Cellular mechanisms underlying neurological/neuropsychiatric manifestations of COVID-19

Cognitive dysfunctions in the course of SARS‑CoV‑2 virus infection, including NeuroCOVID, frontal syndrome and cytokine storm (Review)

During the coronavirus disease 2019 (COVID-19) pandemic, cognitive impairment of varying degrees of severity began to be observed in a significant percentage of patients. The present study discussed the impact of immunological processes on structural and functional changes in the central nervous system and the related cognitive disorders. The purpose of the present review was to analyse and discuss available information from the scientific literature considering the possible relationship between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral infection and cognitive impairment, including NeuroCOVID, frontal syndrome and cytokine storm. A systematic literature review was conducted using: Google Scholar, Elsevier and the PubMed database. When searching for materials, the following keywords were used: 'cognitive dysfunctions', 'SARS-CoV-2', 'COVID-19', 'Neuro-SARS2', 'NeuroCOVID', 'frontal syndrome', 'cytokine storm', 'Long COVID-19'. A total of 96 articles were included in the study. The analysis focused on the characteristics of each study's materials, methods, results and conclusions. SARS-CoV-2 infection may induce or influence existing cognitive disorders of various nature and severity. The influence of immunological factors related to the response against SARS-CoV-2 on the disturbance of cerebral perfusion, the functioning of nerve cells and the neuroprotective effect has been demonstrated. Particular importance is attached to the cytokine storm and the related difference between pro- and anti-inflammatory effects, oxidative stress, disturbances in the regulation of the hypothalamic-pituitary-adrenal axis and the stress response of the body.

Mast cell activation triggered by SARS-CoV-2 causes inflammation in brain microvascular endothelial cells and microglia

SARS-CoV-2-induced excessive inflammation in brain leads to damage of blood-brain barrier, hypoxic-ischemic injury, and neuron degeneration. The production of inflammatory cytokines by brain microvascular endothelial cells and microglia is reported to be critically associated with the brain pathology of COVID-19 patients. However, the cellular mechanisms for SARS-CoV-2-inducing activation of brain cells and the subsequent neuroinflammation remain to be fully delineated. Our research, along with others', has recently demonstrated that SARS-CoV-2-induced accumulation and activation of mast cells (MCs) in mouse lung could further induce inflammatory cytokines and consequent lung damages. Intracerebral MCs activation and their cross talk with other brain cells could induce neuroinflammation that play important roles in neurodegenerative diseases including virus-induced neuro-pathophysiology. In this study, we investigated the role of MC activation in SARS-CoV-2-induced neuroinflammation. We found that (1) SARS-CoV-2 infection triggered MC accumulation in the cerebrovascular region of mice; (2) spike/RBD (receptor-binding domain) protein-triggered MC activation induced inflammatory factors in human brain microvascular endothelial cells and microglia; (3) MC activation and degranulation destroyed the tight junction proteins in brain microvascular endothelial cells and induced the activation and proliferation of microglia. These findings reveal a cellular mechanism of SARS-CoV-2-induced neuroinflammation.

[Interaction of somatic findings and psychiatric symptoms in COVID-19. A scoping review]

An infection with SARS-CoV‑2 can affect the central nervous system, leading to neurological as well as psychiatric symptoms. In this respect, mechanisms of inflammation seem to be of much greater importance than the virus itself. This paper deals with the possible contributions of organic changes to psychiatric symptomatology and deals especially with delirium, cognitive symptoms, depression, anxiety, posttraumatic stress disorder and psychosis. Processes of neuroinflammation with infection of capillary endothelial cells and activation of microglia and astrocytes releasing high amounts of cytokines seem to be of key importance in all kinds of disturbances. They can lead to damage in grey and white matter, impairment of cerebral metabolism and loss of connectivity. Such neuroimmunological processes have been described as a organic basis for many psychiatric disorders, as affective disorders, psychoses and dementia. As the activation of the glia cells can persist for a long time after the offending agent has been cleared, this can contribute to long term sequalae of the infection.

Three Types of Demyelination, Perivenous, Confluent, and Perineuronal Nets-Rich in a COVID-19 Patient With Meningoencephalomyelitis

Neurologic symptoms are common in COVID-19, and a variety of neuropathological changes have been reported. One of the important neuropathological findings is demyelination. However, the underlying pathogenesis of demyelination remained poorly understood. We witnessed a case of COVID-19 with distinct types of demyelination in the cerebrum, medulla oblongata, and spinal canal, who died of sepsis. The postmortem examination showed the solitary massive demyelination in the medulla oblongata. The massive lesion was filled with components of perineuronal nets. In the spinal canal, confluent demyelination in bilateral lateral and dorsal funiculi was detected over the entire length from C1 to S5, which was maximum at the level of cervical spinal canal stenosis. Demyelination in the cerebrum was mainly perivenular, and augmented in the area of lacunar infarcts and dilated perivascular spaces. Considering the distribution patterns of the following three types of demyelination, the traces of viral spreading could be highlighted. Discontinuous perivenous demyelination in the cerebrum showed the result of hematogenous spreading. Longitudinal confluent demyelination of the spinal cord should be the picturesque of the trace of axonal spreading. The distribution of demyelination was possibly modified by the underlying diseases, diabetes mellitus, hypertension, and spinal canal stenosis.

