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The choroid plexus (ChP) is a vital brain barrier and source of cerebrospinal fluid (CSF). Here, we use longitudinal two-photon imaging in awake mice and single-cell transcriptomics to elucidate the mechanisms of ChP regulation of brain inflammation. We used intracerebroventricular injections of lipopolysaccharides (LPS) to model meningitis in mice and observed that neutrophils and monocytes accumulated in the ChP stroma and surged across the epithelial barrier into the CSF. Bi-directional recruitment of monocytes from the periphery and, unexpectedly, macrophages from the CSF to the ChP helped eliminate neutrophils and repair the barrier. Transcriptomic analyses detailed the molecular steps accompanying this process and revealed that ChP epithelial cells transiently specialize to nurture immune cells, coordinating their recruitment, survival, and differentiation as well as regulation of the tight junctions that control the permeability of the ChP brain barrier. Collectively, we provide a mechanistic understanding and a comprehensive roadmap of neuroinflammation at the ChP brain barrier.
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We discovered that apocrine secretion by embryonic choroid plexus (ChP) epithelial cells contributes to the cerebrospinal fluid (CSF) proteome and influences brain development in mice. The apocrine response relies on sustained intracellular calcium signaling and calpain-mediated cytoskeletal remodeling. It rapidly alters the embryonic CSF proteome, activating neural progenitors lining the brain's ventricles. Supraphysiological apocrine secretion induced during mouse development by maternal administration of a serotonergic 5HT2C receptor agonist dysregulates offspring cerebral cortical development, alters the fate of CSF-contacting neural progenitors, and ultimately changes adult social behaviors. Critically, exposure to maternal illness or to the psychedelic drug LSD during pregnancy also overactivates the ChP, inducing excessive secretion. Collectively, our findings demonstrate a new mechanism by which maternal exposure to diverse stressors disrupts in utero brain development.
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The choroid plexus (ChP) is a vital brain barrier and source of cerebrospinal fluid (CSF). Here, we use chronic two-photon imaging in awake mice and single-cell transcriptomics to demonstrate that in addition to these roles, the ChP is a complex immune organ that regulates brain inflammation. In a mouse meningitis model, neutrophils and monocytes accumulated in ChP stroma and surged across the epithelial barrier into the CSF. Bi-directional recruitment of monocytes from the periphery and, unexpectedly, macrophages from the CSF to the ChP helped eliminate neutrophils and repair the barrier. Transcriptomic analyses detailed the molecular steps accompanying this process, including the discovery of epithelial cells that transiently specialized to nurture immune cells, coordinate their recruitment, survival, and differentiation, and ultimately, control the opening/closing of the ChP brain barrier. Collectively, we provide a new conceptual understanding and comprehensive roadmap of neuroinflammation at the ChP brain barrier.
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Transmission and secretion of signals via the choroid plexus (ChP) brain barrier can modulate brain states via regulation of cerebrospinal fluid (CSF) composition. Here, we developed a platform to analyze diurnal variations in male mouse ChP and CSF. Ribosome profiling of ChP epithelial cells revealed diurnal translatome differences in metabolic machinery, secreted proteins, and barrier components. Using ChP and CSF metabolomics and blood-CSF barrier analyses, we observed diurnal changes in metabolites and cellular junctions. We then focused on transthyretin (TTR), a diurnally regulated thyroid hormone chaperone secreted by the ChP. Diurnal variation in ChP TTR depended on Bmal1 clock gene expression. We achieved real-time tracking of CSF-TTR in awake TtrmNeonGreen mice via multi-day intracerebroventricular fiber photometry. Diurnal changes in ChP and CSF TTR levels correlated with CSF thyroid hormone levels. These datasets highlight an integrated platform for investigating diurnal control of brain states by the ChP and CSF.
