Microglia emerge as central players in brain disease. Nat Med. 2017;23:1018-1027. [PMID: 28886007 DOI: 10.1038/nm.4397]

H4K12 lactylation-regulated NLRP3 is involved in cigarette smoke-accelerated Alzheimer-like pathology through mTOR-regulated autophagy and activation of microglia

Cigarette smoke (CS), an indoor environmental pollution, is an environmental risk factor for diverse neurological disorders. However, the neurotoxicological effects and mechanisms of CS on Alzheimer's disease (AD) progression remain unclear. We found that CS accelerated the progression of AD, including increasing β-amyloid (Aβ) plaque deposition and exacerbating cognitive decline. Mechanistically, CS exposure increased the levels of NOD-like receptor protein 3 (NLRP3), which impaired autophagic flux in microglia by activating the mammalian target of rapamycin (mTOR) signal. Metabolomics analysis revealed an upregulation of lactate levels and an increase in global protein lysine lactylation in the brain tissue of CS-exposed AD-transgenic mice. Immunoprecipitation-Mass Spectrometry and chromatin immunoprecipitation assays demonstrated that CS elevates H4K12 lactylation (H4K12la) levels, which accumulate at the promoter region of NLRP3, leading to the activation of its transcription. Via inhibiting lactate or NLRP3 activation, oxamate and MCC950 alleviates these CS-induced effects. Therefore, our data suggest that the CS-induced increase in lactate levels triggers NLRP3 transcriptional activation through H4K12la, which subsequently leads to mTOR-mediated autophagy dysfunction in microglia, promoting microglial activation and resulting in Aβ plaque accumulation in AD-transgenic mice. This provides a new mechanism and potential therapeutic target for AD associated with environmental factors.

CCL2/CCR2 signaling-mediated microglial migration leads to cerebral small vessel dysfunction in chronic hypertension model rats

Microglia are cerebral immune cells that maintain brain homeostasis; those that are juxtaposed to vessels are sometimes called vessel-associated microglia (VAM). Recent studies have indicated a role for VAM in maintaining blood-brain barrier integrity in different stages of diseases such as ischemic stroke and systemic inflammatory disease. Hypertension is a major cause of cerebral small vessel disease (CSVD) in humans. Recently, several reports reported that microglial activation in hypertensive animal models and our previous report indicated the increase in VAM from the early stage of chronic hypertension. However, the precise involvement of VAM in hypertensive CSVD remains unclear. In the present study, we used a deoxycorticosterone-acetate-salt chronic hypertensive rat model to demonstrate that signaling via CC motif chemokine ligand 2 (CCL2) and its receptor CC chemokine receptor type 2 (CCR2) is crucial for the increase in VAM. This signaling was associated with microglial migration toward vessels at the early disease stage. Moreover, the inhibition of this signaling resulted in reduced VAM numbers and the preservation of astrocytic endfeet in the late disease stage. Overall, CCL2/CCR2 signaling may be a trigger for microglial migration, leading to the development of CSVD, during chronic hypertension. This signaling is therefore a potential target for future preventive treatments.

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.

Comparative Analysis of HMC3 and C20 Microglial Cell Lines Reveals Differential Myeloid Characteristics and Responses to Immune Stimuli

Microglia are the primary resident immune cells of the central nervous system (CNS) that respond to injury and infections. Being critical to CNS homeostasis, microglia also have been shown to contribute to neurodegenerative diseases and brain cancer. Hence, microglia are regarded as a potential therapeutic target in CNS diseases, resulting in an increased demand for reliable in vitro models. Two human microglia cell lines (HMC3 and C20) are being used in multiple in vitro studies, however, the knowledge of their biological and immunological characteristics remains limited. Our aim was to identify and compare the biological changes in these immortalised immune cells under normal physiological and immunologically challenged conditions. Using high-resolution quantitative mass spectrometry, we have examined in-depth proteomic profiles of non-stimulated and LPS or IFN-γ challenged HMC3 and C20 cells. Our findings reveal that HMC3 cells responded to both treatments through upregulation of immune, metabolic, and antiviral pathways, while C20 cells showed a response associated with mitochondrial and immune activities. Additionally, the secretome analysis demonstrated that both cell lines release IL-6 in response to LPS, while IFN-γ treatment resulted in altered kynurenine pathway activity, highlighting distinct immune and metabolic adaptations.

Advancements in research on the thrombo-inflammation mechanisms mediated by factor XII in ischemic stroke

Ischemic stroke (IS) is a major cause of mortality and disability, with thrombo-inflammation constituting a core pathophysiological mechanism. This process is closely linked to coagulation cascade activation, endothelial injury, immune cell infiltration, and neuronal damage. Coagulation factor XII (FXII), a key mediator of the contact activation pathway, has emerged as a promising therapeutic target due to its dual role in pathological thrombosis and immune regulation, without compromising physiological hemostasis. However, the clinical translation of FXII-targeted therapies is hindered by paradoxical observations. Recent studies highlight that FXII's functional complexity stems from its structural and spatial heterogeneity: full-length FXII derived from the liver and short FXII mRNA isoforms expressed in neurons mediate distinct biological effects. While FXII contributes to neuroinflammation and vascular injury via endothelial-platelet-neutrophil interactions, neuron-derived FXII exhibits neuroprotective effects through HGF-mediated signaling pathways. Additionally, circulating FXIIa promotes vascular remodeling by enhancing endothelial growth factor (VEGF) release. This review summarizes the multifaceted regulatory mechanisms of FXII in IS, focusing on its structure, distribution, preclinical-clinical paradox, and current therapeutic strategies. Special emphasis is placed on its domain-specific functions and the neuroprotective effects of FXII.

Targeting hypoxia-related pathobiology in Alzheimer's disease: strategies for prevention and treatment

INTRODUCTION

Alzheimer's Disease (AD) is a neurodegenerative condition characterised by cognitive decline and memory impairment. Recent research highlights the important role of hypoxia, a state of insufficient oxygen availability, in exacerbating AD pathogenesis.

MATERIALS AND METHODS

Through the use of a number of different search engines like Scopus, PubMed, Bentham, and Elsevier databases, a literature review was carried out for investigating the role of hypoxia mediated pathobiology in AD. Only peerreviewed articles published in reputable journals in English language were included. Conversely, non-peer-reviewed articles, conference abstracts, and editorials were excluded, along with studies lacking experimental or clinical relevance or those unavailable in full text.

CONCLUSION

Hypoxia exacerbates core pathological features such as oxidative stress, neuroinflammation, mitochondrial dysfunction, amyloid-beta (Aβ) dysregulation, and hyperphosphorylation of tau protein. These interlinked mechanisms establish a self-perpetuating cycle of neuronal damage, accelerating disease progression. Addressing hypoxia as a modifiable risk factor offers potential for both prevention and treatment of AD. Exploring hypoxia and the HIF signalling pathway may help counteract the neuropathological and symptomatic effects of neurodegeneration.

Hippocampal microglial activation induces cognitive impairment and allodynia through neuronal plasticity changes in male mice with neuropathic pain

Clinical evidence indicates that cognitive impairment is a common comorbidity of chronic pain, including neuropathic pain, but the mechanism underlying this comorbidity remains unclear. Neuroinflammation plays a critical role in the development of both neuropathic pain and cognitive impairment. A previous study showed that minocycline, an inhibitor of microglia, ameliorated allodynia and cognitive impairment in partial sciatic nerve ligation (PSNL) mice. Therefore, the current study examined a potential role of brain microglia in allodynia and cognitive impairment in male mice with neuropathic pain due to PSNL. Immunohistochemistry of the microglial markers ionized calcium-binding adapter molecule 1 (Iba1), transmembrane protein 119 (TMEM119), and purinergic receptor P2Y12 (P2RY12) was performed to examine microglial status. Two weeks after PSNL, significant microglial activation was observed in the hippocampus and amygdala, but not in the perirhinal cortex. Inhibition of brain-region-specific microglia with a local microinjection of clodronate liposomes was examined to elucidate the involvement of these microglia in PSNL-induced allodynia and cognitive impairment. Local clodronate liposome microinjection to the hippocampus, but not the amygdala, ameliorated allodynia and cognitive impairment. Other changes in the hippocampus of PSNL mice, e.g., decreased hippocampal dendrite length and intersections number, were prevented by microinjection of clodronate liposomes. The current findings suggest hippocampal microglia are related to cognitive impairment and allodynia through neuronal plasticity changes observed in PSNL mice. Blocking hippocampal microglia-mediated neuroinflammation may be a novel approach for reducing comorbidities such as cognitive impairment associated with neuropathic pain.

