Immune Response In Central Nervous System Research Articles

Polyomavirus Wakes Up and Chooses Neurovirulence.

JC polyomavirus (JCPyV) is a human-specific polyomavirus that establishes a silent lifelong infection in multiple peripheral organs, predominantly those of the urinary tract, of immunocompetent individuals. In immunocompromised settings, however, JCPyV can infiltrate the central nervous system (CNS), where it causes several encephalopathies of high morbidity and mortality. JCPyV-induced progressive multifocal leukoencephalopathy (PML), a devastating demyelinating brain disease, was an AIDS-defining illness before antiretroviral therapy that has "reemerged" as a complication of immunomodulating and chemotherapeutic agents. No effective anti-polyomavirus therapeutics are currently available. How depressed immune status sets the stage for JCPyV resurgence in the urinary tract, how the virus evades pre-existing antiviral antibodies to become viremic, and where/how it enters the CNS are incompletely understood. Addressing these questions requires a tractable animal model of JCPyV CNS infection. Although no animal model can replicate all aspects of any human disease, mouse polyomavirus (MuPyV) in mice and JCPyV in humans share key features of peripheral and CNS infection and antiviral immunity. In this review, we discuss the evidence suggesting how JCPyV migrates from the periphery to the CNS, innate and adaptive immune responses to polyomavirus infection, and how the MuPyV-mouse model provides insights into the pathogenesis of JCPyV CNS disease.

Neuroinflammation and neuroimmunology in Alzheimer's disease: The role of T‐lymphocytes in Alzheimer's disease

AbstractAlzheimer's disease (AD) is the leading cause of dementia, with the number of patients with AD expected to double in the next quarter‐century. Brain deposition of amyloid‐β (Aβ) and tau proteins is a necessary but insufficient condition for AD pathogenesis. There is also growing evidence to suggest that chronic neuroinflammation due to excessive microglial activation and astrocyte dysfunction exacerbates the pathophysiology of AD, but the factors that disrupt these homeostatic processes remain unclear. Research into AD pathophysiology has shown interest in the changes in adaptive T‐cells, which play a pivotal role in immunity. The immune alterations in the peripheral circulation and increased blood–brain‐barrier permeability observed in patients with AD, even in the initial stages of the disease, require investigation of the immune mechanisms resulting from T‐cell infiltration into the central nervous system (CNS) during disease initiation and exacerbation. Since T‐cells play a two‐faceted role in the CNS immune response, including pathogenic and neuroprotective roles, the role of T‐cells in AD has been debated. Memory T‐cells reside in the brain and communicate with glial cells and neurons. In this review, the role of immune responses in AD is discussed, focusing on the contribution of T‐cells.

Endothelial cell-derived oxysterol ablation attenuates experimental autoimmune encephalomyelitis.

The vasculature is a key regulator of leukocyte trafficking into the central nervous system (CNS) during inflammatory diseases including multiple sclerosis (MS). However, the impact of endothelial-derived factors on CNS immune responses remains unknown. Bioactive lipids, in particular oxysterols downstream of Cholesterol-25-hydroxylase (Ch25h), promote neuroinflammation but their functions in the CNS are not well-understood. Using floxed-reporter Ch25h knock-in mice, we trace Ch25h expression to CNS endothelial cells (ECs) and myeloid cells and demonstrate that Ch25h ablation specifically from ECs attenuates experimental autoimmune encephalomyelitis (EAE). Mechanistically, inflamed Ch25h-deficient CNS ECs display altered lipid metabolism favoring polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) expansion, which suppresses encephalitogenic Tlymphocyte proliferation. Additionally, endothelial Ch25h-deficiency combined with immature neutrophil mobilization into the blood circulation nearly completely protects mice from EAE. Our findings reveal a central role for CNS endothelial Ch25h in promoting neuroinflammation by inhibiting the expansion of immunosuppressive myeloid cell populations.

