Relationship of upper and lower airway cytokines to outcome of experimental rhinovirus infection

The association between COVID-19 vaccine/infection and new-onset asthma in children - based on the global TriNetX database

INTRODUCTION

The COVID-19 pandemic has underscored the importance of its potential long-term health effects, including its link to new-onset asthma in children. Asthma significantly impacts children's health, causing adverse outcomes and increased absenteeism. Emerging evidence suggests a potential association between COVID-19 infection and higher rates of new-onset asthma in adults, raising concerns about its impact on children's respiratory health.

METHODS

A retrospective cohort study design was employed, using electronic medical records from the TriNetX database, covering January 1, 2021, to December 31, 2022. Two cohorts of children aged 5 to 18 who underwent SARS-CoV-2 RT-PCR testing were analyzed: unvaccinated children with and without COVID-19 infection, and vaccinated children with and without infection. Propensity score matching was used to mitigate selection bias, and hazard ratio (HR) and 95% CI were calculated to assess the risk of new-onset asthma.

RESULTS

Our study found a significantly higher incidence of new-onset asthma in COVID-19 infected children compared to uninfected children, regardless of vaccination status. In Cohort 1, 4.7% of COVID-19 infected children without vaccination developed new-onset asthma, versus 2.0% in their non-COVID-19 counterparts within a year (HR = 2.26; 95% CI = 2.158-2.367). For Cohort 2, COVID-19 infected children with vaccination showed an 8.3% incidence of new-onset asthma, higher than the 3.1% in those not infected (HR = 2.745; 95% CI = 2.521-2.99). Subgroup analyses further identified higher risks in males, children aged 5-12 years, and Black or African American children. Sensitivity analyses confirmed the reliability of these findings.

CONCLUSION

The study highlights a strong link between COVID-19 infection and an increased risk of new-onset asthma in children, which is even more marked in those vaccinated. This emphasizes the critical need for ongoing monitoring and customized healthcare strategies to mitigate the long-term respiratory impacts of COVID-19 in children, advocating for thorough strategies to manage and prevent asthma amidst the pandemic.

Airway-delivered short-chain fatty acid acetate boosts antiviral immunity during rhinovirus infection

BACKGROUND

Microbiota are recognized to play a major role in regulation of immunity through release of immunomodulatory metabolites such as short-chain fatty acids (SCFAs). Rhinoviruses (RVs) induce upper respiratory tract illnesses and precipitate exacerbations of asthma and chronic obstructive pulmonary disease through poorly understood mechanisms. Local interactions between SCFAs and antiviral immune responses in the respiratory tract have not been previously investigated.

OBJECTIVE

We sought to investigate whether pulmonary metabolite manipulation through lung-delivered administration of SCFAs can modulate antiviral immunity to RV infection.

METHODS

We studied the effects of intranasal administration of the SCFAs acetate, butyrate, and propionate on basal expression of antiviral signatures, and of acetate in a mouse model of RV infection and in RV-infected lung epithelial cell lines. We additionally assessed the effects of acetate, butyrate, and propionate on RV infection in differentiated human primary bronchial epithelial cells.

RESULTS

Intranasal acetate administration induced basal upregulation of IFN-β, an effect not observed with other SCFAs. Butyrate induced RIG-I expression. Intranasal acetate treatment of mice increased interferon-stimulated gene and IFN-λ expression during RV infection and reduced lung virus loads at 8 hours postinfection. Acetate ameliorated virus-induced proinflammatory responses with attenuated pulmonary mucin and IL-6 expression observed at day 4 and 6 postinfection. This interferon-enhancing effect of acetate was confirmed in human bronchial and alveolar epithelial cell lines. In differentiated primary bronchial epithelial cells, butyrate treatment better modulated IFN-β and IFN-λ gene expression during RV infection.

CONCLUSIONS

SCFAs augment antiviral immunity and reduce virus load and proinflammatory responses during RV infection.

Rhinovirus Infection and Virus-Induced Asthma

While the aetiology of asthma is unclear, the onset and/or exacerbation of asthma may be associated with respiratory infections. Virus-induced asthma is also known as virus-associated/triggered asthma, and the reported main causative agent is rhinovirus (RV). Understanding the relationship between viral infections and asthma may overcome the gaps in deferential immunity between viral infections and allergies. Moreover, understanding the complicated cytokine networks involved in RV infection may be necessary. Therefore, the complexity of RV-induced asthma is not only owing to the response of airway and immune cells against viral infection, but also to allergic immune responses caused by the wide variety of cytokines produced by these cells. To better understand RV-induced asthma, it is necessary to elucidate the nature RV infections and the corresponding host defence mechanisms. In this review, we attempt to organise the complexity of RV-induced asthma to make it easily understandable for readers.

Transcriptomics of rhinovirus persistence reveals sustained expression of RIG-I and interferon-stimulated genes in nasal epithelial cells in vitro

BACKGROUND

Human rhinoviruses (HRVs) are frequently associated with asthma exacerbations, and have been found in the airways of asthmatic patients. While HRV-induced acute infection is well-documented, it is less clear whether the nasal epithelium sustains prolonged HRV infections along with the associated activation of host immune responses.

OBJECTIVE

To investigate sustainably regulated host responses of human nasal epithelial cells (hNECs) during HRV persistence.

METHODS

Using a time-course study, HRV16 persistence and viral replication dynamics were established using an in vitro infection model of hNECs. RNA sequencing was performed on hNECs in the early and late stages of infection at 3 and 14 days post-infection (dpi), respectively. The functional enrichment of differentially expressed genes (DEGs) was evaluated using gene ontology (GO) and Ingenuity pathway analysis.

RESULTS

HRV RNA and protein expression persisted throughout prolonged infections, even after decreased production of infectious virus progeny. GO analysis of unique DEGs indicated altered regulation of pathways related to ciliary function and airway remodeling at 3 dpi and serine-type endopeptidase activity at 14 dpi. The functional enrichment of shared DEGs between the two time-points was related to interferon (IFN) and cytoplasmic pattern recognition receptor (PRR) signaling pathways. Validation of the sustained regulation of candidate genes confirmed the persistent expression of RIG-I and revealed its close co-regulation with interferon-stimulated genes (ISGs) during HRV persistence.

CONCLUSIONS

The persistence of HRV RNA does not necessarily indicate an active infection during prolonged infection. The sustained expression of RIG-I and ISGs in response to viral RNA persistence highlights the importance of assessing how immune-activating host factors can change during active HRV infection and the immune regulation that persists thereafter.

Airway mucins promote immunopathology in virus-exacerbated chronic obstructive pulmonary disease

The respiratory tract surface is protected from inhaled pathogens by a secreted layer of mucus rich in mucin glycoproteins. Abnormal mucus accumulation is a cardinal feature of chronic respiratory diseases, but the relationship between mucus and pathogens during exacerbations is poorly understood. We identified elevations in airway mucin 5AC (MUC5AC) and MUC5B concentrations during spontaneous and experimentally induced chronic obstructive pulmonary disease (COPD) exacerbations. MUC5AC was more sensitive to changes in expression during exacerbation and was therefore more predictably associated with viral load, inflammation, symptom severity, decrements in lung function, and secondary bacterial infections. MUC5AC was functionally related to inflammation, as Muc5ac-deficient (Muc5ac-/-) mice had attenuated RV-induced (RV-induced) airway inflammation, and exogenous MUC5AC glycoprotein administration augmented inflammatory responses and increased the release of extracellular adenosine triphosphate (ATP) in mice and human airway epithelial cell cultures. Hydrolysis of ATP suppressed MUC5AC augmentation of RV-induced inflammation in mice. Therapeutic suppression of mucin production using an EGFR antagonist ameliorated immunopathology in a mouse COPD exacerbation model. The coordinated virus induction of MUC5AC and MUC5B expression suggests that non-Th2 mechanisms trigger mucin hypersecretion during exacerbations. Our data identified a proinflammatory role for MUC5AC during viral infection and suggest that MUC5AC inhibition may ameliorate COPD exacerbations.

