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1.
Pharmacol Res Perspect ; 10(2): e00926, 2022 04.
Article in English | MEDLINE | ID: covidwho-1694654

ABSTRACT

The chronic neurological aspects of traumatic brain injury, post-stroke syndromes, long COVID-19, persistent Lyme disease, and influenza encephalopathy having close pathophysiological parallels that warrant being investigated in an integrated manner. A mechanism, common to all, for this persistence of the range of symptoms common to these conditions is described. While TNF maintains cerebral homeostasis, its excessive production through either pathogen-associated molecular patterns or damage-associated molecular patterns activity associates with the persistence of the symptoms common across both infectious and non-infectious conditions. The case is made that this shared chronicity arises from a positive feedback loop causing the persistence of the activation of microglia by the TNF that these cells generate. Lowering this excess TNF is the logical way to reducing this persistent, TNF-maintained, microglial activation. While too large to negotiate the blood-brain barrier effectively, the specific anti-TNF biological, etanercept, shows promise when administered by the perispinal route, which allows it to bypass this obstruction.


Subject(s)
COVID-19/complications , Etanercept/therapeutic use , Stroke/complications , COVID-19/metabolism , COVID-19/pathology , Etanercept/administration & dosage , Humans , Injections, Spinal , Microglia/metabolism , Microglia/pathology , Stroke/metabolism , Syndrome , Tumor Necrosis Factor-alpha/metabolism
2.
Genome Biol ; 23(1): 33, 2022 01 24.
Article in English | MEDLINE | ID: covidwho-1649470

ABSTRACT

We consider an increasingly popular study design where single-cell RNA-seq data are collected from multiple individuals and the question of interest is to find genes that are differentially expressed between two groups of individuals. Towards this end, we propose a statistical method named IDEAS (individual level differential expression analysis for scRNA-seq). For each gene, IDEAS summarizes its expression in each individual by a distribution and then assesses whether these individual-specific distributions are different between two groups of individuals. We apply IDEAS to assess gene expression differences of autism patients versus controls and COVID-19 patients with mild versus severe symptoms.


Subject(s)
Autistic Disorder/genetics , COVID-19/genetics , Sequence Analysis, RNA/methods , Single-Cell Analysis/methods , Software , Autistic Disorder/metabolism , Autistic Disorder/pathology , COVID-19/metabolism , COVID-19/pathology , COVID-19/virology , Case-Control Studies , Gene Expression Profiling , Gene Expression Regulation , Humans , Microglia/metabolism , Microglia/pathology , Nerve Tissue Proteins/classification , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , SARS-CoV-2/pathogenicity , Severity of Illness Index , Whole Exome Sequencing
3.
Metab Brain Dis ; 37(3): 711-728, 2022 03.
Article in English | MEDLINE | ID: covidwho-1606836

