Anti-SARS-CoV-2 antibodies in the CSF, blood-brain barrier dysfunction, and neurological outcome: Studies in 8 stuporous and comatose patients

Neuropsychiatric complications of coronavirus disease 2019: Mount Sinai Health System cohort study

OBJECTIVE

To describe the frequency of neuropsychiatric complications among hospitalized patients with coronavirus disease 2019 (COVID-19) and their association with pre-existing comorbidities and clinical outcomes.

METHODS

We retrospectively identified all patients hospitalized with COVID-19 within a large multicenter New York City health system between March 15, 2020 and May 17, 2021 and randomly selected a representative cohort for detailed chart review. Clinical data, including the occurrence of neuropsychiatric complications (categorized as either altered mental status [AMS] or other neuropsychiatric complications) and in-hospital mortality, were extracted using an electronic medical record database and individual chart review. Associations between neuropsychiatric complications, comorbidities, laboratory findings, and in-hospital mortality were assessed using multivariate logistic regression.

RESULTS

Our study cohort consisted of 974 patients, the majority were admitted during the first wave of the pandemic. Patients were treated with anticoagulation (88.4%), glucocorticoids (24.8%), and remdesivir (10.5%); 18.6% experienced severe COVID-19 pneumonia (evidenced by ventilator requirement). Neuropsychiatric complications occurred in 58.8% of patients; 39.8% experienced AMS; and 19.0% experienced at least one other complication (seizures in 1.4%, ischemic stroke in 1.6%, hemorrhagic stroke in 1.0%) or symptom (headache in 11.4%, anxiety in 6.8%, ataxia in 6.3%). Higher odds of mortality, which occurred in 22.0%, were associated with AMS, ventilator support, increasing age, and higher serum inflammatory marker levels. Anticoagulant therapy was associated with lower odds of mortality and AMS.

CONCLUSION

Neuropsychiatric complications of COVID-19, especially AMS, were common, varied, and associated with in-hospital mortality in a diverse multicenter cohort at an epicenter of the COVID-19 pandemic.

Alterations in microbiota of patients with COVID-19: implications for therapeutic interventions

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recently caused a global pandemic, resulting in more than 702 million people being infected and over 6.9 million deaths. Patients with coronavirus disease (COVID-19) may suffer from diarrhea, sleep disorders, depression, and even cognitive impairment, which is associated with long COVID during recovery. However, there remains no consensus on effective treatment methods. Studies have found that patients with COVID-19 have alterations in microbiota and their metabolites, particularly in the gut, which may be involved in the regulation of immune responses. Consumption of probiotics may alleviate the discomfort caused by inflammation and oxidative stress. However, the pathophysiological process underlying the alleviation of COVID-19-related symptoms and complications by targeting the microbiota remains unclear. In the current study, we summarize the latest research and evidence on the COVID-19 pandemic, together with symptoms of SARS-CoV-2 and vaccine use, with a focus on the relationship between microbiota alterations and COVID-19-related symptoms and vaccine use. This work provides evidence that probiotic-based interventions may improve COVID-19 symptoms by regulating gut microbiota and systemic immunity. Probiotics may also be used as adjuvants to improve vaccine efficacy.

Investigating the structural network underlying brain-immune interactions using combined histopathology and neuroimaging: a critical review for its relevance in acute and long COVID-19

Current views on immunity support the idea that immunity extends beyond defense functions and is tightly intertwined with several other fields of biology such as virology, microbiology, physiology and ecology. It is also critical for our understanding of autoimmunity and cancer, two topics of great biological relevance and for critical public health considerations such as disease prevention and treatment. Central to this review, the immune system is known to interact intimately with the nervous system and has been recently hypothesized to be involved not only in autonomic and limbic bio-behaviors but also in cognitive function. Herein we review the structural architecture of the brain network involved in immune response. Furthermore, we elaborate upon the implications of inflammatory processes affecting brain-immune interactions as reported recently in pathological conditions due to SARS-Cov-2 virus infection, namely in acute and post-acute COVID-19. Moreover, we discuss how current neuroimaging techniques combined with ad hoc clinical autopsies and histopathological analyses could critically affect the validity of clinical translation in studies of human brain-immune interactions using neuroimaging. Advances in our understanding of brain-immune interactions are expected to translate into novel therapeutic avenues in a vast array of domains including cancer, autoimmune diseases or viral infections such as in acute and post-acute or Long COVID-19.

Neurovascular coupling impairment as a mechanism for cognitive deficits in COVID-19

Components that comprise our brain parenchymal and cerebrovascular structures provide a homeostatic environment for proper neuronal function to ensure normal cognition. Cerebral insults (e.g. ischaemia, microbleeds and infection) alter cellular structures and physiologic processes within the neurovascular unit and contribute to cognitive dysfunction. COVID-19 has posed significant complications during acute and convalescent stages in multiple organ systems, including the brain. Cognitive impairment is a prevalent complication in COVID-19 patients, irrespective of severity of acute SARS-CoV-2 infection. Moreover, overwhelming evidence from in vitro, preclinical and clinical studies has reported SARS-CoV-2-induced pathologies in components of the neurovascular unit that are associated with cognitive impairment. Neurovascular unit disruption alters the neurovascular coupling response, a critical mechanism that regulates cerebromicrovascular blood flow to meet the energetic demands of locally active neurons. Normal cognitive processing is achieved through the neurovascular coupling response and involves the coordinated action of brain parenchymal cells (i.e. neurons and glia) and cerebrovascular cell types (i.e. endothelia, smooth muscle cells and pericytes). However, current work on COVID-19-induced cognitive impairment has yet to investigate disruption of neurovascular coupling as a causal factor. Hence, in this review, we aim to describe SARS-CoV-2's effects on the neurovascular unit and how they can impact neurovascular coupling and contribute to cognitive decline in acute and convalescent stages of the disease. Additionally, we explore potential therapeutic interventions to mitigate COVID-19-induced cognitive impairment. Given the great impact of cognitive impairment associated with COVID-19 on both individuals and public health, the necessity for a coordinated effort from fundamental scientific research to clinical application becomes imperative. This integrated endeavour is crucial for mitigating the cognitive deficits induced by COVID-19 and its subsequent burden in this especially vulnerable population.

COVID-19-associated serum and cerebrospinal fluid cytokines in post- versus para-infectious SARS-CoV-2-related Guillain-Barré syndrome

INTRODUCTION

Guillain-Barré syndrome associated with Coronavirus-2-related severe acute respiratory syndrome (COV-GBS) occurs as para- or post-infectious forms, depending on the timing of disease onset. In these two forms, we aimed to compare the cerebrospinal fluid (CSF) and serum proinflammatory cytokine profiles to evaluate differences that could possibly have co-pathogenic relevance.

MATERIALS AND METHODS

We studied a retrospective cohort of 26 patients with either post-COV-GBS (n = 15), with disease onset occurring > 7 days after SARS-CoV-2 infection, or para-COV-GBS (n = 11), with disease onset 7 days or less. TNF-α, IL-6, and IL-8 were measured in the serum with SimplePlex™ Ella™ immunoassay. In addition to the para-/post-COV-GBS patients, serum levels of these cytokines were determined in those with non-COVID-associated-GBS (NC-GBS; n = 43), paucisymptomatic SARS-CoV-2 infection without GBS (COVID, n = 20), and in healthy volunteers (HV; n = 12). CSF cytokine levels were measured in patients with para-/post-COV-GBS, in those with NC-GBS (n = 29), or with Alzheimer's disease (AD; n = 24).

RESULTS

Serum/CSF cytokine levels did not differ in para- vs post-COV-GBS. We found that SARS-CoV-2 infection raises the serum levels of TNF-α, IL-6, and IL-8, as well as an increase of IL-6 (in serum and CSF) and IL-8 (in CSF) in either NC-GBS or COV-GBS than controls. CSF and serum cytokine levels resulted independent one with another.

