, Lei Chen, Xiao-Rong Sun, Zi-Meng Yao, Xu-Hui Tong, Wen-Jing Jin, Yu-Xin Zhang, Shu-Ying Dong
    2023, 18 (7):  1512-1520.  doi: 10.4103/1673-5374.355766
    Abstract ( 151 )   PDF (30655KB) ( 60 )   Save
    CDGSH iron sulfur domain 2 can inhibit ferroptosis, which has been associated with cerebral ischemia/reperfusion, in individuals with head and neck cancer. Therefore, CDGSH iron sulfur domain 2 may be implicated in cerebral ischemia/reperfusion injury. To validate this hypothesis in the present study, we established mouse models of occlusion of the middle cerebral artery and HT22 cell models of oxygen-glucose deprivation and reoxygenation to mimic cerebral ischemia/reperfusion injury in vivo and in vitro, respectively. We found remarkably decreased CDGSH iron sulfur domain 2 expression in the mouse brain tissue and HT22 cells. When we used adeno-associated virus and plasmid to up-regulate CDGSH iron sulfur domain 2 expression in the brain tissue and HT22 cell models separately, mouse neurological dysfunction was greatly improved; the cerebral infarct volume was reduced; the survival rate of HT22 cells was increased; HT22 cell injury was alleviated; the expression of ferroptosis-related glutathione peroxidase 4, cystine-glutamate antiporter, and glutathione was increased; the levels of malondialdehyde, iron ions, and the expression of transferrin receptor 1 were decreased; and the expression of nuclear-factor E2-related factor 2/heme oxygenase 1 was increased. Inhibition of CDGSH iron sulfur domain 2 upregulation via the nuclear-factor E2-related factor 2 inhibitor ML385 in oxygen-glucose deprived and reoxygenated HT22 cells blocked the neuroprotective effects of CDGSH iron sulfur domain 2 up-regulation and the activation of the nuclear-factor E2-related factor 2/heme oxygenase 1 pathway. Our data indicate that the up-regulation of CDGSH iron sulfur domain 2 can attenuate cerebral ischemia/reperfusion injury, thus providing theoretical support from the perspectives of cytology and experimental zoology for the use of this protein as a therapeutic target in patients with cerebral ischemia/reperfusion injury.
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    Transient neurogenesis in ischemic cortex from Sox2+ astrocytes
    Jia-Lei Yang, Hong Fan, Fan-Fan Fu, Bao-Lin Guo, Ying Huang, Li Sun, Wen-Ting Wang, Jun-Ling Xing, Xin-Tian Hu, Yu-Qiang Ding, Kun Zhang, Ying-Zhou Hu, Ya-Zhou Wang
    2023, 18 (7):  1521-1526.  doi: 10.4103/1673-5374.357910
    Abstract ( 156 )   PDF (8581KB) ( 53 )   Save
    The adult cortex has long been regarded as non-neurogenic. Whether injury can induce neurogenesis in the adult cortex is still controversial. Here, we report that focal ischemia stimulates a transient wave of local neurogenesis. Using 5′-bromo-2′-deoxyuridine labeling, we demonstrated a rapid generation of doublecortin-positive neuroblasts that died quickly in mouse cerebral cortex following ischemia. Nestin-CreER-based cell ablation and fate mapping showed a small contribution of neuroblasts by subventricular zone neural stem cells. Using a mini-photothrombotic ischemia mouse model and retrovirus expressing green fluorescent protein labeling, we observed maturation of locally generated new neurons. Furthermore, fate tracing analyses using PDGFRα-, GFAP-, and Sox2-CreER mice showed a transient wave of neuroblast generation in mild ischemic cortex and identified that Sox2-positive astrocytes were the major neurogenic cells in adult cortex. In addition, a similar upregulation of Sox2 and appearance of neuroblasts were observed in the focal ischemic cortex of Macaca mulatta. Our findings demonstrated a transient neurogenic response of Sox2-positive astrocytes in ischemic cortex, which suggests the possibility of inducing neuronal regeneration by amplifying this intrinsic response in the future.  
