Search Results (60)

The blood–brain barrier (BBB) is a highly intricate neurovascular structure that plays a crucial role in maintaining neural homeostasis by selectively allowing certain molecules to enter the central nervous system (CNS). However, in the context of Alzheimer’s Disease (AD), a progressive neurodegenerative disorder characterized by a gradual decline in cognitive function, the BBB’s functionality becomes impaired. This impairment leads to the breakdown of the barrier and disrupts its ability to regulate molecular transport effectively. Consequently, cellular infiltration into the CNS occurs, along with aberrant signaling and clearance of molecules, ultimately contributing to neurological deficits. One of the key factors implicated in the failure of amyloid-beta (Aβ) transport, a hallmark of AD, is the decreased expression of low-density lipoprotein receptor-related protein 1 (LRP1). LRP1 plays a crucial role in facilitating the transport of Aβ across the BBB. Additionally, the increased levels of the receptor for advanced glycation end products (RAGE) further contribute to the deregulation of the BBB in AD. These molecular imbalances significantly impact Aβ clearance and contribute to the development and progression of AD. In this review, we aimed to summarize the critical aspects of Aβ transporters in the BBB that become dysfunctional during the pathogenesis of AD. Full article

Alzheimer’s disease (AD) is one of the major causes of dementia and its incidence represents approximately 60–70% of all dementia cases worldwide. Many theories have been proposed to describe the pathological events in AD, including deterioration in cognitive function, accumulation of β-amyloid, and tau protein hyperphosphorylation. Infection as well as various cellular molecules, such as apolipoprotein, micro-RNA, calcium, ghrelin receptor, and probiotics, are associated with the disruption of β-amyloid and tau protein hemostasis. This review gives an overview on the integrative cellular and signaling molecules that could play a complementary role in the dysregulation of β-amyloid and tau proteins. Full article

Gamma-aminobutyric acid (GABA) is an essential neurotransmitter and an important regulator of neuroinflammation and disease. Microglia are important immune cells in the brain that express GABA receptors (GABAR) and respond to both GABA and GABAR agonists, yet the effect of GABA on microglial inflammatory responses is unclear. We hypothesized that GABA and GABAR agonists might modify the activation of a human microglial cell line (HMC3). We further hypothesized that Amanita muscaria extract (AME-1), which contained GABAR agonists (GABA and muscimol), would similarly stimulate HMC3. Ligand-gated GABAR (GABA_AR) and G protein-coupled GABAR (GABABR) subunit expression was analyzed by qRT-PCR, metabolic activity was determined by nicotinamide adenine dinucleotide (NADH)-dependent oxidoreductase assay (XTT), reactive oxygen species (ROS) generation was analyzed by 2′,7′-dichlorodihydrofluorescein diacetate (DCFDA), and interleukin-8 (IL-8) production was analyzed by an enzyme-linked immunosorbent assay (ELISA). HMC3 expressed several neuroreceptors such as subunits of the GABA_A receptor (GABA_AR). HMC3 constitutively produce IL-8 and ROS. Both muscimol and GABA stimulated HMC3 to produce more IL-8 but had no effect on constitutive ROS production. GABA and muscimol altered the morphology and Iba1 localization of HMC3. GABA, but not muscimol, increased HMC3 metabolic activity. Similarly, AME-1 induced HMC3 to produce more IL-8 but not ROS and altered cell morphology and Iba1 localization. GABA induction of IL-8 was blocked by bicuculline, an antagonist of GABA_AR. AME-1-induced production of IL-8 was not blocked by bicuculline, suggesting that AME-1’s effect on HMC3 was independent of GABA_AR. In conclusion, these data show that GABA and GABA agonists stimulate HMC3 to increase their production of IL-8. Mixtures that contain GABA and muscimol, such as AME-1, have similar effects on HMC3 that are independent of GABA_AR. Full article

