scholarly journals Microglia Fighting for Neurological and Mental Health: On the Central Nervous System Frontline of COVID-19 Pandemic

2021 ◽  
Vol 15 ◽  
Author(s):  
Elisa Gonçalves de Andrade ◽  
Eva Šimončičová ◽  
Micaël Carrier ◽  
Haley A. Vecchiarelli ◽  
Marie-Ève Robert ◽  
...  
Keyword(s):  
Mental Health ◽  
Central Nervous System ◽  
Nervous System ◽  
Inflammatory Responses ◽  
Psychiatric Symptoms ◽  
Brain Parenchyma ◽  
Molecular Signature ◽  
The Central Nervous System ◽  
Psychiatric Manifestations ◽  
The Brain

Coronavirus disease 2019 (COVID-19) is marked by cardio-respiratory alterations, with increasing reports also indicating neurological and psychiatric symptoms in infected individuals. During COVID-19 pathology, the central nervous system (CNS) is possibly affected by direct severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) invasion, exaggerated systemic inflammatory responses, or hypoxia. Psychosocial stress imposed by the pandemic further affects the CNS of COVID-19 patients, but also the non-infected population, potentially contributing to the emergence or exacerbation of various neurological or mental health disorders. Microglia are central players of the CNS homeostasis maintenance and inflammatory response that exert their crucial functions in coordination with other CNS cells. During homeostatic challenges to the brain parenchyma, microglia modify their density, morphology, and molecular signature, resulting in the adjustment of their functions. In this review, we discuss how microglia may be involved in the neuroprotective and neurotoxic responses against CNS insults deriving from COVID-19. We examine how these responses may explain, at least partially, the neurological and psychiatric manifestations reported in COVID-19 patients and the general population. Furthermore, we consider how microglia might contribute to increased CNS vulnerability in certain groups, such as aged individuals and people with pre-existing conditions.

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

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
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 ◽  
The Brain

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.

scholarly journals Modern aspects of neuropathogenesis and neurological manifestations of COVID-19

2021 ◽  
Vol 17 (2) ◽  
pp. 6-15
Author(s):  
L.A. Dziak ◽  
O.S. Tsurkalenko ◽  
K.V. Chekha ◽  
V.M. Suk
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Psychiatric Symptoms ◽  
Clinical Manifestations ◽  
The Body ◽  
Altered Level ◽  
Wide Range ◽  
The Central Nervous System ◽  
The Brain

Coronavirus infection is a systemic pathology resulting in impairment of the nervous system. The involvement of the central nervous system in COVID-19 is diverse by clinical manifestations and main mechanisms. The mechanisms of interrelations between SARS-CoV-2 and the nervous system include a direct virus-induced lesion of the central nervous system, inflammatory-mediated impairment, thrombus burden, and impairment caused by hypoxia and homeostasis. Due to the multi-factor mechanisms (viral, immune, hypoxic, hypercoagulation), the SARS-CoV-2 infection can cause a wide range of neurological disorders involving both the central and peripheral nervous system and end organs. Dizziness, headache, altered level of consciousness, acute cerebrovascular diseases, hypogeusia, hyposmia, peripheral neuropathies, sleep disorders, delirium, neuralgia, myalgia are the most common signs. The structural and functional changes in various organs and systems and many neurological symptoms are determined to persist after COVID-19. Regardless of the numerous clinical reports about the neurological and psychiatric symptoms of COVID-19 as before it is difficult to determine if they are associated with the direct or indirect impact of viral infection or they are secondary to hypoxia, sepsis, cytokine reaction, and multiple organ failure. Penetrated the brain, COVID-19 can impact the other organs and systems and the body in general. Given the mechanisms of impairment, the survivors after COVID-19 with the infection penetrated the brain are more susceptible to more serious diseases such as Parkinson’s disease, cognitive decline, multiple sclerosis, and other autoimmune diseases. Given the multi-factor pathogenesis of COVID-19 resulting in long-term persistence of the clinical symptoms due to impaired neuroplasticity and neurogenesis followed by cholinergic deficiency, the usage of Neuroxon® 1000 mg a day with twice-day dosing for 30 days. Also, a long-term follow-up and control over the COVID-19 patients are recommended for the prophylaxis, timely determination, and correction of long-term complications.

Arachidonic Acid Derivatives and Neuroinflammation

2021 ◽  
Vol 20 ◽  
Author(s):  
Era Gorica ◽  
Vincenzo Calderone
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Arachidonic Acid ◽  
Prostaglandin E2 ◽  
Phospholipase A2 ◽  
Inflammatory Responses ◽  
The Central Nervous System ◽  
The Brain ◽  
Arachidonic Acid Derivatives

