Enabling mRNA medicine for brain tumors

mRNA is a new class of drugs that has the potential to revolutionize the treatment of brain tumors. Thanks to the COVID-19 mRNA vaccines and numerous therapy-based clinical trials, it is now clear that lipid nanoparticles (LNPs) are a clinically viable means to deliver RNA therapeutics. However, LNP-mediated mRNA delivery to brain tumors remains elusive. Over the past decade, numerous studies have shown that tumor cells communicate with each other via small extracellular vesicles, which are around 100 nm in diameter and consist of lipid bilayer membrane similar to synthetic lipidbased nanocarriers. We hypothesized that rationally designed LNPs based on extracellular vesicle mimicry would enable efficient delivery of RNA therapeutics to brain tumors without undue toxicity. We synthesized LNPs using four components similar to the formulation used in the mRNA COVID19 vaccines (Moderna and Pfizer): ionizable lipid, cholesterol, helper lipid and polyethylene glycol (PEG)-lipid. For the in vitro screen, we tested ten classes of helper lipids based on their abundance in extracellular vesicle membranes, commercial availability, and large-scale production feasibility while keeping rest of the LNP components unchanged. The transfection kinetics of GFP mRNA encapsulated in LNPs and doped with 16 mol% of helper lipids was tested using GL261, U87 and SIM-A9 cell lines. Several LNP formations resulted in stable transfection (upto 5 days) of GFP mRNA in all the cell lines tested in vitro. The successful LNP candidates (enabling >80% transfection efficacy) were then tested in vivo to deliver luciferase mRNA to brain tumors via intrathecal administration in a syngeneic glioblastoma (GBM) mouse model, which confirmed luciferase expression in brain tumors in the cortex. LNPs were then tested to deliver Cre recombinase mRNA in syngeneic GBM mouse model genetically modified to express tdTomato under LoxP marker cassette that enabled identification of LNP targeted cells. mRNA was successfully delivered to tumor cells (70-80% transfected) and a range of different cells in the tumor microenvironment, including tumor-associated macrophages (80-90% transfected), neurons (31- 40% transfected), neural stem cells (39-62% transfected), oligodendrocytes (70-80% transfected) and astrocytes (44-76% transfected). Then, LNP formulations were assessed for delivering Cas9 mRNA and CD81 sgRNA (model protein) in murine syngeneic GBM model to enable gene editing in brain tumor cells. Sanger sequencing showed that CRISPR-Cas9 editing was successful in ~94% of brain tumor cells in vivo. In conclusion, we have developed a library of safe LNPs that can transfect GBM cells in vivo with high efficacy. This technology can potentially be used to develop novel mRNA therapies for GBM by delivering single or multiple mRNAs and holds great potential as a tool to study brain tumor biology.