Unraveling the Relationship of Asthma and COVID-19

Viral infections are one of the main causes of asthma exacerbations. During the COVID-19 era, concerns regarding the relationship of SARS-CoV2 with asthma have been raised. The concerns are both for COVID severity and asthma exacerbations. Many studies on COVID-19 epidemiology and comorbidities have assessed whether asthma represents a risk factor for SARS-CoV2 infection and/or more severe course of the disease. This review covers the current evidence on the prevalence of asthma in COVID-19 and its association with susceptibility to and severity of SARS-CoV2 infection. It will examine the possible role of underlying asthma severity in COVID-19 related outcomes as well as the molecular mechanisms involved in the co-existence of these entities. The possible role of asthma inflammatory phenotypes will also be evaluated. Finally, the impact of asthma comorbidities and the implications of asthma medication on COVID-19 will be addressed.

Pulmonary Innate Lymphoid Cell Responses during Rhinovirus-induced Asthma Exacerbations In Vivo: A Clinical Trial

Rationale Type 2 innate lymphoid cells (ILC2s) are significant sources of type 2 cytokines, which are implicated in the pathogenesis of asthma and asthma exacerbations. The role of ILC2s in virus-induced asthma exacerbations is not well-characterized. Objectives To characterize pulmonary ILC responses following experimental rhinovirus challenge in patients with moderate asthma and healthy subjects. Methods Patients with moderate asthma and healthy subjects were inoculated with rhinovirus-16, and underwent bronchoscopy at baseline, day 3 and day 8 post-inoculation. Pulmonary ILC1s and ILC2s were quantified in bronchoalveolar lavage (BAL) using flow cytometry. The ratio of BAL ILC2:ILC1 was assessed to determine their relative contributions to the clinical and immune response to rhinovirus challenge. Measurements and Main Results At baseline, ILC2s were significantly higher in patients with asthma than healthy subjects. At day 8, ILC2s significantly increased from baseline in both groups, which was significantly higher in asthma than in healthy subjects (all comparisons P<0.05). In healthy subjects, ILC1s increased from baseline at day 3 (P=0.001), while in patients with asthma, ILC1s increased from baseline at day 8 (P=0.042). Patients with asthma had significantly higher ILC2:ILC1 ratios at baseline (P=0.024) and day 8 (P=0.005). Increased ILC2:ILC1 ratio in asthma correlated with clinical exacerbation severity and type 2 cytokines in nasal mucosal lining fluid. Conclusions An ILC2-predominant inflammatory profile in asthma was associated with increased severity and duration of rhinovirus infection compared with healthy subjects, supporting the potential role of ILC2s in the pathogenesis of virus-induced asthma exacerbations. Clinical trial registration available at www.clinicaltrials.gov, ID: NCT01773590.

Protection against neonatal respiratory viral infection via maternal treatment during pregnancy with the benign immune training agent OM-85

Objectives

Incomplete maturation of immune regulatory functions at birth is antecedent to the heightened risk for severe respiratory infections during infancy. Our forerunner animal model studies demonstrated that maternal treatment with the microbial‐derived immune training agent OM‐85 during pregnancy promotes accelerated postnatal maturation of mechanisms that regulate inflammatory processes in the offspring airways. Here, we aimed to provide proof of concept for a novel solution to reduce the burden and potential long‐term sequelae of severe early‐life respiratory viral infection through maternal oral treatment during pregnancy with OM‐85, already in widespread human clinical use.

Methods

In this study, we performed flow cytometry and targeted gene expression (RT‐qPCR) analysis on lungs from neonatal offspring whose mothers received oral OM‐85 treatment during pregnancy. We next determined whether neonatal offspring from OM‐85 treated mothers demonstrate enhanced protection against lethal lower respiratory infection with mouse‐adapted rhinovirus (vMC₀), and associated lung immune changes.

Results

Offspring from mothers treated with OM‐85 during pregnancy display accelerated postnatal seeding of lung myeloid populations demonstrating upregulation of function‐associated markers. Offspring from OM‐85 mothers additionally exhibit enhanced expression of TLR4/7 and the IL‐1β/NLRP3 inflammasome complex within the lung. These treatment effects were associated with enhanced capacity to clear an otherwise lethal respiratory viral infection during the neonatal period, with concomitant regulation of viral‐induced IFN response intensity.

Conclusion

These results demonstrate that maternal OM‐85 treatment protects offspring against lethal neonatal respiratory viral infection by accelerating development of innate immune mechanisms crucial for maintenance of local immune homeostasis in the face of pathogen challenge.

In Vitro Effects of 5-Lipoxygenase Pathway Inhibition on Rhinovirus-Associated Bronchial Epithelial Inflammation

Introduction

The leukotriene pathway may be implicated in the induction of virus-induced inflammation. Respiratory epithelial cells may express low levels of 5-lipoxygenase (5-LO) and release leukotrienes (LTs) C4, D4, and E4, upon exposure to viruses or other stimuli. Enhanced expression of 5-LO pathway proteins after rhinovirus (RV) infection has previously been described. We hypothesized that anti-leukotriene treatment of epithelial cells, with or without exposure to RV-infected peripheral blood mononuclear cells (PBMCs)-conditioned media, may inhibit RV-induced up-regulation of inflammatory cytokines.

Methods

PBMCs from a healthy donor were exposed to RV1B and supernatants were harvested at 48 h post infection. BEAS-2B cells were infected with RV, with or without conditioning with the PBMC supernatant. Treatment with anti-LT agents was performed either on both PBMCs and BEAS-2B or at the bronchial epithelial level only, with varying concentrations of montelukast (CysLT receptor antagonist) or MK-886 [FLAP(5-lipoxygenase-activating-protein) inhibitor]. Evaluation of the inflammatory cytokines IL-8, RANTES, IL-11, IL-6, and IP-10 was performed using ELISA.

Results

Our results show that anti-LT treatment of RV-infected bronchial epithelial cells suppresses epithelial RV-mediated cytokine production, independent of conditioning.

Conclusions

This observation may represent an indirect mode of action of the anti-leukotrienes in virus-induced asthma.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41030-021-00152-x.

Nasal interferon responses to community rhinovirus infections are similar in controls and children with asthma

BACKGROUND

Rhinovirus (RV) is the main cause of asthma exacerbations in children. Some studies reported that persons with asthma have attenuated interferon (IFN) responses to experimental RV infection compared with healthy individuals. However, responses to community-acquired RV infections in controls and children with asthma have not been compared.

OBJECTIVE

To evaluate nasal cytokine responses after natural RV infections in people with asthma and healthy children.

METHODS

We compared nasal cytokine expression among controls and children with asthma during healthy, virus-negative surveillance weeks and self-reported RV-positive sick weeks. A total of 14 controls and 21 patients with asthma were studied. Asthma disease severity was based on symptoms and medication use. Viral genome was detected by multiplex polymerase chain reaction. Nasal cytokine protein levels were determined by multiplex assays.

RESULTS

Two out of 47 surveillance weeks tested positive for RV, illustrating an asymptomatic infection rate of 5%. A total of 38 of 47 sick weeks (81%) tested positive for the respiratory virus. Of these, 33 (87%) were positive for RV. During well weeks, nasal interleukin 8 (IL-8), IL-12, and IL-1β levels were higher in children with asthma than controls. Compared with healthy virus-negative surveillance weeks, IL-8, IL-13, and interferon beta increased during colds only in patients with asthma. In both controls and children with asthma, the nasal levels of interferon gamma, interferon lambda-1, IL-1β, IL-8, and IL-10 increased during RV-positive sick weeks. During RV infection, IL-8, IL-1β, and tumor necrosis factor-α levels were strongly correlated.

CONCLUSION

In both controls and patients with asthma, natural RV infection results in robust type II and III IFN responses.