ABSTRACT

The overload cytosolic free Ca2+ (cCa2+) influx-mediated excessive generation of oxidative stress in the pathophysiological conditions induces neuronal and cellular injury via the activation of cation channels. TRPM2 and TRPV4 channels are activated by oxidative stress, and their specific antagonists have not been discovered yet. The antioxidant and anti-Covid-19 properties of carvacrol (CARV) were recently reported. Hence, I suspected possible antagonist properties of CARV against oxidative stress (OS)/ADP-ribose (ADPR)-induced TRPM2 and GSK1016790A (GSK)-mediated TRPV4 activations in neuronal and kidney cells. I investigated the antagonist role of CARV on the activations of TRPM2 and TRPV4 in SH-SY5Y neuronal, BV-2 microglial, and HEK293 cells. The OS/ADPR and GSK in the cells caused to increase of TRPM2/TRPV4 current densities and overload cytosolic free Ca2+ (cCa2+) influx with an increase of mitochondrial membrane potential, cytosolic (cROS), and mitochondrial (mROS) ROS. The changes were not observed in the absence of TRPM2 and TRPV4 or the presence of Ca2+ free extracellular buffer and PARP-1 inhibitors (PJ34 and DPQ). When OS-induced TRPM2 and GSK-induced TRPV4 activations were inhibited by the treatment of CARV, the increase of cROS, mROS, lipid peroxidation, apoptosis, cell death, cCa2+ concentration, caspase -3, and caspase -9 levels were restored via upregulation of glutathione and glutathione peroxidase. In conclusion, the treatment of CARV modulated the TRPM2 and TRPV4-mediated overload Ca2+ influx and may provide an avenue for protecting TRPM2 and TRPV4-mediated neurodegenerative diseases associated with the increase of mROS and cCa2+. The possible TRPM2 and TRPV4 blocker action of carvacrol (CARV) via the modulation oxidative stress and apoptosis in the SH-SY5Y neuronal cells. TRPM2 is activated by DNA damage-induced (via PARP-1 activation) ADP-ribose (ADPR) and reactive oxygen species (ROS) (H2O2), although it is inhibited by nonspecific inhibitors (ACA and 2-APB). TRPV4 is activated by the treatments of GSK1016790A (GSK), although it is inhibited by a nonspecific inhibitor (ruthenium red, RuRe). The treatment of GSK induces excessive generation of ROS. The accumulation of free cytosolic Ca2+ (cCa2+) via the activations of TRPM2 and TRPV4 in the mitochondria causes the increase of mitochondrial membrane depolarization (ΔΨm). In turn, the increase of ΔΨm causes the excessive generation of ROS. The TRPM2 and TRPV4-induced the excessive generations of ROS result in the increase of apoptosis and cell death via the activations of caspase -3 (Casp-3) and caspase -9 (Casp-9) in the neuronal cells, although their oxidant actions decrease the glutathione (GSH) and glutathione peroxidase (GSHPx) levels. The oxidant and apoptotic adverse actions of TRPM2 and TRPV4 are modulated by the treatment of CARV.


Subject(s)
Antioxidants/pharmacology , Cymenes/pharmacology , TRPM Cation Channels/antagonists & inhibitors , TRPV Cation Channels/antagonists & inhibitors , Apoptosis/drug effects , Calcium/metabolism , Caspase 3/metabolism , Caspase 9/metabolism , HEK293 Cells , Humans , Kidney/drug effects , Kidney/metabolism , Membrane Potential, Mitochondrial/drug effects , Microglia/drug effects , Microglia/metabolism , Neurons/drug effects , Neurons/metabolism , Oxidative Stress/drug effects , Reactive Oxygen Species
4.
J Neuroinflammation ; 19(1): 2, 2022 Jan 04.
Article in English | MEDLINE | ID: covidwho-1603365

ABSTRACT

BACKGROUND: Anxiety disorders are the most prevalent mental illnesses in the U.S. and are estimated to consume one-third of the country's mental health treatment cost. Although anxiolytic therapies are available, many patients still exhibit treatment resistance, relapse, or substantial side effects. Further, due to the COVID-19 pandemic and stay-at-home order, social isolation, fear of the pandemic, and unprecedented times, the incidence of anxiety has dramatically increased. Previously, we have demonstrated dihydromyricetin (DHM), the major bioactive flavonoid extracted from Ampelopsis grossedentata, exhibits anxiolytic properties in a mouse model of social isolation-induced anxiety. Because GABAergic transmission modulates the immune system in addition to the inhibitory signal transmission, we investigated the effects of short-term social isolation on the neuroimmune system. METHODS: Eight-week-old male C57BL/6 mice were housed under absolute social isolation for 4 weeks. The anxiety-like behaviors after DHM treatment were examined using elevated plus-maze and open field behavioral tests. Gephyrin protein expression, microglial profile changes, NF-κB pathway activation, cytokine level, and serum corticosterone were measured. RESULTS: Socially isolated mice showed increased anxiety levels, reduced exploratory behaviors, and reduced gephyrin levels. Also, a dynamic alteration in hippocampal microglia were detected illustrated as a decline in microglia number and overactivation as determined by significant morphological changes including decreases in lacunarity, perimeter, and cell size and increase in cell density. Moreover, social isolation induced an increase in serum corticosterone level and activation in NF-κB pathway. Notably, DHM treatment counteracted these changes. CONCLUSION: The results suggest that social isolation contributes to neuroinflammation, while DHM has the ability to improve neuroinflammation induced by anxiety.