Peripheral nervous system microglia-like cells regulate neuronal soma size throughout evolution

Microglia, essential in the central nervous system (CNS), were historically considered absent from the peripheral nervous system (PNS). Here, we show a PNS-resident macrophage population that shares transcriptomic and epigenetic profiles as well as an ontogenetic trajectory with CNS microglia. This population (termed PNS microglia-like cells) enwraps the neuronal soma inside the satellite glial cell envelope, preferentially associates with larger neurons during PNS development, and is required for neuronal functions by regulating soma enlargement and axon growth. A phylogenetic survey of 24 vertebrates revealed an early origin of PNS microglia-like cells, whose presence is correlated with neuronal soma size (and body size) rather than evolutionary distance. Consistent with their requirement for soma enlargement, PNS microglia-like cells are maintained in vertebrates with large peripheral neuronal soma but absent when neurons evolve to have smaller soma. Our study thus reveals a PNS counterpart of CNS microglia that regulates neuronal soma size during both evolution and ontogeny.

Progranulin deficiency in the brain: the interplay between neuronal and non-neuronal cells

Heterozygous mutations in GRN gene lead to insufficient levels of the progranulin (PGRN) protein, resulting in frontotemporal dementia (FTD) with TAR DNA-binding protein 43 (TDP-43) inclusions, classified pathologically as frontotemporal lobar degeneration (FTLD-TDP). Homozygous GRN mutations are exceedingly rare and cause neuronal ceroid lipofuscinosis 11, a lysosomal storage disease with onset in young adulthood, or an FTD syndrome with late-onset manifestations. In this review, we highlight the broad spectrum of clinical phenotypes associated with PGRN deficiency, including primary progressive aphasia and behavioral variant of frontotemporal dementia. We explore these phenotypes alongside relevant rodent and in vitro human models, ranging from the induced pluripotent stem cell-derived neural progenitors, neurons, microglia, and astrocytes to genetically engineered heterotypic organoids containing both neurons and astrocytes. We summarize advantages and limitations of these models in recapitulating the main FTLD-GRN hallmarks, highlighting the role of non-cell-autonomous mechanisms in the formation of TDP-43 pathology, neuroinflammation, and neurodegeneration. Data obtained from patients' brain tissues and biofluids, in parallel with single-cell transcriptomics, demonstrate the complexity of interactions among the highly heterogeneous cellular clusters present in the brain, including neurons, astrocytes, microglia, oligodendroglia, endothelial cells, and pericytes. Emerging evidence has revealed that PGRN deficiency is associated with cell cluster-specific, often conserved, genetic and molecular phenotypes in the central nervous system. In this review, we focus on how these distinct cellular populations and their dysfunctional crosstalk contribute to neurodegeneration and neuroinflammation in FTD-GRN. Specifically, we characterize the phenotypes of lipid droplet-accumulating microglia and alterations of myelin lipid content resulting from lysosomal dysfunction caused by PGRN deficiency. Additionally, we consider how the deregulation of glia-neuron communication affects the exchange of organelles such as mitochondria, and the removal of excess toxic products such as protein aggregates, in PGRN-related neurodegeneration.

Inhalable Ce Nanozyme-Backpacked Phage Aims at Ischemic Cerebral Injury by M1-Microglia Hitchhiking

There is a desperate need for precise nanomedications to treat ischemic cerebral injury. Yet, the drawbacks of poor delivery efficiency and off-target toxicity in pathologic parenchyma for traditional antioxidants against ischemic stroke result in inadequate brain accumulation. M13 bacteriophages are highly phagocytosed by M1-polarized microglia and can be carried toward the neuroinflammatory sites. Here, a bio-active, inhalable, Ce0.9Zr0.1O2-backpacked-M13 phage (abbreviated as CZM) is developed and demonstrates how M13 bacteriophages are taken up by different phenotypes' microglia. With the M1 microglia's proliferating and migrating, CZM can be extensively and specifically delivered to the site of the ischemic core and penumbra, where the surviving nerve cells need to be shielded from secondary oxidative stress and inflammatory cascade initiated by reactive oxygen species (ROS). With non-invasive administration, CZM effectively alleviates oxidative damage and apoptosis of neurons by eliminating ROS generated by hyperactive M1-polarized microglia. Here, a secure and effective strategy for the targeted therapy of neuroinflammatory maladies is offered by this research.

The roles of immune factors in neurodevelopment

The development of the nervous system is a highly complex process orchestrated by a multitude of factors, including various immune elements. These immune components play a dual role, not only regulating the immune response but also actively influencing brain development under both physiological and pathological conditions. The brain's immune barrier includes microglia in the brain parenchyma, which act as resident macrophages, astrocytes that support neuronal function and contribute to the inflammatory response, as well as circulating immune cells that reside at the brain's borders, including the choroid plexus, meninges, and perivascular spaces. Cytokines-soluble signaling molecules released by immune cells-play a crucial role in mediating communication between immune cells and the developing nervous system. Cytokines regulate processes such as neurogenesis, synaptic pruning, and inflammation, helping to shape the neural environment. Dysregulation of these immune cells, astrocytes, or cytokine signaling can lead to alterations in neurodevelopment, potentially contributing to neurodevelopmental abnormalities. This article reviews the central role of microglia, astrocytes, cytokines, and other immune factors in neurodevelopment, and explores how neuroinflammation can lead to the onset of neurodevelopmental disorders, shedding new light on their pathogenesis.

Altered tear fluid protein expression in persons with mild Alzheimer's disease in proteins involved in oxidative stress, protein synthesis, and energy metabolism

BackgroundTear fluid (TF) is a protein-rich solution that reflects pathophysiological changes in Alzheimer's disease (AD).ObjectiveIn this study, we examined whether TF proteins were differently expressed in persons with mild AD dementia compared to cognitively healthy controls (CO).MethodsWe analyzed data from 53 study participants including 34 CO (mean age, 71 years; Mini-Mental State Examination [MMSE] score, 28.9 ± 1.4), and 19 patients with AD (Clinical Dementia Rating, 0.5-1; mean age, 72 years; MMSE score, 23.8 ± 2.8). All participants underwent cognitive testing, as well as neurological and ophthalmological examinations. TF was collected using Schirmer strips, and TF protein content was evaluated using mass spectrometry-based proteomics and label-free quantification.ResultsWe found that 16 proteins exhibited significantly upregulated expression in the AD group compared to the CO group (p ≤ 0.05). These proteins were NP1L4, BBOX1, CYTC, RNAS4, PCD, RNT2, AL1A3, SYSC, TPIS, CLH1, PGAM1, EIF3L, 5NTC, HNRNPA2B1, PYGL, and ERO1α. No proteins were significantly downregulated in the AD group compared to the CO group.ConclusionsOur results support the hypothesis that TF is a potential source of biomarkers for AD. Part of those proteins with altered expression have previously linked to increased oxidative stress, changed protein synthesis, and disturbed regulation of energy metabolism related to AD or neurodegenerative disease. The present results indicate the value of continued investigation of TF proteins in AD.

Cathepsin B promotes optic nerve axonal regeneration

This study explored the role of cathepsin B (CTSB) in optic nerve regeneration. Sprague-Dawley rats were utilized for optic nerve crush and long-range crush injury model. Gene and protein expression changes were analyzed via reverse transcription quantitative polymerase chain reaction and western blot. Primary cortical neurons and BV2 cells were cultured to assess CTSB's effects on neuronal outgrowth and microglial activity. Local CTSB administration degraded chondroitin sulfate proteoglycans (CSPGs), promoting axonal growth in-vivo. In-vitro, CTSB neutralized CSPG-mediated inhibition of neuronal growth. Quantitative proteomics revealed elevated microglial marker proteins in the regenerative environment. Activation of signal transducer and activator of transcription 3 (STAT3) and signal transducer and activator of transcription 6 (STAT6) pathways in BV2 cells increased CTSB secretion. These findings suggest that postinjury regenerative microenvironment reconstruction is associated with upregulated CTSB, which degrades CSPGs to facilitate axonal growth. Microglia-derived CTSB, regulated by STAT3/STAT6 signaling, may play a key role in this process. Modulating CTSB expression could thus be a therapeutic strategy to enhance optic nerve regeneration by modifying the injury microenvironment.