Natural Killer Cells and Host Defense Against Human Rhinoviruses Is Partially Dependent on Type I IFN Signaling

Rhinovirus (RV), the causative agent of the common cold, causes only mild upper respiratory tract infections in healthy individuals, but can cause longer lasting and more severe pulmonary infections in people with chronic lung diseases and in the setting of immune suppression or immune deficiency. RV-infected lung structural cells release type I interferon (IFN-I), initiating the immune response, leading to protection against viruses in conjunction with migratory immune cells. However, IFN-I release is deficient in some people with asthma. Innate immune cells, such as natural killer (NK) cells, are proposed to play major roles in the control of viral infections, and may contribute to exacerbations of chronic lung diseases, such as asthma. In this study, we characterized the NK cell response to RV infection using an in vitro model of infection in healthy individuals, and determined the extent to which IFN-I signaling mediates this response. The results indicate that RV stimulation in vitro induces NK cell activation in healthy donors, leading to degranulation and the release of cytotoxic mediators and cytokines. IFN-I signaling was partly responsible for NK cell activation and functional responses to RV. Overall, our findings suggest the involvement of NK cells in the control of RV infection in healthy individuals. Further understanding of NK cell regulation may deepen our understanding of the mechanisms that contribute to susceptibility to RV infections in asthma and other chronic lung diseases.

Role of Probiotics in Stimulating the Immune System in Viral Respiratory Tract Infections: A Narrative Review

Viral respiratory tract infection (RTI) is the most frequent cause of infectious illnesses including the common cold. Pharmacological solutions for treating or preventing viral RTIs are so far limited and thus several self-care products are available in the market. Some dietary supplements such as probiotics have been shown to modulate immune system function and their role in reducing the risk and the course of RTIs has been investigated extensively within the past decade. However, the mechanism of action and the efficacy of probiotics against viral RTIs remains unclear. We searched PubMed, Google Scholar, and Web of Knowledge for pre-clinical and clinical studies investigating the effect of probiotics on respiratory virus infections, immune response, and the course of upper and lower respiratory tract illness. The literature summarized in this narrative review points out that specific probiotic strains seem effective in pre-clinical models, through stimulating the immune system and inhibiting viral replication. Clinical studies indicate variable efficacy on upper respiratory illnesses and lack proof of diagnosed viral infections. However, meta-analyses of clinical studies indicate that probiotics could be beneficial in upper respiratory illnesses without specific etiology. Further studies aiming at discovering the mechanisms of action of probiotics and clinical efficacy are warranted.

Rhinovirus and Innate Immune Function of Airway Epithelium

Airway epithelial cells, which lines the respiratory mucosa is in direct contact with the environment. Airway epithelial cells are the primary target for rhinovirus and other inhaled pathogens. In response to rhinovirus infection, airway epithelial cells mount both pro-inflammatory responses and antiviral innate immune responses to clear the virus efficiently. Some of the antiviral responses include the expression of IFNs, endoplasmic reticulum stress induced unfolded protein response and autophagy. Airway epithelial cells also recruits other innate immune cells to establish antiviral state and resolve the inflammation in the lungs. In patients with chronic lung disease, these responses may be either defective or induced in excess leading to deficient clearing of virus and sustained inflammation. In this review, we will discuss the mechanisms underlying antiviral innate immunity and the dysregulation of some of these mechanisms in patients with chronic lung diseases.

Human TH1 and TH2 cells targeting rhinovirus and allergen coordinately promote allergic asthma

BACKGROUND

Allergic asthmatic subjects are uniquely susceptible to acute wheezing episodes provoked by rhinovirus. However, the underlying immune mechanisms and interaction between rhinovirus and allergy remain enigmatic, and current paradigms are controversial.

OBJECTIVE

We sought to perform a comprehensive analysis of type 1 and type 2 innate and adaptive responses in allergic asthmatic subjects infected with rhinovirus.

METHODS

Circulating virus-specific T_H1 cells and allergen-specific T_H2 cells were precisely monitored before and after rhinovirus challenge in allergic asthmatic subjects (total IgE, 133-4692 IU/mL; n = 28) and healthy nonallergic controls (n = 12) using peptide/MHCII tetramers. T cells were sampled for up to 11 weeks to capture steady-state and postinfection phases. T-cell responses were analyzed in parallel with 18 cytokines in the nose, upper and lower airway symptoms, and lung function. The influence of in vivo IgE blockade was also examined.

RESULTS

In uninfected asthmatic subjects, higher numbers of circulating virus-specific PD-1⁺ T_H1 cells, but not allergen-specific T_H2 cells, were linked to worse lung function. Rhinovirus infection induced an amplified antiviral T_H1 response in asthmatic subjects versus controls, with synchronized allergen-specific T_H2 expansion, and production of type 1 and 2 cytokines in the nose. In contrast, T_H2 responses were absent in infected asthmatic subjects who had normal lung function, and in those receiving anti-IgE. Across all subjects, early induction of a minimal set of nasal cytokines that discriminated high responders (G-CSF, IFN-γ, TNF-α) correlated with both egress of circulating virus-specific T_H1 cells and worse symptoms.

CONCLUSIONS

Rhinovirus induces robust T_H1 responses in allergic asthmatic subjects that may promote disease, even after the infection resolves.

Are rhinoviruses implicated in the pathogenesis of sinusitis and chronic rhinosinusitis exacerbations? A comprehensive review

BACKGROUND

Rhinovirus (RV) infections are the most common cause of viral upper respiratory infections (URIs), and in the majority of persons they are self-limiting. However, in others, viral URIs can progress to bacterial sinusitis and induce chronic rhinosinusitis (CRS) exacerbations.

METHODS

We conducted a comprehensive Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) review through April 2018 based on MEDLINE, EMBASE, Web of Science-Science Citation Index (SCI), and Conference Proceedings Citation Index- Science (CPCI-S) using keywords: RV, respiratory virus, sinusitis, and airway epithelial cells. The goal of this systematic review was to: (1) determine the prevalence between RV and CRS, (2) study the changes that occur after experimental RV inoculation, (3) investigate the pathophysiologic mechanisms by which RV induces sinonasal inflammation, and (4) explore the treatment options available for RV-associated sinusitis. Data regarding study design, research question, intervention, subjects, outcomes, and biases was extracted.

RESULTS

The initial search yielded 2395 unique abstracts, of which 614 were selected for full-text review; 147 were included in the final review. We determined that (1) the prevalence of RV infections is increased in those with CRS, (2) humans challenged in vivo with RV secrete local inflammatory mediators with radiographic mucosal thickening, (3) RV species RV-A and RV-C challenges in vitro to sinonasal epithelia produce robust cytokine responses and differential gene changes, and (4) no current therapies have produced consistent and significant resolution of disease.

CONCLUSION

RV infections are common in persons with CRS, and incite inflammatory reactions that may result in CRS exacerbations and progression of disease. Further studies assessing RV species, and the host-virome response are required to develop new strategies targeting RV-induced CRS.

Rhinovirus Attributes that Contribute to Asthma Development

Early-life wheezing-associated infections with human rhinovirus (HRV) are strongly associated with the inception of asthma. The immune system of immature mice and humans is skewed toward a type 2 cytokine response. Thus, HRV-infected 6-day-old mice but not adult mice develop augmented type 2 cytokine expression, eosinophilic inflammation, mucous metaplasia, and airway hyperresponsiveness. This asthma phenotype depends on interleukin (IL)-13-producing type 2 innate lymphoid cells, the expansion of which in turn depends on release of the innate cytokines IL-25, IL-33, and thymic stromal lymphopoietin from the airway epithelium. In humans, certain genetic variants may predispose to HRV-induced childhood asthma.

In vivo experimental models of infection and disease

Human and animal models continue to play a crucial role in research to understand host immunity to rhinovirus (RV) and identify disease mechanisms. Human models have provided direct evidence that RV infection is capable of exacerbating chronic respiratory diseases and identified immunological processes that correlate with clinical disease outcomes. Mice are the most commonly used nonhuman experimental RV infection model. Although semipermissive, under defined experimental conditions sufficient replication occurs to induce host immune responses that recapitulate immunity and disease during human infection. The capacity to use genetically modified mouse strains and drug interventions has shown the mouse model to be an invaluable research tool defining causal relationships between host immunity and disease and supporting development of new treatments. Used in combination the insights achieved from human and animal experimental infection models provide complementary insights into RV biology and yield novel therapeutic options to reduce the burden of RV-induced disease.

