Rhinovirus infection and house dust mite exposure synergize in inducing bronchial epithelial cell interleukin-8 release

Addressing adverse synergies between chemical and biological pollutants at schools-The 'SynAir-G' hypothesis

While the number and types of indoor air pollutants is rising, much is suspected but little is known about the impact of their potentially synergistic interactions, upon human health. Gases, particulate matter, organic compounds but also allergens and viruses, fall within the 'pollutant' definition. Distinct populations, such as children and allergy and asthma sufferers are highly susceptible, while a low socioeconomic background is a further susceptibility factor; however, no specific guidance is available. We spend most of our time indoors; for children, the school environment is of paramount importance and potentially amenable to intervention. The interactions between some pollutant classes have been studied. However, a lot is missing with respect to understanding interactions between specific pollutants of different classes in terms of concentrations, timing and sequence, to improve targeting and upgrade standards. SynAir-G is a European Commission-funded project aiming to reveal and quantify synergistic interactions between different pollutants affecting health, from mechanisms to real life, focusing on the school setting. It will develop a comprehensive and responsive multipollutant monitoring system, advance environmentally friendly interventions, and disseminate the generated knowledge to relevant stakeholders in accessible and actionable formats. The aim of this article it to put forward the SynAir-G hypothesis, and describe its background and objectives.

Environmental Interventions for Asthma

Exposure and sensitization to environmental factors play a fundamental role in asthma development and is strongly associated with asthma morbidity. While hereditary factors are critical determinants of asthma, exposures to environmental factors are implicated in the phenotypic expression of asthma and have been strongly associated in the risk of its development. Significant interest has thus been geared toward potentially modifiable environmental exposures which may lead to the development of asthma. Allergen exposure, in particular indoor allergens, plays a significant role in the pathogenesis of asthma, and remediation is a primary component of asthma management. In the home, multifaceted and multitargeted environmental control strategies have been shown to reduce home exposures and improve asthma outcomes. In addition to the home environment, assessment of the school, daycare, and workplace environments of patients with asthma is necessary to ensure appropriate environmental control measures in conjunction with medical care. This article will discuss the role of the environment on asthma, review targeted environmental therapy, and examine environmental control measures to suppress environmental exposures in the home and school setting.

The role of environmental allergen control in the management of asthma

Allergen exposure may exacerbate asthma symptoms in sensitized patients. Allergen reduction or avoidance measures have been widely utilized; however, there is ongoing controversy on the effectiveness of specific allergen control measures in the management of children with asthma. Often, allergen avoidance strategies are not recommended by guidelines because they can be complex or burdensome, although individual patients may benefit. Here we explore the potential for intervention against exposure to the major allergens implicated in asthma (ie, house dust mites, indoor molds, rodents, cockroaches, furry pets, and outdoor molds and pollens), and subsequent effects on asthma symptoms. We critically assess the available evidence regarding the clinical benefits of specific environmental control measures for each allergen. Finally, we underscore the need for standardized and multifaceted approaches in research and real-life settings, which would result in the identification of more personalized and beneficial prevention strategies.

Biological Response-Enhancing Activity with Antigens in A549 Cells Exposed to Representative Polycyclic Aromatic Hydrocarbons

The question of what kinds of airborne particles, including diesel exhaust particles and their adherent chemical constituents, exacerbate the activity of allergic and inflammatory respiratory diseases has not been elucidated in detail. Therefore, chemicals that have amplifying actions on Dermatophagoides farinae (Df) body extract-induced IL-8, the inflammatory cytokines of the innate immune system, were comprehensively examined using commonly used human alveolar epithelial cells, A549, as simple screening for 17 polycyclic aromatic hydrocarbons (PAHs), which are representative organic constituents in atmospheric samples. The significant amplifying actions of two PAHs, dibenzo[a,l]pyrene (DB[a,l]P) at 50 nM and dibenzo[a,i]pyrene (DB[a,i]P) at 2 μM for 48 h, for IL-8 protein release induced by mite antigens in epithelial cells were observed for the first time. In contrast, the enhancement of IL-8 was not observed in protein levels for these PAHs without the antigens. Meanwhile, the significant synergistic amplifying effect of DB[a,l]P at 50 nM on proinflammatory actions was measured in gene expression (i.e., IL-8, IL-6, ICAM-1, and TNF-α) levels in the experimental setting; for the results, the induction of TNF-α may have been the essential factor that enhanced the amplifying activity of DB[a,l]P for IL-8 gene expression and protein release. Examining the exacerbating effect on allergic pathophysiological states for DB[a,l]P is planned for further study.

Risk factors for recurrent respiratory tract infection in preschool-aged children

BACKGROUND

We aimed to identify potential risk factors for recurrent respiratory tract infection among Chinese preschool-aged children, and further to construct a nomogram prediction model.

METHODS

This is a cross-sectional survey conducted in Beijing. Utilizing a stratified cluster random sampling strategy, a total of 7222 children from 20 kindergartens were enrolled. Data are analyzed by STATA software and R language.

