Astrocyte function and role in motor neuron disease: A future therapeutic target?

Sleep deprivation in adolescent mice impairs long-term memory till early adulthood via suppression of hippocampal astrocytes

Sleep deficiency is a rampant issue in modern society, serving as a pathogenic element contributing to learning and memory impairment, with heightened sensitivity observed in children. Clinical observations suggest that learning disabilities associated with insufficient sleep during adolescence can persist through adulthood, but experimental evidence for this is lacking. In this study, we examined the impact of early-life sleep deprivation (SD) on both short-term and long-term memory, tracking the effects sequentially into adulthood. We employed a modified multiple-platform method mouse model to investigate these outcomes. SD induced over a 14-day period, beginning on postnatal day 28 (PND28) in mice, led to significant impairment in long-term memory (while short-term memory remained unaffected) at PND42. Notably, this dysfunction persisted into adulthood at PND85. The specific impairment observed in long-term memory was elucidated through histopathological alterations in hippocampal neurogenesis, as evidenced by bromodeoxyuridine (BrdU) signals, observed both at PND42 and PND85. Furthermore, the hippocampal region exhibited significantly diminished protein expressions of astrocytes, characterized by lowered levels of aquaporin 4 (AQP4), a representative molecule involved in brain clearance processes, and reduced protein expressions of brain-derived neurotrophic factors. In conclusion, we have presented experimental evidence indicating that sleep deficiency-related impairment of long-term memory in adolescence can endure into adulthood. The corresponding mechanisms may indicate that the modification of astrocyte-related molecules has led to changes in hippocampal neurogenesis.

Differential Susceptibility to Propofol and Ketamine in Primary Cultures of Young and Senesced Astrocytes

The adverse effects of general anesthesia on the long-term cognition of young children and senior adults have become of concern in recent years. Previously, mechanistic and pathogenic investigations focused on neurons, and little is known about the effect of commonly used intravenous anesthetics such as propofol and ketamine on astrocytes. Recently, astrocyte dysfunction has been implicated in a wide range of age-related brain diseases. In this study, we examined the survival and viability of both young and senescent astrocytes in culture after adding propofol and ketamine to the media at varying strengths. Oxidative stimulus was applied to commercially available fetal cell lines of human astrocytes in vitro to induce morphological changes in cellular senescence. Our results indicate that propofol reduces the survival of young astrocytes as compared to controls, as well as to ketamine. These effects were seen in comparisons of total cell count and at both high and low dose concentrations. High doses of propofol also significantly reduced cell viability compared to those exposed to baseline controls and ketamine. Senescent astrocytes, on the other hand, demonstrated cell count reductions as compared to baseline controls and ketamine when exposed to either DMSO or propofol. The data show differential susceptibility of young astrocytes to propofol than to ketamine. The observed cell count reduction may be related to the adverse effects of propofol on mitochondrial function and free radical production, as described in previous studies. We speculate that ketamine may have a more favorable safety profile in infants and young children.

The Interplay between Ferroptosis and Neuroinflammation in Central Neurological Disorders

Central neurological disorders are significant contributors to morbidity, mortality, and long-term disability globally in modern society. These encompass neurodegenerative diseases, ischemic brain diseases, traumatic brain injury, epilepsy, depression, and more. The involved pathogenesis is notably intricate and diverse. Ferroptosis and neuroinflammation play pivotal roles in elucidating the causes of cognitive impairment stemming from these diseases. Given the concurrent occurrence of ferroptosis and neuroinflammation due to metabolic shifts such as iron and ROS, as well as their critical roles in central nervous disorders, the investigation into the co-regulatory mechanism of ferroptosis and neuroinflammation has emerged as a prominent area of research. This paper delves into the mechanisms of ferroptosis and neuroinflammation in central nervous disorders, along with their interrelationship. It specifically emphasizes the core molecules within the shared pathways governing ferroptosis and neuroinflammation, including SIRT1, Nrf2, NF-κB, Cox-2, iNOS/NO·, and how different immune cells and structures contribute to cognitive dysfunction through these mechanisms. Researchers' findings suggest that ferroptosis and neuroinflammation mutually promote each other and may represent key factors in the progression of central neurological disorders. A deeper comprehension of the common pathway between cellular ferroptosis and neuroinflammation holds promise for improving symptoms and prognosis related to central neurological disorders.

Updates of the role of B-cells in ischemic stroke

Ischemic stroke is a major disease causing death and disability in the elderly and is one of the major diseases that seriously threaten human health and cause a great economic burden. In the early stage of ischemic stroke, neuronal structure is destroyed, resulting in death or damage, and the release of a variety of damage-associated pattern molecules induces an increase in neuroglial activation, peripheral immune response, and secretion of inflammatory mediators, which further exacerbates the damage to the blood-brain barrier, exacerbates cerebral edema, and microcirculatory impairment, triggering secondary brain injuries. After the acute phase of stroke, various immune cells initiate a protective effect, which is released step by step and contributes to the repair of neuronal cells through phenotypic changes. In addition, ischemic stroke induces Central Nervous System (CNS) immunosuppression, and the interaction between the two influences the outcome of stroke. Therefore, modulating the immune response of the CNS to reduce the inflammatory response and immune damage during stroke is important for the protection of brain function and long-term recovery after stroke, and modulating the immune function of the CNS is expected to be a novel therapeutic strategy. However, there are fewer studies on B-cells in brain function protection, which may play a dual role in the stroke process, and the understanding of this cell is still incomplete. We review the existing studies on the mechanisms of the role of B-cells, inflammatory response, and immune response in the development of ischemic stroke and provide a reference for the development of adjuvant therapeutic drugs for ischemic stroke targeting inflammatory injury.

Functionalized ZnO-Based Nanocomposites for Diverse Biological Applications: Current Trends and Future Perspectives

The wide array of structures and characteristics found in ZnO-based nanostructures offers them a versatile range of uses. Over the past decade, significant attention has been drawn to the possible applications of these materials in the biomedical field, owing to their distinctive electronic, optical, catalytic, and antimicrobial attributes, alongside their exceptional biocompatibility and surface chemistry. With environmental degradation and an aging population contributing to escalating healthcare needs and costs, particularly in developing nations, there's a growing demand for more effective and affordable biomedical devices with innovative functionalities. This review delves into particular essential facets of different synthetic approaches (chemical and green) that contribute to the production of effective multifunctional nano-ZnO particles for biomedical applications. Outlining the conjugation of ZnO nanoparticles highlights the enhancement of biomedical capacity while lowering toxicity. Additionally, recent progress in the study of ZnO-based nano-biomaterials tailored for biomedical purposes is explored, including biosensing, bioimaging, tissue regeneration, drug delivery, as well as vaccines and immunotherapy. The final section focuses on nano-ZnO particles' toxicity mechanism with special emphasis to their neurotoxic potential, as well as the primary toxicity pathways, providing an overall review of the up-to-date development and future perspectives of nano-ZnO particles in the biomedicine field.

