Interleukin-10 gene expression in acute virus-induced asthma

Herpes zoster burden in patients with asthma: real-world incidence, healthcare resource utilisation and cost

BACKGROUND

Herpes zoster (HZ) is a painful condition caused by reactivation of the varicella-zoster virus. The objectives of this study were to compare HZ incidence in adults with asthma versus adults without asthma and to compare healthcare resource use as well as direct costs in adults with HZ and asthma versus adults with asthma alone in the USA.

METHODS

This retrospective longitudinal cohort study included adults aged ≥18 years across the USA. Patients were identified from Optum's deidentified Clinformatics Data Mart Database, an administrative claims database, between 1 October 2015 and 28 February 2020, including commercially insured and Medicare Advantage with part D beneficiaries. Cohorts of patients with and without asthma, and separate cohorts of patients with asthma and HZ and with asthma but not HZ, were identified using International Classification of Diseases 10th Revision, Clinical Modification codes. HZ incidence, healthcare resource use and costs were compared, adjusting for baseline characteristics, between the relevant cohorts using generalised linear models.

RESULTS

HZ incidence was higher in patients with asthma (11.59 per 1000 person-years) than patients without asthma (7.16 per 1000 person-years). The adjusted incidence rate ratio (aIRR) for HZ in patients with asthma, compared with patients without asthma, was 1.34 (95% CI 1.32 to 1.37). Over 12 months of follow-up, patients with asthma and HZ had more inpatient stays (aIRR 1.11; 95% CI 1.02 to 1.21), emergency department visits (aIRR 1.26; 95% CI 1.18 to 1.34) and outpatient visits (aIRR 1.19; 95% CI 1.16 to 1.22), and direct healthcare costs that were US dollars ($) 3058 (95% CI $1671 to $4492) higher than patients with asthma without HZ.

CONCLUSION

Patients with asthma had a higher incidence of HZ than those without asthma, and among patients with asthma HZ added to their healthcare resource use and costs.

Prevalence of acute infection in adults with asthma exacerbation: A systematic review and meta-analysis

BACKGROUND

Acute respiratory infections are a major trigger of asthma exacerbations. This study sought to estimate the overall proportion of viruses, atypical pathogens, and bacteria detected in adults with asthma exacerbations.

METHODS

PubMed, EMBASE, and Cochrane Library databases and all related studies from the reviews and references were searched from inception to February 13, 2020. Two authors independently performed study selection, data extraction, as well as quality evaluation. Subsequently, meta-analysis, between-study heterogeneity, and publication bias assessment were conducted on RStudio.

RESULTS

Forty-three eligible studies comprising 3511 adults were included, of which 21 publications mentioned multiple infections during acute asthma attacks. Meta-analysis showed an acute infection prevalence of 40.19% (95% confidence interval [CI] 34.53%-45.99%). Viruses, atypical pathogens, and bacteria were detected in 38.76% (95% CI 32.02%-45.71%), 8.29% (95% CI 2.64%-16.27%), and 7.05% (95% CI 3.34%-11.81%) of asthmatics during exacerbations, respectively. Rhinovirus infections are always the dominant trigger for exacerbations with a proportion of 20.02% (95% CI 14.84%-25.73%). Substantial heterogeneity across studies (Cochran Q test: 479.43, P < 0.0001, I2 = 91.2%) was explained by subgroup analysis, indicating that year, region, population, respiratory secretion, detection method, pathogen, and study quality were all influencing factors.

CONCLUSION

This meta-analysis provided the first quantitative epidemiological data for adults, and in the future, more research and health-care supports are necessary in this area.

Efficacy and safety of intravenous leukotriene receptor antagonists in acute asthma

The incidence of bronchial asthma has increased substantially since recent decades in both children and adults. Moreover, the number of patients presenting with asthma exacerbation to the emergency department has also increased in several countries. Leukotrienes are inflammatory mediators that play an important role in bronchial asthma exacerbation. Leukotriene receptor antagonists reduce asthma exacerbation in chronic asthma; moreover, the current guidelines for asthma management recommend the use of oral leukotriene receptor antagonists for asthma control and reduce further exacerbation. However, data on the use of intravenous leukotriene receptor antagonists during acute asthma exacerbation are scarce. Nevertheless, currently available data revealed a trend of significant improvement of acute asthma and rapid reversal of airflow obstruction when administered during an acute asthma attack. This review aims to summarize currently available data on the use of intravenous leukotriene receptor antagonists in adult patients with acute asthma exacerbation.

The need for vaccination in adults with chronic (noncommunicable) diseases in India - lessons from around the world

Worldwide, chronic diseases (noncommunicable diseases [NCDs]) cause 41 million (71%) deaths annually. They are the leading cause of mortality in India, contributing to 60% of total deaths each year. Individuals with these diseases are more susceptible to vaccine-preventable diseases (VPDs) and have an increased risk of associated disease severity and complications. This poses a substantial burden on healthcare systems and economies, exemplified by the COVID-19 pandemic. Vaccines are an effective strategy to combat these challenges; however, utilization rates are inadequate. With India running one of the world’s largest COVID-19 vaccination programs, this presents an opportunity to improve vaccination coverage for all VPDs. Here we discuss the burden of VPDs in those with NCDs, the benefit of vaccinations, current challenges and possible strategies that may facilitate implementation and accessibility of vaccination programs. Effective vaccination will have a significant impact on the disease burden of both VPDs and NCDs and beyond.

What is already known on this topic?

Annually, chronic or noncommunicable diseases (NCDs) cause >40 million deaths worldwide and 60% of all deaths in India

Adults with these diseases are more susceptible to vaccine-preventable diseases (VPDs); however, vaccine utilization is inadequate in this population

What is added by this report?

We highlight the benefits of vaccination in adults with NCDs that extend beyond disease prevention

We discuss key challenges in implementing adult vaccination programs and provide practical solutions

What are the implications for public health practice?

Raising awareness about the benefits of vaccinations, particularly for those with NCDs, and providing national guidelines with recommendations from medical societies, will increase vaccine acceptance

Adequate vaccine acceptance will reduce the VPD burden in this vulnerable population

IL-33 Induces an Antiviral Signature in Mast Cells but Enhances Their Permissiveness for Human Rhinovirus Infection

Mast cells (MCs) are classically associated with allergic asthma but their role in antiviral immunity is unclear. Human rhinoviruses (HRVs) are a major cause of asthma exacerbations and can infect and replicate within MCs. The primary site of HRV infection is the airway epithelium and MCs localise to this site with increasing asthma severity. The asthma susceptibility gene, IL-33, encodes an epithelial-derived cytokine released following HRV infection but its impact on MC antiviral responses has yet to be determined. In this study we investigated the global response of LAD2 MCs to IL-33 stimulation using RNA sequencing and identified genes involved in antiviral immunity. In spite of this, IL-33 treatment increased permissiveness of MCs to HRV16 infection which, from the RNA-Seq data, we attributed to upregulation of ICAM1. Flow cytometric analysis confirmed an IL-33-dependent increase in ICAM1 surface expression as well as LDLR, the receptors used by major and minor group HRVs for cellular entry. Neutralisation of ICAM1 reduced the IL-33-dependent enhancement in HRV16 replication and release in both LAD2 MCs and cord blood derived MCs. These findings demonstrate that although IL-33 induces an antiviral signature in MCs, it also upregulates the receptors for HRV entry to enhance infection. This highlights the potential for a gene-environment interaction involving IL33 and HRV in MCs to contribute to virus-induced asthma exacerbations.

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.

Viral Infection and Airway Epithelial Immunity in Asthma

Viral respiratory tract infections are associated with asthma development and exacerbation in children and adults. In the course of immune responses to viruses, airway epithelial cells are the initial platform of innate immunity against viral invasion. Patients with severe asthma are more vulnerable than those with mild to moderate asthma to viral infections. Furthermore, in most cases, asthmatic patients tend to produce lower levels of antiviral cytokines than healthy subjects, such as interferons produced from immune effector cells and airway epithelial cells. The epithelial inflammasome appears to contribute to asthma exacerbation through overactivation, leading to self-damage, despite its naturally protective role against infectious pathogens. Given the mixed and complex immune responses in viral-infection-induced asthma exacerbation, this review examines the diverse roles of airway epithelial immunity and related potential therapeutic targets and discusses the mechanisms underlying the heterogeneous manifestations of asthma exacerbations.

