Acute and persistent infection of human neural cell lines by human coronavirus OC43

Indomethacin inhibits human seasonal coronaviruses at late stages of viral replication in lung cells: Impact on virus-induced COX-2 expression

Coronaviruses (CoV), zoonotic viruses periodically emerging worldwide, represent a constant potential threat to humans. To date, seven human coronaviruses (HCoV) have been identified: HCoV-229E, HCoV-NL63, HCoV-OC43 and HCoV-HKU1, globally circulating in the human population (seasonal coronaviruses, sHCoV), and three highly-pathogenic coronaviruses, SARS-CoV, MERS-CoV and SARS-CoV-2. Although sHCoV generally cause only mild respiratory diseases, severe complications may occur in specific populations, highlighting the need for broad-spectrum anti-coronavirus drugs. Herein we show that indomethacin (INDO), a non-steroidal anti-inflammatory drug widely used in the clinic for its potent anti-inflammatory and analgesic properties, effectively inhibits the replication of Alpha-coronavirus HCoV-229E and Beta-coronavirus HCoV-OC43 in human lung-derived cells. Indomethacin does not interfere with HCoV binding or entry into target cells, but acts at late stages of the virus life cycle, inhibiting viral RNA synthesis and infectious viral particles production. Although INDO anti-inflammatory action is mediated by blocking cyclooxygenase-1 and -2 (COX-1/2) enzymatic activity, the antiviral effect appears to be cyclooxygenase-independent and is not mimicked by the potent COX-1/2 inhibitor aspirin. Interestingly we found that both seasonal HCoVs markedly (>100 fold) induce the expression of the pro-inflammatory mediator COX-2 in lung cells; notably, INDO-treatment was found to effectively inhibit virus-induced COX-2 expression at the transcriptional level, revealing an additional mechanism to prevent COX-2-mediated inflammatory reactions in HCoV-infected lung cells, besides COX activity inhibition. Altogether the results indicate that indomethacin, possessing both potent anti-inflammatory properties and a direct antiviral activity against HCoV, could be effective in the treatment of Alpha- and Beta-coronavirus infections.

Human coronavirus OC43 infection remodels connexin 43-mediated gap junction intercellular communication in vitro

β-coronaviruses cause acute infection in the upper respiratory tract, resulting in various symptoms and clinical manifestations. OC43 is a human β-coronavirus that induces mild clinical symptoms and can be safely studied in the BSL2 laboratory. Due to its low risk, OC43 can be a valuable and accessible model for understanding β-coronavirus pathogenesis. One potential target for limiting virus infectivity could be gap junction-mediated communication. This study aims to unveil the status of cell-to-cell communications through gap junctions in human β-coronavirus infection. Infection with OC43 leads to reduced expression of Cx43 in A549, a lung epithelial carcinoma cell line. Infection with this virus also shows a significant ER and oxidative stress increase. Internal localization of Cx43 is observed post-OC43 infection in the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) region, which impairs the gap junction communication between two adjacent cells, confirmed by Lucifer yellow dye transfer assay. It also affects hemichannel formation, as depicted by the EtBr uptake assay. Impairment of Cx43 trafficking and the ability to form hemichannels and functional GJIC are hampered by virus-induced Golgi apparatus disruption. Altogether, these results suggest that several physiological changes accompany OC43 infection in A549 cells and can be considered an appropriate model system for understanding the differences in gap junction communication post-viral infections. This model system can provide valuable insights for developing therapies against human β-coronavirus infections.IMPORTANCEThe enduring impact of the recent SARS-CoV-2 pandemic underscores the importance of studying human β-coronaviruses, advancing our preparedness for future coronavirus infections. As SARS-CoV-2 is highly infectious, another human β-coronavirus OC43 can be considered an experimental model. One of the crucial pathways that can be considered is gap junction communication, as it is vital for cellular homeostasis. Our study seeks to understand the changes in Cx43-mediated cell-to-cell communication during human β-coronavirus OC43 infection. In vitro studies showed downregulation of the gap junction protein Cx43 and upregulation of the endoplasmic reticulum and oxidative stress markers post-OC43 infection. Furthermore, HCoV-OC43 infection causes reduced Cx43 trafficking, causing impairment of functional hemichannel and GJIC formation by virus-mediated Golgi apparatus disruption. Overall, this study infers that OC43 infection reshapes intercellular communication, suggesting that this pathway may be a promising target for designing highly effective therapeutics against human coronaviruses by regulating Cx43 expression.

SARS-CoV-2 and Dysphagia: A Retrospective Analysis of COVID-19 Patients with Swallowing Disorders

BACKGROUND

COVID-19 can lead to impairment of neural networks involved in swallowing, since the act of swallowing is coordinated and performed by a diffuse brain network involving peripheral nerves and muscles. Dysphagia has been identified as a risk and predictive factor for the severest form of SARS-CoV-2 infection.

OBJECTIVES

To investigate the association between swallowing disorders and COVID-19 in patients hospitalized for COVID-19.

METHODS

We collected demographic data, medical information specific to dysphagia and data on medical treatments of patients with COVID-19.

RESULTS

A total of 43 hospitalized COVID-19 patients were enrolled in the study. Twenty (46%) were evaluated positive for dysphagia and 23 (54%) were evaluated negative. Neurocognitive disorders and diabetes were mostly associated with patients who resulted positive for dysphagia. Respiratory impairment caused by COVID-19 seems to be a cause of dysphagia, since all patients who needed oxygen-therapy developed symptoms of dysphagia, unlike patients who did not. In the dysphagic group, alteration of the swallowing trigger resulted in the severest form of dysphagia. An association was found between the severest form of COVID-19 and dysphagia. This group consisted predominantly of males with longer hospitalization.

CONCLUSIONS

Identification of COVID-19 patients at risk for dysphagia is crucial for better patient management.

Persistence and free chlorine disinfection of human coronaviruses and their surrogates in water

The coronavirus disease 2019 pandemic illustrates the importance of understanding the behavior and control of human pathogenic viruses in the environment. Exposure via water (drinking, bathing, and recreation) is a known route of transmission of viruses to humans, but the literature is relatively void of studies on the persistence of many viruses, especially coronaviruses, in water and their susceptibility to chlorine disinfection. To fill that knowledge gap, we evaluated the persistence and free chlorine disinfection of human coronavirus OC43 (HCoV-OC43) and its surrogates, murine hepatitis virus (MHV) and porcine transmissible gastroenteritis virus (TGEV), in drinking water and laboratory buffer using cell culture methods. The decay rate constants of human coronavirus and its surrogates in water varied, depending on virus and water matrix. In drinking water without disinfectant addition, MHV showed the largest decay rate constant (estimate ± standard error, 2.25 ± 0.09 day-1) followed by HCoV-OC43 (0.99 ± 0.12 day-1) and TGEV (0.65 ± 0.06 day-1), while in phosphate buffer without disinfectant addition, HCoV-OC43 (0.51 ± 0.10 day-1) had a larger decay rate constant than MHV (0.28 ± 0.03 day-1) and TGEV (0.24 ± 0.02 day-1). Upon free chlorine disinfection, the inactivation rates of coronaviruses were independent of free chlorine concentration and were not affected by water matrix, though they still varied between viruses. TGEV showed the highest susceptibility to free chlorine disinfection with the inactivation rate constant of 113.50 ± 7.50 mg-1 min-1 L, followed by MHV (81.33 ± 4.90 mg-1 min-1 L) and HCoV-OC43 (59.42 ± 4.41 mg-1 min-1 L).

IMPORTANCE

This study addresses an important knowledge gap on enveloped virus persistence and disinfection in water. Results have immediate practical applications for shaping evidence-based water policies, particularly in the development of disinfection strategies for pathogenic virus control.