Assuntos
Barreira Hematoencefálica , Plexo Corióideo , Camundongos , Masculino , Animais , Plexo Corióideo/metabolismo , Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Hormônios Tireóideos/metabolismo , Pré-Albumina/genética , Pré-Albumina/metabolismo , Transporte BiológicoRESUMO
Post-hemorrhagic hydrocephalus (PHH) refers to a life-threatening accumulation of cerebrospinal fluid (CSF) that occurs following intraventricular hemorrhage (IVH). An incomplete understanding of this variably progressive condition has hampered the development of new therapies beyond serial neurosurgical interventions. Here, we show a key role for the bidirectional Na-K-Cl cotransporter, NKCC1, in the choroid plexus (ChP) to mitigate PHH. Mimicking IVH with intraventricular blood led to increased CSF [K+] and triggered cytosolic calcium activity in ChP epithelial cells, which was followed by NKCC1 activation. ChP-targeted adeno-associated viral (AAV)-NKCC1 prevented blood-induced ventriculomegaly and led to persistently increased CSF clearance capacity. These data demonstrate that intraventricular blood triggered a trans-choroidal, NKCC1-dependent CSF clearance mechanism. Inactive, phosphodeficient AAV-NKCC1-NT51 failed to mitigate ventriculomegaly. Excessive CSF [K+] fluctuations correlated with permanent shunting outcome in humans following hemorrhagic stroke, suggesting targeted gene therapy as a potential treatment to mitigate intracranial fluid accumulation following hemorrhage.
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Plexo Corióideo , Hidrocefalia , Humanos , Hidrocefalia/terapia , Hemorragia Cerebral/complicações , Hemorragia Cerebral/terapiaRESUMO
The trigeminal sensory innervation of the cranial meninges is thought to serve a nociceptive function and mediate headache pain. However, the activity of meningeal afferents under natural conditions in awake animals remains unexplored. Here, we used two- and three-dimensional two-photon calcium imaging to track the activity of meningeal afferent fibers in awake mice. Surprisingly, a large subset of afferents was activated during non-noxious conditions such as locomotion. We estimated locomotion-related meningeal deformations and found afferents with distinct dynamics and tuning to various levels of meningeal expansion, compression, shearing, and Z-axis motion. Further, these mechanosensitive afferents were often tuned to distinct directions of meningeal expansion or compression. Thus, in addition to their role in headache-related pain, meningeal sensory neurons track the dynamic mechanical state of the meninges under natural conditions.
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Meninges , Neurônios Aferentes , Animais , Camundongos , Neurônios Aferentes/fisiologia , Cefaleia , LocomoçãoRESUMO
For many cancer patients, chemotherapy produces untreatable life-long neurologic effects termed chemotherapy-related cognitive impairment (CRCI). We discovered that the chemotherapy methotrexate (MTX) adversely affects oxidative metabolism of non-cancerous choroid plexus (ChP) cells and the cerebrospinal fluid (CSF). We used a ChP-targeted adeno-associated viral (AAV) vector approach in mice to augment CSF levels of the secreted antioxidant SOD3. AAV-SOD3 gene therapy increased oxidative defense capacity of the CSF and prevented MTX-induced lipid peroxidation in the hippocampus. Furthermore, this gene therapy prevented anxiety and deficits in short-term learning and memory caused by MTX. MTX-induced oxidative damage to cultured human cortical neurons and analyses of CSF samples from MTX-treated lymphoma patients demonstrated that MTX diminishes antioxidant capacity of patient CSF. Collectively, our findings motivate the advancement of ChP- and CSF-targeted anti-oxidative prophylactic measures to relieve CRCI.
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Antioxidantes , Neoplasias , Humanos , Animais , Camundongos , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Plexo Corióideo , Metotrexato/toxicidade , Estresse Oxidativo , Hipocampo , Neoplasias/induzido quimicamenteRESUMO
The choroid plexus (ChP) in each brain ventricle produces cerebrospinal fluid (CSF) and forms the blood-CSF barrier. Here, we construct a single-cell and spatial atlas of each ChP in the developing, adult, and aged mouse brain. We delineate diverse cell types, subtypes, cell states, and expression programs in epithelial and mesenchymal cells across ages and ventricles. In the developing ChP, we predict a common progenitor pool for epithelial and neuronal cells, validated by lineage tracing. Epithelial and fibroblast cells show regionalized expression by ventricle, starting at embryonic stages and persisting with age, with a dramatic transcriptional shift with maturation, and a smaller shift in each aged cell type. With aging, epithelial cells upregulate host-defense programs, and resident macrophages upregulate interleukin-1ß (IL-1ß) signaling genes. Our atlas reveals cellular diversity, architecture and signaling across ventricles during development, maturation, and aging of the ChP-brain barrier.
