Frontiers in Cellular Neuroscience最新文献

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease, the primary cause of dementia in people over 65 years old. AD is characterized by two molecular hallmarks, the intracellular neurofibrillary tangles of tau and amyloid beta oligomers, which are aggregates of hyperphosphorylated tau and amyloid beta peptides, respectively. These hallmarks gave rise to the two main theories that have opened the way for available treatments, such as FDA-approved memantine, and Aβ (aducanumab, lecanemab) and tau immunotherapies. Tau immunotherapy, especially multitarget approaches, has been recently proven effective. However, drugs against amyloid plaques had a non-successful outcome, despite their contributions to AD knowledge. An innovative approach comes from the multitarget concept, based on bioactive molecules and nutraceuticals. Interestingly, the use of early detection biomarkers such as Alz-Tau^®, SIMOA^®, and the recent Lumipulse™ test, are an important support to orient AD therapies based on the modifications of the styles of life. This includes physical exercise, a healthy diet, mindfulness, and cognitive stimulation, among others. All of the above analyses are critical to switch the focus to the prevention of AD.

Schwann cells are classically known as the constituent supporting cells of the peripheral nervous system. Beyond the scope of merely myelinating axons of the more saliently known neurons, Schwann cells comprise the majority of peripheral nervous system tissue. Through the lens of the inner ear, additional properties of Schwann cells are becoming elucidated. Therein, the process of myelin formation in development is more aptly understood as a homeostatic oscillation of differentiation status. Perpetual interaction between neural and non-neural cells of the inner ear maintains an intricate balance of guidance, growth, and maturation during development. In disease, aberration to Schwann cell myelination contributes to sensorineural hearing loss in conditions such as Guillain-Barre Syndrome and Charcot-Marie-Tooth disease, and tumorigenic over proliferation of Schwann cells defines vestibular schwannomas seen in neurofibromatosis type 2. Schwann cells demonstrate plasticity during oscillations between differentiation and dedifferentiation, a property that is now being leveraged in efforts to regenerate lost neurons. Emerging strategies of reprogramming, small molecule modulation, and gene therapy suggest that Schwann cells could serve as progenitor cells for regenerated neurons. Understanding the duality of Schwann cells in pathology and repair could transform the approach to treating sensorineural hearing loss.

Introduction: Multiplex immunofluorescence (mIF) utilizes distinct fluorophore-conjugated antibodies to enable the simultaneous visualization and quantification of multiple protein targets within a single tissue section. mIF allows high-resolution spatial mapping of cellular phenotypes within the native tissue microenvironment (TME). mIF facilitates the comprehensive analysis of complex biological systems, such as brain tumors, immune cell infiltration, and tissue heterogeneity. Laser interstitial thermal therapy (LITT) is a minimally invasive, hyperthermia-based laser cytoreductive method for the treatment of surgically inaccessible brain tumors, treatment-resistant epilepsy, and radiation necrosis. Laser-induced heat causes tissue damage, vascular leakage, and the appearance of heat-induced neo-antigens. There is an urgent clinical need to understand the elusive immunomodulatory roles of LITT in the brain TME. We describe a versatile, affordable, and customizable mIF method for the spatial imaging of multiple early tissue responses in post-LITT mouse brain.

Methods: We have developed a customizable and affordable mIF protocol that uses standard histological and microscopy equipment to assess TME changes in formalin-fixed paraffin-embedded (FFPE) mouse brain tissue sections. We combined mIF with a laser cytoreduction workflow that uses MRI to monitor laser-induced tissue damage in post-LITT normal and tumor murine brains. Multiplex IF on individual tissue sections enabled the simultaneous spatial image analysis of multiple cellular and molecular immunotargets, including resident brain cell responses and immune cell infiltration, as exemplified with a mouse brain TME on Day 10 post-LITT.

Results: We combined our mIF imaging procedure with in-vivo targeted laser-induced hyperthermic brain tissue ablation on FFPE mouse brain sections on Day 10 post-LITT. This enabled the spatial visualization of activation states of resident brain cells and the emergence and distribution of diverse phagocytic immune cell populations at the post-LITT site.

Conclusion: Multiplex IF on mouse models of laser cytoablation treatment in non-tumor and tumor brains offers a significant advancement by aiding in our understanding of repair and immune responses in post-LITT brains. Our customizable mIF protocol is cost-effective and simultaneously investigates the spatial distribution of multiple immune cell populations and the activation states of different resident brain cells in the post-LITT brain.

Introduction: This study investigates the neuroprotective role of growth hormone (GH) in modulating retinal inflammation and microglial responses following optic nerve crush (ONC) in male rats.

Methods: Retinal inflammation and microglial activation were assessed at 24 h and 14 days post-ONC, with or without GH treatment (0.5 mg/kg, subcutaneously, every 12 h). Gene and protein expression of inflammatory markers (e.g., IL-6, TNFα, Iba1, CD86, CD206) were evaluated using qPCR, ELISA, and Western blotting. Microglial morphology was quantified using skeleton and fractal analysis of Iba1-stained retinal sections. Retinal structure and function were assessed via fundus imaging and optomotor reflex testing.