Expanding the neuroimmune research toolkit with in vivo brain organoid technologies

Human pluripotent stem cell-derived microglia-like cells (MLCs) and brain organoid systems have revolutionized the study of neuroimmune interactions, providing new opportunities to model human-specific brain development and disease. Over the past decade, advances in protocol design have improved the fidelity, reproducibility and scalability of MLC and brain organoid generation. Co-culturing of MLCs and brain organoids have enabled direct investigations of human microglial interactions in vitro, although opportunities remain to improve microglial maturation and long-term survival. To address these limitations, innovative xenotransplantation approaches have introduced MLCs, organoids or neuroimmune organoids into the rodent brain, providing a vascularized environment that supports prolonged development and potential behavioral readouts. These expanding in vitro and in vivo toolkits offer complementary strategies to study neuroimmune interactions in health and disease. In this Perspective, we discuss the strengths, limitations and synergies of these models, highlighting important considerations for their future applications.

Autophagy and Its Association with Macrophages in Clonal Hematopoiesis Leading to Atherosclerosis

Atherosclerosis, a chronic inflammatory disease characterized by lipid accumulation and immune cell infiltration, is linked to plaque formation and cardiovascular events. While traditionally associated with lipid metabolism and endothelial dysfunction, recent research highlights the roles of autophagy and clonal hematopoiesis (CH) in its pathogenesis. Autophagy, a cellular process crucial for degrading damaged components, regulates macrophage homeostasis and inflammation, both of which are pivotal in atherosclerosis. In macrophages, autophagy influences lipid metabolism, cytokine regulation, and oxidative stress, helping to prevent plaque instability. Defective autophagy exacerbates inflammation, impairs cholesterol efflux, and accelerates disease progression. Additionally, autophagic processes in endothelial cells and smooth muscle cells further contribute to atherosclerotic pathology. Recent studies also emphasize the interplay between autophagy and CH, wherein somatic mutations in genes like TET2, JAK2, and DNMT3A drive immune cell expansion and enhance inflammatory responses in atherosclerotic plaques. These mutations modify macrophage function, intensifying the inflammatory environment and accelerating atherosclerosis. Chaperone-mediated autophagy (CMA), a selective form of autophagy, also plays a critical role in regulating macrophage inflammation by degrading pro-inflammatory cytokines and oxidized low-density lipoprotein (ox-LDL). Impaired CMA activity leads to the accumulation of these substrates, activating the NLRP3 inflammasome and worsening inflammation. Preclinical studies suggest that pharmacologically activating CMA may mitigate atherosclerosis progression. In animal models, reduced CMA activity accelerates plaque instability and increases inflammation. This review highlights the importance of autophagic regulation in macrophages, focusing on its role in inflammation, plaque formation, and the contributions of CH. Building upon current advances, we propose a hypothesis in which autophagy, programmed cell death, and clonal hematopoiesis form a critical intrinsic axis that modulates the fundamental functions of macrophages, playing a complex role in the development of atherosclerosis. Understanding these mechanisms offers potential therapeutic strategies targeting autophagy and inflammation to reduce the burden of atherosclerotic cardiovascular disease.

Adverse Outcome Pathway-Based Strategies to Mitigate Ag2Se Quantum Dot-Induced Neurotoxicity

Silver selenide quantum dots (Ag2Se QDs) show great advantages in tumor imaging due to their excellent optical performance and good biocompatibility. However, the ultrasmall particle size of Ag2Se QDs allows them to cross the blood-brain barrier, thus potentially affecting the central nervous system. Therefore, risk assessment and response strategies for Ag2Se QDs are important. The adverse outcome pathway (AOP) framework makes it possible to develop risk management strategies based on toxicity mechanisms. In this study, using the AOP framework, we constructed causal mechanism relationship diagrams at different biological levels of Ag2Se QD neurotoxicity. In this framework, excess mitochondrial reactive oxygen species (mtROS) triggered Nod-like receptor protein 3 (NLRP3) inflammasome activation in microglia was molecular initiation event (MIE). Proinflammatory mediator secretion and microglia activation were key events (KEs) at the cellular level. Neuroinflammation and neuronal damage were KEs at the organ/tissue level. Altered hippocampal physiology was the adverse outcome (AO) at the individual level. Based on the established AOP framework, further studies confirmed that mtROS-activated nuclear-factor-E2-related factor 2 (Nrf2)/PTEN-induced kinase 1 (PINK1)- mitophagy contributed to weaken the MIE. Molecular docking-assisted molecular biology experiments demonstrated that quercetin (Qu) enhanced this process. This article emphasizes the importance of the AOP in the risk management of nanomaterials. Furthermore, this paper guides the use of natural small-molecule drugs as a strategy to mitigate nanomaterial-induced neurotoxicity.

Programmable production of bioactive extracellular vesicles in vivo to treat myocardial infarction

Current myocardial infarction (MI) treatment strategies remain challenged in suboptimal pharmacokinetics and potential adverse effects. Here we present a bioelectronic interface capable of producing on-demand abundant bioactive extracellular vesicles (EVs) near the MI area for in-situ localized treatment. The technology, termed electroactive patch for wirelessly and controllable EV generation (ePOWER), leverages wireless bioelectronic patch to stimulate embedded electrosensitive macrophages, actively modulating the biosynthesis of EVs and enabling EV production with high programmability to be delivered directly to the MI area. ~2400% more bioactive EVs were produced per cell under our ePOWER system. When surgically implanted, we demonstrate the therapeutic potential of in-situ EV production system to alleviate MI symptoms and improve cardiac function. This programmable ePOWER technology enables in-situ production of therapeutically rich EVs, thus reducing the need for exogenous cell expansion platforms and dedicated delivery, holding promise as a therapeutic all-in-one platform to treat various diseases.

Impact of Microglia-Derived Extracellular Vesicles on Resident Central Nervous System Cell Populations After Acute Brain Injury Under Various External Stimuli Conditions

Acute brain injuries (ABI) caused by various emergencies can lead to structural and functional damage to brain tissue. Common causes include traumatic brain injury, cerebral hemorrhage, ischemic stroke, and heat stroke. Globally, ABI represent a significant portion of neurosurgical cases. Previous studies have emphasized the significant therapeutic potential of stem cell-derived extracellular vesicles (EVs). Recent research indicates that EVs extracted from resident cells in the central nervous system (CNS) also show therapeutic potential following brain injury. Microglia, as innate immune cells of the CNS, respond to changes in the internal environment by altering their phenotype and secreting EVs that impact various CNS cells, including neurons, astrocytes, oligodendrocytes, endothelial cells, neural stem cells (NSCs), and microglia themselves. Notably, under different external stimuli, microglia can either promote neuronal survival, angiogenesis, and myelin regeneration while reducing glial scarring and inflammation, or they can exert opposite effects. This review summarizes and evaluates the current research findings on how microglia-derived EVs influence various CNS cells after ABI under different external stimuli. It analyzes the interaction mechanisms between EVs and resident CNS cells and discusses potential future research directions and clinical applications.