CONCLUSIONS

The change of cytokines linked to SARS-CoV-2 in COV-GBS appears to be driven by viral infection, although it has unique characteristics in GBS as such and does not account for cases with para- or post-infectious onset.

SARS-CoV-2 Infection to Premature Neuronal Aging and Neurodegenerative Diseases: Is there any Connection with Hypoxia?

The pandemic of coronavirus disease-2019 (COVID-19), caused by SARS-CoV-2, has become a global concern as it leads to a spectrum of mild to severe symptoms and increases death tolls around the world. Severe COVID-19 results in acute respiratory distress syndrome, hypoxia, and multi- organ dysfunction. However, the long-term effects of post-COVID-19 infection are still unknown. Based on the emerging evidence, there is a high possibility that COVID-19 infection accelerates premature neuronal aging and increases the risk of age-related neurodegenerative diseases in mild to severely infected patients during the post-COVID period. Several studies correlate COVID-19 infection with neuronal effects, though the mechanism through which they contribute to the aggravation of neuroinflammation and neurodegeneration is still under investigation. SARS-CoV-2 predominantly targets pulmonary tissues and interferes with gas exchange, leading to systemic hypoxia. The neurons in the brain require a constant supply of oxygen for their proper functioning, suggesting that they are more vulnerable to any alteration in oxygen saturation level that results in neuronal injury with or without neuroinflammation. We hypothesize that hypoxia is one of the major clinical manifestations of severe SARS-CoV-2 infection; it directly or indirectly contributes to premature neuronal aging, neuroinflammation, and neurodegeneration by altering the expression of various genes responsible for the survival of the cells. This review focuses on the interplay between COVID-19 infection, hypoxia, premature neuronal aging, and neurodegenerative diseases and provides a novel insight into the molecular mechanisms of neurodegeneration.

Microglial Inflammatory Responses to SARS-CoV-2 Infection: A Comprehensive Review

Coronavirus disease 2019 (COVID-19) is primarily a respiratory disease causing a worldwide pandemic in the year of 2019. SARS-CoV-2 is an enveloped, positive-stranded RNA virus that could invade the host through spike protein and exhibits multi-organ effects. The Brain was considered to be a potential target for SARS-CoV-2 infection. Although neuropsychiatric symptoms and cognitive impairments were observed in COVID-19 patients even after recovery the mechanism of action is not well documented. In this review, the contribution of microglia in response to SARS-CoV-2 infection was discussed aiming to design a therapeutic regimen for the management of neuroinflammation and psycho-behavioral alterations. Priming of microglia facilitates the hyper-activation state when it interacts with SARS-CoV-2 known as the 'second hit'. Moreover, the microgliosis produces reactive free radicals and pro-inflammatory cytokines like IL-1β, IFN-γ, and IL-6 which ultimately contribute to a 'cytokine storm', thereby increasing the occurrence of cognitive and neurological dysfunction. It was reported that elevated CCL11 may be responsible for psychiatric disorders and ROS/RNS-induced oxidative stress could promote major depressive disorder (MDD) and phenotypic switching. Additionally, during SARS-CoV-2 infection microglia-CD8+ T cell interaction may have a significant role in neuronal cell death. This cytokine-mediated cellular cross-talking plays a crucial role in pro-inflammatory and anti-inflammatory balance within the COVID-19 patient's brain. Therefore, all these aspects will be taken into consideration for developing novel therapeutic strategies to combat SARS-CoV-2-induced neuroinflammation.

Blood-brain barrier breakdown in COVID-19 ICU survivors: an MRI pilot study

Objectives

Coronavirus disease 2019 (COVID-19) results in severe inflammation at the acute stage. Chronic neuroinflammation and abnormal immunological response have been suggested to be the contributors to neuro-long-COVID, but direct evidence has been scarce. This study aims to determine the integrity of the blood-brain barrier (BBB) in COVID-19 intensive care unit (ICU) survivors using a novel MRI technique.

Methods

COVID-19 ICU survivors (n=7) and age and sex-matched control participants (n=17) were recruited from June 2021 to March 2023. None of the control participants were hospitalized due to COVID-19 infection. The COVID-19 ICU survivors were studied at 98.6 ± 14.9 days after their discharge from ICU. A non-invasive MRI technique was used to assess the BBB permeability to water molecules, in terms of permeability surface area-product (PS) in the units of mL/100 g/min.

Results

PS was significantly higher in COVID-19 ICU survivors (p=0.038) when compared to the controls, with values of 153.1 ± 20.9 mL/100 g/min and 132.5 ± 20.7 mL/100 g/min, respectively. In contrast, there were no significant differences in whole-brain cerebral blood flow (p=0.649) or brain volume (p=0.471) between the groups.

Conclusions

There is preliminary evidence of a chronic BBB breakdown in COVID-19 survivors who had a severe acute infection, suggesting a plausible contributor to neurological long-COVID symptoms.

SARS-CoV-2 and autoantibodies in the cerebrospinal fluid of COVID-19 patients: prospective multicentre cohort study

Disease mechanisms underlying neurological and neuropsychiatric symptoms after coronavirus disease 2019 (COVID-19), termed neuro-COVID, are poorly understood. Investigations of the cerebrospinal fluid (CSF) for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA and antibodies, as well as autoantibodies against neuronal surface antigens, could improve our understanding in that regard. We prospectively collected CSF and blood from patients investigated by lumbar puncture for neurological or neuropsychiatric symptoms during or after COVID-19. Primary outcomes were the presence of (i) SARS-CoV-2 RNA in CSF via polymerase chain reaction (PCR), (ii) SARS-CoV-2 immunoglobulin G (IgG) anti-S receptor-binding-domain antibodies via the Euroimmun and Wantai assays and (iii) IgG autoantibodies against neuronal surface antigens using commercial cell- and tissue-based assays (Euroimmun). Secondary outcomes were (i) routine CSF investigations and (ii) correlation between SARS-CoV-2 antibody levels in CSF with serum levels, blood-brain barrier permeability and peripheral inflammation. We obtained CSF from 38 COVID-19 patients (mean age 56.5 ± 19.2 years, 53% women) who developed neurological and neuropsychiatric symptoms. CSF pleocytosis (>5 cells) was observed in 9/38 patients (23.7%), elevated CSF protein (>0.50 g/L) in 13/38 (34.2%) and elevated CSF/serum albumin ratio in 12/35 (34.3%). PCR for SARS-CoV-2 RNA in CSF was negative in all. SARS-CoV-2 CSF antibodies were detected in 15/34 (44.1%; Euroimmun assay) and 7/31 (22.6%; Wantai assay) individuals, but there were no signs of intrathecal SARS-CoV-2 IgG production. SARS-CoV-2 CSF antibodies were positively correlated with serum levels (R = 0.93, P < 0.001), blood-brain barrier permeability (R = 0.47, P = 0.006), peripheral inflammation (R = 0.51, P = 0.002) and admission to the intensive care unit [odds ratio (OR) 17.65; 95% confidence interval (CI) 1.18-264.96; P = 0.04; n = 15]. Cell-based assays detected weakly positive NMDAR, LGI1 and CASPR2 antibodies in serum of 4/34 (11.8%) patients but not in CSF. The tissue-based assay showed anti-neuronal fluorescence in CSF from one individual, staining for Purkinje cells. In summary, whereas we did not detect active SARS-CoV-2 infection in the CSF, SARS-CoV-2 antibodies were prevalent. The absence of intrathecal antibody production points towards blood-brain barrier impairment as the origin of CSF SARS-CoV-2 antibodies. In contrast, CSF autoantibodies against neuronal surface antigens were rare. There was no evidence for a clinical correlate of these antibodies. We conclude that, rather than specific autoimmune neuronal injury, non-specific effects of critical illness including an impaired blood-brain barrier are more likely to contribute to neuro-COVID.