2348. Distinct cerebrospinal fluid immune proteins mark neurosyphilis

Abstract Background Neurosyphilis (NS) is increasing in prevalence in the U.S. but remains challenging to diagnose, particularly in asymptomatic cases. Uncovering central nervous system (CNS) specific immune pathways may shed light on disease pathogenesis and potential biomarkers. Methods Paired cerebrospinal fluid and blood were collected from participants with syphilis without neurological symptoms from 2013–2019. Participants were categorized as NS if CSF VDRL was positive and matched by RPR and date of enrollment to participants without neurosyphilis (non-NS), defined by VDRL negative and CSF WBC < 5/uL. Paired CSF and plasma were run on a 71-plex chemokine/cytokine array, high-sensitivity (SIMOA) ELISA for markers of neuronal and astrocyte injury, and ELISA for neopterin, a marker of intrathecal macrophage/microglial activation. Comparisons between NS and non-NS were made using T-tests and Wilcoxon rank-sum tests, with p-values adjusted (FDR) for multiple comparisons. Results 24 participants were enrolled with characteristics as in Table 1. HIV status, age, race/ethnicity, and plasma RPR values did not significantly differ by group. Six cytokines were significantly (p< 0.05, FDR < 0.10) different in the CSF in NS compared to non-NS, including MIG/CXCL9, IP-10/CXCL10, macrophage-derive-chemokine (MDC), IL-8/CXCL8 and BCA-1/CXCL13, which was previously recognized as elevated in NS (Figure 1B). Neopterin, but no neuronal or astrocyte markers, was elevated in the CSF of NS versus non-NS (p < 0.001) (Figure 1A). After adjusting for multiple comparisons, there were no significant differences between markers in plasma of NS vs non-NS. Differences between NS and non-NS groups were not affected by HIV status. Conclusion There is a distinct and compartmentalized CNS immune response occurring in individuals with NS, as indicated by elevated markers of CNS inflammation and of key chemoattractants, the CXC family of proteins. Elevation of neopterin, but not neuronal injury markers suggest asymptomatic disease elicits an immune response without incurring neuronal damage. These immune biomarkers can provide insight into neuroinflammatory processes during asymptomatic NS and should be explored as potential CSF biomarkers of NS. Disclosures Magnus Gisslen, MD, PhD, Amgen: Honoraria|AstraZeneca: Advisor/Consultant|AstraZeneca: DSMB membership|Biogen: Honoraria|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Honoraria|GlaxoSmithKline/ViiV: Advisor/Consultant|GlaxoSmithKline/ViiV: Honoraria|MSD: Advisor/Consultant|MSD: Honoraria|Novo Nordic: Honoraria|Novocure: Honoraria|Pfizer: Advisor/Consultant|Pfizer: Honoraria|Sanofi: Honoraria.

Single-cell transcriptomics reveals functionally specialized vascular endothelium in brain.

The blood-brain barrier (BBB) limits the entry of leukocytes and potentially harmful substances from the circulation into the central nervous system (CNS). While BBB defects are a hallmark of many neurological disorders, the cellular heterogeneity at the neurovascular interface and the mechanisms governing neuroinflammation are not fully understood. Through single cell RNA sequencing of non-neuronal cell populations of the murine cerebral cortex during development, adulthood, ageing and neuroinflammation, we identify reactive endothelial venules (REVs), a compartment of specialised post-capillary endothelial cells (ECs) that are characterized by consistent expression of cell adhesion molecules, preferential leukocyte transmigration, association with perivascular macrophage populations, and endothelial activation initiating CNS immune responses. Our results provide novel insights into the heterogeneity of the cerebral vasculature and a useful resource for the molecular alterations associated with neuroinflammation and ageing.

Cocaine Self-Administration Influences Central Nervous System Immune Responses in Male HIV-1 Transgenic Rats.

Cocaine use increases the neurotoxic severity of human immunodeficiency virus-1 (HIV-1) infection and the development of HIV-associated neurocognitive disorders (HAND). Among the studied cellular mechanisms promoting neurotoxicity in HIV-1 and cocaine use, central nervous system (CNS) immunity, such as neuroimmune signaling and reduced antiviral activity, are risk determinants; however, concrete evidence remains elusive. In the present study, we tested the hypothesis that cocaine self-administration by transgenic HIV-1 (HIV-1Tg) rats promotes CNS inflammation. To test this hypothesis, we measured cytokine, chemokine, and growth factor protein levels in the frontal cortex (fCTX) and caudal striatum (cSTR). Our results demonstrated that cocaine self-administration significantly increased fCTX inflammation in HIV-1Tg rats, but not in the cSTR. Accordingly, we postulate that cocaine synergizes with HIV-1 proteins to increase neuroinflammation in a region-selective manner, including the fCTX. Given the fCTX role in cognition, this interaction may contribute to the hyperimmunity and reduced antiviral activity associated with cocaine-mediated enhancement of HAND.