: Neuroinflammation is characterized by dysregulated inflammatory responses localized within the brain and spinal cord. Neuroinflammation plays a pivotal role in the onset of several neurodegenerative disorders and is considered a typical feature of these disorders. Microglia perform primary immune surveillance and macrophage-like activities within the central nervous system. Activated microglia are predominant players in the central nervous system response to damage related to stroke, trauma, and infection. Moreover, microglial activation per se leads to a proinflammatory response and oxidative stress. During the release of cytokines and chemokines, cyclooxygenases and phospholipase A2 are stimulated. Elevated levels of these compounds play a significant role in immune cell recruitment into the brain. Cyclic phospholipase A2 plays a fundamental role in the production of prostaglandins by releasing arachidonic acid. In turn, arachidonic acid is biotransformed through different routes into several mediators that are endowed with pivotal roles in the regulation of inflammatory processes. Some experimental models of neuroinflammation exhibit an increase in cyclic phospholipase A2, leukotrienes, and prostaglandins such as prostaglandin E2, prostaglandin D2, or prostacyclin. However, findings on the role of the prostacyclin receptors have revealed that their signalling suppresses Th2-mediated inflammatory responses. In addition, other in vitro evidence suggests that prostaglandin E2 may inhibit the production of some inflammatory cytokines, attenuating inflammatory events such as mast cell degranulation or inflammatory leukotriene production. Based on these conflicting experimental data, the role of arachidonic acid derivatives in neuroinflammation remains a challenging issue.

scholarly journals Physiology of Microglia

2011 ◽  
Vol 91 (2) ◽  
pp. 461-553 ◽  
Author(s):  
Helmut Kettenmann ◽  
Uwe-Karsten Hanisch ◽  
Mami Noda ◽  
Alexei Verkhratsky
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Immune Cell ◽  
Brain Parenchyma ◽  
Microglial Cells ◽  
Activation Process ◽  
Normal Brain ◽  
The Central Nervous System ◽  
Cellular Compartments ◽  
The Brain

Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed “resting microglia.” Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the “activated microglial cell.” This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.

scholarly journals Spinal Neurocysticercosis: A Rare Variant of a Common Parasitic Infection

2016 ◽  
Vol 36 (01) ◽  
pp. 66-70
Author(s):  
Paulo Mesquita Filho ◽  
Nério Azambuja Junior ◽  
José Vanzin ◽  
Rafael Annes ◽  
Daniel Varela ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Parasitic Infection ◽  
Brain Parenchyma ◽  
Clinical Scenario ◽  
Nerve Roots ◽  
Csf Analysis ◽  
The Central Nervous System ◽  
The Brain

Neurocysticercosis is the most common parasitic infection affecting the central nervous system, usually involving the brain parenchyma, intracranial subarachnoid space, or ventricular system. In rare cases, there is involvement of the spine (vertebral, epidural, subdural, arachnoid, or intramedullary). Even in endemic regions, this variant is rare, with an incidence below 5% of all patients. The diagnosis is made based on the symptoms, which can be very unspecific, imaging and CSF analysis, with biopsy as a possibility. Treatment is usually curative, but important deficits can develop, due to compression of the spinal cord or nerve roots, arachnoiditis, or meningitis. We present the case of a patient who developed this entity, with poor clinical scenario, and review the literature on the topic.

scholarly journals Blood-brain barrier-restricted translocation of Toxoplasma gondii from cortical capillaries

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Gabriela C Olivera ◽  
Emily C Ross ◽  
Christiane Peuckert ◽  
Antonio Barragan
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Toxoplasma Gondii ◽  
Blood Brain Barrier ◽  
Brain Parenchyma ◽  
Brain Barrier ◽  
Blood Brain ◽  
The Central Nervous System ◽  
Cortical Capillaries ◽  
The Brain

The cellular barriers of the central nervous system proficiently protect the brain parenchyma from infectious insults. Yet, the single-celled parasite Toxoplasma gondii commonly causes latent cerebral infection in humans and other vertebrates. Here, we addressed the role of the cerebral vasculature in the passage of T. gondii to the brain parenchyma. Shortly after inoculation in mice, parasites mainly localized to cortical capillaries, in preference over post-capillary venules, cortical arterioles or meningeal and choroidal vessels. Early invasion to the parenchyma (days 1-5) occurred in absence of a measurable increase in blood-brain barrier (BBB) permeability, perivascular leukocyte cuffs or hemorrhage. However, sparse focalized permeability elevations were detected adjacently to replicative parasite foci. Further, T. gondii triggered inflammatory responses in cortical microvessels and endothelium. Pro- and anti-inflammatory treatments of mice with LPS and hydrocortisone, respectively, impacted BBB permeability and parasite loads in the brain parenchyma. Finally, pharmacological inhibition or Cre/loxP conditional knockout of endothelial focal adhesion kinase (FAK), a BBB intercellular junction regulator, facilitated parasite translocation to the brain parenchyma. The data reveal that the initial passage of T. gondii to the central nervous system occurs principally across cortical capillaries. The integrity of the microvascular BBB restricts parasite transit, which conversely is exacerbated by the inflammatory response.

scholarly journals Th17 lymphocytes traffic to the central nervous system independently of α4 integrin expression during EAE

