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Nature Aging Aug 2022Peripheral inflammation triggers a transient, well-defined set of behavioral changes known as sickness behavior, but the mechanisms by which inflammatory signals...
Peripheral inflammation triggers a transient, well-defined set of behavioral changes known as sickness behavior, but the mechanisms by which inflammatory signals originating in the periphery alter activity in the brain remain obscure. Emerging evidence has established meningeal lymphatic vasculature as an important interface between the central nervous system (CNS) and the immune system, responsible for facilitating brain solute clearance and perfusion by cerebrospinal fluid (CSF). Here, we demonstrate that meningeal lymphatics both assist microglial activation and support the behavioral response to peripheral inflammation. Ablation of meningeal lymphatics results in a heightened behavioral response to IL-1β-induced inflammation and a dampened transcriptional and morphological microglial phenotype. Moreover, our findings support a role for microglia in tempering the severity of sickness behavior with specific relevance to aging-related meningeal lymphatic dysfunction. Transcriptional profiling of brain myeloid cells shed light on the impact of meningeal lymphatic dysfunction on microglial activation. Furthermore, we demonstrate that experimental enhancement of meningeal lymphatic function in aged mice is sufficient to reduce the severity of exploratory abnormalities but not pleasurable consummatory behavior. Finally, we identify dysregulated genes and biological pathways, common to both experimental meningeal lymphatic ablation and aging, in microglia responding to peripheral inflammation that may result from age-related meningeal lymphatic dysfunction.
Topics: Mice; Animals; Microglia; Meninges; Central Nervous System; Lymphatic Vessels; Inflammation
PubMed: 37065770
DOI: 10.1038/s43587-022-00268-y -
European Journal of Medical Research Aug 2023The clinical features of aseptic meningitis associated with amoxicillin are unknown. The main objective of this study was to investigate the clinical characteristics of...
OBJECTIVES
The clinical features of aseptic meningitis associated with amoxicillin are unknown. The main objective of this study was to investigate the clinical characteristics of amoxicillin-induced aseptic meningitis (AIAM) and provide a reference for clinical diagnosis and treatment.
METHODS
AIAM-related studies were collected by searching the relevant databases from inception to October 31, 2022.
RESULTS
AIAM usually occurred 3 h to 7 days after amoxicillin administration in 13 males and 9 females. Twenty-one patients (95.5%) had recurrent AIAM with a total of 62 episodes. Fever (19 cases, 86.4%) and headache (18 cases, 81.8%) were the most common symptoms. Typical cerebrospinal fluid (CSF) findings were leukocytosis (100%) with lymphocytic predominance (14 cases, 63.6%), elevated protein (20 cases, 90.1%), normal glucose (21 cases, 95.5%) and negative culture (21 cases, 100%). Brain magnetic resonance imaging showed mild meningeal enhancement in one patient. The symptoms resolved mainly within 1-4 days after drug discontinuation in all patients.
CONCLUSION
Clinical attention should be given to the adverse effects of AIAM. The medication history of patients with suspected meningitis should be investigated to avoid unnecessary examination and antibiotic treatment.
Topics: Humans; Meningitis, Aseptic; Male; Female; Adult; Middle Aged; Aged; Aged, 80 and over; Amoxicillin; Case Reports as Topic
PubMed: 37635233
DOI: 10.1186/s40001-023-01251-y -
Nature Communications Jun 2020Extravasated erythrocytes in cerebrospinal fluid (CSF) critically contribute to the pathogenesis of subarachnoid hemorrhage (SAH). Meningeal lymphatics have been...
Extravasated erythrocytes in cerebrospinal fluid (CSF) critically contribute to the pathogenesis of subarachnoid hemorrhage (SAH). Meningeal lymphatics have been reported to drain macromolecules and immune cells from CSF into cervical lymph nodes (CLNs). However, whether meningeal lymphatics are involved in clearing extravasated erythrocytes in CSF after SAH remains unclear. Here we show that a markedly higher number of erythrocytes are accumulated in the lymphatics of CLNs and meningeal lymphatics after SAH. When the meningeal lymphatics are depleted in a mouse model of SAH, the degree of erythrocyte aggregation in CLNs is significantly lower, while the associated neuroinflammation and the neurologic deficits are dramatically exacerbated. In addition, during SAH lymph flow is increased but without significant lymphangiogenesis and lymphangiectasia. Taken together, this work demonstrates that the meningeal lymphatics drain extravasated erythrocytes from CSF into CLNs after SAH, while suggesting that modulating this draining may offer therapeutic approaches to alleviate SAH severity.