Recombinant SARS-CoV-2 Spike Protein and Its Receptor Binding Domain Stimulate Release of Different Pro-Inflammatory Mediators via Activation of Distinct Receptors on Human Microglia Cells

SARS-CoV-2 infects cells via its spike (S) protein binding to its surface receptor angiotensin converting enzyme 2 (ACE2) on target cells and results in acute symptoms involving especially the lungs known as COVID-19. However, increasing evidence indicates that SARS-CoV-2 infection produces neuroinflammation associated with neurological, neuropsychiatric, and cognitive symptoms persists well past the resolution of the infection, known as post-COVID-19 sequalae or long-COVID. The neuroimmune mechanism(s) involved in long-COVID have not been adequately characterized. In this study, we show that recombinant SARS-CoV-2 full-length S protein stimulates release of pro-inflammatory IL-1b, CXCL8, IL-6, and MMP-9 from cultured human microglia via TLR4 receptor activation. Instead, recombinant receptor-binding domain (RBD) stimulates release of TNF-α, IL-18, and S100B via ACE2 signaling. These results provide evidence that SARS-CoV-2 spike protein contributes to neuroinflammation through different mechanisms that may be involved in CNS pathologies associated with long-COVID.

Merits and challenges of iPSC-derived organoids for clinical applications

Induced pluripotent stem cells (iPSCs) have entered an unprecedented state of development since they were first generated. They have played a critical role in disease modeling, drug discovery, and cell replacement therapy, and have contributed to the evolution of disciplines such as cell biology, pathophysiology of diseases, and regenerative medicine. Organoids, the stem cell-derived 3D culture systems that mimic the structure and function of organs in vitro, have been widely used in developmental research, disease modeling, and drug screening. Recent advances in combining iPSCs with 3D organoids are facilitating further applications of iPSCs in disease research. Organoids derived from embryonic stem cells, iPSCs, and multi-tissue stem/progenitor cells can replicate the processes of developmental differentiation, homeostatic self-renewal, and regeneration due to tissue damage, offering the potential to unravel the regulatory mechanisms of development and regeneration, and elucidate the pathophysiological processes involved in disease mechanisms. Herein, we have summarized the latest research on the production scheme of organ-specific iPSC-derived organoids, the contribution of these organoids in the treatment of various organ-related diseases, in particular their contribution to COVID-19 treatment, and have discussed the unresolved challenges and shortcomings of these models.

Uncovering a neurological protein signature for severe COVID-19

Coronavirus disease of 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has sparked a global pandemic with severe complications and high morbidity rate. Neurological symptoms in COVID-19 patients, and neurological sequelae post COVID-19 recovery have been extensively reported. Yet, neurological molecular signature and signaling pathways that are affected in the central nervous system (CNS) of COVID-19 severe patients remain still unknown and need to be identified. Plasma samples from 49 severe COVID-19 patients, 50 mild COVID-19 patients, and 40 healthy controls were subjected to Olink proteomics analysis of 184 CNS-enriched proteins. By using a multi-approach bioinformatics analysis, we identified a 34-neurological protein signature for COVID-19 severity and unveiled dysregulated neurological pathways in severe cases. Here, we identified a new neurological protein signature for severe COVID-19 that was validated in different independent cohorts using blood and postmortem brain samples and shown to correlate with neurological diseases and pharmacological drugs. This protein signature could potentially aid the development of prognostic and diagnostic tools for neurological complications in post-COVID-19 convalescent patients with long term neurological sequelae.

Role of SARS-CoV-2 Spike-Protein-Induced Activation of Microglia and Mast Cells in the Pathogenesis of Neuro-COVID

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). About 45% of COVID-19 patients experience several symptoms a few months after the initial infection and develop post-acute sequelae of SARS-CoV-2 (PASC), referred to as "Long-COVID," characterized by persistent physical and mental fatigue. However, the exact pathogenetic mechanisms affecting the brain are still not well-understood. There is increasing evidence of neurovascular inflammation in the brain. However, the precise role of the neuroinflammatory response that contributes to the disease severity of COVID-19 and long COVID pathogenesis is not clearly understood. Here, we review the reports that the SARS-CoV-2 spike protein can cause blood-brain barrier (BBB) dysfunction and damage neurons either directly, or via activation of brain mast cells and microglia and the release of various neuroinflammatory molecules. Moreover, we provide recent evidence that the novel flavanol eriodictyol is particularly suited for development as an effective treatment alone or together with oleuropein and sulforaphane (ViralProtek®), all of which have potent anti-viral and anti-inflammatory actions.