NO CSF BIOMARKER EVIDENCE OF PERSISTING CNS INFECTION AFTER SARS-CoV-2 INFECTION

Background: Neurocognitive symptoms are common in acute as well as convalescent (post-acute sequelae of COVID-19 [PASC]) COVID-19, but mechanisms of CNS pathogenesis are unclear. The aim of this study was to investigate cerebrospinal fluid (CSF) biomarker evidence of CNS infection, immune activation and neuronal injury in convalescent compared with acute infection. Method(s): We included 68 (35% female) patients >=18 years with CSF sampled during acute (46), 3-6 months after (22) SARS-CoV-2 infection or both (17), and 20 (70% female) healthy controls from longitudinal studies. The 22 patients sampled only at 3-6 months were recruited in a PASC protocol. CSF N-Ag was analyzed using an ultrasensitive antigen capture immunoassay platform (S-PLEX SARS-CoV-2 N Kit, Meso Scale Diagnostics, LLC. Rockville, MD). Additional analyses included CSF beta2-microglobulin (beta2M)], IFN-gamma, IL-6, TNF-alpha neurofilament light (NfL), and total and phosphorylated tau. Log-transformed CSF biomarkers were compared using ANOVA (Tukey post-hoc test). Result(s): Patients sampled during acute infection had moderate (27) or severe (19) COVID-19. In patients sampled at 3-6 months, corresponding initial severity was 10 (mild), 14 (moderate), and 15 (severe). At 3-6 months, 31/39 patients reported neurocognitive symptoms;8/17 patients also sampled during acute infection reported full recovery after 3-6 months. CSF biomarker results are shown in Figure 1. SARS-CoV-2 RNA was universally undetectable. N-Ag was detectable only during acute infection (32/35) but was undetectable in all follow up and control samples. Significantly higher CSF concentrations of beta2M (p< 0.0001), IFN-gamma (p=0.02), IL-6 (p< 0.0001) and NfL (p=0.04) were seen in acute compared to post-infection. Compared to controls, beta2M (p< .0001), IL-6 (p< 0.0001) and NfL (p=0.005) were significantly higher in acute infection. No biomarker differences were seen post-infection compared with controls. No differences were seen in CSF GFAp, t-tau or p-tau. Conclusion(s): We found no evidence of residual infection (RNA, N-Ag), inflammation (beta2M, IL-6, IFN-gamma, TNF-alpha), astrocyte activity (GFAp) or neuronal injury (NfL, tau) 3-6 months after initial COVID-19, while significantly higher concentrations of several markers were found during acute infection, suggesting that PASC may be a consequence of earlier injury rather than active CNS damage. CSF beta2M, IL-6, IFN-gamma and NfL were significantly lower after 3-6 months than during acute COVID-19 and not different from healthy controls. (Figure Presented).

Morphological, Cellular, and Molecular Basis of Brain Infection in COVID-19 Patients and Its Association to Psychiatric Symptoms

Background: Although increasing evidence confirms neuropsychiatric manifestations associated mainly with severe COVID-19 infection, long-term neuropsychiatric dysfunction (recently characterized as part of "long COVID-19" syndrome) has been frequently observed after mild infection. Method(s): We performed a broad translational investigation, employing brain imaging and cognitive tests in 81 living COVID-19 patients (mildly infected individuals) as well as flow cytometry, respirometry, microscopy, proteomics, and metabolomics in postmortem brain samples, and in preclinical in vitro and ex vivo models. Result(s): We observed orbitofrontal cortical atrophy, neurocognitive impairment, excessive fatigue and anxiety symptoms in living individuals. Postmortem brain tissue from 26 individuals who died of COVID-19 revealed histopathological signs of brain damage. Five individuals out of the 26 exhibited foci of SARS- CoV-2 infection and replication, particularly in astrocytes. Supporting the hypothesis of astrocyte infection, neural stem cell-derived human astrocytes in vitro are susceptible to SARS-CoV-2 infection through a non-canonical mechanism that involves spike-NRP1 interaction. SARS-CoV-2-infected astrocytes manifested changes in energy metabolism and in key proteins and metabolites used to fuel neurons, as well as in the biogenesis of neurotransmitters. Moreover, human astrocyte infection elicits a secretory phenotype that significantly reduces neuronal viability. Conclusion(s): Our data support the model in which COVID-19 alter cortical thickness, promoting psychiatric symptoms. In addition, SARS-CoV-2 is able to reach the brain, infects astrocytes, and consequently, leads to neuronal death or dysfunction. These deregulated processes could contribute to the structural and functional alterations seen in the brains of COVID-19 patients. Funding Source: Sao Paulo Research Foundation (FAPESP) Keywords: COVID-19, Anxiety, Astrocytes, Multi-omics, Brain Magnetic Resonance Imaging (MRI)Copyright © 2023

SARS-CoV-2 Infection of Human Neurons Is TMPRSS2 Independent, Requires Endosomal Cell Entry, and Can Be Blocked by Inhibitors of Host Phosphoinositol-5 Kinase.

