Microglia-Astrocyte Crosstalk: An Intimate Molecular Conversation

Potential roles for microglia in drug addiction: Adolescent neurodevelopment and beyond

Adolescence is a sensitive period for development of addiction-relevant brain circuits, and it is also when people typically start experimenting with drugs. Unfortunately, such substance use may cause lasting impacts on the brain, and might increase vulnerability to later-life addictions. Microglia are the brain's immune cells, but their roles in shaping neural connectivity and synaptic plasticity, especially in developmental sensitive periods like adolescence, may also contribute to addiction-related phenomena. Here, we overview how drugs of abuse impact microglia, and propose that they may play poorly-understood, but important roles in addiction vulnerability and progression.

Montelukast's potential as a neuroprotective agent against acrylamide induced neurotoxicity: In vivo and computational modelling

Tobacco consumption, a leading cause of over 8 million deaths annually, exposes individuals to acrylamide (ACY), a neurotoxin in cigarette smoke that disrupts neurotransmitter function and induces oxidative stress, contributing to neurodegeneration. This study evaluated neuroprotective potential of montelukast (MTLU), a leukotriene receptor antagonist with anti-inflammatory and antioxidant properties, against ACY-induced neurotoxicity. Cognitive performance was assessed using elevated plus maze, novel object recognition, and Y-maze tests over 14 days. Biomarkers associated with neurodegeneration (BACE1, GSK-3β, AChE), neuroinflammation (COX-2, PGE2, TNF-α, NF-κB), oxidative stress (GSH, MDA, CAT), and apoptosis (Bcl-2, Caspase-3, Bax) were analyzed. Histopathological analyses of brain tissues were conducted to examine structural damage, and computational studies provided additional support for selected in vivo findings. MTLU significantly ameliorated ACY-induced cognitive deficits and reduced levels of GSK-3β, AChE, COX-2, PGE2, TNF-α, NF-κB, MDA, Bax, and Caspase-3 while enhancing antioxidant defenses (GSH) and upregulating Bcl-2. Histopathological analysis confirmed reduced structural brain damage, and molecular docking indicated strong binding potential for MTLU with AChE, COX-2, GSK-3β, BACE-1, and Caspase-3. While these findings suggest a protective role for MTLU in mitigating ACY-induced cognitive impairments, oxidative stress, neuroinflammation, and apoptosis, further research is needed to confirm its therapeutic potential and clinical relevance.

Spinal astrocyte-derived M-CSF mediates microglial reaction and drives visceral hypersensitivity following DSS-induced colitis

Visceral hypersensitivity is one of the most prevalent symptoms of inflammatory bowel disease (IBD), and it can be difficult to cure despite achieving endoscopic remission. Accumulating studies have described that macrophage colony-stimulating factor (M-CSF) modulates neuroinflammation in the central nervous system (CNS) and the development of chronic pain, while the underlying mechanism for whether and how M-CSF/CSF1R signaling pathway regulates visceral hypersensitivity following colitis remains unknown. In the present study, using the dextran sulfate sodium (DSS)-induced colitis model, we determined that microglial accumulation occurred in the spinal dorsal horn during remission phase. The reactive microglia released inflammatory factor, increased neuronal excitability in the dorsal horn, and produced chronic visceral pain behaviors in DSS-treated adult male mice. In addition, we also found significantly increased signaling mediated by astrocytic M-CSF and microglial CSF1R in dorsal horn in the mice with colitis. Exogenous M-CSF induced microglial activation, neuronal hyperactivity and behavioral hypersensitivity in the control group, inhibition of astrocyte/microglia by fluorocitrate/minocycline significantly suppressed microglial and neuronal activity, and relieved the visceral hypersensitivity in the model mice. Overall, our experimental study uncovers the critical involvement of spinal astrocyte-derived M-CSF and reactive microglia in the initiation and maintenance of visceral hypersensitivity following colitis, thereby identifying spinal M-CSF as a target for treating chronic visceral pain. This may provide more accurate theoretical guidance for clinical patients with IBD.

Tissue-specific decellularized extracellular matrix rich in collagen, glycoproteins, and proteoglycans and its applications in advanced organoid engineering: A review

Decellularized extracellular matrix derived from specific organs represents a promising platform for organoid development, offering distinct advantages in tissue engineering. This matrix maintains the complex three-dimensional network of biological macromolecules secreted by tissue-specific cells, including collagen, glycoproteins, and proteoglycans. This extracellular matrix orchestrates cellular behaviors, such as proliferation, migration, and differentiation, while maintaining optimal tissue homeostasis. The organ-specific composition of decellularized extracellular matrix preserves native biological cues, including growth factors and cytokines, as well as mechanical properties, facilitating natural cell-matrix interactions and promoting appropriate stem cell development. These characteristics make organ-derived decellularized extracellular matrix an ideal scaffold for organoid construction. The implementation of decellularized extracellular matrix enhances the physiological relevance of organoid models, which is particularly valuable in drug development, personalized medicine, and the study of complex organ microenvironments. This advancement significantly improves the translational potential of organoid technology for organ transplantation while providing robust research tools. Consequently, decellularized extracellular matrix-based organoid models offer superior platforms for preclinical therapeutic evaluation. This review examines recent progress in decellularized extracellular matrix-based organoid development, beginning with current application strategies and proceeding to an analysis of existing decellularized extracellular matrix-derived organoid models.

Astrocyte regulation of behavioral outputs: the versatile roles of calcium

Behavior arises from coordinated brain-wide neural and glial networks, enabling organisms to perceive, interpret, and respond to stimuli. Astrocytes play an important role in shaping behavioral output, yet the underlying molecular mechanisms are not fully understood. Astrocytes respond to intrinsic and extrinsic cues with calcium (Ca2+) fluctuations, which are highly heterogeneous across spatio-temporal scales, contexts, and brain regions. This heterogeneity allows astrocytes to exert dynamic regulatory effects on neuronal function but has made it challenging to understand the precise mechanisms and pathways linking astrocytic Ca2+ to specific behavioral outcomes, and the functional relevance of these signals remains unclear. Here, we review recent literature uncovering roles for astrocytic Ca2+ signaling in a wide array of behaviors, including cognitive, homeostatic, and affective focusing on its physiological roles, and potential pathological implications. We specifically highlight how different types of astrocytic Ca2+ signals are linked to distinct behavioral outcomes and discuss limitations and unanswered questions that remain to be addressed.

Refining the interactions between microglia and astrocytes in Alzheimer's disease pathology

Microglia and astrocytes are central to the pathogenesis and progression of Alzheimer's Disease (AD), working both independently and collaboratively to regulate key pathological processes such as β-amyloid protein (Aβ) deposition, tau aggregation, neuroinflammation, and synapse loss. These glial cells interact through complex molecular pathways, including IL-3/IL-3Ra and C3/C3aR, which influence disease progression and cognitive decline. Emerging research suggests that modulating these pathways could offer therapeutic benefits. For instance, recombinant IL-3 administration in mice reduced Aβ plaques and improved cognitive functions, while C3aR inhibition alleviated Aβ and tau pathologies, restored synaptic function, and corrected immune dysregulation. However, the effects of these interactions are context-dependent. Acute C3/C3aR activation enhances microglial Aβ clearance, whereas chronic activation impairs it, highlighting the dual roles of glial signaling in AD. Furthermore, C3/C3aR signaling not only impacts Aβ clearance but also modulates tau pathology and synaptic integrity. Given AD's multifactorial nature, understanding the specific pathological environment is crucial when investigating glial cell contributions. The interplay between microglia and astrocytes can be both neuroprotective and neurotoxic, depending on the disease stage and brain region. This complexity underscores the need for targeted therapies that modulate glial cell activity in a context-specific manner. By elucidating the molecular mechanisms underlying microglia-astrocyte interactions, this research advances our understanding of AD and paves the way for novel therapeutic strategies aimed at mitigating neurodegeneration and cognitive decline in AD and related disorders.

The Double-Edged Effect of Connexins and Pannexins of Glial Cells in Central and Peripheral Nervous System After Nerve Injury

Glial cells play pivotal roles in homeostatic regulation and driving reactive pathologic changes after nerve injury. Connexins (Cxs) and pannexins (Panxs) have emerged as seminal proteins implicated in cell-cell communication, exerting a profound impact on the response processes of glial cell activation, proliferation, protein synthesis and secretion, as well as apoptosis following nerve injury. These influences are mediated through various forms, including protein monomers, hemichannel (HC), and gap junction (GJ), mainly by regulating intercellular or intracellular signaling pathways. Multiple Cx and Panx isoforms have been detected in central nervous system (CNS) or peripheral nervous system (PNS). Each isoform exhibits distinct cellular and subcellular localization, and the differential regulation and functional roles of various protein isoforms are observed post-injury. The quantitative and functional alterations of the same protein isoform in different studies remain inconsistent, attributable to factors such as the predominant mode of protein polymerization, the specific injury model, and the injury site. Similarly, the same protein isoforms have different roles in regulating the response processes after nerve injury, thus exerting a double-edged sword effect. This review describes the regulatory mechanisms and bidirectional effects of Cxs and Panxs. Additionally, it surveys the current status of research and application of drugs as therapeutic targets for neuropathic injuries. We summarize comprehensive and up-to-date information on these proteins in the glial cell response to nerve injury, providing new perspectives for future mechanistic exploration and development of targeted therapeutic approaches.

