Respiratory syncytial virus activates epidermal growth factor receptor to suppress interferon regulatory factor 1-dependent interferon-lambda and antiviral defense in airway epithelium

Infection of nonclassic monocytes by respiratory syncytial virus induces an imbalance in the CD4+ T-cell subset response

Respiratory syncytial virus (RSV) causes lower respiratory tract infections in infants and young children, leading to a pathogenesis-associated imbalance in CD4+ T-cell subsets and monocyte subsets. To investigate whether RSV affects the imbalance of CD4+ T-cells through monocytes, we examined the effects of the RSV-infected monocyte subset on CD4+ T-cell subsets, namely, Th1, Th2, Th17, and regulatory T (Treg) subsets, on proliferation in vitro and identified key monocyte-derived cytokines. We found that RSV efficiently infects CD16+ monocytes, but not CD16- monocytes, via cocultures of CD4+ T-cells with RSV-infected CD16+ monocytes, inhibits Treg cell proliferation and increases Th2 cell frequency, suggesting that RSV causes an imbalance in the CD4+ T-cell subset by primarily infecting CD16+ monocytes. Our data also revealed that IL-1β and IL-10 are key cytokines responsible for the activities of RSV-infected CD16+ monocytes. In a mouse model, we found that high-efficiency RSV infection of mouse Ly6C- monocytes, corresponding to CD16+ monocytes in humans, and adoptive transfer of Ly6C- monocytes during RSV infection decreased the Treg frequency in the lungs and aggravated pneumonia. Our data indicate that RSV can increase its pathogenesis through infection of nonclassic monocytes, leading to a CD4+ T-cell imbalance.IMPORTANCEThis study identified a pathogenesis pathway related to the RSV-nonclassic monocyte-IL-1β/IL-10-CD4+ T-cell subset balance, which links the heterogeneity of monocytes to RSV pathogenesis and elucidates a new mechanism by which RSV infection disrupts the balance of CD4+ T cells during RSV infection. These new findings provide potential therapeutic targets for RSV infection.

Landscape of respiratory syncytial virus

ABSTRACT

Respiratory syncytial virus (RSV) is an enveloped, negative-sense, single-stranded RNA virus of the Orthopneumovirus  genus of the Pneumoviridae family in the order Mononegavirales. RSV can cause acute upper and lower respiratory tract infections, sometimes with extrapulmonary complications. The disease burden of RSV infection is enormous, mainly affecting infants and older adults aged 75 years or above. Currently, treatment options for RSV are largely supportive. Prevention strategies remain a critical focus, with efforts centered on vaccine development and the use of prophylactic monoclonal antibodies. To date, three RSV vaccines have been approved for active immunization among individuals aged 60 years and above. For children who are not eligible for these vaccines, passive immunization is recommended. A newly approved prophylactic monoclonal antibody, Nirsevimab, which offers enhanced neutralizing activity and an extended half-life, provides exceptional protection for high-risk infants and young children. This review provides a comprehensive and detailed exploration of RSV's virology, immunology, pathogenesis, epidemiology, clinical manifestations, treatment options, and prevention strategies.

Probenecid Inhibits Extracellular Signal-Regulated Kinase and c-Jun N-Terminal Kinase Mitogen-Activated Protein Kinase Pathways in Regulating Respiratory Syncytial Virus Response

We examined the effect of probenecid in regulating the ERK and JNK downstream MAPK pathways affecting respiratory syncytial virus replication.

BACKGROUND

We have previously shown that probenecid inhibits RSV, influenza virus, and SARS-CoV-2 replication in vitro in preclinical animal models and in humans. In a Phase two randomized, placebo-controlled, single-blind, dose range-finding study using probenecid to treat non-hospitalized patients with symptomatic, mild-to-moderate COVID-19, we previously showed that a 1000 mg twice daily treatment for 5 days reduced the median time to viral clearance from 11 to 7 days, and a 500 mg twice daily treatment for 5 days reduced the time to viral clearance from 11 to 9 days more than the placebo.

METHODS

In this study, we sought to determine the mechanism of action of the probenecid inhibition of RSV replication in human respiratory epithelial (A549) cells.

RESULTS

We show that probenecid inhibits the RSV-induced phosphorylation of JNKs and ERKs and the downstream phosphorylation of c-jun, a component of the AP-1 transcription complex needed for virus replication. The inhibition of JNKs by probenecid reversed the repression of transcription factor HNF-4.

CONCLUSION

The probenecid inhibition of JNK and ERK phosphorylation involves the MAPK pathway that precludes virus replication.

Network pharmacology, molecular docking, and untargeted metabolomics reveal molecular mechanisms of multi-targets effects of Qingfei Tongluo Plaster improving respiratory syncytial virus pneumonia

Objective

Qingfei Tongluo Plaster (QFP), an improved Chinese medicine hospital preparation, is an attractive treatment option due to its well clinical efficacy, convenience, economy, and patient compliance in the treatment of respiratory syncytial virus (RSV) pneumonia. The aim of this study was to investigate the efficacy mechanism of QFP on RSV rats from the perspective of alleviating lung inflammation and further explore the changes of serum metabolites and metabolic pathways in RSV rats under the influence of QFP.

Methods

This study used network pharmacological methods and molecular docking combined with molecular biology and metabolomics from multi-dimensional perspectives to screen and verify the therapeutic targets. Open online databases were used to speculate the gene targets of efficient ingredients and diseases. Then, we used the String database to examine the fundamental interaction of common targets of drugs and diseases. An online enrichment analysis was performed to predict the functional pathways. Molecular docking was applied to discover the binding modes between essential ingredients and crucial gene targets. Finally, we demonstrated the anti-inflammatory ability of QFP in the RSV-evoked pneumonia rat model and explained the mechanism in combination with the metabolomics results.

Results

There were 19 critical targets defined as the core targets: tumor necrosis factor (TNF), inducible nitric oxide synthase 2 (NOS2), mitogen-activated protein kinase 14 (MAPK14), g1/S-specific cyclin-D1 (CCND1), signal transducer and activator of transcription 1-alpha/beta (STAT1), proto-oncogene tyrosine-protein kinase Src (SRC), cellular tumor antigen p53 (TP53), interleukin-6 (IL6), hypoxia-inducible factor 1-alpha (HIF1A), RAC-alpha serine/threonine-protein kinase (AKT1), signal transducer and activator of transcription 3 (STAT3), heat shock protein HSP 90-alpha (HSP90AA1), tyrosine-protein kinase JAK2 (JAK2), cyclin-dependent kinase inhibitor 1 (CDKN1A), mitogen-activated protein kinase 3 (MAPK3), epidermal growth factor receptor (EGFR), myc proto-oncogene protein (MYC), protein c-Fos (FOS) and transcription factor p65 (RELA). QFP treated RSV pneumonia mainly through the phosphatidylinositol 3-kinase (PI3K)/RAC AKT pathway, HIF-1 pathway, IL-17 pathway, TNF pathway, and MAPK pathway. Animal experiments proved that QFP could effectively ameliorate RSV-induced pulmonary inflammation. A total of 28 metabolites underwent significant changes in the QFP treatment, and there are four metabolic pathways consistent with the KEGG pathway analyzed by network pharmacology, suggesting that they may be critical processes related to treatment.

Conclusion

These results provide essential perspicacity into the mechanisms of action of QFP as a promising anti-RSV drug.

Inflammatory response to SARS-CoV 2 and other respiratory viruses

INTRODUCTION

Lower respiratory tract infections (LRTI) remain a significant global cause of mortality and disability. Viruses constitute a substantial proportion of LRTI cases, with their pandemic potential posing a latent threat. After the SARS-CoV-2 pandemic, the resurgence of other respiratory viruses, including Influenza and Respiratory Syncytial Virus responsible for LRTI has been observed especially in susceptible populations.

AREAS COVERED

This review details the inflammatory mechanisms associated with three primary respiratory viruses: SARS-CoV-2, Influenza, and Respiratory Syncytial Virus (RSV). The focus will be on elucidating the activation of inflammatory pathways, understanding cellular contributions to inflammation, exploring the role of interferon and induced cell death in the response to these pathogens and detailing viral evasion mechanisms. Furthermore, the distinctive characteristics of each virus will be explained.

EXPERT OPINION

The study of viral pneumonia, notably concerning SARS-CoV-2, Influenza, and RSV, offers critical insights into infectious and inflammatory mechanisms with wide-ranging implications. Addressing current limitations, such as diagnostic accuracy and understanding host-virus interactions, requires collaborative efforts and investment in technology. Future research holds promise for uncovering novel therapeutic targets, exploring host microbiome roles, and addressing long-term sequelae. Integrating advances in molecular biology and technology will shape the evolving landscape of viral pneumonia research, potentially enhancing global public health outcomes.