RESULTS

Five independent factors were identified to be significantly associated with recurrent respiratory tract infection risk overall and by pathogenic sites. The significant odds of recurrent respiratory tract infection was 8.31 (95% confidence interval [CI]: 5.69-12.12, P < 0.001), 2.31 (2.06-2.58, P < 0.001), 1.72 (1.48-1.99, P < 0.001), 1.24 (1.08-1.43, P = 0.002), and 1.19 (1.09-1.31, P < 0.001) for asthma, allergy, initial use of antibiotics <6 months, breastfeeding duration <6 months, and maternal body mass index, respectively. Besides the leading role played by asthma, allergy, initial use of antibiotics, and breastfeeding might exert a graded, dose-dependent effect on recurrent respiratory tract infection susceptibility.

CONCLUSIONS

We have identified five potential risk factors for the risk of recurrent respiratory tract infection from 7222 preschool-aged Chinese children. Notably, asthma plays a leading role, and allergy, initial use of antibiotics, and breastfeeding might exert a graded, dose-dependent effect on recurrent respiratory tract infection susceptibility.

IMPACT

This is the first report of examining the joint contribution of multiple potential risk factors to recurrent respiratory tract infection among Chinese preschool-aged children. We have identified five potential risk factors for the risk of recurrent respiratory tract infection via analyzing survey data from 7222 preschool-aged Chinese children. Asthma plays a leading role, and allergy, initial use of antibiotics, and breastfeeding might exert a graded, dose-dependent effect on recurrent respiratory tract infection susceptibility.

Microarray Technology May Reveal the Contribution of Allergen Exposure and Rhinovirus Infections as Possible Triggers for Acute Wheezing Attacks in Preschool Children

Allergen exposure and rhinovirus (RV) infections are common triggers of acute wheezing exacerbations in early childhood. The identification of such trigger factors is difficult but may have therapeutic implications. Increases of IgE and IgG in sera, were shown against allergens and the N-terminal portion of the VP1 proteins of RV species, respectively, several weeks after allergen exposure or RV infection. Hence, increases in VP1-specific IgG and in allergen-specific IgE may serve as biomarkers for RV infections or allergen exposure. The MeDALL-allergen chip containing comprehensive panels of allergens and the PreDicta RV chip equipped with VP1-derived peptides, representative of three genetic RV species, were used to measure allergen-specific IgE levels and RV-species-specific IgG levels in sera obtained from 120 preschool children at the time of an acute wheezing attack and convalescence. Nearly 20% of the children (22/120) showed specific IgE sensitizations to at least one of the allergen molecules on the MeDALL chip. For 87% of the children, increases in RV-specific IgG could be detected in the follow-up sera. This percentage of RV-specific IgG increases was equal in IgE-positive and -negative children. In 10% of the children, increases or de novo appearances of IgE sensitizations indicative of allergen exposure could be detected. Our results suggest that, in the majority of preschool children, RV infections trigger wheezing attacks, but, in addition, allergen exposure seems to play a role as a trigger factor. RV-induced wheezing attacks occur in IgE-sensitized and non-IgE-sensitized children, indicating that allergic sensitization is not a prerequisite for RV-induced wheeze.

Ascorbic Acid Suppresses House Dust Mite-Induced Expression of Interleukin-8 in Human Respiratory Epithelial Cells

House dust mite (HDM) is one of the significant causes for airway inflammation such as asthma. It induces oxidative stress and an inflammatory response in the lungs through the release of chemokines such as interleukin-8 (IL-8). Reactive oxygen species (ROS) activate inflammatory signaling mediators such as mitogen-activated protein kinases (MAPKs) and redox-sensitive transcription factors including NF-κB and AP-1. Ascorbic acid shows an antioxidant and anti-inflammatory activities in various cells. It ameliorated the symptoms of HDM-induced rhinitis. The present study was aimed to investigate whether HDM could induce IL-8 expression through activation of MAPKs, NF-κB, and AP-1 and whether ascorbic acid could inhibit HDM-stimulated IL-8 expression by reducing ROS and suppressing activation of MAPKs, NF-κB, and AP-1 in respiratory epithelial H292 cells. H292 cells were treated with HDM (5 μg/mL) in the absence or presence of ascorbic acid (100 or 200 μM). HDM treatment increased ROS levels, and activated MAPKs, NF-κB, and AP-1 and thus, induced IL-8 expression in H292 cells. Ascorbic acid reduced ROS levels and inhibited activation of MAPKs, NF-κB and AP-1 and L-8 expression in H292 cells. In conclusion, consumption of ascorbic acid-rich foods may be beneficial for prevention of HDM-mediated respiratory inflammation by suppressing oxidative stress-mediated MAPK signaling pathways and activation of NF-kB and AP-1.