Neurologic sequelae of COVID-19 are determined by immunologic imprinting from previous coronaviruses

Coronavirus disease 2019 (COVID-19), which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global public health emergency. Although SARS-CoV-2 is primarily a respiratory pathogen, extra-respiratory organs, including the CNS, can also be affected. Neurologic symptoms have been observed not only during acute SARS-CoV-2 infection, but also at distance from respiratory disease, also known as long-COVID or neurological post-acute sequelae of COVID-19 (neuroPASC). The pathogenesis of neuroPASC is not well understood, but hypotheses include SARS-CoV-2-induced immune dysfunctions, hormonal dysregulations and persistence of SARS-CoV-2 reservoirs. In this prospective cohort study, we used a high throughput systems serology approach to dissect the humoral response to SARS-CoV-2 (and other common coronaviruses: 229E, HKU1, NL63 and OC43) in the serum and CSF from 112 infected individuals who developed (n = 18) or did not develop (n = 94) neuroPASC. Unique SARS-CoV-2 humoral profiles were observed in the CSF of neuroPASC compared with serum responses. All antibody isotypes (IgG, IgM, IgA) and subclasses (IgA1-2, IgG1-4) were detected in serum, whereas CSF was characterized by focused IgG1 (and absence of IgM). These data argue in favour of compartmentalized brain-specific responses against SARS-CoV-2 through selective transfer of antibodies from the serum to the CSF across the blood-brain barrier, rather than intrathecal synthesis, where more diversity in antibody classes/subclasses would be expected. Compared to individuals who did not develop post-acute complications following infection, individuals with neuroPASC had similar demographic features (median age 65 versus 66.5 years, respectively, P = 0.55; females 33% versus 44%, P = 0.52) but exhibited attenuated systemic antibody responses against SARS-CoV-2, characterized by decreased capacity to activate antibody-dependent complement deposition (ADCD), NK cell activation (ADNKA) and to bind Fcγ receptors. However, surprisingly, neuroPASC individuals showed significantly expanded antibody responses to other common coronaviruses, including 229E, HKU1, NL63 and OC43. This biased humoral activation across coronaviruses was particularly enriched in neuroPASC individuals with poor outcome, suggesting an 'original antigenic sin' (or immunologic imprinting), where pre-existing immune responses against related viruses shape the response to the current infection, as a key prognostic marker of neuroPASC disease. Overall, these findings point to a pathogenic role for compromised anti-SARS-CoV-2 responses in the CSF, likely resulting in incomplete virus clearance from the brain and persistent neuroinflammation, in the development of post-acute neurologic complications of SARS-CoV-2 infection.

Pathophysiology, diagnosis, and management of neuroinflammation in covid-19

Although neurological complications of SARS-CoV-2 infection are relatively rare, their potential long term morbidity and mortality have a significant impact, given the large numbers of infected patients. Covid-19 is now in the differential diagnosis of a number of common neurological syndromes including encephalopathy, encephalitis, acute demyelinating encephalomyelitis, stroke, and Guillain-Barré syndrome. Physicians should be aware of the pathophysiology underlying these presentations to diagnose and treat patients rapidly and appropriately. Although good evidence has been found for neurovirulence, the neuroinvasive and neurotropic potential of SARS-CoV-2 is limited. The pathophysiology of most complications is immune mediated and vascular, or both. A significant proportion of patients have developed long covid, which can include neuropsychiatric presentations. The mechanisms of long covid remain unclear. The longer term consequences of infection with covid-19 on the brain, particularly in terms of neurodegeneration, will only become apparent with time and long term follow-up.

Post-COVID-19 persistent olfactory, gustatory, and trigeminal chemosensory disorders: Definitions, mechanisms, and potential treatments

The nose and the oral cavities are the main sites for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into the body. Smell and taste deficits are the most common acute viral manifestations. Persistent smell disorders are the most common and bothersome complications after SARS-CoV-2 infection, lasting for months to years. The mechanisms and treatment of persistent post-coronavirus disease 2019 (COVID-19) smell and taste disorders are still challenges. Information sources for the review are PubMed, Centers for Disease Control and Prevention, Ovid Medline, Embase, Scopus, Web of Science, International Prospective Register of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature, Elton Bryson Stephens Company, Cochrane Effective Practice and Organization of Care, Cooperation in Science and Technology, International Clinical Trials Registry Platform, World Health Organization, Randomized Controlled Trial Number Registry, and MediFind. This review summarizes the up-to-date information about the prevalence, patterns at onset, and prognoses of post-COVID-19 smell and taste disorders, evidence for the neurotropism of SARS-CoV-2 and the overlap between SARS-CoV-1, Middle East respiratory syndrome coronavirus, and SARS-CoV-2 in structure, molecular biology, mode of replication, and host pathogenicity, the suggested cellular and molecular mechanisms for these post-COVID19 chemosensory disorders, and the applied pharmacotherapies and interventions as trials to treat these disorders, and the recommendations for future research to improve understanding of predictors and mechanisms of these disorders. These are crucial for hopeful proper treatment strategies.

Review of Neurological Manifestations of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can affect any part of the neuraxis. Many neurological conditions have been attributed to be caused by SARS-CoV-2, namely encephalopathy (acute necrotizing encephalopathy and encephalopathy with reversible splenial lesions), seizures, stroke, cranial nerve palsies, meningoencephalitis, acute disseminated encephalomyelitis (ADEM), transverse myelitis (long and short segment), Guillain-Barré syndrome (GBS) and its variants, polyneuritis cranialis, optic neuritis (ON), plexopathy, myasthenia gravis (MG), and myositis. The pathophysiology differs depending on the time frame of presentation. In patients with concomitant pulmonary disease, for instance, acute neurological illness appears to be caused by endotheliopathy and cytokine storm. Autoimmunity and molecular mimicry are causative for post-coronavirus disease 2019 (COVID-19)-sequelae. It has not yet been shown that the virus can penetrate the central nervous system (CNS) directly. This review aims to describe the disease and root pathogenic cause of the various neurological manifestations of COVID-19. We searched Pubmed/Medline and Google Scholar using the keywords "SARS-CoV-2" and "neurological illness" for articles published between January 2020 and November 2022. Then, we used the SWIFT-Review (Sciome LLC, North Carolina, United States), a text-mining workbench for systematic review, to classify the 1383 articles into MeSH hierarchical tree codes for articles on various parts of the nervous system, such as the CNS, peripheral nervous system, autonomic nervous system, neuromuscular junction, sensory system, and musculoskeletal system. Finally, we reviewed 152 articles in full text. SARS-CoV-2 RNA has been found in multiple brain areas without any histopathological changes. Despite the absence of in vivo virions or virus-infected cells, CNS inflammation has been reported, especially in the olfactory bulb and brain stem. SARS-CoV-2 genomes and proteins have been found in affected individuals' brain tissues, but corresponding neuropathologic changes are seldom found in these cases. Additionally, viral RNA can rarely be identified in neurological patients' CSF post hoc SARS-CoV-2 infection. Most patients with neurological symptoms do not have active viral replication in the nervous system and infrequently have typical clinical and laboratory characteristics of viral CNS infections. Endotheliopathy and the systemic inflammatory response to SARS-CoV-2 infection play a crucial role in developing neuro-COVID-19, with proinflammatory cytokine release mediating both pathological pathways. The systemic inflammatory mediators likely activate astrocytes and microglia across the blood-brain barrier, indirectly affecting CNS-specific immune activation and tissue injury. The management differs according to co-morbidities and the neurological disorder.

