Chemokine CXCL10 and Coronavirus-Induced Neurologic Disease

Recent Advances in Immunological Landscape and Immunotherapeutic Agent of Nipah Virus Infection

Over the last two decades, the Nipah virus (NiV) emerged as a highly lethal zoonotic pathogen to humans. Outbreaks occurred occasionally in South and Southeast Asia. Therefore, a safe and effective vaccine against the virus is needed to fight against the deadly virus. Understanding the immunological landscape during this lethal virus infection is necessary in this direction. However, we found scattered information on the immunological landscape of the virus's reservoir, as well as hosts such as humans and livestock. The review provides a recent understanding of the immunological landscape of the virus's reservoir, human hosts, monoclonal antibodies, and vaccines for NiV infection. To describe the immunological landscape, we divided our review article into some points. Firstly, we illustrated bats' immune response as a reservoir during the NiV infection. Secondly, we illustrated an overview of the molecular mechanisms underlying the immune response to the NiV infection, various immune cells, humans' innate immune response, adaptive immunity, and the landscape of cytokines and chemokines. We also discussed INF escape, NET evasion, the T cell landscape, and the B cell landscape during virus infection. Thirdly, we also demonstrated the potential monoclonal antibody therapeutics, and vaccines. Finally, neutralizing antibodies (nAbs) of NiV and potentially other therapeutic strategies were discussed. The review will help researchers for better understanding the immunological landscape, mAbs, and vaccines, enabling them to develop their next-generation versions.

AMG487 alleviates influenza A (H1N1) virus-induced pulmonary inflammation through decreasing IFN-γ-producing lymphocytes and IFN-γ concentrations

BACKGROUND AND PURPOSE

Severe influenza virus-infected patients have high systemic levels of Th1 cytokines (including IFN-γ). Intrapulmonary IFN-γ increases pulmonary IFN-γ-producing T lymphocytes through the CXCR3 pathway. Virus-infected mice lacking IP-10/CXCR3 demonstrate lower pulmonary neutrophilic inflammation. AMG487, an IP-10/CXCR3 antagonist, ameliorates virus-induced lung injury in vivo through decreasing viral loads. This study examined whether AMG487 could treat H1N1 virus-induced mouse illness through reducing viral loads or decreasing the number of lymphocytes or neutrophils.

EXPERIMENTAL APPROACH

Here, we studied the above-mentioned effects and underlying mechanisms in vivo.

KEY RESULTS

H1N1 virus infection caused bad overall condition and pulmonary inflammation characterized by the infiltration of lymphocytes and neutrophils. From Day-5 to Day-10 post-virus infection, bad overall condition, pulmonary lymphocytes, and IFN-γ concentrations increased, while pulmonary H1N1 viral titres and neutrophils decreased. Both anti-IFN-γ and AMG487 alleviated virus infection-induced bad overall condition and pulmonary lymphocytic inflammation. Pulmonary neutrophilic inflammation was mitigated by AMG487 on Day-5 post-infection, but was not mitigated by AMG487 on Day-10 post-infection. H1N1 virus induced increases of IFN-γ, IP-10, and IFN-γ-producing lymphocytes and activation of the Jak2-Stat1 pathways in mouse lungs, which were inhibited by AMG487. Anti-IFN-γ decreased IFN-γ and IFN-γ-producing lymphocytes on Day-5 post-infection. AMG487 but not anti-IFN-γ decreased viral titres in mouse lung homogenates or BALF. Higher virus load did not increase pulmonary inflammation and IFN-γ concentrations when mice were treated with AMG487.

CONCLUSION AND IMPLICATIONS

AMG487 may ameliorate H1N1 virus-induced pulmonary inflammation through decreasing IFN-γ-producing lymphocytes rather than reducing viral loads or neutrophils.

SARS-CoV-2 nucleocapsid protein, rather than spike protein, triggers a cytokine storm originating from lung epithelial cells in patients with COVID-19

PURPOSE

The aim of this study was to elucidate the factors associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that may initiate cytokine cascades and correlate the clinical characteristics of patients with coronavirus disease 2019 (COVID-19) with their serum cytokine profiles.

METHODS

Recombinant baculoviruses displaying SARS-CoV-2 spike or nucleocapsid protein were constructed and transfected into A549 cells and THP-1-derived macrophages, to determine which protein initiate cytokine release. SARS-CoV-2-specific antibody titers and cytokine profiles of patients with COVID-19 were determined, and the results were associated with their clinical characteristics, such as development of pneumonia or length of hospital stay.

RESULTS

The SARS-CoV-2 nucleocapsid protein, rather than the spike protein, triggers lung epithelial A549 cells to express IP-10, RANTES, IL-16, MIP-1α, basic FGF, eotaxin, IL-15, PDGF-BB, TRAIL, VEGF-A, and IL-5. Additionally, serum CTACK, basic FGF, GRO-α, IL-1α, IL-1RA, IL-2Rα, IL-9, IL-15, IL-16, IL-18, IP-10, M-CSF, MIF, MIG, RANTES, SCGF-β, SDF-1α, TNF-α, TNF-β, VEGF, PDGF-BB, TRAIL, β-NGF, eotaxin, GM-CSF, IFN-α2, INF-γ, and MCP-1 levels were considerably increased in patients with COVID-19. Among them, patients with pneumonia had higher serum IP-10 and M-CSF levels than patients without. Patients requiring less than 3 weeks to show negative COVID-19 tests after contracting COVID-19 had higher serum IP-10 levels than the remaining patients.

CONCLUSION

Our study revealed that nucleocapsid protein, lung epithelial cells, and IP-10 may be potential targets for the development of new strategies to prevent, or control, severe COVID-19.

Staphylococcus aureus acquires resistance to glycopeptide antibiotic vancomycin via CXCL10

BACKGROUND

Glycopeptide antibiotic vancomycin is a bactericidal antibiotic available for the infection to Staphylococcus aureus (SA), however, SA has a strong adaptive capacity and thereby acquires resistance to vancomycin. This study aims to illuminate the possible molecular mechanism of vancomycin resistance of SA based on the 16S rRNA sequencing data and microarray profiling data.

METHODS

16S rRNA sequencing data of control samples and urinary tract infection samples were retrieved from the EMBL-EBI (European Molecular Biology Laboratory - European Bioinformatics Institute) database. Correlation of gut flora and clinical indicators was evaluated. The possible targets regulated by SA were predicted by microarray profiling and subjected to KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis. CXCL10 gene knockout and overexpression were introduced to evaluate the effect of CXCL10 on the virulence of SA and the resistance to vancomycin. SA strains were co-cultured with urethral epithelial cells in vitro. The presence of SA virulence factors was detected using PCR. Biofilm formation of SA strains was assessed using the microtiter plate method. Furthermore, the antibiotic sensitivity of SA strains was evaluated through vancomycin testing.

