Deciphering the mechanism of cimifugin in mitigating LPS-induced neuroinflammation in BV-2 cells.

PURPOSE: Sepsis often triggers a systemic inflammatory response leading to multi-organ dysfunction, with complex and not fully understood pathogenesis. This study investigates the therapeutic effects of cimifugin on BV-2 cells under sepsis-induced stress conditions. METHODS: We utilized a BV-2 microglial cell model treated with lipopolysaccharide (LPS) to mimic sepsis. Assessments included cellular vitality, inflammatory cytokine quantification (6 interleukin [6IL]-1ß, interleukin 6 [IL-6], and tumor necrosis factor-α [TNF-α]) via enzyme-linked-immunosorbent serologic assay, and analysis of mRNA expression using real-time polymerase chain reaction. Oxidative stress and mitochondrial function were also evaluated to understand the cellular effects of cimifugin. RESULTS: Cimifugin significantly attenuated LPS-induced inflammatory responses, oxidative stress, and mitochondrial dysfunction. It enhanced cell viability and modulated the secretion and gene expression of inflammatory cytokines IL-1ß, IL-6, and TNF-α. Notably, cimifugin activated the deacetylase sirtuin 1-nuclear factor erythroid 2-related factor 2 pathway, contributing to its protective effects against mitochondrial damage. CONCLUSION: Cimifugin demonstrates the potential of being an effective treatment for sepsis--induced neuroinflammation, warranting further investigation.

Neuroimmune Dysfunction in Alzheimer's Disease and Other Forms of Dementia.

Alzheimer's disease (AD) is a common form of dementia. Although the causal mechanisms of AD are not fully understood, intracerebral accumulation of amyloid beta (Aß) and tau aggregates seems to play an important role in disease development. Therefore, numerous experimental and clinical studies targeting the Aß and tau proteins have been performed. However, these treatments have not achieved good clinical results. Additionally, recent findings have indicated that immune abnormalities contribute to the pathogenesis of AD. Several immune- and microglia-related genes have been identified as putative causative genes for the disease. Microglia, which are resident immune cells in the central nervous system (CNS), are key players that maintain brain homeostasis by communicating with other cells, such as astrocytes and immune cells, in or around the CNS. Furthermore, dysfunction of microglia and the immune system of the CNS could lead to chronic neuroinflammation and impairment of protective neuroimmune responses, which have been associated with the pathogenesis of AD and other forms of dementia. In this review, we assemble information regarding genetic evidence, imaging and biofluid biomarkers, and the pathophysiology of AD, especially highlighting bilateral (protective or detrimental) microglial functions, thus connecting neuroimmune dysfunction and AD. We also introduce candidate drugs to target neuroimmune dysfunction in AD. Finally, we discuss future therapeutic precision medicine approaches for AD, which could be achieved by identifying and targeting signals critical for AD pathogenesis through analyses of interactions between genetic risk factors, as well as identifying and modulating disease-relevant immune cell populations.

Vaccination reduces central nervous system IL-1ß and memory deficits after COVID-19 in mice.

Up to 25% of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibit postacute cognitive sequelae. Although millions of cases of coronavirus disease 2019 (COVID-19)-mediated memory dysfunction are accumulating worldwide, the underlying mechanisms and how vaccination lowers risk are unknown. Interleukin-1 (IL-1), a key component of innate immune defense against SARS-CoV-2 infection, is elevated in the hippocampi of individuals with COVID-19. Here we show that intranasal infection of C57BL/6J mice with SARS-CoV-2 Beta variant leads to central nervous system infiltration of Ly6Chi monocytes and microglial activation. Accordingly, SARS-CoV-2, but not H1N1 influenza virus, increases levels of brain IL-1ß and induces persistent IL-1R1-mediated loss of hippocampal neurogenesis, which promotes postacute cognitive deficits. Vaccination with a low dose of adenoviral-vectored spike protein prevents hippocampal production of IL-1ß during breakthrough SARS-CoV-2 infection, loss of neurogenesis and subsequent memory deficits. Our study identifies IL-1ß as one potential mechanism driving SARS-CoV-2-induced cognitive impairment in a new mouse model that is prevented by vaccination.