Intrinsic factors behind long COVID: III. Persistence of SARS-CoV-2 and its components

Considerable research has been done in investigating SARS-CoV-2 infection, its characteristics, and host immune response. However, debate is still ongoing over the emergence of post-acute sequelae of SARS-CoV-2 infection (PASC). A multitude of long-lasting symptoms have been reported several weeks after the primary acute SARS-CoV-2 infection that resemble several other viral infections. Thousands of research articles have described various post-COVID-19 conditions. Yet, the evidence around these ongoing health problems, the reasons behind them, and their molecular underpinnings are scarce. These persistent symptoms are also known as long COVID-19. The persistence of SARS-CoV-2 and/or its components in host tissues can lead to long COVID. For example, the presence of viral nucleocapsid protein and RNA was detected in the skin, appendix, and breast tissues of some long COVID patients. The persistence of viral RNA was reported in multiple anatomic sites, including non-respiratory tissues such as the adrenal gland, ocular tissue, small intestine, lymph nodes, myocardium, and sciatic nerve. Distinctive viral spike sequence variants were also found in non-respiratory tissues. Interestingly, prolonged detection of viral subgenomic RNA was observed across all tissues, sometimes in multiple tissues of the same patient, which likely reflects recent but defective viral replication. Moreover, the persistence of SARS-CoV-2 RNA was noticed throughout the brain at autopsy, as late as 230 days following symptom onset among unvaccinated patients who died of severe infection. Here, we review the persistence of SARS-CoV-2 and its components as an intrinsic factor behind long COVID. We also highlight the immunological consequences of this viral persistence.

Cardiorespiratory dysautonomia in post-COVID-19 condition: Manifestations, mechanisms and management

A significant proportion of COVID-19 patients experience debilitating symptoms for months after the acute infection. According to recent estimates, approximately 1 out of 10 COVID-19 convalescents reports persistent health issues more than 3 months after initial recovery. This 'post-COVID-19 condition' may include a large variety of symptoms from almost all domains and organs, and for some patients it may mean prolonged sick-leave, homestay and strongly limited activities of daily life. In this narrative review, we focus on the symptoms and signs of post-COVID-19 condition in adults - particularly those associated with cardiovascular and respiratory systems, such as postural orthostatic tachycardia syndrome or airway disorders - and explore the evidence for chronic autonomic dysfunction as a potential underlying mechanism. The most plausible hypotheses regarding cellular and molecular mechanisms behind the wide spectrum of observed symptoms - such as lingering viruses, persistent inflammation, impairment in oxygen sensing systems and circulating antibodies directed to blood pressure regulatory components - are discussed. In addition, an overview of currently available pharmacological and non-pharmacological treatment options is presented.

The FDA-approved drug nitazoxanide is a potent inhibitor of human seasonal coronaviruses acting at postentry level: effect on the viral spike glycoprotein

Coronaviridae is recognized as one of the most rapidly evolving virus family as a consequence of the high genomic nucleotide substitution rates and recombination. The family comprises a large number of enveloped, positive-sense single-stranded RNA viruses, causing an array of diseases of varying severity in animals and humans. To date, seven human coronaviruses (HCoV) have been identified, namely HCoV-229E, HCoV-NL63, HCoV-OC43 and HCoV-HKU1, which are globally circulating in the human population (seasonal HCoV, sHCoV), and the highly pathogenic SARS-CoV, MERS-CoV and SARS-CoV-2. Seasonal HCoV are estimated to contribute to 15-30% of common cold cases in humans; although diseases are generally self-limiting, sHCoV can sometimes cause severe lower respiratory infections and life-threatening diseases in a subset of patients. No specific treatment is presently available for sHCoV infections. Herein we show that the anti-infective drug nitazoxanide has a potent antiviral activity against three human endemic coronaviruses, the Alpha-coronaviruses HCoV-229E and HCoV-NL63, and the Beta-coronavirus HCoV-OC43 in cell culture with IC50 ranging between 0.05 and 0.15 μg/mL and high selectivity indexes. We found that nitazoxanide does not affect HCoV adsorption, entry or uncoating, but acts at postentry level and interferes with the spike glycoprotein maturation, hampering its terminal glycosylation at an endoglycosidase H-sensitive stage. Altogether the results indicate that nitazoxanide, due to its broad-spectrum anti-coronavirus activity, may represent a readily available useful tool in the treatment of seasonal coronavirus infections.

Neuropathology in COVID-19 autopsies is defined by microglial activation and lesions of the white matter with emphasis in cerebellar and brain stem areas

Introduction

This study aimed to investigate microglial and macrophage activation in 17 patients who died in the context of a COVID-19 infection in 2020 and 2021.

Methods

Through immunohistochemical analysis, the lysosomal marker CD68 was used to detect diffuse parenchymal microglial activity, pronounced perivascular macrophage activation and macrophage clusters. COVID-19 patients were compared to control patients and grouped regarding clinical aspects. Detection of viral proteins was attempted in different regions through multiple commercially available antibodies.

Results

Microglial and macrophage activation was most pronounced in the white matter with emphasis in brain stem and cerebellar areas. Analysis of lesion patterns yielded no correlation between disease severity and neuropathological changes. Occurrence of macrophage clusters could not be associated with a severe course of disease or preconditions but represent a more advanced stage of microglial and macrophage activation. Severe neuropathological changes in COVID-19 were comparable to severe Influenza. Hypoxic damage was not a confounder to the described neuropathology. The macrophage/microglia reaction was less pronounced in post COVID-19 patients, but detectable i.e. in the brain stem. Commercially available antibodies for detection of SARS-CoV-2 virus material in immunohistochemistry yielded no specific signal over controls.

Conclusion

The presented microglial and macrophage activation might be an explanation for the long COVID syndrome.

Alzheimer's disease risk after COVID-19: a view from the perspective of the infectious hypothesis of neurodegeneration

In light of the rising evidence of the association between viral and bacterial infections and neurodegeneration, we aimed at revisiting the infectious hypothesis of Alzheimer's disease and analyzing the possible implications of COVID-19 neurological sequelae in long-term neurodegeneration. We wondered how SARS-CoV-2 could be related to the amyloid-β cascade and how it could lead to the pathological hallmarks of the disease. We also predict a paradigm change in clinical medicine, which now has a great opportunity to conduct prospective surveillance of cognitive sequelae and progression to dementia in people who suffered severe infections together with other risk factors for Alzheimer's disease.

Ginkgo Biloba and Long COVID: In Vivo and In Vitro Models for the Evaluation of Nanotherapeutic Efficacy

Coronavirus infections are neuroinvasive and can provoke injury to the central nervous system (CNS) and long-term illness consequences. They may be associated with inflammatory processes due to cellular oxidative stress and an imbalanced antioxidant system. The ability of phytochemicals with antioxidant and anti-inflammatory activities, such as Ginkgo biloba, to alleviate neurological complications and brain tissue damage has attracted strong ongoing interest in the neurotherapeutic management of long COVID. Ginkgo biloba leaf extract (EGb) contains several bioactive ingredients, e.g., bilobalide, quercetin, ginkgolides A-C, kaempferol, isorhamnetin, and luteolin. They have various pharmacological and medicinal effects, including memory and cognitive improvement. Ginkgo biloba, through its anti-apoptotic, antioxidant, and anti-inflammatory activities, impacts cognitive function and other illness conditions like those in long COVID. While preclinical research on the antioxidant therapies for neuroprotection has shown promising results, clinical translation remains slow due to several challenges (e.g., low drug bioavailability, limited half-life, instability, restricted delivery to target tissues, and poor antioxidant capacity). This review emphasizes the advantages of nanotherapies using nanoparticle drug delivery approaches to overcome these challenges. Various experimental techniques shed light on the molecular mechanisms underlying the oxidative stress response in the nervous system and help comprehend the pathophysiology of the neurological sequelae of SARS-CoV-2 infection. To develop novel therapeutic agents and drug delivery systems, several methods for mimicking oxidative stress conditions have been used (e.g., lipid peroxidation products, mitochondrial respiratory chain inhibitors, and models of ischemic brain damage). We hypothesize the beneficial effects of EGb in the neurotherapeutic management of long-term COVID-19 symptoms, evaluated using either in vitro cellular or in vivo animal models of oxidative stress.