Neurological manifestations associated with SARS-CoV-2 infection: an updated review

SARS-CoV-2 is a single-stranded RNA virus that belongs to the group of seven coronaviruses that affect humans, and its infection causes the COVID-19 disease. The association between the COVID-19 condition and risk factors of neurological manifestations is unclear to date. This review aims to update the main neurological manifestations associated with SARS-CoV-2 disease. First, we present the hypothesis of the neuroinvasion mechanisms of SARS-CoV-2. Then, we discuss the possible symptoms related to patients with COVID-19 infection in the central and peripheral nervous systems, followed by the perspectives of diagnosis and treatment of possible neurological manifesta-tions. The hypothesis of the neuroinvasion mechanism includes direct routes, as the virus crosses the blood-brain barrier or the ACE2 receptor pathway role, and indirect pathways, such as malfunctions of the immune system and vascular system dysregulation. Various studies report COVID-19 consequences, such as neuroanatomic alterations and cognitive impairment, besides peripheral condi-tions, such as anosmia, ageusia, and Guillain Barré Syndrome. However, the het-erogeneity of the studies about neurologic damage in patients after COVID-19 infection precludes any generalization of current findings. Finally, new studies are necessary to understand the adequate diagnosis, therapeutic method of early treatment, and risk group of patients for neurological manifestations of COVID-19 post-infection.

Cerebrospinal fluid biomarkers in SARS-CoV-2 patients with acute neurological syndromes

BACKGROUND AND PURPOSE

Mechanisms underlying acute brain injury in SARS-CoV-2 patients remain poorly understood. A better characterization of such mechanisms remains essential to preventing long-term neurological sequelae. Our present aim was to study a panel of biomarkers of neuroinflammation and neurodegeneration in the cerebrospinal fluid (CSF) of NeuroCOVID patients.

METHODS

We retrospectively collected clinical and CSF biomarkers data from 24 NeuroCOVID adults seen at the University Hospital of Guadeloupe between March and June 2021.

RESULTS

Among 24 NeuroCOVID patients, 71% had encephalopathy and 29% meningoencephalitis. A number of these patients also experienced de novo movement disorder (33%) or stroke (21%). The CSF analysis revealed intrathecal immunoglobulin synthesis in 54% of NeuroCOVID patients (two with a type 2 pattern and 11 with a type 3) and elevated neopterin levels in 75% of them (median 9.1nM, IQR 5.6-22.1). CSF neurofilament light chain (NfL) was also increased compared to a control group of non-COVID-19 patients with psychiatric illnesses (2905ng/L, IQR 1428-7124 versus 1222ng/L, IQR 1049-1566). Total-tau was elevated in the CSF of 24% of patients, whereas protein 14-3-3, generally undetectable, reached intermediate levels in two patients. Finally, CSF Aß1-42 was reduced in 52.4% of patients (median 536ng/L, IQR 432-904) with no change in the Aß1-42/Aß1-40 ratio (0.082, IQR 0.060-0.096).

CONCLUSIONS

We showed an elevation of CSF biomarkers of neuroinflammation in NeuroCOVID patients and a rise of CSF NfL, evocative of neuronal damage. However, longitudinal studies are needed to determine whether NeuroCOVID could evolve into a chronic neurodegenerative condition.

Implementation of blood-brain barrier on microfluidic chip: recent advance and future prospects

The complex structure of the blood-brain barrier (BBB) hinders its modeling and the treatment of brain diseases. The microfluidic technology promotes the development of BBB-on-a-chip platforms, which can be used to reproduce the complex brain microenvironment and physiological reactions. Compared with traditional transwell technology, microfluidic BBB-on-a-chip shows great technical advantages in terms of flexible control of fluid shear stress in the chip and fabrication efficiency of the chip system, which can be enhanced by the development of lithography and three-dimensional (3D) printing. It is convenient to accurately monitor the dynamic changes of biochemical parameters of individual cells in the model by integrating an automatic super-resolution imaging sensing platform. In addition, biomaterials, especially hydrogels and conductive polymers, solve the limitations of microfluidic BBB-on-a-chip by compounding onto microfluidic chip to provide a 3D space and special performance on the microfluidic chip. The microfluidic BBB-on-a-chip promotes the development of basic research, including cell migration, mechanism exploration of neurodegenerative diseases, drug barrier permeability, SARS-CoV-2 pathology. This study summarizes the recent advances, challenges and future prospects of microfluidic BBB-on-a-chip, which can help to promote the development of personalized medicine and drug discovery.

Do SARS-CoV-2 Variants Differ in Their Neuropathogenicity?

Neurological complications associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections are a huge societal problem. Although the neuropathogenicity of SARS-CoV-2 is not yet fully understood, there is evidence that SARS-CoV-2 can invade and infect cells of the central nervous system. Kong et al. (https://doi.org/10.1128/mbio.02308-22) shows that the mechanism of virus entry into astrocytes in brain organoids and primary astrocytes differs from entry into respiratory epithelial cells. However, how SARS-CoV-2 enters susceptible CNS cells and whether there are differences among SARS-CoV-2 variants is still unclear. In vivo and in vitro models are useful to study these important questions and may reveal important differences among SARS-CoV-2 variants in their neuroinvasive, neurotropic, and neurovirulent potential. In this commentary we address how this study contributes to the understanding of the neuropathology of SARS-CoV-2 and its variants.

SARS-CoV-2 and Hypertension: Evidence Supporting Invasion into the Brain Via Baroreflex Circuitry and the Role of Imbalanced Renin-Angiotensin-Aldosterone-System

Hypertension is considered one of the most critical risk factors for COVID-19. Evidence suggests that SARS-CoV-2 infection produces intense effects on the cardiovascular system by weakening the wall of large vessels via vasa-vasorum. In this commentary, we propose that SARS-CoV-2 invades carotid and aortic baroreceptors, leading to infection of the nucleus tractus solitari (NTS) and paraventricular hypothalamic nucleus (PVN), and such dysregulation of NTS and PVN following infection causes blood pressure alteration at the central level. We additionally explored the hypothesis that SARS-CoV-2 favors the internalization of membrane ACE2 receptors generating an imbalance of the renin-angiotensin-aldosterone system (RAAS), increasing the activity of angiotensin II (ANG-II), disintegrin, and metalloproteinase 17 domain (ADAM17/TACE), eventually modulating the integration of afferents reaching the NTS from baroreceptors and promoting increased blood pressure. These mechanisms are related to the increased sympathetic activity, which leads to transient or permanent hypertension associated with SARS-CoV-2 invasion, contributing to the high number of deaths by cardiovascular implications.

Finding positive SARS-CoV-2 RT-PCR in cerebrospinal fluid of two pediatric patients with severe COVID-19: a brief case report

BACKGROUND

There is growing evidence of nervous system involvement and related complaints in children with coronavirus disease 2019 (COVID-19). However, it seems that attempts to track of the virus in the nervous system have so far been unsuccessful.

CASE PRESENTATION

Here we describe two pediatric cases of severe COVID-19 who had positive cerebrospinal fluid (CSF) and nasopharyngeal polymerase chain reaction (PCR) tests for severe acute respiratory syndrome coronavirus disease 2019 (SARS-CoV-2). A 36-month-old girl who presented with fever, diarrhea, mild left ventricular dysfunction and bizarre movements, and a five-month-old boy who presented with fever, watery diarrhea, severe dehydration, mottling, and two episodes of seizure. Their CSF analyses and cultures were normal. They admitted in intensive care unit (ICU) for near four days and discharged after ten days without any complaint.

CONCLUSION

This is one of the first reports of the presence of coronavirus in the central nervous system in COVID-19 pediatric patients, emphasizing the neurotropism and neuroinvasion characteristics of the virus.

Consensus Clinical Guidance for Diagnosis and Management of Adult COVID-19 Encephalopathy Patients

Encephalopathy, a common condition among patients hospitalized with COVID-19, can be a challenge to manage and negatively affect prognosis. While encephalopathy may present clinically as delirium, subsyndromal delirium, or coma and may be a result of systemic causes such as hypoxia, COVID-19 has also been associated with more prolonged encephalopathy due to less common but nevertheless severe complications, such as inflammation of the brain parenchyma (with or without cerebrovascular involvement), demyelination, or seizures, which may be disproportionate to COVID-19 severity and require specific management. Given the large number of patients hospitalized with severe acute respiratory syndrome coronavirus-2 infection, even these relatively unlikely complications are increasingly recognized and are particularly important because they require specific management. Therefore, the aim of this review is to provide pragmatic guidance on the management of COVID-19 encephalopathy through consensus agreement of the Global COVID-19 Neuro Research Coalition. A systematic literature search of MEDLINE, medRxiv, and bioRxiv was conducted between January 1, 2020, and June 21, 2021, with additional review of references cited within the identified bibliographies. A modified Delphi approach was then undertaken to develop recommendations, along with a parallel approach to score the strength of both the recommendations and the supporting evidence. This review presents analysis of contemporaneous evidence for the definition, epidemiology, and pathophysiology of COVID-19 encephalopathy and practical guidance for clinical assessment, investigation, and both acute and long-term management.

