Search Results (385)

Microglia, the brain’s resident innate immune cells, play a fundamental role in maintaining neural homeostasis and mediating responses to injury or infection. Upon activation, microglia undergo morphological and functional changes, including phenotypic switching between pro- and anti-inflammatory types and the release of different inflammatory mediators. These processes contribute to neuroprotection and the pathogenesis of various central nervous system (CNS) disorders. Mast cells, although sparsely located in the brain, exert a significant influence on neuroinflammation through their interactions with microglia. Through degranulation and secretion of different mediators, mast cells disrupt the blood–brain barrier and modulate microglial responses, including alteration of microglial phenotypes. Notably, mast cell-derived factors, such as histamine, interleukins, and tryptase, activate microglia through various pathways including protease-activated receptor 2 and purinergic receptors. These interactions amplify inflammatory cascades via various signaling pathways. Previous studies have revealed an exceedingly complex crosstalk between mast cells and microglia suggesting a bidirectional regulation of CNS immunity, implicating their cooperation in both neurodegenerative progression and repair mechanisms. Here, we review some of the diverse communication pathways involved in this complex interplay. Understanding this crosstalk may offer novel insights into the cellular dynamics of neuroinflammation and highlight potential therapeutic targets for a variety of CNS disorders. Full article

Although exercise is known to exert anti-inflammatory effects in neurodegenerative diseases, its specific impact and underlying mechanisms in Parkinson’s disease (PD) remain poorly understood. This study explores the effects of exercise on microglia-mediated neuroinflammation and apoptosis in a PD model, focusing on the role of irisin signaling in mediating these effects. Using a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model, we found that a 10-week treadmill exercise regimen significantly enhanced motor function, reduced dopaminergic neuron loss, attenuated neuronal apoptosis, and alleviated neuroinflammation. Exercise also shifted microglia from a pro-inflammatory to an anti-inflammatory phenotype. Notably, levels of irisin, phosphorylated AMP-activated protein kinase (p-AMPK), and sirtuin 1 (Sirt1), which were decreased in the PD brain, were significantly increased following exercise. These beneficial effects were abolished by blocking the irisin receptor with cyclic arginine–glycine–aspartic acid–tyrosine–lysine (cycloRGDyk). Our results indicate that exercise promotes neuroprotection in PD by modulating microglial activation and the AMPK/Sirt1 pathway through irisin signaling, offering new insights into exercise-based therapeutic approaches for PD. Full article

Neuroinflammation, driven by activated microglia, contributes to the progression of neurodegenerative diseases. Extracellular vesicles mediate intercellular communication and influence immune responses. Chrysin, a natural flavone found in fruits and propolis, has demonstrated anti-inflammatory effects. This study explored the immunomodulatory potential of chrysin-loaded EVs (EVs-Chry) derived from BV2 microglial cells. BV2 cells were treated with chrysin for 24 h to assess cytotoxicity and proliferation. EVs were isolated from treated and untreated cells, characterized by nanoparticle tracking analysis, and applied to naïve BV2 cells prior to LPS stimulation. Effects on cell morphology, migration, cytokine expression (IL-1β, IL-6), inflammasome activity (caspase-1), and apoptosis-related protein Bcl-xL were investigated. Our results show that EVs-Chry significantly reduced LPS-induced cell proliferation, restored resting microglial morphology, and reduced migratory capacity. Furthermore, co-treatment with EVs-Chry and LPS reduced pro-inflammatory cytokines such as IL-1β, IL-6, and caspase-1 expression while enhancing anti-apoptotic Bcl-xL levels, indicating a shift toward an anti-inflammatory, neuroprotective micro-glial phenotype. Together, our results demonstrated that EVs-Chry have neuroprotective effects on LPS-induced microglial activation and modulate microglial responses to inflammatory stimuli, attenuating pro-inflammatory signaling and promoting cellular homeostasis. These findings support the therapeutic potential of EVs-Chry in the context of neuroinflammatory and neurodegenerative disorders. Full article