Mechanism of Rhinovirus Immunity and Asthma

The majority of asthma exacerbations in children are caused by Rhinovirus (RV), a positive sense single stranded RNA virus of the Picornavirus family. The host has developed virus defense mechanisms that are mediated by the upregulation of interferon-activated signaling. However, the virus evades the immune system by inducing immunosuppressive cytokines and surface molecules like programmed cell death protein 1 (PD-1) and its ligand (PD-L1) on immunocompetent cells. Initially, RV infects epithelial cells, which constitute a physiologic mucosal barrier. Upon virus entrance, the host cell immediately recognizes viral components like dsRNA, ssRNA, viral glycoproteins or CpG-DNA by host pattern recognition receptors (PRRs). Activation of toll like receptors (TLR) 3, 7 and 8 within the endosome and through MDA-5 and RIG-I in the cytosol leads to the production of interferon (IFN) type I and other antiviral agents. Every cell type expresses IFNAR1/IFNAR2 receptors thus allowing a generalized antiviral activity of IFN type I resulting in the inhibition of viral replication in infected cells and preventing viral spread to non-infected cells. Among immune evasion mechanisms of the virus, there is downregulation of IFN type I and its receptor as well as induction of the immunosuppressive cytokine TGF-β. TGF-β promotes viral replication and is associated with induction of the immunosuppression signature markers LAP3, IDO and PD-L1. This article reviews the recent advances on the regulation of interferon type I expression in association with RV infection in asthmatics and the immunosuppression induced by the virus.

Induction of IL-25 Expression in Human Nasal Polyp Epithelium by Influenza Virus Infection is Abated by Interferon-Alpha Pretreatment

Background

Epithelial cytokines including IL-25, IL-33 and thymic stromal lymphopoietin (TLSP) are recently established as drivers of type 2 chronic inflammatory diseases such as chronic rhinosinusitis with nasal polyps (CRSwNP). Here, we further confirmed the increased expression of IL-25 in CRSwNP and investigated potential contributors of IL-25 in CRSwNP epithelium.

Methods

Sixty CRSwNP, 25 CRSsNP and 15 healthy control tissues were examined for IL-25 expression and for the accompanying type 2 inflammatory cytokines. We then tested different respiratory virus infections on human nasal epithelial cells (hNECs) for their ability to trigger IL-25 expression. In addition, we subjected hNECs generated from CRSwNP tissues to pretreatment with recombinant interferon-alpha (IFN-α) prior to viral infection to evaluate IFN effects on IL-25 induction.

Results

We confirmed that significantly enhanced levels of IL-25 were observed in CRSwNP tissues, and that IL-25 expression correlated with type 2 inflammatory cytokine expression. In vitro, we observed significantly elevated IL-25 in hNECs infected with influenza A virus as early as 24 hours post-infection (hpi), regardless of tissue origin, and IL-25 correlated positively with viral load. While other respiratory viruses exhibited increasing trends of IL-25, these were not significant at the time-points tested. IFN-α treatment of CRSwNP epithelium was found to exert bimodal effects, ie IFN-α treatment alone induced moderate IL-25 expression, whereas IFN-α pretreatment of hNECs before influenza infection significantly diminished IL-25 induction by active influenza virus infection.

Conclusion

We have authenticated the observation of elevated IL-25 in CRSwNP, which is correlated with type 2 inflammatory cytokines. Notably, we identified influenza virus infection as a potential contributor of IL-25 in both control and CRSwNP epithelium during active infection. This IL-25 induction can be abated by IFN-α pretreatment which ameliorated active influenza infection.

Trial Registration

Chictr.org.cn ChiCTR-BON-16010179, Registered 18 December 2016, http://www.chictr.org.cn/showproj.aspx?proj=17331. The authors agree on the sharing of deidentified participant data where it pertains to request directly related to the data in this article when contacted (Haiyu Hong; honghy@mail.sysu.edu.cn).

Infection-Associated Mechanisms of Neuro-Inflammation and Neuro-Immune Crosstalk in Chronic Respiratory Diseases

Chronic obstructive airway diseases are characterized by airflow obstruction and airflow limitation as well as chronic airway inflammation. Especially bronchial asthma and chronic obstructive pulmonary disease (COPD) cause considerable morbidity and mortality worldwide, can be difficult to treat, and ultimately lack cures. While there are substantial knowledge gaps with respect to disease pathophysiology, our awareness of the role of neurological and neuro-immunological processes in the development of symptoms, the progression, and the outcome of these chronic obstructive respiratory diseases, is growing. Likewise, the role of pathogenic and colonizing microorganisms of the respiratory tract in the development and manifestation of asthma and COPD is increasingly appreciated. However, their role remains poorly understood with respect to the underlying mechanisms. Common bacteria and viruses causing respiratory infections and exacerbations of chronic obstructive respiratory diseases have also been implicated to affect the local neuro-immune crosstalk. In this review, we provide an overview of previously described neuro-immune interactions in asthma, COPD, and respiratory infections that support the hypothesis of a neuro-immunological component in the interplay between chronic obstructive respiratory diseases, respiratory infections, and respiratory microbial colonization.

Assessment of the Association of COPD and Asthma with In-Hospital Mortality in Patients with COVID-19. A Systematic Review, Meta-Analysis, and Meta-Regression Analysis

Together, chronic obstructive pulmonary disease (COPD) and asthma account for the most common non-infectious respiratory pathologies. Conflicting preliminary studies have shown varied effect for COPD and asthma as prognostic factors for mortality in coronavirus disease 2019 (COVID-19). The aim of this study was to explore the association of COPD and asthma with in-hospital mortality in patients with COVID-19 by systematically reviewing and synthesizing with a meta-analysis the available observational studies. MEDLINE, Scopus, and medRxiv databases were reviewed. A random-effects model meta-analysis was used, and I-square was utilized to assess for heterogeneity. In-hospital mortality was defined as the primary endpoint. Sensitivity and meta-regression analyses were performed. Thirty studies with 21,309 patients were included in this meta-analysis (1465 with COPD and 633 with asthma). Hospitalized COVID-19 patients with COPD had higher risk of death compared to those without COPD (OR: 2.29; 95% CI: 1.79–2.93; I² 59.6%). No significant difference in in-hospital mortality was seen in patients with and without asthma (OR: 0.87; 95% CI: 0.68–1.10; I² 0.0%). The likelihood of death was significantly higher in patients with COPD that were hospitalized with COVID-19 compared to patients without COPD. Further studies are needed to assess whether this association is independent or not. No significant difference was demonstrated in COVID-19-related mortality between patients with and without asthma.

IL-35 and IL-37 are negatively correlated with high IgE production among children with asthma in Saudi Arabia

BACKGROUND

Asthma is one of the most prevalent inflammatory disorders among children in Saudi Arabia.

OBJECTIVE

This study aimed to determine the correlation between the serum levels of vitamin D, immunoglobulin E (IgE), and cytokine (interferon-gamma (IFN-γ), interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-13, IL-35, and IL-37) in relation to the severity of disease in patients with asthma.

METHODS

This case-control study was carried out at King Abdullah Specialist Children's Hospital, Saudi Arabia, and included 48 patients with asthma and 47 matched controls, aged 6-14 years. A validated questionnaire was administered to the participants, after which each patient with asthma underwent pulmonary function tests. The serum levels of vitamin D, IgE, IFN-γ, IL-1β, IL-4, IL-6, IL-10, IL-13, IL-35, and IL-37 of each participant were also measured.

RESULTS

Patients with asthma demonstrated significantly higher IgE and cytokine (IL-1β, IL-4, IL-6, IL-10, IL-13, IL-35, and IL-37) levels compared to the control group (p value < .001). The levels of IL-1β, IL-4, IL-10, and IL-13 were consistently positively correlated with the serum levels of IgE among patients with asthma. However, the IgE levels in patients with asthma were consistently negatively correlated with IL-35 and IL-37.