IFN-λ drives distinct lung immune landscape changes and antiviral responses in human metapneumovirus infection

Human metapneumovirus (HMPV) is a primary cause of acute respiratory infection, yet there are no approved vaccines or antiviral therapies for HMPV. Early host responses to HMPV are poorly characterized, and further understanding could identify important antiviral pathways. Type III interferon (IFN-λ) displays potent antiviral activity against respiratory viruses and is being investigated for therapeutic use. However, its role in HMPV infection remains largely unknown. Here, we show that IFN-λ is highly upregulated during HMPV infection in vitro in human and mouse airway epithelial cells and in vivo in mice. We found through several immunological and molecular assays that type II alveolar cells are the primary producers of IFN-λ. Using mouse models, we show that IFN-λ limits lung HMPV replication and restricts virus spread from upper to lower airways but does not contribute to clinical disease. Moreover, we show that IFN-λ signaling is predominantly mediated by CD45- non-immune cells. Mice lacking IFN-λ signaling showed diminished loss of ciliated epithelial cells and decreased recruitment of lung macrophages in early HMPV infection along with higher inflammatory cytokine and interferon-stimulated gene expression, suggesting that IFN-λ may maintain immunomodulatory responses. Administration of IFN-λ for prophylaxis or post-infection treatment in mice reduced viral load without inflammation-driven weight loss or clinical disease. These data offer clinical promise for IFN-λ in HMPV treatment.

IMPORTANCE

Human metapneumovirus (HMPV) is a common respiratory pathogen and often contributes to severe disease, particularly in children, immunocompromised people, and the elderly. There are currently no licensed HMPV antiviral treatments or vaccines. Here, we report novel roles of host factor IFN-λ in HMPV disease that highlight therapeutic potential. We show that IFN-λ promotes lung antiviral responses by restricting lung HMPV replication and spread from upper to lower airways but does so without inducing lung immunopathology. Our data uncover recruitment of lung macrophages, regulation of ciliated epithelial cells, and modulation of inflammatory cytokines and interferon-stimulated genes as likely contributors. Moreover, we found these roles to be distinct and non-redundant, as they are not observed with knockout of, or treatment with, type I IFN. These data elucidate unique antiviral functions of IFN-λ and suggest IFN-λ augmentation as a promising therapeutic for treating HMPV disease and promoting effective vaccine responses.

Design, synthesis, biological assessment and molecular modeling studies of novel imidazothiazole-thiazolidinone hybrids as potential anticancer and anti-inflammatory agents

A new series of imidazothiazole derivatives bearing thiazolidinone moiety (4a-g and 5a-d) were designed, synthesized and evaluated for potential epidermal growth factor receptor (EGFR) kinase inhibition, anticancer and anti-inflammatory activity, cardiomyopathy toxicity and hepatotoxicity. Compound 4c inhibited EGFR kinase at a concentration of 18.35 ± 1.25 µM, whereas standard drug erlotinib showed IC50 value of 06.12 ± 0.92 µM. The molecular docking, dynamics simulation and MM-GBSA binding energy calculations revealed strong interaction of compound 4c with binding site of EGFR. The synthesized compounds were evaluated for their anticancer activity by MTT assay against three human cancer cell lines A549 (Lung), MCF-7 (Breast), HCT116 (Colon), one normal human embryonic kidney cell line HEK293 and also for their EGFR kinase inhibitory activity. Few compounds of the series (4a, 4b, 4c) showed promising growth inhibition against all the tested cancer cell lines and against EGFR kinase. Among these, compound 4c was found to be most active and displayed IC50 value of 10.74 ± 0.40, 18.73 ± 0.88 against cancer cell lines A549 and MCF7 respectively whereas it showed an IC50 value of 96.38 ± 1.79 against HEK293 cell line indicating lesser cytotoxicity for healthy cell. Compounds 4a, 4b and 4c were also examined for their apoptosis inducing potential through AO/EB dual staining assay and it was observed that their antiproliferative activity against A549 cells is mediated via induction of apoptosis. Cardiomyopathy studies showed normal cardiomyocytes with no marked sign of pyknotic nucleus of compounds 4b and 4c. Hepatotoxicity studies of compounds 4b and 4c also showed normal architecture of hepatocytes. Compounds 4a-g and 5a-d were also evaluated for their in-vitro anti-inflammatory activity by protein albumin denaturation assay. Among the tested compounds 4a-d and 5a-b showed promising activity and were selected for in-vivo inflammatory activity against carrageenan rat paw edema test. Among these compounds, 4b was found to be most active in the series showing 84.94% inhibition, whereas the standard drug diclofenac sodium showed 84.57% inhibition. Compound 4b also showed low ulcerogenic potential and lipid peroxidation. Thus, compounds 4c and 4b could be a promising lead compounds for developing anticancer and anti-inflammatory agents with low toxicity and selectivity.

Identification of epidermal growth factor receptor-tyrosine kinase inhibitor targeting the VP1 pocket of human rhinovirus

Screening a library of 1,200 preselected kinase inhibitors for anti-human rhinovirus 2 (HRV-2) activity in HeLa cells identified a class of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) as effective virus blockers. These were based on the 4-anilinoquinazoline-7-oxypiperidine scaffold, with the most potent representative AZ5385 inhibiting the virus with EC50 of 0.35 µM. Several structurally related analogs confirmed activity in the low µM range, while interestingly, other TKIs targeting EGFR lacked anti-HRV-2 activity. To further probe this lack of association between antiviral activity and EGFR inhibition, we stained infected cells with antibodies specific for activated EGFR (Y1068) and did not observe a dependency on EGFR-TK activity. Instead, consecutive passages of HRV-2 in HeLa cells in the presence of a compound and subsequent nucleotide sequence analysis of resistant viral variants identified the S181T and T210A alterations in the major capsid VP1 protein, with both residues located in the vicinity of a known hydrophobic pocket on the viral capsid. Further characterization of the antiviral effects of AZ5385 showed a modest virus-inactivating (virucidal) activity, while anti-HRV-2 activity was still evident when the inhibitor was added as late as 10 h post infection. The RNA copy/infectivity ratio of HRV-2 propagated in AZ5385 presence was substantially higher than that of control HRV indicating that the compound preferentially targeted HRV progeny virions during their maturation in infected cells. Besides HRV, the compound showed anti-respiratory syncytial virus activity, which warrants its further studies as a candidate compound against viral respiratory infections.

Interferon lambda in respiratory viral infection: immunomodulatory functions and antiviral effects in epithelium

Type III interferon (IFN-λ), a new member of the IFN family, was initially considered to possess antiviral functions similar to those of type I interferon, both of which are induced via the JAK/STAT pathway. Nevertheless, recent findings demonstrated that IFN-λ exerts a nonredundant antiviral function at the mucosal surface, preferentially produced in epithelial cells in contrast to type I interferon, and its function cannot be replaced by type I interferon. This review summarizes recent studies showing that IFN-λ inhibits the spread of viruses from the cell surface to the body. Further studies have found that the role of IFN-λ is not only limited to the abovementioned functions, but it can also can exert direct and/or indirect effects on immune cells in virus-induced inflammation. This review focuses on the antiviral activity of IFN-λ in the mucosal epithelial cells and its action on immune cells and summarizes the pathways by which IFN-λ exerts its action and differentiates it from other interferons in terms of mechanism. Finally, we conclude that IFN-λ is a potent epidermal antiviral factor that enhances the respiratory mucosal immune response and has excellent therapeutic potential in combating respiratory viral infections.

Targeting epidermal growth factor receptor signalling pathway: A promising therapeutic option for COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is continuously producing new variants, necessitating effective therapeutics. Patients are not only confronted by the immediate symptoms of infection but also by the long-term health issues linked to long COVID-19. Activation of epidermal growth factor receptor (EGFR) signalling during SARS-CoV-2 infection promotes virus propagation, mucus hyperproduction, and pulmonary fibrosis, and suppresses the host's antiviral response. Over the long term, EGFR activation in COVID-19, particularly in COVID-19-induced pulmonary fibrosis, may be linked to the development of lung cancer. In this review, we have summarised the significance of EGFR signalling in the context of SARS-CoV-2 infection. We also discussed the targeting of EGFR signalling as a promising strategy for COVID-19 treatment and highlighted erlotinib as a superior option among EGFR inhibitors. Erlotinib effectively blocks EGFR and AAK1, thereby preventing SARS-CoV-2 replication, reducing mucus hyperproduction, TNF-α expression, and enhancing the host's antiviral response. Nevertheless, to evaluate the antiviral efficacy of erlotinib, relevant clinical trials involving an appropriate patient population should be designed.