Subject(s)
Flavonols/pharmacology , Inflammation Mediators/antagonists & inhibitors , Inflammation Mediators/metabolism , Microglia/drug effects , Microglia/metabolism , Social Isolation/psychology , Animals , Anxiety/metabolism , Anxiety/prevention & control , Anxiety/psychology , Flavonols/therapeutic use , Male , Maze Learning/drug effects , Maze Learning/physiology , Mice , Mice, Inbred C57BL
5.
Mol Neurobiol ; 59(1): 445-458, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1491383

ABSTRACT

In addition to respiratory complications produced by SARS-CoV-2, accumulating evidence suggests that some neurological symptoms are associated with the disease caused by this coronavirus. In this study, we investigated the effects of the SARS-CoV-2 spike protein S1 stimulation on neuroinflammation in BV-2 microglia. Analyses of culture supernatants revealed an increase in the production of TNF-α, IL-6, IL-1ß and iNOS/NO. S1 also increased protein levels of phospho-p65 and phospho-IκBα, as well as enhanced DNA binding and transcriptional activity of NF-κB. These effects of the protein were blocked in the presence of BAY11-7082 (1 µM). Exposure of S1 to BV-2 microglia also increased the protein levels of NLRP3 inflammasome and enhanced caspase-1 activity. Increased protein levels of p38 MAPK was observed in BV-2 microglia stimulated with the spike protein S1 (100 ng/ml), an action that was reduced in the presence of SKF 86,002 (1 µM). Results of immunofluorescence microscopy showed an increase in TLR4 protein expression in S1-stimulated BV-2 microglia. Furthermore, pharmacological inhibition with TAK 242 (1 µM) and transfection with TLR4 small interfering RNA resulted in significant reduction in TNF-α and IL-6 production in S1-stimulated BV-2 microglia. These results have provided the first evidence demonstrating S1-induced neuroinflammation in BV-2 microglia. We propose that induction of neuroinflammation by this protein in the microglia is mediated through activation of NF-κB and p38 MAPK, possibly as a result of TLR4 activation. These results contribute to our understanding of some of the mechanisms involved in CNS pathologies of SARS-CoV-2.


Subject(s)
Microglia/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Animals , Caspase 1/metabolism , Cell Line , Furans/pharmacology , Indenes/pharmacology , Inflammasomes/metabolism , Interleukin-1beta/genetics , Interleukin-6/metabolism , Mice , Microglia/pathology , NF-kappa B/metabolism , Nitric Oxide/metabolism , Nitric Oxide Synthase Type II/metabolism , Nitriles/pharmacology , RNA, Small Interfering , Recombinant Proteins/metabolism , Sulfonamides/pharmacology , Sulfones/pharmacology , Toll-Like Receptor 4/metabolism , Tumor Necrosis Factor-alpha/metabolism , p38 Mitogen-Activated Protein Kinases/metabolism
6.
J Neuroinflammation ; 18(1): 167, 2021 Jul 29.
Article in English | MEDLINE | ID: covidwho-1331945

ABSTRACT

BACKGROUND: Neurological complications are common in patients affected by COVID-19 due to the ability of SARS-CoV-2 to infect brains. While the mechanisms of this process are not fully understood, it has been proposed that SARS-CoV-2 can infect the cells of the neurovascular unit (NVU), which form the blood-brain barrier (BBB). The aim of the current study was to analyze the expression pattern of the main SARS-CoV-2 receptors in naïve and HIV-1-infected cells of the NVU in order to elucidate a possible pathway of the virus entry into the brain and a potential modulatory impact of HIV-1 in this process. METHODS: The gene and protein expression profile of ACE2, TMPRSS2, ADAM17, BSG, DPP4, AGTR2, ANPEP, cathepsin B, and cathepsin L was assessed by qPCR, immunoblotting, and immunostaining, respectively. In addition, we investigated if brain endothelial cells can be affected by the exposure to the S1 subunit of the S protein, the domain responsible for the direct binding of SARS-CoV-2 to the ACE2 receptors. RESULTS: The receptors involved in SARS-CoV-2 infection are co-expressed in the cells of the NVU, especially in astrocytes and microglial cells. These receptors are functionally active as exposure of endothelial cells to the SARS CoV-2 S1 protein subunit altered the expression pattern of tight junction proteins, such as claudin-5 and ZO-1. Additionally, HIV-1 infection upregulated ACE2 and TMPRSS2 expression in brain astrocytes and microglia cells. CONCLUSIONS: These findings provide key insight into SARS-CoV-2 recognition by cells of the NVU and may help to develop possible treatment of CNS complications of COVID-19.