In familial Alzheimer’s disease (FAD), presenilin 1 (PSEN1) E280A cholinergic-like neurons (ChLNs) induce aberrant secretion of extracellular amyloid beta (eAβ). How PSEN1 E280A ChLNs-eAβ affects microglial activity is still unknown. We obtained induced microglia-like cells (iMG) from human peripheral blood cells (hPBCs) in a 15-day differentiation process to investigate the effect of bolus addition of Aβ42, PSEN1 E280A cholinergic-like neuron (ChLN)-derived culture supernatants, and PSEN1 E280A ChLNs on wild type (WT) iMG, PSEN1 E280A iMG, and sporadic Alzheimer’s disease (SAD) iMG. We found that WT iMG cells, when challenged with non-cellular (e.g., lipopolysaccharide, LPS) or cellular (e.g., Aβ42, PSEN1 E280A ChLN-derived culture supernatants) microenvironments, closely resemble primary human microglia in terms of morphology (resembling an “amoeboid-like phenotype”), expression of surface markers (Ionized calcium-binding adapter molecule 1, IBA-1; transmembrane protein 119, TMEM119), phagocytic ability (high pHrodo™ Red E. coli BioParticles™ phagocytic activity), immune metabolism (i.e., high generation of reactive oxygen species, ROS), increase in mitochondrial membrane potential (ΔΨm), response to ATP-induced transient intracellular Ca²⁺ influx, cell polarization (cluster of differentiation 68 (CD68)/CD206 ratio: M1 phenotype), cell migration activity according to the scratch wound assay, and especially in their inflammatory response (secretion of cytokine interleukin-6, IL-6; Tumor necrosis factor alpha, TNF-α). We also found that PSEN1 E280A and SAD iMG are physiologically unresponsive to ATP-induced Ca²⁺ influx, have reduced phagocytic activity, and diminished expression of Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) protein, but when co-cultured with PSEN1 E280A ChLNs, iMG shows an increase in pro-inflammatory phenotype (M1) and secretes high levels of cytokines IL-6 and TNF-α. As a result, PSEN1 E280A and SAD iMG induce apoptosis in PSEN1 E280A ChLNs as evidenced by abnormal phosphorylation of protein TAU at residue T205 and cleaved caspase 3 (CC3). Taken together, these results suggest that PSEN1 E280A ChLNs initiate a vicious cycle between damaged neurons and M1 phenotype microglia, resulting in excessive ChLN death. Our findings provide a suitable platform for the exploration of novel therapeutic approaches for the fight against FAD. Full article

Amyotrophic lateral sclerosis (ALS) remains a progressive neurodegenerative disease, lacking effective causal therapies. The Wobbler mouse model harboring a spontaneous autosomal recessive mutation in the vacuolar protein sorting associated protein (Vps54), has emerged as a valuable model for investigating ALS pathophysiology and potential treatments. This model exhibits cellular and phenotypic parallels to human ALS, including protein aggregation, microglia and astrocyte activation, as well as characteristic disease progression at distinct stages. Exploring the underlying pathomechanisms and identifying therapeutic targets requires a comprehensive analysis of gene and protein expression. In this study, we examined the expression of three well-established housekeeping genes and proteins—calnexin, ß-actin, and ßIII-tubulin—in the cervical spinal cord of the Wobbler model. These candidates were selected based on their demonstrated stability across various systems like animal models or cell culture. Calnexin, an integral protein of the endoplasmic reticulum, ß-actin, a structural component of the cytoskeleton, and ß-tubulin III, a component of microtubules, were quantitatively assessed using quantitative reverse transcription-polymerase chain reaction (RT-PCR) for gene expression and Western blotting for protein expression. Our results revealed no significant differences in the expression of CANX, ACTB, and TUBB3 between spinal cords of wild-type and Wobbler mice at the symptomatic stage (p40) at both the gene and protein levels. These findings suggest that the pathophysiological alterations induced by the Wobbler mutation do not significantly affect the expression of these crucial housekeeping genes and proteins at p40. Overall, this study provides a basis for further investigations using the Wobbler mouse model, while highlighting the potential use of calnexin, ß-actin, and ßIII-tubulin as reliable reference genes and proteins in future research to aid in the discovery for effective therapeutic interventions. Full article