RESULTS

Gut flora and its species abundance had significant difference between urinary tract infection and control samples. SA was significantly differentially expressed in urinary tract infection samples. Resistance of SA to vancomycin mainly linked to the D-alanine metabolism pathway. SA may participate in the occurrence of urinary tract infection by upregulating CXCL10. In addition, CXCL10 mainly affected the SA resistance to vancomycin through the TLR signaling pathway. In vitro experimental results further confirmed that the overexpression of CXCL10 in SA increased SA virulence and decreased its susceptibility to vancomycin. In vitro experimental validation demonstrated that the knockout of CXCL10 in urethral epithelial cells enhanced the sensitivity of Staphylococcus aureus (SA) to vancomycin.

CONCLUSION

SA upregulates the expression of CXCL10 in urethral epithelial cells, thereby activating the TLR signaling pathway and promoting resistance to glycopeptide antibiotics in SA.

Large-Scale Proteome Profiling Identifies Biomarkers Associated with Suspected Neurosyphilis Diagnosis

Neurosyphilis (NS) is a central nervous system (CNS) infection caused by Treponema pallidum (T. pallidum). NS can occur at any stage of syphilis and manifests as a broad spectrum of clinical symptoms. Often referred to as "the great imitator," NS can be easily overlooked or misdiagnosed due to the absence of standard diagnostic tests, potentially leading to severe and irreversible organ dysfunction. In this study, proteomic and machine learning model techniques are used to characterize 223 cerebrospinal fluid (CSF) samples to identify diagnostic markers of NS and provide insights into the underlying mechanisms of the associated inflammatory responses. Three biomarkers (SEMA7A, SERPINA3, and ITIH4) are validated as contributors to NS diagnosis through multicenter verification of an additional 115 CSF samples. We anticipate that the identified biomarkers will become effective tools for assisting in diagnosis of NS. Our insights into NS pathogenesis in brain tissue may inform therapeutic strategies and drug discoveries for NS patients.

The Impact of Innate Components on Viral Pathogenesis in the Neurotropic Coronavirus Encephalomyelitis Mouse Model

Recognition of viruses invading the central nervous system (CNS) by pattern recognition receptors (PRRs) is crucial to elicit early innate responses that stem dissemination. These innate responses comprise both type I interferon (IFN-I)-mediated defenses as well as signals recruiting leukocytes to control the infection. Focusing on insights from the neurotropic mouse CoV model, this review discusses how early IFN-I, fibroblast, and myeloid signals can influence protective anti-viral adaptive responses. Emphasis is placed on three main areas: the importance of coordinating the distinct capacities of resident CNS cells to induce and respond to IFN-I, the effects of select IFN-stimulated genes (ISGs) on host immune responses versus viral control, and the contribution of fibroblast activation and myeloid cells in aiding the access of T cells to the parenchyma. By unraveling how the dysregulation of early innate components influences adaptive immunity and viral control, this review illustrates the combined effort of resident CNS cells to achieve viral control.

Photobiomodulation reduces neuropathic pain after spinal cord injury by downregulating CXCL10 expression

BACKGROUND

Many studies have recently highlighted the role of photobiomodulation (PBM) in neuropathic pain (NP) relief after spinal cord injury (SCI), suggesting that it may be an effective way to relieve NP after SCI. However, the underlying mechanisms remain unclear. This study aimed to determine the potential mechanisms of PBM in NP relief after SCI.

METHODS

We performed systematic observations and investigated the mechanism of PBM intervention in NP in rats after SCI. Using transcriptome sequencing, we screened CXCL10 as a possible target molecule for PBM intervention and validated the results in rat tissues using reverse transcription-polymerase chain reaction and western blotting. Using immunofluorescence co-labeling, astrocytes and microglia were identified as the cells responsible for CXCL10 expression. The involvement of the NF-κB pathway in CXCL10 expression was verified using inhibitor pyrrolidine dithiocarbamate (PDTC) and agonist phorbol-12-myristate-13-acetate (PMA), which were further validated by an in vivo injection experiment.

RESULTS

Here, we demonstrated that PBM therapy led to an improvement in NP relative behaviors post-SCI, inhibited the activation of microglia and astrocytes, and decreased the expression level of CXCL10 in glial cells, which was accompanied by mediation of the NF-κB signaling pathway. Photobiomodulation inhibit the activation of the NF-κB pathway and reduce downstream CXCL10 expression. The NF-κB pathway inhibitor PDTC had the same effect as PBM on improving pain in animals with SCI, and the NF-κB pathway promoter PMA could reverse the beneficial effect of PBM.

CONCLUSIONS

Our results provide new insights into the mechanisms by which PBM alleviates NP after SCI. We demonstrated that PBM significantly inhibited the activation of microglia and astrocytes and decreased the expression level of CXCL10. These effects appear to be related to the NF-κB signaling pathway. Taken together, our study provides evidence that PBM could be a potentially effective therapy for NP after SCI, CXCL10 and NF-kB signaling pathways might be critical factors in pain relief mediated by PBM after SCI.

COVID-19 and the impact on Alzheimer's disease pathology

Coronavirus disease 2019 (COVID-19) has rapidly escalated into a global pandemic that primarily affects older and immunocompromised individuals due to underlying clinical conditions and suppressed immune responses. Furthermore, COVID-19 patients exhibit a spectrum of neurological symptoms, indicating that COVID-19 can affect the brain in a variety of manners. Many studies, past and recent, suggest a connection between viral infections and an increased risk of neurodegeneration, raising concerns about the neurological effects of COVID-19 and the possibility that it may contribute to Alzheimer's disease (AD) onset or worsen already existing AD pathology through inflammatory processes given that both COVID-19 and AD share pathological features and risk factors. This leads us to question whether COVID-19 is a risk factor for AD and how these two conditions might influence each other. Considering the extensive reach of the COVID-19 pandemic and the devastating impact of the ongoing AD pandemic, their combined effects could have significant public health consequences worldwide.

Intrapulmonary IFN-γ instillation causes chronic lymphocytic inflammation in the spleen and lung through the CXCR3 pathway

Some patients with chronic refractory cough have high levels of pulmonary IFN-γ and IFN-γ-producing T lymphocytes. Pulmonary IFN-γ administration causes acute airway lymphocytic inflammation and cough hypersensitivity by increasing the number of pulmonary IFN-γ-producing T lymphocytes, but these lymphocytes may be recruited from other organs. Intraperitoneal IFN-γ injection can increase the spleen weight of mice. It remains elusive whether pulmonary IFN-γ can induce chronic airway lymphocytic inflammation and cough hypersensitivity by stimulating the proliferation of IFN-γ -producing T lymphocytes in the spleen. Here, we found that pulmonary IFN-γ administration induced chronic airway inflammation and chronic cough hypersensitivity with an increased number of IFN-γ-producing T lymphocytes in the spleen, blood and lung. Pulmonary IFN-γ administration also increased 1) the proliferation of spleen lymphocytes in vivo and 2) the IP-10 level and CXCR3+ T lymphocyte numbers in the spleen and lung of mice. IP-10 could promote the proliferation of spleen lymphocytes in vitro but not blood lymphocytes or lung-resident lymphocytes. AMG487, a potent inhibitor of binding between IP-10 and CXCR3, could block pulmonary IFN-γ instillation-induced chronic airway lymphocytic inflammation and the proliferation of IFN-γ-producing T lymphocytes in mouse spleens. In conclusion, intrapulmonary IFN-γ instillation may induce the proliferation of splenic IFN-γ-producing T lymphocytes through IP-10 and the CXCR3 pathway. The IFN-γ-producing T lymphocytes in blood, partly released from the mouse spleen, may be partly attracted to the lung by pulmonary IP-10 through the CXCR3 pathway. IFN-γ-producing T lymphocytes and IFN-γ in the lung may cause chronic airway lymphocytic inflammation and chronic cough hypersensitivity.

