Human Metapneumovirus Impairs Apoptosis of Nasal Epithelial Cells in Asthma via HSP70

Drug screening identified that handelin inhibits feline calicivirus infection by inhibiting HSP70 expression in vitro

Feline calicivirus (FCV) is considered one of the major pathogens of cats worldwide and causes upper respiratory tract disease in all cats. In some cats, infection is by a highly virulent strain of FCV (vs.-FCV), which can cause severe and fatal systemic disease symptoms. At present, few antiviral drugs are approved for clinical treatment against FCV. Therefore, there is an imminent need for effective FCV antiviral agents. Here, we used observed a cytopathic effect (CPE) assay to screen 1746 traditional Chinese medicine monomer compounds and found one that can effectively inhibit FCV replication, namely, handelin, with an effective concentration (EC50) value of approximately 2.5 µM. Further study showed that handelin inhibits FCV replication via interference with heat shock protein 70 (HSP70), which is a crucial host factor and plays a positive role in regulating viral replication. Moreover, handelin and HSP70 inhibitors have broad-spectrum antiviral activity. These findings indicate that handelin is a potential candidate for the treatment of FCV infection and that HSP70 may be an important drug target.

MLKL Regulates Rapid Cell Death-independent HMGB1 Release in RSV Infected Airway Epithelial Cells

Respiratory syncytial virus (RSV)-induced bronchiolitis is a significant contributor to infant morbidity and mortality. Previously, we identified that necroptosis, a pro-inflammatory form of cell death mediated by receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and RIPK3, and mixed lineage kinase domain like protein (MLKL), occurs in RSV-infected human airway epithelial cells (hAECs), mediating the release of the alarmin high mobility group box 1 (HMGB1). Here, we show that RSV infection of hAECs induces the biphasic release of HMGB1 at 6 (“early”) and 24 (“late”) hours post infection (hpi). The early phase of HMGB1 release at 6 hpi is cell death-independent, however, this release is nonetheless attenuated by inhibition of MLKL (primarily associated with necroptosis). The early release of HMGB1 promotes the late phase of HMGB1 release via the activation of RAGE (receptor for advanced glycation endproducts) and occurs with cell death. Treatment of hAECS with exogenous HMGB1 combined with a pan-caspase inhibitor induces hAEC necroptosis, and is attenuated by the RAGE antagonist, FPS-ZM1. Together, these findings demonstrate that RSV infection of hAECs leads to the early release of HMGB1, followed by a paracrine feed-forward amplification loop that further increases HMGB1 levels and promotes cell death. As the inhibition of MLKL or targeting of HMGB1/RAGE pathway attenuates the release of pro-inflammatory HMGB1 and decreases viral load, this suggests that the pharmacological targeting of these pathways may be of benefit for the treatment of severe RSV bronchiolitis.

Impact of Therapeutics on Unified Immunity During Allergic Asthma and Respiratory Infections

Asthma is a common chronic respiratory disease that affects millions of people worldwide. Patients with allergic asthma, the most prevalent asthma endotype, are widely considered to possess a defective immune response against some respiratory infectious agents, including viruses, bacteria and fungi. Furthermore, respiratory pathogens are associated with asthma development and exacerbations. However, growing data suggest that the immune milieu in allergic asthma may be beneficial during certain respiratory infections. Immunomodulatory asthma treatments, although beneficial, should then be carefully prescribed to avoid misuse and overuse as they can also alter the host microbiome. In this review, we summarize and discuss recent evidence of the correlations between allergic asthma and the most significant respiratory infectious agents that have a role in asthma pathogenesis. We also discuss the implications of current asthma therapeutics beyond symptom prevention.