MiRNA let-7d-5p Alleviates Inflammatory Responses by Targeting Map3k1 and Inactivating ERK/p38 MAPK Signaling in Microglia.

Alzheimer's disease (AD) is the most common form of dementia. Aberrant regulation of microRNAs (miRNAs) has been implicated in the pathogenesis of AD. In a large case-control study recruiting 208 patients with AD and 205 elderly control subjects, miRNA-let-7d-5p attracted our attention for its downregulated level in patients with AD. However, the biological functions of let-7d-5p in AD pathogenesis have not been investigated. This study emphasized the functions and mechanisms of let-7d-5p in the pathogenesis of AD. Mouse microglial BV2 cells treated with amyloid-ß (Aß)1-42 were used as in vitro AD inflammation models. We reported that let-7d-5p was downregulated in Aß1-42-stimulated BV2 cells, and upregulation of let-7d-5p promoted the transversion of microglial cells from Ml phenotype to M2 phenotype. Then, the binding relationship between let-7d-5p and Map3k1 was verified by luciferase reporter assays. Mechanistically, let-7d-5p could target Map3k1 3'UTR to inactivate ERK/p38 MAPK signaling. Therefore, it was suggested that let-7d-5p might be a novel modulator of microglial neuroinflammation and serve as a novel target for diagnosis and treatment of AD.

Not so aDAMant after all: Plasticity of phagocytic microglia.

Phagocytic microglia such as proliferative region-associated microglia and disease-associated microglia appear in the brain transiently during development and across various brain pathologies, but their function and degree of plasticity remain unclear. In this issue of Immunity, Barclay et al. established a novel Clec7a-CreERT2 mouse line to uncover the plasticity of this cell state and its role in a model of myelin injury.

Associations of the immune system in aggression traits and the role of microglia as mediators.

There is an important relationship between the immune system and aggressive behavior. Aggressive encounters acutely increase the levels of proinflammatory cytokines, and there are positive correlations between aggressive traits and peripheral proinflammatory cytokines. Endotoxin lipopolysaccharide (LPS) treatment, which results in peripheral immune activation, decreases aggressive behavior as one of the sickness behavioral symptoms. In contrast, certain brain infections and chronic interferon treatment are associated with increased aggression. Indeed, the effects of proinflammatory cytokines on the brain in aggressive behavior are bidirectional, depending on the type and dose of cytokine, target brain region, and type of aggression. Some studies have suggested that microglial activation and neuroinflammation influence intermale aggression in rodent models. In addition, pathological conditions as well as physiological levels of cytokines produced by microglia play an important role in social and aggressive behavior in adult animals. Furthermore, microglial function in early development is necessary for the establishment of the social brain and the expression of juvenile social behaviors, including play fighting. Overall, this review discusses the important link between the immune system and aggressive traits and the role of microglia as mediators of this link.

Human NMO-IgG Induced Different Pathological and Immunological Changes in the CNS and Peripheral Tissues of Mice.

OBJECTIVES: The majority of neuromyelitis optica spectrum disorders (NMOSD) patients are seropositive for aquaporin-4 (AQP4)-specific antibodies [also named neuromyelitis optica immunoglobulin G antibodies (NMO-IgG)]. Although NMO-IgG can induce pathological changes in the central nervous system (CNS), the immunological changes in the CNS and peripheral tissue remain largely unknown. We investigated whether NMO-IgG binds to tissue expressing AQP4 and induces immunological changes in the peripheral tissue and CNS. METHODS: C57BL/6 female mice were assigned into an NMOSD or control group. Pathological and immunological changes in peripheral tissue and CNS were measured by immunostaining and flow cytometry, respectively. Motor impairment was measured by open-field test. RESULTS: We found that NMO-IgG did bind to astrocyte- and AQP4-expressing peripheral tissue, but induced glial fibrillary acidic protein and AQP4 loss only in the CNS. NMO-IgG induced the activation of microglia and modulated microglia polarization toward the classical (M1) phenotype, but did not affect innate or adaptive immune cells in the peripheral immune system, such as macrophages, neutrophils, Th17/Th1, or IL-10-producing B cells. In addition, NMOSD mice showed significantly less total distance traveled and higher immobility time in the open field. CONCLUSIONS: We found that injection of human NMO-IgG led to astrocytopathic lesions with microglial activation in the CNS. However, there were no significant pathological or immunological changes in the peripheral tissues.