Viral Antigen and Inflammatory Biomarkers in Cerebrospinal Fluid in Patients With COVID-19 Infection and Neurologic Symptoms Compared With Control Participants Without Infection or Neurologic Symptoms

Neurologic symptoms are common in COVID-19, but the central nervous system (CNS) pathogenesis is unclear, and viral RNA is rarely detected in cerebrospinal fluid (CSF). To measure viral antigen and inflammatory biomarkers in CSF in relation to neurologic symptoms and disease severity. This cross-sectional study was performed from March 1, 2020, to June 30, 2021, in patients 18 years or older who were admitted to Sahlgrenska University Hospital, Gothenburg, Sweden, with COVID-19. All patients had CSF samples taken because of neurologic symptoms or within a study protocol. Healthy volunteer and prepandemic control groups were included. SARS-CoV-2 infection. Outcomes included CSF SARS-CoV-2 nucleocapsid antigen (N-Ag) using an ultrasensitive antigen capture immunoassay platform and CSF biomarkers of immune activation (neopterin, β2-microglobulin, and cytokines) and neuronal injury (neurofilament light protein [NfL]). Forty-four patients (median [IQR] age, 57 [48-69] years; 30 [68%] male; 26 with moderate COVID-19 and 18 with severe COVID-19 based on the World Health Organization Clinical Progression Scale), 10 healthy controls (median [IQR] age, 58 [54-60] years; 5 [50%] male), and 41 patient controls (COVID negative without evidence of CNS infection) (median [IQR] age, 59 [49-70] years; 19 [46%] male) were included in the study. Twenty-one patients were neuroasymptomatic and 23 were neurosymptomatic (21 with encephalopathy). In 31 of 35 patients for whom data were available (89%), CSF N-Ag was detected; viral RNA test results were negative in all. Nucleocapsid antigen was significantly correlated with CSF neopterin (r = 0.38; P = .03) and interferon γ (r = 0.42; P = .01). No differences in CSF N-Ag concentrations were found between patient groups. Patients had markedly increased CSF neopterin, β2-microglobulin, interleukin (IL) 2, IL-6, IL-10, and tumor necrosis factor α compared with controls. Neurosymptomatic patients had significantly higher median (IQR) CSF interferon γ (86 [47-172] vs 21 [17-81] fg/mL; P = .03) and had a significantly higher inflammatory biomarker profile using principal component analysis compared with neuroasymptomatic patients (0.54; 95% CI, 0.03-1.05; P = .04). Age-adjusted median (IQR) CSF NfL concentrations were higher in patients compared with controls (960 [673-1307] vs 618 [489-786] ng/L; P = .002). No differences were seen in any CSF biomarkers in moderate compared with severe disease. In this study of Swedish adults with COVID-19 infection and neurologic symptoms, compared with control participants, viral antigen was detectable in CSF and correlated with CNS immune activation. Patients with COVID-19 had signs of neuroaxonal injury, and neurosymptomatic patients had a more marked inflammatory profile that could not be attributed to differences in COVID-19 severity. These results highlight the clinical relevance of neurologic symptoms and suggest that viral components can contribute to CNS immune responses without direct viral invasion.

Tumor Immune Microenvironment of Brain Metastases: Toward Unlocking Antitumor Immunity.

There is an urgent need to improve patient selection for and clinical activity of ICIs in patients with cancer with concomitant BrM. Increased understanding of the unique immunobiologic principles that govern response to ICIs in the CNS is critical toward identifying targets in the tumor microenvironment that may potentiate antitumor immunity.

Infections in the Developing Brain: The Role of the Neuro-Immune Axis.

Central nervous system (CNS) infections occur more commonly in young children than in adults and pose unique challenges in the developing brain. This review builds on the distinct vulnerabilities in children's peripheral immune system (outlined in part 1 of this review series) and focuses on how the developing brain responds once a CNS infection occurs. Although the protective blood-brain barrier (BBB) matures early, pathogens enter the CNS and initiate a localized innate immune response with release of cytokines and chemokines to recruit peripheral immune cells that contribute to the inflammatory cascade. This immune response is initiated by the resident brain cells, microglia and astrocytes, which are not only integral to fighting the infection but also have important roles during normal brain development. Additionally, cytokines and other immune mediators such as matrix metalloproteinases from neurons, glia, and endothelial cells not only play a role in BBB permeability and peripheral cell recruitment, but also in brain maturation. Consequently, these immune modulators and the activation of microglia and astrocytes during infection adversely impact normal neurodevelopment. Perturbations to normal brain development manifest as neurodevelopmental and neurocognitive impairments common among children who survive CNS infections and are often permanent. In part 2 of the review series, we broadly summarize the unique challenges CNS infections create in a developing brain and explore the interaction of regulators of neurodevelopment and CNS immune response as part of the neuro-immune axis.