Brain stem encephalitis is a rare complication of COVID-19

Here, we describe the clinical phenotype of SARS-CoV-2-related CNS disease and evaluate the SARS-CoV-2 antibody index as a tool to differentiate between a direct (viral) and indirect etiology. Out of >4000 hospitalized patients with COVID-19, we included 13 patients with neurological symptoms with suspicion of neuroinflammation. On clinical grounds, eight were classified as having a possible/probable relationship between neurological symptoms and COVID-19. A clinically distinctive phenotype of brainstem and cerebellar symptoms was seen in 6/8 patients. As we found a positive SARS-CoV-2 antibody index in 3/5 patients, indicating specific intrathecal SARS-CoV-2 IgG production, a direct link with SARS-CoV-2 is likely.

Clinical usefulness of testing for severe acute respiratory syndrome coronavirus 2 antibodies

In the COVID-19 pandemic era, antibody testing against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has proven an invaluable tool and herein we highlight some of the most useful clinical and/or epidemiological applications of humoral immune responses recording. Anti-spike circulating IgGs and SARS-CoV-2 neutralizing antibodies can serve as predictors of disease progression or disease prevention, whereas anti-nucleocapsid antibodies can help distinguishing infection from vaccination. Also, in the era of immunotherapies we address the validity of anti-SARS-CoV-2 antibody monitoring post-infection and/or vaccination following therapies with the popular anti-CD20 monoclonals, as well as in the context of various cancers or autoimmune conditions such as rheumatoid arthritis and multiple sclerosis. Additional crucial applications include population immunosurveillance, either at the general population or at specific communities such as health workers. Finally, we discuss how testing of antibodies in cerebrospinal fluid can inform us on the neurological complications that often accompany COVID-19.

Hydrocephalus As Possible Prodromal Manifestation of COVID-19: A Report of Two Cases

Although the etiopathology of normal pressure hydrocephalus (NPH) is still not completely defined, several studies in recent years have highlighted the role of neuro-inflammation mediators in its development. During COVID-19, the infected host develops a multifaceted inflammatory syndrome, that may lead to an uncontrolled immune system response also localized in the host nervous system. In fact, the target of the viral Spike protein, the angiotensin-converting enzyme 2 (ACE2) receptors, is widely expressed in different areas of CNS such as the olfactory epithelium, and the choroid plexus. As for idiopathic NPH, the massive release of inflammatory mediators may result in altered CSF dynamics and consequent sudden clinical decompensation. We report the cases of two patients with a known iNPH condition, in which neurological symptoms suddenly worsened, requiring hospitalization, without any evident precipitating cause. Both patients tested positive for the COVID-19 virus shortly after the neurological impairment, which had occurred, therefore, during the incubation period of the infection. On the basis of our experience we advise, in cases of NPH patients with sudden neurological worsening, to perform a molecular COVID-19 swab at the moment of clinical impairment. We, therefore, recommend considering SARS-CoV-2 infection in the differential diagnosis of a sudden and otherwise unexplainable impairment of hydrocephalic patients. Furthermore, we believe clinicians should invite NPH patients to adopt adequate preventive measures to protect them from SARS-CoV-2 infection.

Non-neutralizing antibodies to SARS-Cov-2-related linear epitopes induce psychotic-like behavior in mice

Objective

An increasing number of studies have reported that numerous patients with coronavirus disease 2019 (COVID-19) and vaccinated individuals have developed central nervous system (CNS) symptoms, and that most of the antibodies in their sera have no virus-neutralizing ability. We tested the hypothesis that non-neutralizing anti-S1-111 IgG induced by the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could negatively affect the CNS.

Methods

After 14-day acclimation, the grouped ApoE-/- mice were immunized four times (day 0, day 7, day 14, day 28) with different spike-protein-derived peptides (coupled with KLH) or KLH via subcutaneous injection. Antibody level, state of glial cells, gene expression, prepulse inhibition, locomotor activity, and spatial working memory were assessed from day 21.

Results

An increased level of anti-S1-111 IgG was measured in their sera and brain homogenate after the immunization. Crucially, anti-S1-111 IgG increased the density of microglia, activated microglia, and astrocytes in the hippocampus, and we observed a psychomotor-like behavioral phenotype with defective sensorimotor gating and impaired spontaneity among S1-111-immunized mice. Transcriptome profiling showed that up-regulated genes in S1-111-immunized mice were mainly associated with synaptic plasticity and mental disorders.

Discussion

Our results show that the non-neutralizing antibody anti-S1-111 IgG induced by the spike protein caused a series of psychotic-like changes in model mice by activating glial cells and modulating synaptic plasticity. Preventing the production of anti-S1-111 IgG (or other non-neutralizing antibodies) may be a potential strategy to reduce CNS manifestations in COVID-19 patients and vaccinated individuals.

COVID-19 induces CNS cytokine expression and loss of hippocampal neurogenesis

Infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with acute and postacute cognitive and neuropsychiatric symptoms including impaired memory, concentration, attention, sleep and affect. Mechanisms underlying these brain symptoms remain understudied. Here we report that SARS-CoV-2-infected hamsters exhibit a lack of viral neuroinvasion despite aberrant blood-brain barrier permeability. Hamsters and patients deceased from coronavirus disease 2019 (COVID-19) also exhibit microglial activation and expression of interleukin (IL)-1β and IL-6, especially within the hippocampus and the medulla oblongata, when compared with non-COVID control hamsters and humans who died from other infections, cardiovascular disease, uraemia or trauma. In the hippocampal dentate gyrus of both COVID-19 hamsters and humans, we observed fewer neuroblasts and immature neurons. Protracted inflammation, blood-brain barrier disruption and microglia activation may result in altered neurotransmission, neurogenesis and neuronal damage, explaining neuropsychiatric presentations of COVID-19. The involvement of the hippocampus may explain learning, memory and executive dysfunctions in COVID-19 patients.

The neurobiology of long COVID

Persistent neurological and neuropsychiatric symptoms affect a substantial fraction of people after COVID-19 and represent a major component of the post-acute COVID-19 syndrome, also known as long COVID. Here, we review what is understood about the pathobiology of post-acute COVID-19 impact on the CNS and discuss possible neurobiological underpinnings of the cognitive symptoms affecting COVID-19 survivors. We propose the chief mechanisms that may contribute to this emerging neurological health crisis.

Neuro-Immune Interactions in Severe COVID-19 Infection

SARS-CoV-2 is a new coronavirus that has affected the world since 2019. Interstitial pneumonia is the most common clinical presentation, but additional symptoms have been reported, including neurological manifestations. Severe forms of infection, especially in elderly patients, present as an excessive inflammatory response called "cytokine storm", which can lead to acute respiratory distress syndrome (ARDS), multiorgan failure and death. Little is known about the relationship between symptoms and clinical outcomes or the characteristics of virus-host interactions. The aim of this narrative review is to highlight possible links between neurological involvement and respiratory damage mediated by pathological inflammatory pathways in SARS-CoV-2 infection. We will focus on neuro-immune interactions and age-related immunity decline and discuss some pathological mechanisms that contribute to negative outcomes in COVID-19 patients. Furthermore, we will describe available therapeutic strategies and their effects on COVID-19 neurological symptoms.

