The Serendipity of Viral Trans-Neuronal Specificity: More Than Meets the Eye

One Step ◽

Neuronal Specificity ◽

The Brain ◽

Neuroscience Community

Trans-neuronal viruses are frequently used as neuroanatomical tools for mapping neuronal circuits. Specifically, recombinant one-step rabies viruses (RABV) have been instrumental in the widespread application of viral circuit mapping, as these viruses have enabled labs to map the direct inputs onto defined cell populations. Within the neuroscience community, it is widely believed that RABV spreads directly between neurons via synaptic connections, a hypothesis based principally on two observations. First, the virus labels neurons in a pattern consistent with known anatomical connectivity. Second, few glial cells appear to be infected following RABV injections, despite the fact that glial cells are abundant in the brain. However, there is no direct evidence that RABV can actually be transmitted through synaptic connections. Here we review the immunosubversive mechanisms that are critical to RABV’s success for infiltration of the central nervous system (CNS). These include interfering with and ultimately killing migratory T cells while maintaining levels of interferon (IFN) signaling in the brain parenchyma. Finally, we critically evaluate studies that support or are against synaptically-restricted RABV transmission and the implications of viral-host immune responses for RABV transmission in the brain.

The Microbiota–Gut–Brain Axis and Alzheimer Disease. From Dysbiosis to Neurodegeneration: Focus on the Central Nervous System Glial Cells

Journal of Clinical Medicine ◽

10.3390/jcm10112358 ◽

2021 ◽

Vol 10 (11) ◽

pp. 2358

Author(s):

Maria Grazia Giovannini ◽

Daniele Lana ◽

Chiara Traini ◽

Maria Giuliana Vannucchi

Keyword(s):

Alzheimer Disease ◽

Glial Cells ◽

Cell Types ◽

The Past ◽

Diseased State ◽

The Brain ◽

Alzheimer Disease Pathogenesis ◽

Brain Homeostasis

The microbiota–gut system can be thought of as a single unit that interacts with the brain via the “two-way” microbiota–gut–brain axis. Through this axis, a constant interplay mediated by the several products originating from the microbiota guarantees the physiological development and shaping of the gut and the brain. In the present review will be described the modalities through which the microbiota and gut control each other, and the main microbiota products conditioning both local and brain homeostasis. Much evidence has accumulated over the past decade in favor of a significant association between dysbiosis, neuroinflammation and neurodegeneration. Presently, the pathogenetic mechanisms triggered by molecules produced by the altered microbiota, also responsible for the onset and evolution of Alzheimer disease, will be described. Our attention will be focused on the role of astrocytes and microglia. Numerous studies have progressively demonstrated how these glial cells are important to ensure an adequate environment for neuronal activity in healthy conditions. Furthermore, it is becoming evident how both cell types can mediate the onset of neuroinflammation and lead to neurodegeneration when subjected to pathological stimuli. Based on this information, the role of the major microbiota products in shifting the activation profiles of astrocytes and microglia from a healthy to a diseased state will be discussed, focusing on Alzheimer disease pathogenesis.

Vascular Dysfunction Induced by Mercury Exposure

International Journal of Molecular Sciences ◽

10.3390/ijms20102435 ◽

2019 ◽

Vol 20 (10) ◽

pp. 2435 ◽

Cited By ~ 4

Author(s):

Tetsuya Takahashi ◽

Takayoshi Shimohata

Keyword(s):

Oxidative Stress ◽

Vascular Dysfunction ◽

Brain Parenchyma ◽

Transport Systems ◽

Mehg Exposure ◽

In Vivo Models ◽

Methylmercury (MeHg) causes severe damage to the central nervous system, and there is increasing evidence of the association between MeHg exposure and vascular dysfunction, hemorrhage, and edema in the brain, but not in other organs of patients with acute MeHg intoxication. These observations suggest that MeHg possibly causes blood–brain barrier (BBB) damage. MeHg penetrates the BBB into the brain parenchyma via active transport systems, mainly the l-type amino acid transporter 1, on endothelial cell membranes. Recently, exposure to mercury has significantly increased. Numerous reports suggest that long-term low-level MeHg exposure can impair endothelial function and increase the risks of cardiovascular disease. The most widely reported mechanism of MeHg toxicity is oxidative stress and related pathways, such as neuroinflammation. BBB dysfunction has been suggested by both in vitro and in vivo models of MeHg intoxication. Therapy targeted at both maintaining the BBB and suppressing oxidative stress may represent a promising therapeutic strategy for MeHg intoxication. This paper reviews studies on the relationship between MeHg exposure and vascular dysfunction, with a special emphasis on the BBB.