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    A candidate protective factor in amyotrophic lateral sclerosis: heterogenous nuclear ribonucleoprotein G
    Fang Yang, Wen-Zhi Chen, Shi-Shi Jiang, Xiao-Hua Wang, Ren-Shi Xu
    2023, 18 (7):  1527-1534.  doi: 10.4103/1673-5374.357916
    Abstract ( 131 )   PDF (2925KB) ( 99 )   Save
    Heterogenous nuclear ribonucleoprotein G is down-regulated in the spinal cord of the Tg(SOD1*G93A)1Gur (TG) amyotrophic lateral sclerosis mouse model. However, most studies have only examined heterogenous nuclear ribonucleoprotein G expression in the amyotrophic lateral sclerosis model and heterogenous nuclear ribonucleoprotein G effects in amyotrophic lateral sclerosis pathogenesis such as in apoptosis are unknown. In this study, we studied the potential mechanism of heterogenous nuclear ribonucleoprotein G in neuronal death in the spinal cord of TG and wild-type mice and examined the mechanism by which heterogenous nuclear ribonucleoprotein G induces apoptosis. Heterogenous nuclear ribonucleoprotein G in spinal cord was analyzed using immunohistochemistry and western blotting, and cell proliferation and proteins (TAR DNA binding protein 43, superoxide dismutase 1, and Bax) were detected by the Cell Counting Kit-8 and western blot analysis in heterogenous nuclear ribonucleoprotein G siRNA-transfected PC12 cells. We analyzed heterogenous nuclear ribonucleoprotein G distribution in spinal cord in the amyotrophic lateral sclerosis model at various time points and the expressions of apoptosis and proliferation-related proteins. Heterogenous nuclear ribonucleoprotein G was mainly localized in neurons. Amyotrophic lateral sclerosis mice were examined at three stages: preonset (60–70 days), onset (90–100 days) and progression (120–130 days). The number of heterogenous nuclear ribonucleoprotein G-positive cells was significantly higher in the anterior horn of the lumbar spinal cord segment of TG mice at the preonset stage than that of control group but lower than that of the control group at the onset stage. The number of heterogenous nuclear ribonucleoprotein G-positive cells in both central canal and surrounding gray matter of the whole spinal cord of TG mice at the onset stage was significantly lower than that in the control group, whereas that of the lumbar spinal cord segment of TG mice was significantly higher than that in the control group at preonset stage and significantly lower than that in the control group at the progression stage. The numbers of heterogenous nuclear ribonucleoprotein G-positive cells in the posterior horn of cervical and thoracic segments of TG mice at preonset and progression stages were significantly lower than those in the control group. The expression of heterogenous nuclear ribonucleoprotein G in the cervical spinal cord segment of TG mice was significantly higher than that in the control group at the preonset stage but significantly lower at the progression stage. The expression of heterogenous nuclear ribonucleoprotein G in the thoracic spinal cord segment of TG mice was significantly increased at the preonset stage, significantly decreased at the onset stage, and significantly increased at the progression stage compared with the control group. heterogenous nuclear ribonucleoprotein G expression in the lumbar spinal cord segment of TG mice was significantly lower than that of the control group at the progression stage. After heterogenous nuclear ribonucleoprotein G gene silencing, PC12 cell survival was lower than that of control cells. Both TAR DNA binding protein 43 and Bax expressions were significantly increased in heterogenous nuclear ribonucleoprotein G-silenced cells compared with control cells. Our study suggests that abnormal distribution and expression of heterogenous nuclear ribonucleoprotein G might play a protective effect in amyotrophic lateral sclerosis development via preventing neuronal death by reducing abnormal TAR DNA binding protein 43 generation in the spinal cord.