House Dust Mite Exposure Causes Increased Susceptibility of Nasal Epithelial Cells to Adenovirus Infection

Adenovirus (AdV) infections in the respiratory tract may cause asthma exacerbation and allergic predisposition, and the house dust mite (HDM) may aggravate virus-induced asthma exacerbations. However, the underlying mechanisms of whether and how AdV affects asthmatic patients remains unclear. To address this question, we investigated nasal epithelial cells (NAEPCs) derived from a pediatric exacerbation study cohort for experimental analyses. We analyzed twenty-one different green-fluorescent protein- and luciferase-tagged AdV types in submerged 2D and organotypic 3D cell culture models. Transduction experiments revealed robust transduction of AdV type 5 (AdV5) in NAEPCs, which was associated with an increased uptake of AdV5 in the presence of HDM. In healthy and asthmatic NAEPCs exposed to HDM before infection, we observed a time- and dose-dependent increase of AdV5 uptake associated with upregulation of entry receptors for AdV5. Furthermore, electron microscopic and histologic analyses of 3D cell cultures revealed an impairment of the respiratory cilia after HDM exposition. This ex vivo pilot study shows the impact of AdV infection and HDM exposition in a primary cell culture model for asthma.

Toward personalization of asthma treatment according to trigger factors

Asthma is a severe and chronic disabling disease affecting more than 300 million people worldwide. Although in the past few drugs for the treatment of asthma were available, new treatment options are currently emerging, which appear to be highly effective in certain subgroups of patients. Accordingly, there is a need for biomarkers that allow selection of patients for refined and personalized treatment strategies. Recently, serological chip tests based on microarrayed allergen molecules and peptides derived from the most common rhinovirus strains have been developed, which may discriminate 2 of the most common forms of asthma, that is, allergen- and virus-triggered asthma. In this perspective, we argue that classification of patients with asthma according to these common trigger factors may open new possibilities for personalized management of asthma.

Development and characterization of DNAzyme candidates demonstrating significant efficiency against human rhinoviruses

BACKGROUND

Infections with human rhinoviruses (RVs) are responsible for millions of common cold episodes and the majority of asthma exacerbations, especially in childhood. No drugs specifically targeting RVs are available.

OBJECTIVE

We sought to identify specific anti-RV molecules based on DNAzyme technology as candidates to a clinical study.

METHODS

A total of 226 candidate DNAzymes were designed against 2 regions of RV RNA genome identified to be sufficiently highly conserved between virus strains (ie, the 5'-untranslated region and cis-acting replication element) by using 3 test strains: RVA1, RVA16, and RVA29. All DNAzymes were screened for their cleavage efficiency against in vitro-expressed viral RNA. Those showing any catalytic activity were subjected to bioinformatic analysis of their reverse complementarity to 322 published RV genomic sequences. Further molecular optimization was conducted for the most promising candidates. Cytotoxic and off-target effects were excluded in HEK293 cell-based systems. Antiviral efficiency was analyzed in infected human bronchial BEAS-2B cells and ex vivo-cultured human sinonasal tissue.

RESULTS

Screening phase-generated DNAzymes characterized by either good catalytic activity or by high RV strain coverage but no single molecule represented a satisfactory combination of those 2 features. Modifications in length of the binding domains of 2 lead candidates, Dua-01(-L12R9) and Dua-02(-L10R11), improved their cleavage efficiency to an excellent level, with no loss in eminent strain coverage (about 98%). Both DNAzymes showed highly favorable cytotoxic/off-target profiles. Subsequent testing of Dua-01-L12R9 in BEAS-2B cells and sinonasal tissue demonstrated its significant antiviral efficiency.

CONCLUSIONS

Effective and specific management of RV infections with Dua-01-L12R9 might be useful in preventing asthma exacerbations, which should be verified by clinical trials.

WNT/β-catenin pathway modulates the TNF-α-induced inflammatory response in bronchial epithelial cells

In this study, TNF-α was found to activate the WNT/β-catenin pathway in BEAS-2B human bronchial epithelial cells. Levels of phospho-LRP6, Dvl-2, and phospho-GSK-3β were elevated, while that of Axin was reduced by TNF-α treatment. Nuclear translocation of β-catenin and the reporter activity of a β-catenin-responsive promoter were increased by TNF-α treatment. Under the same experimental conditions, TNF-α activated the NF-κB signaling, which includes the phosphorylation and degradation of IκB and nuclear translocation and target DNA binding of NF-κB, and it was found that an inhibitor of NF-κB activation, JSH-23, inhibited TNF-α-induced Wnt signaling as well as NF-κB signaling. It was also found that recombinant Wnt proteins induced NF-κB nuclear translocations and its target DNA binding, suggesting that Wnt signaling and NF-κB signaling were inter-connected. TNF-α-induced modulations of IκB and NF-κB as well as pro-inflammatory cytokine expression were significantly suppressed by the transfection of β-catenin siRNA compared to that of control siRNA. Transfection of a β-catenin expression plasmid augmented the TNF-α-induced modulations of IκB and NF-κB as well as pro-inflammatory cytokine expression. These results clearly demonstrated that the WNT/β-catenin pathway modulates the inflammatory response induced by TNF-α, suggesting that this pathway may be a useful target for the effective treatment of bronchial inflammation.