Amyotrophic lateral sclerosis (ALS) is characterized by upper and lower motor neuron failure and poor prognosis. This study performed a meta-analysis of gene expression datasets that compared bulk-processed post-mortem spinal cord from ALS and control (CTL) patients. The analysis included 569 samples (454 ALS, 115 CTL) from 348 individuals (262 ALS, 86 CTL). Patterns of differential expression bias, related to mRNA abundance, gene length and GC content, were discernable from individual studies but attenuated by meta-analysis. A total of 213 differentially expressed genes (DEGs) were identified (144 ALS-increased, 69 ALS-decreased). ALS-increased DEGs were most highly expressed by microglia and associated with MHC class II, immune response and leukocyte activation. ALS-decreased DEGs were abundantly expressed by mature oligodendrocytes (e.g., the MOL5 phenotype) and associated with myelin production, plasma membrane and sterol metabolism. Comparison to spatial transcriptomics data showed that DEGs were prominently expressed in white matter, with increased DEG expression strongest in the ventral/lateral white matter. These results highlight white matter as the spinal cord region most strongly associated with the shifts in mRNA abundance observed in bulk-processed tissues. These shifts can be explained by attrition of mature oligodendrocytes and an ALS-emergent microglia phenotype that is partly shared among neurodegenerative conditions. Full article

Neuroinflammation is a key process in Alzheimer’s disease (AD). We aimed to examine the development and evaluation of a comprehensive in vitro model that captures the complex interplay between neurons and immune cell types. Retinoic acid-differentiated SH-SY5Y neuroblastoma cells exposed to LPS-conditioned media (CM) from RAW264.7 macrophages, BV2 microglia, and HL60 promyelocytic cells differentiated into neutrophil- or monocyte-like phenotypes were analyzed. The effects of CM containing inflammatory factors on neuronal viability and function were systematically evaluated. Neuronal oxidative stress, mitochondrial function, autophagy and protein aggregates were analyzed. The involvement of insulin resistance was studied by assaying glucose uptake and determining its IC₅₀ values for cell viability improvement and GSK3β phosphorylation. After short-term exposure (3 h), most inflammatory CMs induced peroxide production in neurons, with the strongest effect observed in media from DMSO- or RA-differentiated HL60 cells. Mitochondrial membrane potential was markedly reduced by LPS-stimulated BV2 and HL60-derived CMs. Prolonged exposure (72 h) revealed partial normalization of oxidative stress and mitochondrial membrane potential. Glucose uptake was significantly impaired in cells treated with LPS-activated RAW264.7, BV2, and DMSO-differentiated HL60 cell media, while insulin partially rescued this effect, except for the CM of BV2 cells. Notably, insulin IC₅₀ increased dramatically under LPS-treated BV2 cells induced inflammation (35 vs. 198 pM), confirming the development of insulin resistance. Immune cell-specific inflammation causes distinct effects on neuronal oxidative stress, mitochondrial function, protein aggregation, insulin signaling and viability. LPS-activated BV2-derived CM best recapitulates AD-related pathology, offering a relevant in vitro model for further studies. Full article