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    Emodin attenuates inflammation and demyelination in experimental autoimmune encephalomyelitis
    Yue-Ran Cui, Zhong-Qi Bu, Hai-Yang Yu, Li-Li Yan, Juan Feng
    2023, 18 (7):  1535-1541.  doi: 10.4103/1673-5374.358612
    Abstract ( 166 )   PDF (2832KB) ( 77 )   Save
    Emodin, a substance extracted from herbs such as rhubarb, has a protective effect on the central nervous system. However, the potential therapeutic effect of emodin in the context of multiple sclerosis remains unknown. In this study, a rat model of experimental autoimmune encephalomyelitis was established by immune induction to simulate multiple sclerosis, and the rats were intraperitoneally injected with emodin (20 mg/kg/d) from the day of immune induction until they were sacrificed. In this model, the nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and the microglia exacerbated neuroinflammation, playing an important role in the development of multiple sclerosis. In addition, silent information regulator of transcription 1 (SIRT1)/peroxisome proliferator-activated receptor-alpha coactivator (PGC-1α) was found to inhibit activation of the NLRP3 inflammasome, and SIRT1 activation reduced disease severity in experimental autoimmune encephalomyelitis. Furthermore, treatment with emodin decreased body weight loss and neurobehavioral deficits, alleviated inflammatory cell infiltration and demyelination, reduced the expression of inflammatory cytokines, inhibited microglial aggregation and activation, decreased the levels of NLRP3 signaling pathway molecules, and increased the expression of SIRT1 and PGC-1α. These findings suggest that emodin improves the symptoms of experimental autoimmune encephalomyelitis, possibly through regulating the SIRT1/PGC-1α/NLRP3 signaling pathway and inhibiting microglial inflammation. These findings provide experimental evidence for treatment of multiple sclerosis with emodin, enlarging the scope of clinical application for emodin. 
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    The default mode network is affected in the early stage of simian immunodeficiency virus infection: a longitudinal study#br#
    Zhen-Chao Tang, Jiao-Jiao Liu, Xue-Tong Ding, Dan Liu, Hong-Wei Qiao, Xiao-Jie Huang, Hui Zhang, Jie Tian, Hong-Jun Li
    2023, 18 (7):  1542-1547.  doi: 10.4103/1673-5374.360244
    Abstract ( 140 )   PDF (3208KB) ( 26 )   Save
    Acquired immune deficiency syndrome infection can lead to cognitive dysfunction represented by changes in the default mode network. Most recent studies have been cross-sectional and thus have not revealed dynamic changes in the default mode network following acquired immune deficiency syndrome infection and antiretroviral therapy. Specifically, when brain imaging data at only one time point are analyzed, determining the duration at which the default mode network is the most effective following antiretroviral therapy after the occurrence of acquired immune deficiency syndrome. However, because infection times and other factors are often uncertain, longitudinal studies cannot be conducted directly in the clinic. Therefore, in this study, we performed a longitudinal study on the dynamic changes in the default mode network over time in a rhesus monkey model of simian immunodeficiency virus infection. We found marked changes in default mode network connectivity in 11 pairs of regions of interest at baseline and 10 days and 4 weeks after virus inoculation. Significant interactions between treatment and time were observed in the default mode network connectivity of regions of interest pairs area 31/V6.R and area 8/frontal eye field (FEF). L, area 8/FEF.L and caudal temporal parietal occipital area (TPOC).R, and area 31/V6.R and TPOC.L. ART administered 4 weeks after infection not only interrupted the progress of simian immunodeficiency virus infection but also preserved brain function to a large extent. These findings suggest that the default mode network is affected in the early stage of simian immunodeficiency virus infection and that it may serve as a potential biomarker for early changes in brain function and an objective indicator for making early clinical intervention decisions.