Therapeutic Effects of Combination of Nebivolol and Donepezil: Targeting Multifactorial Mechanisms in ALS

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive loss of motor neurons in the spinal cord. Although the disease's pathophysiological mechanism remains poorly understood, multifactorial mechanisms affecting motor neuron loss converge to worsen the disease. Although two FDA-approved drugs, riluzole and edaravone, targeting excitotoxicity and oxidative stress, respectively, are available, their efficacies are limited to extending survival by only a few months. Here, we developed combinatorial drugs targeting multifactorial mechanisms underlying key components in ALS disease progression. Using data analysis based on the genetic information of patients with ALS-derived cells and pharmacogenomic data of the drugs, a combination of nebivolol and donepezil (nebivolol-donepezil) was identified for ALS therapy. Here, nebivolol-donepezil markedly reduced the levels of cytokines in the microglial cell line, inhibited nuclear factor-κB (NF-κB) nucleus translocation in the HeLa cell and substantially protected against excitotoxicity-induced neuronal loss by regulating the PI3K-Akt pathway. Nebivolol-donepezil significantly promoted the differentiation of neural progenitor cells (NPC) into motor neurons. Furthermore, we verified the low dose efficacy of nebivolol-donepezil on multiple indices corresponding to the quality of life of patients with ALS in vivo using SOD1G93A mice. Nebivolol-donepezil delayed motor function deterioration and halted motor neuronal loss in the spinal cord. Drug administration effectively suppressed muscle atrophy by mitigating the proportion of smaller myofibers and substantially reducing phospho-neurofilament heavy chain (pNF-H) levels in the serum, a promising ALS biomarker. High-dose nebivolol-donepezil significantly prolonged survival and delayed disease onset compared with vehicle-treated mice. These results indicate that the combination of nebivolol-donepezil efficiently prevents ALS disease progression, benefiting the patients' quality of life and life expectancy.

Causal ALS genes impact the MHC class II antigen presentation pathway

Mutations in RNA/DNA-binding proteins cause amyotrophic lateral sclerosis (ALS), but the underlying disease mechanisms remain unclear. Here, we report that a set of ALS-associated proteins, namely FUS, EWSR1, TAF15, and MATR3, impact the expression of genes encoding the major histocompatibility complex II (MHC II) antigen presentation pathway. Both subunits of the MHC II heterodimer, HLA-DR, are down-regulated in ALS gene knockouts/knockdown in HeLa and human microglial cells, due to loss of the MHC II transcription factor CIITA. Importantly, hematopoietic progenitor cells (HPCs) derived from human embryonic stem cells bearing the FUSR495X mutation and HPCs derived from C9ORF72 ALS patient induced pluripotent stem cells also exhibit disrupted MHC II expression. Given that HPCs give rise to numerous immune cells, our data raise the possibility that loss of the MHC II pathway results in global failure of the immune system to protect motor neurons from damage that leads to ALS.

Current evidence, clinical applications, and future directions of transcranial magnetic stimulation as a treatment for ischemic stroke

Transcranial magnetic stimulation (TMS) is a non-invasive brain neurostimulation technique that can be used as one of the adjunctive treatment techniques for neurological recovery after stroke. Animal studies have shown that TMS treatment of rats with middle cerebral artery occlusion (MCAO) model reduced cerebral infarct volume and improved neurological dysfunction in model rats. In addition, clinical case reports have also shown that TMS treatment has positive neuroprotective effects in stroke patients, improving a variety of post-stroke neurological deficits such as motor function, swallowing, cognitive function, speech function, central post-stroke pain, spasticity, and other post-stroke sequelae. However, even though numerous studies have shown a neuroprotective effect of TMS in stroke patients, its possible neuroprotective mechanism is not clear. Therefore, in this review, we describe the potential mechanisms of TMS to improve neurological function in terms of neurogenesis, angiogenesis, anti-inflammation, antioxidant, and anti-apoptosis, and provide insight into the current clinical application of TMS in multiple neurological dysfunctions in stroke. Finally, some of the current challenges faced by TMS are summarized and some suggestions for its future research directions are made.

The Effect of Interleukin-1 Antagonists on Brain Volume and Cognitive Function in Two Patients With Megalencephalic Leukoencephalopathy With Subcortical Cysts

BACKGROUND

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare leukodystrophy characterized by early-onset macrocephaly and progressive white matter vacuolation. The MLC1 protein plays a role in astrocyte activation during neuroinflammation and regulates volume decrease following astrocyte osmotic swelling. Loss of MLC1 function activates interleukin (IL)-1β-induced inflammatory signals. Theoretically, IL-1 antagonists (such as anakinra and canakinumab) can slow the progression of MLC. Herein, we present two boys from different families who had MLC due to biallelic MLC1 gene mutations and were treated with the anti-IL-1 drug anakinra.

METHODS

Two boys from different families presented with megalencephaly and psychomotor retardation. Brain magnetic resonance imaging findings in both patients were compatible with the diagnosis of MLC. The diagnosis of MLC was confirmed via Sanger analysis of the MLC1 gene. Anakinra was administered to both patients. Volumetric brain studies and psychometric evaluations were performed before and after anakinra treatment.

RESULTS

After anakinra therapy, brain volume in both patients decreased significantly and cognitive functions and social interactions improved. No adverse effects were observed during anakinra therapy.

CONCLUSIONS

Anakinra or other IL-1 antagonists can be used to suppress disease activity in patients with MLC; however, the present findings need to be confirmed via additional research.

Senescent cells in the brain and where to find them

Cellular senescence is a process in which cells change their characteristic phenotype in response to stress and enter a state of prolonged cell cycle arrest accompanied by a distinct secretory phenotype. Cellular senescence has both beneficial and detrimental outcomes. With age, senescent cells progressively accumulate in tissues and might be the bridge connecting ageing to many age-related pathologies. In recent years, evidence emerged supporting the accumulation of brain senescent cells during neurological disorders and ageing. Here, we will discuss the different brain cell populations that exhibit a senescent phenotype. Subsequently, we will explore several senolytic strategies which have been developed to eliminate senescent cells. Finally, we will examine their potential to directly eliminate these senescent brain cells.

Ashwagandha-loaded nanocapsules improved the behavioral alterations, and blocked MAPK and induced Nrf2 signaling pathways in a hepatic encephalopathy rat model

Ashwagandha (ASH), a vital herb in Ayurvedic medicine, demonstrated potent preclinical hepato- and neuroprotective effects. However, its efficacy is limited due to low oral bioavailability. Accordingly, we encapsulated ASH extract in chitosan-alginate bipolymeric nanocapsules (ASH-BPNCs) to enhance its physical stability and therapeutic effectiveness in the gastrointestinal tract. ASH-BPNC was prepared by emulsification followed by sonication. The NCs showed small particle size (< 220 nm), zeta-potential of 25.2 mV, relatively high entrapment efficiency (79%), physical stability at acidic and neutral pH, and in vitro release profile that extended over 48 h. ASH-BPNC was then investigated in a thioacetamide-induced hepatic encephalopathy (HE) rat model. Compared with free ASH, ASH-BPNC improved survival, neurological score, general motor activity, and cognitive task-performance. ASH-BPNC restored ALT, AST and ammonia serum levels, and maintained hepatic and brain architecture. ASH-BPNC also restored GSH, MDA, and glutathione synthetase levels, and Nrf2 and MAPK signaling pathways in liver and brain tissues. Moreover, ASH-BPNC downregulated hepatic NF-κB immunohistochemical expression. Moreover, the in vivo biodistribution studies demonstrated that most of the administered ASH-BPNC is accumulated in the brain and hepatic tissues. In conclusion, chitosan-alginate BPNCs enhanced the hepatoprotective and neuroprotective effects of ASH, thus providing a promising therapeutic approach for HE.