Unravelling Pathophysiology of Neurological and Psychiatric Complications of COVID-19 Using Brain Organoids

Neuropsychiatric manifestations of coronavirus disease 2019 (COVID-19) have been increasingly recognized. However, the pathophysiology of COVID-19 in the central nervous system remains unclear. Brain organoid models derived from human pluripotent stem cells are potentially useful for the study of complex physiological and pathological processes associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as they recapitulate cellular heterogeneity and function of individual tissues. We identified brain organoid studies that provided insight into the neurotropic properties of SARS-CoV-2. While SARS-CoV-2 was able to infect neurons, the extent of neurotropism was relatively limited. Conversely, choroidal epithelial cells consistently showed a high susceptibility to SARS-CoV-2 infection. Brain organoid studies also elucidated potential mechanism for cellular entry, demonstrated viral replication, and highlighted downstream cellular effects of SARS-CoV-2 infection. Collectively, they suggest that the neuropsychiatric manifestations of COVID-19 may be contributed by both direct neuronal invasion and indirect consequences of neuroinflammation. The use of high throughput evaluation, patient-derived organoids, and advent of "assembloids" will provide a better understanding and functional characterization of the neuropsychiatric symptoms seen in post-acute COVID-19 syndrome. With advancement of organoid technology, brain organoids offer a promising tool for unravelling pathophysiologic clues and potential therapeutic options for neuropsychiatric complications of COVID-19.

[Psychological, psychiatric and neurological aspects of COVID-19]

OBJECTIVE

To analyze neurological, psychological and psychiatric aspects of COVID-19, as well as to study the current state of the problem.

MATERIAL AND METHODS

The study included 103 patients with COVID-19. The main research method was clinical/psychopathological. To study the impact of activities related to the care of patients with COVID-19 in a hospital setting, the medical and psychological state of 197 hospital workers involved in the treatment of patients with COVID-19 was assessed. The level of anxiety distress was assessed with the Psychological Stress Scale (PSM-25), distress indicators corresponded to values of more than 100 points. The severity of anxiety and depressive symptoms was assessed using the Hospital Anxiety and Depression Scale (HADS).

RESULTS

When considering psychopathological disorders in the context of COVID-19, it is necessary to distinguish between two main groups of disorders: mental disorders during the pandemic, and mental disorders directly caused by the causative agent SARS-CoV-2. The analysis of psychological and psychiatric aspects in various periods of the initial stage of COVID-19 showed that each of them was characterized by specific features depending on the nature of the influence of different pathogenic factors. In the structure of nosogenic mental disorders in patients with COVID-19 (103 patients), the following clinical forms were identified: acute reaction to stress (9.7%), anxiety-phobic disorders (41.7%), depressive symptoms (28.1%), hyponosognosic nosogenic reactions (20.5%). At the same time, the majority of the patients had manifestations of somatogenic asthenia (93.2%). A comparative analysis of neurological and psychological/psychiatric aspects of COVID-19 showed that the main mechanisms of the impact of highly contagious coronaviruses, including the SARS-CoV-2, on the central nervous system are: cerebral thrombosis and cerebral thromboembolism, damage to the neurovascular unit, neurodegeneration, including that induced by cytokines, and immune-mediated demyelinating nerve damage.

CONCLUSION

Neurological and psychological/psychiatric aspects of COVID-19 should be taken into account both at the stage of disease treatment and in the post-infection period due to the pronounced neurotropism of SARS-CoV-2 and its effect on the neurovascular unit. Along with helping patients, an important aspect is the preservation of the mental health of medical personnel working in hospitals for infectious diseases, due to special working conditions and a high level of professional stress.

Shared genetics and causal associations between COVID-19 and multiple sclerosis

Neuroinflammation caused by COVID-19 negatively impacts brain metabolism and function, while pre-existing brain pathology may contribute to individuals' vulnerability to the adverse consequences of COVID-19. We used summary statistics from genome-wide association studies (GWAS) to perform Mendelian randomization (MR) analyses, thus assessing potential associations between multiple sclerosis (MS) and two COVID-19 outcomes (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] infection and COVID-19 hospitalization). Genome-wide risk genes were compared between the GWAS datasets on hospitalized COVID-19 and MS. Literature-based analysis was conducted to construct molecular pathways connecting MS and COVID-19. We found that genetic liability to MS confers a causal effect on hospitalized COVID-19 (odd ratio [OR]: 1.09, 95% confidence interval: 1.03-1.16) but not on SARS-CoV-2 infection (1.03, 1.00-1.05). Genetic liability to hospitalized COVID-19 confers a causal effect on MS (1.15, 1.02-1.30). Hospitalized COVID-19 and MS share five risk genes within two loci, including TNFAIP8, HSD17B4, CDC37, PDE4A, and KEAP1. Pathway analysis identified a panel of immunity-related genes that may mediate the links between MS and COVID-19. Our study suggests that MS was associated with a 9% increased risk for COVID-19 hospitalization, while hospitalized COVID-19 was associated with a 15% increased risk for MS. Immunity-related pathways may underlie the link between MS on COVID-19.

Genetics of COVID-19 and myalgic encephalomyelitis/chronic fatigue syndrome: a systematic review

COVID‐19 and ME/CFS present with some similar symptoms, especially physical and mental fatigue. In order to understand the basis of these similarities and the possibility of underlying common genetic components, we performed a systematic review of all published genetic association and cohort studies regarding COVID‐19 and ME/CFS and extracted the genes along with the genetic variants investigated. We then performed gene ontology and pathway analysis of those genes that gave significant results in the individual studies to yield functional annotations of the studied genes using protein analysis through evolutionary relationships (PANTHER) VERSION 17.0 software. Finally, we identified the common genetic components of these two conditions. Seventy‐one studies for COVID‐19 and 26 studies for ME/CFS were included in the systematic review in which the expression of 97 genes for COVID‐19 and 429 genes for ME/CFS were significantly affected. We found that ACE, HLA‐A, HLA‐C, HLA‐DQA1, HLA‐DRB1, and TYK2 are the common genes that gave significant results. The findings of the pathway analysis highlight the contribution of inflammation mediated by chemokine and cytokine signaling pathways, and the T cell activation and Toll receptor signaling pathways. Protein class analysis revealed the contribution of defense/immunity proteins, as well as protein‐modifying enzymes. Our results suggest that the pathogenesis of both syndromes could involve some immune dysfunction.

