Biology subjects

Eyo, U. B.

Publications and source records attributed to Eyo, U. B..

10 recordsLinked to original sources

bioRxiv2025

Microglia and its P2RY12 Receptors Regulate Seizure Severity

Microglia have emerged as possible regulators of seizures with previous approaches employed being insufficiently selective of microglial-specific contributions. To more definitely determine microglial roles in seizure severity, we used the recently developed genetic microglial-deficient Csf1r{Delta}FIRE/{Delta}FIRE (FIRE KO) mouse model. In this model, mice lack microglia but retain brain border associated macrophages (BAMs). Using two experimental seizure paradigms with either a chemoconvulsant or electrical stimulation, we confirm that a microglial deficiency exacerbates seizures, reduces survival and facilitates the likelihood of developing spontaneous recurrent seizures, indicating that microglia constrain seizure activity across different seizure paradigms. To gain insights into molecular regulators of seizure severity under microglial regulation, we examined P2RY12 contributions and demonstrate that a loss of microglial P2RY12 increased seizure severity in both global and microglial-specific knockout mice indicating that microglia suppress seizure severity in chemoconvulsive models through P2RY12 signaling. During seizures, P2RY12-deficient microglia displayed altered process complexity, accompanied by increased neuronal activation and reduced inhibitory tone. These results link impaired microglial responses to heightened seizure susceptibility and network excitability. Together, our findings establish microglia as protective regulators of seizure activity and identify P2RY12 signaling as a critical mediator of microglia protective actions.

neuroscience↗

bioRxiv2025

Helminth infection induces neuroimmune remodeling and clinical remission in a mouse model of multiple sclerosis

The central nervous system (CNS) is under constant immunosurveillance and influenced by immune-related effector molecules, including type 2-associated cytokines. Long-lasting type 2 immunity elicited by intestinal helminth infections can modify immune responses and wound repair locally and in peripheral tissues, but direct effects of helminth infection on the CNS are poorly understood. Here, we explore whether naturally-evoked type 2 immune responses can modify neuroimmune interactions for therapeutic gain in a mouse model of multiple sclerosis. Chronic infection with the helminth Trichinella spiralis (Ts) remodelled the neuroimmune landscape, including establishment of a robust population of CNS-resident T helper 2 cells, which subsequently minimized CNS inflammation and demyelination during experimental autoimmune encephalomyelitis (EAE). Clinical remission could be achieved with prophylactic or therapeutic infection, was Stat6-dependent, and adoptive transfer of Th2 cells promoted remission in the absence of overt infection. These findings highlight the potential for harnessing type 2 immunity to modify outcomes of neuroinflammation and neurodegeneration. SummaryFettig et al. demonstrate that infection with the helminth Trichinella spiralis elicits rapid recruitment and sustained presence of Th2 cells in the central nervous system where they modify microglia function and are implicated in resolving autoimmune-mediated paralysis and neuroinflammation.

immunology↗

bioRxiv2025

Multimodal analysis identifies pericyte-centered signaling programs altered by sex and brain region in Alzheimer's Disease

Pericytes are critical components of the neurovascular unit (NVU), regulating endothelial cell (EC) stability, blood-brain barrier (BBB) integrity, and neuroimmune signaling. However, their role in Alzheimers Disease (AD), particularly in the context of sex differences and brain region specificity, remains poorly defined. Here, we use single-nucleus RNA sequencing (snRNA-seq) to characterize transcriptional and intercellular signaling changes in pericytes across the middle temporal gyrus (MTG) and dorsolateral prefrontal cortex (DLPFC) of the same AD and non-AD donors, stratified by sex. Using LIANA and Tensor-cell2cell, we identify latent communication programs altered in female AD donors, including a pericyte-EC signaling pattern that activates TGF{beta} via extracellular matrix ligands and is upregulated in the MTG but not the DLPFC. A second communication pattern, downregulated in female AD donors, reveals impaired estrogen pathway signaling through ligand-receptor interactions between pericytes and astrocytes. Supporting this, we observe reduced expression of pericyte-derived neuroligins and increased pericyte-astrocyte separation in a spatial transcriptomic subset. Additionally, we identify a microglia-to-pericyte signaling program conserved across brain regions, enriched for inflammatory pathways including hypoxia and p53, and elevated in both male and female AD donors with regional specificity. This result contrasts with the more sex-and region-specific pericyte signaling programs and suggests parallel mechanisms of NVU disruption between brain regions in AD. Our findings reveal brain region-specific and sex-specific pericyte signaling changes in AD and implicate vascular-, immune-, and synapse-associated pathways in NVU dysfunction. Altogether, the data suggest pericyte-driven communication as a mechanistic contributor to female-biased vulnerability in AD and support the need for sex-aware and region-specific approaches in neurodegeneration research.

bioinformatics↗

bioRxiv2025

Transcriptional Regulation of Microglial Metabolic and Activation States by P2RY12