Mechanisms of IRF2BPL-related disorders and identification of a potential therapeutic strategy

The recently discovered neurological disorder NEDAMSS is caused by heterozygous truncations in the transcriptional regulator IRF2BPL. Here, we reprogram patient skin fibroblasts to astrocytes and neurons to study mechanisms of this newly described disease. While full-length IRF2BPL primarily localizes to the nucleus, truncated patient variants sequester the wild-type protein to the cytoplasm and cause aggregation. Moreover, patient astrocytes fail to support neuronal survival in coculture and exhibit aberrant mitochondria and respiratory dysfunction. Treatment with the small molecule copper ATSM (CuATSM) rescues neuronal survival and restores mitochondrial function. Importantly, the in vitro findings are recapitulated in vivo, where co-expression of full-length and truncated IRF2BPL in Drosophila results in cytoplasmic accumulation of full-length IRF2BPL. Moreover, flies harboring heterozygous truncations of the IRF2BPL ortholog (Pits) display progressive motor defects that are ameliorated by CuATSM treatment. Our findings provide insights into mechanisms involved in NEDAMSS and reveal a promising treatment for this severe disorder.

Novel insights into host responses to Japanese Encephalitis Virus infection: Reanalysis of public transcriptome and microRNAome datasets

PURPOSE

Japanese encephalitis (JE), caused by the Japanese encephalitis virus (JEV), is the principal cause of viral encephalitis in South-East Asian and Western Pacific countries; accounting for 68,000 cases, and up to 20,400 fatalities, annually across the world. Despite being a high-risk condition, there is no specific treatment for JE. Given rapid additions in genomics databases and the power of data reanalysis in addressing critical medical questions, the present study was designed to identify novel host factors that might have potential roles in JEV infection.

METHODS

We extracted microarray and RNA-Seq data sets from NCBI-GEO and compared mock and JEV-infected samples. Raw data from all the studies were re-analyzed to identify host factors associated with JEV replication.

RESULTS

We identified several coding and non-coding host factors that had no prior known role in viral infections. Of these, the coding transcripts: Myosin Heavy Chain 10 (MYH10), Progestin and AdipoQ Receptor Family Member 8 (PAQR8), and the microRNAs: hsa-miR-193b-5p, hsa-miR-3714 and hsa-miR-513a-5p were found to be novel host factors deregulated during JEV infection. MYH10 encodes a conventional non-muscle myosin, and mutations in MYH10 have been shown to cause neurological defects. PAQR8 has been associated with epilepsy, which exhibits symptoms similar to JEV infection. JE is a neuro-degenerative disease, and the known involvement of MYH10 and PAQR8 in neurological disorders strongly indicates potential roles of these host factors in JEV infection. Additionally, we observed that MYH10 and PAQR8 had a significant negative correlation with Activating transcription factor 3 (ATF3), which is a previously validated modulator of JEV infection. ATF3 is a transcription factor that binds to the promotors of genes encoding other transcription factors or interferon-stimulated genes and negatively regulates host antiviral responses during JE.

CONCLUSION

Our findings demonstrate the significance of data reanalysis in the identification of novel host factors that may become targets for diagnosis/ therapy against viral diseases of major concern, such as, JE. The deregulated coding and non-coding transcripts identified in this study need further experimental analysis for validation.

Circumventing the packaging limit of AAV-mediated gene replacement therapy for neurological disorders

INTRODUCTION

Gene therapy provides the exciting opportunity of a curative single treatment for devastating diseases, eradicating the need for chronic medication. Adeno-associated viruses (AAVs) are among the most attractive vector carriers for gene replacement in vivo. Yet, despite the success of recent AAV-based clinical trials, the clinical use of these vectors has been limited. For instance, the AAV packaging capacity is restricted to ~4.7 kb, making it a substantial challenge to deliver large gene products.

AREAS COVERED

In this review, we explore established and emerging strategies that circumvent the packaging limit of AAVs to make them effective vehicles for gene replacement therapy of monogenic disorders, with a particular focus on diseases affecting the nervous system. We report historical references, design remarks, as well as strengths and weaknesses of these approaches. We additionally discuss examples of neurological disorders for which such strategies have been attempted.

EXPERT OPINION

The field of AAV-gene therapy has experienced enormous advancements in the last decade. However, there is still ample space for improvement aimed at overcoming existing challenges that are slowing down the progressive trajectory of this field.

Chikungunya Immunopathology as It Presents in Different Organ Systems

Chikungunya virus (CHIKV) is currently an urgent public health problem as high morbidity from the virus leaves populations with negative physical, social, and economic impacts. CHIKV has the potential to affect every organ of an individual, leaving patients with lifelong impairments which negatively affect their quality of life. In this review, we show the importance of CHIKV in research and public health by demonstrating the immunopathology of CHIKV as it presents in different organ systems. Papers used in this review were found on PubMed, using “chikungunya and [relevant organ system]”. There is a significant inflammatory response during CHIKV infection which affects several organ systems, such as the brain, heart, lungs, kidneys, skin, and joints, and the immune response to CHIKV in each organ system is unique. Whilst there is clinical evidence to suggest that serious complications can occur, there is ultimately a lack of understanding of how CHIKV can affect different organ systems. It is important for clinicians to understand the risks to their patients.

Improved gliotransmission by increasing intracellular Ca2+ via TRPV1 on multi-walled carbon nanotube platforms

Background

Astrocyte is a key regulator of neuronal activity and excitatory/inhibitory balance via gliotransmission. Recently, gliotransmission has been identified as a novel target for neurological diseases. However, using the properties of nanomaterials to modulate gliotransmission has not been uncovered.

Results

We prepared non-invasive CNT platforms for cells with different nanotopography and properties such as hydrophilicity and conductivity. Using CNT platforms, we investigated the effect of CNT on astrocyte functions participating in synaptic transmission by releasing gliotransmitters. Astrocytes on CNT platforms showed improved cell adhesion and proliferation with upregulated integrin and GFAP expression. In addition, intracellular GABA and glutamate in astrocytes were augmented on CNT platforms. We also demonstrated that gliotransmitters in brain slices were increased by ex vivo incubation with CNT. Additionally, intracellular resting Ca²⁺ level, which is important for gliotransmission, was also increased via TRPV1 on CNT platforms.

Conclusion

CNT can improve astrocyte function including adhesion, proliferation and gliotransmission by increasing resting Ca²⁺ level. Therefore, our study suggests that CNT would be utilized as a new therapeutic platform for central nervous system diseases by modulating gliotransmission.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01551-1.

Effect of Chitosan on Alginate-Based Macroporous Hydrogels for the Capture of Glioblastoma Cancer Cells

Glioblastoma multiforme is a type of brain cancer associated with a very low survival rate since a large number of cancer cells remain infiltrated in the brain despite the treatments currently available. This work presents a macroporous hydrogel trap, destined to be implanted in the surgical cavity following tumor resection and designed to attract and retain cancer cells, in order to eliminate them afterward with a lethal dose of stereotactic radiotherapy. The biocompatible hydrogel formulation comprises sodium alginate (SA) and chitosan (CHI) bearing complementary electrostatic charges and stabilizing the gels in saline and cell culture media, as compared to pristine SA gels. The highly controlled and interconnected porosity, characterized by X-ray microCT, yields mechanical properties comparable to those of brain tissues and allows F98 glioblastoma cells to penetrate the gels within the entire volume, as confirmed by fluorescence microscopy. The addition of a grafted -RGD peptide on SA, combined with CHI, significantly enhances the adhesion and retention of F98 cells within the gels. Overall, the best compromise between low proliferation and a high level of accumulation and retention of F98 cells was obtained with the hydrogel formulated with 1% SA and 0.2% CHI, without the -RGD adhesion peptide.