Efficacy of intravenous immunoglobulin (IVIg) on COVID-19-related neurological disorders over the last 2 years: an up-to-date narrative review

Introduction

Among the clinical manifestations of SARS-CoV-2 infection, neurological features have been commonly reported and the state-of-the-art technique suggests several mechanisms of action providing a pathophysiological rationale for central and peripheral neurological system involvement. However, during the 1st months of the pandemic, clinicians were challenged to find the best therapeutic options to treat COVID-19-related neurological conditions.

Methods

We explored the indexed medical literature in order to answer the question of whether IVIg could be included as a valid weapon in the therapeutic arsenal against COVID-19-induced neurological disorders.

Results

Virtually, all reviewed studies were in agreement of detecting an acceptable to great efficacy upon IVIg employment in neurological diseases, with no or mild adverse effects. In the first part of this narrative review, the interaction of SARS-CoV-2 with the nervous system has been discussed and the IVIg mechanisms of action were reviewed. In the second part, we collected scientific literature data over the last 2 years to discuss the use of IVIg therapy in different neuro-COVID conditions, thus providing a summary of the treatment strategies and key findings.

Discussion

Intravenous immunoglobulin (IVIg) therapy is a versatile tool with multiple molecular targets and mechanisms of action that might respond to some of the suggested effects of infection through inflammatory and autoimmune responses. As such, IVIg therapy has been used in several COVID-19-related neurological diseases, including polyneuropathies, encephalitis, and status epilepticus, and results have often shown improvement of symptoms, thus suggesting IVIg treatment to be safe and effective.

Human Coronavirus OC43 as a Low-Risk Model to Study COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has had irreversible and devastating impacts on every aspect of human life. To better prepare for the next similar pandemic, a clear understanding of coronavirus biology is a prerequisite. Nevertheless, the high-risk nature of the causative agent of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), requires the use of a cumbersome biosafety level-3 (BSL-3) confinement facility. To facilitate the development of preventive and therapeutic measures against SARS-CoV-2, one of the endemic strains of low-risk coronaviruses has gained attention as a useful research alternative: human coronavirus OC43 (HCoV-OC43). In this review, its history, classification, and clinical manifestations are first summarized. The characteristics of its viral genomes, genes, and evolution process are then further explained. In addition, the host factors necessary to support the life cycle of HCoV-OC43 and the innate, as well as adaptive, immunological responses to HCoV-OC43 infection are discussed. Finally, the development of in vitro and in vivo systems to study HCoV-OC43 and its application to the discovery of potential antivirals for COVID-19 by using HCoV-OC43 models are also presented. This review should serve as a concise guide for those who wish to use HCoV-OC43 to study coronaviruses in a low-risk research setting.

Immune Functions of Astrocytes in Viral Neuroinfections

Neuroinfections of the central nervous system (CNS) can be triggered by various pathogens. Viruses are the most widespread and have the potential to induce long-term neurologic symptoms with potentially lethal outcomes. In addition to directly affecting their host cells and inducing immediate changes in a plethora of cellular processes, viral infections of the CNS also trigger an intense immune response. Regulation of the innate immune response in the CNS depends not only on microglia, which are fundamental immune cells of the CNS, but also on astrocytes. These cells align blood vessels and ventricle cavities, and consequently, they are one of the first cell types to become infected after the virus breaches the CNS. Moreover, astrocytes are increasingly recognized as a potential viral reservoir in the CNS; therefore, the immune response initiated by the presence of intracellular virus particles may have a profound effect on cellular and tissue physiology and morphology. These changes should be addressed in terms of persisting infections because they may contribute to recurring neurologic sequelae. To date, infections of astrocytes with different viruses originating from genetically distinct families, including Flaviviridae, Coronaviridae, Retroviridae, Togaviridae, Paramyxoviridae, Picomaviridae, Rhabdoviridae, and Herpesviridae, have been confirmed. Astrocytes express a plethora of receptors that detect viral particles and trigger signaling cascades, leading to an innate immune response. In this review, we summarize the current knowledge on virus receptors that initiate the release of inflammatory cytokines from astrocytes and depict the involvement of astrocytes in immune functions of the CNS.

The interplay between circadian clock and viral infections: A molecular perspective

The circadian clock influences almost every aspect of mammalian behavioral, physiological and metabolic processes. Being a hierarchical network, the circadian clock is driven by the central clock in the brain and is composed of several peripheral tissue-specific clocks. It orchestrates and synchronizes the daily oscillations of biological processes to the environment. Several pathological events are influenced by time and seasonal variations and as such implicate the clock in pathogenesis mechanisms. In context with viral infections, circadian rhythmicity is closely associated with host susceptibility, disease severity, and pharmacokinetics and efficacies of antivirals and vaccines. Leveraging the circadian molecular mechanism insights has increased our understanding of clock infection biology and proposes new avenues for viral diagnostics and therapeutics. In this chapter, we address the molecular interplay between the circadian clock and viral infections and discuss the importance of chronotherapy as a complementary approach to conventional medicines, emphasizing the significance of virus-clock studies.

Peptide microarrays coupled to machine learning reveal individual epitopes from human antibody responses with neutralizing capabilities against SARS-CoV-2

The coronavirus SARS-CoV-2 is the causative agent for the disease COVID-19. To capture the IgA, IgG, and IgM antibody response of patients infected with SARS-CoV-2 at individual epitope resolution, we constructed planar microarrays of 648 overlapping peptides that cover the four major structural proteins S(pike), N(ucleocapsid), M(embrane), and E(nvelope). The arrays were incubated with sera of 67 SARS-CoV-2 positive and 22 negative control samples. Specific responses to SARS-CoV-2 were detectable, and nine peptides were associated with a more severe course of the disease. A random forest model disclosed that antibody binding to 21 peptides, mostly localized in the S protein, was associated with higher neutralization values in cellular anti-SARS-CoV-2 assays. For antibodies addressing the N-terminus of M, or peptides close to the fusion region of S, protective effects were proven by antibody depletion and neutralization assays. The study pinpoints unusual viral binding epitopes that might be suited as vaccine candidates.

Long Covid: where we stand and challenges ahead

Post-acute sequelae of SARS-CoV-2 (PASC), also known as Post-Covid Syndrome, and colloquially as Long Covid, has been defined as a constellation of signs and symptoms which persist for weeks or months after the initial SARS-CoV-2 infection. PASC affects a wide range of diverse organs and systems, with manifestations involving lungs, brain, the cardiovascular system and other organs such as kidney and the neuromuscular system. The pathogenesis of PASC is complex and multifactorial. Evidence suggests that seeding and persistence of SARS-CoV-2 in different organs, reactivation, and response to unrelated viruses such as EBV, autoimmunity, and uncontrolled inflammation are major drivers of PASC. The relative importance of pathogenetic pathways may differ in different tissue and organ contexts. Evidence suggests that vaccination, in addition to protecting against disease, reduces PASC after breakthrough infection although its actual impact remains to be defined. PASC represents a formidable challenge for health care systems and dissecting pathogenetic mechanisms may pave the way to targeted preventive and therapeutic approaches.