Mesencephalic astrocyte-derived neurotrophic factor (MANF): A novel therapeutic target for chemotherapy-induced peripheral neuropathy via regulation of integrated stress response and neuroinflammation

Chemotherapy-induced peripheral neuropathy (CIPN) represents a severe complication, impacting up to 90% of cancer patients administered with chemotherapeutic agents such as oxaliplatin. The purpose of our study was to examine the potential role and therapeutic efficacy of Mesencephalic Astrocyte-derived Neurotrophic Factor (MANF), given its recognized neuroprotective and immunomodulatory properties in diverse neurological disorders. Utilizing an oxaliplatin-induced CIPN mouse model, we investigated MANF expression in the dorsal root ganglia (DRG) and spinal cord, and evaluated the impacts of AAV-mediated MANF overexpression on CIPN. Our findings revealed substantial downregulation of MANF expression in both the DRG and spinal cord of CIPN inflicted mice, with MANF majorly localized in neurons as opposed to glial cells. Intrathecal administration of AAV-MANF preceding oxaliplatin treatment yielded several beneficial results. MANF overexpression diminished mechanical hypersensitivity and decreased Calcitonin Gene-Related Peptide (CGRP) expression in DRG and the spinal dorsal horn. These enhancements were concomitant with modulation of the integrated stress response (ISR) and neuroinflammation. Intervention with AAV-MANF effectively regulated ISR markers (BiP, CHOP, and p-eIF2α), mitigated activation of microglia and astrocytes in the DRG and spinal dorsal horn, and inhibited NFκB and ERK inflammatory signaling pathways. To conclude, our study underscores the potential of MANF as a viable therapeutic target for CIPN, manifesting its ability to modulate ISR and neuroinflammation. These insights recommend that continued exploration of MANF-centered approaches could facilitate the advancement of more efficacious interventions for this incapacitating chemotherapy complication.

The Role of Neuroinflammation and Network Anomalies in Drug-Resistant Epilepsy

Epilepsy affects over 50 million people worldwide. Drug-resistant epilepsy (DRE) accounts for up to a third of these cases, and neuro-inflammation is thought to play a role in such cases. Despite being a long-debated issue in the field of DRE, the mechanisms underlying neuroinflammation have yet to be fully elucidated. The pro-inflammatory microenvironment within the brain tissue of people with DRE has been probed using single-cell multimodal transcriptomics. Evidence suggests that inflammatory cells and pro-inflammatory cytokines in the nervous system can lead to extensive biochemical changes, such as connexin hemichannel excitability and disruption of neurotransmitter homeostasis. The presence of inflammation may give rise to neuronal network abnormalities that suppress endogenous antiepileptic systems. We focus on the role of neuroinflammation and brain network anomalies in DRE from multiple perspectives to identify critical points for clinical application. We hope to provide an insightful overview to advance the quest for better DRE treatments.

Nicotine Ameliorates α-Synuclein Preformed Fibril-Induced Behavioral Deficits and Pathological Features in Mice

Epidemiologic study suggests that nicotine reduces the risk of Parkinson's disease (PD) and thus could serve as a potential treatment. In this study, we aimed to investigate the effect of nicotine on the behavioral phenotypes and pathological characteristics of mice induced by human alpha-synuclein preformed fibers (α-syn-PFF). Mice were injected with 5 µg of human α-syn-PFF in the hippocampus while administering nicotine-containing drinking water (200 µg/mL). After 1 month, the motor ability, mood, spatial learning, and memory ability of the PD phenotype-like model mice were detected using open field, rotarod, Y maze, and O maze tests. The expression of pathological α-syn and apoptotic proteins, as well as the number of glial and neural stem cells in the hippocampus of mice, was detected using western blot and immunofluorescence. The results demonstrated that nicotine significantly reduced pathological α-syn accumulation, α-syn serine 129 phosphorylation, and apoptosis induced by α-syn-PFF injection in the hippocampus of mice. Nicotine also inhibited the increase in the number of glia, microglia, and neuronal apoptotic cells, and it decreased the expression of PI3K and Akt while also exhibiting significant memory impairment, motor deficits, and anxiety-like behavior. In conclusion, our findings suggest that nicotine ameliorates behavioral deficits and pathological changes in mice by inhibiting human α-syn-PFF-induced neuroinflammation and apoptosis.

Neuroinflammation and stress-induced pathophysiology in major depressive disorder: mechanisms and therapeutic implications

Major depressive disorder (MDD) is one of the most common mental health conditions, characterized by pervasive and persistent low mood, low self-esteem, and a loss of interest or pleasure in activities that are typically enjoyable. Despite decades of research into the etiology and pathophysiological mechanisms of depression, the therapeutic outcomes for many individuals remain less than expected. A promising new area of research focuses on stress-induced neuroinflammatory processes, such as the excessive activation and crosstalk of microglia and astrocytes in the central nervous system under stress, as well as elevated levels of pro-inflammatory cytokines, which are closely linked to the onset and progression of depression. This review summarizes the mechanisms through which neuroinflammation induces or promotes the development of depression, and also highlights the effective roles of small molecules with anti-inflammatory activity in the treatment of MDD. Understanding the specific mechanisms through which stress-induced neuroinflammation further impacts depression, and using technologies such as single-cell RNA sequencing to elucidate the specific subtypes and interactions of microglia and astrocytes in depression, is of great importance for developing more effective therapeutic strategies for MDD.

Noradrenergic signaling controls Alzheimer's disease pathology via activation of microglial β2 adrenergic receptors

Norepinephrine (NE) is a potent anti-inflammatory agent in the brain. In Alzheimer's disease (AD), the loss of NE signaling heightens neuroinflammation and exacerbates amyloid pathology. NE inhibits surveillance activity of microglia, the brain's resident immune cells, via their β2 adrenergic receptors (β2ARs). Here, we investigate the role of microglial β2AR signaling in AD pathology in the 5xFAD mouse model of AD. We found that loss of cortical NE projections preceded the degeneration of NE-producing neurons and that microglia in 5xFAD mice, especially those microglia that were associated with plaques, significantly downregulated β2AR expression early in amyloid pathology. Importantly, dampening microglial β2AR signaling worsened plaque load and the associated neuritic damage, while stimulating microglial β2AR signaling attenuated amyloid pathology. Our results suggest that microglial β2AR could be explored as a potential therapeutic target to modify AD pathology.

Glial-immune interactions in barrier organs

Neuro-immune interactions within barrier organs, such as lung, gut, and skin, are crucial in regulating tissue homeostasis, inflammatory responses, and host defence. Our rapidly advancing understanding of peripheral neuroimmunology is transforming the field of barrier tissue immunology, offering a fresh perspective for developing therapies for complex chronic inflammatory disorders affecting barrier organs. However, most studies have primarily examined interactions between the peripheral nervous system and the immune system from a neuron-focused perspective, while glial cells, the nonneuronal cells of the nervous system, have received less attention. Glial cells were long considered as mere bystanders, only supporting their neuronal neighbours, but recent discoveries mainly on enteric glial cells in the intestine have implicated these cells in immune-regulation and inflammatory disease pathogenesis. In this review, we will highlight the bi-directional interactions between peripheral glial cells and the immune system and discuss the emerging immune regulatory functions of glial cells in barrier organs.

Early Pro- and Anti-Inflammatory Immune Response Induced by Probiotic Treatment After Th9 Compression: The Interplay Between Spinal Cord and Jejunum

The aim of our study was to limit the inflammatory response after spinal cord injury (SCI) using the probiotic strain Lacticaseibacillus paracasei Ž2 (5 × 109, CFU/mL). The relationship between pro- and anti-inflammatory markers was studied in a rat model after Th9 compression (40 g/15 min) and daily application (7 or 14 days) of probiotics. The probiotic treatment strongly reduced pro-inflammatory markers specific for microglia/macrophages (CD11b), microglia (CD68, IL-6, and iNOS), astrocytes (C1q), and TLR/NF-κB signaling pathway at lesion site and to a lesser extent cranially and caudally (0.3 cm) 7 days postinjury. In the spinal cord segments, 2-week probiotic therapy affected the expression of these targets depending on the intensity of their damage (cranially > caudally > lesion site). It was also noted that the impact of 14-day probiotic therapy in the jejunum was more pronounced than after a shorter treatment. Additionally, probiotic therapy significantly boosted the neuroprotective and anti-inflammatory milieu in the spinal cord tissues. Seven days post-SCI probiotic therapy had the potential to modulate the unfavorable environment around the injury site by increasing the anti-inflammatory microglial (IL-4Rα, TGF-β, and SOCS3) and astroglial (Ptx3) transcripts and by overexpression of immunoregulatory (TLR9 and IFN-γ) markers leading to functional remodeling and mitigation of hematuria. Longer post-SCI probiotic treatment upregulates the neuroprotective molecules at the injury site and simultaneously regulates the anti-inflammatory response in the jejunum. Herein we show that probiotic strain L. paracasei Ž2 has the potential to manage inflammation induced by SCI in both the gut and affected spinal cord within both subacute phases.