Study of Calcium Signaling in Astrocytes with a Novel Endoplasmic Reticulum-Targeted GCaMP Sensor

The endoplasmic reticulum (ER), the major organelle for the storage of Ca²⁺ , maintains a concentration of Ca²⁺ much higher than in the cytosol or other subcellular organelles, such as the mitochondria. A variety of tools have been developed for measuring Ca²⁺ activity in neuronal and glial cells, but most of these sensors target either the plasma membrane (PM) or the cytosol. Though these sensors are important for measuring Ca²⁺ transients, they lack the capability to measure activity in the periphery of the ER or to measure low-amplitude events resulting from Ca²⁺ exchange between the ER and other organelles, such as the mitochondria. We recently developed an ER-targeted GCaMP6f anchored to the cytosolic side of the ER that can measure minute calcium exchange occurring in this region. In this article, we discuss detailed methods to characterize the ER-GCaMP6f sensor, utilize it for calcium imaging in cultured astrocytes, and assess its expression and calcium imaging in astrocytes in rodent brains. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Expression and characterization of ER-GCaMP6f Support Protocol 1: ER-GCaMP6f-expressing stable cell line generation Basic Protocol 2: In vitro calcium imaging with ER-GCaMP6f Support Protocol 2: Imaging of drug-induced calcium activity Alternate Protocol 1: Transduction of astrocytes with ER-GCaMP6f AAV Alternate Protocol 2: Calcium imaging of astrocytes with Fluo-4 AM Basic Protocol 3: In vivo ER-GCaMP6f expression and slice calcium imaging Support Protocol 3: Pharmacological studies with 2-APB in brain slices.

The Big Picture of Neurodegeneration: A Meta Study to Extract the Essential Evidence on Neurodegenerative Diseases in a Network-Based Approach

The common features of all neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis (ALS), and Huntington's disease, are the accumulation of aggregated and misfolded proteins and the progressive loss of neurons, leading to cognitive decline and locomotive dysfunction. Still, they differ in their ultimate manifestation, the affected brain region, and the kind of proteinopathy. In the last decades, a vast number of processes have been described as associated with neurodegenerative diseases, making it increasingly harder to keep an overview of the big picture forming from all those data. In this meta-study, we analyzed genomic, transcriptomic, proteomic, and epigenomic data of the aforementioned diseases using the data of 234 studies in a network-based approach to study significant general coherences but also specific processes in individual diseases or omics levels. In the analysis part, we focus on only some of the emerging findings, but trust that the meta-study provided here will be a valuable resource for various other researchers focusing on specific processes or genes contributing to the development of neurodegeneration.

Investigation of Cytotoxicity and Oxidative Stress Induced by the Pyrethroid Bioallethrin in Human Glioblastoma Cells: The Protective Effect of Vitamin E (VE) and Its Underlying Mechanism

Bioallethrin belongs to the family of pyrethroid insecticides. Previous studies have shown that bioallethrin affected the function of muscarinic receptor and subsequently induced neurotoxicity in different brain models. Reactive oxygen species (ROS) are generated in the metabolic course of the human body, which can cause human damage when overactivated. However, whether bioallethrin evokes cytotoxicity through ROS signaling and whether the antioxidant Vitamin E (VE) protects these cytotoxic responses in human glial cell model are still elusive. This study investigated the effect of bioallethrin on cytotoxicity through ROS signaling and evaluated the protective effect of the antioxidant VE in DBTRG-05MG human glioblastoma cells. The cell counting kit-8 (CCK-8) was used to measure cell viability. Intracellular ROS and glutathione (GSH) levels were measured by a cellular assay kit. The levels of apoptosis- and antioxidant-related protein were analyzed by Western blotting. In DBTRG-05MG cells, bioallethrin (25-75 μM) concentration-dependently induced cytotoxicity by increasing ROS productions, decreasing GSH contents, and regulating protein expressions related to apoptosis or antioxidation. Furthermore, these cytotoxic effects were partially reversed by VE (20 μM) pretreatment. Together, VE partially lessened bioallethrin-induced apoptosis through oxidative stress in DBTRG-05MG cells. The data assist us in identifying the toxicological mechanism of bioallethrin and offer future development of the antioxidant VE to reduce brain damage caused by bioallethrin.

Dihydromyricetin improves social isolation-induced cognitive impairments and astrocytic changes in mice

Social isolation induces stress, anxiety, and mild cognitive impairment that could progress towards irreversible brain damage. A probable player in the mechanism of social isolation-induced anxiety is astrocytes, specialized glial cells that support proper brain function. Using a social isolation mouse model, we observed worsened cognitive and memory abilities with reductions of Object Recognition Index (ORI) in novel object recognition test and Recognition Index (RI) in novel context recognition test. Social isolation also increased astrocyte density, reduced astrocyte size with shorter branches, and reduced morphological complexity in the hippocampus. Dihydromyricetin, a flavonoid that we previously demonstrated to have anxiolytic properties, improved memory/cognition and restored astrocyte plasticity in these mice. Our study indicates astrocytic involvement in social isolation-induced cognitive impairment as well as anxiety and suggest dihydromyricetin as an early-stage intervention against anxiety, cognitive impairment, and potential permanent brain damage.

Glucagon-like peptide-1 analogs mitigate neuroinflammation in Alzheimer's disease by suppressing NLRP2 activation in astrocytes

Neuroinflammation is closely linked to the pathogenesis of Alzheimer's disease (AD). Glucagon-like peptide-1 (GLP-1) analogs exhibit anti-inflammatory and neuroprotective effects; hence, we investigated whether they reduce cognitive impairment and protect astrocytes from oxidative stress. We found that 5 × FAD transgenic mice treated with the synthetic GLP-1 receptor agonist exenatide had improved cognitive function per the Morris water maze test. Immunohistochemistry, western blotting, and ELISAs used to detect inflammatory factors revealed reduced neuroinflammation in extracted piriform cortexes of exenatide-treated mice as well as lower amyloid β_1-42-induced oxidative stress and inflammation in astrocytes treated with exendin-4 (the natural analog of exenatide). Adenovirus-mediated overexpression of nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 2 (NLRP2) revealed that exenatide/exendin-4 function may be attributed to NLRP2 inflammasome inhibition. Collectively, our results indicate that GLP-1 analogs improve cognitive dysfunction in vivo and protect astrocytes in vitro, potentially via the downregulation of the NLRP2 inflammasome.