Vestibular disorders in patients after COVID-19 infection

Introduction

The COVID-19 clinical symptoms are primarily related to the respiratory system but may also be involved in many others, including the nervous system. Recently, vertigo or dizziness has been described as one of the clinical manifestations and possible complications of COVID-19.

Materials and methods

This clinical study was designed to describe the otorhinolaryngological evaluation and videonystagmographic (VNG) findings in patients with an antecedent of COVID-19 infection in the last 6 months. In this study, we sought to investigate the presence of persistent vestibular damage in healed COVID-19 patients and to determine the origin of vertigo by conducting a comprehensive vestibular examination. To evaluate the association precisely, an otoneurological assessement was conducted on all participants. The study group included 58 patients aged 23–75 years with vertigo, who were diagnosed with COVID-19 infection 6 months before the examination. Each participant was submitted to an evaluation consisting of anamnesis, otorhinolaryngological evaluation, and VNG.

Results

Spontaneous nystagmus with closed eyes was reported in 8 patients (13.8%). Positional nystagmus was observed in 15 patients (24.1%). Asymmetrical optokinetic nystagmus was observed in 18 patients (31%). A distorted record in the tracking pendulum test was present in 23 patients (39.7%). Square waves were observed in 34 COVID-19 patients (58.6%). Unilateral weakness (UW) was observed in 23 subjects (39.7%); among those with UW, 22 patients (95.7%) also demonstrated directional preponderance contralateral to the UW. Another 16 patients (27.6%) presented only directional advantage. The post-caloric recruitment was present in 38% patients.

Conclusion

Patients who had been diagnosed with COVID-19 seem to be more likely to suffer from vertigo/dizziness and to compensate more slowly. COVID-19 infection may cause inner ear damage and lead to vestibular dysfunction. The role of the central nervous system in the onset of equilibrium disorders should be considered. The presence of vertigo of central origin may indicate the neurotropic effect of SARS-CoV-2 following COVID-19. Imbalance may be the only symptom of COVID-19 and may also be a late complication of the disease due to post-infectious inflammation of the nervous tissue. Comprehensive studies are needed to investigate whether COVID-19 can cause long-term vestibular deficits.

SARS-CoV-2 infection in cardiovascular disease: Unmet need of stem cell models

This review aims to summarise new approaches in SARS-CoV-2-related research in cardiology. We provide a head-to-head comparison of models, such as animal research and human pluripotent stem cells, to investigate the pathomechanisms of COVID-19 and find an efficient therapy. In vivo methods were useful for studying systemic processes of the disease; however, due to differences in animal and human biology, the clinical translation of the results remains a complex task. In vitro stem cell research makes cellular events more observable and effective for finding new drugs and therapies for COVID-19, including the use of stem cells. Furthermore, multicellular 3D organoids even make it possible to observe the effects of drugs to treat SARS-CoV-2 infection in human organ models.

Encephalitis in Patients with COVID-19: A Systematic Evidence-Based Analysis

Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) predominantly infects the respiratory system, several investigations have shown the involvement of the central nervous system (CNS) along the course of the illness, with encephalitis being one of the symptoms. The objective of this systematic review was to evaluate the characteristics (clinical, neuro-radiological aspects, and laboratory features) and outcomes of encephalitis in COVID-19 patients. PubMed, Scopus, and Google Scholar databases were searched from 1 December 2019 until 21 July 2022 to identify case reports and case series published on COVID-19 associated with encephalitis. The quality of the included studies was assessed by the Joanna Briggs Institute critical appraisal checklists. This systematic review included 79 studies, including 91 COVID-19 patients (52.7% male) experiencing encephalitis, where 85.6% were adults (49.3 ± 20.2 years), and 14.4% were children (11.2 ± 7.6 years). RT-PCR was used to confirm 92.2% of the COVID-19 patients. Encephalitis-related symptoms were present in 78.0% of COVID-19 patients at the time of diagnosis. In these encephalitis patients, seizure (29.5%), confusion (23.2%), headache (20.5%), disorientation (15.2%), and altered mental status (11.6%) were the most frequently reported neurologic manifestations. Looking at the MRI, EEG, and CSF findings, 77.6%, 75.5%, and 64.1% of the patients represented abnormal results. SARS-CoV-2-associated or -mediated encephalitis were the most common type observed (59.3%), followed by autoimmune encephalitis (18.7%). Among the included patients, 66.7% were discharged (37.8% improved and 28.9% fully recovered), whereas 20.0% of the reported COVID-19-positive encephalitis patients died. Based on the quality assessment, 87.4% of the studies were of high quality. Although in COVID-19, encephalitis is not a typical phenomenon, SARS-CoV-2 seems like a neuropathogen affecting the brain even when there are no signs of respiratory illness, causing a high rate of disability and fatality.