2019 coronavirus disease (COVID-19) is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition to respiratory illness, COVID-19 patients exhibit neurological symptoms lasting from weeks to months (long COVID). It is unclear whether these neurological manifestations are due to an infection of brain cells. We found that a small fraction of human induced pluripotent stem cell (iPSC)-derived neurons, but not astrocytes, were naturally susceptible to SARS-CoV-2. Based on the inhibitory effect of blocking antibodies, the infection seemed to depend on the receptor angiotensin-converting enzyme 2 (ACE2), despite very low levels of its expression in neurons. The presence of double-stranded RNA in the cytoplasm (the hallmark of viral replication), abundant synthesis of viral late genes localized throughout infected cells, and an increase in the level of viral RNA in the culture medium (viral release) within the first 48 h of infection suggested that the infection was productive. Productive entry of SARS-CoV-2 requires the fusion of the viral and cellular membranes, which results in the delivery of the viral genome into the cytoplasm of the target cell. The fusion is triggered by proteolytic cleavage of the viral surface spike protein, which can occur at the plasma membrane or from endosomes or lysosomes. We found that SARS-CoV-2 infection of human neurons was insensitive to nafamostat and camostat, which inhibit cellular serine proteases, including transmembrane serine protease 2 (TMPRSS2). Inhibition of cathepsin L also did not significantly block infection. In contrast, the neuronal infection was blocked by apilimod, an inhibitor of phosphatidyl-inositol 5 kinase (PIK5K), which regulates early to late endosome maturation. IMPORTANCE COVID-19 is a disease caused by the coronavirus SARS-CoV-2. Millions of patients display neurological symptoms, including headache, impairment of memory, seizures, and encephalopathy, as well as anatomical abnormalities, such as changes in brain morphology. SARS-CoV-2 infection of the human brain has been documented, but it is unclear whether the observed neurological symptoms are linked to direct brain infection. The mechanism of virus entry into neurons has also not been characterized. Here, we investigated SARS-CoV-2 infection by using a human iPSC-derived neural cell model and found that a small fraction of cortical-like neurons was naturally susceptible to infection. The productive infection was ACE2 dependent and TMPRSS2 independent. We also found that the virus used the late endosomal and lysosomal pathway for cell entry and that the infection could be blocked by apilimod, an inhibitor of cellular PIK5K.

Effects of Various Mrna-Lnp Vaccine Doses on Neuroinflammation in Balb/C Mice

It has been proven that mRNA vaccines are highly effective against the COVID-19 outbreak, and low prevalence of side effects has been shown. However, there are still many gaps in our understanding of the biology and biosafety of nucleic acids as components of lipid nanoparticles (LNPs) most often used as a system for inctracellular delivery of mRNA-based vaccines. It is known that LNPs cause severe injection site inflammation, have broad biodistribution profiles, and are found in multiple tissues of the body, including the brain, after administration. The role of new medications with such pharmacokinetics in inflammation developing in inaccessible organs is poorly understood. The study was aimed to assess the effects of various doses of mRNA-LNP expressing the reporter protein (0, 5, 10, and 20 microg of mRNA encoding the firefly luciferase) on the expression of neuroinflammation markers (Tnfalpha, Il1beta, Gfap, Aif1) in the prefrontal cortex and hypothalamus of laboratory animals 4, 8, and 30 h after the intramuscular injection of LNP nanoemulsion. It was shown that mRNA-LNP vaccines in a dose of 10-20 microg of mRNA could enhance Aif1 expression in the hypothalamus 8 h after vaccination, however, no such differences were observed after 30 h. It was found that the Gfap, l11beta, Tnfalpha expression levels in the hypothalamus observed at different times in the experimental groups were different. According to the results, mRNA-LNPs administered by the parenteral route can stimulate temporary activation of microglia in certain time intervals in the dose-dependent and site specific manner.Copyright © 2022 Pirogov Russian National Research Medical University. All rights reserved.

34th Annual Meeting of the Japanese Society for Neuroimmunology (JSNI)

The proceedings contain 14 papers. The topics discussed include: MOG-positive anti-NMDA receptor encephalitis with no demyelinating lesions: two case reports;safety and tolerability of rozanolixizumab in the randomized phase 3 MycarinG study;Outcomes from RAISE: A randomized, phase 3 trial of zilucoplan in generalized myasthenia gravis;efficacy and safety of zilucoplan in myasthenia gravis: responder analysis from the randomized Phase 3 RAISE trial;distinct effects among calcium-binding proteins for microglia to produce chemokines associated with the clinical severity of ALS;astroglial connexin 43 is a novel therapeutic target for a chronic multiple sclerosis model;targeting lymphocytes in SPMS: Th cell populations as a biomarker to predict the efficacy of Siponimod;CSF lysophospholipids as a novel biomarker in relapsing-remitting multiple sclerosis;the immune response to SARS-COV-2 MRNA vaccines in siponimod-treated patients with secondary progressive multiple sclerosis;patient characteristics of siponimod-treated SPMS patients in Japan: interim results from post-marketing surveillance;and efficacy of ravulizumab across sex and age subgroups of patients with generalized myasthenia gravis: a post hoc analysis of the CHAMPION MG study.