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    Inhibition of autophagy rescues HT22 hippocampal neurons from erastin-induced ferroptosis
    Nora Hanke, Abdelhaq Rami
    2023, 18 (7):  1548-1552.  doi: 10.4103/1673-5374.360246
    Abstract ( 233 )   PDF (3013KB) ( 68 )   Save
    Ferroptosis is a regulated form of cell death which is considered an oxidative iron-dependent process. The lipid hydroperoxidase glutathione peroxidase 4 prevents the iron (Fe2+)-dependent formation of toxic lipid reactive oxygen species. While emerging evidence indicates that inhibition of glutathione peroxidase 4 as a hallmark of ferroptosis in many cancer cell lines, the involvement of this biochemical pathway in neuronal death remains largely unclear. Here, we investigate, first whether the ferroptosis key players are involved in the neuronal cell death induced by erastin. The second objective was to examine whether there is a cross talk between ferroptosis and autophagy. The third main was to address neuron response to erastin, with a special focus on ferritin and nuclear receptor coactivator 4-mediated ferritinophagy. To test this in neurons, erastin (0.5–8 µM) was applied to hippocampal HT22 neurons for 16 hours. In addition, cells were cultured with the autophagy inhibitor, 3-methyladenin (10 mM) and/or ferroptosis inhibitors, ferrostatin 1 (10–20 µM) or deferoxamine (10–200 µM) before exposure to erastin. In this study, we demonstrated by immunofluorescence and western blot analysis, that erastin downregulates dramatically the expression of glutathione peroxidase 4, the sodium-independent cystine-glutamate antiporter and nuclear receptor coactivator 4. The protein levels of ferritin and mitochondrial ferritin in HT22 hippocampal neurons did not remarkably change following erastin treatment. In addition, we demonstrated that not only the ferroptosis inhibitor, ferrostatin1/deferoxamine abrogated the ferroptotic cell death induced by erastin in hippocampal HT22 neurons, but also the potent autophagy inhibitor, 3-methyladenin. We conclude that (1) erastin-induced ferroptosis in hippocampal HT22 neurons, despite reduced nuclear receptor coactivator 4 levels, (2) that either nuclear receptor coactivator 4-mediated ferritinophagy does not occur or is of secondary importance in this model, (3) that ferroptosis seems to share some features of the autophagic cell death process.
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    Metformin promotes angiogenesis and functional recovery in aged mice after spinal cord injury by adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway
    Jin-Yun Zhao, Xiao-Long Sheng, Cheng-Jun Li, Tian Qin, Run-Dong He, Guo-Yu Dai, Yong Cao, Hong-Bin Lu, Chun-Yue Duan, Jian-Zhong Hu
    2023, 18 (7):  1553-1562.  doi: 10.4103/1673-5374.360245
    Abstract ( 216 )   PDF (12088KB) ( 81 )   Save
    Treatment with metformin can lead to the recovery of pleiotropic biological activities after spinal cord injury. However, its effect on spinal cord injury in aged mice remains unclear. Considering the essential role of angiogenesis during the regeneration process, we hypothesized that metformin activates the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway in endothelial cells, thereby promoting microvascular regeneration in aged mice after spinal cord injury. In this study, we established young and aged mouse models of contusive spinal cord injury using a modified Allen method. We found that aging hindered the recovery of neurological function and the formation of blood vessels in the spinal cord. Treatment with metformin promoted spinal cord microvascular endothelial cell migration and blood vessel formation in vitro. Furthermore, intraperitoneal injection of metformin in an in vivo model promoted endothelial cell proliferation and increased the density of new blood vessels in the spinal cord, thereby improving neurological function. The role of metformin was reversed by compound C, an adenosine monophosphate-activated protein kinase inhibitor, both in vivo and in vitro, suggesting that the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway likely regulates metformin-mediated angiogenesis after spinal cord injury. These findings suggest that metformin promotes vascular regeneration in the injured spinal cord by activating the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway, thereby improving the neurological function of aged mice after spinal cord injury. 