Parthenolide regulates microglial and astrocyte function in primary cultures from ALS mice and has neuroprotective effects on primary motor neurons

Over the last twenty years, the role of microgliosis and astrocytosis in the pathophysiology of neurodegenerative diseases has increasingly been recognized. Dysregulation of microglial and astrocyte properties and function has been described also in the fatal degenerative motor neuron disease amyotrophic lateral sclerosis (ALS). Microglia cells, the immune cells of the nervous system, can either have an immunonegative neurotoxic or immunopositive neuroprotective phenotype. The feverfew plant (Tanacetum parthenium) derived compound parthenolide has been found to be capable of interfering with microglial phenotype and properties. Positive treatment effects were shown in animal models of neurodegenerative diseases like Alzheimer's disease and Parkinson's disease. Now we were able to show that PTL has a modulating effect on primary mouse microglia cells, both wild type and SOD1, causing them to adopt a more neuroprotective potential. Furthermore, we were able to show that PTL, through its positive effect on microglia, also has an indirect positive impact on motor neurons, although PTL itself has no direct effect on these primary motor neurons. The results of our study give reason to consider PTL as a drug candidate for ALS.

Lysosomal acidification impairment in astrocyte-mediated neuroinflammation

Astrocytes are a major cell type in the central nervous system (CNS) that play a key role in regulating homeostatic functions, responding to injuries, and maintaining the blood-brain barrier. Astrocytes also regulate neuronal functions and survival by modulating myelination and degradation of pathological toxic protein aggregates. Astrocytes have recently been proposed to possess both autophagic activity and active phagocytic capability which largely depend on sufficiently acidified lysosomes for complete degradation of cellular cargos. Defective lysosomal acidification in astrocytes impairs their autophagic and phagocytic functions, resulting in the accumulation of cellular debris, excessive myelin and lipids, and toxic protein aggregates, which ultimately contributes to the propagation of neuroinflammation and neurodegenerative pathology. Restoration of lysosomal acidification in impaired astrocytes represent new neuroprotective strategy and therapeutic direction. In this review, we summarize pathogenic factors, including neuroinflammatory signaling, metabolic stressors, myelin and lipid mediated toxicity, and toxic protein aggregates, that contribute to lysosomal acidification impairment and associated autophagic and phagocytic dysfunction in astrocytes. We discuss the role of lysosomal acidification dysfunction in astrocyte-mediated neuroinflammation primarily in the context of neurodegenerative diseases along with other brain injuries. We then highlight re-acidification of impaired lysosomes as a therapeutic strategy to restore autophagic and phagocytic functions as well as lysosomal degradative capacity in astrocytes. We conclude by providing future perspectives on the role of astrocytes as phagocytes and their crosstalk with other CNS cells to impart neurodegenerative or neuroprotective effects.

Astragaloside IV Relieves Central Sensitization by Regulating Astrocytic ROS/NF-κB Nuclear Translocation Signaling in Chronic Migraine Male Rats

Chronic migraine (CM) is a disabling neurological disease. Astragaloside IV (AS-IV), a natural product derived from Astragalus membranaceus , shows great potential in treating chronic pain by relieving inflammation and oxidative stress. This study aimed to investigate the effects and mechanisms of action of AS-IV on CM. An inflammatory soup comprising histamine, bradykinin, serotonin, and prostaglandin E2 was used to establish a CM rat model, while lipopolysaccharide was applied to induce an inflammatory response in primary astrocytes. Pain threshold measurements were used to evaluate nociceptive hypersensitivity, while qPCR and Western blotting were applied to detect inflammatory indicators and synaptic protein expression, and Golgi-Cox staining was applied to observe dendritic spine density, while transmission electron microscopy was used to observe synaptic ultrastructure. Mitochondrial function and oxidative stress were assessed using JC-1 staining, Mitotracker staining, reactive oxygen species (ROS) quantification, and glutathione content. AS-IV pretreatment alleviated central sensitization and ameliorated astrocyte activation and neuroinflammation. AS-IV pretreatment alleviated mitochondrial dysfunction in vitro, and reduced the nuclear translocation of NF-κB and the production of IL-1β, which were reversed by ROS scavengers in vitro or mitochondrial respiratory chain disruptors in vivo. Our study indicates that AS-IV can inhibit neuroinflammation by alleviating astrocyte mitochondrial dysfunction to mitigate central sensitization in CM, thereby providing an experimental basis for AS-IV and A. membranaceus in CM prevention and treatment.

Ligand-receptor interactions: A key to understanding microglia and astrocyte roles in epilepsy

Epilepsy continues to pose significant social and economic challenges on a global scale. Existing therapeutic approaches predominantly revolve around neurocentric mechanisms, and fail to control seizures in approximately one-third of patients. This underscores the pressing need for novel and complementary treatment approaches to address this gap. An increasing body of literature points to a role for glial cells, including microglia and astrocytes, in the pathogenesis of epilepsy. Notably, microglial cells, which serve as pivotal inflammatory mediators within the epileptic brain, have received increasing attention over recent years. These immune cells react to epileptogenic insults, regulate neuronal processes, and play diverse roles during the process of epilepsy development. Additionally, astrocytes, another integral non-neuronal brain cells, have garnered increasing recognition for their dynamic contributions to the pathophysiology of epilepsy. Their complex interactions with neurons and other glial cells involve modulating synaptic activity and neuronal excitability, thereby influencing the aberrant networks formed during epileptogenesis. This review explores the alterations in microglial and astrocytic function and their mechanisms of communication following an epileptogenic insult, examining their contribution to epilepsy development. By comprehensively studying these mechanisms, potential avenues could emerge for refining therapeutic strategies and ameliorating the impact of this complex neurological disease.

VEGFD/VEGFR3 signaling contributes to the dysfunction of the astrocyte IL-3/microglia IL-3Rα cross-talk and drives neuroinflammation in mouse ischemic stroke

Astrocyte-derived IL-3 activates the corresponding receptor IL-3Rα in microglia. This cross-talk between astrocytes and microglia ameliorates the pathology of Alzheimer's disease in mice. In this study we investigated the role of IL-3/IL-3Rα cross-talk and its regulatory mechanisms in ischemic stroke. Ischemic stroke was induced in mice by intraluminal occlusion of the right middle cerebral artery (MCA) for 60 min followed by reperfusion (I/R). Human astrocytes or microglia subjected to oxygen-glucose deprivation and reoxygenation (OGD/Re) were used as in vitro models of brain ischemia. We showed that both I/R and OGD/Re significantly induced decreases in astrocytic IL-3 and microglial IL-3Rα protein levels, accompanied by pro-inflammatory activation of A1-type astrocytes and M1-type microglia. Importantly, astrocyte-derived VEGFD acting on VEGFR3 of astrocytes and microglia contributed to the cross-talk dysfunction and pro-inflammatory activation of the two glial cells, thereby mediating neuronal cell damage. By using metabolomics and multiple biochemical approaches, we demonstrated that IL-3 supplementation to microglia reversed OGD/Re-induced lipid metabolic reprogramming evidenced by upregulated expression of CPT1A, a rate-limiting enzyme for the mitochondrial β-oxidation, and increased levels of glycerophospholipids, the major components of cellular membranes, causing reduced accumulation of lipid droplets, thus reduced pro-inflammatory activation and necrosis, as well as increased phagocytosis of microglia. Notably, exogenous IL-3 and the VEGFR antagonist axitinib reestablished the cross-talk of IL-3/IL-3Rα, improving microglial lipid metabolic levels via upregulation of CPT1A, restoring microglial phagocytotic function and attenuating microglial pro-inflammatory activation, ultimately contributing to brain recovery from I/R insult. Our results demonstrate that VEGFD/VEGFR3 signaling contributes to the dysfunction of the astrocyte IL-3/microglia IL-3Rα cross-talk and drives pro-inflammatory activation, causing lipid metabolic reprogramming of microglia. These insights suggest VEGFR3 antagonism or restoring IL-3 levels as a potential therapeutic strategy for ischemic stroke.

The aqueous extract of Armadillidium vulgare Latreille alleviates neuropathic pain via inhibiting neuron-astrocyte crosstalk mediated by the IL-12-IFN-γ-IFNGR-CXCL10 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Armadillidium vulgare Latreille (AV), the dried body of pillbug, was originally described in Shennong's Classic of Materia Medica. As a common analgesic in animal-based traditional Chinese medicine, it is mainly used to relieve pain, promoting diuresis, relieving fatigue and so on. Our work demonstrated that AV could alleviate various types of acute and chronic pain including neuropathic pain (NP). And transcriptome sequencing analysis revealed that AV could suppress CXCL10 to alleviate NP, however, the upstream mechanisms governing CXCL10 synthesis remain vague.

AIM OF THE STUDY

The research's goal was to identify the mechanism via which AV regulates CXCL10 to ameliorate NP.

MATERIALS AND METHODS

Chronic constriction injury (CCI) to the sciatic nerve was used to induce the NP model 14 days following surgery. To identify cell signaling pathways, various approaches were used, including transcriptome sequencing, western blotting, immunofluorescence, as well as ELISA. The in vitro assay involved the cultivation of neuron PC12 cells and astrocyte C6 cells.

RESULTS

Both in vivo and in vitro results demonstrated that IL-12/IL-18 enhanced IFN-γ production in spinal neurons, which acted on IFN-γ receptors on neurons and astrocytes to upregulate CXCL10 expression in these cells, illustrating the pivotal role of IL-12 in the crosstalk between neurons and astrocytes. The role of IL-12 in pain regulation was elucidated for the first time within the nervous system. Additionally, its synergistic interaction with IL-18 on the downstream IFN-γ-CXCL10 pathway dramatically altered the activation of neurons and astrocytes. And AV could suppress CXCL10 to alleviate NP by mediating the IL-12-IFN-γ-IFNGR signaling pathway.