Methylene blue, Mycophenolic acid, Posaconazole, and Niclosamide inhibit SARS-CoV-2 Omicron variant BA.1 infection of human airway epithelial organoids

Sublineages of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) Omicron variants continue to amass mutations in the spike (S) glycoprotein, which leads to immune evasion and rapid spread of the virus across the human population. Here we demonstrate the susceptibility of the Omicron variant BA.1 (B.1.1.529.1) to four repurposable drugs, Methylene blue (MB), Mycophenolic acid (MPA), Posaconazole (POS), and Niclosamide (Niclo) in post-exposure treatments of primary human airway cell cultures. MB, MPA, POS, and Niclo are known to block infection of human nasal and bronchial airway epithelial explant cultures (HAEEC) with the Wuhan strain, and four variants of concern (VoC), Alpha (B.1.1.7), Beta (B.1.351), Gamma (B.1.1.28), Delta (B.1.617.2) (Weiss et al., 2021, Murer et al., 2022). Our results here not only reinforce the broad anti-coronavirus effects of MB, MPA, POS and Niclo, but also demonstrate that the Omicron variant BA.1 (B.1.1.529.1) sheds infectious virus from HAEEC over at least 15 d, and maintains both intracellular and extracellular viral genomic RNA without overt toxicity, suggesting viral persistence. The data emphasize the potential of repurposable drugs against COVID-19.

A human coronavirus OC43-derived polypeptide causes neuropathic pain

Human coronaviruses have been recently implicated in neurological sequelae by insufficiently understood mechanisms. We here identify an amino acid sequence within the HCoV-OC43 p65-like protein homologous to the evolutionarily conserved motif of myelin basic protein (MBP). Because MBP-derived peptide exposure in the sciatic nerve produces pronociceptive activity in female rodents, we examined whether a synthetic peptide derived from the homologous region of HCoV-OC43 (OC43p) acts by molecular mimicry to promote neuropathic pain. OC43p, but not scrambled peptides, induces mechanical hypersensitivity in rats following intrasciatic injections. Transcriptome analyses of the corresponding spinal cords reveal upregulation of genes and signaling pathways with known nociception-, immune-, and cellular energy-related activities. Affinity capture shows the association of OC43p with an Na+ /K+ -transporting ATPase, providing a potential direct target and mechanistic insight into virus-induced effects on energy homeostasis and the sensory neuraxis. We propose that HCoV-OC43 polypeptides released during infection dysregulate normal nervous system functions through molecular mimicry of MBP, leading to mechanical hypersensitivity. Our findings might provide a new paradigm for virus-induced neuropathic pain.

Potential intestinal infection and faecal-oral transmission of human coronaviruses

Human coronaviruses (HCoVs) were first described in 1960s for patients experiencing common cold. Since then, increasing number of HCoVs have been discovered, including those causing severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and the circulating coronavirus disease 2019 (COVID‐19), which can cause fatal respiratory disease in humans on infection. HCoVs are believed to spread mainly through respiratory droplets and close contact. However, studies have shown that a large proportion of patients with HCoV infection develop gastrointestinal (GI) symptoms, and many patients with confirmed HCoV infection have shown detectable viral RNA in their faecal samples. Furthermore, multiple in vitro and in vivo animal studies have provided direct evidence of intestinal HCoV infection. These data highlight the nature of HCoV GI infection and its potential faecal‐oral transmission. Here, we summarise the current findings on GI manifestations of HCoVs. We also discuss how HCoV GI infection might occur and the current evidence to establish the occurrence of faecal‐oral transmission.

Covid-19, nervous system pathology, and Parkinson's disease: Bench to bedside

Coronavirus disease 2019 (Covid-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is primarily regarded as a respiratory disease; however, multisystemic involvement accompanied by a variety of clinical manifestations, including neurological symptoms, are commonly observed. There is, however, little evidence supporting SARS-CoV-2 infection of central nervous system cells, and neurological symptoms for the most part appear to be due to damage mediated by hypoxic/ischemic and/or inflammatory insults. In this chapter, we report evidence on candidate neuropathological mechanisms underlying neurological manifestations in Covid-19, suggesting that while there is mostly evidence against SARS-CoV-2 entry into brain parenchymal cells as a mechanism that may trigger Parkinson's disease and parkinsonism, that there are multiple means by which the virus may cause neurological symptoms.

Neurologic complications of coronavirus and other respiratory viral infections

In humans, several respiratory viruses can have neurologic implications affecting both central and peripheral nervous system. Neurologic manifestations can be linked to viral neurotropism and/or indirect effects of the infection due to endothelitis with vascular damage and ischemia, hypercoagulation state with thrombosis and hemorrhages, systemic inflammatory response, autoimmune reactions, and other damages. Among these respiratory viruses, recent and huge attention has been given to the coronaviruses, especially the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic started in 2020. Besides the common respiratory symptoms and the lung tropism of SARS-CoV-2 (COVID-19), neurologic manifestations are not rare and often present in the severe forms of the infection. The most common acute and subacute symptoms and signs include headache, fatigue, myalgia, anosmia, ageusia, sleep disturbances, whereas clinical syndromes include mainly encephalopathy, ischemic stroke, seizures, and autoimmune peripheral neuropathies. Although the pathogenetic mechanisms of COVID-19 in the various acute neurologic manifestations are partially understood, little is known about long-term consequences of the infection. These consequences concern both the so-called long-COVID (characterized by the persistence of neurological manifestations after the resolution of the acute viral phase), and the onset of new neurological symptoms that may be linked to the previous infection.

Can SARS-CoV-2 Infection Lead to Neurodegeneration and Parkinson's Disease?

The SARS-CoV-2 pandemic has affected the daily life of the worldwide population since 2020. Links between the newly discovered viral infection and the pathogenesis of neurodegenerative diseases have been investigated in different studies. This review aims to summarize the literature concerning COVID-19 and Parkinson's disease (PD) to give an overview on the interface between viral infection and neurodegeneration with regard to this current topic. We will highlight SARS-CoV-2 neurotropism, neuropathology and the suspected pathophysiological links between the infection and neurodegeneration as well as the psychosocial impact of the pandemic on patients with PD. Some evidence discussed in this review suggests that the SARS-CoV-2 pandemic might be followed by a higher incidence of neurodegenerative diseases in the future. However, the data generated so far are not sufficient to confirm that COVID-19 can trigger or accelerate neurodegenerative diseases.

Relationship between COVID-19 and movement disorders: A narrative review

BACKGROUND AND PURPOSE

The scientific literature on COVID-19 is increasingly growing.

METHODS

In this paper, we review the literature on movement disorders in the context of the COVID-19 pandemic.

RESULTS

First, there are a variety of transient movement disorders that may manifest in the acute phase of COVID-19, most often myoclonus, with more than 50 patients described in the literature. New onset parkinsonism, chorea, and tic-like behaviours have also been reported. Movement disorders as a side effect after COVID-19 vaccination are rare, occurring with a frequency of 0.00002-0.0002 depending on the product used, mostly manifesting with tremor. Current evidence for potential long-term manifestations, for example, long COVID parkinsonism, is separately discussed. Second, the pandemic has also had an impact on patients with pre-existing movement disorder syndromes, with negative effects on clinical status and overall well-being, and reduced access to medication and health care. In many parts, the pandemic has led to reorganization of the medical system, including the development of new digital solutions. The movement disorder-related evidence for this is reviewed and discussed.

CONCLUSIONS

The pandemic and the associated preventive measures have had a negative impact on the clinical status, access to health care, and overall well-being of patients with pre-existing movement disorders.