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    Magnetic resonance imaging focused on the ferritin heavy chain 1 reporter gene detects neuronal differentiation in stem cells
    Xiao-Ya He, Yi-Rui Zhou, Tong Mu, Yi-Fan Liao, Li Jiang, Yong Qin, Jin-Hua Cai
    2023, 18 (7):  1563-1569.  doi: 10.4103/1673-5374.358608
    Abstract ( 132 )   PDF (4371KB) ( 104 )   Save
    The neuronal differentiation of mesenchymal stem cells offers a new strategy for the treatment of neurological disorders. Thus, there is a need to identify a noninvasive and sensitive in vivo imaging approach for real-time monitoring of transplanted stem cells. Our previous study confirmed that magnetic resonance imaging, with a focus on the ferritin heavy chain 1 reporter gene, could track the proliferation and differentiation of bone marrow mesenchymal stem cells that had been transduced with lentivirus carrying the ferritin heavy chain 1 reporter gene. However, we could not determine whether or when bone marrow mesenchymal stem cells had undergone neuronal differentiation based on changes in the magnetic resonance imaging signal. To solve this problem, we identified a neuron-specific enolase that can be differentially expressed before and after neuronal differentiation in stem cells. In this study, we successfully constructed a lentivirus carrying the neuron-specific enolase promoter and expressing the ferritin heavy chain 1 reporter gene; we used this lentivirus to transduce bone marrow mesenchymal stem cells. Cellular and animal studies showed that the neuron-specific enolase promoter effectively drove the expression of ferritin heavy chain 1 after neuronal differentiation of bone marrow mesenchymal stem cells; this led to intracellular accumulation of iron and corresponding changes in the magnetic resonance imaging signal. In summary, we established an innovative magnetic resonance imaging approach focused on the induction of reporter gene expression by a neuron-specific promoter. This imaging method can be used to noninvasively and sensitively detect neuronal differentiation in stem cells, which may be useful in stem cell-based therapies.
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    L- and T-type Ca2+ channels dichotomously contribute to retinal ganglion cell injury in experimental glaucoma
    Hong-Ning Wang, Wen-Jing Qian, Guo-Li Zhao, Fang Li, Yan-Ying Miao, Bo Lei, Xing-Huai Sun, Zhong-Feng Wang
    2023, 18 (7):  1570-1577.  doi: 10.4103/1673-5374.360277
    Abstract ( 174 )   PDF (3075KB) ( 49 )   Save

    Retinal ganglion cell apoptotic death is the main pathological characteristic of glaucoma, which is the leading cause of irreversible blindness. Disruption of Ca2+ homeostasis plays an important role in glaucoma. Voltage-gated Ca2+ channel blockers have been shown to improve vision in patients with glaucoma. However, whether and how voltage-gated Ca2+ channels are involved in retinal ganglion cell apoptotic death are largely unknown. In this study, we found that total Ca2+ current densities in retinal ganglion cells were reduced in a rat model of chronic ocular hypertension experimental glaucoma, as determined by whole-cell patch-clamp electrophysiological recordings. Further analysis showed that L-type Ca2+ currents were downregulated while T-type Ca2+ currents were upregulated at the later stage of glaucoma. Western blot assay and immunofluorescence experiments confirmed that expression of the CaV1.2 subunit of L-type Ca2+ channels was reduced and expression of the CaV3.3 subunit of T-type Ca2+ channels was increased in retinas of the chronic ocular hypertension model. Soluble tumor necrosis factor-α, an important inflammatory factor, inhibited the L-type Ca2+ current of isolated retinal ganglion cells from control rats and enhanced the T-type Ca2+ current. These changes were blocked by the tumor necrosis factor-α inhibitor XPro1595, indicating that both types of Ca2+ currents may be mediated by soluble tumor necrosis factor-α. The intracellular mitogen-activated protein kinase/extracellular signal-regulated kinase pathway and nuclear factor kappa-B signaling pathway mediate the effects of tumor necrosis factor-α. TUNEL assays revealed that mibefradil, a T-type calcium channel blocker, reduced the number of apoptotic retinal ganglion cells in the rat model of chronic ocular hypertension. These results suggest that T-type Ca2+ channels are involved in disrupted Ca2+ homeostasis and apoptosis of retinal ganglion cells in glaucoma, and application of T-type Ca2+ channel blockers, especially a specific CaV3.3 blocker, may be a potential strategy for the treatment of glaucoma. 