Probable Neuropsychological and Cognitive Complications Due to Cytokine Storm in Patients With COVID-19

Introduction

COVID-19 (coronavirus disease 2019) was first identified in China in December 2019 and is rapidly spreading worldwide as a pandemic. Since COVID-19 causes mild to severe acute respiratory syndrome, most studies in this context have focused on pathogenesis primarily in the respiratory system. However, evidence shows that the central nervous system (CNS) may also be affected by COVID-19. Since COVID-19 is spreading, it is necessary to study its possible cognitive effects on COVID-19 patients and their recovery.

Methods

The articles used in this study were searched by keywords, such as cytokine storm and COVID-19, COVID-19 and executive dysfunction, cognitive disorder, and COVID-19, central nervous system (CNS) and COVID-19, coronavirus, neuroinvasion in Science Direct, Scopus, PubMed, Embase, and Web of Science databases based on preferred reporting items for systematic reviews and meta-analysis (PRISMA) checklist. The study evaluates all observational studies published between December 2019 and April 2021 in peer-reviewed journals, including cross-sectional, cohort, case-control studies, case reports, and case series. The search result was 106 articles, of which 73 articles related to COVID-19, the stages of infection by this virus, its effect on the nervous system and neurological symptoms, the cytokine storm caused by this infection, and the possible cognitive consequences caused by this virus in patients, has been reviewed. Other articles were not checked due to their limited relevance to the topic under discussion.

Results

Studies showed that neurons may be directly affected by severe acute respiratory syndrome coronavirus (SARS-CoV)-1 and SARS-CoV-2. Furthermore, various studies indicated that systemic inflammation (so-called "cytokine storm") is also responsible for brain damage induced by infection with SARS-CoV-1 and SARS-CoV-2. In such a way that these patients showed elevated levels of interleukin (IL-), 6, 8, and 10 and of tumor necrosis factor-alpha (TNF-α) in their blood.

Conclusion

Various cognitive defects have been observed following an increased level of cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6, 8. Therefore, due to the increased level of these pro-inflammatory factors in the brains of these patients, cognitive deficits can be expected, which need further investigation.

Liang-Ge-San: a classic traditional Chinese medicine formula, attenuates acute inflammation via targeting GSK3β

Sepsis is a serious life-threatening health disorder with high morbidity and mortality rates that burden the world, but there is still a lack of more effective and reliable drug treatment. Liang-Ge-San (LGS) has been shown to have anti-inflammatory effects and is a promising candidate for the treatment of sepsis. However, the anti-sepsis mechanism of LGS has still not been elucidated. In this study, a set of genes related to inflammatory chemotaxis pathways was downloaded from Encyclopedia of Genes and Genomes (KEGG) and integrated with sepsis patient information from the Gene Expression Omnibus (GEO) database to perform differential gene expression analysis. Glycogen synthase kinase-3β (GSK-3β) was found to be the feature gene after these important genes were examined using the three algorithms Random Forest, support vector machine recursive feature elimination (SVM-REF), and least absolute shrinkage and selection operator (LASSO), and then intersected with possible treatment targets of LGS found through the search. Upon evaluation, the receiver operating characteristic (ROC) curve of GSK-3β indicated an important role in the pathogenesis of sepsis. Immune cell infiltration analysis suggested that GSK-3β expression was associated with a variety of immune cells, including neutrophils and monocytes. Next, lipopolysaccharide (LPS)-induced zebrafish inflammation model and macrophage inflammation model was used to validate the mechanism of LGS. We found that LGS could protect zebrafish against a lethal challenge with LPS by down-regulating GSK-3β mRNA expression in a dose-dependent manner, as indicated by a decreased neutrophils infiltration and reduction of inflammatory damage. The upregulated mRNA expression of GSK-3β in LPS-induced stimulated RAW 264.7 cells also showed the same tendency of depression by LGS. Critically, LGS could induce M1 macrophage polarization to M2 through promoting GSK-3β inactivation of phosphorylation. Taken together, we initially showed that anti-septic effects of LGS is related to the inhibition on GSK-3β, both in vitro and in vivo.

Brain transcriptomics reveal the activation of neuroinflammation pathways during acute Orientia tsutsugamushi infection in mice

Scrub typhus, an acute febrile illness caused by Orientia tsutsugamushi (Ot), is prevalent in endemic areas with one million new cases annually. Clinical observations suggest central nervous system (CNS) involvement in severe scrub typhus cases. Acute encephalitis syndrome (AES) associated with Ot infection is a major public health problem; however, the underlying mechanisms of neurological disorder remain poorly understood. By using a well-established murine model of severe scrub typhus and brain RNA-seq, we studied the brain transcriptome dynamics and identified the activated neuroinflammation pathways. Our data indicated a strong enrichment of several immune signaling and inflammation-related pathways at the onset of disease and prior to host death. The strongest upregulation of expression included genes involved in interferon (IFN) responses, defense response to bacteria, immunoglobulin-mediated immunity, IL-6/JAK-STAT signaling, and TNF signaling via NF-κB. We also found a significant increase in the expression of core genes related to blood-brain barrier (BBB) disruption and dysregulation in severe Ot infection. Brain tissue immunostaining and in vitro infection of microglia revealed microglial activation and proinflammatory cytokine production, suggesting a crucial role of microglia in neuroinflammation during scrub typhus. This study provides new insights into neuroinflammation in scrub typhus, highlighting the impact of excessive IFN responses, microglial activation, and BBB dysregulation on disease pathogenesis.

Altered cytokine levels in the cerebrospinal fluid of adult patients with autism spectrum disorder

BACKGROUND

Despite intensive research, the etiological causes of autism spectrum disorder (ASD) remain elusive. Immunological mechanisms have recently been studied more frequently in the context of maternal autoantibodies and infections, as well as altered cytokine profiles. For the detection of immunological processes in the central nervous system, analyses of cerebrospinal fluid (CSF) are advantageous due to its proximity to the brain. However, cytokine studies in the CSF of ASD patients are sparse.

METHODS

CSF was collected from a patient sample of 24 adults (m = 16, f = 8, age: 30.3 ± 11.6 years) with ASD and compared to a previously published mentally healthy control sample of 39 neurological patients with idiopathic intracranial hypertension. A magnetic bead multiplexing immunoassay was used to measure multiple cytokines in CSF.