Background/Objectives: To study the efficacy and pharmacological mechanism of the dual-target liposome complex AD808 in the treatment of Alzheimer’s disease. Methods: Using APP/PS1 mouse models, the therapeutic efficacy and pharmacological mechanism of AD808 on Alzheimer’s disease were studied through water maze tests, brain tissue staining, immunofluorescence, and ELISA for inflammatory and neurotrophic factors. Results: AD808 exhibited significant pharmacodynamic effects in improving behavioral and cognitive abilities (70% reduction in escape latency) and repairing damaged nerve cells (90% reduction in Aβ plaque) in Alzheimer’s disease mice. The efficacy of the liposome complex AD808 was significantly better than that of ST707 or gh625-Zn₇MT3 alone. AD808 significantly reduced brain inflammation (57.3% and 61.5% reductions in TNF-α and IL-1β, respectively) in AD (Alzheimer’s disease) mouse models and promoted the upregulation of neurotrophic factors and nerve growth factors (142.8% increase in BDNF, 275.9% in GDNF, and 111.3% in NGF-1) in brain homogenates. By activating the PI3K/AKT signaling pathway in brain microglia, AD808 upregulated TREM2 protein expression and removed Aβ amyloid plaques in the brain. Additionally, it promoted the transition of microglia from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, regulated the M1/M2 balance, released anti-inflammatory and neurotrophic factors, reduced chronic inflammation, and enhanced neurological repair. Based on these results, the potential pharmacological mechanism of AD808 against Alzheimer’s disease was proposed. Conclusions: As a dual-target liposome complex, AD808 has shown promising therapeutic potential in the treatment of Alzheimer’s disease, providing a new strategy for innovative drug development. Full article

Apolipoprotein E (APOE) alleles play distinct roles in the pathogenesis of Alzheimer’s disease (AD), with APOEε4 being the strongest genetic risk factor for late-onset AD, while APOEε2 appears protective. Despite extensive research, the precise mechanisms by which APOE alleles contribute to AD pathology remain incompletely understood. Recent advances in multi-omics technologies and single-cell analyses have revealed that APOE alleles shape microglial phenotypes, thereby affecting amyloid clearance, inflammatory responses, tau pathology, and lipid metabolism. In this review, we provide a detailed overview of how APOE alleles differentially regulate microglial activation, inflammatory signaling, phagocytic activity, and lipid metabolism in the context of AD, with a particular focus on the APOEε4-mediated disruption of microglial homeostasis via pathways such as TREM2 signaling, NF-κB/NLRP3 activation, ACSL1 upregulation, and HIF-1α induction. These insights not only advance our understanding of APOE allele-specific contributions to AD pathology, but also highlight novel therapeutic strategies targeting the APOE–microglia axis. Full article

Glutamate is an excitatory neurotransmitter in the central nervous system (CNS) that mediates synaptic transmission. However, glutamate homeostasis among neural cells is broken in cerebral ischemia. Excessive glutamate triggers N-methyl-d-aspartate receptors (NMDARs) in postsynaptic neurons, leading to intracellular calcium (Ca²⁺) overload and excitoneurotoxicity. At this moment, L-lactate may affect NMDARs and play a protective role in cerebral ischemia. This work proposes that L-lactate regulates glutamate signaling among neural cells. But, dysregulation of L-lactate in glutamate signaling cascades contributes to glutamate excitotoxicity in cerebral ischemia. In detail, L-lactate regulates the glutamine(Gln)-glutamate cycle between astrocytes and presynaptic neurons, which triggers the astroglial L-lactate-sensitive receptor (LLR)-cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway, coordinating astroglial glutamate uptake and neuronal glutamate transmission. L-lactate mediates glutamate signaling and synaptic transmission among neural cells. In addition, L-lactate promotes the function of mitochondrial calcium uniporter complex (MCUC), which quickly depletes intracellular Ca²⁺ in postsynaptic neurons. In addition, L-lactate can promote the conversion of microglia from the pro-inflammatory (M1) to anti-inflammatory (M2) phenotype. Therefore, regulation of L-lactate in glutamate signaling in the CNS might become a preventive target for cerebral ischemia. Full article