Vascular inflammation in the central nervous system.

Vascular inflammation in the central nervous system.

Expression of antimicrobial host defence peptides in the central nervous system during health and disease.

Antimicrobial host defence peptides (HDP) are critical for the first line of defence against bacterial, viral, and fungal pathogens. Over the past decade we have become more aware that, in addition to their antimicrobial roles, they also possess the potent immunomodulatory capacity. This includes chemoattracting immune cells, activating dendritic cells and macrophages, and altering T-cell differentiation. Most examinations of their immunomodulatory roles have focused on tissues in which they are very abundant, such as the intestine and the inflamed skin. However, HDP have now been detected in the brain and the spinal cord during a number of conditions. We propose that their presence in the central nervous system (CNS) during homeostasis, infection, and neurodegenerative disease has the potential to contribute to immunosurveillance, alter host responses and skew developing immunity. Here, we review the evidence for HDP expression and function in the CNS in health and disease. We describe how a wide range of HDP are expressed in the CNS of humans, rodents, birds, and fish, suggesting a conserved role in protecting the brain from pathogens, with evidence of production by resident CNS cells. We highlight differences in methodology used and how this may have resulted in the immunomodulatory roles of HDP being overlooked. Finally, we discuss what HDP expression may mean for CNS immune responses.

The Impact of Ageing on the CNS Immune Response in Alzheimer's Disease.

Alzheimer’s Disease (AD) is a progressive neurodegenerative disease strongly associated with increasing age. Neuroinflammation and the accumulation of amyloid protein are amongst the hallmarks of this disease and most translational research to date has focused on targeting these two processes. However, the exact etiology of AD remains to be fully elucidated. When compared alongside, the immune response in AD closely resembles the central nervous system (CNS) immune changes seen in elderly individuals. It is possible that AD is a pathological consequence of an aged immune system secondary to chronic stimulation by a previous or ongoing insult. Pathological changes like amyloid accumulation and neuronal cell death may reflect this process of immunosenescence as the CNS immune system fails to maintain homeostasis in the CNS. It is likely that future treatments designed to modulate the aged immune system may prove beneficial in altering the disease course. The development of new tests for appropriate biomarkers would also be essential in screening for patients most likely to benefit from such treatments.

Safic-Alcan extends distribution agreement with PMC Organometallix

A fungal central nervous system (CNS) infection develops after it spreads from somewhere else in the body to the brain or spinal cord. Fungal CNS infection is associated with immune system impairment, some health conditions including the use of the medications (e.g., steroids), surgical procedures, Human immunodeficiency virus (HIV) infection, organ transplantation, end stage renal disease on hemodialysis, status post chemotherapy, neutropenia, and pre-term babies. Fungi involved in brain infection include yeasts such as Cryptococcus sp., Candida sp., and Trichosporon spp.; Moniliaceous molds including Aspergillus sp., Fusarium sp. and Scedosporium sp., Mucoromycetes such as Mucor spp. and Rhizopus spp., dimorphic fungi including Blastomyces sp., Coccidioides spp. and Histoplasma sp., and dematiaceous fungi such as Cladophialophora sp. and Exophiala sp. In this article, we will focus on the fungal meningitis and encephalitis. We will also explain fungal invasion mechanisms, the CNS immune response to the fungal infection, and clinical consequences.

Regulation of IFN-Is by MEF2D Promotes Inflammatory Homeostasis in Microglia

BackgroundMicroglia play an essential role in the central nervous system immune response. The transcription factor myocyte enhancer factor-2 D (MEF2D) is known to participate in stress regulation in various cell types and is easily activated in microglia. MEF2D has been shown to transcriptionally regulate several cytokine genes in immune cells and directly regulates the inflammatory response, suggesting that MEF2D may act as a key stimulus response regulator of microglia and is involved in the regulation of brain microhomeostasis. To uncover the molecular mechanism of MEF2D in the inflammatory system, in the present study, we investigated the global effect of MEF2D in activated microglia and explored its potential regulatory network.MethodsExperiments with a recombinant lentiviral vector containing either shRNA or overexpressing MEF2D were performed in the murine microglial BV2 cell line. Transcriptome sequencing and global gene expression patterns were analysed in lipopolysaccharide-stimulated shMEF2D BV2 cells. Pro- and anti-inflammatory factors were assessed by Western blot, qPCR or ELISA, and microglial activity was assessed by phagocytosis and morphologic analysis. The direct binding of MEF2D to the promoter region of interferon regulatory factor 7 (IRF7) was tested by ChIP-qPCR. The interferon-stimulated genes (ISGs) were tested by qPCR.ResultsMEF2D actively participated in the inflammatory response of BV2 microglial cells. Stably expressed RNAi-induced silencing of MEF2D disrupted the microglial immune balance in two ways: (1) the expression of proinflammatory factors, such as NLRP3, IL-1β, and iNOS was promoted; and (2) the type-I interferon signalling pathway was markedly inhibited by directly modulating IRF7 transcription. In contrast, overexpression of MEF2D significantly reduced the expression of NLRP3 and iNOS under LPS stimulation and alleviated the level of immune stress in microglia.ConclusionThese findings demonstrate that MEF2D plays an important role in regulating inflammatory homeostasis partly through transcriptional regulation of the type-I interferon signalling pathway.