The plasma membrane glucose transporter (GLUT)-2 is unique among GLUT family proteins in that it also functions as a glucose sensor. GLUT2 imposes sex-dimorphic control of hypothalamic astrocyte glucose storage and catabolism by unknown mechanisms. Mitogen-activated protein kinase (MAPK) signaling cascades operate within stress-sensitive signal transduction pathways. The present study employed an established primary astrocyte culture model and gene knockdown tools to investigate whether one or more of the three primary MAP kinase families are regulated by GLUT2. GLUT2 gene knockdown caused opposing adjustments in total ERK1/2 proteins in glucose-supplied male versus female astrocytes, augmenting or reducing the mean phosphorylated/total protein ratio for 44 and 42 kDa variants in these sexes. Glucose deprivation amplified this ratio for both ERK1/2 variants, albeit by a larger magnitude in males; GLUT2 siRNA exacerbated this stimulatory response in males only. Phosphorylated/total p38 MAPK protein ratios were up-regulated by GLUT2 knockdown in male, but not female astrocytes. Glucose-deprived astrocytes exhibited no change (male) or reduction (female) in this ratio after GLUT2 gene silencing. GLUT2 siRNA increased the phosphorylated/total protein ratio for 54 and 46 kDa SAPK/JNK proteins in each sex when glucose was present. However, glucose withdrawal suppressed (male) or amplified (female) these ratios, while GLUT2 knockdown attenuated these inverse responses. The results show that GLUT2 inhibits ERK1/2, p38, and SAPK/JNK MAPK activity in male astrocytes, but differentially stimulates and inhibits activity of these signaling pathways in female hypothalamic astrocytes. Glucoprivation induces divergent adjustments in astrocyte p38 MAPK and SAPK/JNK activities. The findings demonstrate a stimulatory role for GLUT2 in p38 MAPK activation in glucose-starved female astrocytes, but it can act as either an inhibitor or inducer of SAPK/JNK activation in glucose-deprived male versus female glial cells, respectively. Full article

Neuroimmunomodulation is a promising form of drug-free treatment for neurological diseases ranging from Alzheimer’s disease to depression. The evidence supporting the efficacy of focused ultrasound (FUS) neuroimmunomodulation is encouraging; however, the method has yet to be standardized, and its mechanism remains poorly understood. Methods of FUS neuroimmunomodulation can be categorized into three paradigms based on the parameters used. In the first paradigm, focused ultrasound blood–brain barrier opening (FUS-BBBO) combines FUS with microbubbles (MB) to transiently and safely induce BBB opening. In the second paradigm, focused ultrasound neuromodulation (FUS-N) harnesses the acoustic effects of FUS alone (without MB). In the third paradigm, focused ultrasound with microbubbles without BBBO (FUS + MB) combines MB with FUS below the BBBO pressure threshold—harnessing the mechanical effects of FUS without opening the barrier. Due to the recent evidence of brain macrophage modulation in response to FUS-BBBO, we provide the first direct comparison of brain macrophage modulation between all three paradigms both in the presence and absence of Alzheimer’s disease (AD) pathology. Flow cytometry and single-cell sequencing are employed to identify FUS-BBBO as the FUS paradigm, which maximizes brain macrophage modulation, including an increase in the population of neuroprotective, disease-associated microglia and direct correlation between treatment cavitation dose and brain macrophage phagocytosis. Next, we combine spatial and single-cell transcriptomics with immunohistochemical validation to provide the first characterization of brain macrophage distribution in response to FUS-BBBO. Given their relevance within neurodegeneration and perturbation response, we emphasize the analysis of three brain macrophage populations—disease- and interferon-associated microglia and central-nervous-system-associated macrophages. We find and validate the redistribution of each population with an overall trend toward increased interaction with the brain–cerebrospinal fluid barrier (BCSFB) after FUS-BBBO, an effect that is found to be more pronounced in the presence of disease pathology. This study addresses the prior lack of FUS neuroimmunomodulation paradigm optimization and mechanism characterization, identifying that FUS-BBBO best modulates brain macrophage response via complex redistribution. Full article