Progressive multifocal leukoencephalopathy, neuroradiology-neuropathology

Introduction: Progressive multifocal leukoencepha-lopathy (PmL) is an unfavorable demyelinating disease of the CNS caused by reactivation of JC virus (JCV). JCV is a double-stranded DNA human polyomavirus predominatingly acquired in childhood. Blood samples taken from healthy persons indicate that 50-90% of adults have been exposed to this virus. JCV is an opportunistic pathogen, with PmL manifesting primarily in patients with immunodefciency or taking immunomodulatory treatments or with lymphoproliferative diseases. We report a patient who developed PmL shortly after diagnosis of follicular lymphomma. Case presentation: A 70-year-old-woman admitted to the neurological departament with hemiparesis, psy-chomotor slowing down, balance problems, dizziness and in depressed mood. the patient underwent aorto-femoral transplant 12 years ago and for 10 years was under constant observation of a hematologist due to enlarged lymph nodes. Five years ago, the patient had planoepithelial cell carcinoma removed. the patient also sufered from COViD-19 infection and sufered from depression. elevated leukocytosis and D dimers, were the only abnormal results obtained in laboratory tests. However, pulmonary embolism was excluded in Ct angio. Cytometry of blood showed follicular lymphoma. Radiological fndings: mRi and Ct scans showed multiple asymmetrical pathological areas of hyperin-tense signal in t2-dependent images, hypointense in t1-dependent ones and Ct-hypodense regions which extended continuously in control examinations. they were located in the white matter of multiple lobes of both brain hemispheres subcortically and periventric-ullary. the subcortical U-fbers were involed. they did not show contrast enhancement and mass efect. they showed peripheral ring and patchy difusion restriction particularly at their leading edge. in spite of the used steroid therapy the patient's health deteriorated rapidly. the patient died of symptoms of cardio-respiratory failure 1 month after admission to hospital. Neuropathological features: the neuropathological examination revealed numerous foci of demyelination in the white matter of the frontal lobe, the parietal lobe in the pons and in the cerebellum. myelin losses were accompanied by damage to oligodendrocytes and proliferation of macrophages. the nuclei of the damaged oligodendrocytes were enlarged and hyperchromatic, and some had a "ground-glass" appearance typical of viral infection. the astrocytes were bizarre with lobulat-ed, hiperchromatic or hypochromatic nuclei and damage of cytoplasmic procesesses (clasmatodendrosis). Conclusion(s): the triad of neuropathological injuries: destruction of oligodendrocytes with intranuclear viral inclusions ("ground-glass" appearance), multifocal demyelination and bizarre astrocytes allowed for the diagnosis of late form of classical progressive multifo-cal leukoencephalopathy (cPmL), despite the short time since diagnosis of follicular lymphoma, but with many years of enlargement of the lymph nodes.

The original strain of SARS-CoV-2, the Delta variant, and the Omicron variant infect microglia efficiently, in contrast to their inability to infect neurons: Analysis using 2D and 3D cultures.