2011 ◽  
Vol 208 (12) ◽  
pp. 2465-2476 ◽  
Author(s):  
Veit Rothhammer ◽  
Sylvia Heink ◽  
Franziska Petermann ◽  
Rajneesh Srivastava ◽  
Malte C. Claussen ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
T Cells ◽  
Nervous System ◽  
Th17 Cells ◽  
Brain Parenchyma ◽  
Th1 Cells ◽  
Th17 Lymphocytes ◽  
The Central Nervous System ◽  
The Brain

The integrin α4β1 (VLA-4) is used by encephalitogenic T cells to enter the central nervous system (CNS). However, both Th1 and Th17 cells are capable of inducing experimental autoimmune encephalomyelitis (EAE), and the molecular cues mediating the infiltration of Th1 versus Th17 cells into the CNS have not yet been defined. We investigated how blocking of α4 integrins affected trafficking of Th1 and Th17 cells into the CNS during EAE. Although antibody-mediated inhibition of α4 integrins prevented EAE when MOG35-55-specific Th1 cells were adoptively transferred, Th17 cells entered the brain, but not the spinal cord parenchyma, irrespective of α4 blockade. Accordingly, T cell–conditional α4-deficient mice were not resistant to actively induced EAE but showed an ataxic syndrome with predominantly supraspinal infiltrates of IL-23R+CCR6+CD4+ T cells. The entry of α4-deficient Th17 cells into the CNS was abolished by blockade of LFA-1 (αLβ2 integrin). Thus, Th1 cells preferentially infiltrate the spinal cord via an α4 integrin–mediated mechanism, whereas the entry of Th17 cells into the brain parenchyma occurs in the absence of α4 integrins but is dependent on the expression of αLβ2. These observations have implications for the understanding of lesion localization, immunosurveillance, and drug design in multiple sclerosis.

scholarly journals The Brain Entangled: The Contribution of Neutrophil Extracellular Traps to the Diseases of the Central Nervous System

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1477 ◽  
Author(s):  
Aneta Manda-Handzlik ◽  
Urszula Demkow
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Proteolytic Enzymes ◽  
Neutrophil Extracellular Traps ◽  
Brain Parenchyma ◽  
Free Oxygen Radicals ◽  
Extracellular Traps ◽  
Pathological Conditions ◽  
The Central Nervous System ◽  
The Brain

Under normal conditions, neutrophils are restricted from trafficking into the brain parenchyma and cerebrospinal fluid by the presence of the brain–blood barrier (BBB). Yet, infiltration of the central nervous system (CNS) by neutrophils is a well-known phenomenon in the course of different pathological conditions, e.g., infection, trauma or neurodegeneration. Different studies have shown that neutrophil products, i.e., free oxygen radicals and proteolytic enzymes, play an important role in the pathogenesis of BBB damage. It was recently observed that accumulating granulocytes may release neutrophil extracellular traps (NETs), which damage the BBB and directly injure surrounding neurons. In this review, we discuss the emerging role of NETs in various pathological conditions affecting the CNS.

scholarly journals Cytokines, neurophysiology, neuropsychology, and psychiatric symptoms

2003 ◽  
Vol 5 (2) ◽  
pp. 139-153
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Immune System ◽  
Major Depression ◽  
Psychiatric Symptoms ◽  
Sickness Behavior ◽  
Signal Transducers ◽  
The Central Nervous System ◽  
The Brain

Recent research has overcome the old paradigms of the brain as an immunologically privileged organ, and of the exclusive role of neurotransmitters and neuropeptides as signal transducers in the central nervous system. Growing evidence suggests that the signal proteins of the immune system - the cytokines - are also involved in modulation of behavior and induction of psychiatric symptoms. This article gives an overview on the nature of cytokines and the proposed mechanisms of immune-to-brain interaction. The role of cytokines in psychiatric symptoms, syndromes, and disorders like sickness behavior, major depression, and schizophrenia are discussed together with recent immunogenetic findings.

Infections of the central nervous system

2020 ◽  
pp. 217-228
Author(s):  
Guleed Adan ◽  
Sam Nightingale ◽  
Christine Burness ◽  
Tom Solomon
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Psychiatric Symptoms ◽  
Early Recognition ◽  
Psychiatric Patients ◽  
Cns Infection ◽  
Cns Infections ◽  
System P ◽  
The Central Nervous System ◽  
Psychiatric Manifestations

Central nervous system (CNS) infections, caused by various pathogens, can lead to a wide range of neuropsychiatric sequelae, including acute psychosis, mood disorders, and chronic dementias. Early recognition is critical as brain infections are often treatable and possible neuropsychiatric illness can be reversed if the diagnosis is timely. In addition to psychiatric symptoms, CNS infections may also present with other signs such as fever, meningism, cranial nerve deficit, and seizures. Although the presence of these additional features can often provide a clue to an underlying CNS infection, they are not always present; hence CNS infections should be considered in the differential diagnosis of psychiatric patients in certain situations. In this chapter, CNS infections that have psychiatric manifestations or have psychiatric sequelae are discussed, in particular HIV, neurosyphilis, meningitis, and encephalitis.

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