Microglial NOX2 as a therapeutic target in traumatic brain injury: Mechanisms, consequences, and potential for neuroprotection

Traumatic brain injury (TBI) is a leading cause of long-term disability worldwide, with secondary injury mechanisms, including neuroinflammation and oxidative stress, driving much of its chronic pathology. While NADPH oxidase 2 (NOX2)-mediated reactive oxygen species (ROS) production is a recognized factor in TBI, the specific role of microglial NOX2 in perpetuating oxidative and inflammatory damage remains underexplored. Addressing this gap is critical, as current therapeutic approaches primarily target acute symptoms and fail to interrupt the persistent neuroinflammation that contributes to progressive neurodegeneration. Besides NOX, other ROS-generating enzymes, such as CYP1B1, COX2, and XO, also play crucial roles in triggering oxidative stress and neuroinflammatory conditions in TBI. However, this review highlights the pathophysiological role of microglial NOX2 in TBI, focusing on its activation following injury and its impact on ROS generation, neuroinflammatory signaling, and neuronal loss. These insights reveal NOX2 as a critical driver of secondary injury, linked to worsened outcomes, particularly in aged individuals where NOX2 activation is more pronounced. In addition, this review evaluates emerging therapeutic approaches targeting NOX2, such as GSK2795039 and other selective NOX2 inhibitors, which show potential in reducing ROS levels, limiting neuroinflammation, and preserving neurological functions. By highlighting the specific role of NOX2 in microglial ROS production and secondary neurodegeneration, this study advocates for NOX2 inhibition as a promising strategy to improve TBI outcomes by addressing the unmet need for therapies targeting long-term inflammation and neuroprotection. Our review highlights the potential of NOX2-targeted interventions to disrupt the cycle of oxidative stress and inflammation, ultimately offering a pathway to mitigate the chronic impact of TBI.

Lipopolysaccharides from Porphyromonas gingivalis indirectly induce neuronal GSK3β-dependent synaptic defects and cause cognitive decline in a low-amyloid-β-concentration environment in Alzheimer's disease

BackgroundLipopolysaccharides from Porphyromonas gingivalis (P.gLPS) are involved in the pathology of Alzheimer's disease (AD). However, the effect of P.gLPS on synaptic defects remains unclear.ObjectiveIn this study, we tested our hypothesis that P.gLPS induces synaptic defects in a low-amyloid-beta (Aβ)-concentration environment.MethodsMG6 microglia or N2a neurons was treated with P.gLPS (0.1 μg/mL), soluble Aβ42 (0.1 μM) or AL (combined P.gLPS and soluble Aβ42 at 0.1 μM).ResultsIn cultured MG6 microglia, increased the mRNA expression of TNF-α, IL-1β and IL-6 and the TNF-α release in parallel with increased NF-κB activation. In cultured N2a neurons, treatment with Aβ42, P.gLPS, and AL did not affect the mRNA expression of synapsin1 (SYN1) or post-synaptic density protein-95 (PSD-95). However, the treatment with conditioned medium from AL-exposed MG6 microglia (AL-MCM) significantly reduced the mRNA and protein expression of SYN1, PSD-95, and nuclear translocation of repressor element-1 silencing transcription factor (REST) but significantly increased the mRNA expression of TNF receptor type I (at 48 h) and glycogen synthase kinase (GSK)3β (at 24 h). TWS119 pretreatment (5 μM), a GSK3β specific inhibitor, significantly reversed the AL-MCM-induced reduction in the mRNA expression of SYN1 and PSD-95 and nuclear translocation of REST in cultured N2a neurons. In APPNL-F/NL-F mice, the immunofluorescence intensity of SYN1 and PSD-95 in cortical neurons was positively correlated with the index of the memory test but negatively correlated with that of TNF-α-positive microglia.ConclusionsThese observations demonstrate that P.gLPS induces neuronal GSK3β-dependent synaptic defects in a low-Aβ concentration environment via microglial activation.

Glial Cells in Spinal Muscular Atrophy: Speculations on Non-Cell-Autonomous Mechanisms and Therapeutic Implications

Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by homozygous deletions or mutations in the SMN1 gene, leading to progressive motor neuron degeneration. While SMA has been classically viewed as a motor neuron-autonomous disease, increasing evidence indicates a significant role of glial cells-astrocytes, microglia, oligodendrocytes, and Schwann cells-in the disease pathophysiology. Astrocytic dysfunction contributes to motor neuron vulnerability through impaired calcium homeostasis, disrupted synaptic integrity, and neurotrophic factor deficits. Microglia, through reactive gliosis and complement-mediated synaptic stripping, exacerbate neurodegeneration and neuroinflammation. Oligodendrocytes exhibit impaired differentiation and metabolic support, while Schwann cells display abnormalities in myelination, extracellular matrix composition, and neuromuscular junction maintenance, further compromising motor function. Dysregulation of pathways such as NF-κB, Notch, and JAK/STAT, alongside the upregulation of complement proteins and microRNAs, reinforces the non-cell-autonomous nature of SMA. Despite the advances in SMN-restorative therapies, they do not fully mitigate glial dysfunction. Targeting glial pathology, including modulation of reactive astrogliosis, microglial polarization, and myelination deficits, represents a critical avenue for therapeutic intervention. This review comprehensively examines the multifaceted roles of glial cells in SMA and highlights emerging glia-targeted strategies to enhance treatment efficacy and improve patient outcomes.

Crosstalk between neuroinflammation and ferroptosis: Implications for Parkinson's disease progression

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the degeneration of dopaminergic neurons and the aggregation of α-synuclein. Neuroinflammation is triggered by the activation of microglia and astrocytes, which release pro-inflammatory factors that exacerbate neuronal damage. This inflammatory state also disrupts iron homeostasis, leading to the occurrence of ferroptosis. Ferroptosis is characterized by lipid peroxidation of cell membranes and iron overload. Abnormal accumulation of iron in the brain increases oxidative stress and lipid peroxidation, further aggravating neuroinflammation and damage to dopaminergic neurons. Natural products have garnered attention for their antioxidant, anti-inflammatory, and neuroprotective properties, with many plant extracts showing promising therapeutic potential in PD research. This study further investigates the potential therapeutic roles of various natural products in regulating neuroinflammation and ferroptosis. The results suggest that natural products have significant therapeutic potential in modulating the interaction between neuroinflammation and ferroptosis, making them potential treatments for PD. Future research should further validate the safety and efficacy of these natural compounds in clinical applications to develop novel therapeutic strategies for PD.

Pyroptosis; igniting neuropsychiatric disorders from mild depression to aging-related neurodegeneration

Neuropsychiatric disorders significantly impact global health and socioeconomic well-being, highlighting the urgent need for effective treatments. Chronic inflammation, often driven by the innate immune system, is a key feature of many neuropsychiatric conditions. NOD-like receptors (NLRs), which are intracellular sensors, detect danger signals and trigger inflammation. Among these, NLR protein (NLRP) inflammasomes play a crucial role by releasing pro-inflammatory cytokines and inducing a particular cell death process known as pyroptosis. Pyroptosis is defined as a proinflammatory form of programmed cell death executed by cysteine-aspartic proteases, also known as caspases. Currently, the role of pyroptotic flux has emerged as a critical factor in innate immunity and the pathogenesis of multiple diseases. Emerging evidence suggests that the induction of pyroptosis, primarily due to NLRP inflammasome activation, is involved in the pathophysiology of various neuropsychiatric disorders, including depression, stress-related issues, schizophrenia, autism spectrum disorders, and neurodegenerative diseases. Within this framework, the current review explores the complex relationship between pyroptosis and neuropsychiatric diseases, aiming to identify potential therapeutic targets for these challenging conditions.

Single-nucleus transcriptome profiling provides insights into the pathophysiology of adhesive arachnoiditis

Adhesive arachnoiditis (AA) is a rare form of chronic degenerative pathology associated with persistent inflammation in the arachnoid matter of the spinal cord. Despite the existing knowledge, the detailed pathological mechanisms underlying AA are not fully understood. This study aimed to elucidate through comprehensive single nuclei RNA sequencing (snRNA-seq) to delineate the transcriptomic landscape of AA. From six arachnoid membrane samples, a total of 52,886 cells met the quality control standards for analysis. The main cell populations identified with specific gene markers were as follows: fibroblasts, glial cells, microglial cells, endothelial cells, mural cells, plasma cells, and T cells. Downstream analysis of fibroblasts, glial cells, and microglial cells was performed. Notably, fibroblast subsets 1 and 3 demonstrated a strong association with AA. Among them, subcluster 3 demonstrated elevated expression of genes COL1A1, COL3A1, and FN1, indicative of enhanced Wnt/β-catenin and extracellular matrix (ECM) synthesis pathways. Subcluster 3 was predicted to progressively transform into subcluster 1. In subcluster 1, there was a significant upregulation of genes such as BMP and ALPL, signaling enhanced activation of calcification-related pathways. This was highly relevant to end-stage arachnoid ossification formation. After being activated, microglial cells transformed into inflammatory disease-associated microglial cells and continued to express high levels of chemokines CCL2, CCL4, IL-1β, and other inflammatory factors NAMPT, INPP5D and NLRP3. This might be the main reason why AA recurrence is frequently observed in patients. These insights enhance our understanding of the pathological progression of AA and may contribute to the identification of novel therapeutic targets.