LPS-induced inflammatory response is suppressed by Wnt inhibitors, Dickkopf-1 and LGK974

In this study, LPS-induced inflammatory responses in BEAS-2B human bronchial epithelial cells and human umbilical vein endothelial cell (HUVEC)s were found to be prevented by Dickkopf-1 (DKK-1), a secreted Wnt antagonist, and LGK974, a small molecular inhibitor of the Wnt secretion. LPS-induced IκB degradation and NF-κB nuclear translocation as well as the expressions of pro-inflammatory genes including IL-6, IL-8, TNF- α, IL-1β, MCP-1, MMP-9, COX-2 and iNOS, were all suppressed by DKK-1 and LGK974 in a dose-dependent manner. The suppressive effects of LGK974 on NF-κB, IκB, and pro-inflammatory gene expression were rescued by ectopic expression of β-catenin, suggesting that the anti-inflammatory activity of LGK974 is mediated by modulation of the Wnt/β-catenin pathway and not by unrelated side effects. When Wnt recombinant proteins were treated to cells, Wnt3a and Wnt5a significantly induced pro-inflammatory gene expressions, while Wnt7a and Wnt10b showed little effects. It was also found that Wnt3a and Wnt5a expressions were significantly induced by LPS treatment. Consistently, knockdown of Wnt3a and Wnt5a blocked LPS-induced inflammatory responses, while treatment of recombinant Wnt3a and Wnt5a proteins rescued the inhibition of inflammatory responses by LGK974. Findings of this study showed that DKK-1 and LGK974 suppress LPS-induced inflammatory response by modulating Wnt/β-catenin pathway.

Airway Epithelial Orchestration of Innate Immune Function in Response to Virus Infection. A Focus on Asthma

Asthma is a very common respiratory condition with a worldwide prevalence predicted to increase. There are significant differences in airway epithelial responses in asthma that are of particular interest during exacerbations. Preventing exacerbations is a primary aim when treating asthma because they often necessitate unscheduled healthcare visits and hospitalizations and are a significant cause of morbidity and mortality. The most common cause of asthma exacerbations is a respiratory virus infection, of which the most likely type is rhinovirus infection. This article focuses on the role played by the epithelium in orchestrating the innate immune responses to respiratory virus infection. Recent studies show impaired bronchial epithelial cell innate antiviral immune responses, as well as augmentation of a pro-Th2 response characterized by the epithelial-derived cytokines IL-25 and IL-33, crucial in maintaining the Th2 cytokine response to virus infection in asthma. 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 highlight current knowledge regarding the role of viruses and immune modulation in the asthmatic epithelium and to discuss exciting areas for future research and novel treatments.

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.

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.

Dexamethasone decreases IL-29 expression in house dust mite-stimulated human bronchial epithelial cells

The aim of this study was to explore the effect of IL-29 on the progression of airway allergic disease by detecting the level of IL-29 in airway allergic cell models stimulated by house dust mite (HDM) in the presence or absence of dexamethasone (DEX). The same batch of human bronchial epithelial cells in exponential growth phase was randomly divided into five groups: blank group (A), 300 ng/mL HDM group (B), 1000 ng/mL HDM group (C), 3000 ng/mL HDM group (D), and 300 ng/mL HDM+100 ng/mL DEX group (E). The IL-29 mRNA expression was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The IL-29 protein expression in cell suspension was detected by ELISA. The results showed that after stimulation with HDM for 24 h, the expression of IL-29 was increased significantly, and after co-stimulation with HDM and DEX for 24 h, the expression of IL-29 in group E was significantly lower than that in the groups stimulated by HDM alone but higher than that in the group A. The differences between the different groups were significant (F=132.957, P<0.01). Additionally, the higher the concentration of HDM was, the more significant the increase in the IL-29 expression was. In conclusion, IL-29 may play a role in the progression of airway allergic disease including asthma.

Effect of Ambroxol and Beclomethasone on Lipopolysaccharide-Induced Nitrosative Stress in Bronchial Epithelial Cells

BACKGROUND

Nitrosative stress is involved in different airway diseases. Lipopolysaccharide (LPS) induces neutrophil-related cytokine release and nitrosative stress in human bronchial epithelial (BEAS-2B) cells alone or with human polymorphonuclear neutrophils (PMNs). Ambroxol protects against oxidative stress, and beclomethasone dipropionate is an anti-inflammatory drug.

OBJECTIVES

We evaluated the ability of ambroxol and/or beclomethasone dipropionate to inhibit LPS-induced expression/release of RANTES, IL-8, inducible NO synthase (iNOS), myeloperoxidase (MPO) and 3-nitrotyrosine (3-NT: nitrosative stress biomarker) in BEAS-2B ± PMNs stimulated with LPS (1 μg/ml).

METHODS

The effect of ambroxol and/or beclomethasone dipropionate on IL-8, RANTES and iNOS levels was assessed by Western blot analysis; IL-8, MPO and 3-NT levels were measured by ELISA. Cell viability was assessed by the trypan blue exclusion test.