SARS-CoV-2 consequences for mental health: Neuroinflammatory pathways linking COVID-19 to anxiety and depression

The coronavirus disease 2019 (COVID-19) pandemic has been linked to an increased prevalence of mental health disorders, particularly anxiety and depression. Moreover, the COVID-19 pandemic has caused stress in people worldwide due to several factors, including fear of infection; social isolation; difficulty in adapting to new routines; lack of coping methods; high exposure to social media, misinformation, and fake reports; economic impact of the measures implemented to slow the contagion and concerns regarding the disease pathogenesis. COVID-19 patients have elevated levels of pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, and other inflammation-related factors. Furthermore, invasion of the central nervous system by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may potentially contribute to neuroinflammatory alterations in infected individuals. Neuroinflammation, a consequence of psychological stress due to the COVID-19 pandemic, may also play a role in the development of anxiety and depressive symptoms in the general population. Considering that neuroinflammation plays a significant role in the pathophysiology of depression and anxiety, this study investigated the effects of SARS-CoV-2 on mental health and focused on the impact of the COVID-19 pandemic on the neuroinflammatory pathways.

Potential role of astrocyte angiotensin converting enzyme 2 in the neural transmission of COVID-19 and a neuroinflammatory state induced by smoking and vaping

Background

Knowledge of the entry receptors responsible for SARS-CoV-2 is key to understand the neural transmission and pathogenesis of COVID-19 characterized by a neuroinflammatory scenario. Understanding the brain distribution of angiotensin converting enzyme 2 (ACE2), the primary entry receptor for SARS-CoV-2, remains mixed. Smoking has been shown as a risk factor for COVID-19 severity and it is not clear how smoking exacerbates the neural pathogenesis in smokers.

Methods

Immunohistochemistry, real-time PCR and western blot assays were used to systemically examine the spatial-, cell type- and isoform-specific expression of ACE2 in mouse brain and primary cultured brain cells. Experimental smoking exposure was conducted to evaluate the effect of smoking on brain expression.

Results

We observed ubiquitous expression of ACE2 but uneven brain distribution, with high expression in the cerebral microvasculature, medulla oblongata, hypothalamus, subventricular zones, and meninges around medulla oblongata and hypothalamus. Co-staining with cell type-specific markers demonstrates ACE2 is primarily expressed in astrocytes around the microvasculature, medulla oblongata, hypothalamus, ventricular and subventricular zones of cerebral ventricles, and subependymal zones in rhinoceles and rostral migratory streams, radial glial cells in the lateral ventricular zones, tanycytes in the third ventricle, epithelial cells and stroma in the cerebral choroid plexus, as well as cerebral pericytes, but rarely detected in neurons and cerebral endothelial cells. ACE2 expression in astrocytes is further confirmed in primary cultured cells. Furthermore, isoform-specific analysis shows astrocyte ACE2 has the peptidase domain responsible for SARS-CoV-2 entry, indicating astrocytes are indeed vulnerable to SARS-CoV-2 infection. Finally, our data show experimental tobacco smoking and electronic nicotine vaping exposure increase proinflammatory and/or immunomodulatory cytokine IL-1a, IL-6 and IL-5 without significantly affecting ACE2 expression in the brain, suggesting smoking may pre-condition a neuroinflammatory state in the brain.

Conclusions

The present study demonstrates a spatial- and cell type-specific expression of ACE2 in the brain, which might help to understand the acute and lasting post-infection neuropsychological manifestations in COVID-19 patients. Our data highlights a potential role of astrocyte ACE2 in the neural transmission and pathogenesis of COVID-19. This also suggests a pre-conditioned neuroinflammatory and immunocompromised scenario might attribute to exacerbated COVID-19 severity in the smokers.

A qualitative analysis of literature reporting and linking psychosis to COVID-19 infection. Findings from a postgraduate journal club

Acute exacerbations of psychosis have been reported with COVID-19 infection and medications used for its treatment. Terms "psychosis", "psychotic", "COVID-19″ and "coronavirus" were searched on "PubMed" and "GOOGLE SCHOLAR", yielding 84 articles. 14 case reports were selected based on pre-defined criteria and analyzed. Among selected articles,10 attributed psychosis to COVID-19 infection. In 3 articles, psychosis was diagnosed despite concurrent delirium. In 8 and 3 articles respectively, a clear temporal demarcation of psychosis and COVID-19 infection and steroid use was not described. Psychosis can occur secondary to GMC, or exposure to medication. Due process should be followed to ascertain the same.

INTRODUCTION

Neurotropic coronavirus infection is associated with numerous neurological and neuropsychiatric manifestations. Such presentations before, during and after the infection have been reported. Among these presentations, acute exacerbations of psychosis have been reportedly linked with COVID-19 infection and medications used for its treatment.

METHODOLOGY

Search engines "PubMed" AND "GOOGLE SCHOLAR" were searched using specific search terms during June 2021. Out of 84 articles that came up, we selected 14 articles based on pre-determined inclusion and exclusion criteria. Selected articles were analysed and discussed in the departmental journal club.