Neurological complications and infection mechanism of SARS-COV-2

Currently, SARS-CoV-2 has caused a global pandemic and threatened many lives. Although SARS-CoV-2 mainly causes respiratory diseases, growing data indicate that SARS-CoV-2 can also invade the central nervous system (CNS) and peripheral nervous system (PNS) causing multiple neurological diseases, such as encephalitis, encephalopathy, Guillain-Barré syndrome, meningitis, and skeletal muscular symptoms. Despite the increasing incidences of clinical neurological complications of SARS-CoV-2, the precise neuroinvasion mechanisms of SARS-CoV-2 have not been fully established. In this review, we primarily describe the clinical neurological complications associated with SARS-CoV-2 and discuss the potential mechanisms through which SARS-CoV-2 invades the brain based on the current evidence. Finally, we summarize the experimental models were used to study SARS-CoV-2 neuroinvasion. These data form the basis for studies on the significance of SARS-CoV-2 infection in the brain.

Radiological Manifestation of Neurological Complications in the Course of SARS-CoV-2 Infection

Many reports suggest the SARS-CoV-2 infection may result in neurological complications. A wide spectrum of clinical syndromes have been reported, including both central and peripheral nervous system. Such symptoms may be a consequence of a direct viral injury, secondary to systemic inflammatory response, autoimmune processes, ischemic lesions or combination of these. Anosmia and dysgeusia are highly prevalent in the early stage of infection. Cerebrovascular events in patients with COVID-19 have also been documented with increasing frequency. Some cases of parainfectious autoimmune neurologic manifestations concurrent with active SARS-CoV-2 infection have been described, including hemorrhagic necrotizing encephalopathy, Guillain-Barré and Miller-Fisher syndromes. There are also a few reports documenting encephalitis and acute demyelinating encephalomyelitis (ADEM) in the course of COVID-19. There is also a growing number of cases of patients after recovery from COVID-19 with psychosomatic disorders, manifesting with memory disfunction, cognitive functions disorders, depression or other affective disorders, which may lead to a decrease of intellectual functions. Many of these neurological manifestations of the infection are possible to distinguish using radiological imaging techniques. It plays a very important role in evaluating the course of COVID-19 as well as diagnosing respiratory complications and choosing a proper management of infected patients. Similarly, radiological techniques play crucial role in identifying the cause of neurological symptoms connected to SARS-CoV-2 infection, being one of the most important elements of diagnostics. Especially in case of the presence of nervous system implication, using radiological imaging techniques to monitor the emerging onset of various symptoms is crucial to assess the severity and scope of involvement. Quick diagnostic process and identifying complications as fast as possible in order to implement specific treatment can be crucial to avoid long-term secondary conditions and accelerate the recovery period. In this review, we present the most important neurological complications that may occur in the course of SARS-CoV-2 infection and summarize their radiological manifestations.

Coronavirus persistence in human respiratory tract and cell culture: An overview

Emerging human coronaviruses, including the recently identified SARS-CoV-2, are relevant respiratory pathogens due to their potential to cause epidemics with high case fatality rates, although endemic coronaviruses are also important for immunocompromised patients. Long-term coronavirus infections had been described mainly in experimental models, but it is currently evident that SARS-CoV-2 genomic-RNA can persist for many weeks in the respiratory tract of some individuals clinically recovered from coronavirus infectious disease-19 (COVID-19), despite a lack of isolation of infectious virus. It is still not clear whether persistence of such viral RNA may be pathogenic for the host and related to long-term sequelae.

In this review, we summarize evidence of SARS-CoV-2 RNA persistence in respiratory samples besides results obtained from cell culture and histopathology describing long-term coronavirus infection. We also comment on potential mechanisms of coronavirus persistence and relevance for pathogenesis.

Design and Development of Nanomaterial-Based Drug Carriers to Overcome the Blood-Brain Barrier by Using Different Transport Mechanisms

Central nervous system (CNS) diseases are the leading causes of death and disabilities in the world. It is quite challenging to treat CNS diseases efficiently because of the blood-brain barrier (BBB). It is a physical barrier with tight junction proteins and high selectivity to limit the substance transportation between the blood and neural tissues. Thus, it is important to understand BBB transport mechanisms for developing novel drug carriers to overcome the BBB. This paper introduces the structure of the BBB and its physiological transport mechanisms. Meanwhile, different strategies for crossing the BBB by using nanomaterial-based drug carriers are reviewed, including carrier-mediated, adsorptive-mediated, and receptor-mediated transcytosis. Since the viral-induced CNS diseases are associated with BBB breakdown, various neurotropic viruses and their mechanisms on BBB disruption are reviewed and discussed, which are considered as an alternative solution to overcome the BBB. Therefore, most recent studies on virus-mimicking nanocarriers for drug delivery to cross the BBB are also reviewed and discussed. On the other hand, the routes of administration of drug-loaded nanocarriers to the CNS have been reviewed. In sum, this paper reviews and discusses various strategies and routes of nano-formulated drug delivery systems across the BBB to the brain, which will contribute to the advanced diagnosis and treatment of CNS diseases.

Neurological complications of COVID-19: from pathophysiology to rehabilitation. An overview

OBJECTIVE

To evaluate how the SARS-COV2 is able to affect the nervous system, the main neurological manifestation, and the treatment used, including neurorehabilitation.

METHODS

Studies performed during the current year that fulfilled inclusion criteria were selected from PubMed, Scopus, Cochrane, and Web of Sciences databases. The search combined the terms "Covid 19," "rehabilitation/treatment," and "neurological complications."

RESULTS

The exact route by which SARS-CoV-2 can penetrate the CNS is still unknown, although a possible retrograde transynaptic pathway from peripheral nerve endings, and/or through the olfactory bulb, have been suggested. An early management of COVID-19 by a multiprofessional team is fundamental to avoid long term sequaele. Rehabilitation is recommended to improve respiratory and cardiac function, as well as to avoid long term neurological complications.

CONCLUSIONS

As no specific conclusions in term of prognosis and treatment could be done, research and consensus paper are needed to provide NeuroCovid patients with the best treatment options, including neurorehabilitation.

A Review on SARS-CoV-2-Induced Neuroinflammation, Neurodevelopmental Complications, and Recent Updates on the Vaccine Development

Coronavirus disease 2019 (COVID-19) is a devastating viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The incidence and mortality of COVID-19 patients have been increasing at an alarming rate. The mortality is much higher in older individuals, especially the ones suffering from respiratory distress, cardiac abnormalities, renal diseases, diabetes, and hypertension. Existing evidence demonstrated that SARS-CoV-2 makes its entry into human cells through angiotensin-converting enzyme 2 (ACE-2) followed by the uptake of virions through cathepsin L or transmembrane protease serine 2 (TMPRSS2). SARS-CoV-2-mediated abnormalities in particular cardiovascular and neurological ones and the damaged coagulation systems require extensive research to develop better therapeutic modalities. As SARS-CoV-2 uses its S-protein to enter into the host cells of several organs, the S-protein of the virus is considered as the ideal target to develop a potential vaccine. In this review, we have attempted to highlight the landmark discoveries that lead to the development of various vaccines that are currently under different stages of clinical progression. Besides, a brief account of various drug candidates that are being tested to mitigate the burden of COVID-19 was also covered. Further, in a dedicated section, the impact of SARS-CoV-2 infection on neuronal inflammation and neuronal disorders was discussed. In summary, it is expected that the content covered in this article help to understand the pathophysiology of COVID-19 and the impact on neuronal complications induced by SARS-CoV-2 infection while providing an update on the vaccine development.

The Impact of the COVID-19 Pandemic on Dementia Risk: Potential Pathways to Cognitive Decline

BACKGROUND

Coronavirus disease 2019 (COVID-19), the far-reaching pandemic, has infected approximately 185 million of the world's population to date. After infection, certain groups, including older adults, men, and people of color, are more likely to have adverse medical outcomes. COVID-19 can affect multiple organ systems, even among asymptomatic/mild severity individuals, with progressively worse damage for those with higher severity infections.