RESULTS

In BEAS-2B alone, LPS (at 12 h) increased RANTES/iNOS expression and IL-8 levels (p < 0.001). Ambroxol suppressed LPS-induced RANTES expression and IL-8 release (p < 0.001), whilst inhibiting iNOS expression (p < 0.05). Beclomethasone dipropionate had no effect on RANTES but halved iNOS expression and IL-8 release. Coculture of BEAS-2B with PMNs stimulated IL-8, MPO and 3-NT production (p < 0.001), potentiated by LPS (p < 0.001). Ambroxol and beclomethasone dipropionate inhibited LPS-stimulated IL-8, MPO and 3-NT release (p < 0.05). Ambroxol/beclomethasone dipropionate combination potentiated the inhibition of IL-8 and 3-NT production in BEAS-2B with PMNs (p < 0.05 and p < 0.01, respectively). Ambroxol and/or beclomethasone dipropionate inhibited nitrosative stress and the release of neutrophilic inflammatory products in vitro.

CONCLUSION

The additive effect of ambroxol and beclomethasone dipropionate on IL-8 and 3-NT inhibition suggests new therapeutic options in the treatment of neutrophil-related respiratory diseases such as chronic obstructive pulmonary disease and respiratory infections.

Contributing factors to the development of childhood asthma: working toward risk minimization

Asthma is the most common chronic disease in childhood, and considerable research has been undertaken to find ways to prevent its development and reduce its prevalence. For such interventions to be successful, risk factors for asthma emergence should be identified and clearly defined. Data are robust for some of them, including atopy, viral infections and exposure to airborne irritants, whereas it is less conclusive for others, such as aeroallergen exposure and bacterial infections. Several interventions for asthma prevention, including avoidance and pharmacotherapy, have been attempted. However, most of them have furnished equivocal results. Various issues hinder the establishment of risk factors for asthma development and reduce the effectiveness of interventions, including the complexity of the disease and the fluidity of the developing systems in childhood. In this review, we revisit the evidence on pediatric asthma risk factors and prevention and discuss issues that perplex this field.

Β-catenin regulates NF-κB activity and inflammatory cytokine expression in bronchial epithelial cells treated with lipopolysaccharide

In the present study, we demonstrate that lipopolysaccharide (LPS) induces the expression of inflammatory cytokines, including interleukin (IL)-6, IL-8, IL-1β, tumor necrosis factor (TNF)-α and monocyte chemoattractant protein (MCP)-1 in BEAS-2B human bronchial epithelial cells in a dose- and time-dependent manner. This increase was accompanied by an increased activity of nuclear factor (NF)‑κB. When the expression of β-catenin was analyzed following treatment with LPS, the mRNA level was unaltered; however, the β-catenin protein levels increased with a decrease in phosphorylation at the serine 33/37 residues. Nuclear β-catenin protein levels also increased along with the reporter activity of a β-catenin-responsive TOPFlash vector. To elucidate the regulatory role of β-catenin in the LPS-induced inflammatory response of bronchial epithelial cells, β-catenin production was knocked down using siRNA. Our results revealed that β-catenin protein levels and TOPFlash vector reporter activity were reduced to basal levels by siRNA transfection. In this experimental condition, NF-κB activity, measured by enzyme-linked immunosorbent assay (ELISA), electrophoretic mobility shift assay (EMSA) and an NF-κB responsive reporter assay, was reduced to basal levels. Similarly, LPS-induced inflammatory cytokine expression was reduced almost to basal levels following transfection with β-catenin siRNA. These results demonstrate that β-catenin positively regulates NF-κB activity, as well as the expression of inflammatory cytokines in the inflammatory response of LPS-treated bronchial epithelial cells.

PROPHYLACTIC ANTIBODY TREATMENT AND INTRAMUSCULAR IMMUNIZATION REDUCE INFECTIOUS HUMAN RHINOVIRUS 16 LOAD IN THE LOWER RESPIRATORY TRACT OF CHALLENGED COTTON RATS

Human rhinoviruses (HRV) represent the single most important etiological agents of the common cold and are the most frequent cause of acute respiratory infections in humans. Currently the performance of available animal models for immunization studies using HRV challenge is very limited. The cotton rat (Sigmodon hispidus) is a well-recognized model for the study of human respiratory viral infections. In this work we show that, without requiring any genetic modification of either the host or the virus, intranasal infection of cotton rats with HRV16 resulted in measurable isolation of infective virus, lower respiratory tract pathology, mucus production, and expression of interferon-activated genes. Intramuscular immunization with live HRV16 generated robust protective immunity that correlated with high serum levels of neutralizing antibodies. In addition, cotton rats treated prophylactically with hyperimmune anti-HRV16 serum were protected against HRV16 intranasal challenge. Finally, protection by immunization was efficiently transferred from mothers to newborn animals resulting in a substantial reduction of infectious virus loads in the lung following intranasal challenge. Overall, our results demonstrate that the cotton rat provides valuable additional model development options for testing vaccines and prophylactic therapies against rhinovirus infection.