Pathological potential of astroglia

Physiological Research ◽

10.33549/physiolres.931604 ◽

2008 ◽

pp. S101-S110

Author(s):

A Chvátal ◽

M Anděrová ◽

H Neprašová ◽

I Prajerová ◽

J Benešová ◽

...

Keyword(s):

Glial Cells ◽

Brain Parenchyma ◽

Brain Diseases ◽

Brain Pathology ◽

Pathological Conditions ◽

Recent Developments ◽

Neurological Defect ◽

Del Rio ◽

The Brain ◽

Brain Homeostasis

The pathological potential of glial cells was recognized already by Rudolf Virchow, Santiago Ramon y Cajal and Pio Del Rio-Ortega. Many functions and roles performed by astroglia in the healthy brain determine their involvement in brain diseases; as indeed any kind of brain insult does affect astrocytes, and their performance in pathological conditions, to a very large extent, determines the survival of the brain parenchyma, the degree of damage and neurological defect. Astrocytes being in general responsible for overall brain homeostasis are involved in virtually every form of brain pathology. Here we provide an overview of recent developments in identifying the role and mechanisms of the pathological potential of astroglia.

Fatal Parasitic Meningoencephalomyelitis Caused By Halicephalobus deletrix: A Case Report and Review of the Literature

Archives of Pathology & Laboratory Medicine ◽

10.5858/134.4.625 ◽

2010 ◽

Vol 134 (4) ◽

pp. 625-629

Author(s):

Sarah L. Ondrejka ◽

Gary W. Procop ◽

Keith K. Lai ◽

Richard A. Prayson

Keyword(s):

Fatal Case ◽

Brain Biopsy ◽

Altered Mental Status ◽

Brain Parenchyma ◽

Review Of The Literature ◽

Inflammatory Infiltration ◽

Granulomatous Vasculitis ◽

Helminthic Infection ◽

Abstract Infection with the saprophagous nematode Halicephalobus species is uncommon but has been reported in horses worldwide. Only 3 human cases have been previously described, all of which have been fatal. We report a fourth fatal case, which occurred in a 39-year-old woman who presented with meningeal signs, altered mental status, and a prodromal pruritic rash. Diagnostic evaluation included an open brain biopsy, which was diagnosed as granulomatous vasculitis. The patient subsequently died after a course of steroids and cyclophosphamide. At autopsy, a robust perivascular mixed inflammatory infiltration of the brain parenchyma, meninges, and ventricular system was present with larval forms and mature nematodes morphologically consistent with Halicephalobus deletrix. Although extremely rare, this organism needs to be considered in the differential diagnosis of human helminthic infection of the central nervous system.

Immune cells and CNS physiology: Microglia and beyond

Journal of Experimental Medicine ◽

10.1084/jem.20180199 ◽

2018 ◽

Vol 216 (1) ◽

pp. 60-70 ◽

Cited By ~ 42

Author(s):

Geoffrey T. Norris ◽

Jonathan Kipnis

Keyword(s):

Central Nervous System ◽

Immune Cells ◽

Brain Function ◽

Brain Parenchyma ◽

The Body ◽

Immune Repertoire ◽

Perivascular Macrophages ◽

Cns Immunity ◽

Recent advances have directed our knowledge of the immune system from a narrative of “self” versus “nonself” to one in which immune function is critical for homeostasis of organs throughout the body. This is also the case with respect to the central nervous system (CNS). CNS immunity exists in a segregated state, with a marked partition occurring between the brain parenchyma and meningeal spaces. While the brain parenchyma is patrolled by perivascular macrophages and microglia, the meningeal spaces are supplied with a diverse immune repertoire. In this review, we posit that such partition allows for neuro–immune crosstalk to be properly tuned. Convention may imply that meningeal immunity is an ominous threat to brain function; however, recent studies have shown that its presence may instead be a steady hand directing the CNS to optimal performance.