Elucidating the Interaction of CF Airway Epithelial Cells and Rhinovirus: Using the Host-Pathogen Relationship to Identify Future Therapeutic Strategies

Chronic lung disease remains the primary cause of mortality in cystic fibrosis (CF). Growing evidence suggests respiratory viral infections are often more severe in CF compared to healthy peers and contributes to pulmonary exacerbations (PEx) and deterioration of lung function. Rhinovirus is the most prevalent respiratory virus detected, particularly during exacerbations in children with CF <5 years old. However, even though rhinoviral infections are likely to be one of the factors initiating the onset of CF lung disease, there is no effective targeted treatment. A better understanding of the innate immune responses by CF airway epithelial cells, the primary site of infection for viruses, is needed to identify why viral infections are more severe in CF. The aim of this review is to present the clinical impact of virus infection in both young children and adults with CF, focusing on rhinovirus infection. Previous in vitro and in vivo investigations looking at the mechanisms behind virus infection will also be summarized. The review will finish on the potential of transcriptomics to elucidate the host-pathogen responses by CF airway cells to viral infection and identify novel therapeutic targets.

Airway Interleukin-33 and type 2 cytokines in adult patients with acute asthma

BACKGROUND

Several animal studies, and one inoculation study in adult asthmatics have shown that interleukin-33 (IL-33) is a major contributor to type-2 inflammation in acute asthma. However, the link between IL-33 and type-2 inflammation has not been shown in naturally occurring asthma exacerbations.

OBJECTIVES

To determine if airway IL-33 is associated with type-2 inflammation measured by type-2 cytokines, FeNO and sputum eosinophils in patients presenting to the Emergency Department with an asthma exacerbations.

METHODS

Adult patients hospitalized due to acute asthma were enrolled. Upper airways were sampled with nasal swabs and lower airways with induced sputum. Cytokines were measured at protein level using a Luminex® assay and mRNA expression level using droplet-digital-PCR. Airway sampling was repeated four weeks after exacerbation.

RESULTS

At the time of exacerbation, upper airway IL-33 correlated with upper airway IL-5 and IL-13 (R = 0.84, p < 0.01 and R = 0.76, p < 0.01, respectively) and with lower airway IL-13 (R = 0.49, p = 0.03). Similar associations were observed for mRNA expression. Lower airway IL-33 positively correlated with lower airway IL-13 (R = 0.84, p < 0.01). IL-13 and IL-33 were positively correlated with FeNO, and IL-5 with eosinophils. The association between IL-33 and type-2 cytokines were still present four weeks after exacerbation.

CONCLUSION

This is the first study to demonstrate that airway IL-33 is associated with type-2 cytokines in naturally occurring asthma exacerbations in adults, providing in vivo evidence supporting that IL-33 may be driving type-2 inflammation in acute asthma. Thus supporting IL-33 as a potential future drug target due to its role, upstream in the immunological cascade.

Neonatal Immunity, Respiratory Virus Infections, and the Development of Asthma

Infants are exposed to a wide range of potential pathogens in the first months of life. Although maternal antibodies acquired transplacentally protect full-term neonates from many systemic pathogens, infections at mucosal surfaces still occur with great frequency, causing significant morbidity and mortality. At least part of this elevated risk is attributable to the neonatal immune system that tends to favor T regulatory and Th2 type responses when microbes are first encountered. Early-life infection with respiratory viruses is of particular interest because such exposures can disrupt normal lung development and increase the risk of chronic respiratory conditions, such as asthma. The immunologic mechanisms that underlie neonatal host-virus interactions that contribute to the subsequent development of asthma have not yet been fully defined. The goals of this review are (1) to outline the differences between the neonatal and adult immune systems and (2) to present murine and human data that support the hypothesis that early-life interactions between the immune system and respiratory viruses can create a lung environment conducive to the development of asthma.

In Vitro Model of Fully Differentiated Human Nasal Epithelial Cells Infected With Rhinovirus Reveals Epithelium-Initiated Immune Responses

Human rhinoviruses (HRVs) are the commonest cause of the common cold. While HRV is less pathogenic than other respiratory viruses, it is frequently associated with exacerbation of chronic respiratory diseases such as rhinosinusitis and asthma. Nasal epithelial cells are the first sites of viral contact, immune initiation, and airway interconnectivity, but there are limited studies on HRV infection of nasal epithelial cells. Hence, we established a model of HRV infection of in vitro-differentiated human nasal epithelial cells (hNECs) derived from multiple individuals. Through HRV infection of hNECs, we found that HRV mainly targeted ciliated cells and preferentially induced type I and III interferon antiviral pathways. Quantitative polymerase chain reaction analysis of inflammatory genes suggested predominant type 1 immunity signaling and recruitment, with secreted CXCL9, IP-10, CXCL11, and RANTES as likely initiators of airway inflammatory responses. Additionally, we further explored HRV bidirectional release from the hNECs and identified 11 associated genes. Other HRV interactions were also identified through a systematic comparison with influenza A virus infection of hNECs. Overall, this in vitro hNEC HRV infection model provides a platform for repeatable and controlled studies of different individuals, thus providing novel insights into the roles of human nasal epithelium in HRV interaction and immune initiation.

Innate Immune Response to Viral Infections in Primary Bronchial Epithelial Cells is Modified by the Atopic Status of Asthmatic Patients

Purpose

In order to gain an insight into determinants of reported variability in immune responses to respiratory viruses in human bronchial epithelial cells (HBECs) from asthmatics, the responses of HBEC to viral infections were evaluated in HBECs from phenotypically heterogeneous groups of asthmatics and in healthy controls.

Methods

HBECs were obtained during bronchoscopy from 10 patients with asthma (6 atopic and 4 non-atopic) and from healthy controls (n=9) and grown as undifferentiated cultures. HBECs were infected with parainfluenza virus (PIV)-3 (MOI 0.1) and rhinovirus (RV)-1B (MOI 0.1), or treated with medium alone. The cell supernatants were harvested at 8, 24, and 48 hours. IFN-α, CXCL10 (IP-10), and RANTES (CCL5) were analyzed by using Cytometric Bead Array (CBA), and interferon (IFN)-β and IFN-λ1 by ELISA. Gene expression of IFNs, chemokines, and IFN-regulatory factors (IRF-3 and IRF-7) was determined by using quantitative PCR.

Results

PIV3 and RV1B infections increased IFN-λ1 mRNA expression in HBECs from asthmatics and healthy controls to a similar extent, and virus-induced IFN-λ1 expression correlated positively with IRF-7 expression. Following PIV3 infection, IP-10 protein release and mRNA expression were significantly higher in asthmatics compared to healthy controls (median 36.03-fold). No differences in the release or expression of RANTES, IFN-λ1 protein and mRNA, or IFN-α and IFN-β mRNA between asthmatics and healthy controls were observed. However, when asthmatics were divided according to their atopic status, HBECs from atopic asthmatics (n=6) generated significantly more IFN-λ1 protein and demonstrated higher IFN-α, IFN-β, and IRF-7 mRNA expressions in response to PIV3 compared to non-atopic asthmatics (n=4) and healthy controls (n=9). In response to RV1B infection, IFN-β mRNA expression was lower (12.39-fold at 24 hours and 19.37-fold at 48 hours) in non-atopic asthmatics compared to atopic asthmatics.

Conclusions

The immune response of HBECs to virus infections may not be deficient in asthmatics, but seems to be modified by atopic status.

Viral Infections and Associated Factors That Promote Acute Exacerbations of Asthma

Despite asthma being the most common chronic childhood ailment, there is still much to learn about the disease. Early childhood infections with well-known or emerging viruses can lay the pathophysiologic framework for asthma development and exacerbation later in life, which may be due partly to alteration of the airway microbiome. Once asthma is established, acute exacerbations are usually associated with infections with respiratory viruses, such as rhinoviruses (RVs). Once again, there are bidirectional interactions between viruses and airway bacteria that appear to influence the severity of illness and the likelihood of exacerbation. Studies employing recent advances in viral and bacterial identification analytic techniques will clarify these new concepts and may provide the basis for new treatments or prevention or respiratory infection-associated exacerbation. This paper is a review of the associations among respiratory viruses, bacteria, inflammatory mechanisms, and asthma exacerbation.