A paradigm shift is currently taking place in the etiopathogenesis of neuropsychiatric disorders as immunometabolism is replacing the earlier neurotransmitter model. According to the new concept, cellular bioenergetics drives information processing in the central nervous system; therefore, neuropathology is conceptualized as a direct consequence of impaired metabolism. Along the same lines, endoplasmic reticulum stress and gut barrier dysfunction are emerging as novel targets in schizophrenia and affective disorders, linking immune responses to cellular distress. Furthermore, microglia, the brain’s innate immune cells, acquire energy through oxidative phosphorylation, while in the resting state, and glycolysis upon activation, contributing to lactate accumulation and reduced brain pH. The same metabolic signature characterizes neuropsychiatric disorders as the central nervous system derives adenosine triphosphate from aerobic glycolysis, upregulating lactate and generating an acidic environment. Although known for over three decades, the link between dysmetabolism and neuropathology was poorly defined until the discovery of brain-resident innate lymphoid cells, including natural killer cells, and lactylation of histone and nonhistone proteins. In this perspective article, we examine three anti-inflammatory microglial systems relevant for neuropsychiatry: lactate, oxytocin, and the aryl hydrocarbon receptor. We also discuss potential interventions for restoring microglial homeostasis. Full article

Glioblastoma (GBM) is the most commonly occurring type of primary tumor of the central nervous system (CNS) and is considered the worst type of glioma. Despite the current standard treatment for newly diagnosed GBM, which involves surgery followed by chemotherapy with temozolomide (TMZ) and radiation therapy, the average survival time for patients with GBM is only about 15 months. This is due to GBM’s tendency to recur, its high proliferative rates, its ability to evade apoptosis, and its ability to invade healthy tissue. Therefore, it is crucial to explore new treatment options for GBM. This study investigated the potential anticancer activities of a new series of synthetic chalcones, which are natural compounds found in the biosynthesis of flavonoids in plants. Primary cell culture of glioblastoma (GBM1) from surgical resection was used to evaluate the effects of synthetic chalcones on viability, cell death, reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), cell cycle, and invasion. One chalcone, Q1VA (at concentrations of 10, 50, and 100 μM for 24 h) induced cytotoxicity by increasing apoptosis levels and depolarizing the mitochondrial membrane, as evidenced by a TMRE assay. Further analysis using the molecular fluorescent probe H2DCFDA indicated that the increased levels of reactive oxygen species (ROS) might be linked to altered mitochondrial membrane potential and cell death. Furthermore, viable cells were observed to be delayed in the cell cycle, primarily in the M phase, and the invasion process was reduced. The findings of this study indicate that Q1VA is a potential adjuvant therapeutic agent for GBM due to its significant antitumor effects. If its safety and efficacy can be confirmed in animal models, Q1VA may be considered for clinical trials in humans. However, additional research is required to determine the optimal dosage, treatment schedule, and potential side effects of Q1VA. Full article

Mood and anxiety disorders are heterogeneous psychiatric diagnoses affecting millions. While the disease etiology is complex, various risk factors have been identified, such as stress. Stress is a neuroendocrine physiologic response to a stressor that promotes organism survival through adaptive processes and behavior. The central stress response, which drives behavioral and physiological change, is primarily mediated by activating the hypothalamic–pituitary–adrenal (HPA) axis. In addition to its effects on the HPA axis, stress activates the locus coeruleus (LC), a bilateral brainstem nucleus that projects broadly throughout the central nervous system and releases the catecholamine transmitter norepinephrine (NE). The combined activities of the LC–NE system and HPA axis work synergistically to produce timely adaptive physiological and behavioral responses to stress. While advantageous in the short term, chronic stress exposure can lead to HPA axis and LC dysregulation, which are thought to contribute to the etiology of several neuropsychiatric disease states. Notably, recent studies have also implicated neuroinflammation mediated by microglia as a risk factor in mood and anxiety disorders. Despite their combined association with mood and anxiety disorders, the potential links between stress and inflammation, and possible interactions between their respective signaling cascades, have not been well-explored. This brief review aims to summarize how LC is uniquely positioned to respond to both pro-stress and pro-inflammatory cues, and how their convergence in this site may contribute to the development of mood and anxiety disorders. Full article