COPD Is Associated with Elevated IFN-β Production by Bronchial Epithelial Cells Infected with RSV or hMPV

IFN treatment may be a viable option for treating COPD exacerbations based on evidence of IFN deficiency in COPD. However, in vitro studies have used primarily influenza and rhinoviruses to investigate IFN responses. This study aims to investigate the susceptibility to infection and IFN response of primary bronchial epithelial cells (BECs) from COPD donors to infection with RSV and hMPV. BECs from five COPD and five healthy donors were used to establish both submerged monolayer and well-differentiated (WD) cultures. Two isolates of both RSV and hMPV were used to infect cells. COPD was not associated with elevated susceptibility to infection and there was no evidence of an intrinsic defect in IFN production in either cell model to either virus. Conversely, COPD was associated with significantly elevated IFN-β production in response to both viruses in both cell models. Only in WD-BECs infected with RSV was elevated IFN-β associated with reduced viral shedding. The role of elevated epithelial cell IFN-β production in the pathogenesis of COPD is not clear and warrants further investigation. Viruses vary in the responses that they induce in BECs, and so conclusions regarding antiviral responses associated with disease cannot be made based on single viral infections.

A Comprehensive Study on the Antimicrobial Properties of Resveratrol as an Alternative Therapy

Resveratrol is a polyphenolic antioxidant whose possible health benefits include anticarcinogenic, antiaging, and antimicrobial properties that have gained significant attention. The compound is well accepted by individuals and has been commonly used as a nutraceutical in recent decades. Its widespread usage makes it essential to study as a single agent as well as in combination with traditional prescription antibiotics as regards to antimicrobial properties. Resveratrol demonstrates the action of antimicrobials against a remarkable bacterial diversity, viruses, and fungus. This report explains resveratrol as an all-natural antimicrobial representative. It may modify the bacterial virulence qualities resulting in decreased toxic substance production, biofilm inhibition, motility reduction, and quorum sensing disturbance. Moreover, in conjunction with standard antibiotics, resveratrol improves aminoglycoside efficacy versus Staphylococcus aureus, while it antagonizes the deadly function of fluoroquinolones against S. aureus and also Escherichia coli. The present study aimed to thoroughly review and study the antimicrobial potency of resveratrol, expected to help researchers pave the way for solving antimicrobial resistance.

From Submerged Cultures to 3D Cell Culture Models: Evolution of Nasal Epithelial Cells in Asthma Research and Virus Infection

Understanding the response to viral infection in the context of respiratory diseases is of significant importance. Recently, there has been more focus on the role of the nasal epithelium in disease modeling. Here, we provide an overview of different submerged, organotypic 3D and spheroid cell culture models of nasal epithelial cells, which were used to study asthma and allergy with a special focus on virus infection. In detail, this review summarizes the importance, benefits, and disadvantages of patient-derived cell culture models of nasal- and bronchial epithelial cells, including a comparison of these cell culture models and a discussion on why investigators should consider using nasal epithelial cells in their research. Exposure experiments, simple virus transduction analyses as well as genetic studies can be performed in these models, which may provide first insights into the complexity of molecular signatures and may open new doors for drug discovery and biomarker research.

The Protective Effects of Helicobacter pylori Infection on Allergic Asthma

As an ancient Gram-negative bacterium, Helicobacter pylori has settled in human stomach. Eradicating H. pylori increases the morbidities of asthma and other allergic diseases. Therefore, H. pylori might play a protective role against asthma. The "disappearing microbiota" hypothesis suggests that the absence of certain types of the ancestral microbiota could change the development of immunology, metabolism, and cognitive ability in our early life, contributing to the development of some diseases. And the Hygiene Hypothesis links early environmental and microbial exposure to the prevalence of atopic allergies and asthma. Exposure to the environment and microbes can influence the growing immune system and protect subsequent immune-mediated diseases. H. pylori can inhibit allergic asthma by regulating the ratio of helper T cells 1/2 (Th1/Th2), Th17/regulatory T cells (Tregs), etc. H. pylori can also target dendritic cells to promote immune tolerance and enhance the protective effect on allergic asthma, and this effect relies on highly suppressed Tregs. The remote regulation of lung immune function by H. pylori is consistent with the gut-lung axis theory. Perhaps, H. pylori also protects against asthma by altering levels of stomach hormones, affecting the autonomic nervous system and lowering the expression of heat shock protein 70. Therapeutic products from H. pylori may be used to prevent and treat asthma. This paper reviews the possible protective influence of H. pylori on allergic asthma and the possible application of H. pylori in treating asthma.