Rhinovirus induction of fractalkine (CX3CL1) in airway and peripheral blood mononuclear cells in asthma

Rhinovirus infection is associated with the majority of asthma exacerbations. The role of fractalkine in anti-viral (type 1) and pathogenic (type 2) responses to rhinovirus infection in allergic asthma is unknown. To determine whether (1) fractalkine is produced in airway cells and in peripheral blood leucocytes, (2) rhinovirus infection increases production of fractalkine and (3) levels of fractalkine differ in asthmatic compared to non-asthmatic subjects. Fractalkine protein and mRNA levels were measured in bronchoalveolar lavage (BAL) cells and peripheral blood mononuclear cells (PBMCs) from non-asthmatic controls (n = 15) and mild allergic asthmatic (n = 15) subjects. Protein levels of fractalkine were also measured in macrophages polarised ex vivo to give M1 (type 1) and M2 (type 2) macrophages and in BAL fluid obtained from mild (n = 11) and moderate (n = 14) allergic asthmatic and non-asthmatic control (n = 10) subjects pre and post in vivo rhinovirus infection. BAL cells produced significantly greater levels of fractalkine than PBMCs. Rhinovirus infection increased production of fractalkine by BAL cells from non-asthmatic controls (P<0.01) and in M1-polarised macrophages (P<0.05), but not in BAL cells from mild asthmatics or in M2 polarised macrophages. Rhinovirus induced fractalkine in PBMCs from asthmatic (P<0.001) and healthy control subjects (P<0.05). Trends towards induction of fractalkine in moderate asthmatic subjects during in vivo rhinovirus infection failed to reach statistical significance. Fractalkine may be involved in both immunopathological and anti-viral immune responses to rhinovirus infection. Further investigation into how fractalkine is regulated across different cell types and into the effect of stimulation including rhinovirus infection is warranted to better understand the precise role of this unique dual adhesion factor and chemokine in immune cell recruitment.

Immune Responses in Rhinovirus-Induced Asthma Exacerbations

Acute asthma exacerbations are responsible for urgent care visits and hospitalizations; they interfere with school and work productivity, thereby driving much of the morbidity and mortality associated with asthma. Approximately 80 to 85 % of asthma exacerbations in children, adolescents, and less frequently adults are associated with viral upper respiratory tract viral infections, and rhinovirus (RV) accounts for ∼60-70 % of these virus-associated exacerbations. Evidence suggests that it is not the virus itself but the nature of the immune response to RV that drives this untoward response. In particular, evidence supports the concept that RV acts to exacerbate an ongoing allergic inflammatory response to environmental allergens present at the time of the infection. The interaction of the ongoing IgE- and T cell-mediated response to allergen superimposed on the innate and adaptive immune responses to the virus and how this leads to triggering of an asthma exacerbation is discussed.

Host DNA released by NETosis promotes rhinovirus-induced type-2 allergic asthma exacerbation

Respiratory viral infections represent the most common cause of allergic asthma exacerbations. Amplification of the type-2 immune response is strongly implicated in asthma exacerbation, but how virus infection boosts type-2 responses is poorly understood. We report a significant correlation between the release of host double-stranded DNA (dsDNA) following rhinovirus infection and the exacerbation of type-2 allergic inflammation in humans. In a mouse model of allergic airway hypersensitivity, we show that rhinovirus infection triggers dsDNA release associated with the formation of neutrophil extracellular traps (NETs), known as NETosis. We further demonstrate that inhibiting NETosis by blocking neutrophil elastase or by degrading NETs with DNase protects mice from type-2 immunopathology. Furthermore, the injection of mouse genomic DNA alone is sufficient to recapitulate many features of rhinovirus-induced type-2 immune responses and asthma pathology. Thus, NETosis and its associated extracellular dsDNA contribute to the pathogenesis and may represent potential therapeutic targets of rhinovirus-induced asthma exacerbations.

High fractional exhaled nitric oxide and sputum eosinophils are associated with an increased risk of future virus-induced exacerbations: A prospective cohort study

BACKGROUND

The major trigger of asthma exacerbations is infection with a respiratory virus, most commonly rhinovirus. Type 2 inflammation is known to be associated with an increased risk of exacerbations in general. Whether type 2 inflammation at baseline increases the risk of future virus-induced exacerbations is unknown.

OBJECTIVE

To assess whether type 2 inflammation is associated with an increased risk of virus-induced exacerbations of asthma.

METHODS

Stable asthmatics had spirometry, skin prick test, measurement of FeNO and sputum induced for differential cell counts. Patients were followed up for 18 months, during which they were assessed at the research unit when they had symptoms of an exacerbation. Nasal swabs collected at these assessments underwent viral detection by PCR.

RESULTS

A total of 81 asthma patients were recruited, of which 22 (27%) experienced an exacerbation during the follow-up period. Of these, 15 (68%) had a respiratory virus detected at exacerbation. Sputum eosinophils >1% at baseline increased the risk of having a subsequent virus-induced exacerbation (HR 7.6 95% CI: 1.6-35.2, P=.010) as did having FeNO >25 ppb (HR 3.4 95% CI: 1.1-10.4, P=.033).

CONCLUSION AND CLINICAL RELEVANCE

Established type 2 inflammation during stable disease is a risk factor for virus-induced exacerbations in a real-life setting. Measures of type 2 inflammation, such as sputum eosinophils and FeNO, could be included in the risk assessment of patients with asthma in future studies.

Efficacy of novel antibody-based drugs against rhinovirus infection: In vitro and in vivo results

Rhinoviruses (RVs) cause the common cold and are associated with exacerbations of chronic inflammatory respiratory diseases, especially asthma and chronic obstructive pulmonary disease (COPD). We have assessed the antiviral drugs Anaferon for Children (AC) and Ergoferon (containing AC as one of the active pharmaceutical ingredients) in in vitro and in vivo experimental models, in order to evaluate their anti-rhinoviral and immunomodulatory potential. HeLa cells were pretreated with AC, and levels of the interferon-stimulated gene (ISG), 2'-5'-oligoadenylate synthetase 1 (OAS1-A) and viral replication were analyzed. In a mouse model of RV-induced exacerbation of allergic airway inflammation we administered Ergoferon and analyzed its effect on type I (IFN-β), type II (IFN-γ) and type III (IFN-λ) IFNs induction, cell counts in bronchoalveolar lavage (BAL), cytokine (interleukin (IL)-4; IL-6) and chemokine (CXCL10/IP-10; CXCL1/KC) levels. It was shown that AC increased OAS1-А production and significantly decreased viral replication in vitro. Increased IFNs expression together with reduced neutrophils/lymphocytes recruitment and correlated IL-4/IL-6 declination was demonstrated for Ergoferon in vivo. However, there was no effect on examined chemokines. We conclude that AC and Ergoferon possess effects against RV infection and may have potential as novel therapies against RV-induced exacerbations of asthma.

Interactions of Respiratory Viruses and the Nasal Microbiota during the First Year of Life in Healthy Infants

Respiratory viral infections are very frequent in infancy and of importance in acute and chronic disease development. Infections with human rhinovirus (HRV) are, e.g., associated with the later development of asthma. We found that only symptomatic HRV infections were associated with acute changes in the nasal microbiota, mainly characterized by a loss of microbial diversity. Infants with more frequent symptomatic HRV infections had a lower bacterial diversity at the end of the first year of life. Whether the interaction between viruses and the microbiota is one pathway contributing to asthma development will be assessed in the follow-ups of these children. Independent of that, measurements of microbial diversity might represent a potential marker for risk of later lung disease or monitoring of early life interventions.

Traditional culture techniques have shown that increased bacterial colonization is associated with viral colonization; however, the influence of viral colonization on the whole microbiota composition is less clear. We thus aimed to understand the interaction of viral infections and the nasal microbiota in early life to appraise their roles in disease development. Thirty-two healthy, unselected infants were included in this prospective longitudinal cohort study within the first year of life. Biweekly nasal swabs (n = 559) were taken, and the microbiota was analyzed by 16S rRNA pyrosequencing, and 10 different viruses and 2 atypical bacteria were characterized by real-time PCR (combination of seven duplex samples). In contrast to asymptomatic human rhinovirus (HRV) colonization, symptomatic HRV infections were associated with lower alpha diversity (Shannon diversity index [SDI]), higher bacterial density (PCR concentration), and a difference in beta diversities (Jaccard and Bray-Curtis index) of the microbiota. In addition, infants with more frequent HRV infections had a lower SDI at the end of the study period. Overall, changes in the microbiota associated with symptomatic HRV infections were characterized by a loss of microbial diversity. The interaction between HRV infections and the nasal microbiota in early life might be of importance for later disease development and indicate a potential approach for future interventions.