COVID-19 causes neurological damage, systemic inflammation, and immune cell abnormalities. COVID-19-induced neurological impairment may be caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which directly infects cells of the central nervous system (CNS) and exerts toxic effects. Furthermore, SARS-CoV-2 mutations occur constantly, and it is not well understood how the infectivity of the virus to cells of the CNS changes as the virus mutates. Few studies have examined whether the infectivity of cells of CNS - neural stem/progenitor cells (NS/PCs), neurons, astrocytes, and microglia - varies among SARS-CoV-2 mutant strains. In this study, therefore, we investigated whether SARS-CoV-2 mutations increase infectivity to CNS cells, including microglia. Since it was essential to demonstrate the infectivity of the virus to CNS cells in vitro using human cells, we generated cortical neurons, astrocytes, and microglia from human induced pluripotent stem cells (hiPSCs). We added pseudotyped lentiviruses of SARS-CoV-2 to each type of cells, and then we examined their infectivity. We prepared three pseudotyped lentiviruses expressing the S protein of the original strain (the first SARS-CoV-2 discovered in the world), the Delta variant, and the Omicron variant on their envelopes and analyzed differences of their ability to infect CNS cells. We also generated brain organoids and investigated the infectivity of each virus. The viruses did not infect cortical neurons, astrocytes, or NS/PCs, but microglia were infected by the original, Delta, and Omicron pseudotyped viruses. In addition, DPP4 and CD147, potential core receptors of SARS-CoV-2, were highly expressed in the infected microglia, while DPP4 expression was deficient in cortical neurons, astrocytes, and NS/PCs. Our results suggest that DPP4, which is also a receptor for Middle East respiratory syndrome-coronavirus (MERS-CoV), may play an essential role in the CNS. Our study is applicable to the validation of the infectivity of viruses that cause various infectious diseases in CNS cells, which are difficult to sample from humans.

Astrocytes and the Psychiatric Sequelae of COVID-19: What We Learned from the Pandemic.

COVID-19, initially regarded as specific lung disease, exhibits an extremely broad spectrum of symptoms. Extrapulmonary manifestations of the disease also include important neuropsychiatric symptoms with atypical characteristics. Are these disturbances linked to stress accompanying every systemic infection, or are due to specific neurobiological changes associated with COVID-19? Evidence accumulated so far indicates that the pathophysiology of COVID-19 is characterized by systemic inflammation, hypoxia resulting from respiratory failure, and neuroinflammation (either due to viral neurotropism or in response to cytokine storm), all affecting the brain. It is reasonable to hypothesize that all these events may initiate or worsen psychiatric and cognitive disorders. Damage to the brain triggers a specific type of reactive response mounted by neuroglia cells, in particular by astrocytes which are the homeostatic cell par excellence. Astrocytes undergo complex morphological, biochemical, and functional remodeling aimed at mobilizing the regenerative potential of the central nervous system. If the brain is not directly damaged, resolution of systemic pathology usually results in restoration of the physiological homeostatic status of neuroglial cells. The completeness and dynamics of this process in pathological conditions remain largely unknown. In a subset of patients, glial cells could fail to recover after infection thus promoting the onset and progression of COVID-19-related neuropsychiatric diseases. There is evidence from post-mortem examinations of the brains of COVID-19 patients of alterations in both astrocytes and microglia. In conclusion, COVID-19 activates a huge reactive response of glial cells, that physiologically act as the main controller of the inflammatory, protective and regenerative events. However, in some patients the restoration of glial physiological state does not occur, thus compromising glial function and ultimately resulting in homeostatic failure underlying a set of specific neuropsychiatric symptoms related to COVID-19.

Neuron-specific Biomarkers Associated With Neurological Manifestations In COVID-19: An Evidence Mapping Systematic Review

Introduction. We aimed to map and synthesize the available evidence on neuron-specific biomarkers related to COVID-19. Methods. A systematic review and qualitative evidence mapping synthesis was performed (PROSPERO-CRD42021266995). Searches were conducted in PubMed and Scopus, and complemented by manual search (July 2021). We included observational studies of any design assessing neurological biomarkers in adult patients (>18 years;with or without neurological comorbidities) diagnosed with COVID-19. Methodological quality of nonrandomized studies (case-control, cohorts) was assessed using the Newcastle-Ottawa Scale. Results. Overall, 14 studies (n=485 patients) conducted in Sweden (n=4 articles, 28.5%), Germany (n=3;21.4%), USA (n=3;21.4%), Canada, France, Italy and Norway (n=1 study each) were included. The most reported neurological symptoms (n=13 studies, 92.8%) were headache, confusion, general weakness, loss of smell/taste, cognitive impairments and behavioral changes. Prevalent neurological conditions included encephalopathies, neuropathies, myopathies, and delirium;most critical cases presented cerebrovascular events (n=4 studies, 28.5%). Hypertension, diabetes, obesity, dyslipidemia, and chronic lung disease were the most reported comorbidities. Eight different neuron-specific biomarkers were found in primary studies: neurofilament-light chain - NfL (n=10 studies;71.4%), glial fibrillary acidic-protein - GFAp (n=5;35.7%), tau protein (n=5;35.7%), neurofilament-heavy chain - NfH, S100B protein, ubiquitin C-terminal hydrolase L1 - UCH-L1, neuronspecific enolase and beta protein-amyloid - Abeta (n=1 study each). These biomarkers were found both in cerebrospinal fluid and blood/ plasma samples even without an evident cytokine storm. In patients with COVID-19, NfL and GFAp can act as sensitive indicators of neuroaxonal and astrocytic damages, respectively. Increased levels of NfL were significantly associated with severe COVID-19, unconsciousness and longer stay in the intensive care unit (p<0.05). Studies had an overall poor to moderate methodological quality. Conclusions. We identified eight neuron-specific biomarkers that should be further studied as prognostic factors of COVID-19. These findings can also guide the development of targeted therapies against SARS-CoV-2. Additional well-designed clinical trials are needed to strengthen this evidence and help understand the mechanisms of neurological symptoms and sequelae after COVID-19 infection.