β-catenin mediates the inflammatory cytokine expression induced by the Der p 1 house dust mite allergen

The modulations of β-catenin were analyzed during the inflammatory response induced by the Der p 1 house dust mite allergen. Der p 1 induced the dose-dependent expression of inflammatory cytokines, including interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) in THP-1 human monocytic cells. The mRNA expression levels of β-catenin were not altered, however protein levels increased following Der p 1 treatment, demonstrating that β-catenin was modulated by post-transcriptional processes. It was also revealed that nuclear β-catenin levels were significantly increased while cytoplasmic β-catenin levels were reduced, which demonstrated the nuclear translocation of β-catenin by the Der p 1 allergen. Glycogen synthase kinase 3β (GSK3β), a regulator of β-catenin stability, was demonstrated to be phosphorylated following Der p 1 treatment. When β-catenin was knocked down by the transfection of its small interfering RNA (siRNA), inflammatory cytokine expression as well as nuclear factor-κB (NF-κB) activity, which were induced by Der p 1 treatment, were all significantly reduced. The results demonstrated that Der p 1-induced inflammatory responses were mediated by β-catenin.

Rhinovirus infection causes steroid resistance in airway epithelium through nuclear factor κB and c-Jun N-terminal kinase activation

BACKGROUND

Although inhaled glucocorticoids are the mainstays of asthma treatment, they are poorly effective at treating and preventing virus-induced asthma exacerbations. The major viruses precipitating asthma exacerbations are rhinoviruses.

OBJECTIVE

We sought to evaluate whether rhinovirus infection interferes with the mechanisms of action of glucocorticoids.

METHODS

Cultured primary human bronchial or transformed (A549) respiratory epithelial cells were infected with rhinovirus 16 (RV-16) before dexamethasone exposure. Glucocorticoid receptor (GR) α nuclear translocation, glucocorticoid response element (GRE) binding, and transactivation/transrepression functional readouts were evaluated by using immunocytochemistry, Western blotting, DNA binding assays, real-time quantitative PCR, coimmunoprecipitation, and ELISA techniques. Specific inhibitors of c-Jun N-terminal kinase (JNK) and of IκB kinase (IKK) were used to investigate the involvement of intracellular signaling pathways.

RESULTS

RV-16 infection impaired dexamethasone-dependent (1) inhibition of IL-1β-induced CXCL8 release, (2) induction of mitogen-activated protein kinase phosphatase 1 gene expression, and (3) binding of GR to GREs in airway epithelial cells. This was associated with impaired GRα nuclear translocation, as assessed by means of both immunochemistry (54.0% ± 6.8% vs 24.7% ± 3.8% GR-positive nuclei after 10 nmol/L dexamethasone treatment in sham- or RV-16-infected cells, respectively; P < .01) and Western blotting. RV-16 infection induced nuclear factor κB activation and GRα phosphorylation, which were prevented by inhibitors of IKK2 and JNK, respectively. In rhinovirus-infected cells the combination of JNK and IKK2 inhibitors totally restored dexamethasone suppression of CXCL8 release, induction of mitogen-activated protein kinase phosphatase 1 gene expression, and GRα nuclear translocation.

CONCLUSION

RV-16 infection of human airway epithelium induces glucocorticoid resistance. Inhibition of RV-16-induced JNK and nuclear factor κB activation fully reversed rhinovirus impairment of both GRα nuclear translocation and the transactivation/transrepression activities of glucocorticoids.

Rhinovirus-Infected Epithelial Cells Produce More IL-8 and RANTES Compared With Other Respiratory Viruses

Purpose

The environmental factors human rhinoviruses (HRVs) and house dust mites (HDMs) are the most common causes of acute exacerbations of asthma. The aim of this study was to compare the chemokine production induced by HRVs in airway epithelial cells with that induced by other respiratory viruses, and to investigate synergistic interactions between HRVs and HDMs on the induction of inflammatory chemokines in vitro.

Methods

A549 human airway epithelial cells were infected with either rhinovirus serotype 7, respiratory syncytial virus (RSV)-A2 strain, or adenovirus serotype 3 and analyzed for interleukin (IL)-8 and regulated on activation, normal T-cell expressed and secreted (RANTES) release and mRNA expression. Additionally, activation of nuclear factor (NF)-κB and activator protein (AP)-1 were evaluated. The release of IL-8 and RANTES was also measured in cells stimulated simultaneously with a virus and the HDM allergen, Der f1.

Results

HRV caused greater IL-8 and RANTES release and mRNA expression compared with either RSV or adenovirus. NF-κB and AP-1 were activated in these processes. Cells incubated with a virus and Der f1 showed an increased IL-8 release. However, compared with cells incubated with virus alone as the stimulator, only HRV with Der f1 showed a statistically significant increase.

Conclusions

IL-8 and RANTES were induced to a greater extent by HRV compared with other viruses, and only HRV with Der f1 acted synergistically to induce bronchial epithelial IL-8 release. These findings may correspond with the fact that rhinoviruses are identified more frequently than other viruses in cases of acute exacerbation of asthma.

Acute asthma exacerbations in childhood: risk factors, prevention and treatment

Asthma is a heterogeneous disease more appropriately seen as a syndrome rather than a single pathologic entity. Although it can remain quiescent for extended time periods, the inflammatory and remodeling processes affect the bronchial milieu and predispose to acute and occasionally severe clinical manifestations. The complexity underlying these episodes is enhanced during childhood, an era of ongoing alterations and maturation of key biological systems. In this review, the authors focus on such sudden-onset events, emphasizing on their diversity on the basis of the numerous asthma phenotypes.