Emerging Role of PD-1 in the Central Nervous System and Brain Diseases.

Programmed cell death protein 1 (PD-1) is an immune checkpoint modulator and a major target of immunotherapy as anti-PD-1 monoclonal antibodies have demonstrated remarkable efficacy in cancer treatment. Accumulating evidence suggests an important role of PD-1 in the central nervous system (CNS). PD-1 has been implicated in CNS disorders such as brain tumors, Alzheimer's disease, ischemic stroke, spinal cord injury, multiple sclerosis, cognitive function, and pain. PD-1 signaling suppresses the CNS immune response via resident microglia and infiltrating peripheral immune cells. Notably, PD-1 is also widely expressed in neurons and suppresses neuronal activity via downstream Src homology 2 domain-containing protein tyrosine phosphatase 1 and modulation of ion channel function. An improved understanding of PD-1 signaling in the cross-talk between glial cells, neurons, and peripheral immune cells in the CNS will shed light on immunomodulation, neuromodulation, and novel strategies for treating brain diseases.

Selenization of S. cerevisiae increases its protective potential in experimental autoimmune encephalomyelitis by triggering an intestinal immunomodulatory loop

Multiple sclerosis is an autoimmune disease that affects the myelinated central nervous system (CNS) neurons and triggers physical and cognitive disabilities. Conventional therapy is based on disease-modifying drugs that control disease severity but can also be deleterious. Complementary medicines have been adopted and evidence indicates that yeast supplements can improve symptoms mainly by modulating the immune response. In this investigation, we evaluated the therapeutic potential of Saccharomyces cerevisiae and its selenized derivative (Selemax) in experimental autoimmune encephalomyelitis (EAE). Female C57BL/6 mice submitted to EAE induction were orally supplemented with these yeasts by gavage from day 0 to day 14 after EAE induction. Both supplements determined significant reduction in clinical signs concomitantly with diminished Th1 immune response in CNS, increased proportion of Foxp3+ lymphocytes in inguinal and mesenteric lymph nodes and increased microbiota diversity. However, Selemax was more effective clinically and immunologically; it reduced disease prevalence more sharply, increased the proportion of CD103+ dendritic cells expressing high levels of PD-L1 in mesenteric lymph nodes and reduced the intestinal inflammatory process more strongly than S. cerevisiae. These results suggest a clear gut-brain axis modulation by selenized S. cerevisiae and suggest their inclusion in clinical trials.

IFN-I Independent Antiviral Immune Response to Vesicular Stomatitis Virus Challenge in Mouse Brain.

Type I interferon (IFN-I) plays a pivotal role during viral infection response in the central nervous system (CNS). The IFN-I can orchestrate and regulate most of the innate immune gene expression and myeloid cell dynamics following a noncytopathic virus infection. However, the role of IFN-I in the CNS against viral encephalitis is not entirely clear. Here we have implemented the combination of global differential gene expression profiling followed by bioinformatics analysis to decipher the CNS immune response in the presence and absence of the IFN-I signaling. We observed that vesicular stomatitis virus (VSV) infection induced 281 gene changes in wild-type (WT) mice primarily associated with IFN-I signaling. This was accompanied by an increase in antiviral response through leukocyte vascular patrolling and leukocyte influx along with the expression of potent antiviral factors. Surprisingly, in the absence of the IFN-I signaling (IFNAR−/− mice), a significantly higher (1357) number of genes showed differential expression compared to the WT mice. Critical candidates such as IFN-γ, CCL5, CXCL10, and IRF1, which are responsible for the recruitment of the patrolling leukocytes, are also upregulated in the absence of IFN-I signaling. The computational network analysis suggests the presence of the IFN-I independent pathway that compensates for the lack of IFN-I signaling in the brain. The analysis shows that TNF-α is connected maximally to the networked candidates, thus emerging as a key regulator of gene expression and recruitment of myeloid cells to mount antiviral action. This pathway could potentiate IFN-γ release; thereby, synergistically activating IRF1-dependent ISG expression and antiviral response.