Role of Virus-Induced EGFR Trafficking in Proviral Functions

Since its discovery in the early 1980s, the epidermal growth factor receptor (EGFR) has emerged as a pivotal and multifaceted player in elucidating the intricate mechanisms underlying various human diseases and their associations with cell survival, proliferation, and cellular homeostasis. Recent advancements in research have underscored the profound and multifaceted role of EGFR in viral infections, highlighting its involvement in viral entry, replication, and the subversion of host immune responses. In this regard, the importance of EGFR trafficking has also been highlighted in recent studies. The dynamic relocation of EGFR to diverse intracellular organelles, including endosomes, lysosomes, mitochondria, and even the nucleus, is a central feature of its functionality in diverse contexts. This dynamic intracellular trafficking is not merely a passive process but an orchestrated symphony, facilitating EGFR involvement in various cellular pathways and interactions with viral components. Furthermore, EGFR, which is initially anchored on the plasma membrane, serves as a linchpin orchestrating viral entry processes, a crucial early step in the viral life cycle. The role of EGFR in this context is highly context-dependent and varies among viruses. Here, we present a comprehensive summary of the current state of knowledge regarding the intricate interactions between EGFR and viruses. These interactions are fundamental for successful propagation of a wide array of viral species and affect viral pathogenesis and host responses. Understanding EGFR significance in both normal cellular processes and viral infections may not only help develop innovative antiviral therapies but also provide a deeper understanding of the intricate roles of EGFR signaling in infectious diseases.

New pyrazolyl-thiazolidinone/thiazole derivatives as celecoxib/dasatinib analogues with selective COX-2, HER-2 and EGFR inhibitory effects: design, synthesis, anti-inflammatory/anti-proliferative activities, apoptosis, molecular modelling and ADME studies

Two new series of pyrazolyl-thiazolidinone/thiazole derivatives 16a-b and 18a-j were synthesised, merging the scaffolds of celecoxib and dasatinib. Compounds 16a, 16b and 18f inhibit COX-2 with S.I. 134.6, 26.08 and 42.13 respectively (celecoxib S.I. = 24.09). Compounds 16a, 16b, 18c, 18d and 18f inhibit MCF-7 with IC50 = 0.73-6.25 μM (dasatinib IC50 = 7.99 μM) and (doxorubicin IC50 = 3.1 μM) and inhibit A549 with IC50 = 1.64-14.3 μM (dasatinib IC50 = 11.8 μM and doxorubicin IC50 = 2.42 μM) with S.I. (F180/MCF7) of 33.15, 7.13, 18.72, 13.25 and 8.28 respectively higher than dasatinib (4.03) and doxorubicin (3.02) and S.I. (F180/A549) of 14.75, 12.96, 4.16, 7.07 and 18.88 respectively higher than that of dasatinib (S.I. = 2.72) and doxorubicin (S.I = 3.88). Derivatives 16a, 18c, 18d, 18f inhibit EGFR and HER-2 IC50 for EGFR of 0.043, 0.226, 0.388, 0.19 μM respectively and for HER-2 of 0.032, 0.144, 0.195, 0.201 μM respectively.

Sex-associated early-life viral innate immune response is transcriptionally associated with chromatin remodeling of type-I IFN-inducible genes

This study investigates sex-associated systemic innate immune differences by examining bone marrow-derived dendritic cells (BMDCs). BMDC grown from 7-day-old mice show enhanced type-I interferon (IFN) signaling in female compared to male BMDC. Upon respiratory syncytial virus (RSV) infection of 7-day-old mice, a significantly altered phenotype of BMDC at 4 weeks post-infection is observed in a sex-dependent manner. The alterations include heightened Ifnb/ interleukin (Il12a) and enhanced IFNAR1+ expression in BMDC from early-life RSV-infected female mice that leads to increased IFN-γ production by T cells. Phenotypic differences were verified upon pulmonary sensitization whereby EL-RSV male-derived BMDC promoted enhanced T helper 2/17 responses and exacerbated disease upon RSV infection while EL-RSV/F BMDC sensitization was relatively protective. Assay for transposase-accessible chromatin using sequencing analysis (ATAC-seq) demonstrated that EL-RSV/F BMDC had enhanced chromatin accessibility near type-I immune genes with JUN, STAT1/2, and IRF1/8 transcription factors predicted to have binding sites in accessible regions. Importantly, ATAC-seq of human cord blood-derived monocytes displayed a similar sex-associated chromatin landscape with female-derived monocytes having more accessibility in type-I immune genes. These studies enhance our understanding of sex-associated differences in innate immunity by epigenetically controlled transcriptional programs amplified by early-life infection in females via type-I immunity.

Syphilis and the host: multi-omic analysis of host cellular responses to Treponema pallidum provides novel insight into syphilis pathogenesis

Introduction

Syphilis is a chronic, multi-stage infection caused by the extracellular bacterium Treponema pallidum ssp. pallidum. Treponema pallidum widely disseminates through the vasculature, crosses endothelial, blood-brain and placental barriers, and establishes systemic infection. Although the capacity of T. pallidum to traverse the endothelium is well-described, the response of endothelial cells to T. pallidum exposure, and the contribution of this response to treponemal traversal, is poorly understood.

Methods

To address this knowledge gap, we used quantitative proteomics and cytokine profiling to characterize endothelial responses to T. pallidum.

Results

Proteomic analyses detected altered host pathways controlling extracellular matrix organization, necroptosis and cell death, and innate immune signaling. Cytokine analyses of endothelial cells exposed to T. pallidum revealed increased secretion of interleukin (IL)-6, IL-8, and vascular endothelial growth factor (VEGF), and decreased secretion of monocyte chemoattractant protein-1 (MCP-1).

Discussion

This study provides insight into the molecular basis of syphilis disease symptoms and the enhanced susceptibility of individuals infected with syphilis to HIV co-infection. These investigations also enhance understanding of the host response to T. pallidum exposure and the pathogenic strategies used by T. pallidum to disseminate and persist within the host. Furthermore, our findings highlight the critical need for inclusion of appropriate controls when conducting T. pallidum-host cell interactions using in vitro- and in vivo-grown T. pallidum.

Exploring the Immune Response against RSV and SARS-CoV-2 Infection in Children

Viral respiratory tract infections are a significant public health concern, particularly in children. RSV is a prominent cause of lower respiratory tract infections among infants, whereas SARS-CoV-2 has caused a global pandemic with lower overall severity in children than in adults. In this review, we aimed to compare the innate and adaptive immune responses induced by RSV and SARS-CoV-2 to better understand differences in the pathogenesis of infection. Some studies have demonstrated that children present a more robust immune response against SARS-CoV-2 than adults; however, this response is dissimilar to that of RSV. Each virus has a distinctive mechanism to escape the immune response. Understanding the mechanisms underlying these differences is crucial for developing effective treatments and improving the management of pediatric respiratory infections.

Interferons-Implications in the Immune Response to Respiratory Viruses

Interferons (IFN) are an assemblage of signaling proteins made and released by various host cells in response to stimuli, including viruses. Respiratory syncytial virus (RSV), influenza virus, and SARS-CoV-2 are major causes of respiratory disease that induce or antagonize IFN responses depending on various factors. In this review, the role and function of type I, II, and III IFN responses to respiratory virus infections are considered. In addition, the role of the viral proteins in modifying anti-viral immunity is noted, as are the specific IFN responses that underly the correlates of immunity and protection from disease.

Repurposing Axl Kinase Inhibitors for the Treatment of Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) infection persists as a common pathogen of pulmonary infection in infants and in the elderly with high morbidity and mortality. However, no specific therapeutics are available. Axl, a member of the TAM (Tyro3, Axl, and Mertk) family receptor kinases, is a pleiotropic inhibitor of the innate immune response and functions as a negative regulator of interferon pathway activation. In this report, we investigated Axl inhibitors for their effects against RSV infection. Axl inhibition with kinase inhibitors, including BMS-777607, R428, and TP-0903, or Axl ablation resulted in a significant reduction of RSV infection in cell-based assays. In an animal model of pulmonary RSV infection, treatment with BMS-777607, R428, or TP-0903 ameliorated pulmonary pathology with a significant reduction of RSV titers in the lung tissues and, consequently, decreased the expression of proinflammatory genes. The host promotes ISG expression for the antiviral response and for viral clearance. We found that Axl inhibition led to more robust IFN-β expression and antiviral gene induction. Thus, the results of this study imply that Axl kinase inhibitors may possess a broad spectrum of antiviral effects by promoting ISG expression.