CONCLUSIONS

We found significantly higher levels of eosinophils, IgE, IL-1β, IL-4, IL-6, IL-10, IL-13, IL-35, and IL-37 in patients with asthma compared to the controls, but no relationship between vitamin D and asthma.

Changes in the Th9 cell population and related cytokines in the peripheral blood of infants with recurrent wheezing

Introduction

T helper type 9 (Th9) cells have been shown to play a key role in initiating allergic reactions and promoting airway inflammation. However, to the best of our knowledge, their role has not been analyzed in infants with recurrent wheezing.

Material and methods

We performed a case-control study including 34 infants with recurrent wheezing and the same number of healthy infants as controls; all subjects were aged 1- to 3-years-old. The Th9 cell populations in the peripheral blood of these subjects were analyzed using flow cytometry, along with the assessment of Th9- and Th2-related plasma cytokine levels, including interleukin (IL)-1β, IL-4, IL-5, IL-9, IL-10, IL-13, IL-17A, and IL-33, and transforming growth factor β1 (TGF-β1) using a Luminex 200 immunoassay.

Results

Our results indicatedthat infants with recurrent wheezing had higher percentages of Th9 cells (median, 0.69%; range, 0.46-1.08%) as compared to healthy infants (median, 0.25%, range, 0.13-0.36%; p < 0.05). In addition, infants with recurrent wheezing also exhibited higher plasma levels of cytokines IL-4, IL-9, IL-10, IL-33, and TGF-β1. Furthermore, the percentage of Th9 cells was positively correlated with the levels of IL-4 (r = 0.408, p < 0.05) and IL-9 (r = 0.644, p < 0.05) in the peripheral blood of wheezing infants.

Conclusions

Our findings suggest that the percentage of Th9 cells is increased in infants with recurrent wheezing; thus, Th9 cells may play an important role in the pathogenesis of recurrent wheezing.

Respiratory Viral Infections in Exacerbation of Chronic Airway Inflammatory Diseases: Novel Mechanisms and Insights From the Upper Airway Epithelium

Respiratory virus infection is one of the major sources of exacerbation of chronic airway inflammatory diseases. These exacerbations are associated with high morbidity and even mortality worldwide. The current understanding on viral-induced exacerbations is that viral infection increases airway inflammation which aggravates disease symptoms. Recent advances in in vitro air-liquid interface 3D cultures, organoid cultures and the use of novel human and animal challenge models have evoked new understandings as to the mechanisms of viral exacerbations. In this review, we will focus on recent novel findings that elucidate how respiratory viral infections alter the epithelial barrier in the airways, the upper airway microbial environment, epigenetic modifications including miRNA modulation, and other changes in immune responses throughout the upper and lower airways. First, we reviewed the prevalence of different respiratory viral infections in causing exacerbations in chronic airway inflammatory diseases. Subsequently we also summarized how recent models have expanded our appreciation of the mechanisms of viral-induced exacerbations. Further we highlighted the importance of the virome within the airway microbiome environment and its impact on subsequent bacterial infection. This review consolidates the understanding of viral induced exacerbation in chronic airway inflammatory diseases and indicates pathways that may be targeted for more effective management of chronic inflammatory diseases.

The non-antibiotic macrolide EM900 attenuates HDM and poly(I:C)-induced airway inflammation with inhibition of macrophages in a mouse model

OBJECTIVE

Macrolides have been reported to reduce the exacerbation of severe asthma. The aim of this study was to clarify the effects and mechanisms of EM900, a non-antibiotic macrolide, on allergic airway inflammation.

METHODS

Mice were sensitized and challenged by house dust mite (HDM), then exposed to polyinosinic-polycytidylic acid (poly(I:C)) as a model of asthma complicated with viral infection. Mice were administered with EM900. Airway inflammation was assessed from inflammatory cells in bronchoalveolar lavage fluid (BALF) and cytokines in lung tissues. Lung interstitial macrophages were counted by flow cytometry. Cytokine production, phosphorylation of NF-κB, and p38 in macrophages were examined by ELISA and western blotting.

RESULTS

Counts of cells in BALF and concentrations of IL-13, IL-5, RANTES, IL-17A, and MIP-2 were significantly decreased by EM900 compared to those without EM900. Percentages of lung interstitial macrophages were significantly decreased with EM900. Concentrations of IL-6, RANTES, and MIP-2 induced by HDM and poly(I:C) were significantly suppressed by EM900 through the suppression of NF-κB and p38 phosphorylation in macrophages.

CONCLUSIONS

HDM and poly(I:C)-induced airway inflammation is attenuated by EM900 with the inhibition of lung interstitial macrophages. Clinical use of EM900 is expected, because EM900 has inhibitory effects against airway inflammation without inducing bacterial drug resistance.

Identification of a Novel Inhibitor of Human Rhinovirus Replication and Inflammation in Airway Epithelial Cells

Human rhinovirus (RV), the major cause of the common cold, triggers the majority of acute airway exacerbations in patients with asthma and chronic obstructive pulmonary disease. Nitric oxide, and the related metabolite S-nitrosoglutathione, are produced in the airway epithelium via nitric oxide synthase (NOS) 2 and have been shown to function in host defense against RV infection. We hypothesized that inhibitors of the S-nitrosoglutathione-metabolizing enzyme, S-nitrosoglutathione reductase (GSNOR), might potentiate the antiviral properties of airway-derived NOS2. Using in vitro models of RV-A serotype 16 (RV-A16) and mNeonGreen-H1N1pr8 infection of human airway epithelial cells, we found that treatment with a previously characterized GSNOR inhibitor (4-[[2-[[(3-cyanophenyl)methyl]thio]-4-oxothieno-[3,2-d]pyrimidin-3(4H)-yl]methyl]-benzoic acid; referred to as C3m) decreased RV-A16 replication and expression of downstream proinflammatory and antiviral mediators (e.g., RANTES [regulated upon activation, normal T cell expressed and secreted], CXCL10, and Mx1), and increased Nrf2 (nuclear factor erythroid 2-related factor 2)-dependent genes (e.g., SQSTM1 and TrxR1). In contrast, C3m had no effect on influenza virus H1N1pr8 replication. Moreover, a structurally dissimilar GSNOR inhibitor (N6022) did not alter RV replication, suggesting that the properties of C3m may be specific to rhinovirus owing to an off-target effect. Consistent with this, C3m antiviral effects were not blocked by either NOS inhibition or GSNOR knockdown but appeared to be mediated by reduced intercellular adhesion molecule 1 transcription and increased shedding of soluble intercellular adhesion molecule 1 protein. Collectively these data show that C3m has novel antirhinoviral properties that may synergize with, but are unrelated to, its GSNOR inhibitor activity.

Asthma exacerbation related to viral infections: An up to date summary

Asthma exacerbation can be a major life threatening event. Viruses have been pinned as the cause behind the vast majority of these exacerbations. The purpose of this short review is to explore the mechanisms behind these exacerbations, focusing mostly on viral infections as triggers. We will also be discussing the phenotypes prone to asthma exacerbation, the pathophysiology of viral induced asthma and ventilation patterns of asthmatic lungs. This manuscript will assist primary care physicians in delineating the proper pathophysiology of the disease as well as the management.

Acute Severe Asthma in Adolescent and Adult Patients: Current Perspectives on Assessment and Management

Asthma is a chronic airway inflammatory disease that is associated with variable expiratory flow, variable respiratory symptoms, and exacerbations which sometimes require hospitalization or may be fatal. It is not only patients with severe and poorly controlled asthma that are at risk for an acute severe exacerbation, but this has also been observed in patients with otherwise mild or moderate asthma. This review discusses current aspects on the pathogenesis and pathophysiology of acute severe asthma exacerbations and provides the current perspectives on the management of acute severe asthma attacks in the emergency department and the intensive care unit.