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Plexo Corióideo/embriologia , Plexo Corióideo/metabolismo , Fatores Etários , Envelhecimento/fisiologia , Animais , Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Encéfalo/fisiologia , Encefalopatias/genética , Encefalopatias/fisiopatologia , Diferenciação Celular/genética , Linhagem da Célula/genética , Plexo Corióideo/fisiologia , Células Epiteliais/metabolismo , Feminino , Masculino , Camundongos/embriologia , Camundongos Endogâmicos C57BL , Transdução de Sinais , Análise de Célula ÚnicaRESUMO
Cerebrospinal fluid (CSF) provides vital support for the brain. Abnormal CSF accumulation, such as hydrocephalus, can negatively affect perinatal neurodevelopment. The mechanisms regulating CSF clearance during the postnatal critical period are unclear. Here, we show that CSF K+, accompanied by water, is cleared through the choroid plexus (ChP) during mouse early postnatal development. We report that, at this developmental stage, the ChP showed increased ATP production and increased expression of ATP-dependent K+ transporters, particularly the Na+, K+, Cl-, and water cotransporter NKCC1. Overexpression of NKCC1 in the ChP resulted in increased CSF K+ clearance, increased cerebral compliance, and reduced circulating CSF in the brain without changes in intracranial pressure in mice. Moreover, ChP-specific NKCC1 overexpression in an obstructive hydrocephalus mouse model resulted in reduced ventriculomegaly. Collectively, our results implicate NKCC1 in regulating CSF K+ clearance through the ChP in the critical period during postnatal neurodevelopment in mice.
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Líquido Cefalorraquidiano/metabolismo , Plexo Corióideo/patologia , Hidrocefalia/patologia , Membro 2 da Família 12 de Carreador de Soluto/metabolismo , Animais , Animais Recém-Nascidos , Plexo Corióideo/diagnóstico por imagem , Plexo Corióideo/crescimento & desenvolvimento , Plexo Corióideo/metabolismo , Dependovirus/genética , Modelos Animais de Doenças , Embrião de Mamíferos , Feminino , Vetores Genéticos/administração & dosagem , Vetores Genéticos/genética , Humanos , Hidrocefalia/congênito , Hidrocefalia/diagnóstico , Hidrocefalia/fisiopatologia , Injeções Intraventriculares , Pressão Intracraniana/fisiologia , Imageamento por Ressonância Magnética , Masculino , Camundongos , Camundongos Transgênicos , Membro 2 da Família 12 de Carreador de Soluto/genéticaRESUMO
The choroid plexus (ChP) regulates brain development by secreting instructive cues and providing a protective brain barrier. Here, we show that polyI:C-mediated maternal immune activation leads to an inflammatory response in the developing embryonic mouse brain that manifests as pro-inflammatory cerebrospinal fluid (CSF) and accumulation of ChP macrophages. Elevation of CSF-CCL2 was sufficient to drive ChP immune cell recruitment, activation, and proliferation. In addition, ChP macrophages abandoned their regular tiling pattern and relocated to the ChP-free margin where they breached the weakened epithelial barrier. We further found that these immune cells entered from the ChP into the brain via anatomically specialized "hotspots" at the distal tips of ChP villi. In vivo two-photon imaging demonstrated that surveillance behaviors in ChP macrophages had already emerged at this early stage of embryogenesis. Thus, the embryonic ChP forms a functional brain barrier that can mount an inflammatory response to external insults.
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Plexo Corióideo/embriologia , Plexo Corióideo/imunologia , Inflamação/patologia , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Proliferação de Células , Líquido Cefalorraquidiano/metabolismo , Quimiocina CCL2/metabolismo , Imageamento Tridimensional , Mediadores da Inflamação/metabolismo , Ativação de Macrófagos , Camundongos Endogâmicos C57BL , Proteínas dos Microfilamentos/metabolismo , Receptores CCR2/metabolismo , Transdução de Sinais , Junções Íntimas/metabolismo , Regulação para CimaRESUMO
The choroid plexus (ChP) epithelium is a source of secreted signaling factors in cerebrospinal fluid (CSF) and a key barrier between blood and brain. Here, we develop imaging tools to interrogate these functions in adult lateral ventricle ChP in whole-mount explants and in awake mice. By imaging epithelial cells in intact ChP explants, we observed calcium activity and secretory events that increased in frequency following delivery of serotonergic agonists. Using chronic two-photon imaging in awake mice, we observed spontaneous subcellular calcium events as well as strong agonist-evoked calcium activation and cytoplasmic secretion into CSF. Three-dimensional imaging of motility and mobility of multiple types of ChP immune cells at baseline and following immune challenge or focal injury revealed a range of surveillance and defensive behaviors. Together, these tools should help illuminate the diverse functions of this understudied body-brain interface.