Topics: Animals; Brain Injuries; Erythrocytes; Lymph Nodes; Lymphangiogenesis; Lymphatic System; Lymphatic Vessels; Male; Meninges; Meningitis; Mice; Mice, Inbred C57BL; Models, Animal; Neck; Subarachnoid Hemorrhage; Vascular Endothelial Growth Factor Receptor-3
PubMed: 32572022
DOI: 10.1038/s41467-020-16851-z -
Arquivos de Neuro-psiquiatria Nov 2022Chronic meningitis (CM) is characterized by neurological symptoms associated with the evidence of cerebrospinal fluid pleocytosis lasting > 4 weeks. Studies on the... (Review)
Review
BACKGROUND
Chronic meningitis (CM) is characterized by neurological symptoms associated with the evidence of cerebrospinal fluid pleocytosis lasting > 4 weeks. Studies on the management of CM in Brazil are scarce.
OBJECTIVE
To critically review the literature on CM and propose a rational approach in the Brazilian scenario.
METHODS
Narrative literature review discussing the epidemiology, clinical evaluation, basic and advanced diagnostic testing, and empirical and targeted therapy for the most relevant causes of CM. The present review was contextualized with the local experience of the authors. In addition, we propose an algorithm for the management of CM in Brazil.
RESULTS
In Brazil, tuberculosis and cryptococcosis are endemic and should always be considered in CM patients. In addition to these diseases, neurosyphilis and other endemic conditions should be included in the differential diagnosis, including neurocysticercosis, Baggio-Yoshinari syndrome, and endemic mycosis. After infectious etiologies, meningeal carcinomatosis and autoimmune diseases should be considered. Unbiased and targeted methods should be used based on availability and clinical and epidemiological data.
CONCLUSION
We propose a rational approach to CM in Brazil, considering the epidemiological scenario, systematizing the etiological investigation, and evaluating the timely use of empirical therapies.
Topics: Humans; Brazil; Meningitis; Syndrome; Neurocysticercosis; Neurosyphilis
PubMed: 36577417
DOI: 10.1055/s-0042-1758645 -
Developmental Cell Apr 2023The arachnoid barrier, a component of the blood-cerebrospinal fluid barrier (B-CSFB) in the meninges, is composed of epithelial-like, tight-junction-expressing cells....
The arachnoid barrier, a component of the blood-cerebrospinal fluid barrier (B-CSFB) in the meninges, is composed of epithelial-like, tight-junction-expressing cells. Unlike other central nervous system (CNS) barriers, its' developmental mechanisms and timing are largely unknown. Here, we show that mouse arachnoid barrier cell specification requires the repression of Wnt-β-catenin signaling and that constitutively active β-catenin can prevent its formation. We also show that the arachnoid barrier is functional prenatally and, in its absence, a small molecular weight tracer and the bacterium group B Streptococcus can cross into the CNS following peripheral injection. Acquisition of barrier properties prenatally coincides with the junctional localization of Claudin 11, and increased E-cadherin and maturation continues after birth, where postnatal expansion is marked by proliferation and re-organization of junctional domains. This work identifies fundamental mechanisms that drive arachnoid barrier formation, highlights arachnoid barrier fetal functions, and provides novel tools for future studies on CNS barrier development.
Topics: Mice; Animals; beta Catenin; Meninges; Arachnoid; Blood-Brain Barrier; Central Nervous System; Tight Junctions
PubMed: 36996816
DOI: 10.1016/j.devcel.2023.03.005 -
PloS One 2021Meningitis is a medical emergency with permanent disabilities and high mortality worldwide. We aimed to determine causative microorganisms and potential markers for...
OBJECTIVES
Meningitis is a medical emergency with permanent disabilities and high mortality worldwide. We aimed to determine causative microorganisms and potential markers for differentiation between bacterial and viral meningitis.
METHODOLOGY
Adult patients with acute meningitis were subjected to lumber puncture. Cerebrospinal fluid (CSF) microorganisms were identified using Real-time PCR. PCT and CRP levels, peripheral and CSF-leucocyte count, CSF-protein and CSF-glucose levels were assessed.
RESULTS
Out of 80 patients, infectious meningitis was confirmed in 75 cases; 38 cases were bacterial meningitis, 34 cases were viral meningitis and three cases were mixed infection. Higher PCT, peripheral and CSF-leukocytosis, higher CSF-protein and lower CSF-glucose levels were more significant in bacterial than viral meningitis patients. Neisseria meningitides was the most frequent bacteria and varicella-zoster virus was the most common virus. Using ROC analyses, serum PCT and CSF-parameters can discriminate bacterial from viral meningitis. Combined ROC analyses of PCT and CSF-protein significantly improved the effectiveness in predicting bacterial meningitis (AUC of 0.998, 100%sensitivity and 97.1%specificity) than each parameter alone (AUC of 0.951 for PCT and 0.996 for CSF-protein).