Subject(s)
Blood Vessels/metabolism , COVID-19/complications , HIV Infections/metabolism , HIV-1 , Neurons/metabolism , Receptors, Virus/genetics , Receptors, Virus/metabolism , SARS-CoV-2 , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Astrocytes/metabolism , Brain Diseases/etiology , Cells, Cultured , Endothelium, Vascular/metabolism , Humans , Microglia/metabolism , Nervous System Diseases/etiology , Primary Cell Culture , Receptor, Angiotensin, Type 2 , Virus Replication
7.
Mol Neurobiol ; 58(10): 5090-5111, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1303372

ABSTRACT

The virus "acute respiratory syndrome coronavirus 2" (SARS-CoV-2) is the etiologic agent of coronavirus disease 2019 (COVID-19), initially responsible for an outbreak of pneumonia in Wuhan, China, which, due to the high level of contagion and dissemination, has become a pandemic. The clinical picture varies from mild to critical cases; however, all of these signs already show neurological problems, from sensory loss to neurological diseases. Thus, patients with multiple sclerosis (MS) infected with the new coronavirus are more likely to develop severe conditions; in addition to worsening the disease, this is due to the high level of pro-inflammatory cytokines, which is closely associated with increased mortality both in COVID-19 and MS. This increase is uncontrolled and exaggerated, characterizing the cytokine storm, so a possible therapy for this neuronal inflammation is the modulation of the cholinergic anti-inflammatory pathway, since acetylcholine (ACh) acts to reduce pro-inflammatory cytokines and acts directly on the brain for being released by cholinergic neurons, as well as acting on other cells such as immune and blood cells. In addition, due to tissue damage, there is an exacerbated release of adenosine triphosphate (ATP), potentiating the inflammatory process and activating purinergic receptors which act directly on neuroinflammation and positively modulate the inflammatory cycle. Associated with this, in neurological pathologies, there is greater expression of P2X7 in the cells of the microglia, which positively activates the immune inflammatory response. Thus, the administration of blockers of this receptor can act in conjunction with the action of ACh in the anticholinergic inflammatory pathway. Finally, there will be a reduction in the cytokine storm and triggered hyperinflammation, as well as the level of mortality in patients with multiple sclerosis infected with SARS-CoV-2 and the development of possible neurological damage.


Subject(s)
COVID-19/metabolism , Cytokine Release Syndrome/metabolism , Immunologic Factors/therapeutic use , Multiple Sclerosis/metabolism , Cytokine Release Syndrome/etiology , Cytokines/metabolism , Humans , Immunologic Factors/adverse effects , Microglia/metabolism , Multiple Sclerosis/drug therapy
8.
Int J Mol Sci ; 22(13)2021 Jun 29.
Article in English | MEDLINE | ID: covidwho-1304667

ABSTRACT

Amyloid beta (Aß)-induced abnormal neuroinflammation is recognized as a major pathological feature of Alzheimer's disease (AD), which results in memory impairment. Research exploring low-grade systemic inflammation and its impact on the development and progression of neurodegenerative disease has increased. A particular research focus has been whether systemic inflammation arises only as a secondary effect of disease, or it is also a cause of pathology. The inflammasomes, and more specifically the NLRP3 inflammasome, are crucial components of the innate immune system and are usually activated in response to infection or tissue damage. Although inflammasome activation plays critical roles against various pathogens in host defense, overactivation of inflammasome contributes to the pathogenesis of inflammatory diseases, including acute central nervous system (CNS) injuries and chronic neurodegenerative diseases, such as AD. This review summarizes the current literature on the role of the NLRP3 inflammasome in the pathogenesis of AD, and its involvement in infections, particularly SARS-CoV-2. NLRP3 might represent the crossroad between the hypothesized neurodegeneration and the primary COVID-19 infection.