Involvement of FoxO1, Sp1, and Nrf2 in Upregulation of Negative Regulator of ROS by 15d-PGJ2 Attenuates H2O2-Induced IL-6 Expression in Rat Brain Astrocytes

Excessive production of reactive oxygen species (ROS) by NADPH oxidase (Nox) resulted in inflammation. The negative regulator of ROS (NRROS) dampens ROS generation during inflammatory responses. 15-Deoxy-∆12,14-prostaglandin J₂ (15d-PGJ₂) exhibits neuroprotective effects on central nervous system (CNS). However, whether 15d-PGJ₂-induced NRROS expression was unknown in rat brain astrocytes (RBA-1). NRROS expression was determined by Western blot, RT/real-time PCR, and promoter activity assays. The signaling components were investigated using pharmacological inhibitors or specific siRNAs. The interaction between transcription factors and the NRROS promoter was investigated by chromatin immunoprecipitation assay. Upregulation of NRROS on the hydrogen peroxide (H₂O₂)-mediated ROS generation and interleukin 6 (IL-6) secretion was measured. 15d-PGJ₂-induced NRROS expression was mediated through PI3K/Akt-dependent activation of Sp1 and FoxO1 and established the essential promoter regions. We demonstrated that 15d-PGJ₂ activated PI3K/Akt and following by cooperation between phosphorylated nuclear FoxO1 and Sp1 to initiate the NRROS transcription. In addition, Nrf2 played a key role in NRROS expression induced by 15d-PGJ₂ which was mediated through its phosphorylation. Finally, the NRROS stable clones attenuated the H₂O₂-induced ROS generation and expression of IL-6 through suppressing the Nox-2 activity. These results suggested that 15d-PGJ₂-induced NRROS expression is mediated through a PI3K/Akt-dependent FoxO1 and Sp1 phosphorylation, and Nrf2 cascade, which suppresses ROS generation through attenuating the p47^phox phosphorylation and gp91^phox formation and IL-6 expression in RBA-1 cells. These results confirmed the mechanisms underlying 15d-PGJ₂-induced NRROS expression which might be a potential strategy for prevention and management of brain inflammatory and neurodegenerative diseases.

Extracellular Vesicles, Stem Cells and the Role of miRNAs in Neurodegeneration

There are different modalities of intercellular communication governed by cellular homeostasis. In this review, we will explore one of these forms of communication called extracellular vesicles (EVs). These vesicles are released by all cells in the body and are heterogeneous in nature. The primary function of EVs is to share information through their cargo consisting of proteins, lipids and nucleic acids (mRNA, miRNA, dsDNA etc.) with other cells, which have a direct consequence on their microenvironment. We will focus on the role of EVs of mesenchymal stem cells (MSCs) in the nervous system and how these participate in intercellular communication to maintain physiological function and provide neuroprotection. However, deregulation of this same communication system could play a role in several neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Amyotrophic lateral sclerosis, multiple sclerosis, prion disease and Huntington's disease. The release of EVs from a cell provides crucial information to what is happening inside the cell and thus could be used in diagnostics and therapy. We will discuss and explore new avenues for the clinical applications of using engineered MSC-EVs and their potential therapeutic benefit in treating neurodegenerative diseases.

Polychlorinated biphenyls induce oxidative stress and metabolic responses in astrocytes

Exposure to environmental toxicants is prevalent, hazardous and linked to varied detrimental health outcomes and disease. Polychlorinated biphenyls (PCBs), a class of hazardous organic chlorines once widely used for industrial purposes, are associated with neurodegenerative disease and oxidative stress in both in vitro and in vivo models. Here, we investigated the impact of Aroclor 1254, a commercially available PCB mixture, on primary murine astrocytes to determine the response to this once ubiquitously used toxicant on the most numerous cells of the central nervous system (CNS). Astrocytes are a critical component of homeostasis throughout the CNS, including at the blood-brain barrier, where they serve as the primary defense against xenobiotics entering the CNS, and at the synapse, where they are closely coupled to neurons through several metabolic pathways. We hypothesized that PCBs cause astrocytic oxidative stress and related dysfunction including altered metabolism. We exposed primary murine cortical astrocytes to PCBs and report an increased expression of antioxidant genes (Prdx1, Gsta2, Gfap, Amigo2) in response to oxidative stress. Our data show increased ATP production and spare respiratory capacity in astrocytes exposed to 10 μM (∼ 3 ppm) PCBs. This dose also causes an increase in glucose uptake that is not seen at a higher dose (50 μM) suggesting that, at a lower dose, astrocytes are able to engage compensatory mechanisms to promote survival. Together, these data suggest that exposure to PCBs impact astrocytic metabolism, which is important to consider both in the context of human health and disease and in in vitro and in vivo disease models.

Proteomic profiling dataset of chemical perturbations in multiple biological backgrounds

While gene expression profiling has traditionally been the method of choice for large-scale perturbational profiling studies, proteomics has emerged as an effective tool in this context for directly monitoring cellular responses to perturbations. We previously reported a pilot library containing 3400 profiles of multiple perturbations across diverse cellular backgrounds in the reduced-representation phosphoproteome (P100) and chromatin space (Global Chromatin Profiling, GCP). Here, we expand our original dataset to include profiles from a new set of cardiotoxic compounds and from astrocytes, an additional neural cell model, totaling 5300 proteomic signatures. We describe filtering criteria and quality control metrics used to assess and validate the technical quality and reproducibility of our data. To demonstrate the power of the library, we present two case studies where data is queried using the concept of "connectivity" to obtain biological insight. All data presented in this study have been deposited to the ProteomeXchange Consortium with identifiers PXD017458 (P100) and PXD017459 (GCP) and can be queried at https://clue.io/proteomics .

Utilising Induced Pluripotent Stem Cells in Neurodegenerative Disease Research: Focus on Glia

Induced pluripotent stem cells (iPSCs) are a self-renewable pool of cells derived from an organism's somatic cells. These can then be programmed to other cell types, including neurons. Use of iPSCs in research has been two-fold as they have been used for human disease modelling as well as for the possibility to generate new therapies. Particularly in complex human diseases, such as neurodegenerative diseases, iPSCs can give advantages over traditional animal models in that they more accurately represent the human genome. Additionally, patient-derived cells can be modified using gene editing technology and further transplanted to the brain. Glial cells have recently become important avenues of research in the field of neurodegenerative diseases, for example, in Alzheimer's disease and Parkinson's disease. This review focuses on using glial cells (astrocytes, microglia, and oligodendrocytes) derived from human iPSCs in order to give a better understanding of how these cells contribute to neurodegenerative disease pathology. Using glia iPSCs in in vitro cell culture, cerebral organoids, and intracranial transplantation may give us future insight into both more accurate models and disease-modifying therapies.

Permeability of the Blood-Brain Barrier after Traumatic Brain Injury; Radiological Considerations

Traumatic brain injury (TBI) is a leading cause of death and disability, especially in young persons, and constitutes a major socioeconomic burden worldwide. It is regarded as the leading cause of mortality and morbidity in previously healthy young persons. Most of the mechanisms underpinning the development of secondary brain injury are consequences of disruption of the complex relationship between the cells and proteins constituting the neurovascular unit or a direct result of loss of integrity of the tight junctions (TJ) in the blood-brain barrier (BBB). A number of changes have been described in the BBB after TBI, including loss of TJ proteins, pericyte loss and migration, and altered expressions of water channel proteins at astrocyte end-feet processes. There is a growing research interest in identifying optimal biological and radiological biomarkers of severity of BBB dysfunction and its effects on outcomes after TBI. This review explores the microscopic changes occurring at the neurovascular unit, after TBI, and current radiological adjuncts for its evaluation in pre-clinical and clinical practice.