Autoimmunity and SARS-CoV-2 infection: Unraveling the link in neurological disorders

According to the World Health Organization, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has already infected more than 400 million people and caused over 5 million deaths globally. The infection is associated with a wide spectrum of clinical manifestations, ranging from no signs of illness to severe pathological complications that go beyond the typical respiratory symptoms. On this note, new-onset neurological and neuropsychiatric syndromes have been increasingly reported in a large fraction of COVID-19 patients, thus potentially representing a significant public health threat. Although the underlying pathophysiological mechanisms remain elusive, a growing body of evidence suggests that SARS-CoV-2 infection may trigger an autoimmune response, which could potentially contribute to the establishment and/or exacerbation of neurological disorders in COVID-19 patients. Shedding light on this aspect is urgently needed for the development of effective therapeutic intervention. This review highlights the current knowledge of the immune responses occurring in Neuro-COVID patients and discusses potential immune-mediated mechanisms by which SARS-CoV-2 infection may trigger neurological complications.

COVID-19 Infection Presenting With Severe Hydrocephalus and Acute Stroke: A Case Report

Hydrocephalus is the accumulation of cerebrospinal fluid (CSF) in the cerebral ventricles and is considered an emergency in acute presentation. Hydrocephalus typically presents with symptoms of headache, nausea, vomiting, lethargy, vision changes and seizure; furthermore, narrowing down the underlying etiology of hydrocephalus can aid in treatment and management options. We present a rare case of a patient that presented with a recent diagnosis of COVID-19 and was found to have acute hydrocephalus and stroke. The aim of this case report is to explore the link between COVID-19 and the development of hydrocephalus and stroke by delineating the underlying pathophysiology of COVID-19 as well as the etiologies of hydrocephalus and possible management strategies. We hope to highlight the importance of keeping an open differential for presentations of headaches and also emphasize the potential complications of COVID-19 infection to help better patient outcomes.

SARS-CoV-2 infection and diabetes: Pathophysiological mechanism of multi-system organ failure

Since the discovery of the coronavirus disease 2019 outbreak, a vast majority of studies have been carried out that confirmed the worst outcome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in people with preexisting health conditions, including diabetes, obesity, hypertension, cancer, and cardiovascular diseases. Likewise, diabetes itself is one of the leading causes of global public health concerns that impose a heavy global burden on public health as well as socio-economic development. Both diabetes and SARS-CoV-2 infection have their independent ability to induce the pathogenesis and severity of multi-system organ failure, while the co-existence of these two culprits can accelerate the rate of disease progression and magnify the severity of the disease. However, the exact pathophysiology of multi-system organ failure in diabetic patients after SARS-CoV-2 infection is still obscure. This review summarized the organ-specific possible molecular mechanisms of SARS-CoV-2 and diabetes-induced pathophysiology of several diseases of multiple organs, including the lungs, heart, kidneys, brain, eyes, gastrointestinal system, and bones, and sub-sequent manifestation of multi-system organ failure.

Neurological Complications of COVID-19 in the Elderly

SARS-CoV-2 virus is a β-coronavirus and produces a severe viral pneumonia which can be complicated by acute respiratory distress syndrome and multiorgan failure. As knowledge of the new coronavirus infection (COVID-19) increases, it has become known that SARS-CoV-2 has pronounced neurotropism, producing a wide spectrum of neurological complications. This article addresses the characteristics of the neurological complications of COVID-19 in elderly people.

SARS-CoV-2 invades cognitive centers of the brain and induces Alzheimer's-like neuropathology

The neurotropism of SARS-CoV-2 and the phenotypes of infected neurons are still in debate. Long COVID manifests with "brain diseases" and the cause of these brain dysfunction is mysterious. Here, we analyze 34 age- and underlying disease-matched COVID-19 or non-COVID-19 human brains. SARS-CoV-2 RNA, nucleocapsid, and spike proteins are present in neurons of the cognitive centers of all COVID-19 patients, with its non-structural protein NSF2 detected in adult cases but not in the infant case, indicating viral replications in mature neurons. In adult COVID-19 patients without underlying neurodegeneration, SARS-CoV-2 infection triggers Aβ and p-tau deposition, degenerating neurons, microglia activation, and increased cytokine, in some cases with Aβ plaques and p-tau pretangles. The number of SARS-CoV-2 + cells is higher in patients with neurodegenerative diseases than in those without such conditions. SARS-CoV-2 further activates microglia and induces Aβ and p-tau deposits in non-Alzheimer's neurodegenerative disease patients. SARS-CoV-2 infects mature neurons derived from inducible pluripotent stem cells from healthy and Alzheimer's disease (AD) individuals through its receptor ACE2 and facilitator neuropilin-1. SARS-CoV-2 triggers AD-like gene programs in healthy neurons and exacerbates AD neuropathology. An AD infectious etiology gene signature is identified through SARS-CoV-2 infection and silencing the top three downregulated genes in human primary neurons recapitulates the neurodegenerative phenotypes of SARS-CoV-2. Thus, our data suggest that SARS-CoV-2 invades the brain and activates an AD-like program.

SARS-CoV-2 infection in multiple sclerosis patients: interaction with treatments, adjuvant therapies, and vaccines against COVID-19

The SARS-CoV-2 pandemic has raised particular concern for people with Multiple Sclerosis, as these people are believed to be at increased risk of infection, especially those being treated with disease-modifying therapies. Therefore, the objective of this review was to describe how COVID-19 affects people who suffer from Multiple Sclerosis, evaluating the risk they have of suffering an infection by this virus, according to the therapy to which they are subjected as well as the immune response of these patients both to infection and vaccines and the neurological consequences that the virus can have in the long term. The results regarding the increased risk of infection due to treatment are contradictory. B-cell depletion therapies may cause patients to have a lower probability of generating a detectable neutralizing antibody titer. However, more studies are needed to help understand how this virus works, paying special attention to long COVID and the neurological symptoms that it causes.

Blood-brain Barrier Damage is Pivotal for SARS-CoV-2 Infection to the Central Nervous System

Transsynaptic transport is the most accepted proposal to explain the SARS-CoV-2 infection of the CNS. Nevertheless, emerging evidence shows that neurons do not express the SARS-CoV-2 receptor ACE2, which highlights the importance of the blood-brain barrier (BBB) in preventing virus entry to the brain. In this study, we examine the presence of SARS-CoV-2 messenger ribonucleic acid (mRNA) and the cytokine profile in cerebrospinal fluids (CSF) from two patients with a brain tumor and COVID-19. To determine the BBB damage, we evaluate the Q- albumin index, which is an indirect parameter to assess the permeability of this structure. The Q-albumin index of the patient with an intraventricular brain tumor suggests that the BBB is undamaged, preventing the passage of SARS-CoV-2 and pro-inflammatory molecules. The development of brain tumors that disrupt the BBB (measured by the Q-albumin index), in this case, a petroclival meningioma (Case 1), allows the free passage of the SARS-CoV-2 virus and probably lets the free transit of pro-inflammatory molecules to the CNS, which leads to a possible activation of the microglia (astrogliosis) and an exacerbated immune response represented by IL-13, IFN-γ, and IL-2 trying to inhibit both the infection and the carcinogenic process.

Encephalomyelitis associated with coronavirus disease 2019: a case report

Background

Despite a considerable number of articles regarding neurological manifestations associated with severe acute respiratory syndrome coronavirus 2 infection, reports on transverse myelitis and encephalitis are scarce.

Case presentation

We report a 35-year-old Asian Arab female presenting with longitudinally extensive transverse myelitis within 3 weeks after being diagnosed with mild coronavirus disease 2019 infection. Administration of high-dose methylprednisolone led to significant clinical improvement. However, 2 days after discharge, the patient was readmitted with encephalitis manifestations, consisting of fever and loss of consciousness, along with deterioration in myelitis symptoms. Severe acute respiratory syndrome coronavirus 2 antibody was detected in cerebrospinal fluid, but DNA of severe acute respiratory syndrome coronavirus 2 was not found. Clinical recovery was achieved after the administration of intravenous immunoglobulin.