SUMMARY

The COVID-19 virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), primarily attaches to cells through the angiotensin-converting enzyme 2 (ACE2) receptor, a universal receptor present in most major organ systems. As SARS-CoV-2 binds to the ACE2 receptor, its bioavailability becomes limited, thus disrupting homeostatic organ function and inducing an injury cascade. Organ damage can then arise from multiple sources including direct cellular infection, overactive detrimental systemic immune response, and ischemia/hypoxia through thromboembolisms or disruption of perfusion. In the brain, SARS-CoV-2 has neuroinvasive and neurotropic characteristics with acute and chronic neurovirulent potential. In the cardiovascular system, COVID-19 can induce myocardial and systemic vascular damage along with thrombosis. Other organ systems such as the lungs, kidney, and liver are all at risk for infection damage. Key Messages: Our hypothesis is that each injury consequence has the independent potential to contribute to long-term cognitive deficits with the possibility of progressing to or worsening pre-existing dementia. Already, reports from recovered COVID-19 patients indicate that cognitive alterations and long-term symptoms are prevalent. This critical review highlights the injury pathways possible through SARS-CoV-2 infection that have the potential to increase and contribute to cognitive impairment and dementia.

NLRP3 and Infections: β-Amyloid in Inflammasome beyond Neurodegeneration

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

Long COVID or Post-acute Sequelae of COVID-19 (PASC): An Overview of Biological Factors That May Contribute to Persistent Symptoms

The novel virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a pandemic of coronavirus disease 2019 (COVID-19). Across the globe, a subset of patients who sustain an acute SARS-CoV-2 infection are developing a wide range of persistent symptoms that do not resolve over the course of many months. These patients are being given the diagnosis Long COVID or Post-acute sequelae of COVID-19 (PASC). It is likely that individual patients with a PASC diagnosis have different underlying biological factors driving their symptoms, none of which are mutually exclusive. This paper details mechanisms by which RNA viruses beyond just SARS-CoV-2 have be connected to long-term health consequences. It also reviews literature on acute COVID-19 and other virus-initiated chronic syndromes such as post-Ebola syndrome or myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) to discuss different scenarios for PASC symptom development. Potential contributors to PASC symptoms include consequences from acute SARS-CoV-2 injury to one or multiple organs, persistent reservoirs of SARS-CoV-2 in certain tissues, re-activation of neurotrophic pathogens such as herpesviruses under conditions of COVID-19 immune dysregulation, SARS-CoV-2 interactions with host microbiome/virome communities, clotting/coagulation issues, dysfunctional brainstem/vagus nerve signaling, ongoing activity of primed immune cells, and autoimmunity due to molecular mimicry between pathogen and host proteins. The individualized nature of PASC symptoms suggests that different therapeutic approaches may be required to best manage care for specific patients with the diagnosis.

Neurological pathogenesis of SARS-CoV-2 (COVID-19): from virological features to clinical symptoms

Since the worldwide outbreak of coronavirus disease 2019 (COVID-19) in 2020, various research reports and case reports have been published. It has been found that COVID-19 causes not only respiratory disorders but also thrombosis and gastrointestinal disorders, central nervous system (CNS) disorders, and peripheral neuropathy. Compared to other disorders, there are low number of research reports and low number of summaries on COVID-19-related neural disorders. Therefore, focusing on neural disorders, we outline both basic research and clinical manifestations of COVID-19-related neural disorders.

Risk factors for intracerebral hemorrhage in patients with COVID-19

Intracerebral hemorrhage (ICH) can be a devastating complication of coronavirus disease (COVID-19). We aimed to assess risk factors associated with ICH in this population. We performed a retrospective cohort study of adult patients admitted to NYU Langone Health system between March 1 and April 27 2020 with a positive nasopharyngeal swab polymerase chain reaction test result and presence of primary nontraumatic intracranial hemorrhage or hemorrhagic conversion of ischemic stroke on neuroimaging. Patients with intracranial procedures, malignancy, or vascular malformation were excluded. We used regression models to estimate odds ratios and 95% confidence intervals (OR, 95% CI) of the association between ICH and covariates. We also used regression models to determine association between ICH and mortality. Among 3824 patients admitted with COVID-19, 755 patients had neuroimaging and 416 patients were identified after exclusion criteria were applied. The mean (standard deviation) age was 69.3 (16.2), 35.8% were women, and 34.9% were on therapeutic anticoagulation. ICH occurred in 33 (7.9%) patients. Older age, non-Caucasian race, respiratory failure requiring mechanical ventilation, and therapeutic anticoagulation were associated with ICH on univariate analysis (p < 0.01 for each variable). In adjusted regression models, anticoagulation use was associated with a five-fold increased risk of ICH (OR 5.26, 95% CI 2.33-12.24, p < 0.001). ICH was associated with increased mortality (adjusted OR 2.6, 95 % CI 1.2-5.9). Anticoagulation use is associated with increased risk of ICH in patients with COVID-19. Further investigation is required to elucidate underlying mechanisms and prevention strategies in this population.

Elucidating the Neuropathologic Mechanisms of SARS-CoV-2 Infection

The current pandemic caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a public health emergency. To date, March 1, 2021, coronavirus disease 2019 (COVID-19) has caused about 114 million accumulated cases and 2.53 million deaths worldwide. Previous pieces of evidence suggest that SARS-CoV-2 may affect the central nervous system (CNS) and cause neurological symptoms in COVID-19 patients. It is also known that angiotensin-converting enzyme-2 (ACE2), the primary receptor for SARS-CoV-2 infection, is expressed in different brain areas and cell types. Thus, it is hypothesized that infection by this virus could generate or exacerbate neuropathological alterations. However, the molecular mechanisms that link COVID-19 disease and nerve damage are unclear. In this review, we describe the routes of SARS-CoV-2 invasion into the central nervous system. We also analyze the neuropathologic mechanisms underlying this viral infection, and their potential relationship with the neurological manifestations described in patients with COVID-19, and the appearance or exacerbation of some neurodegenerative diseases.

Murine-β-coronavirus-induced neuropathogenesis sheds light on CNS pathobiology of SARS-CoV2

The pandemic caused by SARS-CoV-2 has caused widespread infection and significant mortality across the globe. Combined virology perspective of SARS-CoV-2 with a deep-rooted understanding of pathophysiological and immunological processes underlying the clinical manifestations of COVID-19 is of prime importance. The characteristic symptom of COVID-19 is respiratory distress with diffused alveolar damage, but emerging evidence suggests COVID-19 might also have neurologic consequences. Dysregulated homeostasis in the lungs has proven to be fatal, but one cannot ignore that the inability to breathe might be due to defects in the respiratory control center of the brainstem. While the mechanism of pulmonary distress has been documented in the literature, awareness of neurological features and their pathophysiology is still in the nascent state. This review makes references to the neuro-immune axis and neuro-invasive potential of SARS-CoV and SARS-CoV2, as well as the prototypic H-CoV strains in human brains. Simultaneously, considerable discussion on relevant experimental evidence of mild to severe neurological manifestations of fellow neurotropic murine-β-CoVs (m-CoVs) in the mouse model will help understand the underpinning mechanisms of Neuro-COVID. In this review, we have highlighted the neuroimmunopathological processes in murine CoVs. While MHV infection in mice and SARS-CoV-2 infection in humans share numerous parallels, there are critical differences in viral recognition and viral entry. These similarities are highlighted in this review, while differences have also been emphasized. Though CoV-2 Spike does not favorably interact with murine ACE2 receptor, modification of murine SARS-CoV2 binding domain or development of transgenic ACE-2 knock-in mice might help in mediating consequential infection and understanding human CoV2 pathogenesis in murine models. While a global animal model that can replicate all aspects of the human disease remains elusive, prior insights and further experiments with fellow m-β-CoV-induced cause-effect experimental models and current human COVID-19 patients data may help to mitigate the SARS-CoV-2-induced multifactorial multi-organ failure.