Microglia are the resident immune cells of the CNS. Under homeostatic conditions, Microglia play critical roles orchestrating synaptic pruning, debris clearance and dead cells removals. In disease, they are powerful mediators of neuroinflammation, as they rapidly respond to injury or infection within the CNS by altering their morphology, proliferating, and releasing cytokines and other signaling molecules. Understanding the molecular pathways involved in microglial function is pivotal for advancing neurobiological research and developing effective strategies for CNS disorders. In this context, P2RY12 is a G protein-coupled receptor (GPCR) that is uniquely enriched in microglia in the parenchyma and a canonical marker of homeostatic, ramified microglia. However, P2RY12 is downregulated in activated microglia and in neurological conditions. The consequences of P2RY12 downregulation in disease-associated microglia and how they influence microglial activation remain poorly understood. In this study, we apply transcriptional and histological methods to explore the changes to microglia upon a genetic P2RY12 loss. Our findings reveal that P2RY12-deficient microglia experience alterations in distinct metabolic pathways while preserving overall homeostatic microglial transcriptional identity. Lack of P2RY12 alters signature genes involved in homeostatic iron metabolism. Importantly, the genes encoding proteins in the Glutathione Peroxidase 4 (Gpx4)-Glutathione (GSH) antioxidant pathway related to ferroptosis susceptibility are impaired upon microglial activation with lipopolysaccharide (LPS) treatment. These results highlight the critical role of P2RY12 in regulating microglial immune and metabolic transcriptional responses under both homeostatic and inflammatory conditions, providing insights into its involvement in CNS pathophysiology. Proposed Model O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/665960v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@176a44corg.highwire.dtl.DTLVardef@1ca463org.highwire.dtl.DTLVardef@6c68dforg.highwire.dtl.DTLVardef@15913f9_HPS_FORMAT_FIGEXP M_FIG C_FIG At basal condition the transcriptional landscape of P2RY12-deficient microglia suggests that the cell is in a highly demanding metabolic state with increased oxidative phosphorylation and glycolysis as well as augmented expression of ribosomal proteins involved in cytoplasmic translation. Additionally, P2RY12-deficient microglia exhibit heightened expression of key regulators of the antioxidant response, suggesting elevated ROS levels as a consequence of this highly metabolically active and energetically demanding microglial state. Elevated ROS levels might diminish microglial antioxidant reserves thus rendering them more vulnerable to additional oxidative stress pushing the redox balance. When activated by LPS treatment, P2RY12-deficient microglia exhibit an impaired responsiveness of system xc and downstream enzymes involved in GSH mediated antioxidant response that together with LPS induced intracellular iron sequestration(Francois et al., 2014; S. Liu, Gao, & Zhou, 2022; McCarthy et al., 2018; Sfera et al., 2018; Shin et al., 2018; Urrutia et al., 2013) suggesting that P2RY12-deficient microglia will show increased susceptibility to ferroptosis. It is possible that system xc unresponsiveness in KO microglia results from the upregulation of ribosomal proteins involved in the inhibition of MD2, a negative regulator of p53 DNA binding activity(Daftuar, Zhu, Jacq, & Prives, 2013). In this sense, the repression of p53 inhibition will enhance its function, possibly explaining a suppression of Slc7a11 expression in LPS-activated P2RY12 deficient microglia.

neuroscience↗

bioRxiv2025

Knockout of P2Y12 receptor facilitates microglia-neuron body-to-body interactions and accelerates prion disease

Microglia continuously monitor neuronal health through somatic purinergic junctions, where microglial processes establish dynamic contacts with neuronal cell bodies. The P2Y12 receptor is a key component of these junctions, essential for intercellular communication between ramified microglia and neurons under homeostatic conditions. While P2Y12 has long been considered a marker of homeostatic microglia, its potential role in reactive microglia during neurodegenerative disease remains largely unexplored. In this study, we demonstrate that P2Y12 deletion significantly reduces microglia-neuron process-to-body contacts in adult mice, consistent with previous findings. However, unexpectedly, P2Y12 loss markedly increases microglia-neuron body-to-body contacts, revealing an alternative mode of microglia-neuron communication independent of P2Y12. In prion-infected mice, P2Y12 expression persists in reactive, amoeboid microglia during advanced disease stages, including those engaging in extensive neuronal envelopment. Notably, P2Y12 loss increases the prevalence of envelopment events and accelerates disease progression. These findings redefine the role of P2Y12 in neurodegeneration, suggesting that its progressive decline lowers the threshold for microglia-neuron body-to-body interactions, ultimately influencing disease trajectory.

neuroscience↗

bioRxiv2025

7-ketocholesterol contributes to microglia-driven increases in astrocyte reactive oxygen species in Alzheimer's disease

Oxidative stress is a prominent feature of Alzheimers disease. Within this context, cholesterol undergoes oxidation, producing the pro-inflammatory product 7-ketocholesterol (7-KC). In this study, we observe elevated levels of 7-KC in the brains of the 3xTg mouse model of AD. To further understand the contribution of 7-KC on the oxidative environment, we developed a method to express a genetically encoded fluorescent hydrogen peroxide (H2O2) sensor in astrocytes, the primary source of cholesterol in the brain. With this sensor, we discovered that 7-KC increases H2O2 levels in astrocytes in vivo, but not when directly applied to astrocytes in vitro. Interestingly, when 7-KC was applied to a microglia cell line alone or mixed astrocyte and microglia cultures, it resulted in microglia activation and increased oxidative stress in astrocytes. Depletion of microglia from 3xTg mice resulted in reduced 7-KC in the brains of these mice. Taken together, these findings suggest that 7-KC, acting through microglia, contributes to increased astrocyte oxidative stress in AD. This study sheds light on the complex interplay between cholesterol oxidation, microglia activation, and astrocyte oxidative stress in the pathogenesis of AD.

neuroscience↗

bioRxiv2023

Microglia play beneficial roles in multiple experimental seizure models.