Microglia, the resident immune cells of the central nervous system (CNS), play essential roles in maintaining brain homeostasis. While transient activation is protective, chronic microglial reactivity contributes to neuroinflammatory damage and neurodegeneration. The mitochondrial mechanisms underlying this shift remain poorly understood. Here, we investigated whether lipopolysaccharide (LPS) induces coordinated mitochondrial and metabolic alterations in BV-2 microglial cells. LPS stimulation (100 ng/mL, 24 h) induced a reactive phenotype, with increased Iba1 (+82%), F4/80 (+132%), and Cd68 (+44%), alongside elevated hydrogen peroxide (~6-fold) and nitrite (~45-fold). Cytotoxicity increased by 40% (LDH assay), and cell viability dropped to ~80% of the control (MTT). Extracellular lactate increased, indicating glycolytic reprogramming. However, LPS-primed cells showed greater ATP depletion under antimycin A challenge, reflecting impaired metabolic flexibility. Hoechst staining revealed a ~4-fold increase in pyknotic nuclei, indicating apoptosis. Mitochondrial dysfunction was confirmed by a 30–40% reduction in membrane potential (TMRE, JC-1), a ~30% loss of Tomm20, and changes in dynamics: phospho-Drp1 increased (+23%), while Mfn1/2 decreased (33%). Despite a ~70% rise in Lamp2 signal, Tomm20–Lamp2 colocalization decreased, suggesting impaired mitophagy. High-resolution respirometry revealed decreased basal (−22%), ATP-linked (24%), and spare respiratory capacity (41%), with increased non-mitochondrial oxygen consumption. These findings demonstrate that LPS induces mitochondrial dysfunction, loss of metabolic adaptability, and increased apoptotic susceptibility in microglia. Mitochondrial quality control and energy flexibility emerge as relevant targets to better understand and potentially modulate microglial responses in neuroinflammatory and neurodegenerative conditions. Full article

Adult neurogenesis in the hippocampal dentate gyrus (DG) is not only essential for learning and pattern separation, but it is also involved in emotional regulation. This process is vulnerable to local and peripheral inflammation, which is partly mediated by microglia in the DG. As Crohn’s disease (CD) is associated with neuropsychiatric comorbidity, including depression and cognitive impairment, a reduction in adult hippocampal neurogenesis by chronic gut-derived inflammation has been hypothesized. Here, we present the first study that examined the influence of chronic ileocolitis on microglia in the DG and on adult hippocampal neurogenesis in a transgenic mouse model of CD, which is generated by a constitutive knockout of caspase 8 in intestinal epithelial cells (IECs, Casp8^ΔIEC mice). Structural and transcriptional analyses revealed that microglial cell proliferation and density in the DG as well as the expression of genes associated with their homeostasis and activation in the forebrain were maintained in 14- and 24-week-old Casp8^ΔIEC mice compared to Casp8^fl controls. Furthermore, different stages of adult hippocampal neurogenesis, including progenitor cell proliferation, maturation, and apoptosis of newly generated cells, were predominantly unaffected by chronic ileocolitis, except a potential minor phenotypic shift in maturating cells in 24-week-old mice. Together, we demonstrate largely preserved adult hippocampal neurogenesis, lacking signs of local inflammatory microglial activation despite chronic inflammation of the gut. Full article

Background: Chronic ischemic stroke presents a significant challenge in neurology, with limited therapeutic options available for long-term recovery. During cerebral infarction, anti-inflammatory phenotype microglia/macrophages produce anti-inflammatory cytokines and neurotrophic factors that facilitate the process of brain repair. However, obtaining sufficient anti-inflammatory microglia/macrophages from the human central nervous system is challenging. Bone marrow-derived inducible microglia-like cells (BM-iMGs) with an anti-inflammatory microglial phenotype were explored to induce neuroprotective properties. Here, we transplanted BM-iMGs into the brain of middle cerebral artery occlusion (MCAO) model male mice to explore their potential for treating chronic ischemic stroke. Methods: Bone marrow-derived mononuclear cells (BM-MNCs) were isolated from green fluorescent protein mice and incubated with granulocyte–macrophage colony-stimulating factor (GM-CSF) and IL-4 to induce BM-iMGs with an anti-inflammatory phenotype. BM-iMGs were transplanted into the brains of mice on day 14 after MCAO, and behavioral tests, histology, cerebral blood flow, and gene expression were evaluated. Results: An intracranial injection of BM-iMGs promoted neurobehavioral recovery, reduced neuronal cell loss, suppressed neuroinflammatory astrocytic and microglial responses in the brain, and increased cortical surface cerebral blood flow in MCAO mice. Furthermore, neuroprotective genes were upregulated, whereas proinflammatory genes were downregulated. Conclusions: The intracranial injection of BM-iMG cells shows significant potential as a novel therapy for chronic ischemic stroke. Full article