Recurrent lower respiratory tract infections in children: a practical approach to diagnosis

Many children are affected by recurrent lower respiratory tract infections (LRTIs), but the majority of them do not suffer from serious lung or extrapulmonary disease. The challenge for clinicians is to distinguish the recurrent RTIs with self-limiting or minor problems from those with underlying disease. The aim of this review is to describe a practical approach to children with recurrent LRTIs that limits unnecessary, expensive and time-consuming investigations. The children can be divided into three groups on the basis of their personal and family history and clinical findings: 1) otherwise healthy children who do not need further investigations; 2) those with risk factors for respiratory infections for whom a wait-and-see approach can be recommended; and 3) those in whom further investigations are mandatory. However, regardless of the origin of the recurrent LRTIs, it is important to remember that prevention by means of vaccines against respiratory pathogens (i.e. type b Haemophilus influenzae, pertussis, pneumococcal and influenza vaccines) can play a key role.

Defining critical roles for NF-κB p65 and type I interferon in innate immunity to rhinovirus

The importance of NF-κB activation and deficient anti-viral interferon induction in the pathogenesis of rhinovirus-induced asthma exacerbations is poorly understood. We provide the first in vivo evidence in man and mouse that rhinovirus infection enhanced bronchial epithelial cell NF-κB p65 nuclear expression, NF-κB p65 DNA binding in lung tissue and NF-κB-regulated airway inflammation. In vitro inhibition of NF-κB reduced rhinovirus-induced pro-inflammatory cytokines but did not affect type I/III interferon induction. Rhinovirus-infected p65-deficient mice exhibited reduced neutrophilic inflammation, yet interferon induction, antiviral responses and virus loads were unaffected, indicating that NF-κB p65 is required for pro-inflammatory responses, but redundant in interferon induction by rhinoviruses in vivo. Conversely, IFNAR1^−/− mice exhibited enhanced neutrophilic inflammation with impaired antiviral immunity and increased rhinovirus replication, demonstrating that interferon signalling was critical to antiviral immunity. We thus provide new mechanistic insights into rhinovirus infection and demonstrate the therapeutic potential of targeting NF-κB p65 (to suppress inflammation but preserve anti-viral immunity) and type I IFN signalling (to enhance deficient anti-viral immunity) to treat rhinovirus-induced exacerbations of airway diseases.

Predicting asthma exacerbations in children

PURPOSE OF REVIEW

This review critically assesses recently published literature on predicting asthma exacerbations in children, while also providing general recommendations for future research in this field.

RECENT FINDINGS

Current evidence suggests that every effort should be made to provide optimal treatment to achieve adequate asthma control, as this will significantly reduce the risk of severe disease exacerbations. Children who have had at least one asthma exacerbation in the previous year are at highest risk for subsequent exacerbations, regardless of disease severity and/or control. Although several tools and biomarkers to predict asthma exacerbations have been recently developed, these approaches need further validation and/or have only had partial success in identifying children at risk.

SUMMARY

Although considerable progress has been made, much remains to be done. Future studies should clearly differentiate severe asthma exacerbations due to inadequate asthma control from those occurring in children whose asthma is well controlled, utilize standardized definitions of asthma exacerbations, and use a systematic approach to identify the best predictors after accounting for the multiple dimensions of the problem. Our ability to correctly predict the development of severe asthma exacerbations in an individual child should improve in parallel with increased knowledge and/or understanding of the complex interactions among genetic, environmental (e.g. viral infections) and lifestyle (e.g. adherence to treatment) factors underlying these events.

CD14+ cell-derived IL-29 modulates proinflammatory cytokine production in patients with allergic airway inflammation

BACKGROUND

  Interleukin (IL)-29 is a newly described cytokine that has anti-viral activity, induces tumor cell death and regulates immune function. Whether it plays a role in immune disorders is unclear. This study aims to examine the role of IL-29 in the modulation of immune response under allergic environment.

METHODS

  A group of patients with allergic asthma or/and allergic rhinitis was recruited to this study. Serum samples were collected from the patients in both in-season and out-season; the serum levels of IL-29 were determined by enzyme-linked immunoassay. Cell types of IL-29-producing cells in upper airway mucosa were identified with immune staining and examined by immunohistochemistry and flow cytometry.

RESULTS

  High serum levels of IL-29 were detected in patients with allergic asthma in in-season, but not in out-season. The majority of IL-29(+) cells in upper airway tissue were CD14(+) cells. Exposure to specific antigens triggered the release of IL-4 from antigen-specific CD4(+) T cells; the released IL-4 activated CD14(+) cells to release IL-29; the released IL-29 further triggered the release of IL-6 and tumor necrosis factor from CD4(+) T cells.

CONCLUSIONS

  Interleukin-29 is involved in the pathogenesis of allergic inflammation via modulating immune cells' function to release proinflammatory cytokines.