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    Inhibiting phosphatase and actin regulator 1 expression is neuroprotective in the context of traumatic brain injury
    Yao Jing, Lin Zhang, Shi-Wen Chen, Yan Guo, Shi-Ming Ju, Fang Yuan, Hao Chen, Dian-Xu Yang, Heng-Li Tian, Zhi-Ming Xu, Jun Ding
    2023, 18 (7):  1578-1583.  doi: 10.4103/1673-5374.357904
    Abstract ( 151 )   PDF (2035KB) ( 65 )   Save
    Studies have found that the phosphatase actin regulatory factor 1 expression can be related to stroke, but it remains unclear whether changes in phosphatase actin regulatory factor 1 expression also play a role in traumatic brain injury. In this study we found that, in a mouse model of traumatic brain injury induced by controlled cortical impact, phosphatase actin regulatory factor 1 expression is increased in endothelial cells, neurons, astrocytes, and microglia. When we overexpressed phosphatase actin regulatory factor 1 by injection an adeno-associated virus vector into the contused area in the traumatic brain injury mice, the water content of the brain tissue increased. However, when phosphatase actin regulatory factor 1 was knocked down, the water content decreased. We also found that inhibiting phosphatase actin regulatory factor 1 expression regulated the nuclear factor kappa B signaling pathway, decreased blood-brain barrier permeability, reduced aquaporin 4 and intercellular adhesion molecule 1 expression, inhibited neuroinflammation, and neuronal apoptosis, thereby improving neurological function. The findings from this study indicate that phosphatase actin regulatory factor 1 may be a potential therapeutic target for traumatic brain injury. 
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    Potential application of let-7a antagomir in injured peripheral nerve regeneration
    Qian-Qian Chen Qian-Yan Liu, Pan Wang, Tian-Mei Qian, Xing-Hui Wang, Sheng Yi, Shi-Ying Li
    2023, 18 (7):  1584-1590.  doi: 10.4103/1673-5374.357914
    Abstract ( 156 )   PDF (3091KB) ( 112 )   Save
    Neurotrophic factors, particularly nerve growth factor, enhance neuronal regeneration. However, the in vivo applications of nerve growth factor are largely limited by its intrinsic disadvantages, such as its short biological half-life, its contribution to pain response, and its inability to cross the blood-brain barrier. Considering that let-7 (human miRNA) targets and regulates nerve growth factor, and that let-7 is a core regulator in peripheral nerve regeneration, we evaluated the possibilities of let-7 application in nerve repair. In this study, anti-let-7a was identified as the most suitable let-7 family molecule by analyses of endogenous expression and regulatory relationship, and functional screening. Let-7a antagomir demonstrated biosafety based on the results of in vivo safety assessments and it entered into the main cell types of the sciatic nerve, including Schwann cells, fibroblasts and macrophages. Use of hydrogel effectively achieved controlled, localized, and sustained delivery of let-7a antagomir. Finally, let-7a antagomir was integrated into chitosan conduit to construct a chitosan-hydrogel scaffold tissue-engineered nerve graft, which promoted nerve regeneration and functional recovery in a rat model of sciatic nerve transection. Our study provides an experimental basis for potential in vivo application of let-7a.
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    The circ_0002538/miR-138-5p/plasmolipin axis regulates Schwann cell migration and myelination in diabetic peripheral neuropathy
    Yu-Tian Liu, Zhao Xu, Wei Liu, Sen Ren, He-Wei Xiong, Tao Jiang, Jing Chen, Yu Kang, Qian-Yun Li, Zi-Han Wu, Hans-GüNther Machens, Xiao-Fan Yang, Zhen-Bing Chen
    2023, 18 (7):  1591-1600.  doi: 10.4103/1673-5374.355979
    Abstract ( 148 )   PDF (6434KB) ( 110 )   Save
    Circular RNAs (circRNAs) play a vital role in diabetic peripheral neuropathy. However, their expression and function in Schwann cells in individuals with diabetic peripheral neuropathy remain poorly understood. Here, we performed protein profiling and circRNA sequencing of sural nerves in patients with diabetic peripheral neuropathy and controls. Protein profiling revealed 265 differentially expressed proteins in the diabetic peripheral neuropathy group. Gene Ontology indicated that differentially expressed proteins were mainly enriched in myelination and mitochondrial oxidative phosphorylation. A real-time polymerase chain reaction assay performed to validate the circRNA sequencing results yielded 11 differentially expressed circRNAs. circ_0002538 was markedly downregulated in patients with diabetic peripheral neuropathy. Further in vitro experiments showed that overexpression of circ_0002538 promoted the migration of Schwann cells by upregulating plasmolipin (PLLP) expression. Moreover, overexpression of circ_0002538 in the sciatic nerve in a streptozotocin-induced mouse model of diabetic peripheral neuropathy alleviated demyelination and improved sciatic nerve function. The results of a mechanistic experiment showed that circ_0002538 promotes PLLP expression by sponging miR-138-5p, while a lack of circ_0002538 led to a PLLP deficiency that further suppressed Schwann cell migration. These findings suggest that the circ_0002538/miR-138-5p/PLLP axis can promote the migration of Schwann cells in diabetic peripheral neuropathy patients, improving myelin sheath structure and nerve function. Thus, this axis is a potential target for therapeutic treatment of diabetic peripheral neuropathy.