Genetic variants in 17q12-21 locus and childhood asthma in Brazil: Interaction with Varicella zoster virus seropositivity

BACKGROUND

Asthma is a complex disease with worldwide public health relevance, is related to environmental causes and a genetic predisposition. The chromosomal 17q12-21 locus has been consistently demonstrated to be associated with asthma risk. The effects of variants in the 17q12-21 locus on childhood asthma were first identified in a genome wide- association study. Since that time, those findings have been replicated in different populations but not in South American populations.

OBJECTIVE

This study aimed to investigate the role of variants in the 17q12-21 locus on asthma in a sample of Brazilian children.

METHODS

This was a cross-sectional study conducted on a cohort of 1247 children. These analyses used 50 Single Nucleotide Variants (SNVs) in the 17q12-21 locus were genotyped as part of a genome wide association study (GWAS).

RESULTS

Four SNVs (rs4065275, rs12603332, rs73985228 and rs77777702) were associated with childhood asthma. The rs73985228 exhibited the strongest association across the different genetic models (OR, 95%CI 2.8, 1.44-3.21, p < 0.01). In an analysis that was stratified by atopy, two SNVs (rs73985228 and rs2715555) were found to be associated with atopic and non-atopic asthma. For the first time, we observed a significant interaction with seropositivity for the Varicella zoster virus (for rs4065275, p = 0.02, and for rs12603332, p = 0.04); i.e., the association was found in those who were seropositive but not in those who were seronegative for this virus.

CONCLUSIONS

We confirmed the associations of variants in the 17q12-21 locus with atopic and non-atopic asthma and identified an interaction with seropositivity for the Varicella zoster virus.

Dual mechanism of action of T2 inhibitor therapies in virally induced exacerbations of asthma: evidence for a beneficial counter-regulation

Biological agents such as omalizumab and monoclonal antibodies (mAbs) that inhibit type 2 (T2) immunity significantly reduce exacerbations, which are mainly due to viral infections, when added to inhaled corticosteroids in patients with severe asthma. The mechanisms for the therapeutic benefit of T2 inhibitors in reducing virally induced exacerbations, however, remain to be fully elucidated. Pre-clinical and clinical evidence supports the existence of a close counter-regulation of the high-affinity IgE receptor and interferon (IFN) pathways, and a potential dual mechanism of action and therapeutic benefit for omalizumab and other T2 inhibitors that inhibit IgE activity, which may enhance the prevention and treatment of virally induced asthma exacerbations. Similar evidence regarding some novel T2 inhibitor therapies, including mAbs and small-molecule inhibitors, suggests that such a dual mechanism of action with enhancement of IFN production working through non-IgE pathways might also exist. The specific mechanisms for this dual effect could be related to the close counter-regulation between T2 and T1 immune pathways, and potential key underlying mechanisms are discussed. Further basic research and better understanding of these underlying counter-regulatory mechanisms could provide novel therapeutic targets for the prevention and treatment of virally induced asthma exacerbations, as well as T2- and non-T2-driven asthma. Future clinical research should examine the effects of T2 inhibitors on IFN responses and other T1 immune pathways, in addition to any effects on the frequency and severity of viral and other infections and related exacerbations in patients with asthma as a priority.

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.

Polymorphisms in the promoter region of IL10 gene are associated with virus etiology of infant bronchiolitis

BACKGROUND

Bronchiolitis is the most common infection leading to hospitalization in infancy. Interleukin-10 (IL-10) is an anti-inflammatory cytokine, and in our previous study, IL10 gene rs1800896 (- 1082A/G) polymorphism was associated with viral etiology of infant bronchiolitis. The objective of this study was to evaluate the associations between IL10 single nucleotide polymorphisms (SNPs) at rs1800890 (- 3575A/T), rs1800871 (- 819C/T) or rs1800872 (- 592C/A) either alone or combined with the SNP at rs1800896 (- 1082G/A), and the etiology and severity of infant bronchiolitis.

METHODS

Data on four IL10 SNPs were available from 135 full-term infants, hospitalized for bronchiolitis at age less than 6 months, and from 378 to 400 controls. Viral etiology was studied, and oxygen support, feeding support and the length of stay in hospital were recorded during bronchiolitis hospitalization.

RESULTS

Infants with rhinovirus bronchiolitis had the IL10 rs1800890 variant AT or TT genotype less often (18.2%) than controls (63.3%, P = 0.03), and likewise, had the IL10 rs1800896 variant AG or GG genotype less often (27.3%) than controls (65.5%, P = 0.009). Twenty-eight infants with bronchiolitis had the variant-variant G_rs1800896T_rs1800890 haplotype, and none of them had rhinovirus infection. The IL10 rs1800871 or rs1800872 genotypes showed no associations with viruses. No association was found between any genotypes and bronchiolitis severity measures.

CONCLUSION

IL10 rs1800890 and rs1800896 polymorphisms differed between infants with rhinovirus bronchiolitis and controls, but not between infants with respiratory syncytial virus bronchiolitis and controls.

Influence of viral infection on the relationships between airway cytokines and lung function in asthmatic children

BACKGROUND

Few longitudinal studies examine inflammation and lung function in asthma. We sought to determine the cytokines that reduce airflow, and the influence of respiratory viral infections on these relationships.

METHODS

Children underwent home collections of nasal lavage during scheduled surveillance periods and self-reported respiratory illnesses. We studied 53 children for one year, analyzing 392 surveillance samples and 203 samples from 85 respiratory illnesses. Generalized estimated equations were used to evaluate associations between nasal lavage biomarkers (7 mRNAs, 10 proteins), lung function and viral infection.

RESULTS

As anticipated, viral infection was associated with increased cytokines and reduced FVC and FEV1. However, we found frequent and strong interactions between biomarkers and virus on lung function. For example, in the absence of viral infection, CXCL10 mRNA, MDA5 mRNA, CXCL10, IL-4, IL-13, CCL4, CCL5, CCL20 and CCL24 were negatively associated with FVC. In contrast, during infection, the opposite relationship was frequently found, with IL-4, IL-13, CCL5, CCL20 and CCL24 levels associated with less severe reductions in both FVC and FEV1.

CONCLUSIONS

In asthmatic children, airflow obstruction is driven by specific pro-inflammatory cytokines. In the absence of viral infection, higher cytokine levels are associated with decreasing lung function. However, with infection, there is a reversal in this relationship, with cytokine abundance associated with reduced lung function decline. While nasal samples may not reflect lower airway responses, these data suggest that some aspects of the inflammatory response may be protective against viral infection. This study may have ramifications for the treatment of viral-induced asthma exacerbations.

Impact of community respiratory viral infections in urban children with asthma

Background

Upper respiratory tract viral infections cause asthma exacerbations in children. However, the impact of natural colds on children with asthma in the community, particularly in the high-risk urban environment, is less well defined.

Objective

We hypothesized that children with high-symptom upper respiratory viral infections have reduced airway function and greater respiratory tract inflammation than children with virus-positive low-symptom illnesses or virus-negative upper respiratory tract symptoms.

Methods

We studied 53 children with asthma from Detroit, Michigan, during scheduled surveillance periods and self-reported respiratory illnesses for 1 year. Symptom score, spirometry, fraction of exhaled nitric oxide (FeNO), and nasal aspirate biomarkers, and viral nucleic acid and rhinovirus (RV) copy number were assessed.

Results

Of 658 aspirates collected, 22.9% of surveillance samples and 33.7% of respiratory illnesses were virus-positive. Compared with the virus-negative asymptomatic condition, children with severe colds (symptom score ≥5) showed reduced forced expiratory flow at 25% to 75% of the pulmonary volume (FEF_25%-75%), higher nasal messenger RNA expression of C-X-C motif chemokine ligand (CXCL)-10 and melanoma differentiation-associated protein 5, and higher protein abundance of CXCL8, CXCL10 and C-C motif chemokine ligands (CCL)-2, CCL4, CCL20, and CCL24. Children with mild (symptom score, 1-4) and asymptomatic infections showed normal airway function and fewer biomarker elevations. Virus-negative cold-like illnesses demonstrated increased FeNO, minimal biomarker elevation, and normal airflow. The RV copy number was associated with nasal chemokine levels but not symptom score.

Conclusion

Urban children with asthma with high-symptom respiratory viral infections have reduced FEF_25%-75% and more elevations of nasal biomarkers than children with mild or symptomatic infections, or virus-negative illnesses.