Respiratory Syncytial Virus Infection Promotes Necroptosis and HMGB1 Release by Airway Epithelial Cells

Rationale: Respiratory syncytial virus (RSV) bronchiolitis causes significant infant mortality. Bronchiolitis is characterized by airway epithelial cell (AEC) death; however, the mode of death remains unknown.Objectives: To determine whether necroptosis contributes to RSV bronchiolitis pathogenesis via HMGB1 (high mobility group box 1) release.Methods: Nasopharyngeal samples were collected from children presenting to the hospital with acute respiratory infection. Primary human AECs and neonatal mice were inoculated with RSV and murine Pneumovirus, respectively. Necroptosis was determined via viability assays and immunohistochemistry for RIPK1 (receptor-interacting protein kinase-1), MLKL (mixed lineage kinase domain-like pseudokinase) protein, and caspase-3. Necroptosis was blocked using pharmacological inhibitors and RIPK1 kinase-dead knockin mice.Measurements and Main Results: HMGB1 levels were elevated in nasopharyngeal samples of children with acute RSV infection. RSV-induced epithelial cell death was associated with increased phosphorylated RIPK1 and phosphorylated MLKL but not active caspase-3 expression. Inhibition of RIPK1 or MLKL attenuated RSV-induced HMGB1 translocation and release, and lowered viral load. MLKL inhibition increased active caspase-3 expression in a caspase-8/9-dependent manner. In susceptible mice, Pneumovirus infection upregulated RIPK1 and MLKL expression in the airway epithelium at 8 to 10 days after infection, coinciding with AEC sloughing, HMGB1 release, and neutrophilic inflammation. Genetic or pharmacological inhibition of RIPK1 or MLKL attenuated these pathologies, lowered viral load, and prevented type 2 inflammation and airway remodeling. Necroptosis inhibition in early life ameliorated asthma progression induced by viral or allergen challenge in later life.Conclusions: Pneumovirus infection induces AEC necroptosis. Inhibition of necroptosis may be a viable strategy to limit the severity of viral bronchiolitis and break its nexus with asthma.

PGD2/DP2 receptor activation promotes severe viral bronchiolitis by suppressing IFN- production

Prostaglandin D2 (PGD2) signals through PGD2 receptor 2 (DP2, also known as CRTH2) on type 2 effector cells to promote asthma pathogenesis; however, little is known about its role during respiratory syncytial virus (RSV) bronchiolitis, a major risk factor for asthma development. We show that RSV infection up-regulated hematopoietic prostaglandin D synthase expression and increased PGD2 release by cultured human primary airway epithelial cells (AECs). Moreover, PGD2 production was elevated in nasopharyngeal samples from young infants hospitalized with RSV bronchiolitis compared to healthy controls. In a neonatal mouse model of severe viral bronchiolitis, DP2 antagonism decreased viral load, immunopathology, and morbidity and ablated the predisposition for subsequent asthma onset in later life. This protective response was abolished upon dual DP1/DP2 antagonism and replicated with a specific DP1 agonist. Rather than mediating an effect via type 2 inflammation, the beneficial effects of DP2 blockade or DP1 agonism were associated with increased interferon-λ (IFN-λ) [interleukin-28A/B (IL-28A/B)] expression and were lost upon IL-28A neutralization. In RSV-infected AEC cultures, DP1 activation up-regulated IFN-λ production, which, in turn, increased IFN-stimulated gene expression, accelerating viral clearance. Our findings suggest that DP2 antagonists or DP1 agonists may be useful antivirals for the treatment of viral bronchiolitis and possibly as primary preventatives for asthma.