RESULTS

In 10 articles, diagnosis of psychosis was attributed to COVID-19 infection. In 3 of those articles, despite reporting concurrent delirium like presentation, diagnosis was still reported as psychosis. In 8 articles, the temporal correlation between onset of psychosis, onset of COVID-19 was not clearly demarcated. In 3 articles, clear demarcation between psychosis associated with steroid use and with a general medical condition (COVID-19) was not clearly presented. Only 2 articles did mention using a structured diagnostic system. In patients (3/17) with prior history of psychiatric illness, diagnosis was reported as relapse of psychosis (2/17), without specifying the criteria used for diagnosing a relapse.

CONCLUSION

Acute exacerbation of psychosis can occur secondary to a general medical condition (GMC), or after exposure to a medication. However, due process should be followed to ascertain that the psychosis is indeed secondary to a GMC, or a medication, and not a de-novo presentation, or delirium.

Possible Mechanisms Underlying Neurological Post-COVID Symptoms and Neurofeedback as a Potential Therapy

Theoretical considerations related to neurological post-COVID complications have become a serious issue in the COVID pandemic. We propose 3 theoretical hypotheses related to neurological post-COVID complications. First, pathophysiological processes responsible for long-term neurological complications caused by COVID-19 might have 2 phases: (1) Phase of acute Sars-CoV-2 infection linked with the pathogenesis responsible for the onset of COVID-19-related neurological complications and (2) the phase of post-acute Sars-CoV-2 infection linked with the pathogenesis responsible for long-lasting persistence of post-COVID neurological problems and/or exacerbation of another neurological pathologies. Second, post-COVID symptoms can be described and investigated from the perspective of dynamical system theory exploiting its fundamental concepts such as system parameters, attractors and criticality. Thirdly, neurofeedback may represent a promising therapy for neurological post-COVID complications. Based on the current knowledge related to neurofeedback and what is already known about neurological complications linked to acute COVID-19 and post-acute COVID-19 conditions, we propose that neurofeedback modalities, such as functional magnetic resonance-based neurofeedback, quantitative EEG-based neurofeedback, Othmer's method of rewarding individual optimal EEG frequency and heart rate variability-based biofeedback, represent a potential therapy for improvement of post-COVID symptoms.

Neurological complications associated with Covid-19; molecular mechanisms and therapeutic approaches

With the progression of investigations on the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), neurological complications have emerged as a critical aspect of the ongoing coronavirus disease 2019 (Covid‐19) pandemic. Besides the well‐known respiratory symptoms, many neurological manifestations such as anosmia/ageusia, headaches, dizziness, seizures, and strokes have been documented in hospitalised patients. The neurotropism background of coronaviruses has led to speculation that the neurological complications are caused by the direct invasion of SARS‐CoV‐2 into the nervous system. This invasion is proposed to occur through the infection of peripheral nerves or via systemic blood circulation, termed neuronal and haematogenous routes of invasion, respectively. On the other hand, aberrant immune responses and respiratory insufficiency associated with Covid‐19 are suggested to affect the nervous system indirectly. Deleterious roles of cytokine storm and hypoxic conditions in blood‐brain barrier disruption, coagulation abnormalities, and autoimmune neuropathies are well investigated in coronavirus infections, as well as Covid‐19. Here, we review the latest discoveries focussing on possible molecular mechanisms of direct and indirect impacts of SARS‐CoV‐2 on the nervous system and try to elucidate the link between some potential therapeutic strategies and the molecular pathways.

Human Brain Organoids as an In Vitro Model System of Viral Infectious Diseases

Brain organoids, or brainoids, have shown great promise in the study of central nervous system (CNS) infection. Modeling Zika virus (ZIKV) infection in brain organoids may help elucidate the relationship between ZIKV infection and microcephaly. Brain organoids have been used to study the pathogenesis of SARS-CoV-2, human immunodeficiency virus (HIV), HSV-1, and other viral infections of the CNS. In this review, we summarize the advances in the development of viral infection models in brain organoids and their potential application for exploring mechanisms of viral infections of the CNS and in new drug development. The existing limitations are further discussed and the prospects for the development and application of brain organs are prospected.

Could SARS-CoV-2 Spike Protein Be Responsible for Long-COVID Syndrome?

SARS-CoV-2 infects cells via its spike protein binding to its surface receptor on target cells and results in acute symptoms involving especially the lungs known as COVID-19. However, increasing evidence indicates that many patients develop a chronic condition characterized by fatigue and neuropsychiatric symptoms, termed long-COVID. Most of the vaccines produced so far for COVID-19 direct mammalian cells via either mRNA or an adenovirus vector to express the spike protein, or administer recombinant spike protein, which is recognized by the immune system leading to the production of neutralizing antibodies. Recent publications provide new findings that may help decipher the pathogenesis of long-COVID. One paper reported perivascular inflammation in brains of deceased patients with COVID-19, while others showed that the spike protein could damage the endothelium in an animal model, that it could disrupt an in vitro model of the blood-brain barrier (BBB), and that it can cross the BBB resulting in perivascular inflammation. Moreover, the spike protein appears to share antigenic epitopes with human molecular chaperons resulting in autoimmunity and can activate toll-like receptors (TLRs), leading to release of inflammatory cytokines. Moreover, some antibodies produced against the spike protein may not be neutralizing, but may change its conformation rendering it more likely to bind to its receptor. As a result, one wonders whether the spike protein entering the brain or being expressed by brain cells could activate microglia, alone or together with inflammatory cytokines, since protective antibodies could not cross the BBB, leading to neuro-inflammation and contributing to long-COVID. Hence, there is urgent need to better understand the neurotoxic effects of the spike protein and to consider possible interventions to mitigate spike protein-related detrimental effects to the brain, possibly via use of small natural molecules, especially the flavonoids luteolin and quercetin.