CONCLUSIONS

We explored a new target for NP by regulating neuron-astrocyte crosstalk and provided a theoretical basis for AV in clinical use.

Glia control experience-dependent plasticity in an olfactory critical period

Sensory experience during developmental critical periods has lifelong consequences for circuit function and behavior, but the molecular and cellular mechanisms through which experience causes these changes are not well understood. The Drosophila antennal lobe houses synapses between olfactory sensory neurons (OSNs) and downstream projection neurons (PNs) in stereotyped glomeruli. Many glomeruli exhibit structural plasticity in response to early-life odor exposure, indicating a general sensitivity of the fly olfactory circuitry to early sensory experience. We recently found that glia shape antennal lobe development in young adults, leading us to ask if glia also drive experience-dependent plasticity during this period. Here, we define a critical period for structural and functional plasticity of OSN-PN synapses in the ethyl butyrate (EB)-sensitive glomerulus VM7. EB exposure for the first 2 days post-eclosion drives large-scale reductions in glomerular volume, presynapse number, and post- synaptic activity. Crucially, pruning during the critical period has long-term consequences for circuit function since both OSN-PN synapse number and spontaneous activity of PNs remain persistently decreased following early-life odor exposure. The highly conserved engulfment receptor Draper is required for this critical period plasticity as ensheathing glia upregulate Draper, invade the VM7 glomerulus, and phagocytose OSN presynaptic terminals in response to critical-period EB exposure. Loss of Draper fully suppresses the morphological and physiological consequences of critical period odor exposure, arguing that phagocytic glia engulf intact synaptic terminals. These data demonstrate experience-dependent pruning of synapses and argue that Drosophila olfactory circuitry is a powerful model for defining the function of glia in critical period plasticity.

Astrocyte-Derived Interleukin 11 Modulates Astrocyte-Microglia Crosstalk via Nuclear Factor-κB Signaling Pathway in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a severe and frequent septic complication, characterized by neuronal damage as key pathological features. The astrocyte-microglia crosstalk in the central nervous system (CNS) plays important roles in various neurological diseases. However, how astrocytes interact with microglia to regulate neuronal injury in SAE is poorly defined. In this study, we aim to investigate the molecular basis of the astrocyte-microglia crosstalk underlying SAE pathogenesis and also to explore the new therapeutic strategies targeting this crosstalk in this devastating disease. We established a human astrocyte/microglia coculture system on a microfluidic device, which allows real-time and high-resolution recording of glial responses to inflammatory stimuli. Based on this microfluidic system, we can test the responses of astrocytes and microglia to lipopolysaccharide (LPS) treatment, and identify the molecular cues that mediate the astrocyte-microglia crosstalk underlying the pathological condition. In addition, the SAE mouse model was utilized to determine the state of glial cells and evaluate the therapeutic effect of drugs targeting the astrocyte-microglia crosstalk in vivo. Here, we found that activated astrocytes and microglia exhibited close spatial interaction in the SAE mouse model. Upon LPS exposure for astrocytes, we detected that more microglia migrated to the central astrocyte culture compartment on the microfluidic device, accompanied by M1 polarization and increased cell motility in microglia. Cytokine array analysis revealed that less interleukin 11 (IL11) was secreted by astrocytes following LPS treatment, which further promoted reprogramming of microglia to pro-inflammatory M1 phenotype via the nuclear factor-κB (NF-κB) signaling pathway. Intriguingly, we found that IL11 addition markedly rescued LPS-induced neuronal injuries on the microfluidic system and brain injury in the SAE mouse model. This study defines an unknown crosstalk of astrocyte-microglia mediated by IL11, which contributed to the neuropathogenesis of SAE, and suggested a potential therapeutic value of IL11 in the devastating disease.

Exploring neuroglial signaling: diversity of molecules implicated in microglia-to-astrocyte neuroimmune communication

Effective communication between different cell types is essential for brain health, and dysregulation of this process leads to neuropathologies. Brain glial cells, including microglia and astrocytes, orchestrate immune defense and neuroimmune responses under pathological conditions during which interglial communication is indispensable. Our appreciation of the complexity of these processes is rapidly increasing due to recent advances in molecular biology techniques, which have identified numerous phenotypic states of both microglia and astrocytes. This review focuses on microglia-to-astrocyte communication facilitated by secreted neuroimmune modulators. The combinations of interleukin (IL)-1α, tumor necrosis factor (TNF), plus complement component C1q as well as IL-1β plus TNF are already well-established microglia-derived stimuli that induce reactive phenotypes in astrocytes. However, given the large number of inflammatory mediators secreted by microglia and the rapidly increasing number of distinct functional states recognized in astrocytes, it can be hypothesized that many more intercellular signaling molecules exist. This review identifies the following group of cytokines and gliotransmitters that, while not established as interglial mediators yet, are known to be released by microglia and elicit functional responses in astrocytes: IL-10, IL-12, IL-18, transforming growth factor (TGF)-β, interferon (IFN)-γ, C-C motif chemokine ligand (CCL)5, adenosine triphosphate (ATP), l-glutamate, and prostaglandin E2 (PGE2). The review of molecular mechanisms engaged by these mediators reveals complex, partially overlapping signaling pathways implicated in numerous neuropathologies. Additionally, lack of human-specific studies is identified as a significant knowledge gap. Further research on microglia-to-astrocyte communication is warranted, as it could discover novel interglial signaling-targeted therapies for diverse neurological disorders.

C3/C3aR Bridges Spinal Astrocyte-Microglia Crosstalk and Accelerates Neuroinflammation in Morphine-Tolerant Rats

AIMS

Communication within glial cells acts as a pivotal intermediary factor in modulating neuroimmune pathology. Meanwhile, an increasing awareness has emerged regarding the detrimental role of glial cells and neuroinflammation in morphine tolerance (MT). This study investigated the influence of crosstalk between astrocyte and microglia on the evolution of morphine tolerance.

METHODS

Sprague-Dawley rats were intrathecally treated with morphine twice daily for 9 days to establish morphine-tolerant rat model. Tail-flick latency test was performed to identify the analgesic effect of morphine. The role of microglia, astrocyte and C3-C3aR axis in morphine tolerance were elucidated by real-time quantitative polymerase chain reaction, Western blot, and immunofluorescence.

RESULTS

Chronic morphine treatment notably promoted the activation of microglia, upregulated the production of proinflammatory mediators (interleukin-1 alpha (IL-1α), tumor necrosis factor alpha (TNFα), and complement component 1q (C1q)). Simultaneously, it programed astrocytes to a pro-inflammatory phenotype (A1), which mainly expresses complement 3 (C3) and serping1. PLX3397 (a colony-stimulating factor 1 receptor (CSF1R) inhibitor), Compstain (a C3 inhibitor) and SB290157(a C3aR antagonist) could reverse the above pathological process and alleviate morphine tolerance to different extents.

CONCLUSION

Our findings identify C3-C3aR axis as an amplifier of microglia-astrocyte crosstalk, neuroinflammation and a node for therapeutic intervention in morphine tolerance.

The protective effects of gastrodin on neurological disorders: an update and future perspectives

Neurological disorders are characterized by high mortality and disability rates. Furthermore, the burden associated with disability and mortality resulting from neurological disorders has been increasing at an alarming rate. Botanical drugs and their bioactive components have emerged as a prominent area of research, offering a promising avenue for developing novel alternatives for treating neurological diseases. Gastrodin is the principal active component derived from the traditional Chinese medicinal plant Gastrodia elata Blume (GEB). Existing literature reveals that gastrodin exerts various pharmacological protective actions against neurological disorders. This review aimed to collate novel literature on gastrodin for treating neurological disorders from Web of Science, PubMed, Embase and CNKI. The pharmacokinetics of gastrodin, its therapeutic role in neurological disorders, the main mechanisms of action and clinical application were addressed. Furthermore, a detailed overview of gastrodin drug delivery systems and physical enhancement methods was presented, offering invaluable insights into potential research and the extensive applications of gastrodin.

Unraveling the neuroprotective potential of scalp electroacupuncture in ischemic stroke: A key role for electrical stimulation

This study aims to explore the neuroprotective effects of scalp Electroacupuncture (EA) on ischemic stroke, with a specific focus on the role of electrical stimulation (ES). Employing a rat model of middle cerebral artery occlusion (MCAO), we used methods such as Triphenyl tetrazolium chloride staining, micro-CT scanning, Enzyme linked immunosorbent assay (ELISA), and immunofluorescence to assess the impacts of EA. We further conducted RNA-seq analysis and in vitro experiments with organotypic brain slices and cerebral organoids to explore the underlying mechanisms. Our research revealed that EA notably reduced cerebral infarct volume and improved regional cerebral blood flow in rats following MCAO. Micro-CT imaging showed improved vascular integrity in EA-treated groups. Histological analyses, including HE staining, indicated reduced brain tissue damage. ELISA demonstrated a decrease in pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, suggesting improved blood-brain barrier function. Immunofluorescence and Western blot analyses revealed that EA treatment significantly inhibited microglial and astrocytic overactivation. RNA-seq analysis of brain tissues highlighted a downregulation of immune pathways and inflammatory responses, confirming the neuroprotective role of EA. This was further corroborated by in vitro experiments using organotypic brain slices and cerebral organoids, which showcased the efficacy of electrical stimulation in reducing neuroinflammation and protecting neuronal cells. The study highlights the potential of scalp EA, particularly its ES component, in treating ischemic stroke. It provides new insights into the mechanisms of EA, emphasizing its efficacy in neuroprotection and modulation of neuroinflammation, and suggests avenues for optimized treatment strategies in stroke therapy.