Neurology and the COVID-19 Pandemic: Gathering Data for an Informed Response

PURPOSE OF REVIEW

The current coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the greatest medical crises faced by our current generation of health care providers. Although much remains to be learned about the pathophysiology of SARS-CoV-2, there is both historical precedent from other coronaviruses and a growing number of case reports and series that point to neurologic consequences of COVID-19.

RECENT FINDINGS

Olfactory/taste disturbances and increased risk of strokes and encephalopathies have emerged as potential consequences of COVID-19 infection. Evidence regarding whether these sequelae result indirectly from systemic infection or directly from neuroinvasion by SARS-CoV-2 is emerging.

SUMMARY

This review summarizes the current understanding of SARS-CoV-2 placed in context with our knowledge of other human coronaviruses. Evidence and data regarding neurologic sequelae of COVID-19 and the neuroinvasive potential of human coronaviruses are provided along with a summary of patient registries of interest to the Neurology community.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): a Systemic Infection

To date, seven identified coronaviruses (CoVs) have been found to infect humans; of these, three highly pathogenic variants have emerged in the 21st century. The newest member of this group, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first detected at the end of 2019 in Hubei province, China. Since then, this novel coronavirus has spread worldwide, causing a pandemic; the respiratory disease caused by the virus is called coronavirus disease 2019 (COVID-19). The clinical presentation ranges from asymptomatic to mild respiratory tract infections and influenza-like illness to severe disease with accompanying lung injury, multiorgan failure, and death. Although the lungs are believed to be the site at which SARS-CoV-2 replicates, infected patients often report other symptoms, suggesting the involvement of the gastrointestinal tract, heart, cardiovascular system, kidneys, and other organs; therefore, the following question arises: is COVID-19 a respiratory or systemic disease? This review aims to summarize existing data on the replication of SARS-CoV-2 in different tissues in both patients and ex vivo models.

A Comprehensive Review of Neurologic Manifestations of COVID-19 and Management of Pre-existing Neurologic Disorders in Children

Since the first reports of SARS-CoV-2 infection from China, multiple studies have been published regarding the epidemiologic aspects of COVID-19 including clinical manifestations and outcomes. The majority of these studies have focused on respiratory complications. However, recent findings have highlighted the systemic effects of the virus, including its potential impact on the nervous system. Similar to SARS-CoV-1, cellular entry of SARS-CoV-2 depends on the expression of ACE2, a receptor that is abundantly expressed in the nervous system. Neurologic manifestations in adults include cerebrovascular insults, encephalitis or encephalopathy, and neuromuscular disorders. However, the presence of these neurologic findings in the pediatric population is unclear. In this review, the potential neurotropism of SARS-CoV-2, known neurologic manifestations of COVID-19 in children, and management of preexisting pediatric neurologic conditions during the COVID-19 pandemic are discussed.

Does COVID-19 contribute to development of neurological disease?

BACKGROUND

Although coronavirus disease 2019 (COVID-19) has been associated primarily with pneumonia, recent data show that the causative agent of COVID-19, the coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can infect a large number of vital organs beyond the lungs, such as the heart, kidneys, and the brain. Thus, there is evidence showing possible retrograde transmission of the virus from the olfactory epithelium to regions of the brain stem.

METHODS

This is a literature review article. The research design method is an evidence-based rapid review. The present discourse aim is first to scrutinize and assess the available literature on COVID-19 repercussion on the central nervous system (CNS). Standard literature and database searches were implemented, gathered relevant material, and extracted information was then assessed.

RESULTS

The angiotensin-converting enzyme 2 (ACE2) receptors being the receptor for the virus, the threat to the central nervous system is expected. Neurons and glial cells express ACE2 receptors in the CNS, and recent studies suggest that activated glial cells contribute to neuroinflammation and the devastating effects of SARS-CoV-2 infection on the CNS. The SARS-CoV-2-induced immune-mediated demyelinating disease, cerebrovascular damage, neurodegeneration, and depression are some of the neurological complications discussed here.

CONCLUSION

This review correlates present clinical manifestations of COVID-19 patients with possible neurological consequences in the future, thus preparing healthcare providers for possible future consequences of COVID-19.

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

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

Neurological Complications Associated with the Blood-Brain Barrier Damage Induced by the Inflammatory Response During SARS-CoV-2 Infection

The main discussion above of the novel pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has focused substantially on the immediate risks and impact on the respiratory system; however, the effects induced to the central nervous system are currently unknown. Some authors have suggested that SARS-CoV-2 infection can dramatically affect brain function and exacerbate neurodegenerative diseases in patients, but the mechanisms have not been entirely described. In this review, we gather information from past and actual studies on coronaviruses that informed neurological dysfunction and brain damage. Then, we analyzed and described the possible mechanisms causative of brain injury after SARS-CoV-2 infection. We proposed that potential routes of SARS-CoV-2 neuro-invasion are determinant factors in the process. We considered that the hematogenous route of infection can directly affect the brain microvascular endothelium cells that integrate the blood-brain barrier and be fundamental in initiation of brain damage. Additionally, activation of the inflammatory response against the infection represents a critical step on injury induction of the brain tissue. Consequently, the virus' ability to infect brain cells and induce the inflammatory response can promote or increase the risk to acquire central nervous system diseases. Here, we contribute to the understanding of the neurological conditions found in patients with SARS-CoV-2 infection and its association with the blood-brain barrier integrity.

The Influence of Average Temperature and Relative Humidity on New Cases of COVID-19: Time-Series Analysis

BACKGROUND

The influence of meteorological factors on the transmission and spread of COVID-19 is of interest and has not been investigated.

OBJECTIVE

This study aimed to investigate the associations between meteorological factors and the daily number of new cases of COVID-19 in 9 Asian cities.

METHODS

Pearson correlation and generalized additive modeling (GAM) were performed to assess the relationships between daily new COVID-19 cases and meteorological factors (daily average temperature and relative humidity) with the most updated data currently available.

RESULTS

The Pearson correlation showed that daily new confirmed cases of COVID-19 were more correlated with the average temperature than with relative humidity. Daily new confirmed cases were negatively correlated with the average temperature in Beijing (r=-0.565, P<.001), Shanghai (r=-0.47, P<.001), and Guangzhou (r=-0.53, P<.001). In Japan, however, a positive correlation was observed (r=0.416, P<.001). In most of the cities (Shanghai, Guangzhou, Hong Kong, Seoul, Tokyo, and Kuala Lumpur), GAM analysis showed the number of daily new confirmed cases to be positively associated with both average temperature and relative humidity, especially using lagged 3D modeling where the positive influence of temperature on daily new confirmed cases was discerned in 5 cities (exceptions: Beijing, Wuhan, Korea, and Malaysia). Moreover, the sensitivity analysis showed, by incorporating the city grade and public health measures into the model, that higher temperatures can increase daily new case numbers (beta=0.073, Z=11.594, P<.001) in the lagged 3-day model.

CONCLUSIONS

The findings suggest that increased temperature yield increases in daily new cases of COVID-19. Hence, large-scale public health measures and expanded regional research are still required until a vaccine becomes widely available and herd immunity is established.