RESULTS

Significantly decreased interferon-γ-induced protein-10 (p = 0.001) and monocyte chemoattractant protein-1 (p = 0.041) levels as well as significantly higher interleukin-8 levels (p = 0.041) were detected in patients with ASD compared with the control group.

CONCLUSION

The main finding of this study is an altered cytokine profile in adult patients with ASD compared to the control group. This may indicate immune dysregulation in a subgroup of adult ASD patients. Further studies in larger cohorts that examine a broader spectrum of chemokines and cytokines in general are needed to detect possible specific immune signatures in ASD.

Cell-based experimental strategies for myelin repair in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS), diagnosed at a mean age of 32 years. CNS glia are crucial players in the onset of MS, primarily involving astrocytes and microglia that can cause/allow massive oligodendroglial cells death, without immune cell infiltration. Current therapeutic approaches are aimed at modulating inflammatory reactions during relapsing episodes, but lack the ability to induce very significant repair mechanisms. In this review article, different experimental approaches based mainly on the application of different cell types as therapeutic strategies applied for the induction of myelin repair and/or the amelioration of the disease are discussed. Regarding this issue, different cell sources were applied in various experimental models of MS, with different results, both in significant improvements in remyelination and the reduction of neuroinflammation and glial activation, or in neuroprotection. All cell types tested have advantages and disadvantages, which makes it difficult to choose a better option for therapeutic application in MS. New strategies combining cell-based treatment with other applications would result in further improvements and would be good candidates for MS cell therapy and myelin repair.

CXCL10 Chemokine: A Critical Player in RNA and DNA Viral Infections

Chemokines constitute a group of small, secreted proteins that regulate leukocyte migration and contribute to their activation. Chemokines are crucial inflammatory mediators that play a key role in managing viral infections, during which the profile of chemokine expression helps shape the immune response and regulate viral clearance, improving clinical outcome. In particular, the chemokine ligand CXCL10 and its receptor CXCR3 were explored in a plethora of RNA and DNA viral infections. In this review, we highlight the expression profile and role of the CXCL10/CXCR3 axis in the host defense against a variety of RNA and DNA viral infections. We also discuss the interactions among viruses and host cells that trigger CXCL10 expression, as well as the signaling cascades induced in CXCR3 positive cells.

Pulmonary IFN-γ Causes Lymphocytic Inflammation and Cough Hypersensitivity by Increasing the Number of IFN-γ-Secreting T Lymphocytes

PURPOSE

Respiratory viral infection increases the number of lung-resident T lymphocytes, which enhance cough sensitivity by producing interferon-γ (IFN-γ). It is poorly understood why IFN-γ-secreting T lymphocytes persist for a long time when the respiratory viruses have been removed.

METHODS

Repeated pulmonary administration of IFN-γ and intraperitoneal injection with different inhibitors were used to study the effects of pulmonary IFN-γ in mice and guinea pigs.

RESULTS

IFN-γ administration caused the increasing of IFN-γ-secreting T lymphocytes in both lung and blood, followed by the elevated physiological level of IFN-γ in the lung, the airway inflammation and the airway epithelial damage. IFN-γ administration also enhanced the cough sensitivity of guinea pigs. IFN-γ activated the STAT1 and extracellular signal-regulated kinase (ERK) pathways in lung tissues, released IFN-γ-inducible protein 10 (IP-10), and resulted in F-actin accumulation in lung-resident lymphocytes. The CXC chemokine receptor 3 (CXCR3) inhibitor potently suppressed all the IFN-γ-induced inflammatory changes. The STAT1 inhibitor mitigated IFN-γ-secreting T lymphocytes infiltration by inhibiting T lymphocytes proliferation. F-actin accumulation and the ERK1/2 pathway contributed to pulmonary IFN-γ-induced augmentation of the airway inflammation and increasing of IFN-γ-secreting T lymphocytes in blood.

CONCLUSIONS

High physiological levels of IFN-γ in the lung may cause pulmonary lymphocytic inflammation and cough hypersensitivity by increasing the number of IFN-γ-secreting T lymphocytes through the IP-10 and CXCR3 pathways.

EGR1 Upregulation during Encephalitic Viral Infections Contributes to Inflammation and Cell Death

Early growth response 1 (EGR1) is an immediate early gene and transcription factor previously found to be significantly upregulated in human astrocytoma cells infected with Venezuelan equine encephalitis virus (VEEV). The loss of EGR1 resulted in decreased cell death but had no significant impact on viral replication. Here, we extend these studies to determine the impacts of EGR1 on gene expression following viral infection. Inflammatory genes CXCL3, CXCL8, CXCL10, TNF, and PTGS2 were upregulated in VEEV-infected cells, which was partially dependent on EGR1. Additionally, transcription factors, including EGR1 itself, as well as ATF3, FOS, JUN, KLF4, EGR2, and EGR4 were found to be partially transcriptionally dependent on EGR1. We also examined the role of EGR1 and the changes in gene expression in response to infection with other alphaviruses, including eastern equine encephalitis virus (EEEV), Sindbis virus (SINV), and chikungunya virus (CHIKV), as well as Zika virus (ZIKV) and Rift Valley fever virus (RVFV), members of the Flaviviridae and Phenuiviridae families, respectively. EGR1 was significantly upregulated to varying degrees in EEEV-, CHIKV-, RVFV-, SINV-, and ZIKV-infected astrocytoma cells. Genes that were identified as being partially transcriptionally dependent on EGR1 in infected cells included ATF3 (EEEV, CHIKV, ZIKV), JUN (EEEV), KLF4 (SINV, ZIKV, RVFV), CXCL3 (EEEV, CHIKV, ZIKV), CXCL8 (EEEV, CHIKV, ZIKV, RVFV), CXCL10 (EEEV, RVFV), TNF-α (EEEV, ZIKV, RVFV), and PTGS2 (EEEV, CHIKV, ZIKV). Additionally, inhibition of the inflammatory gene PTGS2 with Celecoxib, a small molecule inhibitor, rescued astrocytoma cells from VEEV-induced cell death but had no impact on viral titers. Collectively, these results suggest that EGR1 induction following viral infection stimulates multiple inflammatory mediators. Managing inflammation and cell death in response to viral infection is of utmost importance, especially during VEEV infection where survivors are at-risk for neurological sequalae.

IP-10 and complement activation as friend or foe in COVID-19

Introduction

The Innate immune system senses danger signals of COVID-19 infection and produce an orchestration of cellular, complement and cytokines cascades. These led to the approach using immunosuppressive agents. It is intriguing whether certain biomarkers can aid the proper administration of such drugs.

Methods

Plasma specimens of 58 COVID-19 patients with differing severity, from very mild illness (group A), mild (group B), moderate (group C), and severe/critical illness (group D) were assayed for cyto-chemokines and terminal complement complex (SC5b-9) during the course of diseases. None received anti-IL-6 therapy, there was no mortality in this cohort.