Potential Roles of the WNT Signaling Pathway in Amyotrophic Lateral Sclerosis

The WNT signaling pathway plays an important role in the physiological and pathophysiological processes of the central nervous system and the neurodegenerative disease amyotrophic lateral sclerosis (ALS). We reviewed the literature pertinent to WNT/β–catenin signaling in ALS from cellular studies, animal models, and human clinical trials. WNT, WNT receptors, and other components of the WNT signaling pathway are expressed in both ALS patients and transgenic mice, and are involved in the pathogenesis of ALS. Studies have shown that abnormal activation of the WNT/β–catenin signaling pathway is related to neuronal degeneration and glial cell proliferation. WNT/Ca²⁺ signaling is associated with the pro–inflammatory phenotype of microglia; data on the muscle skeletal receptor Tyr kinase receptor in superoxide dismutase–1–G93A mice indicate that gene therapy is necessary for successful treatment of ALS. The varying profiles of lipoprotein receptor–related protein 4 antibodies in different ethnic groups suggest that individual treatment and multifactorial personalized approaches may be necessary for effective ALS therapy. In conclusion, the WNT signaling pathway is important to the ALS disease process, making it a likely therapeutic target.

A State of the Art of Antioxidant Properties of Curcuminoids in Neurodegenerative Diseases

Neurodegenerative diseases represent a set of pathologies characterized by an irreversible and progressive, and a loss of neuronal cells in specific areas of the brain. Oxidative phosphorylation is a source of energy production by which many cells, such as the neuronal cells, meet their energy needs. Dysregulations of oxidative phosphorylation induce oxidative stress, which plays a key role in the onset of neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). To date, for most neurodegenerative diseases, there are no resolute treatments, but only interventions capable of alleviating the symptoms or slowing the course of the disease. Therefore, effective neuroprotection strategies are needed. In recent years, natural products, such as curcuminoids, have been intensively explored and studied for their therapeutic potentials in several neurodegenerative diseases. Curcuminoids are, nutraceutical compouns, that owen several therapeutic properties such as anti-oxidant, anti-inflammatory and neuroprotective effects. In this context, the aim of this review was to provide an overview of preclinical and clinical evidence aimed to illustrate the antioxidant effects of curcuminoids in neurodegenerative diseases. Promising results from preclinical studies encourage the use of curcuminoids for neurodegeneration prevention and treatment.

Degenerative Cervical Myelopathy: Insights into Its Pathobiology and Molecular Mechanisms

Degenerative cervical myelopathy (DCM), earlier referred to as cervical spondylotic myelopathy (CSM), is the most common and serious neurological disorder in the elderly population caused by chronic progressive compression or irritation of the spinal cord in the neck. The clinical features of DCM include localised neck pain and functional impairment of motor function in the arms, fingers and hands. If left untreated, this can lead to significant and permanent nerve damage including paralysis and death. Despite recent advancements in understanding the DCM pathology, prognosis remains poor and little is known about the molecular mechanisms underlying its pathogenesis. Moreover, there is scant evidence for the best treatment suitable for DCM patients. Decompressive surgery remains the most effective long-term treatment for this pathology, although the decision of when to perform such a procedure remains challenging. Given the fact that the aged population in the world is continuously increasing, DCM is posing a formidable challenge that needs urgent attention. Here, in this comprehensive review, we discuss the current knowledge of DCM pathology, including epidemiology, diagnosis, natural history, pathophysiology, risk factors, molecular features and treatment options. In addition to describing different scoring and classification systems used by clinicians in diagnosing DCM, we also highlight how advanced imaging techniques are being used to study the disease process. Last but not the least, we discuss several molecular underpinnings of DCM aetiology, including the cells involved and the pathways and molecules that are hallmarks of this disease.

RNA Localization and Local Translation in Glia in Neurological and Neurodegenerative Diseases: Lessons from Neurons

Cell polarity is crucial for almost every cell in our body to establish distinct structural and functional domains. Polarized cells have an asymmetrical morphology and therefore their proteins need to be asymmetrically distributed to support their function. Subcellular protein distribution is typically achieved by localization peptides within the protein sequence. However, protein delivery to distinct cellular compartments can rely, not only on the transport of the protein itself but also on the transport of the mRNA that is then translated at target sites. This phenomenon is known as local protein synthesis. Local protein synthesis relies on the transport of mRNAs to subcellular domains and their translation to proteins at target sites by the also localized translation machinery. Neurons and glia specially depend upon the accurate subcellular distribution of their proteome to fulfil their polarized functions. In this sense, local protein synthesis has revealed itself as a crucial mechanism that regulates proper protein homeostasis in subcellular compartments. Thus, deregulation of mRNA transport and/or of localized translation can lead to neurological and neurodegenerative diseases. Local translation has been more extensively studied in neurons than in glia. In this review article, we will summarize the state-of-the art research on local protein synthesis in neuronal function and dysfunction, and we will discuss the possibility that local translation in glia and deregulation thereof contributes to neurological and neurodegenerative diseases.

The Association between Hepatic Encephalopathy and Diabetic Encephalopathy: The Brain-Liver Axis

Hepatic encephalopathy (HE) is one of the main consequences of liver disease and is observed in severe liver failure and cirrhosis. Recent studies have provided significant evidence that HE shows several neurological symptoms including depressive mood, cognitive dysfunction, impaired circadian rhythm, and attention deficits as well as motor disturbance. Liver disease is also a risk factor for the development of diabetes mellitus. Diabetic encephalopathy (DE) is characterized by cognitive dysfunction and motor impairment. Recent research investigated the relationship between metabolic changes and the pathogenesis of neurological disease, indicating the importance between metabolic organs and the brain. Given that a diverse number of metabolites and changes in the brain contribute to neurologic dysfunction, HE and DE are emerging types of neurologic disease. Here, we review significant evidence of the association between HE and DE, and summarise the common risk factors. This review may provide promising therapeutic information and help to design a future metabolic organ-related study in relation to HE and DE.

Motoneuron deafferentation and gliosis occur in association with neuromuscular regressive changes during ageing in mice

BACKGROUND

The cellular mechanisms underlying the age-associated loss of muscle mass and function (sarcopenia) are poorly understood, hampering the development of effective treatment strategies. Here, we performed a detailed characterization of age-related pathophysiological changes in the mouse neuromuscular system.

METHODS

Young, adult, middle-aged, and old (1, 4, 14, and 24-30 months old, respectively) C57BL/6J mice were used. Motor behavioural and electrophysiological tests and histological and immunocytochemical procedures were carried out to simultaneously analyse structural, molecular, and functional age-related changes in distinct cellular components of the neuromuscular system.

RESULTS

Ageing was not accompanied by a significant loss of spinal motoneurons (MNs), although a proportion (~15%) of them in old mice exhibited an abnormally dark appearance. Dark MNs were also observed in adult (~9%) and young (~4%) animals, suggesting that during ageing, some MNs undergo early deleterious changes, which may not lead to MN death. Old MNs were depleted of cholinergic and glutamatergic inputs (~40% and ~45%, respectively, P < 0.01), suggestive of age-associated alterations in MN excitability. Prominent microgliosis and astrogliosis [~93% (P < 0.001) and ~100% (P < 0.0001) increase vs. adults, respectively] were found in old spinal cords, with increased density of pro-inflammatory M1 microglia and A1 astroglia (25-fold and 4-fold increase, respectively, P < 0.0001). Ageing resulted in significant reductions in the nerve conduction velocity and the compound muscle action potential amplitude (~30%, P < 0.05, vs. adults) in old distal plantar muscles. Compared with adult muscles, old muscles exhibited significantly higher numbers of both denervated and polyinnervated neuromuscular junctions, changes in fibre type composition, higher proportion of fibres showing central nuclei and lipofuscin aggregates, depletion of satellite cells, and augmented expression of different molecules related to development, plasticity, and maintenance of neuromuscular junctions, including calcitonin gene-related peptide, growth associated protein 43, agrin, fibroblast growth factor binding protein 1, and transforming growth factor-β1. Overall, these alterations occurred at varying degrees in all the muscles analysed, with no correlation between the age-related changes observed and myofiber type composition or muscle topography.