Immune System in the Brain: A Modulatory Role on Dendritic Spine Morphophysiology?

Neural Plasticity ◽

10.1155/2012/348642 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 31

Author(s):

Oscar Kurt Bitzer-Quintero ◽

Ignacio González-Burgos

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Immune System ◽

Dendritic Spines ◽

Cell Lineage ◽

Myeloid Cell ◽

Brain Parenchyma ◽

Immune Mediators ◽

The central nervous system is closely linked to the immune system at several levels. The brain parenchyma is separated from the periphery by the blood brain barrier, which under normal conditions prevents the entry of mediators such as activated leukocytes, antibodies, complement factors, and cytokines. The myeloid cell lineage plays a crucial role in the development of immune responses at the central level, and it comprises two main subtypes: (1) resident microglia, distributed throughout the brain parenchyma; (2) perivascular macrophages located in the brain capillaries of the basal lamina and the choroid plexus. In addition, astrocytes, oligodendrocytes, endothelial cells, and, to a lesser extent, neurons are implicated in the immune response in the central nervous system. By modulating synaptogenesis, microglia are most specifically involved in restoring neuronal connectivity following injury. These cells release immune mediators, such as cytokines, that modulate synaptic transmission and that alter the morphology of dendritic spines during the inflammatory process following injury. Thus, the expression and release of immune mediators in the brain parenchyma are closely linked to plastic morphophysiological changes in neuronal dendritic spines. Based on these observations, it has been proposed that these immune mediators are also implicated in learning and memory processes.

A Rhombencephalitis Revealing HIV Virorachia

10.21203/rs.3.rs-465507/v1 ◽

2021 ◽

Author(s):

Annick Melanie MAGNEROU ◽

Martine NIDA ◽

Daniel MASSI GAMS ◽

Hugues Martial ZANGA ◽

Fidelie Scolastique NGOUNGOURE HALIMA ◽

...

Keyword(s):

Viral Suppression ◽

Treated Patient ◽

Brain Mri ◽

Undetectable Viral Load ◽

Brain Parenchyma ◽

Hiv Replication ◽

Csf Analysis ◽

Persistent Inflammation ◽

Abstract One of the possible causes of persistent inflammation of the brain parenchyma in the age of antiretrovirals is residual HIV replication, despite effective viral suppression in the bloodstream with Antiretroviral treatment (ART). The central nervous system (CNS) is infected early during primary HIV infection and is one of the reservoirs of this virus during chronic infection. Inadequate penetration of certain ART into the CNS could promote some degree of intrathecal HIV replication.We describe the case of an HIV-infected patient compliant to ART with an undetectable viral load in the blood but present in the cerebrospinal fluid (CSF). The patient presented with subacute rhombencephalitis due to HIV which was fatal to him.An HIV-infected and treated patient, well controlled on ART, with new neurological disorders, should be promptly investigated by brain MRI and CSF analysis for exhaustive detection of viruses including that of HIV itself.

Unexpected intracranial location of a Cephenemyia stimulator larva in a roe deer, Capreolus capreolus, revealed by computed tomography

Galemys Spanish Journal of Mammalogy ◽

10.7325/galemys.2021.a2 ◽

2021 ◽

Vol 33 ◽

pp. 1-7

Author(s):

Luis E. Fidalgo ◽

Ana M. López-Beceiro ◽

Carlos Martínez-Carrasco ◽

Noelia Caparrós-Fontarosa ◽

Antonio Sánchez ◽

...