IMPORTANCE Respiratory viral infections are very frequent in infancy and of importance in acute and chronic disease development. Infections with human rhinovirus (HRV) are, e.g., associated with the later development of asthma. We found that only symptomatic HRV infections were associated with acute changes in the nasal microbiota, mainly characterized by a loss of microbial diversity. Infants with more frequent symptomatic HRV infections had a lower bacterial diversity at the end of the first year of life. Whether the interaction between viruses and the microbiota is one pathway contributing to asthma development will be assessed in the follow-ups of these children. Independent of that, measurements of microbial diversity might represent a potential marker for risk of later lung disease or monitoring of early life interventions.

Genetic associations with viral respiratory illnesses and asthma control in children

BACKGROUND

Viral respiratory infections can cause acute wheezing illnesses in children and exacerbations of asthma.

OBJECTIVE

We sought to identify variation in genes with known antiviral and pro-inflammatory functions to identify specific associations with more severe viral respiratory illnesses and the risk of virus-induced exacerbations during the peak fall season.

METHODS

The associations between genetic variation at 326 SNPs in 63 candidate genes and 10 phenotypes related to viral respiratory infection and asthma control were examined in 226 children enrolled in the RhinoGen study. Replication of asthma control phenotypes was performed in 2128 children in the Copenhagen Prospective Study on Asthma in Childhood (COPSAC). Significant associations in RhinoGen were further validated using virus-induced wheezing illness and asthma phenotypes in an independent sample of 122 children enrolled in the Childhood Origins of Asthma (COAST) birth cohort study.

RESULTS

A significant excess of P values smaller than 0.05 was observed in the analysis of the 10 RhinoGen phenotypes. Polymorphisms in 12 genes were significantly associated with variation in the four phenotypes showing a significant enrichment of small P values. Six of those genes (STAT4, JAK2, MX1, VDR, DDX58, and EIF2AK2) also showed significant associations with asthma exacerbations in the COPSAC study or with asthma or virus-induced wheezing phenotypes in the COAST study.

CONCLUSIONS

We identified genetic factors contributing to individual differences in childhood viral respiratory illnesses and virus-induced exacerbations of asthma. Defining mechanisms of these associations may provide insight into the pathogenesis of viral respiratory infections and virus-induced exacerbations of asthma.

MUC18 Regulates Lung Rhinovirus Infection and Inflammation

Background

MUC18 is upregulated in the lungs of asthma and COPD patients. It has been shown to have pro-inflammatory functions in cultured human airway epithelial cells during viral infections and in mice during lung bacterial infections. However, the in vivo role of MUC18 in the context of viral infections remains poorly understood. The goal of this study is to define the in vivo function of MUC18 during respiratory rhinovirus infection.

Methods

Muc18 wild-type (WT) and knockout (KO) mice were infected with human rhinovirus 1B (HRV-1B) and sacrificed after 1 day to determine the inflammatory and antiviral responses. To examine the direct effects of Muc18 on viral infection, tracheal epithelial cells isolated from WT and KO mice were grown under air-liquid interface and infected with HRV-1B. Finally, siRNA mediated knockdown of MUC18 was performed in human airway epithelial cells (AECs) to define the impact of MUC18 on human airway response to HRV-1B.

Results

Both viral load and neutrophilic inflammation were significantly decreased in Muc18 KO mice compared to WT mice. In the in vitro setting, viral load was significantly lower and antiviral gene expression was higher in airway epithelial cells of Muc18 KO mice than the WT mice. Furthermore, in MUC18 knockdown human AECs, viral load was decreased and antiviral gene expression was increased compared to controls.

Conclusions

Our study is the first to demonstrate MUC18’s pro-inflammatory and pro-viral function in an in vivo mouse model of rhinovirus infection.

Update on Human Rhinovirus and Coronavirus Infections

Human rhinovirus (HRV) and coronavirus (HCoV) infections are associated with both upper respiratory tract illness (“the common cold”) and lower respiratory tract illness (pneumonia). New species of HRVs and HCoVs have been diagnosed in the past decade. More sensitive diagnostic tests such as reverse transcription-polymerase chain reaction have expanded our understanding of the role these viruses play in both immunocompetent and immunosuppressed hosts. Recent identification of severe acute respiratory syndrome and Middle East respiratory syndrome viruses causing serious respiratory illnesses has led to renewed efforts for vaccine development. The role these viruses play in patients with chronic lung disease such as asthma makes the search for antiviral agents of increased importance.

Therapeutic implication of genetic variants of IL13 and STAT4 in airway remodelling with bronchial asthma

BACKGROUND

Several gene variants identified in bronchial asthmatic patients are associated with a decrease in pulmonary function. The effects of this intervention on pulmonary function have not been fully researched.

OBJECTIVE

We determined the effects of high-dose inhaled corticosteroids (ICSs) on decreased pulmonary function in asthmatic Japanese patients with variants of IL13 and STAT4 during long-term treatments with low to mild doses of ICS.

METHODS

In this study, 411 patients with bronchial asthma who were receiving ICSs and living in Japan were recruited, were genotyped, and underwent pulmonary function tests and fibreoptic examinations. The effects of 2 years of high-dose ICSs administered to asthmatic patients who were homozygous for IL13 AA of rs20541 or STAT4 TT of rs925847 and who progressed to airway remodelling were investigated.

RESULTS

High-dose ICS treatment increased the pulmonary function of patients homozygous for IL13 AA of rs20541 but not of patients homozygous for STAT4 TT of rs925847. The increased concentrations of the mediators IL23, IL11, GMCSF, hyaluronic acid, IL24, and CCL8 in bronchial lavage fluid (BLF) were diminished after high-dose ICS treatment in patients homozygous for IL13 AA of rs20541.

CONCLUSION AND CLINICAL RELEVANCE

IL13 AA of rs20541 and STAT4 TT of rs925847 are potential genomic biomarkers for predicting lower pulmonary function. The administration of high-dose ICSs to asthmatic patients with genetic variants of IL13 AA may inhibit the advancement of airway remodelling. The genetic variants of STAT4 TT did not respond to high-dose ICSs. Therefore, using medications other than ICSs must be considered even during the initial treatment of bronchial asthma. These genetic variants may aid in the realization of personalized and phenotype-specific therapies for bronchial asthma.

The healthy workplace project: Reduced viral exposure in an office setting

Viral illnesses such as gastroenteritis and the common cold create a substantial burden in the workplace due to reduced productivity, increased absenteeism, and increased health care costs. Behaviors in the workplace contribute to the spread of human viruses via direct contact between hands, contaminated surfaces, and the mouth, eyes, and/or nose. This study assessed whether implementation of the Healthy Workplace Project (HWP) (providing hand sanitizers, disinfecting wipes, facial tissues, and use instructions) would reduce viral loads in an office setting of approximately 80 employees after seeding fomites and the hands of volunteer participants with an MS-2 phage tracer. The HWP significantly reduced viable phage detected on participants' hands, communal fomites, and personal fomites (p ≤ .010) in office environments and presents a cost-effective method for reducing the health and economic burden associated with viral illnesses in the workplace.