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.

Effects of human rhinovirus on epithelial barrier integrity and function in children with asthma

BACKGROUND

Bronchial epithelial tight junctions (TJ) have been extensively assessed in healthy airway epithelium. However, no studies have yet assessed the effect of human rhinovirus (HRV) infection on the expression and resultant barrier function in epithelial tight junctions (TJ) in childhood asthma.

OBJECTIVES

To investigate the impact of HRV infection on airway epithelial TJ expression and barrier function in airway epithelial cells (AECs) of children with and without asthma. Furthermore, to test the hypothesis that barrier integrity and function is compromised to a greater extent by HRV in AECs from asthmatic children.

METHODS

Primary AECs were obtained from children with and without asthma, differentiated into air-liquid interface (ALI) cultures and infected with rhinovirus. Expression of claudin-1, occludin and zonula occluden-1 (ZO-1) was assessed via qPCR, immunocytochemistry (ICC), in-cell western (ICW) and confocal microscopy. Barrier function was assessed by transepithelial electrical resistance (TER; R_T ) and permeability to fluorescent dextran.

RESULTS

Basal TJ gene expression of claudin-1 and occludin was significantly upregulated in asthmatic children compared to non-asthmatics; however, no difference was seen with ZO-1. Interestingly, claudin-1, occludin and ZO-1 protein expression was significantly reduced in AEC of asthmatic children compared to non-asthmatic controls suggesting possible post-transcriptional inherent differences. HRV infection resulted in a transient dissociation of TJ and airway barrier integrity in non-asthmatic children. Although similar dissociation of TJ was observed in asthmatic children, a significant and sustained reduction in TJ expression concurrent with both a significant decrease in TER and an increase in permeability in asthmatic children was observed.

CONCLUSION

This study demonstrates novel intrinsic differences in TJ gene and protein expression between AEC of children with and without asthma. Furthermore, it correlates directly the relationship between HRV infection and the resultant dissociation of epithelial TJ that causes a continued altered barrier function in children with asthma.

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.

Detection of pathogens by real-time PCR in adult patients with acute exacerbation of bronchial asthma

BACKGROUND

Respiratory tract infection is a major cause of acute exacerbation of bronchial asthma (AEBA). Although recent findings suggest that common bacteria are causally associated with AEBA, a comprehensive epidemiologic analysis of infectious pathogens including common/atypical bacteria and viruses in AEBA has not been performed. Accordingly, we attempted to detect pathogens during AEBA by using real-time polymerase chain reaction (PCR) in comparison to conventional methods.

METHODS

We prospectively enroled adult patients with AEBA from August 2012 to March 2014. Infectious pathogens collected in nasopharyngeal swab and sputum samples were examined in each patient by conventional methods and real-time PCR, which can detect 6 bacterial and 11 viral pathogens. The causal association of these pathogens with AEBA severity and their frequency of monthly distribution were also examined.

RESULTS

Among the 64 enroled patients, infectious pathogens were detected in 49 patients (76.6%) using real-time PCR and in 14 patients (21.9%) using conventional methods (p < 0.001). Real-time PCR detected bacteria in 29 patients (45.3%) and respiratory viruses in 28 patients (43.8%). Haemophilus influenzae was the most frequently detected microorganism (26.6%), followed by rhinovirus (15.6%). Influenza virus was the significant pathogen associated with severe AEBA. Moreover, AEBA occurred most frequently during November to January.

CONCLUSIONS

Real-time PCR was more useful than conventional methods to detect infectious pathogens in patients with AEBA. Accurate detection of pathogens with real-time PCR may enable the selection of appropriate anti-bacterial/viral agents as a part of the treatment for AEBA.

Effects of procalcitonin-guided treatment on antibiotic use and need for mechanical ventilation in patients with acute asthma exacerbation: Meta-analysis of randomized controlled trials

OBJECTIVE

The primary outcome was to determine whether serum procalcitonin-guided antibiotic therapy can reduce antibiotic exposure in patients with an acute exacerbation of asthma presenting to the primary care facility or emergency department, or during hospital admission. The secondary outcome was the need for mechanical ventilation.

METHODS

An extensive literature search was performed to identify randomized controlled clinical trials (published in English) that compared serum procalcitonin-guided antibiotic therapy versus antibiotic use according to physician's discretion for adult participants with mild, moderate, or severe acute asthma exacerbations.

RESULTS

Four randomized controlled trials evaluating 457 patients were included in this meta-analysis, with significant homogeneity observed among these studies. Procalcitonin-based protocols decreased antibiotic prescriptions (relative risk 0.58, 95% confidence interval 0.50-0.67). The conclusion regarding the difference between the two groups in the need for mechanical ventilation (relative risk 1.10, 95% confidence interval 0.62-1.94) was guarded due to inadequate power and the potential for type II error. The overall quality of evidence was also limited by the lack of double-blinding.

CONCLUSIONS

These data suggest a potential benefit for the use of serum procalcitonin in guiding antibiotic therapy in patients with an acute asthma exacerbation and advocates the need for more randomized controlled trials.

Toll-like Receptor 7 Is Reduced in Severe Asthma and Linked to an Altered MicroRNA Profile

RATIONALE

Asthma is one of the most common chronic diseases worldwide, and individuals with severe asthma experience recurrent exacerbations. Exacerbations are predominantly viral associated and have been linked to defective airway IFN responses. Ascertaining the molecular mechanisms underlying this deficiency is a major research goal to identify new therapeutic targets.

OBJECTIVES

We investigated the hypothesis that reduced Toll-like receptor 7 (TLR7)-derived signaling drove the impaired IFN responses to rhinovirus by asthmatic alveolar macrophages (AMs); the molecular mechanisms underlying this deficiency were explored.

METHODS

AMs were recovered from bronchoalveolar lavage from healthy subjects and patients with severe asthma. Expression of pattern-recognition receptors and microRNAs was evaluated by quantitative polymerase chain reaction and Western blotting. A TLR7-luciferase reporter construct was created to evaluate binding of microRNAs to the 3' untranslated region of TLR7. IFN production was measured by quantitative polymerase chain reaction and ELISA.

MEASUREMENTS AND MAIN RESULTS

The expression of TLR7 was significantly reduced in severe asthma AMs and was associated with reduced rhinovirus and imiquimod-induced IFN responses by these cells compared with healthy AMs. Severe asthma AMs also expressed increased levels of three microRNAs, which we showed were able to directly reduce TLR7 expression. Ex vivo knockdown of these microRNAs restored TLR7 expression with concomitant augmentation of virus-induced IFN production.

CONCLUSIONS

In severe asthma, TLR7 deficiency drives impaired innate immune responses to virus by AMs. Blocking a group of microRNAs that are up-regulated in these cells can restore antiviral innate responses, providing a novel approach for therapy in asthma.

Infection-mediated asthma: etiology, mechanisms and treatment options, with focus on Chlamydia pneumoniae and macrolides

Asthma is a chronic respiratory disease characterized by reversible airway obstruction and airway hyperresponsiveness to non-specific bronchoconstriction agonists as the primary underlying pathophysiology. The worldwide incidence of asthma has increased dramatically in the last 40 years. According to World Health Organization (WHO) estimates, over 300 million children and adults worldwide currently suffer from this incurable disease and 255,000 die from the disease each year. It is now well accepted that asthma is a heterogeneous syndrome and many clinical subtypes have been described. Viral infections such as respiratory syncytial virus (RSV) and human rhinovirus (hRV) have been implicated in asthma exacerbation in children because of their ability to cause severe airway inflammation and wheezing. Infections with atypical bacteria also appear to play a role in the induction and exacerbation of asthma in both children and adults. Recent studies confirm the existence of an infectious asthma etiology mediated by Chlamydia pneumoniae (CP) and possibly by other viral, bacterial and fungal microbes. It is also likely that early-life infections with microbes such as CP could lead to alterations in the lung microbiome that significantly affect asthma risk and treatment outcomes. These infectious microbes may exacerbate the symptoms of established chronic asthma and may even contribute to the initial development of the clinical onset of the disease. It is now becoming more widely accepted that patterns of airway inflammation differ based on the trigger responsible for asthma initiation and exacerbation. Therefore, a better understanding of asthma subtypes is now being explored more aggressively, not only to decipher pathophysiologic mechanisms but also to select treatment and guide prognoses. This review will explore infection-mediated asthma with special emphasis on the protean manifestations of CP lung infection, clinical characteristics of infection-mediated asthma, mechanisms involved and antibiotic treatment outcomes.