Schizophrenia Animal Modeling with Epidermal Growth Factor and Its Homologs: Their Connections to the Inflammatory Pathway and the Dopamine System

Epidermal growth factor (EGF) and its homologs, such as neuregulins, bind to ErbB (Her) receptor kinases and regulate glial differentiation and dopaminergic/GABAergic maturation in the brain and are therefore implicated in schizophrenia neuropathology involving these cell abnormalities. In this review, we summarize the biological activities of the EGF family and its neuropathologic association with schizophrenia, mainly overviewing our previous model studies and the related articles. Transgenic mice as well as the rat/monkey models established by perinatal challenges of EGF or its homologs consistently exhibit various behavioral endophenotypes relevant to schizophrenia. In particular, post-pubertal elevation in baseline dopaminergic activity may illustrate the abnormal behaviors relevant to positive and negative symptoms as well as to the timing of this behavioral onset. With the given molecular interaction and transactivation of ErbB receptor kinases with Toll-like receptors (TLRs), EGF/ErbB signals are recruited by viral infection and inflammatory diseases such as COVID-19-mediated pneumonia and poxvirus-mediated fibroma and implicated in the immune-inflammatory hypothesis of schizophrenia. Finally, we also discuss the interaction of clozapine with ErbB receptor kinases as well as new antipsychotic development targeting these receptors.

Expressions of Type I and III Interferons, Endogenous Retroviruses, TRIM28, and SETDB1 in Children with Respiratory Syncytial Virus Bronchiolitis

Interferons (IFNs) and IFN-stimulated genes (ISGs) play essential roles for the control of viral infections. Their expression in infants with respiratory syncytial virus (RSV) bronchiolitis is poorly defined. Human endogenous retroviruses (HERVs) represent 8% of our genome and modulate inflammatory and immune reactions. TRIM28 and SETDB1 participate in the epigenetic regulation of genes involved in the immune response, including IFNs and HERVs. No study has explored the expression of HERVs, TRIM28, and SETDB1 during RSV bronchiolitis. We assessed, through a PCR real-time Taqman amplification assay, the transcription levels of six IFN-I ISGs, four IFNλs, the pol genes of HERV-H, -K, and -W families, the env genes of Syncytin (SYN)1 and SYN2, and of TRIM28/SETDB1 in whole blood from 37 children hospitalized for severe RSV bronchiolitis and in healthy children (HC). The expression of most IFN-I ISGs was significantly higher in RSV+ patients than in age-matched HC, but it was inhibited by steroid therapy. The mRNA concentrations of IFN-λs were comparable between patients and age-matched HC. This lack of RSV-driven IFN-III activation may result in the defective protection of the airway mucosal surface leading to severe bronchiolitis. The expression of IFN-III showed a positive correlation with age in HC, that could account for the high susceptibility of young children to viral respiratory tract infections. The transcription levels of every HERV gene were significantly lower in RSV+ patients than in HC, while the expressions of TRIM28/SETDB1 were overlapping. Given the negative impact of HERVs and the positive effects of TRIM28/SETDB1 on innate and adaptive immune responses, the downregulation of the former and the normal expression of the latter may contribute to preserving immune functions against infection.

Respiratory syncytial virus: host genetic susceptibility and factors associated with disease severity in a cohort of pediatric patients

BACKGROUND

Respiratory syncytial virus (RSV) infections are the leading cause of hospitalization in young children. We assessed the epidemiology, severity, clinical characteristics, molecular profile and genetic factors of RSV infections compared to acute respiratory illness (ARI) caused by other respiratory viruses.

METHODS

Prospective cohort study was conducted from 2017 to 2018 with children under 2 years old hospitalized with ARI. Detection of respiratory viruses was carried out using RT-PCR. RSVs were genotyped via nucleotide sequencing, and host interleukin 28B (IL28B) single nucleotide polymorphisms (SNPs) were determined using SNP TaqMan® Genotyping Assays.

RESULTS

A total of 468 children were included; 288 (61.5%) had an infection by a single virus: 202 (70.1%) cases by RSV followed by rhinovirus 36 (12.5%) and influenza 16 (5.6%). Of the RSV cases, 36% were genotyped with a higher prevalence of RSV B (62.1%). The RSV group presented median age of 2.7 months (1.6-6.8), higher frequency in: intensive care unit admission (p = 0.004), mechanical ventilation use (p = 0.018), wheezing (p < 0.001), antimicrobial use (p < 0.001) and low oxygen saturation (p < 0.001). Prematurity (27.2%) was the most frequent comorbidity. RSV patients without comorbidities demonstrated a higher frequency in the combination of IL28B rs12979860 CT/IL28B rs8099917 TG and IL28B rs12979860 TT/IL28B rs8099917 TT genotypes. Viral coinfection was detected in 27 (5.7%) children, with the most frequent being RSV and rhinovirus (14.2%).

CONCLUSIONS

This study highlighted the burden of RSV infection in children under 2 years of age, without comorbidities, with a higher need for pediatric ICU admission. Some IL28B allele combinations had a significant association with RSV frequency of infections.

Epidermal Growth Factor Receptor Inhibition Is Protective in Hyperoxia-Induced Lung Injury

Aims

Studies have linked severe hyperoxia, or prolonged exposure to very high oxygen levels, with worse clinical outcomes. This study investigated the role of epidermal growth factor receptor (EGFR) in hyperoxia-induced lung injury at very high oxygen levels (>95%).

Results

Effects of severe hyperoxia (100% oxygen) were studied in mice with genetically inhibited EGFR and wild-type littermates. Despite the established role of EGFR in lung repair, EGFR inhibition led to improved survival and reduced acute lung injury, which prompted an investigation into this protective mechanism. Endothelial EGFR genetic knockout did not confer protection. EGFR inhibition led to decreased levels of cleaved caspase-3 and poly (ADP-ribosyl) polymerase (PARP) and decreased terminal dUTP nick end labeling- (TUNEL-) positive staining in alveolar epithelial cells and reduced ERK activation, which suggested reduced apoptosis in vivo. EGFR inhibition decreased hyperoxia (95%)-induced apoptosis and ERK in murine alveolar epithelial cells in vitro, and CRISPR-mediated EGFR deletion reduced hyperoxia-induced apoptosis and ERK in human alveolar epithelial cells in vitro. Innovation. This work defines a protective role of EGFR inhibition to decrease apoptosis in lung injury induced by 100% oxygen. This further characterizes the complex role of EGFR in acute lung injury and outlines a novel hyperoxia-induced cell death pathway that warrants further study.

Conclusion

In conditions of severe hyperoxia (>95% for >24 h), EGFR inhibition led to improved survival, decreased lung injury, and reduced cell death. These findings further elucidate the complex role of EGFR in acute lung injury.

ITGB4 Deficiency in Airway Epithelium Aggravates RSV Infection and Increases HDM Sensitivity

Background

The heterogeneity of RSV-infected pathology phenotype in early life is strongly associate with increased susceptibility of asthma in later life. However, the inner mechanism of this heterogeneity is still obscure. ITGB4 is a down-regulated adhesion molecular in the airway epithelia of asthma patients which may participate in the regulation of RSV infection related intracellular pathways.

Object

This study was designed to observe the involvement of ITGB4 in the process of RSV infection and the effect of ITGB4 deficiency on anti-RSV responses of airway epithelia.

Results

RSV infection caused a transient decrease of ITGB4 expression both in vitro and in vivo. Besides, ITGB4 deficiency induced not only exacerbated RSV infection, but also enhanced HDM sensitivity in later life. Moreover, IFN III (IFN-λ) was significantly suppressed during RSV infection in ITGB4 deficient airway epithelial cells. Furthermore, the suppression of IFN-λ were regulated by IRF-1 through the phosphorylation of EGFR in airway epithelial cells after RSV infection.

Conclusion

These results demonstrated the involvement of ITGB4 deficiency in the development of enhance RSV infection in early life and the increased HDM sensitivity in later life by down-regulation of IFN-λ through EGFR/IRF-1 pathway in airway epithelial cells.

A New EGFR Inhibitor from Ficus benghalensis Exerted Potential Anti-Inflammatory Activity via Akt/PI3K Pathway Inhibition

Inflammation is a critical defensive mechanism mainly arising due to the production of prostaglandins via cyclooxygenase enzymes. This study aimed to examine the anti-inflammatory activity of fatty acid glucoside (FAG), which is isolated from Ficus benghalensis against lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. The cytotoxic activity of the FAG on RAW 264.7 macrophages was evaluated with an MTT assay. The levels of PGE2 and NO and the activity of iNOS, COX-1, and COX-2 enzymes in LPS-stimulated RAW 264.7 cells were evaluated. The gene expression of IL-6, TNF-α, and PGE2 was investigated by qRT-PCR. The expression of epidermal growth factor receptor (EGFR), Akt, and PI3K proteins was examined using Western blotting analysis. Furthermore, molecular docking of the new FAG against EGFR was investigated. A non-cytotoxic concentration of FAG increased NO release and iNOS activity, inhibited COX-1 and COX-2 activities, and reduced PGE2 levels in LPS-stimulated RAW 264.7 cells. It diminished the expression of TNF-α, IL-6, PGE2, EGFR, Akt, and PI3K. Furthermore, the molecular docking study proposed the potential direct binding of FAG with EGFR with a high affinity. This study showed that FAG is a natural EGFR inhibitor, NO-releasing, and COX-inhibiting anti-inflammatory agent via EGFR/Akt/PI3K pathway inhibition.