IL-28A, IL-28B, and IL-29: promising cytokines with type I interferon-like properties

IL-28A, IL-28B and IL-29 (also designated type III interferons) constitute a new subfamily within the IL-10-interferon family. They are produced by virtually any nucleated cell type, particularly dendritic cells, following viral infection or activation with bacterial components, and mediate their effects via the IL-28R1/IL-10R2 receptor complex. Although IL-28/IL-29 are closer to the IL-10-related cytokines in terms of gene structure, protein structure, and receptor usage, they display type I interferon-like anti-viral and cytostatic activities. Unlike type I interferons, the target cell populations of IL-28/IL-29 are restricted and mainly include epithelial cells and hepatocytes. These properties suggest that IL-28/IL-29 are potential therapeutic alternatives to type I interferons in terms of viral infections and tumors. This review describes the current knowledge about these cytokines.

Rhinovirus-infected nasal polyp epithelial cells: effect on the activation and migration of eosinophils by airborne fungi

BACKGROUND

Rhinovirus and fungi are common environmental factors able to induce airway inflammation. They are associated with the production of chemical mediators by direct activation of epithelial cells.

OBJECTIVE

To evaluate the effect of fungal stimulation of rhinovirus-infected nasal polyp epithelial cells (NPECs) on the activation and migration of eosinophils.

METHODS

Rhinovirus-infected NPECs were stimulated with Alternaria and Aspergillus for 48 hours. Then, epithelial cells were co-cultured with freshly isolated eosinophils. An eosinophil migration study was performed with epithelial cell-conditioned media. Interleukin 6, interleukin 8, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor levels were measured to determine the activation of cells.

RESULTS

Airborne fungi enhanced the production of cytokines from rhinovirus 16-infected NPECs compared with fungi stimulation or rhinovirus 16 infection alone. Rhinovirus 16-infected NPECs were co-cultured with eosinophils, and cytokine production was not significantly increased except tumor necrosis factor-alpha production by Aspergillus. Epithelial cell-conditioned media, which were stimulated with fungi, enhanced the migration of eosinophils.

CONCLUSIONS

There was some synergism between rhinovirus 16 infection and airborne fungal exposure, enhancing the inflammatory response of airway epithelial cells.

Developments in the field of allergy in 2008 through the eyes of Clinical & Experimental Allergy

In 2008, many thousands of articles were published on the subject of allergic disease with over 200 reviews, editorials and original papers in Clinical & Experimental Allergy alone. These represent a considerable amount of data and even the most avid reader could only hope to assimilate a small fraction of this knowledge. There is therefore a pressing need for the key messages that emerge from a journal such as Clinical & Experimental Allergy to be summarized by experts in the field in a form that highlights the significance of the developments and sets them in the context of important findings in the field published in other journals. This also has the advantage of making connections between new data in conditions such as asthma, where articles often appear in different sections of the journal. As can be seen from this review, the body of work is diverse both in terms of the disease of interest and the discipline that has been used to investigate it. However, taken as a whole, we hope that the reader will gain a flavour of where the field is mature, where there remain controversies and where the cutting edge is leading.

A new look at the pathogenesis of asthma

Asthma is an inflammatory disorder of the conducting airways that has strong association with allergic sensitization. The disease is characterized by a polarized Th-2 (T-helper-2)-type T-cell response, but in general targeting this component of the disease with selective therapies has been disappointing and most therapy still relies on bronchodilators and corticosteroids rather than treating underlying disease mechanisms. With the disappointing outcomes of targeting individual Th-2 cytokines or manipulating T-cells, the time has come to re-evaluate the direction of research in this disease. A case is made that asthma has its origins in the airways themselves involving defective structural and functional behaviour of the epithelium in relation to environmental insults. Specifically, a defect in barrier function and an impaired innate immune response to viral infection may provide the substrate upon which allergic sensitization takes place. Once sensitized, the repeated allergen exposure will lead to disease persistence. These mechanisms could also be used to explain airway wall remodelling and the susceptibility of the asthmatic lung to exacerbations provoked by respiratory viruses, air pollution episodes and exposure to biologically active allergens. Variable activation of this epithelial-mesenchymal trophic unit could also lead to the emergence of different asthma phenotypes and a more targeted approach to the treatment of these. It also raises the possibility of developing treatments that increase the lung's resistance to the inhaled environment rather than concentrating all efforts on trying to suppress inflammation once it has become established.

Novel concepts in virally induced asthma

Viruses are the predominant infectious cause of asthma exacerbations in the developed world. In addition, recent evidence strongly suggests that viral infections may also have a causal role in the development of childhood asthma. In this article, we will briefly describe the general perception of how the link between infections and asthma has changed over the last century, and then focus on very recent developments that have provided new insights into the contribution of viruses to asthma pathogenesis. Highlighted areas include the contribution of severe early life viral infections to asthma inception, genetic determinants of severe viral infections in infancy, the differences in innate and adaptive immune system cytokine responses to viral infection between asthmatic and nonasthmatic subjects, and a potential vaccine strategy to prevent severe early life virally-induced illness.