Results: ONC induced significant increases in proinflammatory cytokines (IL-6, TNFα, IL-18) and microglial activation, characterized by reduced branching complexity and increased cell density. GH treatment significantly decreased proinflammatory cytokine levels, modulated microglial phenotype (CD86/CD206 expression), and preserved microglial morphology in the retina. Using the SIM-A9 microglial cell line, we further demonstrated that GH reduces NFκB pathway activation and suppresses LPS-induced proinflammatory cytokine production. At 14 days post-injury, GH-treated retinas exhibited reduced optic nerve size and improved optomotor responses, indicating both structural neuroprotection and functional recovery.

Discussion: Overall, GH mitigates ONC-induced retinal inflammation by reducing proinflammatory signaling and preserving microglial architecture, thereby protecting retinal integrity and function. These findings highlight the potential of GH as a therapeutic agent for retinal neurodegenerative conditions.

Functional neuronal connectivity relies on long-range propagation of action potentials by myelinated axons. This process critically depends on the distribution and biophysical properties of ion channels clustered at specialized, regularly spaced domains, the nodes of Ranvier, where the signals are actively regenerated. Morphological and functional evidence indicates that voltage-gated Na⁺ channels, which directly support action potential conduction, are exclusively localized at nodes. While these domains also contain voltage-gated Ca²⁺ channels that contribute to key intracellular signaling cascades, evidence regarding the presence of functional Ca²⁺ channels in the internodal regions remains conflicting. Using high-speed fluorescence imaging, we characterized action potential-evoked Na⁺ and Ca²⁺ dynamics at the nodes of Ranvier in myelinated axons of layer 5 pyramidal neurons in cortical brain slices. Spatially, both Na⁺ and Ca²⁺ elevations were largely restricted to the nodal regions. The time-to-peak of the nodal Na⁺ transients was significantly shorter (3.7 ± 0.3 ms) than that of the Ca²⁺ transients (10.3 ± 0.6 ms with OGB-1, 4.2 ± 0.5 ms with OGB-5 N), consistent with electrophysiological evidence indicating that Na⁺ influx occurs primarily during the action potential upstroke, whereas Ca²⁺ influx predominantly takes place during and after the repolarization phase. The decay of Na⁺ transients, reflecting lateral diffusion into the internodes, was exceptionally fast in short nodes and became progressively slower in longer ones, consistent with computational models assuming diffusion-based clearance alone. In contrast, Ca²⁺ transients decayed more slowly and showed no dependence on nodal length, consistent with clearance dominated by active transport. Finally, the post-spike recovery of nodal Na⁺ fluxes was rapid and temperature-dependent, consistent with the reactivation kinetics of voltage-gated Na⁺ channels. In contrast, the similarly rapid but temperature-independent recovery of Ca²⁺ flux suggests that a single action potential does not induce Ca²⁺ channel inactivation and therefore has minimal impact on their availability during subsequent spikes.

Olfactory dysfunction is increasingly recognized as an early, non-motor manifestation of multiple sclerosis (MS), but the mechanisms underlying its occurrence remain unclear. Using the rat model of experimental autoimmune encephalomyelitis (EAE), we investigated the temporal relationship between olfactory impairment, neuroinflammation, barrier integrity, and adenosine signaling in the olfactory bulb (OB) in the early stage of EAE. The study showed that more than two-thirds of EAE animals exhibited significant deficits in the buried food test as early as 3 days post-immunization (dpi), which preceded the first motor symptoms by several days. Open field test confirmed that these olfactory deficits were not due to impaired locomotion. Transient breach to the OB tissue barrier was demonstrated at 3-5 dpi by increased FITC-dextran penetration and peripheral monocyte/macrophage infiltration into the lateral aspect of the OB. The breach coincided with activation of microglia in the outer nerve layer on the lateral aspect of the OB. Oxidative stress, including elevated malondialdehyde, nitric oxide, and superoxide ion levels along with a depleted antioxidant defense system, indicated a redox imbalance, while a transient increase in neurofilament light chain serum levels at 3 dpi indicated acute neuroaxonal injury and barrier disruption at early stage EAE. At the molecular level, the simultaneous upregulation of CD73 and adenosine A₁/A_2A receptors along the pial surface and in the olfactory nerve layer suggested enhanced adenosine signaling in early barrier modulation. Spatial mapping of FITC-dextran penetration, peripheral infiltrates, and microglia activation indicated access of immune cells from the subarachnoid space into the OB parenchyma. Overall, these results demonstrate that the OB is a permissive entry zone for autoreactive immune cells in the OB in early stages of EAE, highlighting olfactory and behavioral testing as promising tools for early detection and monitoring of MS.