Results

IP-10 and RANTES levels were dominant cytokines. IP-10 levels increased significantly in all groups when compared between pre-nadir and nadir phases (group A, p =0.428; group B =0.034; group C =0.159; group D <0.001) and in groups B and D when compared between nadir and recovery phases ( p <0.001). RANTES levels were elevated in all groups across all phases with no significant differences. SC5b-9 levels increased significantly as compared to healthy controls [pre-nadir- group A versus healthy, p =0.122; group B-D versus healthy, p =0.021); nadir-group A versus healthy, p =0.003; group B-D versus healthy, p <0.001; recovery phase ( p <0.001)] but not between groups A and B-D at pre-nadir ( p=0.606).

Conclusion

The absence of significant pro-inflammatory responses and early elevation of IP-10 levels and complement activation may be favorable and necessary for viral elimination in COVID-19 patients. Expression of distinct cyto-chemokines during each clinical phase may be useful for guiding proper therapeutic interventions on alleviating thrombo-inflammation responses to COVID-19 infection.

The roles of Eph receptors, neuropilin-1, P2X7, and CD147 in COVID-19-associated neurodegenerative diseases: inflammasome and JaK inhibitors as potential promising therapies

The novel coronavirus disease 2019 (COVID-19) pandemic has spread worldwide, and finding a safe therapeutic strategy and effective vaccine is critical to overcoming severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Therefore, elucidation of pathogenesis mechanisms, especially entry routes of SARS-CoV-2 may help propose antiviral drugs and novel vaccines. Several receptors have been demonstrated for the interaction of spike (S) protein of SARS-CoV-2 with host cells, including angiotensin-converting enzyme (ACE2), ephrin ligands and Eph receptors, neuropilin 1 (NRP-1), P2X7, and CD147. The expression of these entry receptors in the central nervous system (CNS) may make the CNS prone to SARS-CoV-2 invasion, leading to neurodegenerative diseases. The present review provides potential pathological mechanisms of SARS-CoV-2 infection in the CNS, including entry receptors and cytokines involved in neuroinflammatory conditions. Moreover, it explains several neurodegenerative disorders associated with COVID-19. Finally, we suggest inflammasome and JaK inhibitors as potential therapeutic strategies for neurodegenerative diseases.

Neopterin and CXCL-10 in Cerebrospinal Fluid as Potential Biomarkers of Neuroinvasive Dengue and Chikungunya

Dengue (DENV) and chikungunya viruses (CHIKV) cause severe neurological complications, sometimes undiagnosed. Therefore, the use of more accessible neuroinflammatory biomarkers can be advantageous considering their diagnostic and prognostic potential for aggravated clinical outcomes. In this study, we aimed to evaluate neopterin and C-X-C motif chemokine ligand 10 (CXCL-10) in cerebrospinal fluid (CSF) for the diagnosis of neuroinvasive DENV and CHIKV. We analyzed the CSF of 66 patients with neurological disorders, comprising 12 neuroinvasive DENV/CHIKV, 20 inflammatory control (viral, bacterial, and fungal meningitis, and autoimmune disorders), and 24 noninflammatory control (cerebrovascular disease, dementia, neoplasm). There was no difference between the concentration of CSF neopterin in the neuroinvasive DENV/CHIKV and control groups. However, there was a significant difference in the CXCL-10 level when comparing the neuroinvasive DENV/CHIKV group and the non-inflammatory control (p < 0.05). Furthermore, we found a linear correlation between neopterin and CXCL-10 CSF levels in the three groups. For the DENV/CHIKV neuroinvasive diagnosis, the ROC curve showed the best cut-off values for CSF neopterin at 11.23 nmol/L (sensitivity of 67% and specificity of 63%), and for CSF CXCL-10 at 156.5 pg/mL (91.7% sensitivity and specificity). These results show that CXCL-10 in CSF represents an accurate neuroinflammatory biomarker that may contribute to neuroinvasive DENV/CHIKV diagnosis.

Neuroinflammation: A Signature or a Cause of Epilepsy?

Epilepsy can be both a primary pathology and a secondary effect of many neurological conditions. Many papers show that neuroinflammation is a product of epilepsy, and that in pathological conditions characterized by neuroinflammation, there is a higher probability to develop epilepsy. However, the bidirectional mechanism of the reciprocal interaction between epilepsy and neuroinflammation remains to be fully understood. Here, we attempt to explore and discuss the relationship between epilepsy and inflammation in some paradigmatic neurological and systemic disorders associated with epilepsy. In particular, we have chosen one representative form of epilepsy for each one of its actual known etiologies. A better understanding of the mechanistic link between neuroinflammation and epilepsy would be important to improve subject-based therapies, both for prophylaxis and for the treatment of epilepsy.

Potential neurotoxic activity of diverse molecules released by microglia

Microglia are the professional immune cells of the brain, which support numerous physiological processes. One of the defensive functions provided by microglia involves secretion of cytotoxins aimed at destroying invading pathogens. It is also recognized that the adverse activation of microglia in diseased brains may lead to secretion of cytotoxic molecules, which could be damaging to the surrounding cells, including neurons. Several of these toxins, such as reactive oxygen and nitrogen species, L-glutamate, and quinolinic acid, are widely recognized and well-studied. This review is focused on a structurally diverse group of less-established microglia neurotoxins, which were selected by applying the two criteria that these molecules 1) can be released by microglia, and 2) have the potential to be directly harmful to neurons. The following 11 molecules are discussed in detail: amyloid beta peptides (Aβ); cathepsin (Cat)B and CatD; C-X-C motif chemokine ligand (CXCL)10 and CXCL12 (5-67); high mobility group box (HMGB)1; lymphotoxin (LT)-α; matrix metalloproteinase (MMP)-2 and MMP-9; platelet-activating factor (PAF); and prolyl endopeptidase (PEP). Molecular mechanisms of their release by microglia and neurotoxicity, as well as available evidence implicating their involvement in human neuropathologies are summarized. Further studies on several of the above molecules are warranted to confirm either their microglial origin in the brain or direct neurotoxic effects. In addition, investigations into the differential secretion patterns of neurotoxins by microglia in response to diverse stimuli are required. This research could identify novel therapeutic targets for neurological disorders involving adverse microglial activation.

Persistent SARS-2 infections contribute to long COVID-19

COVID-19 is a serious disease that has infected more than 40 million people. Beside significant mortality, the SARS-CoV-2 infection causes considerable and sustained morbidity, dubbed long COVID. This paper argues that some of this morbidity may be due to a persistent systemic infection. Persistent infection is indicated by continued virus RNA shedding. The virus’ superantigen could overstimulate anti-virus immune responses, and thereby induce negative feedback loops, that paradoxically allow the virus to persist. The superantigen would induce strong immune response to any residual infection. This hypothesis suggests that clearing the virus infection completely would be an appropriate intervention against long COVID.