We previously reported on the experimental validation of several in silico-predicted glioma biomarkers (e.g., Plexin-B2 (PLXNB2), SLIT3, and Spondin-1 (SPON1)) that were found to be higher in human high-grade gliomas (HGGs). In this study, we validated their therapeutic potential by investigating antibody therapies against these three biomarkers in a preclinical mouse GL261 high-grade glioma model. Efficacies for antibody therapies against these biomarkers were assessed by survival and tumor volumes, biomarker expressions, cell invasion and proliferation, and bioinformatics gene/protein associations. Antibodies against PLXNB2, SLIT3, or SPON1 were effective in significantly reducing tumor volumes and increasing animal survival. With immunohistochemistry (IHC), these biomarkers were highly expressed in human HGGs, as well as in mice tumors. From IHC, CD44v6 was significantly decreased for all three antibody treatments, compared to UT GL261 tumors. Bioinformatics suggested that targeting either PLXNB2 or SPON1 may have a major effect on HGG cell migration and invasion (validated with CD44v6 IHC), whereas targeting SLIT3, in addition to affecting cell invasion, may also affect cell proliferation (not validated with Ki67 IHC). These results indicate that targeting these three biomarkers could add to the therapeutic arsenal against high-grade gliomas and that antibodies against them could be considered for clinical translation. Full article

Spinocerebellar ataxia type 1 (SCA1) is a fatal, dominantly inherited neurodegenerative disease caused by the expansion of CAG repeats in the Ataxin-1 (ATXN1) gene. SCA1 is characterized by the early and prominent pathology of the cerebellar Purkinje cells that results in balance and coordination deficits. We previously demonstrated that cerebellar astrocytes contribute to SCA1 pathogenesis in a biphasic, stage of disease-dependent manner. We found that pro-inflammatory transcriptional regulator nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) signaling in astrocytes has a neuroprotective role during early-stage SCA1. Here, we sought to examine whether further inducing NF-κB activation in astrocytes of SCA1 model mice at an early stage of the disease has therapeutic benefits. To perform this task, we created a novel Slc1a3-CreER^T/IKKβ_CA/ATXN1[82Q] triple transgenic mouse model in which TMX injection at 4 weeks of age results in the expression of constitutively active inhibitor of kB kinase beta (IKKβ_CA), the main activator of NF-κB signaling. As we evaluated SCA1-like phenotypes, we noticed that ATXN1[82Q] mice did not exhibit motor deficits anymore, even at very late stages of the disease. We sequenced the mutant ATXN1 gene and discovered that the CAG repeat number had decreased from 82 to 71. However, despite the loss of motor phenotype, other well-characterized SCA1-changes, including atrophy of Purkinje cell dendrites, hallmarks of cerebellar astrogliosis and microgliosis, and Purkinje cell disease-associated gene expression changes, were still detectable in ATXN1[71Q] mice. We found delayed PC atrophy and calbindin reduction in SCA1 mice expressing IKKβ_CA in astrocytes implicating beneficial effects of increased NF-κB signaling on Purkinje cell pathology. The change in the motor phenotype of SCA1 mice with CAG reduction prevented us from evaluating the neuroprotective potential of IKKβ_CA on motor deficits in these mice. Full article

Astrocytes and microglia play important roles in organizing the structure and function of neuronal networks in the central nervous system (CNS). The dorsal diencephalic connection system (DDCS) is a phylogenetically ancient regulatory system by which the forebrain influences the activity of cholinergic and ascending monoaminergic pathways in the midbrain. The DDCS is probably important in inducing aspects of mental disorders, such as depression and addiction. The habenula is the small but highly complex connecting center of the DDCS in the epithalamus that consists of a medial (MHb) and lateral (LHb) division. MHb and LHb are built differently and connect different brain structures. Studies in animal models and human biomarker research provide good evidence that astroglia and microglia also affect the symptoms of mental disorders (such as depression). The significance of these neuroglia in habenular neurotransmission has not been extensively studied. This review article provides arguments for doing so more thoroughly. Full article

