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Science (New York, N.Y.) Jul 2021The meninges are a membranous structure enveloping the central nervous system (CNS) that host a rich repertoire of immune cells mediating CNS immune surveillance. Here,...
The meninges are a membranous structure enveloping the central nervous system (CNS) that host a rich repertoire of immune cells mediating CNS immune surveillance. Here, we report that the mouse meninges contain a pool of monocytes and neutrophils supplied not from the blood but by adjacent skull and vertebral bone marrow. Under pathological conditions, including spinal cord injury and neuroinflammation, CNS-infiltrating myeloid cells can originate from brain borders and display transcriptional signatures distinct from their blood-derived counterparts. Thus, CNS borders are populated by myeloid cells from adjacent bone marrow niches, strategically placed to supply innate immune cells under homeostatic and pathological conditions. These findings call for a reinterpretation of immune-cell infiltration into the CNS during injury and autoimmunity and may inform future therapeutic approaches that harness meningeal immune cells.
Topics: Animals; Bone Marrow; Bone Marrow Cells; Brain; Cell Movement; Central Nervous System; Central Nervous System Diseases; Dura Mater; Encephalomyelitis, Autoimmune, Experimental; Homeostasis; Meninges; Mice; Monocytes; Myeloid Cells; Neutrophils; Skull; Spinal Cord; Spinal Cord Injuries; Spine
PubMed: 34083447
DOI: 10.1126/science.abf7844 -
Revue Neurologique 2019Tuberculous meningitis (TBM) is the most lethal and disabling form of tuberculosis. In 2017, approximately 10 million people developed TB worldwide, of whom more than... (Review)
Review
Tuberculous meningitis (TBM) is the most lethal and disabling form of tuberculosis. In 2017, approximately 10 million people developed TB worldwide, of whom more than 100,000 new cases of TBM are estimated to occur per year. In patients who are co-infected with HIV-1, TBM has a mortality approaching 50%. Diagnosis of TBM is often delayed by the insensitive and lengthy culture technique required for disease confirmation. GeneXpert represents the most significant advance in TBM diagnostics over the past decade, but it lacks sensitivity and cannot be used to rule out the diagnosis. Higher volume of cerebrospinal fluid (CSF) seems to be interesting to improve the diagnosis performances. New rapid and accurate diagnostic tools are necessary. Better advances have been made concerning the anti-tuberculosis chemotherapy of TBM, with the publication of clinical trials and pharmacokinetic studies exploring the use of higher rifampicin doses and fluoroquinolones. The rise of drug-resistant TBM is another challenge for management because TBM caused by multidrug resistant organisms results in death or severe disability in almost all sufferers.
Topics: Humans; Tuberculosis, Meningeal
PubMed: 31383464
DOI: 10.1016/j.neurol.2019.07.007 -
Immunity Nov 2022The surface of the central nervous system (CNS) is protected by the meninges, which contain a dense network of meningeal macrophages (MMs). Here, we examined the role of...
The surface of the central nervous system (CNS) is protected by the meninges, which contain a dense network of meningeal macrophages (MMs). Here, we examined the role of tissue-resident MM in viral infection. MHC-II MM were abundant neonatally, whereas MHC-II MM appeared over time. These barrier macrophages differentially responded to in vivo peripheral challenges such as LPS, SARS-CoV-2, and lymphocytic choriomeningitis virus (LCMV). Peripheral LCMV infection, which was asymptomatic, led to a transient infection and activation of the meninges. Mice lacking macrophages but conserving brain microglia, or mice bearing macrophage-specific deletion of Stat1 or Ifnar, exhibited extensive viral spread into the CNS. Transcranial pharmacological depletion strategies targeting MM locally resulted in several areas of the meninges becoming infected and fatal meningitis. Low numbers of MHC-II MM, which is seen upon LPS challenge or in neonates, corelated with higher viral load upon infection. Thus, MMs protect against viral infection and may present targets for therapeutic manipulation.
Topics: Animals; Mice; Lipopolysaccharides; Mice, Inbred C57BL; SARS-CoV-2; COVID-19; Lymphocytic Choriomeningitis; Lymphocytic choriomeningitis virus; Macrophages; Meninges
PubMed: 36323311
DOI: 10.1016/j.immuni.2022.10.005 -
Arquivos de Neuro-psiquiatria Dec 2020Hypertrophic pachymeningitis (HP) is a non-usual manifestation of rheumatologic, infectious, and neoplastic diseases. Etiological diagnosis is a challenge, but when made...
IMPORTANCE
Hypertrophic pachymeningitis (HP) is a non-usual manifestation of rheumatologic, infectious, and neoplastic diseases. Etiological diagnosis is a challenge, but when made promptly it creates a window of opportunity for treatment, with the possibility of a total reversal of symptoms.