Fetal brain response to maternal inflammation requires microglia.

In utero infection and maternal inflammation can adversely impact fetal brain development. Maternal systemic illness, even in the absence of direct fetal brain infection, is associated with an increased risk of neuropsychiatric disorders in affected offspring. The cell types mediating the fetal brain response to maternal inflammation are largely unknown, hindering the development of novel treatment strategies. Here, we show that microglia, the resident phagocytes of the brain, highly express receptors for relevant pathogens and cytokines throughout embryonic development. Using a rodent maternal immune activation (MIA) model in which polyinosinic:polycytidylic acid is injected into pregnant mice, we demonstrate long-lasting transcriptional changes in fetal microglia that persist into postnatal life. We find that MIA induces widespread gene expression changes in neuronal and non-neuronal cells; importantly, these responses are abolished by selective genetic deletion of microglia, indicating that microglia are required for the transcriptional response of other cortical cell types to MIA. These findings demonstrate that microglia play a crucial durable role in the fetal response to maternal inflammation, and should be explored as potential therapeutic cell targets.

Microglial mediators in autoimmune Uveitis: Bridging neuroprotection and neurotoxicity.

Autoimmune uveitis, a severe inflammatory condition of the eye, poses significant challenges due to its complex pathophysiology and the critical balance between protective and detrimental immune responses. Central to this balance are microglia, the resident immune cells of the central nervous system, whose roles in autoimmune uveitis are multifaceted and dynamic. This review article delves into the dual nature of microglial functions, oscillating between neuroprotective and neurotoxic outcomes in the context of autoimmune uveitis. Initially, we explore the fundamental aspects of microglia, including their activation states and basic functions, setting the stage for a deeper understanding of their involvement in autoimmune uveitis. The review then navigates through the intricate mechanisms by which microglia contribute to disease onset and progression, highlighting both their protective actions in immune regulation and tissue repair, and their shift towards a pro-inflammatory, neurotoxic profile. Special emphasis is placed on the detailed pathways and cellular interactions underpinning these dual roles. Additionally, the review examines the potential of microglial markers as diagnostic and prognostic indicators, offering insights into their clinical relevance. The article culminates in discussing future research directions, and the ongoing challenges in translating these findings into effective clinical applications. By providing a comprehensive overview of microglial mechanisms in autoimmune uveitis, this review underscores the critical balance of microglial activities and its implications for disease management and therapy development.

Targeting the HSP47-collagen axis inhibits brain metastasis by reversing M2 microglial polarization and restoring anti-tumor immunity.

Brain metastases (BrMs) are the leading cause of death in patients with solid cancers. BrMs exhibit a highly immunosuppressive milieu and poor response to immunotherapies; however, the underlying mechanism remains largely unclear. Here, we show that upregulation of HSP47 in tumor cells drives metastatic colonization and outgrowth in the brain by creating an immunosuppressive microenvironment. HSP47-mediated collagen deposition in the metastatic niche promotes microglial polarization to the M2 phenotype via the α2ß1 integrin/nuclear factor κB pathway, which upregulates the anti-inflammatory cytokines and represses CD8+ T cell anti-tumor responses. Depletion of microglia reverses HSP47-induced inactivation of CD8+ T cells and abolishes BrM. Col003, an inhibitor disrupting HSP47-collagen association restores an anti-tumor immunity and enhances the efficacy of anti-PD-L1 immunotherapy in BrM-bearing mice. Our study supports that HSP47 is a critical determinant of M2 microglial polarization and immunosuppression and that blocking the HSP47-collagen axis represents a promising therapeutic strategy against brain metastatic tumors.