EGFR Activation Impairs Antiviral Activity of Interferon Signaling in Brain Microvascular Endothelial Cells During Japanese Encephalitis Virus Infection

The establishment of Japanese encephalitis virus (JEV) infection in brain microvascular endothelial cells (BMECs) is thought to be a critical step to induce viral encephalitis with compromised blood–brain barrier (BBB), and the mechanisms involved in this process are not completely understood. In this study, we found that epidermal growth factor receptor (EGFR) is related to JEV escape from interferon-related host innate immunity based on a STRING analysis of JEV-infected primary human brain microvascular endothelial cells (hBMECs) and mouse brain. At the early phase of the infection processes, JEV induced the phosphorylation of EGFR. In JEV-infected hBMECs, a rapid internalization of EGFR that co-localizes with the endosomal marker EEA1 occurred. Using specific inhibitors to block EGFR, reduced production of viral particles was observed. Similar results were also found in an EGFR-KO hBMEC cell line. Even though the process of viral infection in attachment and entry was not noticeably influenced, the induction of IFNs in EGFR-KO hBMECs was significantly increased, which may account for the decreased viral production. Further investigation demonstrated that EGFR downstream cascade ERK, but not STAT3, was involved in the antiviral effect of IFNs, and a lowered viral yield was observed by utilizing the specific inhibitor of ERK. Taken together, the results revealed that JEV induces EGFR activation, leading to a suppression of interferon signaling and promotion of viral replication, which could provide a potential target for future therapies for the JEV infection.

The roles of epidermal growth factor receptor in viral infections

Viruses are intracellular pathogen that exploit host cellular machinery for their propagation. Extensive research on virus-host interaction have shed light on an alternative antiviral strategy that targets host cell factors. Epidermal growth factor receptor (EGFR) is a versatile signal transducer that is involved in a range of cellular processes. Numerous studies have revealed how viruses exploit the function of EGFR in different stages of viral life cycle. In general, viruses attach onto the host cell surface and interacts with EGFR to facilitate viral entry, viral replication and spread as well as evasion from host immunosurveillance. Moreover, virus-induced activation of EGFR signalling is associated with mucin expression, tissue damage and carcinogenesis that contribute to serious complications. Herein, we review our current understanding of roles of EGFR in viral infection and its potential as therapeutic target in managing viral infection. We also discuss the available EGFR-targeted therapies and their limitations.

Extracellular Nucleotides and Histamine Suppress TLR3- and RIG-I-Mediated Release of Antiviral IFNs from Human Airway Epithelial Cells

Respiratory viruses stimulate the release of antiviral IFNs from the airway epithelium. Previous studies have shown that asthmatic patients show diminished release of type I and type III IFNs from bronchial epithelia. However, the mechanism of this suppression is not understood. In this study, we report that extracellular nucleotides and histamine, which are elevated in asthmatic airways, strongly inhibit release of type I and type III IFNs from human bronchial airway epithelial cells (AECs). Specifically, ATP, UTP, and histamine all inhibited the release of type I and type III IFNs from AECs induced by activation of TLR3, retinoic acid-inducible gene I (RIG-I), or cyclic GMP-AMP synthase-STING. This inhibition was at least partly mediated by Gq signaling through purinergic P2Y2 and H1 receptors, but it did not involve store-operated calcium entry. Pharmacological blockade of protein kinase C partially reversed inhibition of IFN production. Conversely, direct activation of protein kinase C with phorbol esters strongly inhibited TLR3- and RIG-I-mediated IFN production. Inhibition of type I and type III IFNs by ATP, UTP, histamine, and the proteinase-activated receptor 2 (PAR2) receptor agonist SLIGKV also occurred in differentiated AECs grown at an air-liquid interface, indicating that the suppression is conserved following mucociliary differentiation. Importantly, histamine and, more strikingly, ATP inhibited type I IFN release from human airway cells infected with live influenza A virus or rhinovirus 1B. These results reveal an important role for extracellular nucleotides and histamine in attenuating the induction of type I and III IFNs from AECs and help explain the molecular basis of the suppression of IFN responses in asthmatic patients.

Axl Mediates Resistance to Respiratory Syncytial Virus Infection Independent of Cell Attachment

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract infections in infants and young children. Axl, a TAM family receptor tyrosine kinase (RTK), has been demonstrated as a receptor mediating enveloped virus infection. Here we show that Axl functions as a suppressor of antiviral response during RSV infection. Knockdown of Axl expression in human cells resulted in cell resistance to RSV infection although the treatment did not significantly affect RSV binding or cell entry. Mice deficiency of Axl showed resistance to RSV infection including reduction in viral load and in pulmonary injury. Although T lymphocyte and macrophage infiltration was reduced, more IFN-γ producing cells were present in BALF in Axl-/- mice. Less alternatively activated alveolar macrophages were found in the lungs of Axl-/- mice. Axl-/- MEF cells and siRNA-treated human cells had more robust IFN-β and ISG induction of antiviral genes. Furthermore, re-expression of Axl using Ad-mediated Axl delivery repressed ISG induction in Axl-null MEF cells by RSV infection. The results suggest that Axl, independent of being a virus entry receptor of RSV infection, negatively regulates interferon signaling to modulate host antiviral response against RSV infection.

Ingestion, Immunity, and Infection: Nutrition and Viral Respiratory Tract Infections

Respiratory infections place a heavy burden on the health care system, particularly in the winter months. Individuals with a vulnerable immune system, such as very young children and the elderly, and those with an immune deficiency, are at increased risk of contracting a respiratory infection. Most respiratory infections are relatively mild and affect the upper respiratory tract only, but other infections can be more serious. These can lead to pneumonia and be life-threatening in vulnerable groups. Rather than focus entirely on treating the symptoms of infectious disease, optimizing immune responsiveness to the pathogens causing these infections may help steer towards a more favorable outcome. Nutrition may have a role in such prevention through different immune supporting mechanisms. Nutrition contributes to the normal functioning of the immune system, with various nutrients acting as energy sources and building blocks during the immune response. Many micronutrients (vitamins and minerals) act as regulators of molecular responses of immune cells to infection. It is well described that chronic undernutrition as well as specific micronutrient deficiencies impair many aspects of the immune response and make individuals more susceptible to infectious diseases, especially in the respiratory and gastrointestinal tracts. In addition, other dietary components such as proteins, pre-, pro- and synbiotics, and also animal- and plant-derived bioactive components can further support the immune system. Both the innate and adaptive defense systems contribute to active antiviral respiratory tract immunity. The initial response to viral airway infections is through recognition by the innate immune system of viral components leading to activation of adaptive immune cells in the form of cytotoxic T cells, the production of neutralizing antibodies and the induction of memory T and B cell responses. The aim of this review is to describe the effects of a range different dietary components on anti-infective innate as well as adaptive immune responses and to propose mechanisms by which they may interact with the immune system in the respiratory tract.

Gene-Based Analysis Reveals Sex-Specific Genetic Risk Factors of COPD

Sex-specific differences have been noted among people with chronic obstructive pulmonary disease (COPD), but whether these differences are attributable to genetic variation is poorly understood. The availability of large biobanks with deeply phenotyped subjects such as the UK Biobank enables the investigation of sex-specific genetic associations that may provide new insights into COPD risk factors. We performed sex-stratified genome-wide association studies (GWAS) of COPD (male: 12,958 cases and 95,631 controls; female: 11,311 cases and 123,714 controls) and found that while most associations were shared between sexes, several regions had sex-specific contributions, including respiratory viral infection-related loci in/near C5orf56 and PELI1. Using the newly developed R package 'snpsettest', we performed gene-based association tests and identified gene-level sex-specific associations, including C5orf56 on 5q31.1, CFDP1/TMEM170A/CHST6 on 16q23.1 and ASTN2/TRIM32 on 9q33.1. Our results identified promising genes to pursue in functional studies to better understand sexual dimorphism in COPD.

How RSV Proteins Join Forces to Overcome the Host Innate Immune Response

Respiratory syncytial virus (RSV) is the leading cause of severe acute lower respiratory tract infections in infants worldwide. Although several pattern recognition receptors (PRRs) can sense RSV-derived pathogen-associated molecular patterns (PAMPs), infection with RSV is typically associated with low to undetectable levels of type I interferons (IFNs). Multiple RSV proteins can hinder the host’s innate immune response. The main players are NS1 and NS2 which suppress type I IFN production and signalling in multiple ways. The recruitment of innate immune cells and the production of several cytokines are reduced by RSV G. Next, RSV N can sequester immunostimulatory proteins to inclusion bodies (IBs). N might also facilitate the assembly of a multiprotein complex that is responsible for the negative regulation of innate immune pathways. Furthermore, RSV M modulates the host’s innate immune response. The nuclear accumulation of RSV M has been linked to an impaired host gene transcription, in particular for nuclear-encoded mitochondrial proteins. In addition, RSV M might also directly target mitochondrial proteins which results in a reduced mitochondrion-mediated innate immune recognition of RSV. Lastly, RSV SH might prolong the viral replication in infected cells and influence cytokine production.