Subject(s)
Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Inflammasomes/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Alzheimer Disease/metabolism , Animals , Coronavirus/pathogenicity , Humans , Immunity, Innate , Microglia/metabolism , Virus Diseases/immunology , Virus Diseases/pathology
9.
Int J Mol Sci ; 22(13)2021 Jun 29.
Article in English | MEDLINE | ID: covidwho-1295856

ABSTRACT

Amyloid beta (Aß)-induced abnormal neuroinflammation is recognized as a major pathological feature of Alzheimer's disease (AD), which results in memory impairment. Research exploring low-grade systemic inflammation and its impact on the development and progression of neurodegenerative disease has increased. A particular research focus has been whether systemic inflammation arises only as a secondary effect of disease, or it is also a cause of pathology. The inflammasomes, and more specifically the NLRP3 inflammasome, are crucial components of the innate immune system and are usually activated in response to infection or tissue damage. Although inflammasome activation plays critical roles against various pathogens in host defense, overactivation of inflammasome contributes to the pathogenesis of inflammatory diseases, including acute central nervous system (CNS) injuries and chronic neurodegenerative diseases, such as AD. This review summarizes the current literature on the role of the NLRP3 inflammasome in the pathogenesis of AD, and its involvement in infections, particularly SARS-CoV-2. NLRP3 might represent the crossroad between the hypothesized neurodegeneration and the primary COVID-19 infection.


Subject(s)
Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Inflammasomes/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Alzheimer Disease/metabolism , Animals , Coronavirus/pathogenicity , Humans , Immunity, Innate , Microglia/metabolism , Virus Diseases/immunology , Virus Diseases/pathology
10.
Front Immunol ; 12: 656700, 2021.
Article in English | MEDLINE | ID: covidwho-1211815

ABSTRACT

SARS-CoV-2, the novel coronavirus infection has consistently shown an association with neurological anomalies in patients, in addition to its usual respiratory distress syndrome. Multi-organ dysfunctions including neurological sequelae during COVID-19 persist even after declining viral load. We propose that SARS-CoV-2 gene product, Spike, is able to modify the host exosomal cargo, which gets transported to distant uninfected tissues and organs and can initiate a catastrophic immune cascade within Central Nervous System (CNS). SARS-CoV-2 Spike transfected cells release a significant amount of exosomes loaded with microRNAs such as miR-148a and miR-590. microRNAs gets internalized by human microglia and suppress target gene expression of USP33 (Ubiquitin Specific peptidase 33) and downstream IRF9 levels. Cellular levels of USP33 regulate the turnover time of IRF9 via deubiquitylation. Our results also demonstrate that absorption of modified exosomes effectively regulate the major pro-inflammatory gene expression profile of TNFα, NF-κB and IFN-ß. These results uncover a bystander pathway of SARS-CoV-2 mediated CNS damage through hyperactivation of human microglia. Our results also attempt to explain the extra-pulmonary dysfunctions observed in COVID-19 cases when active replication of virus is not supported. Since Spike gene and mRNAs have been extensively picked up for vaccine development; the knowledge of host immune response against spike gene and protein holds a great significance. Our study therefore provides novel and relevant insights regarding the impact of Spike gene on shuttling of host microRNAs via exosomes to trigger the neuroinflammation.