Heat shock protein 70 is a positive regulator of airway inflammation and goblet cell hyperplasia in a mouse model of allergic airway inflammation

Heat shock proteins (Hsps) are highly conserved molecular chaperones that are ubiquitously expressed in all species to aid the solubilization of misfolded proteins, protein degradation, and transport. Elevated levels of Hsp70 have been found in the sputum, serum, and bronchoalveolar lavage (BAL) fluid of asthma patients and are known to correlate with disease severity. However, the function of Hsp70 in allergic airway inflammation has remained largely unknown. This study aimed to determine the role of Hsp70 in airway inflammation and remodeling using a mouse model of allergic airway inflammation. WT and Hsp70 double-knockout (Hsp70.1/.3^-/-) mice were sensitized and challenged intratracheally with Schistosoma mansoni soluble egg antigens (SEAs) to induce robust Th2 responses and airway inflammation in the lungs. The lack of Hsp70 resulted in a significant reduction in airway inflammation, goblet cell hyperplasia, and Th2 cytokine production, including IL-4, IL-5, and IL-13. An analysis of the BAL fluid suggested that Hsp70 is critically required for eosinophilic infiltration, collagen accumulation, and Th2 cytokine production in allergic airways. Furthermore, our bone marrow (BM) transfer studies show that SEA-induced airway inflammation, goblet cell hyperplasia, and Th2 cytokine production were attenuated in WT mice that were reconstituted with Hsp70-deficient BM, but these effects were not attenuated in Hsp70-deficient mice that were reconstituted with WT BM. Together, these studies identify a pathogenic role for Hsp70 in hematopoietic cells during allergic airway inflammation; this illustrates the potential utility of targeting Hsp70 to alleviate allergen-induced Th2 cytokines, goblet cell hyperplasia, and airway inflammation.

Desmoglein 3 gene mediates epidermal growth factor/epidermal growth factor receptor signaling pathway involved in inflammatory response and immune function of anaphylactic rhinitis

OBJECTIVE

To investigate the effects of desmoglein 3 (DSG3) gene mediating epidermal growth factor/epidermal growth factor receptor (EGF/EGFR) signaling pathway on inflammatory response and immune function of anaphylactic rhinitis (AR).

METHODS

Ten of the seventy male BALB/c mice were randomly selected as the normal control group, and the remaining 60 were used to construct the AR mice model. AR model mice were divided into 6 groups: model group (instilled with 5 μL saline), empty vector group (instilled with 5 μL of liposome and empty vector mixture), siRNA-DSG3 group (instilled with 5 μL of liposome and siRNA-DSG3 carrier mixture), AG1478 group (instilled with 5 μL of EGF/EGFR inhibitor AG1478), siRNA-DSG3+AG1478 group (instilled with 5 μL of liposome and siRNA-DSG3 carrier and EGF/EGFR inhibitor AG1478 mixture) and oe-DSG3 group, 10 in each group. After taking serum, each group of mice was sacrificed to get nasal mucosa tissues. HE staining was used to observe the pathological changes of nasal mucosa tissues in each group. The expression levels of DSG3, EGF and EGFR in nasal mucosa tissues of mice in each group were detected by qRT-PCR and western blot methods respectively. TUNEL staining was used to observe the apoptosis of nasal mucosa cells in mice. The expression of IgE, INF-γ, TNF-α, IL-2, IL-4 and IL-6 in serum of mice was determined by ELISA method. The immune adhesion function of red blood cells was detected by complement sensitization yeast hemagglutination method.