HIV, HSV, SARS-CoV-2 and Ebola Share Long-Term Neuropsychiatric Sequelae

Long COVID, in which disease-related symptoms persist for months after recovery, has led to a revival of the discussion of whether neuropsychiatric long-term symptoms after viral infections indeed result from virulent activity or are purely psychological phenomena. In this review, we demonstrate that, despite showing differences in structure and targeting, many viruses have highly similar neuropsychiatric effects on the host. Herein, we compare severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), human immunodeficiency virus 1 (HIV-1), Ebola virus disease (EVD), and herpes simplex virus 1 (HSV-1). We provide evidence that the mutual symptoms of acute and long-term anxiety, depression and post-traumatic stress among these viral infections are likely to result from primary viral activity, thus suggesting that these viruses share neuroinvasive strategies in common. Moreover, it appears that secondary induced environmental stress can lead to the emergence of psychopathologies and increased susceptibility to viral (re)infection in infected individuals. We hypothesize that a positive feedback loop of virus-environment-reinforced systemic responses exists. It is surmised that this cycle of primary virulent activity and secondary stress-induced reactivation, may be detrimental to infected individuals by maintaining and reinforcing the host's immunocompromised state of chronic inflammation, immunological strain, and maladaptive central-nervous-system activity. We propose that this state can lead to perturbed cognitive processing and promote aversive learning, which may manifest as acute, long-term neuropsychiatric illness.

Neurological update: COVID-19

Coronavirus Disease 2019 is predominantly a disorder of the respiratory system, but neurological complications have been recognised since early in the pandemic. The major pathophysiological processes leading to neurological damage in COVID-19 are cerebrovascular disease, immunologically mediated neurological disorders and the detrimental effects of critical illness on the nervous system. It is still unclear whether direct invasion of the nervous system by the Severe Acute Respiratory Syndrome Coronavirus 2 occurs; given the vast numbers of people infected at this point, this uncertainty suggests that nervous system infection is unlikely to represent a significant issue if it occurs at all. In this review, we explore what has been learnt about the neurological complications of COVID-19 over the course of the pandemic, and by which mechanisms these complications most commonly occur.

SARS-CoV-2 Spike Glycoprotein S1 Induces Neuroinflammation in BV-2 Microglia

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

Highly efficient intercellular spreading of protein misfolding mediated by viral ligand-receptor interactions

Protein aggregates associated with neurodegenerative diseases have the ability to transmit to unaffected cells, thereby templating their own aberrant conformation onto soluble homotypic proteins. Proteopathic seeds can be released into the extracellular space, secreted in association with extracellular vesicles (EV) or exchanged by direct cell-to-cell contact. The extent to which each of these pathways contribute to the prion-like spreading of protein misfolding is unclear. Exchange of cellular cargo by both direct cell contact or via EV depends on receptor-ligand interactions. We hypothesized that enabling these interactions through viral ligands enhances intercellular proteopathic seed transmission. Using different cellular models propagating prions or pathogenic Tau aggregates, we demonstrate that vesicular stomatitis virus glycoprotein and SARS-CoV-2 spike S increase aggregate induction by cell contact or ligand-decorated EV. Thus, receptor-ligand interactions are important determinants of intercellular aggregate dissemination. Our data raise the possibility that viral infections contribute to proteopathic seed spreading by facilitating intercellular cargo transfer.

Neuropsychiatric Disorders and COVID-19: What We Know So Far

SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2) affects the central nervous system (CNS), which is shown in a significant number of patients with neurological events. In this study, an updated literature review was carried out regarding neurological disorders in COVID-19. Neurological symptoms are more common in patients with severe infection according to their respiratory status and divided into three categories: (1) CNS manifestations; (2) cranial and peripheral nervous system manifestations; and (3) skeletal muscle injury manifestations. Patients with pre-existing cerebrovascular disease are at a higher risk of admission to the intensive care unit (ICU) and mortality. The neurological manifestations associated with COVID-19 are of great importance, but when life-threatening abnormal vital signs occur in severely ill COVID-19 patients, neurological problems are usually not considered. It is crucial to search for new treatments for brain damage, as well as for alternative therapies that recover the damaged brain and reduce the inflammatory response and its consequences for other organs. In addition, there is a need to diagnose these manifestations as early as possible to limit long-term consequences. Therefore, much research is needed to explain the involvement of SARS-CoV-2 causing these neurological symptoms because scientists know zero about it.