Subject(s)
COVID-19/metabolism , Exosomes/metabolism , Interferon-Stimulated Gene Factor 3, gamma Subunit/metabolism , MicroRNAs/metabolism , Microglia/metabolism , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Ubiquitin Thiolesterase/metabolism , COVID-19/genetics , COVID-19/physiopathology , COVID-19/virology , Cell Line , Central Nervous System/immunology , Central Nervous System/physiopathology , Central Nervous System/virology , Endopeptidases/metabolism , Exosomes/genetics , Exosomes/pathology , Humans , Inflammation/immunology , Inflammation/virology , Interferon-beta/metabolism , MicroRNAs/genetics , Microglia/pathology , NF-kappa B/metabolism , Protein Stability , Tumor Necrosis Factor-alpha/metabolism
11.
Signal Transduct Target Ther ; 6(1): 169, 2021 04 24.
Article in English | MEDLINE | ID: covidwho-1199270

ABSTRACT

Neurological manifestations are frequently reported in the COVID-19 patients. Neuromechanism of SARS-CoV-2 remains to be elucidated. In this study, we explored the mechanisms of SARS-CoV-2 neurotropism via our established non-human primate model of COVID-19. In rhesus monkey, SARS-CoV-2 invades the CNS primarily via the olfactory bulb. Thereafter, viruses rapidly spread to functional areas of the central nervous system, such as hippocampus, thalamus, and medulla oblongata. The infection of SARS-CoV-2 induces the inflammation possibly by targeting neurons, microglia, and astrocytes in the CNS. Consistently, SARS-CoV-2 infects neuro-derived SK-N-SH, glial-derived U251, and brain microvascular endothelial cells in vitro. To our knowledge, this is the first experimental evidence of SARS-CoV-2 neuroinvasion in the NHP model, which provides important insights into the CNS-related pathogenesis of SARS-CoV-2.


Subject(s)
Brain Diseases/metabolism , Brain/metabolism , COVID-19/metabolism , Olfactory Bulb/metabolism , SARS-CoV-2/metabolism , Animals , Astrocytes/metabolism , Astrocytes/pathology , Astrocytes/virology , Brain/pathology , Brain/virology , Brain Diseases/pathology , Brain Diseases/virology , COVID-19/pathology , Disease Models, Animal , Humans , Macaca mulatta , Microglia/metabolism , Microglia/pathology , Microglia/virology , Neurons/metabolism , Neurons/pathology , Neurons/virology , Olfactory Bulb/pathology , Olfactory Bulb/virology
12.
Oxid Med Cell Longev ; 2021: 8841911, 2021.
Article in English | MEDLINE | ID: covidwho-1156027

ABSTRACT

Despite the international scientific community's commitment to improve clinical knowledge about coronavirus disease 2019 (COVID-19), knowledge regarding molecular details remains limited. In this review, we discuss hypoxia's potential role in the pathogenesis of the maladaptive immune reaction against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The state of infection, with serious respiratory dysfunction, causes tissues to become hypoxic due to a discrepancy between cellular O2 uptake and consumption similar to that seen within tumor tissue during the progression of numerous solid cancers. In this context, the heterogeneous clinical behavior and the multiorgan deterioration of COVID-19 are discussed as a function of the upregulated expression of the hypoxia-inducible factor-1 (HIF-1) and of the metabolic reprogramming associated with HIF-1 and with a proinflammatory innate immune response activation, independent of the increase in the viral load of SARS-CoV-2. Possible pharmacological strategies targeting O2 aimed to improve prognosis are suggested.


Subject(s)
COVID-19/metabolism , COVID-19/pathology , Cell Polarity , Hypoxia-Inducible Factor 1/metabolism , Macrophages/metabolism , Microglia/metabolism , Warburg Effect, Oncologic , COVID-19/immunology , COVID-19/virology , Humans , SARS-CoV-2/physiology
13.
Cells ; 10(2)2021 01 30.
Article in English | MEDLINE | ID: covidwho-1069793