Pathophysiological Clues to How the Emergent SARS-CoV-2 Can Potentially Increase the Susceptibility to Neurodegeneration

Along with emergence of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in late 2019, a myriad of neurologic symptoms, associated with structural brain changes, were reported. In this paper, we provide evidence to critically discuss the claim that the survived patients could possibly be at increased risk for neurodegenerative diseases via various mechanisms. This virus can directly invade the brain through olfactory bulb, retrograde axonal transport from peripheral nerve endings, or via hematogenous or lymphatic routes. Infection of the neurons along with peripheral leukocytes activation results in pro-inflammatory cytokine increment, rendering the brain to neurodegenerative changes. Also, occupation of the angiotensin-converting enzyme 2 (ACE-2) with the virus may lead to a decline in ACE-2 activity, which acts as a neuroprotective factor. Furthermore, acute respiratory distress syndrome (ARDS) and septicemia induce hypoxemia and hypoperfusion, which are locally exacerbated due to the hypercoagulable state and micro-thrombosis in brain vessels, leading to oxidative stress and neurodegeneration. Common risk factors for COVID-19 and neurodegenerative diseases, such as metabolic risk factors, genetic predispositions, and even gut microbiota dysbiosis, can contribute to higher occurrence of neurodegenerative diseases in COVID-19 survivors. However, it should be considered that severity of the infection, the extent of neurologic symptoms, and the persistence of viral infection consequences are major determinants of this association. Importantly, whether this pandemic will increase the overall incidence of neurodegeneration is not clear, as a high percentage of patients with severe form of COVID-19 might probably not survive enough to develop neurodegenerative diseases.

Neuroinvasive potential of human coronavirus OC43: case report of fatal encephalitis in an immunocompromised host

Neurologic manifestations of COVID-19 include anosmia, ageusia, encephalopathy, agitation, confusion, ischemic strokes, Guillain–Barré syndrome, seizures, and hemorrhagic encephalitis. Although mechanisms of central nervous system (CNS) injury are likely diverse, direct viral invasion of the CNS has been demonstrated in case reports. Neurotropism of human coronaviruses (HCoVs) is therefore of great interest in the context of the COVID-19 pandemic. Here we present an autopsy-proven case of fatal human coronavirus (HCoV)-OC43 encephalitis in an infant with aplastic thymus and chronic T-cell lymphopenia. Clinicians should remain alert to the possibility of direct CNS invasion by human coronaviruses, including the novel pandemic SARS-CoV-2.

SARS-COV-2 (Covid-19) and male fertility: Where are we?

Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), a single-stranded RNA virus, was found to be the causal agent of the disease called coronavirus disease. During December 2019, China informed the World Health Organization (WHO) of an outbreak of cases of pneumonia of unknown etiology, which caused severe-acute respiratory distress. The disease was termed coronavirus disease 2019 (Covid-19). Due to alarming levels of spread and severity, on the 11th of March 2020, the WHO declared the outbreak as a global pandemic. As of September 14, 2020, more than 29 million cases have been reported, with over 900,000 deaths globally. Since the outbreak, although not conclusive, discoveries have been made regarding the understanding of the epidemiology, etiology, clinical features, clinical treatment, and prevention of the disease. SARS-COV-2 has been detected in saliva, respiratory fluids, blood, urine, and faeces. Findings are however controversial regarding its presence in the semen or the testis. Hence, this review aimed to further analyse the literature concerning (i) the effects of previously identified human coronaviruses on male fertility (ii) the impact of Covid-19 on male fertility and (iii) the implication for general health in terms of infection and transmission.

Neurological and Neuropsychiatric Impacts of COVID-19 Pandemic

BACKGROUND

Albeit primarily a disease of respiratory tract, the 2019 coronavirus infectious disease (COVID-19) has been found to have causal association with a plethora of neurological, neuropsychiatric and psychological effects. This review aims to analyze them with a discussion of evolving therapeutic recommendations.

METHODS

PubMed and Google Scholar were searched from 1 January 2020 to 30 May 2020 with the following key terms: "COVID-19", "SARS-CoV-2", "pandemic", "neuro-COVID", "stroke-COVID", "epilepsy-COVID", "COVID-encephalopathy", "SARS-CoV-2-encephalitis", "SARS-CoV-2-rhabdomyolysis", "COVID-demyelinating disease", "neurological manifestations", "psychosocial manifestations", "treatment recommendations", "COVID-19 and therapeutic changes", "psychiatry", "marginalised", "telemedicine", "mental health", "quarantine", "infodemic" and "social media". A few newspaper reports related to COVID-19 and psychosocial impacts have also been added as per context.

RESULTS

Neurological and neuropsychiatric manifestations of COVID-19 are abundant. Clinical features of both central and peripheral nervous system involvement are evident. These have been categorically analyzed briefly with literature support. Most of the psychological effects are secondary to pandemic-associated regulatory, socioeconomic and psychosocial changes.

CONCLUSION

Neurological and neuropsychiatric manifestations of this disease are only beginning to unravel. This demands a wide index of suspicion for prompt diagnosis of SARS-CoV-2 to prevent further complications and mortality.

Biological and Psychological Factors Determining Neuropsychiatric Outcomes in COVID-19

PURPOSE OF REVIEW

We present biological and psychological factors implicated in psychiatric manifestations of SARS-CoV-2, as well as its neuroinvasive capability and immune pathophysiology.

RECENT FINDINGS

Preexisting mental illness leads to worse clinical outcomes in COVID-19. The presence of the virus was reported in the cerebrospinal fluid (CSF) and brain tissue post-mortem. Most common psychiatric manifestations include delirium, mood disorders, anxiety disorders, and posttraumatic stress disorder. "Long-COVID" non-syndromal presentations include "brain-fogginess," autonomic instability, fatigue, and insomnia. SARS-CoV-2 infection can trigger prior vulnerabilities based on the priming of microglia and other cells, induced or perpetuated by aging and mental and physical illnesses. COVID-19 could further induce priming of neuroimmunological substrates leading to exacerbated immune response and autoimmunity targeting structures in the central nervous system (CNS), in response to minor immune activating environmental exposures, including stress, minor infections, allergens, pollutants, and traumatic brain injury.

Three-Dimensional Human Alveolar Stem Cell Culture Models Reveal Infection Response to SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the cause of a present pandemic, infects human lung alveolar type 2 (hAT2) cells. Characterizing pathogenesis is crucial for developing vaccines and therapeutics. However, the lack of models mirroring the cellular physiology and pathology of hAT2 cells limits the study. Here, we develop a feeder-free, long-term, three-dimensional (3D) culture technique for hAT2 cells derived from primary human lung tissue and investigate infection response to SARS-CoV-2. By imaging-based analysis and single-cell transcriptome profiling, we reveal rapid viral replication and the increased expression of interferon-associated genes and proinflammatory genes in infected hAT2 cells, indicating a robust endogenous innate immune response. Further tracing of viral mutations acquired during transmission identifies full infection of individual cells effectively from a single viral entry. Our study provides deep insights into the pathogenesis of SARS-CoV-2 and the application of defined 3D hAT2 cultures as models for respiratory diseases.

Neurotropism of SARS-CoV-2 and its neuropathological alterations: Similarities with other coronaviruses

A novel coronavirus (SARS-CoV-2) emerged from Wuhan, China, and spread quickly around the world. In addition to fever, cough and shortness of breath, it was confirmed that the patients also have manifestations towards the central nervous system (CNS), especially those critically ill ones. In this review, we will discuss how SARS-CoV-2 gain access to the CNS and the possible consequences. Both SARS-CoV-2 and SARS-CoV-1 in 2002 share the same receptor angiotensin-converting enzyme 2 (ACE2), which can be found in the brain and mediate the disease process. Both direct attack of SARS-CoV-2 and the abnormal immune response in the CNS would contribute to the disease. Also, there is a relationship between SARS-CoV-2 and the occurrence of acute cerebrovascular diseases.