CONCLUSIONS

Our data provide a global view of age-associated neuromuscular changes in a mouse model of ageing and help to advance understanding of contributing pathways leading to development of sarcopenia.

Brain injury and repair after intracerebral hemorrhage: The role of microglia and brain-infiltrating macrophages

Intracerebral hemorrhage (ICH) is a major public health problem characterized by cerebral bleeding. Despite recent advances in preclinical studies, there is no effective treatment for ICH making it the deadliest subtype of stroke. The lack of effective treatment options partly attributes to the complexity as well as poorly defined pathophysiology of ICH. The emerging evidence indicates the potential of targeting secondary brain damage and hematoma resolution for improving neurological outcomes after ICH. Herein, we provide an overview of our understanding of the functional roles of activated microglia and brain-infiltrating monocyte-derived macrophages in brain injury and repair after ICH. The clinical and preclinical aspects that we discuss in this manuscript are related to ICH that occurs in adults, but not in infants. Also, we attempt to identify the knowledge gap in the field for future functional studies given the potential of targeting microglia and brain-infiltrating macrophages for therapeutic intervention after ICH.

Rapid induction of gliogenesis in OLIG2 and NKX2.2-expressing progenitors-derived spheroids

Glial cells are crucial for the development of the central nervous system and the maintenance of chemical homeostasis. The process of gliogenesis has been well studied in the rodent brain, but it remains less well studied in the human brain. In addition, rodent glial cells differ from human counterparts in terms of morphologies, functions, and anatomical locations. Cerebral organoids (also referred to as spheroids) derived from human pluripotent stem cells (hPSCs) have been developed and are suitable cell-based models for researching developmental and neurodegenerative diseases. The in vitro generation of glia, including astrocytes and oligodendrocytes, from such organoids represents a promising tool to model neuronal diseases. Here, we showed that three-dimensional (3D) culture of OLIG2- and NKX2.2-expressing neurospheres produced efficiently mature astrocytes and oligodendrocytes in terms of morphologies and expression pattern recapitulating native 3D environment. Our findings provide important insights for developmental research of the human brain and glial specification that may facilitate patient-specific disease modeling.

Oligodendrocyte pathology exceeds axonal pathology in white matter in human amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease. The majority of cases are sporadic (sALS), while the most common inherited form is due to C9orf72 mutation (C9ALS). A high burden of inclusion pathology is seen in glia (including oligodendrocytes) in ALS, especially in C9ALS. Myelin basic protein (MBP) messenger RNA (mRNA) must be transported to oligodendrocyte processes for myelination, a possible vulnerability for normal function. TDP43 is found in pathological inclusions in ALS and is a component of mRNA transport granules. Thus, TDP43 aggregation could lead to MBP loss. Additionally, the hexanucleotide expansion of mutant C9ALS binds hnRNPA2/B1, a protein essential for mRNA transport, causing potential further impairment of hnRNPA2/B1 function, and thus myelination. Using immunohistochemistry for p62 and TDP43 in human post-mortem tissue, we found a high burden of glial inclusions in the prefrontal cortex, precentral gyrus, and spinal cord in ALS, which was greater in C9ALS than in sALS cases. Double staining demonstrated that the majority of these inclusions were in oligodendrocytes. Using immunoblotting, we demonstrated reduced MBP protein levels relative to PLP (a myelin component that relies on protein not mRNA transport) and neurofilament protein (an axonal marker) in the spinal cord. This MBP loss was disproportionate to the level of PLP and axonal loss, suggesting that impaired mRNA transport may be partly responsible. Finally, we show that in C9ALS cases, the level of oligodendroglial inclusions correlates inversely with levels of hnRNPA2/B1 and the number of oligodendrocyte precursor cells. We conclude that there is considerable oligodendrocyte pathology in ALS, which at least partially reflects impairment of mRNA transport. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Bim expression modulates the pro-inflammatory phenotype of retinal astroglial cells

Apoptosis of neurovascular cells, including astroglial cells, contributes to the pathogenesis of diseases in which neurovascular disruption plays a central role. Bim is a pro-apoptotic protein that modulates not only apoptosis but also various cellular functions such as migration and extracellular matrix protein expression. Astroglial cells act as an intermediary between neural and vascular cells facilitating retinal vascular development and remodeling while maintaining normal vascular function and neuronal integrity. We previously showed that Bim deficient (Bim -/-) mice were protected from hyperoxia mediated vessel obliteration and ischemia-mediated retinal neovascularization. However, the underlying mechanisms and more specifically the role Bim expression in astroglial cells play remains elusive. Here, using retinal astroglial cells prepared from wild-type and Bim -/- mice, we determined the impact of Bim expression in retinal astroglial cell function. We showed that astroglial cells lacking Bim expression demonstrate increased VEGF expression and altered matricellular protein production including increased expression of thrombospondin-2 (TSP2), osteopontin and SPARC. Bim deficient astroglial cells also exhibited altered proliferation, migration, adhesion to various extracellular matrix proteins and increased expression of inflammatory mediators. Thus, our data emphasizes the importance of Bim expression in retinal astroglia cell autonomous regulatory mechanisms, which could influence neurovascular function.

Cell Type-Specific Gene Network-Based Analysis Depicts the Heterogeneity of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a complex neuropsychiatric disorder characterized by substantial heterogeneity. To identify the convergence of disease pathology on common pathways, it is essential to understand the correlations among ASD candidate genes and study shared molecular pathways between them. Investigating functional interactions between ASD candidate genes in different cell types of normal human brains may shed new light on the genetic heterogeneity of ASD. Here we apply cell type-specific gene network-based analysis to analyze human brain nucleus gene expression data and identify cell type-specific ASD-associated gene modules. ASD-associated modules specific to different cell types are relevant to different gene functions, for instance, the astrocytes-specific module is involved in functions of axon and neuron projection guidance, GABAergic interneuron-specific modules are involved in functions of postsynaptic membrane, extracellular matrix structural constituent, and ion transmembrane transporter activity. Our findings can promote the study of cell type heterogeneity of ASD, providing new insights into the pathogenesis of ASD. Our method has been shown to be effective in discovering cell type-specific disease-associated gene expression patterns and can be applied to other complex diseases.

The journey of Zika to the developing brain

Zika virus is a mosquito-borne Flavivirus originally isolated from humans in 1952. Following its re-emergence in Brazil in 2015, an increase in the number of babies born with microcephaly to infected mothers was observed. Microcephaly is a neurodevelopmental disorder, characterised phenotypically by a smaller than average head size, and is usually developed in utero. The 2015 outbreak in the Americas led to the World Health Organisation declaring Zika a Public Health Emergency of International Concern. Since then, much research into the effects of Zika has been carried out. Studies have investigated the structure of the virus, its effects on and evasion of the immune response, cellular entry including target receptors, its transmission from infected mother to foetus and its cellular targets. This review discusses current knowledge and novel research into these areas, in hope of developing a further understanding of how exposure of pregnant women to the Zika virus can lead to impaired brain development of their foetus. Although no longer considered an epidemic in the Americas, the mechanism by which Zika acts is still not comprehensively and wholly understood, and this understanding will be crucial in developing effective vaccines and treatments.