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    PTEN inhibitor bisperoxovanadium protects against noise-induced hearing loss
    Bei Fan, Fei Lu, Wei-Jia Du, Jun Chen, Xiao-Gang An, Ren-Feng Wang, Wei Li, Yong-Li Song, Ding-Jun Zha, Fu-Quan Chen
    2023, 18 (7):  1601-1606.  doi: 10.4103/1673-5374.358606
    Abstract ( 127 )   PDF (4930KB) ( 74 )   Save
    Studies have shown that phosphatase and tensin homolog deleted on chromosome ten (PTEN) participates in the regulation of cochlear hair cell survival. Bisperoxovanadium protects against neurodegeneration by inhibiting PTEN expression. However, whether bisperoxovanadium can protect against noise-induced hearing loss and the underlying mechanism remains unclear. In this study, we established a mouse model of noise-induced hearing loss by exposure to 105 dB sound for 2 hours. We found that PTEN expression was increased in the organ of Corti, including outer hair cells, inner hair cells, and lateral wall tissues. Intraperitoneal administration of bisperoxovanadium decreased the auditory threshold and the loss of cochlear hair cells and inner hair cell ribbons. In addition, noise exposure decreased p-PI3K and p-Akt levels. Bisperoxovanadium preconditioning or PTEN knockdown upregulated the activity of PI3K-Akt. Bisperoxovanadium also prevented H2O2-induced hair cell death by reducing mitochondrial reactive oxygen species generation in cochlear explants. These findings suggest that bisperoxovanadium reduces noise-induced hearing injury and reduces cochlear hair cell loss. 
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    Valproate reduces retinal ganglion cell apoptosis in rats after optic nerve crush
    Feng Pan, Dan Hu, Li-Juan Sun, Qian Bai, Yu-Sheng Wang, Xu Hou
    2023, 18 (7):  1607-1612.  doi: 10.4103/1673-5374.357913
    Abstract ( 158 )   PDF (7821KB) ( 56 )   Save
    The retinal ganglion cells of the optic nerve have a limited capacity for self-repair after injury. Valproate is a histone deacetylase inhibitor and multitarget drug, which has been demonstrated to protect retinal neurons. In this study, we established rat models of optic nerve-crush injury and injected valproate into the vitreous cavity immediately after modeling. We evaluated changes in the ultrastructure morphology of the endoplasmic reticulum of retinal ganglion cells over time via transmission electron microscope. Immunohistochemistry and western blot assay revealed that valproate upregulated the expression of the endoplasmic reticulum stress marker glucose-regulated protein 78 and downregulated the expression of transcription factor C/EBP homologous protein, phosphorylated eukaryotic translation initiation factor 2α, and caspase-12 in the endoplasmic reticulum of retinal ganglion cells. These findings suggest that valproate reduces apoptosis of retinal ganglion cells in the rat after optic nerve-crush injury by attenuating phosphorylated eukaryotic translation initiation factor 2α-C/EBP homologous protein signaling and caspase-12 activation during endoplasmic reticulum stress. These findings represent a newly discovered mechanism that regulates how valproate protects neurons.