Kinesin superfamily proteins (KIFs) constitute a pivotal class of molecular motors that facilitate the intracellular transport of cellular "cargo." Their principal functions encompass the participation of the transport of cellular substances along microtubules, as well as the engagement in the formation of the mitotic spindle and the segregation of chromosomes during cellular mitosis. Dysregulation of KIFs expression can precipitate anomalies in intracellular material transport, mitotic abnormalities, aberrant cell proliferation and migration, and genomic instability within cells. Moreover, members of the KIFs are implicated in the proliferation of neural progenitor cells and the migration of neurons, which are critical processes in the development of the central nervous system. To date, an extensive body of research has substantiated the close correlation between mutations or aberrant expression of KIFs and the onset of neurological disorders, including neurotumors, neurodegenerative disease, and psychiatric illnesses. This review will synthesize recent research elucidating the nexus between KIFs and neurodevelopment, as well as their association with neurological diseases.

Background: Major depressive disorder (MDD) is a common chronic psychiatric disorder that affects individuals of all ages worldwide, causing significant impairment to patients' physical and mental health as well as social functioning. Vascular endothelial growth factor (VEGF), traditionally recognized as a regulator of angiogenesis and vascular permeability, has been identified in recent studies to possess neurotrophic and neuroprotective potential in the central nervous system (CNS) and is implicated in the pathological processes of MDD.

Aim: To systematically elaborate on the role of VEGF in the pathological mechanisms of MDD and its potential as a target for antidepressant therapy.

Key findings: Through interactions with its receptors (VEGFR1, VEGFR2, and VEGFR3), VEGF regulates critical pathways such as gene expression, blood-brain barrier (BBB) function, and brain-derived neurotrophic factor (BDNF), thereby establishing physiological and pathological associations with MDD. Its signaling pathway serves as a core target for various antidepressant treatments, including conventional antidepressants, ketamine, electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation (rTMS), and resolvins. Short-term upregulation of central VEGF may exert antidepressant effects by promoting the benign remodeling of neurovascular networks, and its subsequent return to baseline levels during treatment can avoid BBB damage, providing novel insights for the management of rapid-onset and treatment-resistant depression.

Conclusion: Vascular endothelial growth factor holds significant importance in the pathology and treatment of MDD. In-depth exploration of its regulatory mechanisms may provide a basis for the development of novel antidepressant therapies.

Introduction: The main genetic risk factor for Alzheimer's disease (AD) is the presence of the apolipoprotein E4 (APOE4) allele. While APOE4 increases the risk of developing AD, the APOE2 allele is protective and APOE3 is risk-neutral. In the brain, APOE is primarily expressed by astrocytes and plays a key role in various processes including cholesterol and lipid transport, neuronal growth, synaptic plasticity, immune response and energy metabolism. Disruptions in brain energy metabolism are considered a major contributor to AD pathophysiology, raising a key question about how different APOE isoforms affect the energy metabolism of human astrocytes.

Methods: In this study, we generated astrocytes (iAstrocytes) from APOE-isogenic human induced pluripotent stem cells (iPSCs), expressing either APOE2, APOE3, APOE4 or carrying an APOE knockout (APOE-KO), and investigated APOE genotype-dependent changes in energy metabolism.

Results: ATP Seahorse assay revealed a reduced mitochondrial and glycolytic ATP production in APOE4 iAstrocytes. In contrast, glycolysis stress tests demonstrated enhanced glycolysis and glycolytic capacity in APOE4 iAstrocytes while genetically encoded nanosensor-based FLIM analysis revealed that APOE does not affect lactate dynamics. In agreement with the increased glycolytic activity, APOE4 iAstrocytes also showed elevated mitochondrial respiration and activity, indicated by proteomic GO enrichment analysis and mitochondrial stress test. This was accompanied by elevated proton leak in APOE4 iAstrocytes while levels of mitochondrial uncoupling proteins (UCPs) were not affected. Mass spectrometry-based metabolomic analysis identified various energy and glucose metabolism-related pathways that were differentially regulated in APOE4 compared to the other genotypes, including mitochondrial electron transport chain (ETC) and glycolysis. In general, APOE2 and APOE-KO iAstrocytes showed a very similar phenotype in all functional assays and differences between APOE2/APOE-KO and APOE4 were stronger than between APOE3 and APOE4.

Discussion: Our study provides evidence for APOE genotype-dependent effects on astrocyte energy metabolism and highlights alterations in the bioenergetic processes of the brain as important pathomechanisms in AD.

Spinal cord injury (SCI) is a serious disorder that affects sensory, motor, and autonomic functions. Its pathological process is divided into two stages: primary and secondary injury. The secondary injury involves a variety of biological cascade reactions, leading to an imbalance in the spinal cord microenvironment. Non-coding RNAs (ncRNAs) play a crucial regulatory role in the pathophysiological process of spinal cord injury, including long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), all of which are involved in processes such as axonal regeneration, oxidative stress, inflammatory response, autophagy, and apoptosis. Although the pathophysiological process of spinal cord injury has been partially elucidated, its pathogenesis is not yet fully understood, and effective treatments are limited. This article reviews the regulatory role and molecular mechanisms of ncRNAs in the development and progression of spinal cord injury and proposes strategies for treating spinal cord injury by regulating ncRNAs.