Conclusion

Longitudinally extensive transverse myelitis can be a neurological manifestation of coronavirus disease 2019 and can be followed by encephalomyelitis episodes. High-dose steroids and intravenous immunoglobulin as an immunomodulator are possible effective treatment options.

Cerebral microvascular complications associated with SARS-CoV-2 infection: How did it occur and how should it be treated?

Cerebral microvascular disease has been reported as a central feature of the neurological disorders in patients with SARS-CoV-2 infection that may be associated with an increased risk of ischemic stroke. The main pathomechanism in the development of cerebrovascular injury due to SARS-CoV-2 infection can be a consequence of endothelial cell dysfunction as a structural part of the blood-brain barrier (BBB), which may be accompanied by increased inflammatory response and thrombocytopenia along with blood coagulation disorders. In this review, we described the properties of the BBB, the neurotropism behavior of SARS-CoV-2, and the possible mechanisms of damage to the CNS microvascular upon SARS-CoV-2 infection.

Cerebral dysfunctions caused by sepsis during ageing

Systemic inflammation elicited by sepsis can induce an acute cerebral dysfunction known as sepsis-associated encephalopathy (SAE). Recent evidence suggests that SAE is common but shows a dynamic trajectory over time. Half of all patients with sepsis develop SAE in the intensive care unit, and some survivors present with sustained cognitive impairments for several years after initial sepsis onset. It is not clear why some, but not all, patients develop SAE and also the factors that determine the persistence of SAE. Here, we first summarize the chronic pathology and the dynamic changes in cognitive functions seen after the onset of sepsis. We then outline the cerebral effects of sepsis, such as neuroinflammation, alterations in neuronal synapses and neurovascular changes. We discuss the key factors that might contribute to the development and persistence of SAE in older patients, including premorbid neurodegenerative pathology, side effects of sedatives, renal dysfunction and latent virus reactivation. Finally, we postulate that some of the mechanisms that underpin neuropathology in SAE may also be relevant to delirium and persisting cognitive impairments that are seen in patients with severe COVID-19.

Hypertonic Solution in Severe COVID-19 Patient: A Potential Adjuvant Therapy

Coronavirus disease 2019 (COVID-19) features hyper-inflammation, cytokine storm, neutrophil function changes, and sodium chloride (NaCl) homeostasis disruption, while the treatment with NaCl hypertonic solutions (HS) controls electrolytic body homeostasis and cell functions. HS treatment is a simple, popular, economic, and feasible therapy to regulate leukocyte function with a robust anti-inflammatory effect in many inflammatory diseases. The purpose of this narrative review is to highlight the knowledge on the use of HS approaches against viral infection over the past years and to describe the mechanisms involved in the release of neutrophil extracellular traps (NETs) and production of cytokine in severe lung diseases, such as COVID-19. We reported the consequences of hyponatremia in COVID-19 patients, and the immunomodulatory effects of HS, either in vitro or in vivo. We also described the relationship between electrolyte disturbances and COVID-19 infection. Although there is still a lack of clinical trials, hypertonic NaCl solutions have marked effects on neutrophil function and NETs formation, emerging as a promising adjuvant therapy in COVID-19.

What SARS-CoV-2 does to our brains

Neurological symptoms in SARS-CoV-2-infected patients have been reported, but their cause remains unclear. In theory, the neurological symptoms observed after SARS-CoV-2 infection could be (1) directly caused by the virus infecting brain cells, (2) indirectly by our body’s local or systemic immune response toward the virus, (3) by coincidental phenomena, or (4) a combination of these factors. As indisputable evidence of intact and replicating SARS-CoV-2 particles in the central nervous system (CNS) is currently lacking, we suggest focusing on the host’s immune reaction when trying to understand the neurocognitive symptoms associated with SARS-CoV-2 infection. In this perspective, we discuss the possible immune-mediated mechanisms causing functional or structural CNS alterations during acute infection as well as in the post-infectious context. We also review the available literature on CNS affection in the context of COVID-19 infection, as well as observations from animal studies on the molecular pathways involved in sickness behavior.

Neuroimmune disorders in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the aetiologic agent of the coronavirus disease 2019 (COVID-19), is now rapidly disseminating throughout the world with 147,443,848 cases reported so far. Around 30-80% of cases (depending on COVID-19 severity) are reported to have neurological manifestations including anosmia, stroke, and encephalopathy. In addition, some patients have recognised autoimmune neurological disorders, including both central (limbic and brainstem encephalitis, acute disseminated encephalomyelitis [ADEM], and myelitis) and peripheral diseases (Guillain-Barré and Miller Fisher syndrome). We systematically describe data from 133 reported series on the Neurology and Neuropsychiatry of COVID-19 blog ( https://blogs.bmj.com/jnnp/2020/05/01/the-neurology-and-neuropsychiatry-of-covid-19/ ) providing a comprehensive overview concerning the diagnosis, and treatment of patients with neurological immune-mediated complications of SARS-CoV-2. In most cases the latency to neurological disorder was highly variable and the immunological or other mechanisms involved were unclear. Despite specific neuronal or ganglioside antibodies only being identified in 10, many had apparent responses to immunotherapies. Although the proportion of patients experiencing immune-mediated neurological disorders is small, the total number is likely to be underestimated. The early recognition and improvement seen with use of immunomodulatory treatment, even in those without identified autoantibodies, makes delayed or missed diagnoses risk the potential for long-term disability, including the emerging challenge of post-acute COVID-19 sequelae (PACS). Finally, potential issues regarding the use of immunotherapies in patients with pre-existent neuro-immunological disorders are also discussed.

Is there a difference between GBS triggered by COVID-19 and those of other origins?

Background

Since the outbreak of the coronavirus disease 2019 (COVID-19), an increasing number of Guillain–Barré syndrome (GBS) cases following the infection has been reported. The aim of our study was to detect patients with GBS treated in our hospital over a 1-year period and to compare the characteristics and outcomes of those triggered by COVID-19 with the rest of GBS patients. Our prospective study included 29 patients who were diagnosed with GBS from March 2020 to March 2021. Based on the preceding event, patients were stratified as post-COVID-19 and non-COVID-19. The GBS disability scale (GDS) was used to assess functional disability.

Results

We identified 10 (34.5%) patients with post-COVID-19 GBS and 19 (65.5%) patients with non-COVID-19 GBS. The median time from the preceding event to the symptoms onset was longer in post-COVID-19 than in non-COVID-19 GBS patients (p = 0.04). However, the time from the symptom onset to the nadir did not differ (p = 0.12). GDS at admission, as well as at nadir, did not differ between these two groups. The level of proteinorrachia was higher in post-COVID-19 GBS patients (p = 0.035). The most frequent subtype of GBS in both groups was acute inflammatory demyelinating polyneuropathy (AIDP). GDS score at discharge (p = 0.56) did not differ between two study groups.

Conclusions

There was no difference in clinical and electrophysiological features, disease course, and outcome in post-COVID-19 compared with non-COVID-19 GBS patients.

SARS-CoV-2 and Multiple Sclerosis: Potential for Disease Exacerbation

While the respiratory tract is the primary route of entry for SARS-CoV-2, evidence shows that the virus also impacts the central nervous system. Intriguingly, case reports have documented SARS-CoV-2 patients presenting with demyelinating lesions in the brain, spinal cord, and optic nerve, suggesting possible implications in neuroimmune disorders such as multiple sclerosis (MS) and other related neuroimmune disorders. However, the cellular mechanisms underpinning these observations remain poorly defined. The goal of this paper was to review the literature to date regarding possible links between SARS-CoV-2 infection and neuroimmune demyelinating diseases such as MS and its related disorders, with the aim of positing a hypothesis for disease exacerbation. The literature suggests that SARS-CoV, SARS-CoV-2, and orthologous murine coronaviruses invade the CNS via the olfactory bulb, spreading to connected structures via retrograde transport. We hypothesize that a glial inflammatory response may contribute to damaged oligodendrocytes and blood brain barrier (BBB) breakdown, allowing a second route for CNS invasion and lymphocyte infiltration. Potential for molecular mimicry and the stimulation of autoreactive T cells against myelin is also described. It is imperative that further studies on SARS-CoV-2 neuroinvasion address the adverse effects of the virus on myelin and exacerbation of MS symptoms, as nearly 3 million people suffer from MS worldwide.