PolyI:C Maternal Immune Activation on E9.5 Causes the Deregulation of Microglia and the Complement System in Mice, Leading to Decreased Synaptic Spine Density.

Maternal immune activation (MIA) is a risk factor for multiple neurodevelopmental disorders; however, animal models developed to explore MIA mechanisms are sensitive to experimental factors, which has led to complexity in previous reports of the MIA phenotype. We sought to characterize an MIA protocol throughout development to understand how prenatal immune insult alters the trajectory of important neurodevelopmental processes, including the microglial regulation of synaptic spines and complement signaling. We used polyinosinic:polycytidylic acid (polyI:C) to induce MIA on gestational day 9.5 in CD-1 mice, and measured their synaptic spine density, microglial synaptic pruning, and complement protein expression. We found reduced dendritic spine density in the somatosensory cortex starting at 3-weeks-of-age with requisite increases in microglial synaptic pruning and phagocytosis, suggesting spine density loss was caused by increased microglial synaptic pruning. Additionally, we showed dysregulation in complement protein expression persisting into adulthood. Our findings highlight disruptions in the prenatal environment leading to alterations in multiple dynamic processes through to postnatal development. This could potentially suggest developmental time points during which synaptic processes could be measured as risk factors or targeted with therapeutics for neurodevelopmental disorders.

Priming of hippocampal microglia by IFN-γ/STAT1 pathway impairs social memory in mice.

Social behavior is inextricably linked to the immune system. Although IFN-γ is known to be involved in social behavior, yet whether and how it encodes social memory remains unclear. In the current study, we injected with IFN-γ into the lateral ventricle of male C57BL/6J mice, and three-chamber social test was used to examine the effects of IFN-γ on their social preference and social memory. The morphology of microglia in the hippocampus, prelimbic cortex and amygdala was examined using immunohistochemistry, and the phenotype of microglia were examined using immunohistochemistry and enzyme-linked immunosorbent assays. The IFN-γ-injected mice were treated with lipopolysaccharide, and effects of IFN-γ on behavior and microglial responses were evaluated. STAT1 pathway and microglia-neuron interactions were examined in vivo or in vitro using western blotting and immunohistochemistry. Finally, we use STAT1 inhibitor or minocycline to evaluated the role of STAT1 in mediating the microglial priming and effects of primed microglia in IFN-γ-induced social dysfunction. We demonstrated that 500 ng of IFN-γ injection results in significant decrease in social index and social novelty recognition index, and induces microglial priming in hippocampus, characterized by enlarged cell bodies, shortened branches, increased expression of CD68, CD86, CD74, CD11b, CD11c, CD47, IL-33, IL-1ß, IL-6 and iNOS, and decreased expression of MCR1, Arg-1, IGF-1 and BDNF. This microglia subpopulation is more sensitive to LPS challenge, which characterized by more significant morphological changes and inflammatory responses, as well as induced increased sickness behaviors in mice. IFN-γ upregulated pSTAT1 and STAT1 and promoted the nuclear translocation of STAT1 in the hippocampal microglia and in the primary microglia. Giving minocycline or STAT1 inhibitor fludarabin blocked the priming of hippocampal microglia induced by IFN-γ, ameliorated the dysfunction in hippocampal microglia-neuron interactions and synapse pruning by microglia, thereby improving social memory deficits in IFN-γ injected mice. IFN-γ initiates STAT1 pathway to induce priming of hippocampal microglia, thereby disrupts hippocampal microglia-neuron interactions and neural circuit link to social memory. Blocking STAT1 pathway or inhibiting microglial priming may be strategies to reduce the effects of IFN-γ on social behavior.

Ciita Regulates Local and Systemic Immune Responses in a Combined rAAV-α-synuclein and Preformed Fibril-Induced Rat Model for Parkinson's Disease.