Distribution of Interferon Lambda 4 Single Nucleotide Polymorphism rs11322783 Genotypes in Patients with COVID-19

Type III interferons (IFN-III), also known as IFN-Lambda, have a pivotal role during SARS-CoV-2 infection. IFN-Lambda response among individuals is heterogeneous and its association with COVID-19 symptoms severity needs to be further clarified. We analyzed the genotype frequencies of IFNL4 single nucleotide polymorphism (SNP) rs11322783 in patients with COVID-19 (n = 128), in comparison with a validated data set of European healthy controls (n = 14152). The IFNL4 SNP was also analyzed according to the haematological and clinical parameters of patients with COVID-19. The distributions of IFNL4 genotypes among SARS-CoV-2 positive patients [TT/TT 41.4% (n = 53), TT/ΔG 47.7% (n = 61) and ΔG/ΔG 10.9% (n = 14)] and healthy controls were comparable. Different levels of white blood cells (p = 0.036) and neutrophils (p = 0.042) were found in the IFNL4 different genotypes in patients with COVID-19; the ΔG/ΔG genotype was more represented in the groups with low white blood cells and neutrophils. There were no differences in major inflammation parameters (C-reactive protein, D-dimer, Albumin, and Lactate-dehydrogenase (LDH)] and survival rate according to the IFNL4 genotypes. In conclusion, although patients with COVID-19 did not exhibit a different distribution of the IFNL4 SNP, the ΔG/ΔG genotype was associated with a lower count of immune cell populations. These findings need to be confirmed in larger groups of patients with COVID-19 and the role of IFNL4 SNP needs to be also investigated in other respiratory viral infections.

Role of EGF Receptor Regulatory Networks in the Host Response to Viral Infections

In this review article, we will first provide a brief overview of EGF receptor (EGFR) structure and function, and its importance as a therapeutic target in epithelial carcinomas. We will then compare what is currently known about canonical EGFR trafficking pathways that are triggered by ligand binding, versus ligand-independent pathways activated by a variety of intrinsic and environmentally induced cellular stresses. Next, we will review the literature regarding the role of EGFR as a host factor with critical roles facilitating viral cell entry and replication. Here we will focus on pathogens exploiting virus-encoded and endogenous EGFR ligands, as well as EGFR-mediated trafficking and signaling pathways that have been co-opted by wild-type viruses and recombinant gene therapy vectors. We will also provide an overview of a recently discovered pathway regulating non-canonical EGFR trafficking and signaling that may be a common feature of viruses like human adenoviruses which signal through p38-mitogen activated protein kinase. We will conclude by discussing the emerging role of EGFR signaling in innate immunity to viral infections, and how viral evasion mechanisms are contributing to our understanding of fundamental EGFR biology.

Something Is Changing in Viral Infant Bronchiolitis Approach

Acute Viral Bronchiolitis is one of the leading causes of hospitalization in the first 12-24 months of life. International guidelines on the management of bronchiolitis broadly agree in recommending a minimal therapeutic approach, not recommending the use of bronchodilators. Guidelines, generally, consider bronchiolitis as a "unique disease" and this runs the risk of not administering therapy in some patients who could benefit from the use of bronchodilators, for instance, in those who will develop asthma later in their life and face first episode in the age of bronchiolitis. Today, there is growing evidence that bronchiolitis is not a single illness but can have different "endotypes" and "phenotypes," based on age, personal or family history of atopy, etiology, and pathophysiological mechanism. There is evidence that some phenotypes of bronchiolitis are more strongly associated with asthma features and are linked to higher risk for asthma development. In these populations, possible use of bronchodilators might have a better impact. Age seems to be the main feature to suggest a good response to a bronchodilator-trial, because, among children > 6 months old with bronchiolitis, the presence of a subset of patients with virus-induced wheezing or the first episode of asthma is more likely. While waiting for new research to define the relationship between therapeutic options and different phenotypes, a bronchodilator-trial (using short-acting β2 agonists with metered-dose inhalers and valved holding chambers) seems appropriate in every child with bronchiolitis and age > 6 months.

OASL1-Mediated Inhibition of Type I IFN Reduces Influenza A Infection-Induced Airway Inflammation by Regulating ILC2s

Purpose

Three observations drove this study. First, 2′-5′-oligoadenylate synthetase-like protein (OASL) is a negative regulator of type I interferon (IFN). Second, type I IFN plays a central role during virus infections and the pathogenesis of various diseases, including asthma. Third, influenza A virus (IAV) causes non-eosinophilic asthma. To evaluate the potential relationships between OASL, type I IFN, and pulmonary innate immune cells in IAV-induced acute airway inflammation by using Oasl1^-/- mice.

Methods

Asthma was induced in wild-type (WT) and Oasl1^-/- mice with IAV or ovalbumin (OVA). Airway hyperreactivity (AHR) and immune cell infiltration in the bronchoalveolar lavage (BAL) fluids were measured. The immune cells in the lungs were analyzed by flow cytometry. To investigate the ability of type I IFN to shape the response of lung type 2 innate lymphoid cells (ILC2s), IFN-α was treated intratracheally. Plasmacytoid dendritic cells (pDCs) sorted from bone marrow and ILC2s sorted from lungs of naive mice were co-cultured with/without interferon-alpha receptor subunit 1 (IFNAR-1)-blocking antibodies.

Results

In the IAV-induced asthma model, Oasl1^-/- mice developed greater AHR and immune cell infiltration in the BAL fluids than WT mice. This was not observed in OVA-induced asthma, a standard model of allergen-induced asthma. The lungs of infected Oasl1^-/- mice also had elevated DC numbers and Ifna expression and depressed IAV-induced ILC2 responses, namely, proliferation and type 2 cytokine and amphiregulin production. Intratracheal administration of type I IFN in naïve mice suppressed lung ILC2 production of type 2 cytokines and amphiregulin. Co-culture of ILC2s with pDCs showed that pDCs inhibit the function of ILC2s by secreting type I IFN.

Conclusions

OASL1 may impede the IAV-induced acute airway inflammation that drives AHR by inhibiting IAV-induced type I IFN production from lung DCs, thereby preserving the functions of lung ILC2s, including their amphiregulin production.

Immunopathology of RSV: An Updated Review

RSV is a leading cause of respiratory tract disease in infants and the elderly. RSV has limited therapeutic interventions and no FDA-approved vaccine. Gaps in our understanding of virus-host interactions and immunity contribute to the lack of biological countermeasures. This review updates the current understanding of RSV immunity and immunopathology with a focus on interferon responses, animal modeling, and correlates of protection.

A Study Based on Metabolomics, Network Pharmacology, and Experimental Verification to Explore the Mechanism of Qinbaiqingfei Concentrated Pills in the treatment of Mycoplasma Pneumonia

Qinbaiqingfei concentrated pills (QB) are a commonly used medicine for the treatment of mycoplasma pneumonia in China, and the mechanism of action of QB needs to be studied further. Therefore, we use a combination of metabolomics and network pharmacology to clarify the mechanism of QB. Nontarget metabolomics studies were performed on rat serum, urine, and lung tissues, and 56 therapeutic biomarkers were found. Subsequently, the components of QB absorbed into the blood and lung tissues were clarified, and based on this finding, the core target of network pharmacology was predicted. The enrichment analysis of biomarkers–genes finally confirmed their close relationship with the NF-κB signaling pathway. By western blotting expression of the proteins in the lung tissue–related signaling pathways, it is finally confirmed that QB inhibits the NF-κB signaling pathway through SIRT1, IL-10 and MMP9, CTNNB1, EGFR, and other targets. It plays a role in regulating immunity, regulating metabolism, and treating diseases.

New preventive strategies for respiratory syncytial virus infection in children

Respiratory syncytial virus (RSV) infections result in significant morbidity and mortality for young children worldwide. The development of preventive strategies for RSV has faced different challenges, including the legacy of the first vaccine attempt, and an incomplete understanding of the host immune response to the virus. However, promising preventive strategies against RSV are in the pipeline and their development has advanced rapidly in the past decade due in part to our improved knowledge about the structural conformation of key RSV proteins. These strategies include monoclonal antibodies and different vaccines platforms directed towards the main target populations.