Nasal anti-CD3 monoclonal antibody (Foralumab) reduces PET microglial activation and blood inflammatory biomarkers in two patients with non-active secondary progressive MS

Introduction: There are no effective treatments for non-active secondary progressive MS (SPMS), which is mediated by compartmentalized CNS inflammation, including activated microglia. We found that fully human anti-CD3 intranasal monoclonal antibody (Foralumab) suppressed disease in a chronic EAE model by dampening microglia and astrocyte inflammation. Nasal Foralumab does not enter the bloodstream or brain. A dose-finding study of nasal Foralumab in controls dosed at 10ug, 50ug and 250ug for 5 days found the drug to be safe with immune effects seen at 50ug. COVID patients dosed with 100ug of nasal Foralumab for 10 days was well-tolerated and exhibited positive effects on blood markers and lung inflammation. Objective(s): To determine if nasal Foralumab has a therapeutic effect on patients with non-active SPMS. Method(s): Two patients were identified with non-active SPMS and sustained clinical progression, despite use of approved DMT. EA1 is a 61-year-old male diagnosed for over 20 years and EA2 is a 42-year-old male diagnosed for 8 years, both last treated with ocrelizumab for 3 years. Treatment occurs in 3-week cycles with intranasal Foralumab 50ug/day administered 3x/week for 2 weeks with 1 week rest. Each cycle, clinical and neurological assessments are repeated, and imaging is repeated every 3 months. Result(s): EA1 has completed 6 months and EA2 has completed 3 months of treatment. To date, there have been no adverse reactions, local irritation, or laboratory abnormalities, and symptom progression has subsided. EA1 is feeling more stable, subjectively, and has noted improvement in lower extremity strength. EDSS, pyramidal motor score and T25FW have stabilized or improved. SDMT and 9HPT were stable during treatment. Microglial activation as measured by [F-18]PBR06 PET scan was significantly reduced 3 months after the start of nasal Foralumab, and this reduction was sustained after 7-week washout and at 6 months. Serum protein measurements of cytokines showed reduction of IFN-gamma, IL-18, IL-1s and IL-6 levels (Olink assay). Cellular immune studies showed increase in CD8 naive cells and decrease in CD8 effector cells, and alteration in gene expression as measured by single cell RNA sequencing. EA2 3-month laboratory and imaging results are pending and will be presented. Conclusion(s): Nasal Foralumab in non-active SPMS patients treated for at least 3 months reduced microglial activation, decreased levels of proinflammatory cytokines, and had positive clinical effects.

Role of neuroinflammation mediated potential alterations in adult neurogenesis as a factor for neuropsychiatric symptoms in Post-Acute COVID-19 syndrome-A narrative review.