Extracellular Mitochondrial Dysfunction in Cerebrospinal Fluid of Patients with Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Mitochondrial dysfunction is related to brain ischemic injury and neural cell death. However, little is known about the association between mitochondrial dysfunction of cerebrospinal fluid (CSF) and delayed cerebral ischemia (DCI) following subarachnoid hemorrhage (SAH). The objective of this study was to investigate whether extracellular CSF mitochondria might serve as a potential biomarker for DCI.

METHODS

CSF samples were serially collected at 1, 3, and 5 days following SAH in 33 patients (DCI, n = 12; and non-DCI, n = 21) who underwent coil embolization. To monitor mitochondrial membrane potentials, JC-1 dye was used. The ratio (red/green) of JC-1 was considered as an indicator of intact mitochondrial membrane potential. Flow cytometry was done to analyze extracellular mitochondria particles and their possible cellular origins.

RESULTS

DCI patients had lower JC-1 red/green ratios than non-DCI patients at 1 day (3.35 [3.20-3.75] vs. 3.70 [3.40-3.95] in non-DCI) and 3 days (4.65 [4.45-5.00] vs. 5.10 [4.65-5.30] in non-DCI) after SAH. At 5 days after SAH, JC-1 red/green ratio was significantly lower in DCI than that in non-DCI (3.05 [2.90-3.35] vs. 4.20 [4.10-4.50]; p < 0.01) patients. DCI patients had a higher percentage of vWF-positive mitochondria (40.10% [38.25%-44.90%] vs. 30.20% [25.70%-36.68%]) and a lower percentage of GLAST-positive mitochondria particles (26.85% [17.10%-30.00%] vs. 31.60% [26.70%-35.00%]) than non-DCI patients. However, there was no significant difference in CD45-positive (p = 0.369) or CD41/61-positive mitochondrial particles (p = 0.155) between the two groups of patients.

CONCLUSIONS

Mitochondrial membrane potential could be a marker of DCI. JC-1 ratios seemed to be able to predict future DCI onset. Further studies are needed to determine detailed mechanisms of extracellular mitochondria-mediated cell-to-cell signals in DCI.

The Direct Contribution of Astrocytes and Microglia to the Pathogenesis of Hepatic Encephalopathy

Hepatic encephalopathy is a neurological complication resulting from loss of hepatic function and is associated with poor clinical outcomes. During acute liver failure over 20% of mortality can be associated with the development of hepatic encephalopathy. In patients with liver cirrhosis, 1-year survival for those that develop overt hepatic encephalopathy is under 50%. The pathogenesis of hepatic encephalopathy is complicated due to the multiple disruptions in homeostasis that occur following a reduction in liver function. Of these, elevations of ammonia and neuroinflammation have been shown to play a significant contributing role to the development of hepatic encephalopathy. Disruption of the urea cycle following liver dysfunction leads to elevations of circulating ammonia, which enter the brain and disrupt the functioning of astrocytes. This results in dysregulation of metabolic pathways in astrocytes, oxidative stress and cerebral edema. Besides ammonia, circulating chemokines and cytokines are increased following liver injury, leading to activation of microglia and a subsequent neuroinflammatory response. The combination of astrocyte dysfunction and microglia activation are significant contributing factors to the pathogenesis of hepatic encephalopathy.

The Role of Microglia and Astrocytes in Huntington's Disease

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease. HD patients present with movement disorders, behavioral and psychiatric symptoms and cognitive decline. This review summarizes the contribution of microglia and astrocytes to HD pathophysiology. Neuroinflammation in the HD brain is characterized by a reactive morphology in these glial cells. Microglia and astrocytes are critical in regulating neuronal activity and maintaining an optimal milieu for neuronal function. Previous studies provide evidence that activated microglia and reactive astrocytes contribute to HD pathology through transcriptional activation of pro-inflammatory genes to perpetuate a chronic inflammatory state. Reactive astrocytes also display functional changes in glutamate and ion homeostasis and energy metabolism. Astrocytic and microglial changes may further contribute to the neuronal death observed with the progression of HD. Importantly, the degree to which these neuroinflammatory changes are detrimental to neurons and contribute to the progression of HD pathology is not well understood. Furthermore, recent observations provide compelling evidence that activated microglia and astrocytes exert a variety of beneficial functions that are essential for limiting tissue damage and preserving neuronal function in the HD brain. Therefore, a better understanding of the neuroinflammatory environment in the brain in HD may lead to the development of targeted and innovative therapeutic opportunities.

The neuroprotection of progesterone against Aβ-induced NLRP3-Caspase-1 inflammasome activation via enhancing autophagy in astrocytes

Neuroinflammation and autophagy dysfunction are known to be involved in the pathological procession of Alzheimer's disease (AD). Progesterone (PG), neuroactive steroids, exerts a characteristic neuroprotective function in improving AD syndrome. The NOD-like receptor pyrin 3 (NLRP3)-Caspase-1 inflammasome has specific relevance to AD pathological procession. However, the exact role of PG in regulating NLRP3-Caspase-1 inflammasome remains to be elucidated. We demonstrated Aβ up-regulated IL-1β expression in astrocytes by activating NLRP3-Caspase-1 inflammasome. However, pharmacological activation of autophagy by Rapamycin (RAPA) efficiently suppressed Aβ-, lipopolysaccharides (LPS)-induced IL-1β expression via regulating NLRP3-Caspase-1 inflammasome in astrocytes. Remarkably, PG significantly inhibited Aβ-induced NLRP3-Caspase-1 inflammasome activation. Autophagy inhibitor 3-MA blocked the protective effects of PG in mediating NLRP3 inflammasome and IL-1β processing. Taken together, our observations suggest that autophagy-lysosome pathway is one specific molecular mechanism in regulating Aβ-induced NLRP3-Caspase-1 inflammasome activation in astrocytes, particularly uncover the potential neuroprotection of PG in regulating upstream signaling leading to the sequence events of neuroinflammation. That neuroprotective mechanism of PG in regulating NLRP3-Caspase-1 inflammasome can be a potential therapeutic target for ameliorating the pathological procession of AD.

Could an Impairment in Local Translation of mRNAs in Glia be Contributing to Pathogenesis in ALS?

One of the key pathways implicated in amyotrophic lateral sclerosis (ALS) pathogenesis is abnormal RNA processing. Studies to date have focussed on defects in RNA stability, splicing, and translation, but this review article will focus on the largely overlooked RNA processing mechanism of RNA trafficking, with particular emphasis on the importance of glia. In the central nervous system (CNS), oligodendrocytes can extend processes to myelinate and metabolically support up to 50 axons and astrocytes can extend processes to cover up to 100,000 synapses, all with differing local functional requirements. Furthermore, many of the proteins required in these processes are large, aggregation-prone proteins which would be difficult to transport in their fully translated, terminally-folded state. This, therefore, highlights a critical requirement in these cells for local control of protein translation, which is achieved through specific trafficking of mRNAs to each process and local translation therein. Given that a large number of RNA-binding proteins have been implicated in ALS, and RNA-binding proteins are essential for trafficking mRNAs from the nucleus to glial processes for local translation, RNA misprocessing in glial cells is a likely source of cellular dysfunction in ALS. To date, neurons have been the focus of ALS research, but an intrinsic deficit in glia, namely astrocytes and oligodendrocytes, could have an additive effect on declining neuronal function in ALS. This review article aims to highlight the key evidence that supports the contention that RNA trafficking deficits in astrocytes and oligodendrocytes may contribute to in ALS.