Role of Melatonin on Virus-Induced Neuropathogenesis-A Concomitant Therapeutic Strategy to Understand SARS-CoV-2 Infection

Viral infections may cause neurological disorders by directly inducing oxidative stress and interrupting immune system function, both of which contribute to neuronal death. Several reports have described the neurological manifestations in Covid-19 patients where, in severe cases of the infection, brain inflammation and encephalitis are common. Recently, extensive research-based studies have revealed and acknowledged the clinical and preventive roles of melatonin in some viral diseases. Melatonin has been shown to have antiviral properties against several viral infections which are accompanied by neurological symptoms. The beneficial properties of melatonin relate to its properties as a potent antioxidant, anti-inflammatory, and immunoregulatory molecule and its neuroprotective effects. In this review, what is known about the therapeutic role of melatonin in virus-induced neuropathogenesis is summarized and discussed.

Does coronaviruses induce neurodegenerative diseases? A systematic review on the neurotropism and neuroinvasion of SARS-CoV-2

The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in 2019 in Wuhan, China. Clinically, respiratory tract symptoms as well as other organs disorders are observed in patients positively diagnosed coronavirus disease 2019 (COVID-19). In addition, neurological symptoms, mainly anosmia, ageusia and headache were observed in many patients. Once in the central nervous system (CNS), the SARS-CoV-2 can reside either in a quiescent latent state, or eventually in actively state leading to severe acute encephalitis, characterized by neuroinflammation and prolonged neuroimmune activation. SRAS-CoV-2 requires angiotensin-converting enzyme 2 (ACE2) as a cell entry receptor. The expression of this receptor in endothelial cells of blood-brain barrier (BBB) shows that SRAS-CoV-2 may have higher neuroinvasive potential compared to known coronaviruses. This review summarizes available information regarding the impact of SRAS-CoV-2 in the brain and tended to identify its potential pathways of neuroinvasion. We offer also an understanding of the long-term impact of latently form of SARS-CoV-2 on the development of neurodegenerative disorders. As a conclusion, the persistent infection of SRAS-CoV-2 in the brain could be involved on human neurodegenerative diseases that evolve a gradual process, perhapes, over several decades.

Pathology of Coronavirus Infections: A Review of Lesions in Animals in the One-Health Perspective

Coronaviruses (CoVs) are worldwide distributed RNA-viruses affecting several species, including humans, and causing a broad spectrum of diseases. Historically, they have not been considered a severe threat to public health until two outbreaks of COVs-related atypical human pneumonia derived from animal hosts appeared in 2002 and in 2012. The concern related to CoVs infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild animals is also most likely. In light of this CoV zoonotic risk, and their ability to adapt to new species and dramatically spread, it appears pivotal to understand the pathophysiology and mechanisms of tissue injury of known CoVs within the "One-Health" concept. This review specifically describes all CoVs diseases in animals, schematically representing the tissue damage and summarizing the major lesions in an attempt to compare and put them in relation, also with human infections. Some information on pathogenesis and genetic diversity is also included. Investigating the lesions and distribution of CoVs can be crucial to understand and monitor the evolution of these viruses as well as of other pathogens and to further deepen the pathogenesis and transmission of this disease to help public health preventive measures and therapies.

Environmental Nanoparticles, SARS-CoV-2 Brain Involvement, and Potential Acceleration of Alzheimer's and Parkinson's Diseases in Young Urbanites Exposed to Air Pollution

Alzheimer's and Parkinson's diseases (AD, PD) have a pediatric and young adult onset in Metropolitan Mexico City (MMC). The SARS-CoV-2 neurotropic RNA virus is triggering neurological complications and deep concern regarding acceleration of neuroinflammatory and neurodegenerative processes already in progress. This review, based on our MMC experience, will discuss two major issues: 1) why residents chronically exposed to air pollution are likely to be more susceptible to SARS-CoV-2 systemic and brain effects and 2) why young people with AD and PD already in progress will accelerate neurodegenerative processes. Secondary mental consequences of social distancing and isolation, fear, financial insecurity, violence, poor health support, and lack of understanding of the complex crisis are expected in MMC residents infected or free of SARS-CoV-2. MMC residents with pre-SARS-CoV-2 accumulation of misfolded proteins diagnostic of AD and PD and metal-rich, magnetic nanoparticles damaging key neural organelles are an ideal host for neurotropic SARS-CoV-2 RNA virus invading the body through the same portals damaged by nanoparticles: nasal olfactory epithelium, the gastrointestinal tract, and the alveolar-capillary portal. We urgently need MMC multicenter retrospective-prospective neurological and psychiatric population follow-up and intervention strategies in place in case of acceleration of neurodegenerative processes, increased risk of suicide, and mental disease worsening. Identification of vulnerable populations and continuous effort to lower air pollution ought to be critical steps.

Emerging Neurological and Psychobiological Aspects of COVID-19 Infection

The SARS-CoV-2 virus, first reported in December 2019 in China, is the causative agent of the current COVID-19 pandemic that, at the time of writing (1 November 2020) has infected almost 43 million people and caused the death of more than 1 million people. The spectrum of clinical manifestations observed during COVID-19 infection varies from asymptomatic to critical life-threatening clinical conditions. Emerging evidence shows that COVID-19 affects far more organs than just the respiratory system, including the heart, kidneys, blood vessels, liver, as well as the central nervous system (CNS) and the peripheral nervous system (PNS). It is also becoming clear that the neurological and psychological disturbances that occur during the acute phase of the infection may persist well beyond the recovery. The aim of this review is to propel further this emerging and relevant field of research related to the pathophysiology of neurological manifestation of COVID-19 infection (Neuro-COVID). We will summarize the PNS and CNS symptoms experienced by people with COVID-19 both during infection and in the recovery phase. Diagnostic and pharmacological findings in this field of study are strongly warranted to address the neurological and psychological symptoms of COVID-19.

Coronavirus Infection of the Central Nervous System: Animal Models in the Time of COVID-19

Naturally occurring coronaviral infections have been studied for several decades in the context of companion and production animals, and central nervous system involvement is a common finding, particularly in cats with feline infectious peritonitis (FIP). These companion and production animal coronaviruses have many similarities to recent human pandemic-associated coronaviruses such as SARS-CoV, MERS-CoV, and SARS-CoV2 (COVID-19). Neurological involvement is being increasingly recognized as an important clinical presentation in human COVID-19 patients, often associated with para-infectious processes, and potentially with direct infection within the CNS. Recent breakthroughs in the treatment of coronaviral infections in cats, including neurological FIP, have utilized antiviral drugs similar to those currently in human COVID-19 clinical trials. Differences in specific coronavirus and host factors are reflected in major variations in incidence and mechanisms of CNS coronaviral infection and pathology between species; however, broad lessons relating to treatment of coronavirus infection present within the CNS may be informative across species.