The Neuroimmune System and the Cerebellum

The recognition that there is an innate immune system of the brain, referred to as the neuroimmune system, that preforms many functions comparable to that of the peripheral immune system is a relatively new concept and much is yet to be learned. The main cellular components of the neuroimmune system are the glial cells of the brain, primarily microglia and astrocytes. These cell types preform many functions through secretion of signaling factors initially known as immune factors but referred to as neuroimmune factors when produced by cells of the brain. The immune functions of glial cells play critical roles in the healthy brain to maintain homeostasis that is essential for normal brain function, to establish cytoarchitecture of the brain during development, and, in pathological conditions, to minimize the detrimental effects of disease and injury and promote repair of brain structure and function. However, dysregulation of this system can occur resulting in actions that exacerbate or perpetuate the detrimental effects of disease or injury. The neuroimmune system extends throughout all brain regions, but attention to the cerebellar system has lagged that of other brain regions and information is limited on this topic. This article is meant to provide a brief introduction to the cellular and molecular components of the brain immune system, its functions, and what is known about its role in the cerebellum. The majority of this information comes from studies of animal models and pathological conditions, where upregulation of the system facilitates investigation of its actions.

The role of astrocytes response triggered by hyperglycaemia during spinal cord injury

OBJECTIVE

This manuscript aimed to provide a comprehensive overview of the physiological, molecular, and cellular mechanisms triggered by reactive astrocytes (RA) in the context of spinal cord injury (SCI), with a particular focus on cases involving hyperglycaemia.

METHODS

The compilation of articles related to astrocyte responses in neuropathological conditions, with a specific emphasis on those related to SCI and hyperglycaemia, was conducted by searching through databases including Science Direct, Web of Science, and PubMed.

RESULTS AND CONCLUSIONS

This article explores the dual role of astrocytes in both neurophysiological and neurodegenerative conditions within the central nervous system (CNS). In the aftermath of SCI and hyperglycaemia, astrocytes undergo a transformation into RA, adopting a distinct phenotype. While there are currently no approved therapies for SCI, various therapeutic strategies have been proposed to alleviate the detrimental effects of RAs following SCI and hyperglycemia. These strategies show promising potential in the treatment of SCI and its likely comorbidities.

Mesencephalic Astrocyte-Derived Neurotrophic Factor (MANF) Mitigates Neuroinflammation and Cognitive Impairment by Modulating Glial Activation in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a severe neurological complication of sepsis, characterized by cognitive impairment and increased mortality. Owing to the established neuroprotective and immunomodulatory effects of Mesencephalic Astrocyte-derived Neurotrophic Factor (MANF) in a plethora of neurological disorders, our study aimed to investigate the role of MANF in SAE and evaluate its potential as a therapeutic target. Employing a cecal ligation and puncture (CLP) mouse model of sepsis, we analyzed MANF expression in the hippocampus and cortex, and evaluated the influence of intranasally administered recombinant human MANF (rhMANF) on symptoms of SAE. Our results disclosed a substantial increase in MANF protein levels within the hippocampus and cortex of septic mice, primarily found in neurons. Post-CLP surgical administration of rhMANF led to numerous favorable outcomes. Specifically, rhMANF therapy mitigated sepsis-induced behavioral deviations and cognitive impairments, as gauged by SHIRPA scores and Morris water maze tests, and enhanced survival rates in septic mice. These enhancements were concomitant with alterations in neuroinflammation and synaptic integrity. The rhMANF treatment attenuated activation of microglia and astrocytes in the hippocampus and cortex, as evidenced by diminished Iba-1 and GFAP positive cells. It also curtailed the generation of pro-inflammatory cytokines TNF-α and IL-6, and obstructed the p38 MAPK inflammatory pathway. Moreover, rhMANF sustained the expression of synaptic proteins PSD95 and SYN, and conserved neuronal integrity, as demonstrated by Nissl staining. In conclusion, our study underscores the potential of MANF as an innovative therapeutic target for SAE, emphasizing its anti-inflammatory and neuroprotective capabilities.

Astrocytes and Tinnitus

Tinnitus is correlated with anomalies of neural plasticity and has been found to be affected by inflammatory status. The current theories on tinnitus, although still somewhat incomplete, are based on maladaptive plasticity mechanisms. Astrocytes play a major role in both neural responses to inflammation and plasticity regulation; moreover, they have recently been discovered to encode "context" for neuronal circuits, which is similar to the "expectation" of Bayesian brain models. Therefore, this narrative review explores the possible and likely roles of astrocytes in the neural mechanisms leading to acute and chronic tinnitus.

Seizures Triggered by Systemic Administration of 4-Aminopyridine in Rats Lead to Acute Brain Glucose Hypometabolism, as Assessed by [18F]FDG PET Neuroimaging

4-aminopyridine (4-AP) is a non-selective blocker of voltage-dependent K+ channels used to improve walking in multiple sclerosis patients, and it may be useful in the treatment of cerebellar diseases. In animal models, 4-AP is used as a convulsant agent. When administered intrahippocampally, 4-AP induces acute local glucose hypermetabolism and significant brain damage, while i.p. administration causes less neuronal damage. This study aimed to investigate the effects of a single i.p. administration of 4-AP on acute brain glucose metabolism as well as on neuronal viability and signs of neuroinflammation 3 days after the insult. Brain glucose metabolism was evaluated by [18F]FDG PET neuroimaging. [18F]FDG uptake was analyzed based on volumes of interest (VOIs) as well as by voxel-based (SPM) analyses. The results showed that independently of the type of data analysis used (VOIs or SPM), 4-AP induced acute generalized brain glucose hypometabolism, except in the cerebellum. Furthermore, the SPM analysis normalized by the whole brain uptake revealed a significant cerebellar hypermetabolism. The neurohistochemical assays showed that 4-AP induced hippocampal astrocyte reactivity 3 days after the insult, without inducing changes in neuronal integrity or microglia-mediated neuroinflammation. Thus, acute brain glucose metabolic and neuroinflammatory profiles in response to i.p. 4-AP clearly differed from that reported for intrahippocampal administration. Finally, the results suggest that the cerebellum might be more resilient to the 4-AP-induced hypometabolism.

A critical role for microglia in regulating metabolic homeostasis and neural repair after spinal cord injury

Traumatic spinal cord injury (SCI) often results in severe immune and metabolic disorders, aggravating neurological damage and inhibiting locomotor functional recovery. Microglia, as resident immune cells of the spinal cord, play crucial roles in maintaining neural homeostasis under physiological conditions. However, the precise role of microglia in regulating immune and metabolic functions in SCI is still unclear and is easily confused with that of macrophages. In this study, we pharmacologically depleted microglia to explore the role of microglia after SCI. We found that microglia are beneficial for the recovery of locomotor function. Depleting microglia disrupted glial scar formation, reducing neurogenesis and angiogenesis. Using liquid chromatography tandem mass spectrometry (LC‒MS/MS), we discovered that depleting microglia significantly inhibits lipid metabolism processes such as fatty acid degradation, unsaturated fatty acid biosynthesis, glycophospholipid metabolism, and sphingolipid metabolism, accompanied by the accumulation of multiple organic acids. Subsequent studies demonstrated that microglial depletion increased the inhibition of FASN after SCI. FASN inhibition exacerbated malonyl-CoA accumulation and significantly impeded the activity of mTORC1. Moreover, microglial depletion exacerbated the oxidative stress of neurons. In summary, our results indicate that microglia alleviate neural damage and metabolic disorders after SCI, which is beneficial for achieving optimal neuroprotection and neural repair.

Regulation of disease-associated microglia in the optic nerve by lipoxin B4 and ocular hypertension

BACKGROUND

The resident astrocyte-retinal ganglion cell (RGC) lipoxin circuit is impaired during retinal stress, which includes ocular hypertension-induced neuropathy. Lipoxin B4 produced by homeostatic astrocytes directly acts on RGCs to increase survival and function in ocular hypertension-induced neuropathy. RGC death in the retina and axonal degeneration in the optic nerve are driven by the complex interactions between microglia and macroglia. Whether LXB4 neuroprotective actions include regulation of other cell types in the retina and/or optic nerve is an important knowledge gap.

METHODS

Cellular targets and signaling of LXB4 in the retina were defined by single-cell RNA sequencing. Retinal neurodegeneration was induced by injecting silicone oil into the anterior chamber of mouse eyes, which induced sustained and stable ocular hypertension. Morphological characterization of microglia populations in the retina and optic nerve was established by MorphOMICs and pseudotime trajectory analyses. The pathways and mechanisms of action of LXB4 in the optic nerve were investigated using bulk RNA sequencing. Transcriptomics data was validated by qPCR and immunohistochemistry. Differences between experimental groups were assessed by Student's t-test and one-way ANOVA.