Keyword(s):

Computed Tomography ◽

Central Nervous System ◽

Roe Deer ◽

Capreolus Capreolus ◽

Brain Parenchyma ◽

Anatomical Location ◽

Migration Route ◽

Hemorrhagic Lesion ◽

In this study we describe the finding of a Cephenemyia stimulator larva in the brain of a roe deer (Capreolus capreolus) after performing a computed tomography (CT) scan of its head. Despite this anatomical location of oestrid larvae could be relatively frequent in other genera, such as Oestrus, to our knowledge, this is the first reported case involving the genus Cephenemyia. Concretely, a second-instar C. stimulator larvae was found in the basis of the cranium. The location of a macroscopic hemorrhagic lesion involving the brain parenchyma peripheral to the location of the larva suggests that tissue colonization occurred before the animal was hunted. Since no detectable alterations or damage to the cranial bones were observed, we suggest a possible larval migration route drilling the skull bones. Finally, we propose the use of the term “neuromyiasis” to be referred to the invasion of the central nervous system by dipteran larvae, particularly oestrids.

Immovable Object Meets Unstoppable Force? Dialogue Between Resident and Peripheral Myeloid Cells in the Inflamed Brain

Frontiers in Immunology ◽

10.3389/fimmu.2020.600822 ◽

2020 ◽

Vol 11 ◽

Author(s):

Alanna G. Spiteri ◽

Claire L. Wishart ◽

Nicholas J. C. King

Keyword(s):

Myeloid Cells ◽

Cell Types ◽

Brain Parenchyma ◽

Specific Cell ◽

Novel Treatments ◽

Experimental Systems ◽

Immune Mediated ◽

Recent Developments ◽

Inflammation of the brain parenchyma is characteristic of neurodegenerative, autoimmune, and neuroinflammatory diseases. During this process, microglia, which populate the embryonic brain and become a permanent sentinel myeloid population, are inexorably joined by peripherally derived monocytes, recruited by the central nervous system. These cells can quickly adopt a morphology and immunophenotype similar to microglia. Both microglia and monocytes have been implicated in inducing, enhancing, and/or maintaining immune-mediated pathology and thus disease progression in a number of neuropathologies. For many years, experimental and analytical systems have failed to differentiate resident microglia from peripherally derived myeloid cells accurately. This has impeded our understanding of their precise functions in, and contributions to, these diseases, and hampered the development of novel treatments that could target specific cell subsets. Over the past decade, microglia have been investigated more intensively in the context of neuroimmunological research, fostering the development of more precise experimental systems. In light of our rapidly growing understanding of these cells, we discuss the differential origins of microglia and peripherally derived myeloid cells in the inflamed brain, with an analysis of the problems resolving these cell types phenotypically and morphologically, and highlight recent developments enabling more precise identification.

Herpetic Meningoencephalitis by Vertical Transmission: A Case Report and Systematic Review

10.34256/mdnt2117 ◽

2021 ◽

Vol 2 (1) ◽

pp. 35-41

Author(s):

Julia Teles Triglia Pinto ◽

◽

Ana Carolina Tomasella Auad ◽

Gabrielle Menegucci ◽

Marília Gabriela Palácio Galbiatti ◽

...

Keyword(s):

Specific Treatment ◽

Brain Parenchyma ◽

High Rate ◽

Neurological Damage ◽

Neurological Sequelae ◽

Spontaneous Vaginal Delivery ◽

Herpetic Encephalitis ◽

Simplex Virus ◽

Objective: To report a case of vertical herpetic meningoencephalitis. Results: The involvement of the central nervous system (CNS) in infection by HSV (herpes simplex virus), HSV-1 or HSV-2, causes an acute inflammatory process in the brain parenchyma, leading to herpetic encephalitis. It is a feared form of the disease due to its severity and its high rate of morbidity and mortality. Its rapid fatal progression can be prevented from early suspicion and treatment, which is essential when taking into account their neurological sequelae since survivors have motor sequelae, behavioral disorders, or epilepsy. The present work reports the case of a newborn male with spontaneous vaginal delivery who, at 19 days of age, started to experience fever, irritability, difficulty in eating, spasms, tremors of the upper limbs, deviation of the eyes, and seizures of difficult to control, together with CFE and serological changes, in addition to imaging tests compatible with herpetic meningoencephalitis, progressing with a very serious evolution despite the institution of specific treatment for CNS herpetic infection, evolving with important neurological sequelae. Conclusion: The sequels resulting from herpetic encephalitis not properly diagnosed, or even late, leads from severe neurological damage to death. Therefore, it is extremely important to start empirical treatment with antiviral drugs to reduce the sequelae mentioned above.