Rhinovirus in the Pathogenesis and Clinical Course of Asthma

In healthy individuals, human rhinovirus (HRV) infections are the major cause of the common cold. These are generally uncomplicated infections except for occasional cases of otitis media or sinusitis. In individuals with asthma, however, HRV infections can have a major impact on disease development and progression. HRV-induced wheezing illnesses in early life are a significant risk factor for subsequent development of asthma, and growing evidence supports a role of recurrent HRV infections in the development and progression of several aspects of airway remodeling in asthma. In addition, HRV infections are one of the most common triggers for acute exacerbations of asthma, which represent a major burden to health-care systems around the world. None of the currently prescribed medications for asthma are effective in preventing or reversing asthma development and airway remodeling or are ideal for treating HRV-induced exacerbations of asthma. Thus, a better understanding of the role of HRV in asthma is important if we are to develop more effective therapies. In the past decade, we have gained new insights into the role of HRV infections in the development and progression of airway remodeling as well as a new appreciation for the proinflammatory and host defense responses to HRV infections that may help to regulate susceptibility to asthma exacerbations. This article reviews the current understanding of the role HRV infections play in the pathogenesis of asthma and identifies possible avenues to new therapeutic strategies for limiting the effects of HRV infections in asthma.

Basal salivary cortisol secretion and susceptibility to upper respiratory infection

The immunosuppressive effects of glucocorticoids (GCs) are well-established. However, whether the net effect of GC-elicited alterations in immune function is sufficient to influence a clinically relevant outcome in healthy adults has yet to be shown. The aim of the present study was to investigate whether inter-individual differences in basal salivary cortisol production are associated with increased risk and severity of infection and subsequent illness following experimental exposure to a virus that causes the common cold. The present analyses combine archival data from three viral-challenge studies. Participants were 608 healthy adults, aged 18 to 55 years (49.2% female; 65.8% white), who each completed a three-day saliva collection protocol; was subsequently exposed to a virus that causes the common cold; and monitored for 5 days for objective signs of infection (presence of challenge virus in nasal secretions) and clinical illness (mucus weight, mucociliary clearance time). Basal cortisol production (operationalized as the calculated area-under-the-curve averaged across the 3 days) showed a graded association with infection risk, with those producing higher levels of cortisol being at greater risk. Cortisol also showed a continuous association with duration of viral shedding, an indicator of viral replication and continuing infection, such that higher cortisol concentrations predicted more days of shedding. Cortisol was not, however, related to severity of objective illness. These findings are the first to demonstrate in healthy adults an association between basal cortisol production and an objectively measured and clinically relevant infectious disease outcome.

Altered Innate Immune Responses in Neutrophils from Patients with Well- and Suboptimally Controlled Asthma

BACKGROUND

Respiratory infections are a major cause of asthma exacerbations where neutrophilic inflammation dominates and is associated with steroid refractory asthma. Structural airway cells in asthma differ from nonasthmatics; however it is unknown if neutrophils differ. We investigated neutrophil immune responses in patients who have good (AGood) and suboptimal (ASubopt) asthma symptom control.

METHODS

Peripheral blood neutrophils from AGood (ACQ < 0.75, n = 11), ASubopt (ACQ > 0.75, n = 7), and healthy controls (HC) (n = 9) were stimulated with bacterial (LPS (1 μg/mL), fMLF (100 nM)), and viral (imiquimod (3 μg/mL), R848 (1.5 μg/mL), and poly I:C (10 μg/mL)) surrogates or live rhinovirus (RV) 16 (MOI1). Cell-free supernatant was collected after 1 h for neutrophil elastase (NE) and matrix metalloproteinase- (MMP-) 9 measurements or after 24 h for CXCL8 release. Results. Constitutive NE was enhanced in AGood neutrophils compared to HC. fMLF stimulated neutrophils from ASubopt but not AGood produced 50% of HC levels. fMLF induced MMP-9 was impaired in ASubopt and AGood compared to HC. fMLF stimulated CXCL8 but not MMP-9 was positively correlated with FEV1 and FEV1/FVC. ASubopt and AGood responded similarly to other stimuli.

CONCLUSIONS

Circulating neutrophils are different in asthma; however, this is likely to be related to airflow limitation rather than asthma control.

Airway factor XIII associates with type 2 inflammation and airway obstruction in asthmatic patients

BACKGROUND

Coagulation Factor XIII (FXIII) plays an important role in wound healing by stabilizing fibrin clots and cross-linking extracellular matrix proteins. FXIII is expressed in cells of the monocyte/macrophage and dendritic cell lineages in response to type 2 cytokines.

OBJECTIVE

We sought to determine the association between FXIII and asthma pathobiology.

METHODS

We analyzed the expression of FXIII mRNA and protein levels in bronchoalveolar lavage samples obtained before and after segmental allergen challenge from patients with mild asthma and in induced sputum samples collected from patients with mild-to-moderate and severe asthma.

RESULTS

FXIII mRNA and protein levels were highly upregulated in bronchoalveolar cells and fluid after allergen challenge and mRNA levels correlated with protein levels. In sputum of asthmatic patients, FXIII expression was positively correlated with type 2 immune response and dendritic cell markers (CD209 and CD207). FXIII expression was also associated with increased airflow limitation (FEV1/forced vital capacity and residual volume/total lung capacity ratios) and greater reversibility to β-agonists.

CONCLUSIONS

FXIII expression was upregulated in the airways of asthmatic patients after allergen exposure. Expression in the sputum of asthmatic patients correlated with the type 2 immune response and airflow limitation. Excessive activity of FXIII could contribute to the pathophysiology of airway obstruction in asthmatic patients.

Does moderate intensity exercise attenuate the postprandial lipemic and airway inflammatory response to a high-fat meal?

We investigated whether an acute bout of moderate intensity exercise in the postprandial period attenuates the triglyceride and airway inflammatory response to a high-fat meal (HFM) compared to remaining inactive in the postprandial period. Seventeen (11 M/6 F) physically active (≥ 150 min/week of moderate-vigorous physical activity (MVPA)) subjects were randomly assigned to an exercise (EX; 60% VO 2peak) or sedentary (CON) condition after a HFM (10 kcal/kg, 63% fat). Blood analytes and airway inflammation via exhaled nitric oxide (eNO) were measured at baseline, and 2 and 4 hours after HFM. Airway inflammation was assessed with induced sputum and cell differentials at baseline and 4 hours after HFM. Triglycerides doubled in the postprandial period (~113 ± 18%, P < 0.05), but the increase did not differ between EX and CON. Percentage of neutrophils was increased 4 hours after HFM (~17%), but the increase did not differ between EX and CON. Exhaled nitric oxide changed nonlinearly from baseline to 2 and 4 hours after HFM (P < 0.05, η (2) = 0.36). Our findings suggest that, in active individuals, an acute bout of moderate intensity exercise does not attenuate the triglyceride or airway inflammatory response to a high-fat meal.

IL-33-dependent type 2 inflammation during rhinovirus-induced asthma exacerbations in vivo

RATIONALE

Rhinoviruses are the major cause of asthma exacerbations; however, its underlying mechanisms are poorly understood. We hypothesized that the epithelial cell-derived cytokine IL-33 plays a central role in exacerbation pathogenesis through augmentation of type 2 inflammation.

OBJECTIVES

To assess whether rhinovirus induces a type 2 inflammatory response in asthma in vivo and to define a role for IL-33 in this pathway.

METHODS

We used a human experimental model of rhinovirus infection and novel airway sampling techniques to measure IL-4, IL-5, IL-13, and IL-33 levels in the asthmatic and healthy airways during a rhinovirus infection. Additionally, we cultured human T cells and type 2 innate lymphoid cells (ILC2s) with the supernatants of rhinovirus-infected bronchial epithelial cells (BECs) to assess type 2 cytokine production in the presence or absence of IL-33 receptor blockade.

MEASUREMENTS AND MAIN RESULTS

IL-4, IL-5, IL-13, and IL-33 are all induced by rhinovirus in the asthmatic airway in vivo and relate to exacerbation severity. Further, induction of IL-33 correlates with viral load and IL-5 and IL-13 levels. Rhinovirus infection of human primary BECs induced IL-33, and culture of human T cells and ILC2s with supernatants of rhinovirus-infected BECs strongly induced type 2 cytokines. This induction was entirely dependent on IL-33.

CONCLUSIONS

IL-33 and type 2 cytokines are induced during a rhinovirus-induced asthma exacerbation in vivo. Virus-induced IL-33 and IL-33-responsive T cells and ILC2s are key mechanistic links between viral infection and exacerbation of asthma. IL-33 inhibition is a novel therapeutic approach for asthma exacerbations.