RESULTS

Single-cell transcriptomics identified microglia as a primary target for LXB4 in the healthy retina. LXB4 downregulated genes that drive microglia environmental sensing and reactivity responses. Analysis of microglial function revealed that ocular hypertension induced distinct, temporally defined, and dynamic phenotypes in the retina and, unexpectedly, in the distal myelinated optic nerve. Microglial expression of CD74, a marker of disease-associated microglia in the brain, was only induced in a unique population of optic nerve microglia, but not in the retina. Genetic deletion of lipoxin formation correlated with the presence of a CD74 optic nerve microglia population in normotensive eyes, while LXB4 treatment during ocular hypertension shifted optic nerve microglia toward a homeostatic morphology and non-reactive state and downregulated the expression of CD74. Furthermore, we identified a correlation between CD74 and phospho-phosphoinositide 3-kinases (p-PI3K) expression levels in the optic nerve, which was reduced by LXB4 treatment.

CONCLUSION

We identified early and dynamic changes in the microglia functional phenotype, reactivity, and induction of a unique CD74 microglia population in the distal optic nerve as key features of ocular hypertension-induced neurodegeneration. Our findings establish microglia regulation as a novel LXB4 target in the retina and optic nerve. LXB4 maintenance of a homeostatic optic nerve microglia phenotype and inhibition of a disease-associated phenotype are potential neuroprotective mechanisms for the resident LXB4 pathway.

Orexin-A Attenuates the Inflammatory Response in Sepsis-Associated Encephalopathy by Modulating Oxidative Stress and Inhibiting the ERK/NF-κB Signaling Pathway in Microglia and Astrocytes

BACKGROUND

Oxidative stress-induced inflammation is a major pathogenic mechanism in sepsis-associated encephalopathy (SAE). We hypothesized that regulation of reactive oxygen species (ROS) by the neuropeptide orexin-A could prevent SAE-induced oxidative stress and inflammation. Therefore, the aim of this study was to investigate the effects of orexin-A on oxidative stress and inflammation in SAE in mice.

METHODS

Adult male mice were treated with orexin-A (250 μg/kg, intranasal administration) to establish a cecal ligation perforation (CLP) model. We performed behavioral tests, observed neuronal damage in the hippocampal region, measured the levels of ROS, NOX2, and observed the structure of mitochondria by transmission electron microscopy. We then examined the inflammatory factors TNF-α and IL-1β, the activation of microglia and astrocytes, the expression of ERK/NF-κB, C3, and S100A10, and the presence of A1 type astrocytes and A2 type astrocytes.

RESULTS

Orexin-A treatment improved cognitive performance in CLP-induced SAE mice, attenuated neuronal apoptosis in the hippocampal region, ameliorated ROS levels and the extent of mitochondrial damage, and reduced protein expression of NOX2 in hippocampal tissue. In addition, orexin-A treatment significantly reduced microglia and astrocyte activation, inhibited the levels of P-ERK and NF-κB, and reduced the release of IL-1β and TNF-α, which were significantly increased after CLP. Finally, Orexin-A treatment significantly decreased the number of C3/glial fibrillary acidic protein (GFAP)-positive cells and increased the number of S100A10/GFAP-positive cells.

CONCLUSION

Our data suggest that orexin-A reduces ROS expression by inhibiting CLP-induced NOX2 production, thereby attenuating mitochondrial damage and neuronal apoptosis. Its inhibition of microglial and A1-type astrocyte activation and inflammation was associated with the ERK/NF-κB pathway. These suggest that orexin-A may reduce cognitive impairment in SAE by reducing oxidative stress-induced inflammation.

Mechanisms and therapeutic targets of carbon monoxide poisoning: A focus on reactive oxygen species

Carbon monoxide (CO) poisoning presents a substantial public health challenge that necessitates the identification of its pathological mechanisms and therapeutic targets. CO toxicity arises from tissue hypoxia-ischemia secondary to carboxyhemoglobin formation, and cellular damage mediated by CO at the cellular level. The mitochondria are the major targets of neuronal damage caused by CO. Under normal physiological conditions, mitochondria produce reactive oxygen species (ROS), which are byproducts of aerobic metabolism. While low ROS levels are crucial for essential cellular functions, including signal transduction, differentiation, responses to hypoxia and immunity, transcriptional regulation, and autophagy, excess ROS become pathological and exacerbate CO poisoning. This review presents the evidence of elevated ROS being associated with the progression of CO poisoning. Antioxidant treatments targeting ROS removal have been proven effective in mitigating CO poisoning, underscoring their therapeutic potential. In this review, we highlight the latest advances in the understanding of the role and the clinical implications of ROS in CO poisoning. We focus on cellular sources of ROS, the molecular mechanisms underlying mitochondrial oxidative stress, and potential therapeutic strategies for targeting ROS in CO poisoning.

Regulation of Diseases-Associated Microglia in the Optic Nerve by Lipoxin B4 and Ocular Hypertension

Background

The resident astrocyte-retinal ganglion cell (RGC) lipoxin circuit is impaired during retinal stress, which includes ocular hypertension-induced neuropathy. Lipoxin B4 produced by homeostatic astrocytes directly acts on RGCs to increase survival and function in ocular hypertension-induced neuropathy. RGC death in the retina and axonal degeneration in the optic nerve are driven by the complex interactions between microglia and macroglia. Whether LXB4 neuroprotective actions include regulation of other cell types in the retina and/or optic nerve is an important knowledge gap.

Methods

Cellular targets and signaling of LXB4 in the retina were defined by single-cell RNA sequencing. Retinal neurodegeneration was induced by injecting silicone oil into the anterior chamber of the mouse eyes, which induced sustained and stable ocular hypertension. Morphological characterization of microglia populations in the retina and optic nerve was established by MorphOMICs and pseudotime trajectory analyses. The pathways and mechanisms of action of LXB4 in the optic nerve were investigated using bulk RNA sequencing. Transcriptomics data was validated by qPCR and immunohistochemistry. Differences between experimental groups were assessed by Student's t-test and one-way ANOVA.

Results

Single-cell transcriptomics identified microglia as a primary target for LXB4 in the healthy retina. LXB4 downregulated genes that drive microglia environmental sensing and reactivity responses. Analysis of microglial function revealed that ocular hypertension induced distinct, temporally defined, and dynamic phenotypes in the retina and, unexpectedly, in the distal myelinated optic nerve. Microglial expression of CD74, a marker of disease-associated microglia in the brain, was only induced in a unique population of optic nerve microglia, but not in the retina. Genetic deletion of lipoxin formation correlated with the presence of a CD74 optic nerve microglia population in normotensive eyes, while LXB4 treatment during ocular hypertension shifted optic nerve microglia toward a homeostatic morphology and non-reactive state and downregulated the expression of CD74. Furthermore, we identified a correlation between CD74 and phospho-phosphoinositide 3-kinases (p-PI3K) expression levels in the optic nerve, which was reduced by LXB4 treatment.

Conclusion

We identified early and dynamic changes in the microglia functional phenotype, reactivity, and induction of a unique CD74 microglia population in the distal optic nerve as key features of ocular hypertension-induced neurodegeneration. Our findings establish microglia regulation as a novel LXB4 target in the retina and optic nerve. LXB4 maintenance of a homeostatic optic nerve microglia phenotype and inhibition of a disease-associated phenotype are potential neuroprotective mechanisms for the resident LXB4 pathway.

Glia control experience-dependent plasticity in an olfactory critical period

Sensory experience during developmental critical periods has lifelong consequences for circuit function and behavior, but the molecular and cellular mechanisms through which experience causes these changes are not well understood. The Drosophila antennal lobe houses synapses between olfactory sensory neurons (OSNs) and downstream projection neurons (PNs) in stereotyped glomeruli. Many glomeruli exhibit structural plasticity in response to early-life odor exposure, indicating a general sensitivity of the fly olfactory circuitry to early sensory experience. We recently found that glia shape antennal lobe development in young adults, leading us to ask if glia also drive experience-dependent plasticity during this period. Here we define a critical period for structural and functional plasticity of OSN-PN synapses in the ethyl butyrate (EB)-sensitive glomerulus VM7. EB exposure for the first two days post-eclosion drives large-scale reductions in glomerular volume, presynapse number, and post-synaptic activity. Crucially, pruning during the critical period has long-term consequences for circuit function since both OSN-PN synapse number and spontaneous activity of PNs remain persistently decreased following early-life odor exposure. The highly conserved engulfment receptor Draper is required for this critical period plasticity as ensheathing glia upregulate Draper, invade the VM7 glomerulus, and phagocytose OSN presynaptic terminals in response to critical-period EB exposure. Loss of Draper fully suppresses the morphological and physiological consequences of critical period odor exposure, arguing that phagocytic glia engulf intact synaptic terminals. These data demonstrate experience-dependent pruning of synapses and argue that Drosophila olfactory circuitry is a powerful model for defining the function of glia in critical period plasticity.