Neurological Components in Coronavirus Induced Disease: A Review of the Literature Related to SARS, MERS, and COVID-19

Background. COVID-19 has been declared the pandemic of the 21st century, causing more than 45,000 deaths worldwide. The abrupt release of SARS-CoV-2 demonstrated the potential infection, morbidity, and lethality of zoonotic viruses and human-to-human transmission. Fever, cough, and fatigue are reported as the most common symptoms of the disease, including acute respiratory distress syndrome, and also signs of severe illness, such as shock, acute cardiac injury, and renal lesions, are described. Considering the previous works related to human coronavirus and other zoonotic infections, it has been demonstrated that the neuroinvasive propensity is a common characteristic of coronaviruses, especially in SARS-CoV and MERS-CoV. Objective. In the present review, we analyzed the potential neurological components involved in coronavirus infections and detailed the neurological syndromes related to COVID-19. We also examined the mechanism of transmission and CNS pathology related to other viruses with similar structures such as SARS-CoV and MERS-CoV. Methods. A comprehensive search of different original articles and clinical, experimental, and review studies was conducted in MEDLINE/PubMed, Scopus, and Web of Science. We selected 92 articles that have been published in journals or preprints according to the search words and the inclusion and exclusion criteria. Results. COVID-19 patients may experience neurological symptoms such as headache, impaired mental status, confusion, dizziness, nausea and vomiting, anosmia/hyposmia, and dysgeusia/hypogeusia as initial symptoms, with more severe manifestations such as seizures or coma later on. The neurological signs shown are clinical symptoms similar to those reported for SARS-CoV and MERS-CoV. Given that both SARS-CoV and MERS-CoV have similar structures, these viruses may share comparable neurological symptoms and similar progression. Coronaviruses are linked to central nervous system dysfunction, and they are also reported as the probable cause of multiple sclerosis, encephalitis, and meningitis.

Role of cytotoxic T lymphocytes and interferon-γ in coronavirus infection: Lessons from murine coronavirus infections in mice

Murine coronavirus (CoV) is a beta-CoV that infects mice by binding to carcinoembryonic antigen-related cell adhesion molecule 1. Intraperitoneal infection with the murine CoV strain JHM (JHMV) induces acute mild hepatitis in mice. While both innate and acquired immune responses play a significant role in the protection against murine CoV infection in mice, CD8⁺ cytotoxic T lymphocytes (CTLs) and interferon-γ are essential for viral clearance in JHMV-induced hepatitis. In addition, CoVs are characterized by high diversity, caused by mutations, recombination, and gene gain/loss. 25V16G is an immune-escape JHMV variant, which lacks a dominant CTL epitope. By evading immune responses, 25V16G establishes persistent infections, leading to granulomatous serositis in interferon-γ-deficient mice. These examples of CoV-associated pathogenesis in mice might provide useful information on other CoV infections, including coronavirus disease 2019 (COVID-19).

Drug targets for COVID-19 therapeutics: Ongoing global efforts

The current global pandemic COVID-19 caused by the SARS-CoV-2 virus has already inflicted insurmountable damage both to the human lives and global economy. There is an immediate need for identification of effective drugs to contain the disastrous virus outbreak. Global efforts are already underway at a war footing to identify the best drug combination to address the disease. In this review, an attempt has been made to understand the SARS-CoV-2 life cycle, and based on this information potential druggable targets against SARS-CoV-2 are summarized. Also, the strategies for ongoing and future drug discovery against the SARS-CoV-2 virus are outlined. Given the urgency to find a definitive cure, ongoing drug repurposing efforts being carried out by various organizations are also described. The unprecedented crisis requires extraordinary efforts from the scientific community to effectively address the issue and prevent further loss of human lives and health.

Neuropathogenic human coronaviruses: A review

Human Coronaviruses (HCoVs) have long been known as respiratory viruses. However, there are reports of neurological findings in HCoV infections, particularly in patients infected with the novel severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) amid Coronavirus disease 2019 (COVID‐19) pandemic. Therefore, it is essential to interpret the interaction of HCoVs and the nervous system and apply this understanding to the COVID‐19 pandemic. This review of the literature analyses how HCoVs, in general, and SARS‐CoV‐2, in particular, affect the nervous system, highlights the various underlying mechanisms, addresses the associated neurological and psychiatric manifestations, and identifies the neurological risk factors involved. This review of literature shows the magnitude of neurological conditions associated with HCoV infections, including SARS‐CoV‐2. This review emphasises, that, during HCoV outbreaks, such as COVID‐19, a focus on early detection of neurotropism, alertness for the resulting neurological complications, and the recognition of neurological risk factors are crucial to reduce the workload on hospitals, particularly intensive‐care units and neurological departments.

COVID-19 Pulmonary and Olfactory Dysfunctions: Is the Chemokine CXCL10 the Common Denominator?

COVID-19 is an ongoing viral pandemic that emerged from East Asia and quickly spread to the rest of the world. SARS-CoV-2 is the virus causing COVID-19. Acute respiratory distress syndrome (ARDS) is definitely one of the main clinically relevant consequences in patients with COVID-19. Starting from the earliest reports of the COVID-19 pandemic, two peculiar neurological manifestations (namely, hyposmia/anosmia and dysgeusia) were reported in a relevant proportion of patients infected by SARS-CoV-2. At present, the physiopathologic mechanisms accounting for the onset of these symptoms are not yet clarified. CXCL10 is a pro-inflammatory chemokine with a well-established role in the COVID-19-related cytokine storm and in subsequent development of ARDS. CXCL10 is also known to be involved in coronavirus-induced demyelination. On these bases, a role for CXCL10 as the common denominator between pulmonary and olfactory dysfunctions could be envisaged. The aim of the present report will be to hypothesize a role for CXCL10 in COVID-19 olfactory dysfunctions. Previous evidences supporting our hypothesis, with special emphasis to the role of CXCL10 in coronavirus-induced demyelination, the anatomical and physiological peculiarity of the olfactory system, and the available data supporting their link during COVID-19 infections, will be overviewed.

Update on T cells in the virally infected brain: friends and foes

PURPOSE OF REVIEW

The present review will outline neuroprotective and neurotoxic effects of central nervous system (CNS) infiltrating T cells during viral infections. Evidence demonstrating differential roles for antiviral effector and resident memory T-cell subsets in virologic control and immunopathology in the CNS will be discussed. Potential therapeutic targets emanating from a growing understanding of T-cell-initiated neuropathology that impacts learning and memory will also be delineated.

RECENT FINDINGS

The critical role for T cells in preventing and clearing CNS infections became incontrovertible during the era of acquired immunodeficiency syndrome. Recent studies have further defined differential roles of T-cell subsets, including resident memory T cells (Trm), in antiviral immunity and, unexpectedly, in postinfectious cognitive dysfunction. Mechanisms of T-cell-mediated effects include differential innate immune signaling within neural cells that are virus-specific.

SUMMARY

T-cell cytokines that are essential for cell-mediated virologic control during neurotropic viral infections have recently been identified as potential targets to prevent post-infection memory disorders. Further identification of T-cell subsets, their antigen specificity, and postinfection localization of Trm will enhance the efficacy of immunotherapies through minimization of immunopathology.