OBSERVATIONS
HP is an inflammatory process of the dura mater that can occur as a manifestation of sarcoidosis, granulomatosis with polyangiitis, and IgG4-related disease. The HP case evaluation is extensive and includes central nervous system imaging, cerebrospinal fluid analysis, serology, rheumatologic tests, and systemic survey for other manifestations sites. After systemic investigation, meningeal biopsy might be necessary. Etiology guides HP treatment, and autoimmune disorders are treated with corticosteroids alone or associated with an immunosuppressor.
CONCLUSION
HP is a manifestation of several diseases, and a precise etiological diagnosis is crucial because of the difference among treatments. An extensive investigation of patients with HP helps early diagnosis and correct treatment.
Topics: Adrenal Cortex Hormones; Dura Mater; Humans; Hypertrophy; Magnetic Resonance Imaging; Meningitis
PubMed: 33295420
DOI: 10.1590/0004-282X20200073 -
Cellular & Molecular Immunology Nov 2023Brain macrophages include microglia in the parenchyma, border-associated macrophages in the meningeal-choroid plexus-perivascular space, and monocyte-derived macrophages... (Review)
Review
Brain macrophages include microglia in the parenchyma, border-associated macrophages in the meningeal-choroid plexus-perivascular space, and monocyte-derived macrophages that infiltrate the brain under various disease conditions. The vast heterogeneity of these cells has been elucidated over the last decade using revolutionary multiomics technologies. As such, we can now start to define these various macrophage populations according to their ontogeny and their diverse functional programs during brain development, homeostasis and disease pathogenesis. In this review, we first outline the critical roles played by brain macrophages during development and healthy aging. We then discuss how brain macrophages might undergo reprogramming and contribute to neurodegenerative disorders, autoimmune diseases, and glioma. Finally, we speculate about the most recent and ongoing discoveries that are prompting translational attempts to leverage brain macrophages as prognostic markers or therapeutic targets for diseases that affect the brain.
Topics: Humans; Macrophages; Microglia; Brain; Meninges; Autoimmune Diseases
PubMed: 37365324
DOI: 10.1038/s41423-023-01053-6 -
Science (New York, N.Y.) Jul 2021The meninges contain adaptive immune cells that provide immunosurveillance of the central nervous system (CNS). These cells are thought to derive from the systemic...
The meninges contain adaptive immune cells that provide immunosurveillance of the central nervous system (CNS). These cells are thought to derive from the systemic circulation. Through single-cell analyses, confocal imaging, bone marrow chimeras, and parabiosis experiments, we show that meningeal B cells derive locally from the calvaria, which harbors a bone marrow niche for hematopoiesis. B cells reach the meninges from the calvaria through specialized vascular connections. This calvarial-meningeal path of B cell development may provide the CNS with a constant supply of B cells educated by CNS antigens. Conversely, we show that a subset of antigen-experienced B cells that populate the meninges in aging mice are blood-borne. These results identify a private source for meningeal B cells, which may help maintain immune privilege within the CNS.
Topics: Aging; Animals; B-Lymphocyte Subsets; B-Lymphocytes; Bone Marrow Cells; Cell Movement; Central Nervous System; Dura Mater; Fibroblasts; Homeostasis; Immune Privilege; Lymphopoiesis; Meninges; Mice; Plasma Cells; Single-Cell Analysis; Skull
PubMed: 34083450
DOI: 10.1126/science.abf9277 -
Neuron Dec 2023Leptomeninges, consisting of the pia mater and arachnoid, form a connective tissue investment and barrier enclosure of the brain. The exact nature of leptomeningeal...
Leptomeninges, consisting of the pia mater and arachnoid, form a connective tissue investment and barrier enclosure of the brain. The exact nature of leptomeningeal cells has long been debated. In this study, we identify five molecularly distinct fibroblast-like transcriptomes in cerebral leptomeninges; link them to anatomically distinct cell types of the pia, inner arachnoid, outer arachnoid barrier, and dural border layer; and contrast them to a sixth fibroblast-like transcriptome present in the choroid plexus and median eminence. Newly identified transcriptional markers enabled molecular characterization of cell types responsible for adherence of arachnoid layers to one another and for the arachnoid barrier. These markers also proved useful in identifying the molecular features of leptomeningeal development, injury, and repair that were preserved or changed after traumatic brain injury. Together, the findings highlight the value of identifying fibroblast transcriptional subsets and their cellular locations toward advancing the understanding of leptomeningeal physiology and pathology.
Topics: Mice; Animals; Meninges; Arachnoid; Pia Mater; Choroid Plexus; Brain
PubMed: 37776854
DOI: 10.1016/j.neuron.2023.09.002 -
Neonatology 2021The diagnosis of neonatal meningitis often rests on microscopic and biochemical findings in the cerebrospinal fluid (CSF). There is ongoing uncertainty about age-related...