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    Oncogenic BRAFV600E induces microglial proliferation through extracellular signal-regulated kinase and neuronal death through c-Jun N-terminal kinase
    Qing Ye, Pranay Srivastava, Nasser Al-Kuwari, Xiqun Chen
    2023, 18 (7):  1613-1622.  doi: 10.4103/1673-5374.361516
    Abstract ( 141 )   PDF (7406KB) ( 41 )   Save
    Activating V600E in v-Raf murine sarcoma viral oncogene homolog B (BRAF) is a common driver mutation in cancers of multiple tissue origins, including melanoma and glioma. BRAFV600E has also been implicated in neurodegeneration. The present study aims to characterize BRAFV600E during cell death and proliferation of three major cell types of the central nervous system: neurons, astrocytes, and microglia. Multiple primary cultures (primary cortical mixed culture) and cell lines of glial cells (BV2) and neurons (SH-SY5Y) were employed. BRAFV600E and BRAFWT expression was mediated by lentivirus or retrovirus. Blockage of downstream effectors (extracellular signal-regulated kinase 1/2 and JNK1/2) were achieved by siRNA. In astrocytes and microglia, BRAFV600E induces cell proliferation, and the proliferative effect in microglia is mediated by activated extracellular signal-regulated kinase, but not c-Jun N-terminal kinase. Conditioned medium from BRAFV600E-expressing microglia induced neuronal death. In neuronal cells, BRAFV600E directly induces neuronal death, through c-Jun N-terminal kinase but not extracellular signal-regulated kinase. We further show that BRAF-related genes are enriched in pathways in patients with Parkinson’s disease. Our study identifies distinct consequences mediated by distinct downstream effectors in dividing glial cells and in neurons following the same BRAF mutational activation and a causal link between BRAF-activated microglia and neuronal cell death that does not require physical proximity. It provides insight into a possibly important role of BRAF in neurodegeneration as a result of either dysregulated BRAF in neurons or its impact on glial cells.
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    High-dose biotin neither fosters remyelination nor stimulates malonyl coenzyme A synthesis in the regenerating nerve#br#
    Fabian Szepanowski, Rebecca D. Steubing, Cansu Güngör, Jaqueline Zipfel, Anne K. Mausberg, Christoph Kleinschnitz, Mark Stettner
    2023, 18 (7):  1623-1624.  doi: 10.4103/1673-5374.361542
    Abstract ( 122 )   PDF (493KB) ( 38 )   Save
    Dear editor,
    Dysregulated inflammatory responses primarily account for damage to the central nervous system, however, neurodegenerative processes likely contribute to the pathophysiology of progressive forms of multiple sclerosis (MS). These pathophysiological aspects include axonal energy depletion and impaired remyelination capacity (Levin et al., 2014). The clinical efficacy of most disease-modifying therapies in MS to date has been achieved by targeting functions of the adaptive immune system (Cree et al., 2019; Szepanowski et al., 2021). In light of the unmet need for a regenerative therapy in multiple sclerosis, the concept of high-dose biotin (HDB) treatment (approximately 10,000-fold the recommended daily allowance) as a neurometabolic modulator arose (Sedel et al., 2016). Biotin is an essential cofactor for five carboxylase enzymes: pyruvate carboxylase, propionyl-coenzyme A (CoA) carboxylase, 3-methylcrotonyl-CoA carboxylase and two isoforms of acetyl-CoA carboxylase (ACC), ACC-265 and ACC-280 (Zempleni and Kuroishi, 2012). Given the involvement of these carboxylases in a wide range of metabolic pathways, it has been hypothesized that supraphysiological doses of biotin might have neuroprotective and regenerative potential. For example, HDB might contribute to adenosine triphosphate production by increasing intermediates of the tricarboxylic acid cycle and may improve remyelination by elevating levels of the ACC product, malonyl-CoA, as a building block for fatty acid synthesis (Sedel et al., 2016). However, these claims regarding the presumptive mode of action of HDB have barely been validated in preclinical studies employing appropriate animal models. Nevertheless, an open-label pilot study investigating the efficacy of HDB in patients with primary and secondary progressive MS revealed promising results (Sedel et al., 2015). A randomized, double-blind, placebo controlled study (MS-SPI) indicated that HDB might reverse disability in a subgroup of progressive MS patients compared to the placebo arm (Tourbah et al., 2016). Despite these initial positive results, the subsequent phase 3 trial (SPI2) did not show significant improvements of disability, leading to the conclusion that HDB cannot be recommended for patients with progressive forms of MS (Cree et al., 2020). 
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