Emerging cellular and molecular interactions between the lung microbiota and lung diseases

With the discovery of the lung microbiota, its study in both pulmonary health and disease has become a vibrant area of emerging research interest. Thus far, most studies have described the lung microbiota composition in lung disease quite well, and some of these studies indicated alterations in lung microbial communities related to the onset and development of lung disease and vice versa. However, the underlying mechanisms, particularly the cellular and molecular links, are still largely unknown. In this review, we highlight the current progress in the complex cellular and molecular mechanisms by which the lung microbiome interacts with immune homeostasis and pulmonary disease pathogenesis to advance our understanding of the elaborate function of the lung microbiota in lung disease. We hope that this work can attract more attention to this still-young yet very promising field to facilitate the identification of new therapeutic targets and provide more innovative therapies. Additional accurate standard-based methodologies and technological breakthroughs are critical to propel the field forward to ultimately achieve the goal of maintaining respiratory health.

Respiratory syncytial virus: from pathogenesis to potential therapeutic strategies

Respiratory syncytial virus (RSV) is one of the most important viral pathogens causing respiratory tract infection in infants, the elderly and people with poor immune function, which causes a huge disease burden worldwide every year. It has been more than 60 years since RSV was discovered, and the palivizumab monoclonal antibody, the only approved specific treatment, is limited to use for passive immunoprophylaxis in high-risk infants; no other intervention has been approved to date. However, in the past decade, substantial progress has been made in characterizing the structure and function of RSV components, their interactions with host surface molecules, and the host innate and adaptive immune response to infection. In addition, basic and important findings have also piqued widespread interest among researchers and pharmaceutical companies searching for effective interventions for RSV infection. A large number of promising monoclonal antibodies and inhibitors have been screened, and new vaccine candidates have been designed for clinical evaluation. In this review, we first briefly introduce the structural composition, host cell surface receptors and life cycle of RSV virions. Then, we discuss the latest findings related to the pathogenesis of RSV. We also focus on the latest clinical progress in the prevention and treatment of RSV infection through the development of monoclonal antibodies, vaccines and small-molecule inhibitors. Finally, we look forward to the prospects and challenges of future RSV research and clinical intervention.

Protectins PCTR1 and PD1 Reduce Viral Load and Lung Inflammation During Respiratory Syncytial Virus Infection in Mice

Viral pneumonias are a major cause of morbidity and mortality, owing in part to dysregulated excessive lung inflammation, and therapies to modulate host responses to viral lung injury are urgently needed. Protectin conjugates in tissue regeneration 1 (PCTR1) and protectin D1 (PD1) are specialized pro-resolving mediators (SPMs) whose roles in viral pneumonia are of interest. In a mouse model of Respiratory Syncytial Virus (RSV) pneumonia, intranasal PCTR1 and PD1 each decreased RSV genomic viral load in lung tissue when given after RSV infection. Concurrent with enhanced viral clearance, PCTR1 administration post-infection, decreased eosinophils, neutrophils, and NK cells, including NKG2D+ activated NK cells, in the lung. Intranasal PD1 administration post-infection decreased lung eosinophils and Il-13 expression. PCTR1 increased lung expression of cathelicidin anti-microbial peptide and decreased interferon-gamma production by lung CD4+ T cells. PCTR1 and PD1 each increased interferon-lambda expression in human bronchial epithelial cells in vitro and attenuated RSV-induced suppression of interferon-lambda in mouse lung in vivo. Liquid chromatography coupled with tandem mass spectrometry of RSV-infected and untreated mouse lungs demonstrated endogenous PCTR1 and PD1 that decreased early in the time course while cysteinyl-leukotrienes (cys-LTs) increased during early infection. As RSV infection resolved, PCTR1 and PD1 increased and cys-LTs decreased to pre-infection levels. Together, these results indicate that PCTR1 and PD1 are each regulated during RSV pneumonia, with overlapping and distinct mechanisms for PCTR1 and PD1 during the resolution of viral infection and its associated inflammation.

Development of a fixed module repertoire for the analysis and interpretation of blood transcriptome data

As the capacity for generating large-scale molecular profiling data continues to grow, the ability to extract meaningful biological knowledge from it remains a limitation. Here, we describe the development of a new fixed repertoire of transcriptional modules, BloodGen3, that is designed to serve as a stable reusable framework for the analysis and interpretation of blood transcriptome data. The construction of this repertoire is based on co-clustering patterns observed across sixteen immunological and physiological states encompassing 985 blood transcriptome profiles. Interpretation is supported by customized resources, including module-level analysis workflows, fingerprint grid plot visualizations, interactive web applications and an extensive annotation framework comprising functional profiling reports and reference transcriptional profiles. Taken together, this well-characterized and well-supported transcriptional module repertoire can be employed for the interpretation and benchmarking of blood transcriptome profiles within and across patient cohorts. Blood transcriptome fingerprints for the 16 reference cohorts can be accessed interactively via:  https://drinchai.shinyapps.io/BloodGen3Module/ .

Human Metapneumovirus Induces IRF1 via TANK-Binding Kinase 1 and Type I IFN

The innate immune and host-protective responses to viruses, such as the airway pathogen human metapneumovirus (HMPV), depend on interferons (IFNs) that is induced through TANK-binding kinase 1 (TBK1) and IFN regulatory factors (IRFs). The transcription factor IRF1 is important for host resistance against several viruses and has a key role in induction of IFN-λ at mucosal surfaces. In most cell types IRF1 is expressed at very low levels, but its mRNA is rapidly induced when the demand for IRF1 activity arises. Despite general recognition of the importance of IRF1 to antiviral responses, the molecular mechanisms by which IRF1 is regulated during viral infections are not well understood. Here we identify the serine/threonine kinase TBK1 and IFN-β as critical regulators of IRF1 mRNA and protein levels in human monocyte-derived macrophages. We find that inhibition of TBK1 activity either by the semi-selective TBK1/IKKε inhibitor BX795 or by siRNA-mediated knockdown abrogates HMPV-induced expression of IRF1. Moreover, we show that canonical NF-κB signaling is involved in IRF1 induction and that the TBK1/IKKε inhibitor BX795, but not siTBK1 treatment, impairs HMPV-induced phosphorylation of the NF-κB subunit p65. At later time-points of the infection, IRF1 expression depended heavily on IFN-β-mediated signaling via the IFNAR-STAT1 pathway. Hence, our results suggest that TBK1 activation and TBK1/IKKε-mediated phosphorylation of the NF-κB subunit p65 control transcription of IRF1. Our study identifies a novel mechanism for IRF1 induction in response to viral infection of human macrophages that could be relevant not only to defense against HMPV, but also to other viral, bacterial and fungal pathogens.

Design, synthesis, and biological evaluation of new pyrimidine-5-carbonitrile derivatives bearing 1,3-thiazole moiety as novel anti-inflammatory EGFR inhibitors with cardiac safety profile

A new series of pyrimidine-5-carbonitrile derivatives 8a-p carrying the 1,3-thiazole moiety has been designed and synthesized as novel anti-inflammatory EGFR inhibitors with cardiac and gastric safety profiles. 8a-p have been assessed for their inhibitory activity against COX-1/COX-2 activity. Compounds 8h, 8n, and 8p were found to be potent and selective COX-2 inhibitors (IC₅₀ = 1.03-1.71 μM) relative to celecoxib (IC₅₀ = 0.88 μM). The most potent COX-2 inhibitors have been further investigated for their in-vivo anti-inflammatory effect. Compounds 8h, 8n, and 8p showed anti-inflammatory activity up to 90%, 94% and 86% of meloxicam after 4 h interval. 8h, 8n, and 8p showed higher gastric safety profiles than meloxicam. A substantial reduction in serum concentrations of PGE₂, TNF-α, IL-6, iNO and MDA and a significant induction of TAC was also observed. In vivo experiments on heart rate and blood pressure established the cardiovascular safety profile of 8h, 8n, and 8p. Anti-proliferative and wild-type EGFR inhibitory assays displayed similar results to selective COX-2 inhibition where compounds 8h, 8n, and 8p had a superior inhibition than other tested ones. Molecular docking study demonstrated that these compounds revealed similar orientation and binding interactions as selective COX-2 inhibitors with a higher liability to enter the side pocket selectively. Also, they interacted with EGFR tyrosine kinase main amino acids similar to erlotinib with a strong binding energy score.

Respiratory syncytial virus activates Rab5a to suppress IRF1-dependent IFN-λ production, subverting the antiviral defense of airway epithelial cells

The limited antiviral options and lack of an effective vaccine against human respiratory syncytial virus (RSV) highlight the need for a novel antiviral therapy. One alternative is to identify and target the host factors required for viral infection. Here, using RNA interference to knock down Rab proteins, we provide multiple lines of evidence that Rab5a is required for RSV infection: (a) Rab5a is upregulated both in RSV-A2-infected A549 cells and RSV-A2-challenged BALB/c mice's airway epithelial cells at early infection phase; (b) shRNA-mediated knockdown of Rab5a is associated with reduced lung pathology in RSV A2 challenged mice; (c) Rab5a expression is correlated with disease severity of RSV infection of infants. Knockdown of Rab5a increases IFN-λ (lambda) production by mediating IRF1 nuclear translocation. Our results highlight a new role for Rab5a in RSV infection, such that its depletion inhibits RSV infection by stimulating the endogenous respiratory epithelial antiviral immunity, which suggests that Rab5a is a potential target for novel therapeutics against RSV infection.Importance This study highlights the important role of Rab5a in RSV infection, such that its depletion inhibits RSV infection by stimulating the endogenous respiratory epithelial antiviral immunity and attenuates inflammation of the airway, which suggests that Rab5a is a powerful potential target for novel therapeutics against RSV infection.