Background: Parkinson's disease (PD) is characterized by alpha-synuclein (α-Syn) pathology, neurodegeneration and neuroinflammation. Human leukocyte antigen (HLA) variants associated with PD and α-Syn specific CD4+ T lymphocytes in PD patients highlight the importance of antigen presentation in PD etiology. The class II transactivator (CIITA) regulates major histocompatibility complex class II (MHCII) expression. Reduced Ciita levels significantly increase α-Syn pathology, nigrostriatal neurodegeneration and behavioral deficits in α-Syn-induced rat PD models. Objective: Characterize immune profiles associated with enhanced PD-like pathology observed in rats expressing lower Ciita levels (DA.VRA4) compared to the background strain (DA). Methods: To model PD, we combined rAAV-mediated α-Syn overexpression in the substantia nigra with striatal injection of α-Syn preformed fibrils. Immune profiles in brain and blood were analyzed by flow cytometry and multiplexed ELISA in naïve rats, 4- and 8 weeks post rAAV injection. Results: Flow cytometry showed Ciita-dependent regulation of MHCII on microglia, brain macrophages and circulating myeloid cells. The MHCII-dependent microglial response was highest at 4 weeks post rAAV injection, whereas the MHCII levels in circulating myeloid cells was highest at 8 weeks. There was no major infiltration of macrophages or T lymphocytes into the CNS in response to α-Syn and only subtle Ciita- and/or α-Syn-dependent changes in the T lymphocyte compartment. Lower Ciita levels were consistently associated with higher TNF levels in serum. Conclusions: Ciita regulates susceptibility to PD-like pathology through minor but detectable changes in resident and peripheral immune cells and TNF levels, indicating that mild immunomodulatory therapies could have therapeutic effects in PD.

Parkinson's disease is characterized by loss of nerve cells. There is also abnormal aggregation of a protein called alpha-synuclein and an ongoing inflammatory response. Findings that immune cells in the blood of individuals with Parkinson's disease react against the alpha-synuclein protein and that genes important for the immune system affect the risk of developing Parkinson's disease indicate that immune responses are important in Parkinson's disease. We have previously found that a low expression of certain immune molecules worsens disease progression in a rat model of Parkinson's disease. The aim of this study was to identify changes in the immune system in rats that are associated with disease severity, to identify mechanisms that could be targeted to treat Parkinson's disease. To model Parkinson's disease, we injected a modified virus to produce large amounts of alpha-synuclein combined with an injection of aggregated alpha-synuclein proteins in the rat brain. The model mimics several features of Parkinson's disease including nerve cell death, problems with movement, accumulation of alpha-synuclein in the brain, and an immune response. We observed that the immune system in the brain and blood responded to the model but that differences were small compared to controls. Our results suggest that small changes in the immune system can have a large effect on disease progression and that therapies targeting the immune system are worth exploring to find better treatment for Parkinson's disease.

Aspartame-induced cognitive dysfunction: Unveiling role of microglia-mediated neuroinflammation and molecular remediation.

Aspartame, an artificial sweetener, is consumed by millions of people globally. There are multiple reports of aspartame and its metabolites affecting cognitive functions in animal models and humans, which include learning problems, headaches, seizures, migraines, irritable moods, anxiety, depression, and insomnia. These cognitive deficits and associated symptoms are partly attributed to dysregulated excitatory and inhibitory neurotransmitter balance due to aspartate released from aspartame, resulting in an excitotoxic effect in neurons, leading to neuronal damage. However, microglia, a central immunocompetent cell type in brain tissue and a significant player in inflammation can contribute to the impact. Microglia rapidly respond to changes in CNS homeostasis. Aspartame consumption might affect the microglia phenotype directly via methanol-induced toxic effects and indirectly via aspartic acid-mediated excitotoxicity, exacerbating symptoms of cognitive decline. Long-term oral consumption of aspartame thus might change microglia's phenotype from ramified to activated, resulting in chronic or sustained activation, releasing excess pro-inflammatory molecules. This pro-inflammatory surge might lead to the degeneration of healthy neurons and other glial cells, impairing cognition. This review will deliberate on possible links and research gaps that need to be explored concerning aspartame consumption, ecotoxicity and microglia-mediated inflammatory cognitive impairment. The study covers a comprehensive analysis of the impact of aspartame consumption on cognitive function, considering both direct and indirect effects, including the involvement of microglia-mediated neuroinflammation. We also propose a novel intervention strategy involving tryptophan supplementation to mitigate cognitive decline symptoms in individuals with prolonged aspartame consumption, providing a potential solution to address the adverse effects of aspartame on cognitive function.