CONCLUSION
CSF-protein and serum PCT are considered as potential markers for differentiating bacterial from viral meningitis and their combination improved their predictive accuracy to bacterial meningitis.
Topics: Adult; Biomarkers; Diagnosis, Differential; Female; Humans; Male; Meningitis, Bacterial; Meningitis, Viral
PubMed: 34115780
DOI: 10.1371/journal.pone.0251518 -
BMC Neurology Jun 2021The internet has made significant contributions towards health education. Analyzing the pattern of online behavior regarding meningitis and vaccinations may be...
BACKGROUND
The internet has made significant contributions towards health education. Analyzing the pattern of online behavior regarding meningitis and vaccinations may be worthwhile. It is hypothesized that the online search patterns in meningitis are correlated with its number of cases and the search patterns of its related vaccines.
METHODS
This was an infodemiological study that determined the relationship among online search interest in meningitis, its worldwide number of cases and its associated vaccines. Using Google Trends™ Search Volume Indices (SVIs), we evaluated the search queries "meningitis," "pneumococcal vaccine," "BCG vaccine," "meningococcal vaccine" and "influenza vaccine" in January 2021, covering January 2008 to December 2020. Spearman rank correlation was used to determine correlations between these queries.
RESULTS
The worldwide search interest in meningitis from 2008 to 2020 showed an average SVI of 46 ± 8.8. The most searched topics were symptoms, vaccines, and infectious agents with SVIs of 100, 52, and 39, respectively. The top three countries with the highest search interest were Ghana, Kazakhstan, and Kenya. There were weak, but statistically significant correlations between meningitis and the BCG (ρ = 0.369, p < 0.001) and meningococcal (ρ = 0.183, p < 0.05) vaccines. There were no statistically significant associations between the number of cases, influenza vaccine, and pneumococcal vaccine.
CONCLUSION
The relationships among the Google SVIs for meningitis and its related vaccines and number of cases data were inconsistent and remained unclear. Future infodemiological studies may expand their scopes to social media, semantics, and big data for more robust conclusions.
Topics: BCG Vaccine; Databases, Factual; Developed Countries; Developing Countries; Global Burden of Disease; Humans; Information Services; Male; Meningitis; Meningococcal Vaccines
PubMed: 34162337
DOI: 10.1186/s12883-021-02258-w -
The Journal of Neuroscience : the... Aug 2023Cortical spreading depolarization (CSD) is a key pathophysiological event that underlies visual and sensory auras in migraine. CSD is also thought to drive the headache...
Cortical spreading depolarization (CSD) is a key pathophysiological event that underlies visual and sensory auras in migraine. CSD is also thought to drive the headache phase in migraine by promoting the activation and mechanical sensitization of trigeminal primary afferent nociceptive neurons that innervate the cranial meninges. The factors underlying meningeal nociception in the wake of CSD remain poorly understood but potentially involve the parenchymal release of algesic mediators and damage-associated molecular patterns, particularly ATP. Here, we explored the role of ATP-P2X purinergic receptor signaling in mediating CSD-evoked meningeal afferent activation and mechanical sensitization. Male rats were subjected to a single CSD episode. , extracellular single-unit recording was used to measure meningeal afferent ongoing activity changes. Quantitative mechanical stimuli using a servomotor force-controlled stimulator assessed changes in the afferent's mechanosensitivity. Manipulation of meningeal P2X receptors was achieved via local administration of pharmacological agents. Broad-spectrum P2X receptor inhibition, selective blockade of the P2X7 receptor, and its related Pannexin 1 channel suppressed CSD-evoked afferent mechanical sensitization but did not affect the accompanying afferent activation response. Surprisingly, inhibition of the pronociceptive P2X2/3 receptor did not affect the activation or sensitization of meningeal afferents post-CSD. P2X7 signaling underlying afferent mechanosensitization was localized to the meninges and did not affect CSD susceptibility. We propose that meningeal P2X7 and Pannexin 1 signaling, potentially in meningeal macrophages or neutrophils, mediates the mechanical sensitization of meningeal afferents, which contributes to migraine pain by exacerbating the headache during normally innocuous physical activities. Activation and sensitization of meningeal afferents play a key role in migraine headache, but the underlying mechanisms remain unclear. Here, using a rat model of migraine with aura involving cortical spreading depolarization (CSD), we demonstrate that meningeal purinergic P2X7 signaling and its related Pannexin 1 pore, but not nociceptive P2X2/3 receptors, mediate prolonged meningeal afferent sensitization. Additionally, we show that meningeal P2X signaling does not contribute to the increased afferent ongoing activity in the wake of CSD. Our finding points to meningeal P2X7 signaling as a critical mechanism underlying meningeal nociception in migraine, the presence of distinct mechanisms underlying the activation and sensitization of meningeal afferents in migraine, and highlight the need to target both processes for effective migraine therapy.