Azithromycin for Acute Exacerbations of Asthma : The AZALEA Randomized Clinical Trial

IMPORTANCE

Guidelines recommend against antibiotic use to treat asthma attacks. A study with telithromycin reported benefit, but adverse reactions limit its use.

OBJECTIVE

To determine whether azithromycin added to standard care for asthma attacks in adults results in clinical benefit.

DESIGN, SETTING, AND PARTICIPANTS

The Azithromycin Against Placebo in Exacerbations of Asthma (AZALEA) randomized, double-blind, placebo-controlled clinical trial, a United Kingdom-based multicenter study in adults requesting emergency care for acute asthma exacerbations, ran from September 2011 to April 2014. Adults with a history of asthma for more than 6 months were recruited within 48 hours of presentation to medical care with an acute deterioration in asthma control requiring a course of oral and/or systemic corticosteroids.

INTERVENTIONS

Azithromycin 500 mg daily or matched placebo for 3 days.

MAIN OUTCOMES AND MEASURES

The primary outcome was diary card symptom score 10 days after randomization, with a hypothesized treatment effect size of -0.3. Secondary outcomes were diary card symptom score, quality-of-life questionnaires, and lung function changes, all between exacerbation and day 10, and time to a 50% reduction in symptom score.

RESULTS

Of 4582 patients screened at 31 centers, 199 of a planned 380 were randomized within 48 hours of presentation. The major reason for nonrecruitment was receipt of antibiotics (2044 [44.6%] screened patients). Median time from presentation to drug administration was 22 hours (interquartile range, 14-28 hours). Exacerbation characteristics were well balanced across treatment arms and centers. The primary outcome asthma symptom scores were mean (SD), 4.14 (1.38) at exacerbation and 2.09 (1.71) at 10 days for the azithromycin group and 4.18 (1.48) and 2.20 (1.51) for the placebo group, respectively. Using multilevel modeling, there was no significant difference in symptom scores between azithromycin and placebo at day 10 (difference, -0.166; 95% CI, -0.670 to 0.337), nor on any day between exacerbation and day 10. No significant between-group differences were observed in quality-of-life questionnaires or lung function between exacerbation and day 10, or in time to 50% reduction in symptom score.

CONCLUSIONS AND RELEVANCE

In this randomized population, azithromycin treatment resulted in no statistically or clinically significant benefit. For each patient randomized, more than 10 were excluded because they had already received antibiotics.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01444469.

Generation of IL10 and TGFB1 coexpressed mice displaying resistance to ovalbumin-induced asthma

Asthma is a common chronic inflammatory disease in the airways with wide prevalence, and it is thought to be caused by the combinational factors in environment and genetics. A large body of studies has suggested that cell immunity played a vital role in regulating the airway hyperreactivity (AHR) and inflammation. Therefore, we here developed a mouse model of asthma by microinjecting the pronucleus with a vector spontaneously coding human IL10 and TGFB1 gene to explore the possible interaction between these two potent molecules during asthma progression. From the total 35 newborn mice, we successfully obtained 3 founders expressing exogenous genes. In the transgenic mice, we observed profoundly enhanced expression of IL10 and TGFB1. In the condition of ovalbumin challenge, transgenic mice displayed a 1.9-fold higher MCh50 score than wild-type counterparts, indicating reminiscent AHR. Meanwhile, a three-fold decrease of cell counts in bronchoalveolar lavage fluid (BALF) was recorded as well. These results suggested that IL10 and TGFB1 cooperatively protected the respiratory system in response to antigenic stimulus. To interrogate the respective behaviors of the two genes, we quantified the expression of downstream genes in IL10 signaling or TGFB1 signaling. We observed that the examined genes in IL10 signaling were significantly repressed, especially IL5, which showed 5.4-fold decreased expression. Most genes were not altered in TGFB1 signaling, and the production of endogenous TGFB1 was significantly inhibited. These evidences collectively proved that the activation of IL0 and TGFB1 protected the host from antigen-induced asthma, possibly through IL10 signaling. This study shed some light on the modulations of IL10 and TGFB1, and related networks to asthma progression.

Tbet Deficiency Causes T Helper Cell Dependent Airways Eosinophilia and Mucus Hypersecretion in Response to Rhinovirus Infection

Current understanding of adaptive immune, particularly T cell, responses to human rhinoviruses (RV) is limited. Memory T cells are thought to be of a primarily T helper 1 type, but both T helper 1 and T helper 2 memory cells have been described, and heightened T helper 2/ lessened T helper 1 responses have been associated with increased RV-induced asthma exacerbation severity. We examined the contribution of T helper 1 cells to RV-induced airways inflammation using mice deficient in the transcription factor T-Box Expressed In T Cells (Tbet), a critical controller of T helper 1 cell differentiation. Using flow cytometry we showed that Tbet deficient mice lacked the T helper 1 response of wild type mice and instead developed mixed T helper 2/T helper 17 responses to RV infection, evidenced by increased numbers of GATA binding protein 3 (GATA-3) and RAR-related orphan receptor gamma t (RORγt), and interleukin-13 and interleukin-17A expressing CD4+ T cells in the lung. Forkhead box P3 (FOXP3) and interleukin-10 expressing T cell numbers were unaffected. Tbet deficient mice also displayed deficiencies in lung Natural Killer, Natural Killer T cell and γδT cell responses, and serum neutralising antibody responses. Tbet deficient mice exhibited pronounced airways eosinophilia and mucus production in response to RV infection that, by utilising a CD4+ cell depleting antibody, were found to be T helper cell dependent. RV induction of T helper 2 and T helper 17 responses may therefore have an important role in directly driving features of allergic airways disease such as eosinophilia and mucus hypersecretion during asthma exacerbations.

Pathogenesis of Viral Infection in Exacerbations of Airway Disease

Chronic airway diseases are a significant cause of morbidity and mortality worldwide, and their prevalence is predicted to increase in the future. Respiratory viruses are the most common cause of acute pulmonary infection, and there is clear evidence of their role in acute exacerbations of inflammatory airway diseases such as asthma and chronic obstructive pulmonary disease. Studies have reported impaired host responses to virus infection in these diseases, and a better understanding of the mechanisms of these abnormal immune responses has the potential to lead to the development of novel therapeutic targets for virus-induced exacerbations. The aim of this article is to review the current knowledge regarding the role of viruses and immune modulation in acute exacerbations of chronic pulmonary diseases and to discuss exciting areas for future research and novel treatments.

A novel immunomodulatory function of neutrophils on rhinovirus-activated monocytes in vitro

Background

Rhinovirus (RV) infections are the major precipitant of asthma exacerbations. While neutrophilic lung inflammation occurs during such infections, its role remains unclear. Neutrophilic inflammation is associated with increased asthma severity and steroid refractory disease. Neutrophils are vital for controlling infections but also have immunomodulatory functions. Previously, we found that neutrophils respond to viral mimetics but not replication competent RV. We aimed to investigate if neutrophils are activated and/or modulate immune responses of monocytes during RV16 infection.

Methods

Primary human monocytes and autologous neutrophils were cocultured with or without RV16, in direct contact or separated by transwells. RV16-stimulated monocytes were also exposed to lysed neutrophils, neutrophil membrane components or soluble neutrophil intracellular components. Interleukin 6 (IL-6) and C-X-C motif (CXC)L8 mRNA and proteins were measured by quantitative PCR and ELISA at 24 hours.