Vagus nerve stimulation (VNS) preventing postoperative cognitive dysfunction (POCD): two potential mechanisms in cognitive function

Postoperative cognitive dysfunction (POCD) impacts a significant number of patients annually, frequently impairing their cognitive abilities and resulting in unfavorable clinical outcomes. Aimed at addressing cognitive impairment, vagus nerve stimulation (VNS) is a therapeutic approach, which was used in many mental disordered diseases, through the modulation of vagus nerve activity. In POCD model, the enhancement of cognition function provided by VNS was shown, demonstrating VNS effect on cognition in POCD. In the present study, we primarily concentrates on elucidating the role of the VNS improving the cognitive function in POCD, via two potential mechanisms: the inflammatory microenvironment and epigenetics. This study provided a theoretical support for the feasibility that VNS can be a potential method to enhance cognition function in POCD.

The Use of Identified Hypoxia-related Genes to Generate Models for Predicting the Prognosis of Cerebral Ischemia‒reperfusion Injury and Developing Treatment Strategies

Cerebral ischemia‒reperfusion injury (CIRI) is a type of secondary brain damage caused by reperfusion after ischemic stroke due to vascular obstruction. In this study, a CIRI diagnostic model was established by identifying hypoxia-related differentially expressed genes (HRDEGs) in patients with CIRI. The ischemia‒reperfusion injury (IRI)-related datasets were downloaded from the Gene Expression Omnibus (GEO) database ( http://www.ncbi.nlm.nih.gov/geo ), and hypoxia-related genes in the Gene Cards database were identified. After the datasets were combined, hypoxia-related differentially expressed genes (HRDEGs) expressed in CIRI patients were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of the HRDEGs were performed using online tools. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were performed with the combined gene dataset. CIRI diagnostic models based on HRDEGs were constructed via least absolute shrinkage and selection operator (LASSO) regression analysis and a support vector machine (SVM) algorithm. The efficacy of the 9 identified hub genes for CIRI diagnosis was evaluated via mRNA‒microRNA (miRNA) interaction, mRNA-RNA-binding protein (RBP) network interaction, immune cell infiltration, and receiver operating characteristic (ROC) curve analyses. We then performed logistic regression analysis and constructed logistic regression models based on the expression of the 9 HRDEGs. We next established a nomogram and calibrated the prediction data. Finally, the clinical utility of the constructed logistic regression model was evaluated via decision curve analysis (DCA). This study revealed 9 critical genes with high diagnostic value, offering new insights into the diagnosis and selection of therapeutic targets for patients with CIRI. : Not applicable.

Lactate accumulation from HIF-1α-mediated PMN-MDSC glycolysis restricts brain injury after acute hypoxia in neonates

Fetal intrauterine distress (FD) during delivery can cause fetal intrauterine hypoxia, posing significant risks to the fetus, mother, and newborns. While studies highlight the role of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in neonatal diseases and tumor hypoxia, their specific involvement in newborns experiencing fetal distress during delivery (FDNB) is not well understood. Here, we found elevated PMN-MDSC activation, increased glycolysis, enhanced lactate production, and upregulated HIF-1α expression in the blood of FDNB neonates compared to healthy newborns (NNB). Importantly, PMN-MDSC levels were inversely correlated with neuron-specific enolase (NSE), a marker for neurological injury. In neonatal mice subjected to acute hypoxia, a 48-h exposure led to a shift from exacerbation to amelioration of brain damage when compared with a 24-h period. This change was associated with a reduction in microglial activation, a decrease in the expression of inflammatory factors within the microglia, alongside increased peripheral PMN-MDSC activation. Depleting PMN-MDSCs led to heightened microglial activation and aggravated brain injury. Mechanistically, enhanced activation of PMN-MDSCs promotes HIF-1α accumulation while enhancing glycolysis and lactate release, thereby mitigating neonatal brain injury. Notably, lactate supplementation in hypoxic mice rescued brain damage caused by insufficient PMN-MDSC activation due to HIF-1α deficiency. Our study clarifies the role of lactate in peripheral PMN-MDSCs after acute hypoxia and its effects on microglial activation and subsequent brain injury.

MeCP2 Modulates Depression-Like Behaviors Comorbid to Chronic Pain by Regulating Adult Hippocampal Neurogenesis

AIMS

Although previous studies have revealed the association between chronic pain-induced depression and defective adult hippocampal neurogenesis (AHN), the underlying molecular mechanism remains elusive. This study aims to examine the association between AHN and depression-like behaviors, and to reveal the underlying mechanisms.

METHODS

The chronic neuropathic pain model was established using mice with the spared nerve injury (SNI) surgery. The depression-like behaviors were evaluated by using the sucrose preference test (SPT), the tail suspension test (TST), the forced swimming test (FST), and the open field test (OFT). The expression of Methyl-CpG-binding protein 2 (MeCP2) was modulated by injecting the adeno-associated virus (AAV) with the DIO system into the ventral DG of the Nes-CreERT2 mice. The miRNAs in hippocampal neural stem cells (NSCs) of mice with chronic pain were analyzed via miRNA sequencing.

RESULTS

We found that MeCP2, an epigenetic factor that plays a key role in the development of neurons, was significantly down-regulated in NSCs in the dentate gyrus (DG) of the hippocampus in adult mice with chronic pain and comorbid depression, suggesting a role of MeCP2 in the regulation of depression-like behavior induced by chronic neuropathic pain. MeCP2 expression levels in hippocampal NSCs were closely related to AHN and chronic pain comorbid depression, and miR-199b-3p specifically targeted and inhibited MeCP2 expression by directly interacting with its 3'-UTR sequence. Furthermore, we demonstrated that the increased level of miR-199b-3p in NSCs after the occurrence of chronic pain was responsible for AHN inhibition and comorbid depression.

CONCLUSION

Chronic neuropathic pain may result in an increased level of miR-199b-3p in hippocampal NSCs, which in turn targeted the Mecp2 gene and inhibited its transcription. Inhibited MeCP2 expression in NSCs contributes to AHN inhibition and depression-like behaviors.

Microglial Responses to Alzheimer's Disease Pathology: Insights From "Omics" Studies

Human genetics studies lent firm evidence that microglia are key to Alzheimer's disease (AD) pathogenesis over a decade ago following the identification of AD-associated genes that are expressed in a microglia-specific manner. However, while alterations in microglial morphology and gene expression are observed in human postmortem brain tissue, the mechanisms by which microglia drive and contribute to AD pathology remain ill-defined. Numerous mouse models have been developed to facilitate the disambiguation of the biological mechanisms underlying AD, incorporating amyloidosis, phosphorylated tau, or both. Over time, the use of multiple technologies including bulk tissue and single cell transcriptomics, epigenomics, spatial transcriptomics, proteomics, lipidomics, and metabolomics have shed light on the heterogeneity of microglial phenotypes and molecular patterns altered in AD mouse models. Each of these 'omics technologies provide unique information and biological insight. Here, we review the literature on the approaches and findings of these methods and provide a synthesis of the knowledge generated by applying these technologies to mouse models of AD.

Advancing Mental Health Research Through Strategic Integration of Transdiagnostic Dimensions and Genomics

Genome-wide studies are yielding a growing catalog of common and rare variants that confer risk for psychopathology. However, despite representing unprecedented progress, emerging data also indicate that the full promise of psychiatric genetics-including understanding pathophysiology and improving personalized care-will not be fully realized by targeting traditional dichotomous diagnostic categories. The current article provides reflections on themes that emerged from a 2021 National Institute of Mental Health-sponsored conference convened to address strategies for the evolving field of psychiatric genetics. As anticipated by the National Institute of Mental Health's Research Domain Criteria framework, multilevel investigations of dimensional and transdiagnostic phenotypes, particularly when integrated with biobanks and big data, will be critical to advancing knowledge. The path forward will also require more diverse representation in source studies. Additionally, progress will be catalyzed by a range of converging approaches, including capitalizing on computational methods, pursuing biological insights, working within a developmental framework, and engaging health care systems and patient communities.