ABSTRACT

Systemic infection is an important risk factor for the development cognitive impairment and neurodegeneration in older people. Animal experiments show that systemic challenges with live bacteria cause a neuro-inflammatory response, but the effect of age on this response in these models is unknown. Young (2 months) and middle-aged mice (13-14 months) were intraperitoneally challenged with live Escherichia coli (E. coli) or saline. The mice were sacrificed at 2, 3 and 7 days after inoculation; for all time points, the mice were treated with ceftriaxone (an antimicrobial drug) at 12 and 24 h after inoculation. Microglial response was monitored by immunohistochemical staining with an ionized calcium-binding adaptor molecule 1 (Iba-1) antibody and flow cytometry, and inflammatory response by mRNA expression of pro- and anti-inflammatory mediators. We observed an increased microglial cell number and moderate morphologically activated microglial cells in middle-aged mice, as compared to young mice, after intraperitoneal challenge with live E. coli. Flow cytometry of microglial cells showed higher CD45 and CD11b expressions in middle-aged infected mice compared to young infected mice. The brain expression levels of pro-inflammatory genes were higher in middle-aged than in young infected mice, while middle-aged infected mice had similar expression levels of these genes in the systemic compartment. We conclude that systemic challenge with live bacteria causes an age-dependent neuro-inflammatory and microglial response. Our data show signs of an age-dependent disconnection of the inflammatory transcriptional signature between the brain and the systemic compartment.


Subject(s)
Escherichia coli/metabolism , Microglia/metabolism , Aging , Animals , Disease Models, Animal , Humans , Male , Mice
14.
Brain Behav Immun ; 91: 740-755, 2021 01.
Article in English | MEDLINE | ID: covidwho-1064860

ABSTRACT

Central nervous system (CNS) innate immunity plays essential roles in infections, neurodegenerative diseases, and brain or spinal cord injuries. Astrocytes and microglia are the principal cells that mediate innate immunity in the CNS. Pattern recognition receptors (PRRs), expressed by astrocytes and microglia, sense pathogen-derived or endogenous ligands released by damaged cells and initiate the innate immune response. Toll-like receptors (TLRs) are a well-characterized family of PRRs. The contribution of microglial TLR signaling to CNS pathology has been extensively investigated. Even though astrocytes assume a wide variety of key functions, information about the role of astroglial TLRs in CNS disease and injuries is limited. Because astrocytes display heterogeneity and exhibit phenotypic plasticity depending on the effectors present in the local milieu, they can exert both detrimental and beneficial effects. TLRs are modulators of these paradoxical astroglial properties. The goal of the current review is to highlight the essential roles played by astroglial TLRs in CNS infections, injuries and diseases. We discuss the contribution of astroglial TLRs to host defense as well as the dissemination of viral and bacterial infections in the CNS. We examine the link between astroglial TLRs and the pathogenesis of neurodegenerative diseases and present evidence showing the pivotal influence of astroglial TLR signaling on sterile inflammation in CNS injury. Finally, we define the research questions and areas that warrant further investigations in the context of astrocytes, TLRs, and CNS dysfunction.


Subject(s)
Astrocytes/metabolism , Neurodegenerative Diseases/physiopathology , Toll-Like Receptors/physiology , Animals , Astrocytes/physiology , Brain/metabolism , Central Nervous System/immunology , Central Nervous System/metabolism , Central Nervous System Diseases/immunology , Central Nervous System Infections/pathology , Encephalitis/immunology , Humans , Immunity, Innate/physiology , Microglia/metabolism , Neurodegenerative Diseases/metabolism , Neurons/metabolism , Receptors, Pattern Recognition/immunology , Signal Transduction , Spinal Cord/pathology , Spinal Cord Injuries/pathology , Toll-Like Receptors/metabolism
15.
PLoS Pathog ; 16(11): e1009034, 2020 11.
Article in English | MEDLINE | ID: covidwho-950851

ABSTRACT

The interferon-induced tetratricopeptide repeat protein (Ifit2) protects mice from lethal neurotropic viruses. Neurotropic coronavirus MHV-RSA59 infection of Ifit2-/- mice caused pronounced morbidity and mortality accompanied by rampant virus replication and spread throughout the brain. In spite of the higher virus load, induction of many cytokines and chemokines in the brains of infected Ifit2-/- mice were similar to that in wild-type mice. In contrast, infected Ifit2-/- mice revealed significantly impaired microglial activation as well as reduced recruitment of NK1.1 T cells and CD4 T cells to the brain, possibly contributing to the lack of viral clearance. These two deficiencies were associated with a lower level of microglial expression of CX3CR1, the receptor of the CX3CL1 (Fractalkine) chemokine, which plays a critical role in both microglial activation and leukocyte recruitment. The above results uncovered a new potential role of an interferon-induced protein in immune protection.