Seizure disorders are common, affecting both the young and the old. Currently available antiseizure drugs are ineffective in a third of patients and have been developed with a focus on known neurocentric mechanisms, raising the need for investigations into alternative and complementary mechanisms that contribute to seizure generation or its containment. Neuroinflammation, broadly defined as the activation of immune cells and molecules in the central nervous system (CNS), has been proposed to facilitate seizure generation, although the specific cells involved in these processes remain inadequately understood. The role of microglia, the primary inflammation-competent cells of the brain, is debated since previous studies were conducted using approaches that were less specific to microglia or had inherent confounds. Using a selective approach to target microglia without such side effects, we show a broadly beneficial role for microglia in limiting chemoconvulsive, electrical, and hyperthermic seizures and argue for a further understanding of microglial contributions to contain seizures.

neuroscience↗

bioRxiv2021

Capillary-associated microglia regulate vascular structure and function through PANX1-P2RY12 coupling

Microglia are brain-resident immune cells with a repertoire of functions in the developing, mature and pathological brain. Their wide-ranging roles in physiology include the clearance of cellular debris, elimination of excess synapses, regulation of neuronal activity and contributions to blood vessel development. Despite these known roles for microglia, the extent of their interactions with the vasculature and potential regulation of vascular physiology has been insufficiently explored. Here, using in vivo acute and longitudinal two-photon imaging in transgenic mice combined with electron microscopy, fixed tissue immunohistochemistry, pharmacological treatments and laser speckle imaging, we document the steady-state interactions between ramified CX3CR1+ myeloid cell somata and capillaries in the brain. We first confirm that these myeloid cells are bona fide microglia by molecular, morphological and ultrastructural approaches. Then we give a detailed spatio-temporal characterization of these capillary-associated microglia (CAMs) comparing and contrasting them with parenchymal microglia (PCMs) in their static, dynamic and chronic morphological activities including during microglial depletion and repopulation. Molecularly, we identify microglial-specific purinergic P2RY12 receptors as a receptor regulating CAM interactions under the control of released purines from pannexin 1 (PANX1) channels. Furthermore, to elucidate roles for microglia in vascular structure and function, we eliminated microglia and showed that this triggered capillary dilation, blood flow increase, and impaired vasodilative responses. We find that P2RY12-/- and PANX1-/- mice recapitulate these vascular impairments suggesting purines released through PANX1 channels play important roles in activating microglial P2RY12 receptors to regulate neurovascular structure and function.

neuroscience↗

bioRxiv2019

Spinal Microglia Contribute to Sustained Inflammatory Pain via Amplifying Neuronal Activity

Microglia are highly dynamic immune cells of the central nervous system (CNS). Microglial processes interact with neuronal elements constantly on the order of minutes. The functional significance of this acute microglia-neuron interaction and its potential role in the context of pain is still largely unknown. Here, we found that spinal microglia increased their process motility and electrophysiological reactivity within an hour after the insult in a mouse model of formalin-induced acute, sustained, inflammatory pain. Using an ablation strategy to specifically deplete resident microglia in the CNS, we demonstrate that microglia participate in formalin-induced acute sustained pain behaviors by amplifying neuronal activity in the spinal dorsal horn. Moreover, we identified that the P2Y12 receptor, which is specifically expressed in microglia in the CNS, was required for microglial function in formalin-induced pain. Taken together, our study provides a novel insight into the contribution of microglia and the P2Y12 receptor in acute, sustained, inflammatory pain that could be used for potential therapeutic strategies.

neuroscience↗

bioRxiv2019

Neuronal network activity controls microglial process surveillance in awake mice via norepinephrine signaling

Microglia are resident immune cells that dynamically survey the brain parenchyma, interacting with neurons in both health and disease. However, it is still unclear how neuronal network activity drives microglial dynamics. Utilizing in vivo two-photon imaging of microglia in awake mice, we found that inhibition of neuronal activity under general anesthesia dramatically increased microglial process surveillance. Accordingly, both sensory deprivation and optogenetic inhibition of local neuronal network activity in awake mice resulted in similar increases in microglial process surveillance. We further determined that reduced norepinephrine signaling is responsible for the observed increase in microglial process surveillance. Our results demonstrate that microglial process dynamics are directly influenced by neural activities through norepinephrine signaling in awake animals and indicate the importance of awake imaging for studying microglia-neuron interactions.

neuroscience↗