Persistence of symptoms beyond the initial 3 to 4 weeks after infection is defined as post-acute COVID-19 syndrome (PACS). A wide range of neuropsychiatric symptoms like anxiety, depression, post-traumatic stress disorder, sleep disorders and cognitive disturbances have been observed in PACS. The review was conducted based on PRISMA-S guidelines for literature search strategy for systematic reviews. A cytokine storm in COVID-19 may cause a breach in the blood brain barrier leading to cytokine and SARS-CoV-2 entry into the brain. This triggers an immune response in the brain by activating microglia, astrocytes, and other immune cells leading to neuroinflammation. Various inflammatory biomarkers like inflammatory cytokines, chemokines, acute phase proteins and adhesion molecules have been implicated in psychiatric disorders and play a major role in the precipitation of neuropsychiatric symptoms. Impaired adult neurogenesis has been linked with a variety of disorders like depression, anxiety, cognitive decline, and dementia. Persistence of neuroinflammation was observed in COVID-19 survivors 3 months after recovery. Chronic neuroinflammation alters adult neurogenesis with pro-inflammatory cytokines supressing anti-inflammatory cytokines and chemokines favouring adult neurogenesis. Based on the prevalence of neuropsychiatric symptoms/disorders in PACS, there is more possibility for a potential impairment in adult neurogenesis in COVID-19 survivors. This narrative review aims to discuss the various neuroinflammatory processes during PACS and its effect on adult neurogenesis.

SARS-CoV-2-Induced Amyloidgenesis: Not One, but Three Hypotheses for Cerebral COVID-19 Outcomes.

The main neuropathological feature of Alzheimer's disease (AD) is extracellular amyloid deposition in senile plaques, resulting from an imbalance between the production and clearance of amyloid beta peptides. Amyloid deposition is also found around cerebral blood vessels, termed cerebral amyloid angiopathy (CAA), in 90% of AD cases. Although the relationship between these two amyloid disorders is obvious, this does not make CAA a characteristic of AD, as 40% of the non-demented population presents this derangement. AD is predominantly sporadic; therefore, many factors contribute to its genesis. Herein, the starting point for discussion is the COVID-19 pandemic that we are experiencing and how SARS-CoV-2 may be able to, both directly and indirectly, contribute to CAA, with consequences for the outcome and extent of the disease. We highlight the role of astrocytes and endothelial cells in the process of amyloidgenesis, as well as the role of other amyloidgenic proteins, such as fibrinogen and serum amyloid A protein, in addition to the neuronal amyloid precursor protein. We discuss three independent hypotheses that complement each other to explain the cerebrovascular amyloidgenesis that may underlie long-term COVID-19 and new cases of dementia.

Retinas of human donors with COVID-19 disease show morphological alterations and signs of inflammation including glial activation

Purpose : Different signs of inflammation have been described in the brains of COVID-19 patients. In the retina, the fundus eye exam of these patients shows cotton wool spots, microhemorrhages, and a decrease in vascular density. However, morphological alterations of retinal cells in these patients are unknown. Thus, the aim was to analyze the morphological changes of the retinal cells from human donors with COVID-19 to establish several stages of response to damage in these cells and to define correlations with clinical parameters. Methods : The retinas of human donors with COVID-19 (n = 16) and control subjects (n = 12) obtained from the General University Hospital Consortium of Valencia were analyzed. Immunohistochemical stainings were performed on transversal sections or flat-mount retinas to study photoreceptors, microglial cells, Müller cells, astrocytes, and the presence of ACE2. TUNEL assays and confocal microscopy imaging were carried out. Correlations were calculated between retinal and clinical parameters. Results : Mean age of COVID-19 and control group were 80±10 and 70±8 years respectively. Müller cells, outer segment of cones and retinal pigment epithelium presented ACE2 staining. Larger staining of ACE2 and CRALBP was observed in cell bodies of Müller cells in COVID group. Disorganization of honeycomb-like pattern formed by Müller cells in the outer nuclear layer and disruption of external limiting membrane was found in the 81.3% of COVID patients. The 56.3% of COVID patients showed gliosis compared to controls (40%). COVID-19 retinas also presented epiretinal membranes and astrocytes protruding to vitreous humor. The 93.8% of COVID-19 patients had activated or ameboid-shape microglia. Microglial nodules around vessels and a reduction of the area occupied by microglia in these retinas were observed. COVID-19 group showed a more severe degeneration of cones. Cone degeneration correlated with Müller cell activation. Age of COVID patients correlated inversely with total retinal degeneration. Conclusions : Morphological alterations in the cone photoreceptors as well as glial activation showing an inflammatory state of the retina were observed in COVID-19 patients.