BACKGROUND
The diagnosis of neonatal meningitis often rests on microscopic and biochemical findings in the cerebrospinal fluid (CSF). There is ongoing uncertainty about age-related normal values for CSF findings in neonates, and many previous studies have included infants in whom antibiotics were administered before lumbar puncture or in whom viral meningitis was not excluded.
METHODS
A systematic search was done using MEDLINE and EMBASE to identify original studies which investigated CSF normal values in either healthy neonates or febrile neonates in whom bacterial and viral meningitis were reliably excluded.
RESULTS
We identified seven studies investigating 270 term and 96 preterm neonates. There were minimal differences between preterm and term neonates in the CSF white blood cell (WBC) count and glucose concentration. In contrast, the CSF neutrophil count and protein concentration were influenced by gestational and chronological age. In the four studies that reported individual patient data, in 95% of cases the CSF WBC count was <12 cells/μL in preterm and <10 cells/μL in term neonates, the neutrophil count was <16 and 8 cells/μL, and the protein concentration was <210 and 110 mg/dL, respectively.
CONCLUSION
The normal range for CSF parameters in neonates is different to that in older infants, and some parameters are influenced by gestational and chronological age. CSF parameters alone are not sufficiently reliable to exclude meningitis.
Topics: Aged; Humans; Infant; Infant, Newborn; Infant, Newborn, Diseases; Leukocyte Count; Meningitis; Reference Values; Retrospective Studies; Spinal Puncture
PubMed: 34818234
DOI: 10.1159/000517630 -
Radiographics : a Review Publication of... Aug 2023Meningeal lesions can be caused by various conditions and pose diagnostic challenges. The authors review the anatomy of the meninges in the brain and spinal cord to...
Meningeal lesions can be caused by various conditions and pose diagnostic challenges. The authors review the anatomy of the meninges in the brain and spinal cord to provide a better understanding of the localization and extension of these diseases and summarize the clinical and imaging features of various conditions that cause dural and/or leptomeningeal enhancing lesions. These conditions include infectious meningitis (bacterial, tuberculous, viral, and fungal), autoimmune diseases (vasculitis, connective tissue diseases, autoimmune meningoencephalitis, Vogt-Koyanagi-Harada disease, neuro-Behçet syndrome, Susac syndrome, and sarcoidosis), primary and secondary tumors (meningioma, diffuse leptomeningeal glioneuronal tumor, melanocytic tumors, and lymphoma), tumorlike diseases (histiocytosis and immunoglobulin G4-related diseases), medication-induced diseases (immune-related adverse effects and posterior reversible encephalopathy syndrome), and other conditions (spontaneous intracranial hypotension, amyloidosis, and moyamoya disease). Although meningeal lesions may manifest with nonspecific imaging findings, correct diagnosis is important because the treatment strategy varies among these diseases. RSNA, 2023 and Quiz questions for this article are available through the Online Learning Center.
Topics: Humans; Posterior Leukoencephalopathy Syndrome; Meninges; Meningitis; Neuroimaging; Sarcoidosis; Meningeal Neoplasms; Magnetic Resonance Imaging
PubMed: 37535461
DOI: 10.1148/rg.230039 -
Nature Communications Sep 2020Traumatic brain injury (TBI) is a leading global cause of death and disability. Here we demonstrate in an experimental mouse model of TBI that mild forms of brain trauma...
Traumatic brain injury (TBI) is a leading global cause of death and disability. Here we demonstrate in an experimental mouse model of TBI that mild forms of brain trauma cause severe deficits in meningeal lymphatic drainage that begin within hours and last out to at least one month post-injury. To investigate a mechanism underlying impaired lymphatic function in TBI, we examined how increased intracranial pressure (ICP) influences the meningeal lymphatics. We demonstrate that increased ICP can contribute to meningeal lymphatic dysfunction. Moreover, we show that pre-existing lymphatic dysfunction before TBI leads to increased neuroinflammation and negative cognitive outcomes. Finally, we report that rejuvenation of meningeal lymphatic drainage function in aged mice can ameliorate TBI-induced gliosis. These findings provide insights into both the causes and consequences of meningeal lymphatic dysfunction in TBI and suggest that therapeutics targeting the meningeal lymphatic system may offer strategies to treat TBI.
Topics: Animals; Brain Injuries; Dependovirus; Disease Models, Animal; Female; Genetic Vectors; Gliosis; Glymphatic System; Humans; Male; Meninges; Mice; Vascular Endothelial Growth Factor C
PubMed: 32913280
DOI: 10.1038/s41467-020-18113-4