Physiological change of striatum and ventral midbrain's glia cell in response to different exercise modalities

Exercise not only regulates neurotransmitters and synapse formation but also enhances the function of multiple brain regions, beyond cortical activation. Prolonged aerobic or resistance exercise modality has been widely applied to reveal the beneficial effects on the brain, but few studies have investigated the direct effects of different exercise modalities and variations in exercise intensity on the neuroinflammatory response in the brain and overall health. Therefore, in this study, we investigated changes in brain cells and the immune environment of the brain according to exercise modalities. This study was conducted to confirm whether different exercise modalities affect the location and function of dopaminergic neurons, which are responsible for regulating voluntary movement, before utilizing animal models of disease. The results showed that high-intensity interval exercise (HIE) increased the activity of A2-reactive astrocytes in the striatum (STR), which is directly involved in movement control, resulting in neuroprotective effects. Both HIE and combined exercises (CE) increased the expression of dopamine transporter (DAT) in the STR without damaging dopamine neurons in the ventral midbrain (VM). This means that exercise training can help improve and maintain exercise capacity. In conclusion, specific exercise modalities or intensity of exercise may contribute to preventing neurodegenerative diseases such as Parkinson's disease or enhancing therapeutic effects when combined with medication for patients with neurodegenerative diseases.

Evaluation of [18F]JNJ-CSF1R-1 as a Positron Emission Tomography Ligand Targeting Colony-Stimulating Factor 1 Receptor

PURPOSE

Colony-stimulating factor 1 receptor (CSF1R) signaling plays a pivotal role in neuroinflammation, driving microglia proliferation and activation. CSF1R is considered a hallmark of inflammation in many neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). Our study aims to evaluate the potential value of 5-cyano-N-(4-(4-(2-([18F]fluoro)ethyl)piperazin-1-yl)-2-(piperidin-1-yl)phenyl)furan-2-carboxamide ([18F]JNJ-CSF1R-1) as a positron emission tomography (PET) ligand targeting CSF1R in preclinical models of neuroinflammation.

PROCEDURES

A cell-based MSD assay was used to measure the IC50 of 5-cyano-N-(4-(4-(2-(fluoro)ethyl)piperazin-1-yl)-2-(piperidin-1-yl)phenyl)furan-2-carboxamide (JNJ-CSF1R-1). JNJ-CSF1R-1 was radiolabeled with fluorine-18. PET imaging was used to evaluate brain uptake, and target engagement of [18F]JNJ-CSF1R-1 in two neuroinflammation mouse models, including systemic lipopolysaccharide (LPS) and AppSAA knock in (KI). CSF1R protein levels in brain tissue were determined by western blot and ELISA assays. [18F]JNJ-CSF1R-1 brain uptake was also measured in a non-human primate (NHP) PET study.

RESULTS

JNJ-CSF1R-1 is a 12 nM (IC50) inhibitor of CSF1R. ​[18F]JNJ-CSF1R-1 demonstrated significantly higher brain uptake in both LPS and AD mouse models as measured by the area under the time activity curves (AUC) compared to control animals. In the AppSAA KI model, CSF1R levels increased near amyloid plaques as detected by IHC. ​[18F]JNJ-CSF1R-1 PET imaging signal showed a good correlation with CSF1R expression levels measured by western blot and ELISA. In an NHP study, ​[18F]JNJ-CSF1R-1 readily entered the brain and demonstrated reversible kinetics.

CONCLUSION

​[18F]JNJ-CSF1R-1 is a potent and promising CSF1R PET tracer with translational potential for measuring microglia-based neuroinflammatory processes and for tracking the impact of anti-inflammatory therapies.

Age-Related Differences in Lipopolysaccharide-Induced Delirium-like Behavior Implicate the Distinct Microglial Composition in the Hippocampus

As the global population ages, the mechanisms underlying age-related susceptibility to delirium have attracted attention. Given the central role of microglia in the pathogenesis of inflammation-related delirium, we investigated the temporal dynamics of neurobehavioral changes and microglial responses, following lipopolysaccharide (LPS, 200 μg/kg) administration in young and old male C57BL/6 mice. Although a similar illness trajectory across 48 h post-treatment (HPT) was observed in both age groups, old-LPS mice exhibited worsened delirium-like behavior. At 48 HPT, in old but not young mice, significantly decreased hippocampal neuronal activity coincided with microglial overactivation. Widespread hippocampal microglial activation was present at 3 HPT but subsided by 12 HPT in young but not old mice, indicating a generally retarded but prolonged microglial response to LPS challenge in old mice. However, for both age groups, at 3 HPT, p16INK4a-negative microglia (with low abundance in the aged brain) exhibited comparable morphological activation, which was not observed for p16INK4a-positive microglia (highly abundant in the aged brain). These results suggest that age-related susceptibility to LPS-induced delirium-like behavior accompanied by different patterns of microglial response might implicate microglial composition shifts and that optimizing microglial composition represents a promising approach to reduce vulnerability to inflammatory challenge.

Microglial Mechanisms and Therapeutic Potential in Brain Injury Post-Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a particularly common public health problem with a high mortality and disability rate and no effective treatments to enhance clinical prognosis. The increased aging population, improved vascular prevention, and augmented use of antithrombotic agents have collectively contributed to the rise in ICH incidence over the past few decades. The exploration and understanding of mechanisms and intervention strategies has great practical significance for expanding treatments and improving prognosis of ICH. Microglia, as resident macrophages of central nervous system, are responsible for the first immune defense post-ICH. After ICH, M1 microglia is firstly activated by primary injury and thrombin; subsequently, reactive microglia can further amplify the immune response and exert secondary injury (eg, oxidative stress, neuronal damage, and brain edema). The pro-inflammatory phenotype transmits to M2 microglia within 7 days post-ICH, which plays a key role in erythrophagocytosis and limiting the inflammatory secondary injury. Microglial M2 polarization has significant implications for improving prognosis, this process can be mediated through crosstalk with other cells, metabolic changes, and microbiota interaction. Clarifying the effect, timing, and potential downstream effects of multiple mechanisms that synergistically trigger anti-inflammatory responses may be necessary for clinical translation. Analyses of such intricate interaction between microglia cells and brain injury/repair mechanisms will contribute to our understanding of the critical microglial responses to microenvironment and facilitating the discovery of appropriate intervention strategies. Here, we present a comprehensive overview of the latest evidences on microglial dynamics following ICH, their role in driving primary/secondary injury mechanisms as well as neurorepair/plasticity, and possible treatment strategies targeting microglia.

The roles and therapeutic potential of exosomal non-coding RNAs in microglia-mediated intercellular communication

Exosomes, which are small extracellular vesicles (sEVs), serve as versatile regulators of intercellular communication in the progression of various diseases, including neurological disorders. Among the diverse array of cargo they carry, non-coding RNAs (ncRNAs) play key regulatory roles in various pathophysiological processes. Exosomal ncRNAs derived from distinct cells modulate their reciprocal crosstalk locally or remotely, thereby mediating neurological diseases. Nevertheless, the emerging role of exosomal ncRNAsin microglia-mediated phenotypes remains largely unexplored. This review aims to summarise the biological functions of exosomal ncRNAs and the molecular mechanisms that underlie their impact on microglia-mediated intercellular communication, modulating neuroinflammation and synaptic functions within the landscape of neurological disorders. Furthermore, this review comprehensively described the potential applications of exosomal ncRNAs as diagnostic and prognostic biomarkers, as well as innovative therapeutic targets for the treatment of neurological diseases.

Genes, Cognition, and Their Interplay in Methamphetamine Use Disorder

Methamphetamine use disorder is a pressing global health issue, often accompanied by significant cognitive deficits that impair daily functioning and quality of life and complicate treatment. Emerging evidence highlights the potential role of genetic factors in methamphetamine use disorder, particularly in association with cognitive function. This review examines the key genetic and cognitive dimensions and their interplay in methamphetamine use disorder. There is converging evidence from several studies that genetic polymorphisms in BDNF, FAAH, SLC18A1, and SLC18A2 are associated with protection against or susceptibility to the disorder. In addition, people with methamphetamine use disorder consistently displayed impairments in cognitive flexibility and inhibitory control compared with people without the disorder. These cognitive domains were associated with reactivity to methamphetamine cues that were positively correlated with total years of methamphetamine use history. Emerging research also suggests that inhibitory control is negatively correlated with lower blood FAAH mRNA levels, while cognitive flexibility positively correlates with higher blood SLC18A2 mRNA levels, highlighting how genetic and cognitive dimensions interact in methamphetamine use disorder. We also include some future directions, emphasizing potential personalized therapeutic strategies that integrate genetic and cognitive insights. By drawing attention to the interplay between genes and cognition, we hope to advance our understanding of methamphetamine use disorder and inform the development of targeted interventions.