Subject(s)
Apoptosis Regulatory Proteins/metabolism , Cell Movement/immunology , Coronavirus Infections/virology , Leukocytes/virology , Murine hepatitis virus/pathogenicity , RNA-Binding Proteins/metabolism , Virus Replication/immunology , Animals , Apoptosis Regulatory Proteins/deficiency , Coronavirus Infections/immunology , Cytokines/metabolism , Interferons/metabolism , Leukocytes/cytology , Leukocytes/metabolism , Mice, Inbred C57BL , Microglia/metabolism , Murine hepatitis virus/metabolism
16.
J Virol ; 94(20)2020 09 29.
Article in English | MEDLINE | ID: covidwho-840609

ABSTRACT

Alpha/beta interferon (IFN-α/ß) signaling through the IFN-α/ß receptor (IFNAR) is essential to limit virus dissemination throughout the central nervous system (CNS) following many neurotropic virus infections. However, the distinct expression patterns of factors associated with the IFN-α/ß pathway in different CNS resident cell populations implicate complex cooperative pathways in IFN-α/ß induction and responsiveness. Here we show that mice devoid of IFNAR1 signaling in calcium/calmodulin-dependent protein kinase II alpha (CaMKIIα) expressing neurons (CaMKIIcre:IFNARfl/fl mice) infected with a mildly pathogenic neurotropic coronavirus (mouse hepatitis virus A59 strain [MHV-A59]) developed severe encephalomyelitis with hind-limb paralysis and succumbed within 7 days. Increased virus spread in CaMKIIcre:IFNARfl/fl mice compared to IFNARfl/fl mice affected neurons not only in the forebrain but also in the mid-hind brain and spinal cords but excluded the cerebellum. Infection was also increased in glia. The lack of viral control in CaMKIIcre:IFNARfl/fl relative to control mice coincided with sustained Cxcl1 and Ccl2 mRNAs but a decrease in mRNA levels of IFNα/ß pathway genes as well as Il6, Tnf, and Il1ß between days 4 and 6 postinfection (p.i.). T cell accumulation and IFN-γ production, an essential component of virus control, were not altered. However, IFN-γ responsiveness was impaired in microglia/macrophages irrespective of similar pSTAT1 nuclear translocation as in infected controls. The results reveal how perturbation of IFN-α/ß signaling in neurons can worsen disease course and disrupt complex interactions between the IFN-α/ß and IFN-γ pathways in achieving optimal antiviral responses.IMPORTANCE IFN-α/ß induction limits CNS viral spread by establishing an antiviral state, but also promotes blood brain barrier integrity, adaptive immunity, and activation of microglia/macrophages. However, the extent to which glial or neuronal signaling contributes to these diverse IFN-α/ß functions is poorly understood. Using a neurotropic mouse hepatitis virus encephalomyelitis model, this study demonstrated an essential role of IFN-α/ß receptor 1 (IFNAR1) specifically in neurons to control virus spread, regulate IFN-γ signaling, and prevent acute mortality. The results support the notion that effective neuronal IFNAR1 signaling compensates for their low basal expression of genes in the IFN-α/ß pathway compared to glia. The data further highlight the importance of tightly regulated communication between the IFN-α/ß and IFN-γ signaling pathways to optimize antiviral IFN-γ activity.


Subject(s)
Central Nervous System/virology , Interferon Type I/metabolism , Interferon-gamma/metabolism , Macrophages/metabolism , Microglia/metabolism , Neurons/metabolism , Signal Transduction , Animals , Calcium-Calmodulin-Dependent Protein Kinase Type 2/genetics , Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism , Central Nervous System/immunology , Coronavirus Infections/immunology , Coronavirus Infections/virology , Disease Models, Animal , Encephalomyelitis/immunology , Encephalomyelitis/virology , Macrophages/virology , Mice , Mice, Mutant Strains , Microglia/virology , Murine hepatitis virus/physiology , Neurons/virology , Neutrophil Infiltration , Receptor, Interferon alpha-beta/deficiency , Receptor, Interferon alpha-beta/genetics , Receptor, Interferon alpha-beta/metabolism , Virus Replication
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