SARS-CoV-2 invasion of the central nervous: a brief review

There is increasing evidence of the ability of the novel coronavirus to invade the central nervous system (CNS). But how does a respiratory virus invade the highly protected CNS? Here, we reviewed available literature and case reports to determine CNS involvement in COVID-19, and to identify potential regions of the brain that may be affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its possible route of entry into the brain to identify its pathogenicity. Based on the symptoms, the parietal lobe and the cerebellum are the likely targets of SARS-CoV-2; however, further work is needed to elucidate this. The presence of ACE2, used by SARS-CoV-2 for cell entry, in the brain as well as detection of the virus in the cerebrospinal fluid, further assert that SARS-COV-2 targets the brain, and therefore, medical practitioners should take that into account when dealing with patients suffering from COVID-19.

COVID-19 in Children: Expressions of Type I/II/III Interferons, TRIM28, SETDB1, and Endogenous Retroviruses in Mild and Severe Cases

Children with the new coronavirus disease 2019 (COVID-19) have milder symptoms and a better prognosis than adult patients. Several investigations assessed type I, II, and III interferon (IFN) signatures in SARS-CoV-2 infected adults, however no data are available for pediatric patients. TRIM28 and SETDB1 regulate the transcription of multiple genes involved in the immune response as well as of human endogenous retroviruses (HERVs). Exogenous viral infections can trigger the activation of HERVs, which in turn can induce inflammatory and immune reactions. Despite the potential cross-talks between SARS-CoV-2 infection and TRIM28, SETDB1, and HERVs, information on their expressions in COVID-19 patients is lacking. We assessed, through a PCR real time Taqman amplification assay, the transcription levels of six IFN-I stimulated genes, IFN-II and three of its sensitive genes, three IFN-lIIs, as well as of TRIM28, SETDB1, pol genes of HERV-H, -K, and -W families, and of env genes of Syncytin (SYN)1, SYN2, and multiple sclerosis-associated retrovirus (MRSV) in peripheral blood from COVID-19 children and in control uninfected subjects. Higher expression levels of IFN-I and IFN-II inducible genes were observed in 36 COVID-19 children with mild or moderate disease as compared to uninfected controls, whereas their concentrations decreased in 17 children with severe disease and in 11 with multisystem inflammatory syndrome (MIS-C). Similar findings were found for the expression of TRIM-28, SETDB1, and every HERV gene. Positive correlations emerged between the transcriptional levels of type I and II IFNs, TRIM28, SETDB1, and HERVs in COVID-19 patients. IFN-III expressions were comparable in each group of subjects. This preserved induction of IFN-λs could contribute to the better control of the infection in children as compared to adults, in whom IFN-III deficiency has been reported. The upregulation of IFN-I, IFN-II, TRIM28, SETDB1, and HERVs in children with mild symptoms, their declines in severe cases or with MIS-C, and the positive correlations of their transcription in SARS-CoV-2-infected children suggest that they may play important roles in conditioning the evolution of the infection.

Novel Scalable and Simplified System to Generate Microglia-Containing Cerebral Organoids From Human Induced Pluripotent Stem Cells

Human cerebral organoid (CO) is a three-dimensional (3D) cell culture system that recapitulates the developing human brain. While CO has proved an invaluable tool for studying neurological disorders in a more clinically relevant matter, there have still been several shortcomings including CO variability and reproducibility as well as lack of or underrepresentation of certain cell types typically found in the brain. As the technology to generate COs has continued to improve, more efficient and streamlined protocols have addressed some of these issues. Here we present a novel scalable and simplified system to generate microglia-containing CO (MCO). We characterize the cell types and dynamic development of MCOs and validate that these MCOs harbor microglia, astrocytes, neurons, and neural stem/progenitor cells, maturing in a manner that reflects human brain development. We introduce a novel technique for the generation of embryoid bodies (EBs) directly from induced pluripotent stem cells (iPSCs) that involves simplified steps of transitioning directly from 3D cultures as well as orbital shaking culture in a standard 6-well culture plate. This allows for the generation of MCOs with an easy-to-use system that is affordable and accessible by any general lab.

Molecular Mechanisms of Palmitic Acid Augmentation in COVID-19 Pathologies

The coronavirus disease 2019 (COVID-19) pandemic has claimed over 2.7 million lives globally. Obesity has been associated with increased severity and mortality of COVID-19. However, the molecular mechanisms by which obesity exacerbates COVID-19 pathologies are not well-defined. The levels of free fatty acids (FFAs) are elevated in obese subjects. This study was therefore designed to examine how excess levels of different FFAs may affect the progression of COVID-19. Biological molecules associated with palmitic acid (PA) and COVID-19 were retrieved from QIAGEN Knowledge Base, and Ingenuity Pathway Analysis tools were used to analyze these datasets and explore the potential pathways affected by different FFAs. Our study found that one of the top 10 canonical pathways affected by PA was the coronavirus pathogenesis pathway, mediated by key inflammatory mediators, including PTGS2; cytokines, including IL1β and IL6; chemokines, including CCL2 and CCL5; transcription factors, including NFκB; translation regulators, including EEF1A1; and apoptotic mediators, including BAX. In contrast, n-3 fatty acids may attenuate PA's activation of the coronavirus pathogenesis pathway by inhibiting the activity of such mediators as IL1β, CCL2, PTGS2, and BAX. Furthermore, PA may modulate the expression of ACE2, the main cell surface receptor for the SARS-CoV-2 spike protein.