CXCR2 modulates chronic pain comorbid depression in mice by regulating adult neurogenesis in the ventral dentate gyrus

Research shows that chronic pain may induce depression-like behaviors through impairing adult hippocampal neurogenesis (AHN) in the ventral dentate gyrus (DG), whereas restoration of AHN may effectively alleviate depression. The C-X-C motif chemokine receptor 2 (CXCR2) is a chemokine receptor involved in various neural activities of the hippocampus including AHN. In this study we investigated the role of CXCR2 of neural stem cells (NSCs) in the ventral DG in regulating both AHN and depression-like behaviors of mice with chronic neuropathic pain. Chronic neuropathic pain was induced in mice by the spared nerve injury (SNI) surgery; mechanical allodynia and depression-like behaviors were monitored, then mouse DG was collected for analysis. We observed that chronic neuropathic pain significantly decreased the number of immature neurons in the ventral DG by inhibiting the neuronal differentiation of NSCs; specific overexpression of CXCR2 in NSCs by injecting the adeno-associated virus (AAV) into the DG restored adult neurogenesis accompanied by alleviated depression-like behaviors in SNI mice. In contrast, the knockdown of CXCR2 in hippocampal NSCs of naive mice was sufficient to inhibit adult neurogenesis, inducing depression-like behaviors. Moreover, we found that the Wnt3a/β-catenin pathway was downregulated in the ventral DG of SNI mice, which was restored after CXCR2 overexpression or infusing a CXCR2 agonist CXCL1 into the ventral DG. We conclude that CXCR2 expressed in hippocampal NSCs is crucial for regulating adult neurogenesis and chronic pain-induced depression-like behavior, thus representing a new target for the treatment of chronic pain comorbid depression.

Effects of Combined Shinbaro and Celecoxib in a Complete Freund's Adjuvant-Induced Inflammatory Pain Mouse Model

Purpose

Persistent inflammation resulting from injury, infection, or arthritis contributes to both peripheral and central sensitization. Various combinations of natural extracts have been explored to minimize the side effects associated with conventional medications. Shinbaro, which has traditionally been used in Eastern medicine to treat inflammatory conditions, was chosen due to its known anti-inflammatory properties. However, previous studies have not yet investigated the combined administration of celecoxib and Shinbaro for their anti-inflammatory and analgesic effects. In this study, we examined the anti-inflammatory and analgesic effects of combining celecoxib with Shinbaro in a complete Freund's adjuvant (CFA)-induced inflammatory pain model.

Methods

We randomly assigned 66 mice to 6 groups (n = 11 per group) and administered intraplantar injections of 100 μL CFA or saline into their right hind paw, followed by oral administration of Shinbaro (100 mg/kg), celecoxib (15 or 30 mg/kg), or both 30 minutes later. Behavioral assessments were conducted blindly at baseline and on days 1, 3, and 7 post-injection. The right hind paw and spinal cord were harvested 3 days post-injection to examine the molecular mechanisms, including macrophage infiltration in the right hind paw, as well as glial cell activation and inflammatory cytokine levels in the spinal cord. Statistical analysis was performed using Tukey's post-hoc test.

Results

The combination of Shinbaro (100 mg/kg) and celecoxib (15 mg/kg) synergistically reduced mechanical hyperalgesia and paw edema by preventing the conversion of monocytes to macrophages and inhibiting macrophage infiltration. Moreover, it decreased the expression of pro-inflammatory cytokines and mediators in the spinal cord by inhibiting spinal microglial activation.

Conclusion

The combination of Shinbaro and celecoxib demonstrates significant anti-inflammatory and analgesic effects, suggesting its potential for managing inflammatory pain with fewer side effects than conventional therapies.

Microglia aggregates define distinct immune and neurodegenerative niches in Alzheimer's disease hippocampus

In Alzheimer's disease (AD), microglia form distinct cellular aggregates that play critical roles in disease progression, including Aβ plaque-associated microglia (PaM) and the newly identified coffin-like microglia (CoM). PaM are closely associated with amyloid-β (Aβ) plaques, while CoM are enriched in the pyramidal layer of the CA2/CA1 hippocampal subfields, where they frequently engulf neurons and associate with tau-positive tangles and phosphorylated α-synuclein. To elucidate the role of these microglial subtypes, we employed high-content neuropathology, integrating Deep Spatial Profiling (DSP), multiplex chromogenic immunohistochemistry and confocal microscopy, to comprehensively map and characterise their morphological and molecular signatures, as well as their neuropathological and astrocytic microenvironments, in AD and control post-mortem samples. PaM and PaM-associated astrocytes exhibited signatures related to complement system pathways, ErbB signalling, and metabolic and neurodegenerative processes. In contrast, CoM displayed markers associated with protein degradation and immune signalling pathways, including STING, TGF-β, and NF-κB. While no direct association between CD8 + T cells and either microglial type was observed, CD163 + perivascular macrophages were frequently incorporated into PaM. These findings provide novel insights into the heterogeneity of microglial responses, in particular their distinct interactions with astrocytes and infiltrating immune cells, and shed light on specific neurodegenerative hotspots and their implications for hippocampal deterioration in AD.

Immune Modulation in Alzheimer's Disease: From Pathogenesis to Immunotherapy

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the leading cause of dementia, affecting a significant proportion of the elderly population. AD is characterized by cognitive decline and functional impairments due to pathological hallmarks like amyloid β-peptide (Aβ) plaques and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau. Microglial activation, chronic neuroinflammation, and disruptions in neuronal communication further exacerbate the disease. Emerging research suggests that immune modulation could play a key role in AD treatment given the significant involvement of neuroinflammatory processes. This review focuses on recent advancements in immunotherapy strategies aimed at modulating immune responses in AD, with a specific emphasis on microglial behavior, amyloid clearance, and tau pathology. By exploring these immunotherapeutic approaches, we aim to provide insights into their potential to alter disease progression and improve patient outcomes, contributing to the evolving landscape of AD treatment.

Impact of neuroinflammation on brain glutamate and dopamine signalling in schizophrenia: an update

Schizophrenia is one of the most severe and chronic psychiatric disorders. Over the years, numerous treatment options have been introduced for schizophrenia. Although they are relatively successful in managing the positive symptoms of schizophrenia, most of the current treatments have a negligible effect on the negative and cognitive symptoms. Thus, none of them could prevent the relapse of psychotic episodes. Among the numerous hypotheses explaining the development and progression of schizophrenia, the cytokine hypothesis explains the role of inflammatory markers as a significant culprit in the development of schizophrenia. Elevated cytokines are reported in animal models and schizophrenic patients. The cytokine hypothesis is based on how increased inflammatory markers can cause changes in the dopaminergic, glutamate, and tryptophan metabolism pathways, like that observed in schizophrenic patients. Reasons, such as autoimmune disease, maternal immune activation, infection, etc., can pave the way for the development of schizophrenia and are associated with the negative, positive and cognitive symptoms of schizophrenia. Thus, there is a need to focus on the significance of anti-inflammatory drugs against these symptoms. The development of new treatment strategies in the management of schizophrenia can provide better therapeutic outcomes in terms of the severity of symptoms and treatment of drug-resistant schizophrenia. This review attempts to explain the association between elevated inflammatory markers and various neurotransmitters, and the possible use of medications like nonsteroidal anti-inflammatory drugs, monoclonal antibodies, statins, and estrogens as adjuvant therapy. Over the years, these hypotheses have been the basis for drug discovery for the treatment of schizophrenia.