Mesenchymal Stem Cells-based Cell-free Therapy Targeting Neuroinflammation.

Emerging from several decades of extensive research, key genetic elements and biochemical mechanisms implicated in neuroinflammation have been delineated, contributing substantially to our understanding of neurodegenerative diseases (NDDs). In this minireview, we discuss data predominantly from the past three years, highlighting the pivotal roles and mechanisms of the two principal cell types implicated in neuroinflammation. The review also underscores the extended process of peripheral inflammation that predates symptomatic onset, the critical influence of neuroinflammation, and their dynamic interplay in the pathogenesis of NDDs. Confronting these complex challenges, we introduce compelling evidence supporting the use of mesenchymal stem cell-based cell-free therapy. This therapeutic strategy includes the regulation of microglia and astrocytes, modulation of peripheral nerve cell inflammation, and targeted anti-inflammatory interventions specifically designed for NDDs, while also discussing engineering and safety considerations. This innovative therapeutic approach intricately modulates the immune system across the peripheral and nervous systems, with an emphasis on achieving superior penetration and targeted delivery. The insights offered by this review have significant implications for the better understanding and management of neuroinflammation.

Multiple Synergistic Effects of the Microglia Membrane-Bionic Nanoplatform on Mediate Tumor Microenvironment Remodeling to Amplify Glioblastoma Immunotherapy.

Glioblastoma (GBM) is a lethal brain tumor with high levels of malignancy. Most chemotherapy agents show serious systemic cytotoxicity and restricted delivery effectiveness due to the impediments of the blood-brain barrier (BBB). Immunotherapy has developed great potential for aggressive tumor treatments. Disappointingly, its efficacy against GBM is hindered by the immunosuppressive tumor microenvironment (TME) and BBB. Herein, a multiple synergistic immunotherapeutic strategy against GBM was developed based on the nanomaterial-biology interaction. We have demonstrated that this BM@MnP-BSA-aPD-1 can transverse the BBB and target the TME, resulting in amplified synergetic effects of metalloimmunotherapy and photothermal immunotherapy (PTT). The journey of this nanoformulation within the TME contributed to the activation of the stimulator of the interferon gene pathway, the initiation of the immunogenic cell death effect, and the inhibition of the programmed cell death-1/programmed cell death ligand 1 (PD-1/PD-L1) signaling axis. This nanomedicine revitalizes the immunosuppressive TME and evokes the cascade effect of antitumor immunity. Therefore, the combination of BM@MnP-BSA-aPD-1 and PTT without chemotherapeutics presents favorable benefits in anti-GBM immunotherapy and exhibits immense potential for clinical translational applications.

Single-cell transcriptome reveals highly complement activated microglia cells in association with pediatric tuberculous meningitis.

Background: Tuberculous meningitis (TBM) is a devastating form of tuberculosis (TB) causing high mortality and disability. TBM arises due to immune dysregulation, but the underlying immune mechanisms are unclear. Methods: We performed single-cell RNA sequencing on peripheral blood mononuclear cells (PBMCs) and cerebrospinal fluid (CSF) cells isolated from children (n=6) with TBM using 10 xGenomics platform. We used unsupervised clustering of cells and cluster visualization based on the gene expression profiles, and validated the protein and cytokines by ELISA analysis. Results: We revealed for the first time 33 monocyte populations across the CSF cells and PBMCs of children with TBM. Within these populations, we saw that CD4_C04 cells with Th17 and Th1 phenotypes and Macro_C01 cells with a microglia phenotype, were enriched in the CSF. Lineage tracking analysis of monocyte populations revealed myeloid cell populations, as well as subsets of CD4 and CD8 T-cell populations with distinct effector functions. Importantly, we discovered that complement-activated microglial Macro_C01 cells are associated with a neuroinflammatory response that leads to persistent meningitis. Consistently, we saw an increase in complement protein (C1Q), inflammatory markers (CRP) and inflammatory factor (TNF-α and IL-6) in CSF cells but not blood. Finally, we inferred that Macro_C01 cells recruit CD4_C04 cells through CXCL16/CXCR6. Discussion: We proposed that the microglial Macro_C01 subset activates complement and interacts with the CD4_C04 cell subset to amplify inflammatory signals, which could potentially contribute to augment inflammatory signals, resulting in hyperinflammation and an immune response elicited by Mtb-infected tissues.