RESULTS

All the mice with AR showed different degrees of nasal mucosa injury and inflammatory cell infiltration, and silencing DSG3 or inhibiting the activity of EGF signaling pathway could alleviate the nasal mucosa injury. Compared with control group, the INF-γ and IL-2 levels of serum in AR model mice were significantly decreased; IgE, TNF-α, IL-4 and IL-6 levels were significantly increased (all P < 0.05); the mRNA expression levels and protein levels of DSG3, EGF and EGFR were significantly increased (all P < 0.05); C₃b receptor rosette rate and Ic rosette rate were significantly decreased (all P < 0.05). Detected by ELISA method, the expression levels of IgE, TNF-α, IL-4 and IL-6 were increased, while the expression levels of INF-γ and IL-2 were decreased after DSG3 silencing or using AG1478. Detected by qRT-PCR and western blot methods, the expression of DSG3, EGF and EGFR did decrease after DSG3 silencing. There was no significant difference in the EGF and EGFR expression between DSG3 silencing and using AG1478, and the expression decreased even more under the double effect. The mRNA and protein expression levels of DSG3, EGF and EGFR in the nasal mucosa tissues of mice with overexpression of DSG3 plasmid were significantly higher than those of normal mice (all P < 0.05).

CONCLUSION

Silencing DSG3 gene can inhibit the activation of EGF signaling pathway, alleviate the inflammation of AR nasal mucosa, and enhance red blood cells immune adherence function.

MEK inhibition drives anti-viral defence in RV but not RSV challenged human airway epithelial cells through AKT/p70S6K/4E-BP1 signalling

BACKGROUND

The airway epithelium is a major target tissue in respiratory infections, and its antiviral response is mainly orchestrated by the interferon regulatory factor-3 (IRF3), which subsequently induces type I (β) and III (λ) interferon (IFN) signalling. Dual specificity mitogen-activated protein kinase kinase (MEK) pathway contributes to epithelial defence, but its role in the regulation of IFN response in human primary airway epithelial cells (AECs) is not fully understood. Here, we studied the impact of a small-molecule inhibitor (MEKi) on the IFN response following challenge with two major respiratory viruses rhinovirus (RV2) and respiratory syncytial virus (RSVA2) and a TLR3 agonist, poly(I:C).

METHODS

The impact of MEKi on viral load and IFN response was evaluated in primary AECs with or without a neutralising antibody against IFN-β. Quantification of viral load was determined by live virus assay and absolute quantification using qRT-PCR. Secretion of cytokines was determined by AlphaLISA/ELISA and expression of interferon-stimulated genes (ISGs) was examined by qRT-PCR and immunoblotting. A poly(I:C) model was also used to further understand the molecular mechanism by which MEK controls IFN response. AlphaLISA, siRNA-interference, immunoblotting, and confocal microscopy was used to investigate the effect of MEKi on IRF3 activation and signalling. The impact of MEKi on ERK and AKT signalling was evaluated by immunoblotting and AlphaLISA.

RESULTS

Here, we report that pharmacological inhibition of MEK pathway augments IRF3-driven type I and III IFN response in primary human AECs. MEKi induced activation of PI3K-AKT pathway, which was associated with phosphorylation/inactivation of the translational repressor 4E-BP1 and activation of the protein synthesis regulator p70 S6 kinase, two critical translational effectors. Elevated IFN-β response due to MEKi was also attributed to decreased STAT3 activation, which consequently dampened expression of the transcriptional repressor of IFNB1 gene, PRDI-BF1. Augmented IFN response translated into inhibition of rhinovirus 2 replication in primary AECs but not respiratory syncytial virus A2.

CONCLUSIONS

Our findings unveil MEK as a key molecular mechanism by which rhinovirus dampens the epithelial cell's antiviral response. Our study provides a better understanding of the role of signalling pathways in shaping the antiviral response and suggests the use of MEK inhibitors in anti-viral therapy against RV.