T lymphocytes infiltrate the CNS in response to murine cytomegalovirus (MCMV) infection and form a pool of long-lived brain tissue-resident memory T-cells (bT_RMs), which display markers of residency (i.e., CD103, CD69, CD49a). However, the functional role of these bT_RMs is still unknown. By 30 days postinfection, a latent viral brain infection was established, as indicated by absence of viral transcripts (IE1, E1, and gB) produced during productive infection. Following intracerebroventricular injection of either depleting α-CD8 Ab (clone YTS169.4) or α-CD103-sap (clone IT50) into the brain, 90–95% T-cell depletion was achieved. Using luciferase-expressing mice, we observed recommenced imaging signals indicative of de novo MCMV IE promoter activity in depleted animals. Surprisingly, using an explant assay, we efficiently recovered reactivatable, infectious virus from untreated, latent animals, but not from those depleted of bT_RMs (viral recovery in explants was reduced from 100% to 50% by day 21). We identified Lgals3 (galectin 3), Gpnmb (glycoprotein nonmetastatic melanoma protein B) and Hmox1 (heme oxygenase 1) as genes that were most upregulated in bT_RM-depleted groups. When bT_RMs were depleted, there was transient expression of viral IE genes which resulted in antiviral microglia with a phagocytic, disease-associated (DAM) or neurodegenerative (MGnD) phenotype. These data provide new insights into the role of bT_RMs in controlling both CNS reactivation and driving microglial phenotypes. Full article

Microglial cells, the resident immune cells of the central nervous system (CNS), are essential for maintaining CNS homeostasis. Dysregulation of microglial function is implicated in the pathogenesis of various neurodegenerative diseases. Vasoactive intestinal polypeptide receptors 1 and 2 (VPAC1 and VPAC2) are G-protein-coupled receptors (GPCRs) expressed by microglia, with their primary ligands being pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP). However, the specific roles of VPAC-type receptors in microglial regulation remain poorly understood. In this study, we generated VPAC1^+/− and VPAC2^+/− BV2 microglial cell lines using CRISPR-Cas9 gene editing and conducted a series of biological and molecular assays to elucidate the functions of these receptors. Our findings demonstrated that both mutant cell lines exhibited a polarized phenotype and increased migratory activity. VPAC1^+/− cells showed enhanced survivability and baseline activation of the unfolded protein response (UPR), a protective mechanism triggered by endoplasmic reticulum (ER) stress, whereas this response appeared impaired in VPAC2^+/− cells. In contrast, under lipopolysaccharide (LPS)-induced inflammatory conditions, UPR activation was impaired in VPAC1^+/− cells but restored in VPAC2^+/− cells, resulting in improved survival of VPAC2^+/− cells, whereas VPAC1^+/− cells exhibited reduced resilience. Overall, our findings suggest that VPAC1 and VPAC2 receptors play distinct yet complementary roles in BV2 microglia. VPAC2 is critical for regulating survival, ER stress responses, and polarization under basal conditions, while VPAC1 is essential for adaptive responses to inflammatory stimuli such as LPS. These insights advance our understanding of microglial receptor signaling and may inform therapeutic strategies targeting microglial dysfunction in neurodegenerative diseases. Full article