Roflumilast improves corticosteroid resistance COPD bronchial epithelial cells stimulated with toll like receptor 3 agonist

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterised by chronic pulmonary inflammation punctuated by periods of viral exacerbations. Recent evidence suggests that the combination of roflumilast with corticosteroids may improve the compromised anti-inflammatory properties of corticosteroids in COPD. We analyzed differential and combination anti-inflammatory effects of dexamethasone and roflumilast N-oxide in human bronchial epithelial cells (HBECs) stimulated with viral toll like receptor (TLR) agonists.

METHODS

Lung tissue and HBECs were isolated from healthy (n = 15), smokers (n = 12) and smokers with COPD (15). TLR3 expression was measured in lung tissue and in HBECs. IL-8 secretion was measured in cell cultures after TLR3 stimulation with poly I:C 10 μg/mL.

RESULTS

We found that TLR3 expression was increased by 1.95 fold (protein) and 2.5 fold (mRNA) in lung tissues from smokers with COPD and inversely correlated with lung function. The TLR3 agonist poly I:C 10 μg/mL increased the IL-8 release in HBECs that was poorly inhibited by dexamethasone in smokers (24.5%) and smokers with COPD (21.6%). In contrast, roflumilast showed similar inhibitory effects on IL-8 release in healthy (58.8%), smokers (56.6%) and smokers with COPD (50.5%). The combination of roflumilast N-oxide and dexamethasone showed additive inhibitory effects. Mechanistically, roflumilast N-oxide when combined with dexamethasone increased the expression of MKP1, and enhanced the inhibitory effects on phospho-p38, AP1 and NFκB activities which may explain the additive anti-inflammatory effects.

CONCLUSIONS

Altogether, our data provide in vitro evidence for a possible clinical utility to add roflumilast on top of inhaled corticosteroid in COPD.

Utility of animal and in vivo experimental infection of humans with rhinoviruses in the development of therapeutic agents for viral exacerbations of asthma and chronic obstructive pulmonary disease

There is an association with acute viral infection of the respiratory tract and exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Although these exacerbations are associated with several types of viruses, human rhinoviruses (HRVs) are associated with the vast majority of disease exacerbations. Due to the lack of an animal species that is naturally permissive for HRVs to use as a facile model system, and the limitations associated with animal models of asthma and COPD, studies of controlled experimental infection of humans with HRVs have been used and conducted safely for decades. This review discusses how these experimental infection studies with HRVs have provided a means of understanding the pathophysiology underlying virus-induced exacerbations of asthma and COPD with the goal of developing agents for their prevention and treatment.

Interferon gene expression in sputum cells correlates with the Asthma Index Score during virus-induced exacerbations

Background

The majority of asthma exacerbations are related to viral respiratory infections. Some, but not all, previous studies have reported that low interferon responses in patients with asthma increase the risk for virus‐induced exacerbations.

Objective

We sought to determine the relationship between lower airway inflammatory biomarkers, specifically interferon gene expression, and the severity or presence of an exacerbation in asthmatics experiencing a naturally occurring viral infection.

Methods

Sputum samples were analysed from subjects in an asthma exacerbation study who experienced a confirmed viral infection. Subjects were monitored for daily symptoms, medication use and peak expiratory flow rate until baseline. Sputum samples were assessed for cell counts and gene expression.

Results

Interferon gamma expression was significantly greater in patients with asthma exacerbations compared to non‐exacerbating patients (P = 0.002). IFN‐α1, IFN‐β1 and IFN‐γ mRNA levels correlated with the peak Asthma Index (r = 0.58, P < 0.001; r = 0.57, P = 0.001; and r = 0.51, P = 0.004, respectively). Additionally, IL‐13, IL‐10 and eosinophil major basic protein mRNA levels were greater in patients with asthma exacerbations compared to non‐exacerbating patients (P = 0.03, P = 0.06 and P = 0.02, respectively), and IL‐13 mRNA correlated with the peak Asthma Index (P = 0.006).

Conclusions

Our findings indicate that asthma exacerbations are associated with increased rather than decreased expression of interferons early in the course of infection. These findings raise the possibility that excessive virus‐induced interferon production during acute infections can contribute to airway inflammation and exacerbations of asthma.

Human rhinovirus induced cytokine/chemokine responses in human airway epithelial and immune cells

Infections with human rhinovirus (HRV) are commonly associated with acute upper and lower respiratory tract disease and asthma exacerbations. The role that HRVs play in these diseases suggests it is important to understand host-specific or virus-specific factors that contribute to pathogenesis. Since species A HRVs are often associated with more serious HRV disease than species B HRVs, differences in immune responses they induce should inform disease pathogenesis. To identify species differences in induced responses, we evaluated 3 species A viruses, HRV 25, 31 and 36 and 3 species B viruses, HRV 4, 35 and 48 by exposing human PBMCs to HRV infected Calu-3 cells. To evaluate the potential effect of memory induced by previous HRV infection on study responses, we tested cord blood mononuclear cells that should be HRV naïve. There were HRV-associated increases (significant increase compared to mock-infected cells) for one or more HRVs for IP-10 and IL-15 that was unaffected by addition of PBMCs, for MIP-1α, MIP-1β, IFN-α, and HGF only with addition of PBMCs, and for ENA-78 only without addition of PBMCs. All three species B HRVs induced higher levels, compared to A HRVs, of MIP-1α and MIP-1β with PBMCs and ENA-78 without PBMCs. In contrast, addition of CBMCs had less effect and did not induce MIP-1α, MIP-1β, or IFN-α nor block ENA-78 production. Addition of CBMCs did, however, increase IP-10 levels for HRV 35 and HRV 36 infection. The presence of an effect with PBMCs and no effect with CBMCs for some responses suggest differences between the two types of cells possibly because of the presence of HRV memory responses in PBMCs and not CBMCs or limited response capacity for the immature CBMCs relative to PBMCs. Thus, our results indicate that different HRV strains can induce different patterns of cytokines and chemokines; some of these differences may be due to differences in memory responses induced by past HRV infections, and other differences related to virus factors that can inform disease pathogenesis.

Nasal lavage VEGF and TNF-α levels during a natural cold predict asthma exacerbations

BACKGROUND

Asthma exacerbations contribute to significant morbidity, mortality and healthcare utilization. Furthermore, viral infections are associated with asthma exacerbations by mechanisms that are not fully understood.

OBJECTIVE

The aim of this analysis was to determine whether cytokine patterns in patients with colds could identify risks for subsequent asthma exacerbations.

METHODS

We analysed cytokine levels in nasal lavage fluid (NLF) in 59 subjects (46 with asthma) with acute upper respiratory symptoms and after symptomatic resolution. Analyte choice was based on potential relevance to asthma exacerbations: antiviral (IFN-α, IFN-β, IFN-γ, IFN-λ1, IP-10, TRAIL), cell recruiting (G-CSF, IL-1β, IL-8, MCP-1, MCP-3, TNF-α), polarizing (CXCL13, IL-10, IL-13, IL-17, TSLP), and injury remodelling (fibronectin, IL-33, MMP-9, VEGF).

RESULTS

The overall cytokine response induced during viral infections was not different between asthmatic and non-asthmatic individuals for a wide array of cytokines. However, mean levels of VEGF, TNF-α and IL-1β were 1.7-, 5.1- and 4.7-fold higher in samples from asthma subjects who exacerbated in the first 3 weeks of the cold compared with those who did not exacerbate (P = 0.006, 0.01, 0.048, respectively). Using receiver operating characteristic curve-defined thresholds, high VEGF and TNF-α levels predicted a shorter time-to-exacerbation after NLF sampling (25% exacerbation rate: 3 vs. 45 days, and 3 vs. 26 days; P = 0.03, 0.04, respectively).

CONCLUSION AND CLINICAL RELEVANCE

Although they produce similar cytokine responses to viral infection as non-asthmatics, asthmatics with higher levels of VEGF and TNF-α in NLF obtained during acute cold phases predicted subsequent asthma exacerbations in this cohort of patients with mild-to-moderate disease. In the future, stratifying the risk of an asthma exacerbation by cytokine profile may aid the targeting of personalized treatment and intervention strategies.