Results

RV16 induced IL-6 and CXCL8 in monocytes, but not neutrophils. RV16-induced IL-6 and CXCL8 from monocytes was reduced in the presence of live neutrophils. Transwell separation abolished the inhibitory effects. Lysed neutrophils inhibited RV16-induced IL-6 and CXCL8 from monocytes. Neutrophil intracellular components alone effectively inhibited RV16-induced monocyte-derived IL-6 and CXCL8. Neutrophil intracellular components reduced RV16-induced IL-6 and CXCL8 mRNA in monocytes.

Conclusions

Cell contact between monocytes and neutrophils is required, and preformed neutrophil mediator(s) are likely to be involved in the suppression of cytokine mRNA and protein production. This study demonstrates a novel regulatory function of neutrophils on RV-activated monocytes in vitro, challenging the paradigm that neutrophils are predominantly proinflammatory.

Strategies targeting the IL-4/IL-13 axes in disease

IL-4 and IL-13 are pleiotropic Th2 cytokines produced by a wide variety of different cell types and responsible for a broad range of biology and functions. Physiologically, Th2 cytokines are known to mediate host defense against parasites but they can also trigger disease if their activities are dysregulated. In this review we discuss the rationale for targeting the IL-4/IL-13 axes in asthma, atopic dermatitis, allergic rhinitis, COPD, cancer, inflammatory bowel disease, autoimmune disease and fibrotic disease as well as evaluating the associated clinical data derived from blocking IL-4, IL-13 or IL-4 and IL-13 together.

Holding the Inflammatory System in Check: TLRs and Their Targeted Therapy in Asthma

Inflammation is a complex biological response to detrimental stimuli and can be a double-edged sword. Inflammation plays a protective role in removing pathogenic factors, but dysregulated inflammation is associated with several major fatal diseases such as asthma, cancer, and cardiovascular diseases. Asthma is a complex heterogenous disease caused by genetic and environmental factors. TLRs are the primary proteins associated with the innate and adaptive immune responses to these fatal factors and play an important role in recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), which initiates the downstream immune response. Due to the complex TLRs cascade and nowadays unsuccessful control in asthma, new studies are focused on TLRs and other potential targets in TLR cascade to minimize airway inflammation.

Advances in the treatment of virus-induced asthma

Viral exacerbations continue to represent the major burden in terms of morbidity, mortality and health care costs associated with asthma. Those at greatest risk for acute asthma are those with more severe airways disease and poor asthma control. It is this group with established asthma in whom acute exacerbations triggered by virus infections remain a serious cause of increased morbidity. A range of novel therapies are emerging to treat asthma and in particular target this group with poor disease control, and in most cases their efficacy is now being judged by their ability to reduce the frequency of acute exacerbations. Critical for the development of new treatment approaches is an improved understanding of virus-host interaction in the context of the asthmatic airway. This requires research into the virology of the disease in physiological models in conjunction with detailed phenotypic characterisation of asthma patients to identify targets amenable to therapeutic intervention.

Presence of rhinovirus in the respiratory tract of adolescents and young adults with asthma without symptoms of infection

Background

Viral respiratory infections have been associated with up to 80% of wheezing episodes and asthma exacerbations. However, studies on the role of these viruses in asthmatic patients in the interval between exacerbations are sparse. This study aimed to determine the presence of respiratory viruses, without symptoms of infection, in the airways of young asthmatics as compared to healthy controls.

Material and Methods

Patients 10–35 years of age with stable asthma and a group of healthy controls were analyzed regarding the presence of RNA from common respiratory viruses in nasopharyngeal aspirates by PCR. Self-reported asthma control and quality of life, fraction of exhaled nitric oxide (FeNO), spirometry, and bronchial responsiveness to methacholine were recorded. Blood samples were collected to assess IgE sensitisation and eosinophil cationic protein (ECP) levels.

Results

In 354 patients with asthma and 108 healthy controls, human rhinovirus (HRV) was the only virus detected (4.5% of asthmatics vs. 0.9% of controls; p = 0.08). HRV⁺ asthma patients had a higher degree of aeroallergen IgE sensitisation (median 37.7 vs. 10.4 kU_A/L, p = 0.04), and a tendency for higher levels of serum ECP (median 17.2 vs. 12.6 μg/L, p = 0.07), as compared to their HRV⁻ counterparts.

Conclusions

Absence of symptoms of respiratory tract infection notwithstanding, HRV seems to be more prevalent in the airways of adolescents and young adults with asthma and a high degree of aeroallergen IgE sensitisation than in controls. The presence of HRV seems also to be related to systemic eosinophilic inflammation despite ongoing treatment with inhaled corticosteroids.

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Cross-sectional study on adolescents and young adults with asthma and healthy controls.

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Common respiratory viruses examined in nasopharyngeal aspirates by PCR.

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Only rhinovirus detected in subjects without symptoms of respiratory tract infection.

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Prevalence of rhinovirus tended to be higher in asthmatics compared to controls.

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Presence of rhinovirus associated with high degree of aeroallergen IgE sensitisation.

The role of viral infections in exacerbations of chronic obstructive pulmonary disease and asthma

Asthma and chronic obstructive pulmonary disease (COPD) are major causes of global morbidity and mortality worldwide. The clinical course of both asthma and COPD are punctuated by the occurrence of exacerbations, acute events characterized by increased symptoms and airflow obstruction. Exacerbations contribute most of the morbidity, mortality and excess healthcare costs associated with both asthma and COPD. COPD and asthma exacerbations are frequently associated with respiratory virus infections and this has led to an intense research focus into the mechanisms of virus-induced exacerbations over the past decade. Current therapies are effective in reducing chronic symptoms but are less effective in preventing exacerbations, particularly in COPD. Understanding the mechanisms of virus-induced exacerbation will lead to the development of new targeted therapies that can reduce the burden of virus-induced exacerbations. In this review we discuss current knowledge of virus-induced exacerbations of asthma and COPD with a particular focus on mechanisms, human studies, virus-bacteria interactions and therapeutic advances.

Are respiratory viruses involved in preseasonal symptoms or severity in Japanese cedar pollinosis?

BACKGROUND

Respiratory virus infections are involved in asthma exacerbations. However, there are no reports of the relationship between respiratory virus infections and Japanese cedar pollinosis.

OBJECTIVE

We studied the relationship between respiratory viral infection and the appearance of preseasonal symptoms and the severity of seasonal symptoms in Japanese cedar pollinosis.

METHODS

In 36 patients with asthma and with no symptoms (PreAsyP) and 54 patients with asthma and with symptoms (PreSyP) before the cedar pollen shedding commenced (preseason), and 37 patients with mild-to-moderate severity (InMild/Mod) and 45 patients with severe to extreme severity (InSev/Ext) after cedar shedding commenced (in season), the occurrence of respiratory viruses and nasal smear cytology were examined.

RESULTS

In total, seven infections with respiratory viruses were detected among the subjects. Human rhinovirus (HRV) C infection was detected in one subject in each of the PreAsyP and PreSyP groups, and one HRVA infection occurred in the InMild/Mod group. In the InSev/Ext group, one HRVA, one HRVC, one respiratory syncytial virus, and one human metapneumovirus were detected. There was no significant difference in the rate of detection of viral infections between the PreAsyP and the PreSyP groups (p = 0.077), and between the InMild/Mod group and the InSev/Ext group (p = 0.24, Wilcoxon rank sum test). When cells types in nasal smears were identified and their abundance examined, the rate of neutrophilia in the subjects in the PreSyP group was 54%, which was statistically higher (p < 0.01) than the subjects in the PreAsyP group (25%). Interestingly, in the subjects in the InSev/Ext group, the proportion of eosinophils (40%) was larger (p < 0.05) than in the subjects in the InMild/Mod group (19%).

CONCLUSION

These results provided no evidence that respiratory virus infections contributed to preseasonal symptoms and severity in season of Japanese cedar pollinosis. Nasal neutrophilia was related to preseasonal symptoms, whereas nasal eosinophilia was related to severity of symptoms during the pollen season.

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.

Rhinovirus stimulated IFN-α production: how important are plasmacytoid DCs, monocytes and endosomal pH?