Increased susceptibility of airway epithelial cells from ataxia-telangiectasia to S. pneumoniae infection due to oxidative damage and impaired innate immunity

Respiratory disease is a major cause of morbidity and mortality in patients with ataxia-telangiectasia (A-T) who are prone to recurrent sinopulmonary infections, bronchiectasis, pulmonary fibrosis, and pulmonary failure. Upper airway infections are common in patients and S. pneumoniae is associated with these infections. We demonstrate here that the upper airway microbiome in patients with A-T is different from that to healthy controls, with S. pneumoniae detected largely in patients only. Patient-specific airway epithelial cells and differentiated air-liquid interface cultures derived from these were hypersensitive to infection which was at least in part due to oxidative damage since it was partially reversed by catalase. We also observed increased levels of the pro-inflammatory cytokines IL-8 and TNF-α (inflammasome-independent) and a decreased level of the inflammasome-dependent cytokine IL-β in patient cells. Further investigation revealed that the ASC-Caspase 1 signalling pathway was defective in A-T airway epithelial cells. These data suggest that the heightened susceptibility of these cells to S. pneumoniae infection is due to both increased oxidative damage and a defect in inflammasome activation, and has implications for lung disease in these patients.

Chaperoning the Mononegavirales: Current Knowledge and Future Directions

The order Mononegavirales harbors numerous viruses of significant relevance to human health, including both established and emerging infections. Currently, vaccines are only available for a small subset of these viruses, and antiviral therapies remain limited. Being obligate cellular parasites, viruses must utilize the cellular machinery for their replication and spread. Therefore, targeting cellular pathways used by viruses can provide novel therapeutic approaches. One of the key challenges confronted by both hosts and viruses alike is the successful folding and maturation of proteins. In cells, this task is faced by cellular molecular chaperones, a group of conserved and abundant proteins that oversee protein folding and help maintain protein homeostasis. In this review, we summarize the current knowledge of how the Mononegavirales interact with cellular chaperones, highlight key gaps in our knowledge, and discuss the potential of chaperone inhibitors as antivirals.

Viral infections in allergy and immunology: How allergic inflammation influences viral infections and illness

Viral respiratory tract infections are associated with asthma inception in early life and asthma exacerbations in older children and adults. Although how viruses influence asthma inception is poorly understood, much research has focused on the host response to respiratory viruses and how viruses can promote; or how the host response is affected by subsequent allergen sensitization and exposure. This review focuses on the innate interferon-mediated host response to respiratory viruses and discusses and summarizes the available evidence that this response is impaired or suboptimal. In addition, the ability of respiratory viruses to act in a synergistic or additive manner with T_H2 pathways will be discussed. In this review we argue that these 2 outcomes are likely linked and discuss the available evidence that shows reciprocal negative regulation between innate interferons and T_H2 mediators. With the renewed interest in anti-T_H2 biologics, we propose a rationale for why they are particularly successful in controlling asthma exacerbations and suggest ways in which future clinical studies could be used to find direct evidence for this hypothesis.

Human Metapneumovirus Infection in Chronic Obstructive Pulmonary Disease: Impact of Glucocorticosteroids and Interferon

Background

Human metapneumovirus (hMPV) infection is implicated in exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Research into the pathogenesis of infection is restricted to animal models, and information about hMPV replication and inflammatory and immune responses in human disease is limited.

Methods

Human primary bronchial epithelial cells (PBECs) from healthy and asthmatic subjects and those with COPD were infected with hMPV, with or without glucocorticosteroid (GCS) exposure. Viral replication, inflammatory and immune responses, and apoptosis were analyzed. We also determined whether adjuvant interferon (IFN) can blunt hMPV infection in vitro and in a murine model.

Results

hMPV infected human PBECs and viral replication was enhanced in cells from patients with COPD. The virus induced gene expression of IFN-stimulated gene 56 (ISG56) and IFN-β, as well as IFN-γ-inducible protein 10 (IP-10) and regulated on activation, normal T cell expressed and secreted (RANTES), and more so in cells from patients with COPD. GCS exposure enhanced hMPV replication despite increased IFN expression. Augmented virus replication associated with GCS was mediated by reduced apoptosis via induction of antiapoptotic genes. Adjuvant IFN treatment suppressed hMPV replication in PBECs and reduced hMPV viral titers and inflammation in vivo.

Conclusions

hMPV infects human PBECs, eliciting innate and inflammatory responses. Replication is enhanced by GCS and adjuvant IFN is an effective treatment, restricting virus replication and proinflammatory consequences of hMPV infections.