Glioma, specifically gliobastoma, represents the commonest central nervous system malignancy and is notoriously challenging to treat, with only a minimal number of patients surviving beyond a year after diagnosis. The available treatment options include surgical resection, radiotherapy, and chemotherapy, mainly with temozolomide. However, gliomas can be particularly treatment resistant and novel options are currently being researched. One such agent is ONC201, the first member of the imipridone class and a TNF-related apoptosis inducing ligand (TRAIL)-inducing compound, which has shown positive results in the first preliminary clinical reports about its application in glioma patients, while also being safe and well-tolerated. Particular promise has been shown for the H3K27M mutated glioblastomas, with more trials focusing on this patient subset. It is likely that this compound will be added in the treatment algorithms of glioma in the future, although more research is still needed. Full article

Chronic itch (CI) is an unpleasant skin sensation accompanied by an intense scratching desire that lasts 6 weeks or longer. Despite the high prevalence and negative impact on affected individuals and a huge healthcare burden, CI mechanisms are only partially understood, and consequently, treatment of CI remains sub-optimal. The complexity of CI treatment also stems from the comorbid existence of persistent itch with other somatic and psychological disorders. Etiologies of CI are multiple and diverse, although CI is often a result of dermatologically related conditions such as atopic dermatitis and psoriasis. Unfolding the pathophysiology of CI can provide possibilities for better therapy. Itch signaling is complex and neurons and non-neuronal cells play a role. This review focuses on recent findings on the role of glial cells in itch. Central glia (astrocytes and microglia) and peripheral glia (satellite glial cells and Schwann cells) are found to contribute to the development or persistence of itch. Hence, glial modulation has been proposed as a potential option in CI treatment. In experimental models of itch, the blockade of signal transducer and the activator of transcription (STAT) 3-mediated reactive astrogliosis have been shown to suppress chronic itch. Administration of a microglial inhibitor, minocycline, has also been demonstrated to suppress itch-related microglial activation and itch. In sensory ganglia, gap-junction blockers have successfully blocked itch, and hence, gap-junction-mediated coupling, with a potential role of satellite glial cells have been proposed. This review presents examples of glial involvement in itch and opportunities and challenges of glial modulation for targeting itch. Full article

Contemporary research has found that people with autism spectrum disorder (ASD) exhibit aberrant immunological function, with a shift toward increased cytokine production and unusual cell function. Microglia and astroglia were found to be significantly activated in immuno-cytochemical studies, and cytokine analysis revealed that the macrophage chemoattractant protein-1 (MCP-1), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and transforming growth factor β-1 (TGFB-1), all generated in the neuroglia, constituted the most predominant cytokines in the brain. Taurine (2-aminoethanesulfonic acid) is a promising therapeutic molecule able to increase the activity of antioxidant enzymes and ATPase, which may be protective against aluminum-induced neurotoxicity. It can also stimulate neurogenesis, synaptogenesis, and reprogramming of proinflammatory M1 macrophage polarization by decreasing mitophagy (mitochondrial autophagy) and raising the expression of the markers of the anti-inflammatory and pro-healing M2 macrophages, such as macrophage mannose receptor (MMR, CD206) and interleukin 10 (IL-10), while lowering the expression of the M1 inflammatory factor genes. Taurine also induces autophagy, which is a mechanism that is impaired in microglia cells and is critically associated with the pathophysiology of ASD. We hypothesize here that taurine could reprogram the metabolism of M1 macrophages that are overstimulated in the nervous system of people suffering from ASD, thereby decreasing the neuroinflammatory process characterized by autophagy impairment (due to excessive microglia activation), neuronal death, and improving cognitive functions. Therefore, we suggest that taurine can serve as an important lead for the development of novel drugs for ASD treatment. Full article