Human rhinovirus (HRV) infection is a major cause of asthma exacerbations, which appears to be linked to a defective innate immune response to infection. Although the type I interferons (IFN-α and IFN-β) have a critical role in protecting against most viral infections, the cells responsible for IFN production in response to HRV and the relative importance of pattern recognition receptors located in endosomes has not been fully elucidated. In the current study we demonstrate that, using intracellular flow cytometry, >90% of the IFN-α-producing cells in human blood mononuclear cells following HRV16 exposure are plasmacytoid dendritic cells, whereas monocytes and myeloid dendritic cells contribute only 10% and <1%, respectively, of the IFN-α production. Bafilomycin and chloroquine, agents that inhibit the function of endosomal toll-like receptors (TLRs), significantly reduced the capacity of TLR3-, TLR7- and TLR-9-stimulated cells to produce IFN-α and the IFN-induced chemokine CXCL10 (IP-10). In contrast, only bafilomycin (but not chloroquine) effectively suppressed HRV16-stimulated IFN-α and IP-10 production, whereas neither bafilomycin or chloroquine inhibited HRV16-stimulated interleukin-6 release. Attempts to block IFN-α production with commercially available TLR-specific oligonucleotides were unsuccessful due to major ‘off-target' effects. These findings suggest that among circulating haemopoietic cells, plasmacytoid dendritic cells and TLRs located within endosomes are critical for inducing efficient IFN-I production in response to HRVs.

Differential neutrophil activation in viral infections: Enhanced TLR-7/8-mediated CXCL8 release in asthma

Background and objective

Respiratory viral infections are a major cause of asthma exacerbations. Neutrophils accumulate in the airways and the mechanisms that link neutrophilic inflammation, viral infections and exacerbations are unclear. This study aims to investigate anti‐viral responses in neutrophils from patients with and without asthma and to investigate if neutrophils can be directly activated by respiratory viruses.

Methods

Neutrophils from peripheral blood from asthmatic and non‐asthmatic individuals were isolated and stimulated with lipopolysaccharide (LPS) (1 μg/mL), f‐met‐leu‐phe (fMLP) (100 nM), imiquimod (3 μg/mL), R848 (1.5 μg/mL), poly I:C (10 μg/mL), RV16 (multiplicity of infection (MOI)1), respiratory syncytial virus (RSV) (MOI1) or influenza virus (MOI1). Cell‐free supernatants were collected after 1 h of neutrophil elastase (NE) and matrix metalloproteinase (MMP)‐9 release, or after 24 h for CXCL8 release.

Results

LPS, fMLP, imiquimod and R848 stimulated the release of CXCL8, NE and MMP‐9 whereas poly I:C selectively induced CXCL8 release only. R848‐induced CXCL8 release was enhanced in neutrophils from asthmatics compared with non‐asthmatic cells (P < 0.01). RSV triggered the release of CXCL8 and NE from neutrophils, whereas RV16 or influenza had no effect.

Conclusion

Neutrophils release CXCL8, NE and MMP‐9 in response to viral surrogates with R848‐induced CXCL8 release being specifically enhanced in asthmatic neutrophils. Toll‐like receptor (TLR7/8) dysregulation may play a role in neutrophilic inflammation in viral‐induced exacerbations.

We aimed to investigate and compare neutrophil responses to bacterial compounds and viral mimetics as well as compare responses between people with and without asthma. We also investigated neutrophil responses to live respiratory viruses. Here we provide a novel comprehensive comparison showing differential and specific activation in innate immune cells.

See Editorial, page 10

The Effect of Viral Infection on Exhaled Nitric Oxide in Children with Acute Asthma Exacerbations

BACKGROUND

Fraction of exhaled nitric oxide (Feno) level is used as an aid in the diagnosis and management of chronic asthma. Its role in acute asthma remains to be studied.

OBJECTIVE

To determine whether Feno levels are elevated in children with asthma exacerbations compared with baseline, and whether there is a difference in Feno levels based on PCR positive (+) (respiratory virus isolated by PCR analysis) versus PCR negative (-) (respiratory virus not isolated by PCR analysis) status.

METHODS

Children with a previous Feno level measurement while stable and who presented to an urgent care facility with an asthma exacerbation were enrolled. Feno levels, spirometry, and nasal swabs for viral PCR were obtained at the time of the exacerbation and following a course of prednisone. Data were available on 66 children. Linear mixed models were used to regress the outcomes of interest (FEV1, FEV1/forced vital capacity, forced expiratory flow at 25% to 75% of forced vital capacity, and natural log Feno) on detected virus (yes/no), visit (baseline, exacerbation, follow-up), and the interaction between the detected virus and visit.

RESULTS

Compared with baseline, higher Feno values and lower lung function were found at the time of an exacerbation. A respiratory virus was detected in 59% of the exacerbations. The interaction between PCR (+) and PCR (-) groups and visit on log Feno was marginally significant (P = .07). There was no difference in log Feno between the PCR (+) and PCR (-) groups at baseline, while higher log Feno was found in the PCR (-) group at the time of exacerbation and following prednisone (P = .05 and .001, respectively).

CONCLUSIONS

Higher Feno concentration in PCR (-) exacerbations suggests an eosinophilic predominance in nonviral compared with viral exacerbations.

Incidence and Triggers of Asthma Exacerbations Attended in the Emergency Department as a Level of Care Indicator (ASMAB III, 2005 and ASMAB IV, 2011)

INTRODUCTION

The identification of asthma exacerbations (AE) seen in emergency departments and in the home is proposed as a parameter of asthma control and for monitoring environmental triggers.

PATIENTS AND METHODS

All AEs seen in 2005 and 2011 in the reference hospital of the region and in the patients' homes by the Emergency Medical Services were identified.

RESULTS

The incidence of AE was 1.93/10(6)inhabitants/day during 2005, and 2/10(6)inhabitants/day in 2011. The most common triggers were slow onset common cold of more than 24h duration in 104/219 (47%) AEs in 2005 and 107/220 (49%) in 2011; prior bronchial symptoms with cough, expectoration and fever were recorded in 41/219 (19%) in 2005 and in 57/220 (26%) AEs in 2011. In total, 49% (2005) and 74% (2011) of the AEs had onset more than 24h before admission.

CONCLUSIONS

No significant differences were observed in the rate of attendance in the emergency department due to AE between 2005 and 2011. The most common triggers were common cold and bronchial symptoms with expectoration and fever. AE had begun more than 24h previously in at least half of cases. These findings appear to suggest that there may be a scope for improvement in the outpatient care of the asthmatic patient.

The impact of asthma exacerbations and preventive strategies

OBJECTIVE

To review the pathophysiologic mechanisms underlying asthma exacerbations, the impact of exacerbations, and both current and future treatment strategies to establish asthma control and reduce the risk of future exacerbations.

RESEARCH DESIGN AND METHODS

Relevant adult data were identified via PubMed, with additional references obtained by reviewing bibliographies from selected articles.

RESULTS

Asthma exacerbations or 'attacks' are acute episodes of progressive worsening of symptoms which occur in patients with all degrees of asthma severity and are an important cause of morbidity and mortality. For patients, these asthma attacks constitute a considerable part of the disease burden in terms of both personal suffering and economic impact. Exacerbations are characterized in part by decreases in expiratory flow or lung function. The pathophysiologic mechanism underlying these changes is likely to be different depending on the specific asthma phenotype. Asthma exacerbations are commonly initiated by upper respiratory tract infections and/or environmental allergens, although there are other known factors which increase the risk of a patient developing exacerbations, such as cigarette smoking. Establishing asthma control and reducing the risk of future exacerbations is the main goal of asthma treatment. Inhaled corticosteroids alone or in combination with long-acting β2-agonists, in addition to other step-up strategies such as leukotriene receptor antagonists and theophylline, are recommended. The anti-immunoglobulin E monoclonal antibody omalizumab should also be considered in difficult-to-treat allergic asthma.

CONCLUSIONS

Despite the currently available treatments, many patients with asthma remain symptomatic and experience exacerbations regardless of disease severity. New therapies, including long-acting anticholinergics, anti-cytokines, and chemoattractant receptor-homologous molecules, are under investigation with some promising results. In addition to increased education and use of self-management plans, these novel therapies are essential to help improve asthma control and reduce exacerbation risk.