Ischemic stroke outcome after promoting CD4+CD25+ Treg cell migration through CCR4 overexpression in a tMCAO animal model.

The importance of neuroinflammation during the ischemic stroke has been extensively studied. The role of CD4+CD25+ regulatory T (Treg) cells during the recovery phase have shown infarct size reduction and functional improvement, possibly through the mitigation of inflammatory immune responses. We aimed to investigate the molecular factors involved in microglia-Treg cell communication that result in Treg trafficking. First, we observed the migration patterns of CD8+ (cytotoxic) T cells and Treg cells and then searched for chemokines released by activated microglia in an oxygen-glucose deprivation (OGD) model. The transwell migration assay showed increased migration into OGD media for both cell types, in agreement with the increase in chemokines involved in immune cell trafficking from the mouse chemokine profiling array. MSCV retrovirus was transduced to overexpress CCR4 in Treg cells. CCR4-overexpressed Treg cells were injected into the mouse transient middle cerebral artery occlusion (tMCAO) model to evaluate the therapeutic potential via the tetrazolium chloride (TTC) assay and behavioral tests. A general improvement in the prognosis of animals after tMCAO was observed. Our results suggest the increased mobility of CCR4-overexpressed Treg cells in response to microglia-derived chemokines in vitro and the therapeutic potential of Treg cells with increased mobility in cellular therapy.

Glucose-driven histone lactylation promotes the immunosuppressive activity of monocyte-derived macrophages in glioblastoma.

Immunosuppressive macrophages restrict anti-cancer immunity in glioblastoma (GBM). Here, we studied the contribution of microglia (MGs) and monocyte-derived macrophages (MDMs) to immunosuppression and mechanisms underlying their regulatory function. MDMs outnumbered MGs at late tumor stages and suppressed T cell activity. Molecular and functional analysis identified a population of glycolytic MDM expressing GLUT1 with potent immunosuppressive activity. GBM-derived factors promoted high glycolysis, lactate, and interleukin-10 (IL-10) production in MDMs. Inhibition of glycolysis or lactate production in MDMs impaired IL-10 expression and T cell suppression. Mechanistically, intracellular lactate-driven histone lactylation promoted IL-10 expression, which was required to suppress T cell activity. GLUT1 expression on MDMs was induced downstream of tumor-derived factors that activated the PERK-ATF4 axis. PERK deletion in MDM abrogated histone lactylation, led to the accumulation of intratumoral T cells and tumor growth delay, and, in combination with immunotherapy, blocked GBM progression. Thus, PERK-driven glucose metabolism promotes MDM immunosuppressive activity via histone lactylation.

Modeling HIV-1 Infection in CNS via Infected Monocytes Using Immunocompetent Brain Organoids.

The development of 3D-organoid models has revolutionized the way diseases are studied. Recently, our brain organoid model has been shown to recapitulate in in vitro the human brain cytoarchitecture originally encountered in HIV-1 neuropathogenesis, allowing downstream applications. Infected monocytes, macrophages, and microglia are critically important immune cells for infection and dissemination of HIV-1 throughout brain during acute and chronic phase of the disease. Once in the brain parenchyma, long-lived infected monocytes/macrophages along with resident microglia contribute to the establishment of CNS latency in people with HIV (PWH). Hence, it is important to better understand how HIV-1 enters and establishes infection and latency in CNS to further develop cure strategies. Here we detailed an accessible protocol to incorporate monocytes (infected and/or labeled) as a model of transmigration of peripheral monocytes into brain organoids that can be applied to characterize HIV-1 neuroinvasion and virus dissemination.