Dexamethasone: Therapeutic Applications, Targets and Translation

Dexamethasone is a synthetic corticosteroid that has historically been used to treat inflammation, such as from osteoarthritis, spinal cord injury and, more recently, COVID-19. The mechanism of action of dexamethasone is generally known to include attenuation of pro-inflammatory responses as well as upregulation of anti-inflammatory elements. A major issue with the use of dexamethasone is its delivery, as it is normally administered in large quantities via methods like bolus injection to attempt to maintain sufficient concentrations days or weeks after administration. In this review, we examine the mechanism of action of dexamethasone and its effects on three major cell types in the context of specific diseases: macrophages in the context of COVID, chondrocytes in the context of osteoarthritis, and astrocytes in the context of neuro-inflammatory disease. From this, we identify the key proinflammatory cytokines interleukin-1 (IL-1) and Tumor Necrosis Factor alpha (TNF-a) as universal effectors of inflammation that should be targeted alongside dexamethasone administration. Additionally, we review current extended release dosing mechanisms for dexamethasone to act over periods of weeks and months. We suggest that dual treatment of dexamethasone with IL-1 and/or TNF-a monoclonal antibodies will be an effective immediate treatment for inflammation, while the addition of fully developed dexamethasone extended release mechanisms will allow for effective long-term control of inflammatory disease. [ FROM AUTHOR] Copyright of Nano Life is the property of World Scientific Publishing Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

The SARS-CoV-2 envelope protein disrupts barrier function in an in vitro human blood-brain barrier model.

Patients with coronavirus disease 2019 (COVID-19) have been frequently reported to exhibit neurological manifestations and disruption of the blood-brain barrier (BBB). Among the risk factors for BBB breakdown, the loss of endothelial cells and pericytes has caused widespread concern. Recent studies have revealed that severe acute respiratory syndrome coronavirus 2 envelope (S2E) protein caused cell death. We tested the hypothesis that the S2E protein alone could induce BBB dysfunction. The S2E protein bound to human BBB-related cells and inhibited cell viability in a dose- and time-dependent manner. Importantly, the S2E protein disrupted barrier function in an in vitro BBB model composed of HCMEC/D3 (brain endothelial cell line), HBVP (brain vascular pericyte), and U87MG (astrocyte cell line) cells and suppressed the expression of major genes involved in maintaining endothelial permeability and function. In addition, the S2E protein crossed the HCMEC/D3 monolayer. The S2E protein triggered inflammatory responses in HCMEC/D3 and U87MG cells. Taken together, these results show for the first time that the S2E protein has a negative impact on the BBB. Therapies targeting the S2E protein could protect against and treat central nervous system manifestations in COVID-19 patients.

DJ-1-Nrf2 axis is activated upon murine ß-coronavirus infection in the CNS.

Coronaviruses have emerged as alarming pathogens owing to their inherent ability of genetic variation and cross-species transmission. Coronavirus infection burdens the endoplasmic reticulum (ER.), causes reactive oxygen species production and induces host stress responses, including unfolded protein response (UPR) and antioxidant system. In this study, we have employed a neurotropic murine ß-coronavirus (M-CoV) infection in the Central Nervous System (CNS) of experimental mice model to study the role of host stress responses mediated by interplay of DJ-1 and XBP1. DJ-1 is an antioxidant molecule with established functions in neurodegeneration. However, its regulation in virus-induced cellular stress response is less explored. Our study showed that M-CoV infection activated the glial cells and induced antioxidant and UPR genes during the acute stage when the viral titer peaks. As the virus particles decreased and acute neuroinflammation diminished at day ten p.i., a significant up-regulation in UPR responsive XBP1, antioxidant DJ-1, and downstream signaling molecules, including Nrf2, was recorded in the brain tissues. Additionally, preliminary in silico analysis of the binding between the DJ-1 promoter and a positively charged groove of XBP1 is also investigated, thus hinting at a mechanism behind the upregulation of DJ-1 during MHV-infection. The current study thus attempts to elucidate a novel interplay between the antioxidant system and UPR in the outcome of coronavirus infection.