Early divergent modulation of NLRP2's and NLRP3's inflammasome sensors vs. AIM2's one by signals from Aβ·Calcium-sensing receptor complexes in human astrocytes

Alzheimer's disease (AD), the most prevalent human dementia, is driven by accruals of extracellular Aβ42 senile patches and intracellular neurofibrillary tangles of hyperphosphorylated Tau (p-Tau) proteins. AD's concurrent neuroinflammation is prompted by innate immunity-related cytosolic protein oligomers named inflammasomes. Upon proper "first" (priming) and "second" (activating) signals, inflammasomes overproduce proinflammatory Interleukin (IL)-1β, and IL-18 while cleaving pyroptosis-promoting Gasdermin D's N-terminal fragments. Our earlier studies highlighted that in pure monocultures, exogenous Aβ25-35-treated nonproliferating human cortical astrocytes (HCAs) made and released surpluses of endogenous Aβ42-oligomers (-os) and p-Tau-os, just as alike-treated human cortical neurons did. Aβ25-35-exposed HCAs also over-released NO, VEGFA, and IL-6. Aβ•CaSR (Aβ·Calcium-Sensing Receptor) complexes generated intracellular signals mediating all such neurotoxic effects since CaSR's negative allosteric modulators (aka NAMs or calcilytics, e.g., NPS2143) fully suppressed them. However, it had hitherto remained unexplored whether signals from Aβ·CaSR complexes also induced the early expression and/or activation of NOD-like 2 (NLRP2) and 3 (NLRP3) and of PYHIN absent in melanoma 2 (AIM2) inflammasomes in monocultured HCAs. To clarify this topic, we used in-situ-Proximity Ligation, qRT-PCR, double antibody arrays, immunoblots, and Caspase 1/4 enzymatic assays. Aβ·CaSR complexes quickly assembled on HCAs surface and issued intracellular signals activating Akt and JAK/STAT axes. In turn, the latter upregulated NLRP2 and NLRP3 PRRs (pattern recognition receptors) yet downregulated AIM2. These effects were specific, being significantly hindered by NPS2143 and inhibitors of PI3K (LY294002), AMPKα (Dorsomorphin), mTOR (Torin1), and JAK/TYK (Brepoticinib). A wide-spectrum inhibitor, Bay11-7082, intensified the Aβ·CaSR/Akt/JAK/STAT axis-driven opposite control of NLRP3's and AIM2's PRR proteins without affecting NLRP2 PRR upregulation. However, the said effects on the PRRs proteins vanished within 24-h. Moreover, Aβ·CaSR signals neither concurrently changed ASC, pro-IL-1β, and Gasdermin-D (holo- and fragments) protein levels and Caspases 1 and 4 enzymatic activities nor induced pyroptosis. Therefore, Aβ·CaSR cues acted as "first (priming) signals" temporarily increasing NLRP2 and NLRP3 PRRs expression without activating the corresponding inflammasomes. The neatly divergent modulation of NLRP3's vs. AIM2's PRR proteins by Aβ·CaSR cues and by Bay11-7082 suggests that, when bacterial or viral DNA fragments are absent, AIM2 might play "anti-inflammasomal" or other roles in HCAs. However, Bay11-7082's no effect on NLRP2 PRR overexpression also reveals that CaSR's downstream mechanisms controlling inflammasomes' sensors are quite complex in HCAs, and hence, given AD's impact on human health, well worth further studies.

Ulinastatin modulates NLRP3 inflammasome pathway in PTZ-induced epileptic mice: A potential mechanistic insight

Objective

The NLRP3 (NOD-like receptor family, pyrin domain containing 3) inflammasome-driven immune-inflammatory response has been shown to play a critical role in epilepsy progression across multiple studies. While Ulinastatin (UTI), an immunomodulatory agent known to target the NLRP3 pathway in neurological disorders, its implications in epilepsy have not been extensively studied. This investigation aims to explore UTI's role and underlying mechanisms in epilepsy.

Methods

To assess UTI's effects on epilepsy severity, neuroinflammation, and BBB integrity, a pentylenetetrazole (PTZ)-induced epilepsy model in mice and a co-culture system involving BV2 and HT22 cells stimulated by lipopolysaccharide (LPS) and ATP were employed. Techniques utilized included qPCR, Western blotting, ELISA, immunohistochemistry (IHC) staining, Evans Blue dye extravasation, glutamate assays, the Morris water maze, and Annexin V apoptosis assays.

Results

In the PTZ model, UTI administration led to a substantial decrease in seizure intensity and susceptibility, inhibited NLRP3 inflammasome activation, reduced neuroinflammatory interactions, lowered hippocampal and systemic inflammatory mediator levels, and improved cognitive performance. Furthermore, UTI upregulated claudin-5 expression, a tight junction protein in the endothelium, and diminished Evans Blue dye leakage, indicating improved BBB integrity. In BV2 and HT22 cell co-culture models, UTI exerted neuroprotective effects by mitigating microglia-mediated neurotoxicity and fostering neuronal recovery.

Conclusions

The findings demonstrate that UTI exerts transformative regulatory effects on the NLRP3 inflammasome in epilepsy models. This intervention effectively suppresses neuroinflammation, lessens seizure severity and susceptibility, and ameliorates epilepsy-related BBB dysfunction and cognitive impairments.

Multi-Protective Effects of Petunidin-3-O-(trans-p-coumaroylrutinoside)-5-O-glucoside on D-Gal-Induced Aging Mice

Petunidin-3-O-(trans-p-coumaroylrutinoside)-5-O-glucoside (PtCG), the primary anthocyanin ingredient in Lycium ruthenicum Murr., possesses a range of biological activities, including antioxidative properties and melanin inhibition. This study aimed to investigate the protective effect of PtCG on D-galactose (D-gal)-induced aging in female mice and elucidate the underlying molecular pathways. Behavioral experiments, including the MWW and Y-maze tests, revealed that PtCG significantly ameliorated cognitive decline and enhanced learning and memory abilities in aging mice. Regarding biochemical indicators, PtCG considerably improved superoxide dismutase (SOD) and glutathione (GSH) activity while reducing malondialdehyde (MDA) and acetylcholinesterase (AChE) levels in the hippocampus and serum. Furthermore, PtCG ingestion alleviated liver injury by decreasing alanine transaminase (ALT), aspartate transaminase (AST), and alkaline phosphatase (AKP) levels, and attenuated renal damage by reducing blood urea nitrogen (BUN) and uric acid (UA) levels. Transmission electron microscopy (TEM) results demonstrated that PtCG restored the function and quantity of synapses in the hippocampus. Hematoxylin and eosin (H&E), Masson's trichrome, and Nissl staining revealed that PtCG significantly improved the relevant pathological characteristics of liver and hippocampal tissues in aging mice. The molecular mechanism investigation showed that PtCG downregulated the protein expression of microglial marker ionized calcium-binding adapter molecule 1 (Iba1), astrocytic marker glial fibrillary acidic protein (GFAP), β-secretase 1 (BACE-1), and amyloid-beta1-42 (Aβ1-42) in the hippocampus of aging mice. The protein expression of inflammatory pathway components, including nuclear factor-kappa B (NF-κB), cyclooxygenase-2 (COX2), inducible nitric oxide synthase (iNOS), and interleukin-1 beta (IL-1β), was also suppressed. These findings suggest that PtCG may possess anti-aging properties, with its mechanism of action potentially linked to the attenuation of neuroinflammation, oxidative stress, and liver and kidney damage. PtCG may have future applications as a functional food for the treatment of aging-related disorders.

The Hidden Dangers of Sedentary Living: Insights into Molecular, Cellular, and Systemic Mechanisms

With the aging of the global population, neurodegenerative diseases are emerging as a major public health issue. The adoption of a less sedentary lifestyle has been shown to have a beneficial effect on cognitive decline, but the molecular mechanisms responsible are less clear. Here we provide a detailed analysis of the complex molecular, cellular, and systemic mechanisms underlying age-related cognitive decline and how lifestyle choices influence these processes. A review of the evidence from animal models, human studies, and postmortem analyses emphasizes the importance of integrating physical exercise with cognitive, multisensory, and motor stimulation as part of a multifaceted approach to mitigating cognitive decline. We highlight the potential of these non-pharmacological interventions to address key aging hallmarks, such as genomic instability, telomere attrition, and neuroinflammation, and underscore the need for comprehensive and personalized strategies to promote cognitive resilience and healthy aging.

Neuroprotection elicited by taurine in sporadic Alzheimer-like disease: benefits on memory and control of neuroinflammation in the hippocampus of rats

This study aimed to analyze whether taurine has a nootropic effect on short-term and long-term memory in a model of sporadic dementia of the Alzheimer's type (SDAT). Moreover, we evaluated the immunoreactivity and insulin receptor (IR) distribution and markers for neurons and glial cells in the hippocampus of rats with SDAT and treated with taurine. For this, Male Wistar rats received STZ (ICV, 3 mg/kg, bilateral, 5ul per site, aCFS vehicle) and were treated with taurine (100 mg/kg orally, 1 time per day, saline vehicle) for 25 days. The animals were divided into 4 groups: vehicle (VE), taurine (TAU), ICV-STZ (STZ) and ICV-STZ plus taurine (STZ + TAU). At the end of taurine treatment, short- and long-term memory were assessed by performance on object recognition and Y-maze tasks. Insulin receptor (IR) was evaluated by immunoperoxidase while mature neurons (NeuN), astrocytes (GFAP, S100B, SOX9), and microglia (Iba-1) were evaluated by immunofluorescence. STZ induced worse spatial and recognition memory (INDEX) in YM and ORT tasks. Taurine protected against STZ-induced memory impairment. SDAT reduced the population of mature neurons as well as increased astrocytic and microglial reactivity, and taurine protected against these STZ-induced effects, mainly in the CA1 region of the hippocampus. Taurine increases IR expression in the hippocampus, and protects against the reduction in the density of this receptor in CA1 induced by STZ. In conclusion, these findings demonstrate that taurine is able to enhance memory, up-regulates IR in the hippocampus, protects the neuron population, and reduces the astrogliosis found in SDAT.