How to detect and track chronic neurologic sequelae of COVID-19? Use of auditory brainstem responses and neuroimaging for long-term patient follow-up

This review intends to provide an overview of the current knowledge on neurologic sequelae of COVID-19 and their possible etiology, and, based on available data, proposes possible improvements in current medical care procedures. We conducted a thorough review of the scientific literature on neurologic manifestations of COVID-19, the neuroinvasive propensity of known coronaviruses (CoV) and their possible effects on brain structural and functional integrity. It appears that around one third of COVID-19 patients admitted to intensive care units (ICU) for respiratory difficulties exhibit neurologic symptoms. This may be due to progressive brain damage and dysfunction triggered by severe hypoxia and hypoxemia, heightened inflammation and SARS-CoV-2 dissemination into brain parenchyma, as suggested by current reports and analyses of previous CoV outbreaks. Viral invasion of the brain may particularly target and alter brainstem and thalamic functions and, consequently, result in sensorimotor dysfunctions and psychiatric disorders. Moreover, data collected from other structurally homologous CoV suggest that SARS-CoV-2 infection may lead to brain cell degeneration and demyelination similar to multiple sclerosis (MS). Hence, current evidence warrants further evaluation and long-term follow-up of possible neurologic sequelae in COVID-19 patients. It may be particularly relevant to evaluate brainstem integrity in recovered patients, as it is suspected that this cerebral area may particularly be dysfunctional following SARS-CoV-2 infection. Because CoV infection can potentially lead to chronic neuroinflammation and progressive demyelination, neuroimaging features and signs of MS may also be evaluated in the long term in recovered COVID-19 patients.

In vitro analysis of the renin-angiotensin system and inflammatory gene transcripts in human bronchial epithelial cells after infection with severe acute respiratory syndrome coronavirus

INTRODUCTION

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a recently identified coronavirus family member that triggers a respiratory disease similar to severe acute respiratory syndrome coronavirus (SARS-CoV). SARS-CoV and SARS-CoV-2 are very similar to each other in many respects, such as structure, genetics, and pathobiology. We hypothesized that coronaviruses could affect pulmonary tissues via integration with the critical immune genes after their interaction with renin-angiotensin system (RAS) elements. The aim of the present bioinformatics study was to assess expression changes of the RAS and non-RAS genes, particularly immune response genes, in the lung epithelial cells after infection with SARS-CoV.

METHODS

Linear regression, hierarchical clustering, pathway analysis, and network analysis were performed using the E-GEOD-17400 data set.

RESULTS

The whole-genome expression data of the lung epithelial cells infected with SARS-CoV for 12, 24, and 48 hours were analyzed, and a total of 15 RAS family and 29 immune genes were found to be highly correlated with the exposure time to the virus in the studied groups.

CONCLUSION

RAS genes are important at the initiation of the infections caused by coronavirus family members and may have a strong relationship with the exchange of immune genes in due course following the infection.

C-X-C Motif Chemokine 10 Contributes to the Development of Neuropathic Pain by Increasing the Permeability of the Blood-Spinal Cord Barrier

Neuropathic pain is among the most debilitating forms of chronic pain. Studies have suggested that chronic pain pathogenesis involves neuroimmune interactions and blood-spinal cord barrier (BSCB) disruption. However, the underlying mechanisms are poorly understood. We modeled neuropathic pain in rats by inducing chronic constriction injury (CCI) of the sciatic nerve and analyzed the effects on C-X-C motif chemokine 10 (CXCL10)/CXCR3 activation, BSCB permeability, and immune cell migration from the circulation into the spinal cord. We detected CXCR3 expression in spinal neurons and observed that CCI induced CXCL10/CXCR3 activation, BSCB disruption, and mechanical hyperalgesia. CCI-induced BSCB disruption enabled circulating T cells to migrate into the spinal parenchyma. Intrathecal administration of an anti-CXCL10 antibody not only attenuated CCI-induced hyperalgesia, but also reduced BSCB permeability, suggesting that CXCL10 acts as a key regulator of BSCB integrity. Moreover, T cell migration may play a critical role in the neuroimmune interactions involved in the pathogenesis of CCI-induced neuropathic pain. Our results highlight CXCL10 as a new potential drug target for the treatment of nerve injury-induced neuropathic pain.

Involvement of the Nervous System in SARS-CoV-2 Infection

As a severe and highly contagious infectious disease, coronavirus disease 2019 (COVID-19) has caused a global pandemic. Several case reports have demonstrated that the respiratory system is the main target in patients with COVID-19, but the disease is not limited to the respiratory system. Case analysis indicated that the nervous system can be invaded by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and that 36.4% of COVID-19 patients had neurological symptoms. Importantly, the involvement of the CNS may be associated with poor prognosis and disease worsening. Here, we discussed the symptoms and evidence of nervous system involvement (directly and indirectly) caused by SARS-CoV-2 infection and possible mechanisms. CNS symptoms could be a potential indicator of poor prognosis; therefore, the prevention and treatment of CNS symptoms are also crucial for the recovery of COVID-19 patients.

Disrupted CXCR2 Signaling in Oligodendroglia Lineage Cells Enhances Myelin Repair in a Viral Model of Multiple Sclerosis

CXCR2 is a chemokine receptor expressed on oligodendroglia that has been implicated in the pathogenesis of neuroinflammatory demyelinating diseases as well as enhancement of the migration, proliferation, and myelin production by oligodendroglia. Using an inducible proteolipid protein (Plp) promoter-driven Cre-loxP recombination system, we were able to assess how timed ablation of Cxcr2 in oligodendroglia affected disease following intracranial infection with the neurotropic JHM strain of mouse hepatitis virus (JHMV). Generation of Plp-Cre-ER(T)::Cxcr2flox/flox transgenic mice (termed Cxcr2-CKO mice) allows for Cxcr2 to be silenced in oligodendrocytes in adult mice following treatment with tamoxifen. Ablation of oligodendroglia Cxcr2 did not influence clinical severity in response to intracranial infection with JHMV. Infiltration of activated T cells or myeloid cells into the central nervous system (CNS) was not affected, nor was the ability to control viral infection. In addition, the severity of demyelination was similar between tamoxifen-treated mice and vehicle-treated controls. Notably, deletion of Cxcr2 resulted in increased remyelination, as assessed by g-ratio (the ratio of the inner axonal diameter to the total outer fiber diameter) calculation, compared to that in vehicle-treated control mice. Collectively, our findings argue that CXCR2 signaling in oligodendroglia is dispensable with regard to contributing to neuroinflammation, but its deletion enhances remyelination in a preclinical model of the human demyelinating disease multiple sclerosis (MS).IMPORTANCE Signaling through the chemokine receptor CXCR2 in oligodendroglia is important for developmental myelination in rodents, while chemical inhibition or nonspecific genetic deletion of CXCR2 appears to augment myelin repair in animal models of the human demyelinating disease multiple sclerosis (MS). To better understand the biology of CXCR2 signaling on oligodendroglia, we generated transgenic mice in which Cxcr2 is selectively ablated in oligodendroglia upon treatment with tamoxifen. Using a viral model of neuroinflammation and demyelination, we demonstrate that genetic silencing of CXCR2 on oligodendroglia did not affect clinical disease, neuroinflammation, or demyelination, yet there was increased remyelination. These findings support and extend previous findings suggesting that targeting CXCR2 may offer a therapeutic avenue for enhancing remyelination in patients with demyelinating diseases.