Topics: Rats; Male; Animals; Nociceptors; Migraine Disorders; Meninges; Headache; Adenosine Triphosphate
PubMed: 37487740
DOI: 10.1523/JNEUROSCI.0368-23.2023 -
Molecules (Basel, Switzerland) Jan 2021The blood-brain barrier (BBB) is the protective sheath around the brain that protects the sensitive microenvironments of the brain. However, certain pathogens, viruses,... (Review)
Review
The blood-brain barrier (BBB) is the protective sheath around the brain that protects the sensitive microenvironments of the brain. However, certain pathogens, viruses, and bacteria disrupt the endothelial barrier and cause infection and hence inflammation in meninges. Macromolecular therapeutics are unable to cross the tight junctions, thereby limiting their bioavailability in the brain. Recently, nanotechnology has brought a revolution in the field of drug delivery in brain infections. The nanostructures have high targeting accuracy and specificity to the receptors in the case of active targeting, which have made them the ideal cargoes to permeate across the BBB. In addition, nanomaterials with biomimetic functions have been introduced to efficiently cross the BBB to be engulfed by the pathogens. This review focuses on the nanotechnology-based drug delivery approaches for exploration in brain infections, including meningitis. Viruses, bacteria, fungi, or, rarely, protozoa or parasites may be the cause of brain infections. Moreover, inflammation of the meninges, called meningitis, is presently diagnosed using laboratory and imaging tests. Despite attempts to improve diagnostic instruments for brain infections and meningitis, due to its complicated and multidimensional nature and lack of successful diagnosis, meningitis appears almost untreatable. Potential for overcoming the difficulties and limitations related to conventional diagnostics has been shown by nanoparticles (NPs). Nanomedicine now offers new methods and perspectives to improve our knowledge of meningitis and can potentially give meningitis patients new hope. Here, we review traditional diagnosis tools and key nanoparticles (Au-NPs, graphene, carbon nanotubes (CNTs), QDs, etc.) for early diagnosis of brain infections and meningitis.
Topics: Brain Diseases; Drug Carriers; Drug Delivery Systems; Graphite; Humans; Meningitis; Nanomedicine; Nanoparticles; Nanotechnology
PubMed: 33401658
DOI: 10.3390/molecules26010186 -
Nature Communications Sep 2023Meninges cover the surface of the brain and spinal cord and contribute to protection and immune surveillance of the central nervous system (CNS). How the meningeal...
Meninges cover the surface of the brain and spinal cord and contribute to protection and immune surveillance of the central nervous system (CNS). How the meningeal layers establish CNS compartments with different accessibility to immune cells and immune mediators is, however, not well understood. Here, using 2-photon imaging in female transgenic reporter mice, we describe VE-cadherin at intercellular junctions of arachnoid and pia mater cells that form the leptomeninges and border the subarachnoid space (SAS) filled with cerebrospinal fluid (CSF). VE-cadherin expression also marked a layer of Prox1 cells located within the arachnoid beneath and separate from E-cadherin arachnoid barrier cells. In vivo imaging of the spinal cord and brain in female VE-cadherin-GFP reporter mice allowed for direct observation of accessibility of CSF derived tracers and T cells into the SAS bordered by the arachnoid and pia mater during health and neuroinflammation, and detection of volume changes of the SAS during CNS pathology. Together, the findings identified VE-cadherin as an informative landmark for in vivo imaging of the leptomeninges that can be used to visualize the borders of the SAS and thus potential barrier properties of the leptomeninges in controlling access of immune mediators and immune cells into the CNS during health and neuroinflammation.
Topics: Female; Animals; Mice; Pia Mater; Neuroinflammatory Diseases; Central Nervous System; Arachnoid; Cadherins; Inflammation; Mice, Transgenic
PubMed: 37730744
DOI: 10.1038/s41467-023-41580-4