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Cálcio/metabolismo , Líquido Cefalorraquidiano/imunologia , Líquido Cefalorraquidiano/metabolismo , Plexo Corióideo/imunologia , Plexo Corióideo/metabolismo , Imagem Óptica/métodos , Animais , Plexo Corióideo/efeitos dos fármacos , Epitélio/metabolismo , Camundongos , Agonistas do Receptor de Serotonina/farmacologiaRESUMO
The ability to acquire large-scale recordings of neuronal activity in awake and unrestrained animals is needed to provide new insights into how populations of neurons generate animal behavior. We present an instrument capable of recording intracellular calcium transients from the majority of neurons in the head of a freely behaving Caenorhabditis elegans with cellular resolution while simultaneously recording the animal's position, posture, and locomotion. This instrument provides whole-brain imaging with cellular resolution in an unrestrained and behaving animal. We use spinning-disk confocal microscopy to capture 3D volumetric fluorescent images of neurons expressing the calcium indicator GCaMP6s at 6 head-volumes/s. A suite of three cameras monitor neuronal fluorescence and the animal's position and orientation. Custom software tracks the 3D position of the animal's head in real time and two feedback loops adjust a motorized stage and objective to keep the animal's head within the field of view as the animal roams freely. We observe calcium transients from up to 77 neurons for over 4 min and correlate this activity with the animal's behavior. We characterize noise in the system due to animal motion and show that, across worms, multiple neurons show significant correlations with modes of behavior corresponding to forward, backward, and turning locomotion.
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Comportamento Animal , Caenorhabditis elegans/metabolismo , Cálcio/metabolismo , Imagem Molecular/métodos , Neurônios/metabolismo , AnimaisRESUMO
Understanding how an organism's nervous system transforms sensory input into behavioral outputs requires recording and manipulating its neural activity during unrestrained behavior. Here we present an instrument to simultaneously monitor and manipulate neural activity while observing behavior in a freely moving animal, the nematode Caenorhabditis elegans. Neural activity is recorded optically from cells expressing a calcium indicator, GCaMP3. Neural activity is manipulated optically by illuminating targeted neurons expressing the optogenetic protein Channelrhodopsin. Real-time computer vision software tracks the animal's behavior and identifies the location of targeted neurons in the nematode as it crawls. Patterned illumination from a DMD is used to selectively illuminate subsets of neurons for either calcium imaging or optogenetic stimulation. Real-time computer vision software constantly updates the illumination pattern in response to the worm's movement and thereby allows for independent optical recording or activation of different neurons in the worm as it moves freely. We use the instrument to directly observe the relationship between sensory neuron activation, interneuron dynamics and locomotion in the worm's mechanosensory circuit. We record and compare calcium transients in the backward locomotion command interneurons AVA, in response to optical activation of the anterior mechanosensory neurons ALM, AVM or both.
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Comportamento Animal/fisiologia , Cálcio/metabolismo , Locomoção/fisiologia , Neurônios/metabolismo , Optogenética , Animais , Caenorhabditis elegans , Locomoção/genéticaRESUMO
Precision position-sensing is required for many microscopy techniques. One promising method, back-scattered detection (BSD), is incredibly sensitive, allowing for position measurements at the level of tens of picometers in three dimensions. In BSD the position of a micron-sized bead is measured by back-scattering a focused laser beam off the bead and imaging the resulting interference pattern onto a detector. Since the detection system geometry is confined to one side of the objective, the technique is compatible with platforms that have restricted optical access (e.g. magnetic tweezers, atomic force microscopy, and microfluidics). However, general adoption of BSD may be limited according to a recent theory [Volpe et al., J. Appl. Phys. 102, 084701, 2007] that predicts diminished signals under certain conditions. We directly measured the BSD response while varying the experimental conditions, including bead radius, numerical aperture, and relative index. Contrary to the proposed theory, we find that all experimental conditions tested produced a viable signal for atomic-scale measurements.