Peripheral and Central Nervous System Immune Response Crosstalk in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by muscle weakness due to the degeneration of the upper and lower motor neurons. Neuroinflammation is known as a prominent pathological feature of ALS. Although neuroinflammation cannot trigger ALS, activated central nervous system (CNS) microglia and astrocytes, proinflammatory periphery monocytes/macrophages and T lymphocytes, and infiltrated monocytes/macrophages and T lymphocytes, as well as the immunoreactive molecules they release, are closely related to disease progression. The crosstalk between the peripheral and CNS immune components mentioned above significantly correlates with survival in patients with ALS. This review provides an update on the role of this crosstalk between the CNS and peripheral immune responses in ALS. Additionally, we discuss changes in the composition of gut microbiota because these can directly or indirectly influence this crosstalk. These recent advances may well provide innovative ways for targeting the molecules associated with this crosstalk and breaking the current treatment impasse in ALS.

Neuroinflammation in Alzheimer’s Disease: Friend or Foe?

Neuroinflammation is part of the complex immune response within the central nervous system (CNS), whose details have been partially elucidated. The CNS immune response involves elements carried from the periphery and resident elements, mainly represented by glial cells. These cells drive neuroinflammation, which can be roughly defined as an articulated physiological response characterized by the production of a plethora of inflammatory mediators that alter the microenvironment. Growing evidence shows roles for neuroinflammation in the aging brain both in healthy and pathological conditions, including Alzheimer’s disease (AD). AD is a multifactorial neurodegenerative disease of the brain, characterized, at the molecular level, by deposits of beta‐amyloid peptides in the extracellular space and of neurofibrillary tangles inside neurons. Together with abnormal protein deposits, it is now established that neuroinflammation represents the third hallmark found in AD patients’ brains. Many scientists agree that the neuroinflammatory process begins at the earliest phase of AD, bringing both positive and negative consequences. Indeed, the brain immune system recognizes the abnormal accumulation of proteins as injurious stimuli, so it initiates a physiological reaction to defend the brain that includes activation of glial cells and release of proinflammatory molecules. When these processes are protracted, they may contribute independently to neural dysfunction, cell death, thus fostering AD progression. Based on these considerations, targeting pathological gliosis seems to represent a valuable therapeutic approach. Compounds able to control glial activation with a combination of neuroprotective and anti‐inflammatory effects constitute a pool of possible therapeutic drugs to study. By using different in vitro and in vivo models of AD, I demonstrated the presence of important alterations of cerebral homeostasis caused by glial abnormalities. Obtained results have contributed to clarify the possible consequences of glia activation and of the subsequent neuroinflammation, demonstrating the presence of significant (i) alterations of the cerebral cytoarchitecture, (ii) modifications of cerebral metabolism and (iii) neuronal death. My results support the notion that targeting pathological gliosis may represent a promising and innovative therapeutic approach for several brain diseases. However, the effect of therapeutic interventions targeting glial cells depends on reaching the perfect balance between attenuating the deleterious effects and maintain the beneficial mechanisms of brain defense.Support or Funding InformationThis research was supported by the Italian Ministry of Instruction, University and Research (MIUR) to LS, and the SAPIENZA University of Rome to CS.

Enterovirus and Encephalitis.

Enterovirus-induced infection of the central nervous system (CNS) results in acute inflammation of the brain (encephalitis) and constitutes a significant global burden to human health. These viruses are thought to be highly cytolytic, therefore normal brain function could be greatly compromised following enteroviral infection of the CNS. A further layer of complexity is added by evidence showing that some enteroviruses may establish a persistent infection within the CNS and eventually lead to pathogenesis of certain neurodegenerative disorders. Interestingly, enterovirus encephalitis is particularly common among young children, suggesting a potential causal link between the development of the neuroimmune system and enteroviral neuroinvasion. Although the CNS involvement in enterovirus infections is a relatively rare complication, it represents a serious underlying cause of mortality. Here we review a selection of enteroviruses that infect the CNS and discuss recent advances in the characterization of these enteroviruses with regard to their routes of CNS infection, tropism, virulence, and immune responses.