Human RNase3 immune modulation by catalytic-dependent and independent modes in a macrophage-cell line infection model

The human RNase3 is a member of the RNaseA superfamily involved in host immunity. RNase3 is expressed by leukocytes and shows broad-spectrum antimicrobial activity. Together with a direct antimicrobial action, RNase3 exhibits immunomodulatory properties. Here, we have analysed the transcriptome of macrophages exposed to the wild-type protein and a catalytic-defective mutant (RNase3-H15A). The analysis of differently expressed genes (DEGs) in treated THP1-derived macrophages highlighted a common pro-inflammatory "core-response" independent of the protein ribonucleolytic activity. Network analysis identified the epidermal growth factor receptor (EGFR) as the main central regulatory protein. Expression of selected DEGs and MAPK phosphorylation were inhibited by an anti-EGFR antibody. Structural analysis suggested that RNase3 activates the EGFR pathway by direct interaction with the receptor. Besides, we identified a subset of DEGs related to the protein ribonucleolytic activity, characteristic of virus infection response. Transcriptome analysis revealed an early pro-inflammatory response, not associated to the protein catalytic activity, followed by a late activation in a ribonucleolytic-dependent manner. Next, we demonstrated that overexpression of macrophage endogenous RNase3 protects the cells against infection by Mycobacterium aurum and the human respiratory syncytial virus. Comparison of cell infection profiles in the presence of Erlotinib, an EGFR inhibitor, revealed that the receptor activation is required for the antibacterial but not for the antiviral protein action. Moreover, the DEGs related and unrelated to the protein catalytic activity are associated to the immune response to bacterial and viral infection, respectively. We conclude that RNase3 modulates the macrophage defence against infection in both catalytic-dependent and independent manners.

The roles of signaling pathways in SARS-CoV-2 infection; lessons learned from SARS-CoV and MERS-CoV

The number of descriptions of emerging viruses has grown at an unprecedented rate since the beginning of the 21st century. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), is the third highly pathogenic coronavirus that has introduced itself into the human population in the current era, after SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV). Molecular and cellular studies of the pathogenesis of this novel coronavirus are still in the early stages of research; however, based on similarities of SARS-CoV-2 to other coronaviruses, it can be hypothesized that the NF-κB, cytokine regulation, ERK, and TNF-α signaling pathways are the likely causes of inflammation at the onset of COVID-19. Several drugs have been prescribed and used to alleviate the adverse effects of these inflammatory cellular signaling pathways, and these might be beneficial for developing novel therapeutic modalities against COVID-19. In this review, we briefly summarize alterations of cellular signaling pathways that are associated with coronavirus infection, particularly SARS-CoV and MERS-CoV, and tabulate the therapeutic agents that are currently approved for treating other human diseases.

Protein Tyrosine Phosphatase SHP2 Suppresses Host Innate Immunity against Influenza A Virus by Regulating EGFR-Mediated Signaling

Influenza A virus (IAV) is a highly contagious pathogen, causing acute respiratory illnesses in human beings and animals and frequently giving rise to epidemic outbreaks. Evasion by IAV of host immunity facilitates viral replication and spread, which can be initiated through various mechanisms, including epidermal growth factor receptor (EGFR) activation. However, how EGFR mediates the suppression of antiviral systems remains unclear. Here, we examined host innate immune responses and their relevant signaling to EGFR upon IAV infection. IAV was found to induce the phosphorylation of EGFR and extracellular signal-regulated kinase (ERK) at an early stage of infection. Inhibition of EGFR or ERK suppressed the viral replication but increased the expression of type I and type III interferons (IFNs) and interferon-stimulated genes (ISGs), supporting the idea that IAV escapes from antiviral innate immunity by activating EGFR/ERK signaling. Meanwhile, IAV infection also induced the activation of Src homology region 2-containing protein tyrosine phosphatase 2 (SHP2). Pharmacological inhibition or small interfering RNA (siRNA)-based silencing of SHP2 enhanced the IFN-dependent antiviral activity and reduced virion production. Furthermore, knockdown of SHP2 attenuated the EGFR-mediated ERK phosphorylation triggered by viral infection or EGF stimulation. Conversely, ectopic expression of constitutively active SHP2 noticeably promoted ERK activation and viral replication, concomitant with diminished immune function. Altogether, the results indicate that SHP2 is crucial for IAV-induced activation of the EGFR/ERK pathway to suppress host antiviral responses.IMPORTANCE Viral immune evasion is the most important strategy whereby viruses evolve for their survival. This work shows that influenza A virus (IAV) suppressed the antiviral innate immunity through downregulation of IFNs and ISGs by activating EGFR/ERK signaling. Meanwhile, IAV also induced the activation of protein tyrosine phosphatase SHP2, which was found to be responsible for modulating the EGFR-mediated ERK activity and subsequent antiviral effectiveness both in vitro and in vivo The results suggest that SHP2 is a key signal transducer between EGFR and ERK and plays a crucial role in suppressing host innate immunity during IAV infection. The finding enhances our understanding of influenza immune evasion and provides a new therapeutic approach to viral infection.

Severe respiratory syncytial virus disease in preterm infants: a case of innate immaturity

Respiratory syncytial virus (RSV) is the most common viral pathogen associated with acute lower respiratory tract infection (LRTI) in children under 5 years of age. Severe RSV disease is associated with the development of chronic respiratory complications such as recurrent wheezing and asthma. A common risk factor for developing severe RSV disease is premature gestation and this is largely due to an immature innate immune system. This increases susceptibility to RSV since the innate immune system is less able to protect against pathogens at a time when adaptive immunity has not fully developed. This review focuses on comparing different aspects of innate immunity between preterm and term infants to better understand why preterm infants are more susceptible to severe RSV disease. Identifying early life innate immune biomarkers associated with the development of severe RSV disease, and understanding how these compare between preterm and term infants, remains a critically important question that would aid the development of interventions to reduce the burden of disease in this vulnerable population.

Interferon regulatory factor 1 (IRF1) and anti-pathogen innate immune responses

The eponymous member of the interferon regulatory factor (IRF) family, IRF1, was originally identified as a nuclear factor that binds and activates the promoters of type I interferon genes. However, subsequent studies using genetic knockouts or RNAi-mediated depletion of IRF1 provide a much broader view, linking IRF1 to a wide range of functions in protection against invading pathogens. Conserved throughout vertebrate evolution, IRF1 has been shown in recent years to mediate constitutive as well as inducible host defenses against a variety of viruses. Fine-tuning of these ancient IRF1-mediated host defenses, and countering strategies by pathogens to disarm IRF1, play crucial roles in pathogenesis and determining the outcome of infection.

Impaired airway epithelial cell wound-healing capacity is associated with airway remodelling following RSV infection in severe preschool wheeze

BACKGROUND

Respiratory syncytial virus (RSV) causes exacerbations of asthma and preschool wheeze (PSW). However, the anti-viral and repair responses of the bronchial epithelium in children with severe therapy-resistant asthma (STRA) and PSW are poorly understood.

METHODS

Children with STRA (age 12 [6-16] years), PSW (age 2 [1-5] years) and non-asthmatic controls (age 7 [2-14] years) underwent bronchoscopy with endobronchial brushings and biopsies. Anti-viral, wound injury responses were quantified in biopsies and primary bronchial epithelial cells (PBECs) in response to RSV, poly(I:C), house dust mite (HDM) or IL-33 using RT-qPCR, Luminex and live cell imaging. Collagen deposition and tissue expression of epithelial growth factor receptor (EGFR), IL-33 and receptor ST2 were investigated in bronchial biopsies.

RESULTS

PBECs from STRA and PSW had increased TLR3 gene expression and increased secretion of anti-viral and pro-inflammatory cytokines (IFN-γ, IL-6 and IL-13) in response to RSV compared to controls. Exposure of PBECs to concomitant TLR3 agonist poly(I:C) and HDM resulted in a significant reduction in epithelial cell proliferation in PSW compared to controls. Wound-healing was also impaired in PSW compared to controls at baseline and following IL-33 stimulation. In addition, tissue EGFR expression was significantly reduced in PSW and correlated with collagen deposition in endobronchial biopsies.

CONCLUSIONS

Despite increased anti-viral responses, preschool children with severe wheeze had impaired airway epithelial proliferative responses following damage. This might be connected to the low expression of EGFR in PSW which may affect epithelial function and contribute to asthma pathogenesis.