Photobiomodulation of gut microbiota with low-level laser therapy: a light for treating neuroinflammation

The gut microbiota is known to interact with various organs in the body, including the central nervous system, through the gut-brain axis. Intestinal dysbiosis can lead to increased peripheral inflammation and, consequently, affect the brain, resulting in neuroinflammation. Photobiomodulation (PBM) has demonstrated positive regulatory effects on the imbalance of certain body functions, including pain, inflammation, immunity, wound healing, and gut microbiota dysbiosis. Therefore, PBM at the intestinal level could help improve intestinal dysbiosis and reestablish cerebral homeostasis. In this context, this study aimed to conduct a narrative review of the literature on the effects of PBM at the intestinal level on intestinal dysbiosis and neuroinflammation. Overall, the findings highlight that PBM modulates the gut microbiota, suggesting it could serve as a therapy for neurological conditions affecting the gut-brain axis. Future research should focus on further elucidating the molecular mechanisms underlying this therapy.

Multimodal transcriptomics reveal neurogenic aging trajectories and age-related regional inflammation in the dentate gyrus

The mammalian dentate gyrus (DG) is involved in certain forms of learning and memory, and DG dysfunction has been implicated in age-related diseases. Although neurogenic potential is maintained throughout life in the DG as neural stem cells (NSCs) continue to generate new neurons, neurogenesis decreases with advancing age, with implications for age-related cognitive decline and disease. In this study, we used single-cell RNA sequencing to characterize transcriptomic signatures of neurogenic cells and their surrounding DG niche, identifying molecular changes associated with neurogenic aging from the activation of quiescent NSCs to the maturation of fate-committed progeny. By integrating spatial transcriptomics data, we identified the regional invasion of inflammatory cells into the hippocampus with age and show here that early-onset neuroinflammation decreases neurogenic activity. Our data reveal the lifelong molecular dynamics of NSCs and their surrounding neurogenic DG niche with age and provide a powerful resource to understand age-related molecular alterations in the aging hippocampus.

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.

Synthesis, preclinical evaluation and pilot clinical study of a P2Y12 receptor targeting radiotracer [18F]QTFT for imaging brain disorders by visualizing anti-inflammatory microglia

As the brain's resident immune cells, microglia perform crucial functions such as phagocytosis, neuronal network maintenance, and injury restoration by adopting various phenotypes. Dynamic imaging of these phenotypes is essential for accessing brain diseases and therapeutic responses. Although numerous probes are available for imaging pro-inflammatory microglia, no PET tracers have been developed specifically to visualize anti-inflammatory microglia. In this study, we present an 18F-labeled PET tracer (QTFT) that targets the P2Y12, a receptor highly expressed on anti-inflammatory microglia. [18F]QTFT exhibited high binding affinity to the P2Y12 (14.43 nmol/L) and superior blood-brain barrier permeability compared to other candidates. Micro-PET imaging in IL-4-induced neuroinflammation models showed higher [18F]QTFT uptake in lesions compared to the contralateral normal brain tissues. Importantly, this specific uptake could be blocked by QTFT or a P2Y12 antagonist. Furthermore, [18F]QTFT visualized brain lesions in mouse models of epilepsy, glioma, and aging by targeting the aberrantly expressed P2Y12 in anti-inflammatory microglia. In a pilot clinical study, [18F]QTFT successfully located epileptic foci, showing enhanced radioactive signals in a patient with epilepsy. Collectively, these studies suggest that [18F]QTFT could serve as a valuable diagnostic tool for imaging various brain disorders by targeting P2Y12 overexpressed in anti-inflammatory microglia.

Microglia programmed cell death in neurodegenerative diseases and CNS injury

Programmed cell death (PCD) has emerged as a critical regulatory mechanism in the initiation and progression of various pathological conditions. PCD in microglia, including necroptosis, pyroptosis, apoptosis, ferroptosis, and autophagy, occurs in a variety of central nervous system (CNS) diseases. Dysregulation of microglia can lead to excessive tissue damage or neuronal death in CNS injury. Various injury stimuli trigger aberrant activation of the PCD pathway of microglia, which then further leads to inflammatory cascades that exacerbates CNS pathology in a vicious cycle. Therefore, targeting PCD in microglia is considered an important avenue for the treatment of various neurodegenerative diseases and CNS injury. In this review, we summarize the major and recent findings focusing on the mechanisms of PCD in microglia modulating functions in neurodegenerative diseases and CNS injury and provide a systematic overview of the current inhibitors targeting various PCD pathways, which may provide important therapeutic targets that merit further investigation.

Role of NLRP3 Inflammasome in Chronic Pain and Alzheimer's Disease-A Review

The coexistence of Alzheimer's disease (AD) and chronic pain (CP) in the elderly population has been extensively documented, and a growing body of evidence supports the potential interconnections between these two conditions. This comprehensive review explores the mechanisms by which CP may contribute to the development and progression of AD, with a particular focus on neuroinflammatory pathways and the role of microglia, as well as the activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome. The review proposes that prolonged pain processing in critical brain regions can dysregulate the activity of the NLRP3 inflammasome within microglia, leading to the overproduction of pro-inflammatory cytokines and excessive oxidative stress in these regions. This aberrant microglial response also results in localized neuroinflammation in brain areas crucial for cognitive function. Additionally, CP as a persistent physiological and psychological stressor may be associated with hypothalamic-pituitary-adrenal (HPA) axis dysfunction, systemic inflammation, disruption of the blood-brain barrier (BBB), and neuroinflammation. These pathophysiological changes can cause morphological and functional impairments in brain regions responsible for cognition, memory, and neurotransmitter production, potentially contributing to the development and progression of CP-associated AD. Resultant neuroinflammation can further promote amyloid-beta (Aβ) plaque deposition, a hallmark of AD pathology. Potential therapeutic interventions targeting these neuroinflammatory pathways, particularly through the regulation of microglial NLRP3 activation, hold promise for improving outcomes in individuals with comorbid CP and AD. However, further research is required to fully elucidate the complex interplay between these conditions and develop effective treatment strategies.

Intermittent Fasting Ameliorates β-Amyloid Deposition and Cognitive Impairment Accompanied by Decreased Lipid Droplet Aggregation Within Microglia in an Alzheimer's Disease Model

SCOPE

Alzheimer's disease (AD) is the most prevalent form of dementia, lack of effective therapeutic interventions. In this study, we investigate the impact of intermittent fasting (IF), an alternative strategy of calorie restriction, on cognitive functions and AD-like pathology in a transgenic mouse model of AD.

METHODS AND RESULTS

APP/PS1 mice at 6 months were randomly allocated to two dietary groups: one receiving ad libitum (AL) feeding and the other undergoing IF for 1 month. Y maze, Barnes maze, western blotting, and immunofluorescence were employed. Behavioral assessments revealed that the APP/PS1-IF group demonstrated notable improvements in cognitive function compared to the AL group. Further analysis showed that microglia in the APP/PS1-IF mice exhibited enhanced phagocytic activity, characterized by prominent enlargement of soma and reduced complexity of their processes. Importantly, IF significantly decreased the accumulation of lipid droplets (LDs) within microglia. These microglia with less LDs may contribute to enhanced β-amyloid (Aβ) phagocytosis, thereby ameliorating Aβ deposition in the brains of APP/PS1-IF mice.

CONCLUSION

Our findings demonstrate that IF ameliorates amyloid deposition and cognitive deficits in the AD model mice, which is associated with the reduction of LDs within microglia, providing support for the use of the dietary intervention against AD pathology.

Inflammatory signalling during the perinatal period: Implications for short- and long-term disease risk

During pregnancy and the postpartum, there are dynamic fluctuations in steroid and peptide hormone levels as well as inflammatory signalling. These changes are required for a healthy pregnancy and can persist well beyond the postpartum. Many of the same hormone and inflammatory signalling changes observed during the perinatal period also play a role in symptoms related to autoimmune disorders, psychiatric disorders, and perhaps neurodegenerative disease later in life. In this review, we outline hormonal and immunological shifts linked to pregnancy and the postpartum and discuss the possible role of these shifts in increasing psychiatric, neurodegenerative disease risk and autoimmune symptoms during and following pregnancy. Furthermore, we discuss how key variables such as the number of births (parity) and sex of the fetus can influence inflammatory signalling, and possibly future disease risk, but are not often studied. We conclude by discussing the importance of studying female experiences such as pregnancy and parenting on physiology and disease.