Does SARS-CoV-2 affect neurodegenerative disorders? TLR2, a potential receptor for SARS-CoV-2 in the CNS

The coronavirus (COVID-19) pandemic, caused by severe acute respiratory system coronavirus 2 (SARS-CoV-2), has created significant challenges for scientists seeking to understand the pathogenic mechanisms of SARS-CoV-2 infection and to identify the best therapies for infected patients. Although ACE2 is a known receptor for the virus and has been shown to mediate viral entry into the lungs, accumulating reports highlight the presence of neurological symptoms resulting from infection. As ACE2 expression is low in the central nervous system (CNS), these neurological symptoms are unlikely to be caused by ACE2-virus binding. In this review, we will discuss a proposed interaction between SARS-CoV-2 and Toll-like receptor 2 (TLR2) in the CNS. TLR2 is an innate immune receptor that recognizes exogenous microbial components but has also been shown to interact with multiple viral components, including the envelope (E) protein of SARS-CoV-2. In addition, TLR2 plays an important role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Based on these observations, we hypothesize that TLR2 may play a critical role in the response to SARS-CoV-2 infiltration in the CNS, thereby resulting in the induction or acceleration of AD and PD pathologies in patients.

The Impact of the COVID-19 Virus Pandemic on the Incidence of First Psychotic Spectrum Disorders

The effects of COVID-19 on the human body are not yet understood enough. Medical history provides information on cases of psychiatric symptoms during viral infections in the 20th century, such as the influenza pandemic. Currently, it is observed that there is an increasing number of new psychiatric disorders in previously healthy individuals. In addition, because of the decreased amount of reporting to health care providers, including psychiatrists, many physicians suggest that the number of neuropsychiatric disorders may be underestimated. In this paper, we review available studies on the occurrence of first-time psychotic spectrum disorder (PSD) in individuals related to SARS-CoV-2 infection. The reviewed studies suggest that first-time psychotic disorder in COVID-19 patients is statistically significantly more frequent compared to influenza, as well as to other respiratory infections. The emergence of new PSDs is explained by direct neurotropism of the virus on the one hand and by immunological mechanisms on the other. The main conclusions of this review should be treated with caution, and future research on this topic is needed. The authors recognize the particular need to develop standardized laboratory panels that include inflammatory markers (IL-6, TNF-α), cerebrospinal fluid (CSF) testing, and SARS-CoV-2 antibody assays to entirely understand the etiology of neuropsychiatric complications of SARS-CoV-2 infections and the pandemic itself. In addition, public health efforts are required to promote mental health, especially during COVID-19.

Normal pressure hydrocephalus associated with COVID-19 infection: a case report

BACKGROUND

COVID-19 is a pandemic disease responsible for many deaths worldwide. Many neurological manifestations have been described. We report a case of normal pressure hydrocephalus (NPH) 2 months after acute COVID19 infection, in a patient without other risk factors.

CASE PRESENTATION

A 45-year-old male patient presented an 8-month history of progressive gait disorder and cognitive impairment after being hospitalized for SARS-CoV-2 infection. Magnetic resonance imaging (MRI) was compatible with NPH. A spinal tap test was positive and there was progressive improvement after shunting, with complete resolution of symptoms.

CONCLUSION

Other infections such as syphilis, cryptococcosis and Lyme disease have been associated with NPH. Possible mechanisms for NPH after COVID include disruption of choroid plexus cells by direct viral invasion or as a result of neuroinflammation and cytokine release and hypercoagulability leading to venous congestion and abnormalities of CSF flow. Given the significance of NPH as a cause of reversible dementia, it is important to consider the possibility of a causal association with COVID19 and understand the mechanisms behind this association.

Emerging Knowledge of the Neurobiology of COVID-19

Many patients with COVID-19 will experience acute or longer-term neuropsychiatric complications. The neurobiological mechanisms behind these are beginning to emerge; however, the neurotropic hypothesis is not strongly supported by clinical data. The inflammatory response to SARS-CoV-2 is likely to be responsible for delirium and other common acute neuropsychiatric manifestations. Vascular abnormalities such as endotheliopathies contribute to stroke and cerebral microbleeds, with their attendant neuropsychiatric sequelae. Longer-term neuropsychiatric syndromes fall into 2 broad categories: neuropsychiatric deficits occurring after severe (hospitalized) COVID-19 and "long COVID," which occurs in many patients with a milder acute COVID-19 illness.

Lethal Pediatric Cerebral Vasculitis Triggered by Severe Acute Respiratory Syndrome Coronavirus 2

BACKGROUND

We report the clinical, radiological, laboratory, and neuropathological findings in support of the first diagnosis of lethal, small-vessel cerebral vasculitis triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a pediatric patient.

PATIENT DESCRIPTION

A previously healthy, eight-year-old Hispanic girl presented with subacute left-sided weakness two weeks after a mild febrile illness. SARS-CoV-2 nasopharyngeal swab was positive. Magnetic resonance imaging revealed an enhancing right frontal lobe lesion with significant vasogenic edema. Two brain biopsies of the lesion showed perivascular and intraluminal lymphohistiocytic inflammatory infiltrate consistent with vasculitis. Despite extensive treatment with immunomodulatory therapies targeting primary angiitis of the central nervous system, she experienced neurological decline and died 93 days after presentation. SARS-CoV-2 testing revealed positive serum IgG and positive cerebrospinal fluid IgM. Comprehensive infectious, rheumatologic, hematologic/oncologic, and genetic evaluation did not identify an alternative etiology. Postmortem brain autopsy remained consistent with vasculitis.

CONCLUSION

This is the first pediatric presentation to suggest that SARS-CoV-2 can lead to a fatal, postinfectious, inflammatory small-vessel cerebral vasculitis. Our patient uniquely included supportive cerebrospinal fluid and postmortem tissue analysis. While most children recover from the neurological complications of SARS-CoV-2, we emphasize the potential mortality in a child with no risk factors for severe disease.

A Peek into Pandora’s Box: COVID-19 and Neurodegeneration

Ever since it was first reported in Wuhan, China, the coronavirus-induced disease of 2019 (COVID-19) has become an enigma of sorts with ever expanding reports of direct and indirect effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on almost all the vital organ systems. Along with inciting acute pulmonary complications, the virus attacks the cardiac, renal, hepatic, and gastrointestinal systems as well as the central nervous system (CNS). The person-to-person variability in susceptibility of individuals to disease severity still remains a puzzle, although the comorbidities and the age/gender of a person are believed to play a key role. SARS-CoV-2 needs angiotensin-converting enzyme 2 (ACE2) receptor for its infectivity, and the association between SARS-CoV-2 and ACE2 leads to a decline in ACE2 activity and its neuroprotective effects. Acute respiratory distress may also induce hypoxia, leading to increased oxidative stress and neurodegeneration. Infection of the neurons along with peripheral leukocytes’ activation results in proinflammatory cytokine release, rendering the brain more susceptible to neurodegenerative changes. Due to the advancement in molecular biology techniques and vaccine development programs, the world now has hope to relatively quickly study and combat the deadly virus. On the other side, however, the virus seems to be still evolving with new variants being discovered periodically. In keeping up with the pace of this virus, there has been an avalanche of studies. This review provides an update on the recent progress in adjudicating the CNS-related mechanisms of SARS-CoV-2 infection and its potential to incite or accelerate neurodegeneration in surviving patients. Current as well as emerging therapeutic opportunities and biomarker development are highlighted.