Astrocytes and microglia in the coordination of CNS development and homeostasis

Glia have emerged as important architects of central nervous system (CNS) development and maintenance. While traditionally glial contributions to CNS development and maintenance have been studied independently, there is growing evidence that either suggests or documents that glia may act in coordinated manners to effect developmental patterning and homeostatic functions in the CNS. In this review, we focus on astrocytes, the most abundant glia in the CNS, and microglia, the earliest glia to colonize the CNS highlighting research that documents either suggestive or established coordinated actions by these glial cells in various CNS processes including cell and/or debris clearance, neuronal survival and morphogenesis, synaptic maturation, and circuit function, angio-/vasculogenesis, myelination, and neurotransmission. Some molecular mechanisms underlying these processes that have been identified are also described. Throughout, we categorize the available evidence as either suggestive or established interactions between microglia and astrocytes in the regulation of the respective process and raise possible avenues for further research. We conclude indicating that a better understanding of coordinated astrocyte-microglial interactions in the developing and mature brain holds promise for developing effective therapies for brain pathologies where these processes are perturbed.

Glial cell activation precedes neurodegeneration in the cerebellar cortex of the YG8-800 murine model of Friedreich ataxia

Friedreich ataxia is a hereditary neurodegenerative disorder resulting from reduced levels of the protein frataxin due to an expanded GAA repeat in the FXN gene. This deficiency causes progressive degeneration of specific neuronal populations in the cerebellum and the consequent loss of movement coordination and equilibrium, which are some of the main symptoms observed in affected individuals. Like in other neurodegenerative diseases, previous studies suggest that glial cells could be involved in the neurodegenerative process and disease progression in patients with Friedreich ataxia. In this work, we followed and characterized the progression of changes in the cerebellar cortex in the latest version of Friedreich ataxia humanized mouse model, YG8-800 (Fxnnull:YG8s(GAA)>800), which carries a human FXN transgene containing >800 GAA repeats. Comparative analyses of behavioral, histopathological, and biochemical parameters were conducted between the control strain Y47R and YG8-800 mice at different time points. Our findings revealed that YG8-800 mice exhibit an ataxic phenotype characterized by poor motor coordination, decreased body weight, cerebellar atrophy, neuronal loss, and changes in synaptic proteins. Additionally, early activation of glial cells, predominantly astrocytes and microglia, was observed preceding neuronal degeneration, as was increased expression of key proinflammatory cytokines and downregulation of neurotrophic factors. Together, our results show that the YG8-800 mouse model exhibits a stronger phenotype than previous experimental murine models, reliably recapitulating some of the features observed in humans. Accordingly, this humanized model could represent a valuable tool for studying Friedreich ataxia molecular disease mechanisms and for preclinical evaluation of possible therapies.

Astrocyte-Mediated Neuroinflammation in Neurological Conditions

Astrocytes are one of the key glial types of the central nervous system (CNS), accounting for over 20% of total glial cells in the brain. Extensive evidence has established their indispensable functions in the maintenance of CNS homeostasis, as well as their broad involvement in neurological conditions. In particular, astrocytes can participate in various neuroinflammatory processes, e.g., releasing a repertoire of cytokines and chemokines or specific neurotrophic factors, which result in both beneficial and detrimental effects. It has become increasingly clear that such astrocyte-mediated neuroinflammation, together with its complex crosstalk with other glial cells or immune cells, designates neuronal survival and the functional integrity of neurocircuits, thus critically contributing to disease onset and progression. In this review, we focus on the current knowledge of the neuroinflammatory responses of astrocytes, summarizing their common features in neurological conditions. Moreover, we highlight several vital questions for future research that promise novel insights into diagnostic or therapeutic strategies against those debilitating CNS diseases.

Glial Cells as Key Regulators in Neuroinflammatory Mechanisms Associated with Multiple Sclerosis

Even though several highly effective treatments have been developed for multiple sclerosis (MS), the underlying pathological mechanisms and drivers of the disease have not been fully elucidated. In recent years, there has been a growing interest in studying neuroinflammation in the context of glial cell involvement as there is increasing evidence of their central role in disease progression. Although glial cell communication and proper function underlies brain homeostasis and maintenance, their multiple effects in an MS brain remain complex and controversial. In this review, we aim to provide an overview of the contribution of glial cells, oligodendrocytes, astrocytes, and microglia in the pathology of MS during both the activation and orchestration of inflammatory mechanisms, as well as of their synergistic effects during the repair and restoration of function. Additionally, we discuss how the understanding of glial cell involvement in MS may provide new therapeutic targets either to limit disease progression or to facilitate repair.

M2 Microglia-derived Exosomes Promote Spinal Cord Injury Recovery in Mice by Alleviating A1 Astrocyte Activation

M2 microglia transplantation has previously demonstrated beneficial effects on spinal cord injury (SCI) by regulating neuroinflammation and enhancing neuronal survival. Exosomes (EXOs), secreted by almost all cell types, embody partial functions and properties of their parent cells. However, the effect of M2 microglia-derived EXOs (M2-EXOs) on SCI recovery and the underlying molecular mechanisms remain unclear. In this study, we isolated M2-EXOs and intravenously introduced them into mice with SCI. Considering the reciprocal communication between microglia and astroglia in both healthy and injured central nervous systems (CNSs), we subsequently focused on the influence of M2-EXOs on astrocyte phenotype regulation. Our findings indicated that M2-EXOs promoted neuron survival and axon preservation, reduced the lesion area, inhibited A1 astrocyte activation, and improved motor function recovery in SCI mice. Moreover, they inhibited the nuclear translocation of p65 and the activation of the NF-κB signalling pathway in A1 astrocytes. Therefore, our research suggests that M2-EXOs mitigate the activation of neurotoxic A1 astrocytes by inhibiting the NF-κB signalling pathway, thereby improving spinal tissue preservation and motor function recovery following SCI. This positions M2-EXOs as a promising therapeutic strategy for SCI.

Progress in the Pathogenesis of Diabetic Encephalopathy: The Key Role of Neuroinflammation

Diabetic encephalopathy (DE) is a severe complication that occurs in the central nervous system (CNS) and leads to cognitive impairment. DE involves various pathophysiological processes, and its pathogenesis is still unclear. This review summarised current research on the pathogenesis of diabetic encephalopathy, which involves neuroinflammation, oxidative stress, iron homoeostasis, blood-brain barrier disruption, altered gut microbiota, insulin resistance, etc. Among these pathological mechanisms, neuroinflammation has been focused on. This paper summarises some of the molecular mechanisms involved in neuroinflammation, including the Mammalian Target of Rapamycin (mTOR), Lipocalin-2 (LCN-2), Pyroptosis, Advanced Glycosylation End Products (AGEs), and some common pro-inflammatory factors. In addition, we discuss recent advances in the study of potential therapeutic targets for the treatment of DE against neuroinflammation. The current research on the pathogenesis of DE is progressing slowly, and more research is needed in the future. Further study of neuroinflammation as a mechanism is conducive to the discovery of more effective treatments for DE in the future.

The functions of exosomes targeting astrocytes and astrocyte-derived exosomes targeting other cell types

Astrocytes are the most abundant glial cells in the central nervous system; they participate in crucial biological processes, maintain brain structure, and regulate nervous system function. Exosomes are cell-derived extracellular vesicles containing various bioactive molecules including proteins, peptides, nucleotides, and lipids secreted from their cellular sources. Increasing evidence shows that exosomes participate in a communication network in the nervous system, in which astrocyte-derived exosomes play important roles. In this review, we have summarized the effects of exosomes targeting astrocytes and the astrocyte-derived exosomes targeting other cell types in the central nervous system. We also discuss the potential research directions of the exosome-based communication network in the nervous system. The exosome-based intercellular communication focused on astrocytes is of great significance to the biological and/or pathological processes in different conditions in the brain. New strategies may be developed for the diagnosis and treatment of neurological disorders by focusing on astrocytes as the central cells and utilizing exosomes as communication mediators.

Short-term behavioral and histological findings following a single concussive and repeated subconcussive brain injury in a rodent model

PRIMARY OBJECTIVE

It is unclear of the correlation between a mild traumatic brain injury (mTBI) and repeated subconcussive (RSC) impacts with respect to injury biomechanics. Thus, the present study was designed to determine the behavioral and histological differences between a single mTBI impact and RSC impacts with subdivided cumulative kinetic energies of the single mTBI impact.

RESEARCH DESIGN

Adult male Sprague-Dawley rats were randomly assigned to a single mTBI impact, RSC impact, sham, or repeated sham groups.

METHODS AND PROCEDURES

Following a weight drop injury, anxiety-like behavior and general locomotive activity and were assessed using the open field test, while motor coordination was evaluated using a rotarod unit. Neuronal loss, astrogliosis, and microgliosis were assessed using NeuN, GFAP and Iba-1 immunohistochemistry. All assessments were undertaken at 3- and 7-days post impact.

MAIN OUTCOMES AND RESULTS

No behavioral disturbances were observed in injury groups, however, both injury groups did lead to microgliosis following 3-days post-impact.

CONCLUSIONS

No pathophysiological differences were observed between a single mTBI impact and RSC impacts of the same energy input. Even though a cumulative injury threshold for RSC impacts was not determined, a threshold still may exist where no pathodynamic shift occurs.