Asthma and natural colds. Inflammatory indices in induced sputum: a feasibility study

Analysis of Exosomal MicroRNA Dynamics in Response to Rhinovirus Challenge in a Longitudinal Case-Control Study of Asthma

Asthma symptoms are often exacerbated by the common-cold-causing rhinovirus (RV). In this study, we characterized the temporal behavior of circulating exosomal microRNAs (ExoMiRNAs) in a longitudinal bi-phasic case-control study of mild asthmatics (n = 12) and matched non-atopic healthy controls (n = 12) inoculated with rhinovirus. We aimed to define clinical and immunologic characteristics associated with differentially expressed (DE) miRNAs. In total, 26 DE ExoMiRNAs, including hsa-let-7f-5p, hsa-let-7a-5p, hsa-miR-122-5p, hsa-miR-101-3p, and hsa-miR-126-3p, were identified between asthmatic and healthy subjects after inoculation with RV. Time series clustering identified a unique Cluster of Upregulated DE ExoMiRNAs with augmenting mean expression and a distinct Cluster of Downregulated DE ExoMiRNAs with mean expression decline in asthmatic subjects upon RV challenge. Notably, the Upregulated Cluster correlated with Th1 and interferon-induced cytokines/chemokines (IFN-γ and IFN-γ-inducible protein-10) and interleukin-10 (IL-10). Conversely, the Downregulated Cluster correlated with IL-13, a Th2 cytokine, pulmonary function measurements (FVC%, FEV1%, and PEF%), and inflammatory biomarkers (FeNO, eosinophil%, and neutrophil%). Key ExoMiRNA-target gene and anti-viral defense mechanisms of the Upregulated and Downregulated Clusters were identified by network and gene enrichment analyses. Our findings provide insight into the regulatory role of ExoMiRNAs in RV-induced asthma.

Innate Immune Responses by Respiratory Viruses, Including Rhinovirus, During Asthma Exacerbation

Viral infection, especially with rhinovirus (RV), is a major cause of asthma exacerbation. The production of anti-viral cytokines such as interferon (IFN)-β and IFN-α from epithelial cells or dendritic cells is lower in patients with asthma or those with high IgE, which can contribute to viral-induced exacerbated disease in these patients. As for virus-related factors, RV species C (RV-C) induces more exacerbated disease than other RVs, including RV-B. Neutrophils activated by viral infection can induce eosinophilic airway inflammation through different mechanisms. Furthermore, virus-induced or virus-related proteins can directly activate eosinophils. For example, CXCL10, which is upregulated during viral infection, activates eosinophils in vitro. The role of innate immune responses, especially type-2 innate lymphoid cells (ILC2) and epithelial cell-related cytokines including IL-33, IL-25, and thymic stromal lymphopoietin (TSLP), in the development of viral-induced airway inflammation has recently been established. For example, RV infection induces the expression of IL-33 or IL-25, or increases the ratio of ILC2 in the asthmatic airway, which is correlated with the severity of exacerbation. A mouse model has further demonstrated that virus-induced mucous metaplasia and ILC2 expansion are suppressed by antagonizing or deleting IL-33, IL-25, or TSLP. For treatment, IFNs including IFN-β suppress not only viral replication but also ILC2 activation in vitro. Agonists of toll-like receptor (TLR) 3 or 7 can induce IFNs, which can then suppress viral replication and ILC2 activation. Therefore, if delivered in the airway, IFNs or TLR agonists could become innovative treatments for virus-induced asthma exacerbation.

2021 Brazilian Thoracic Association recommendations for the management of severe asthma

Advances in the understanding that severe asthma is a complex and heterogeneous disease and in the knowledge of the pathophysiology of asthma, with the identification of different phenotypes and endotypes, have allowed new approaches for the diagnosis and characterization of the disease and have resulted in relevant changes in pharmacological management. In this context, the definition of severe asthma has been established, being differentiated from difficult-to-control asthma. These recommendations address this topic and review advances in phenotyping, use of biomarkers, and new treatments for severe asthma. Emphasis is given to topics regarding personalized management of the patient and selection of biologicals, as well as the importance of evaluating the response to treatment. These recommendations apply to adults and children with severe asthma and are targeted at physicians involved in asthma treatment. A panel of 17 Brazilian pulmonologists was invited to review recent evidence on the diagnosis and management of severe asthma, adapting it to the Brazilian reality. Each of the experts was responsible for reviewing a topic or question relevant to the topic. In a second phase, four experts discussed and structured the texts produced, and, in the last phase, all experts reviewed and approved the present manuscript and its recommendations.

Stability of sputum inflammatory phenotypes in childhood asthma during stable and exacerbation phases

BACKGROUND

Management strategies based on airway inflammation phenotypes are increasingly used for adults with asthma. While sputum-based phenotypes are relatively stable in adults with asthma, there is little such data in childhood asthma. Hence, we aimed to evaluate the stability of sputum inflammatory phenotypes in children with asthma both in the stable and during exacerbation phases.

METHODS

Sputum cellularity data from two previous prospective studies involving children with asthma were re-evaluated and categorized into two inflammatory phenotypes: eosinophilic (>2.5% eosinophils) and noneosinophilic (≤2.5% eosinophils). Baseline values and follow-up sputum inflammatory phenotype classification were compared in children with asthma during stable and exacerbation phases.

RESULTS

Thirteen of 32 children (41%) with stable asthma demonstrated a change in sputum inflammatory phenotype 8 weeks later. In a different second cohort, both sputum eosinophils and neutrophils percentages increased and peaked on Day 1 of asthma exacerbation, but compared with baseline, 22% (2/9) and 13% (1/8) of these children had their sputum phenotype categorization changed on Day 1 and Day 3 of exacerbation, respectively.

CONCLUSION

In children with asthma, sputum inflammatory phenotypes are variable in both stable and exacerbation phases, in contrast to data in adults.

Impact of human rhinoviruses on gene expression in pediatric patients with severe acute respiratory infection

Human rhinovirus (HRV) is one of the most common viruses, causing mild to severe respiratory tract infections in children and adults. Moreover, it can lead to patients' hospitalization. Nowadays, evaluation of gene expression alterations in host cells due to viral respiratory infections considered essential to understand the viral effects on cells.

OBJECTIVE

In this study, we aimed to find important differentially expressed genes (DEGs) related to rhinitis and asthma exacerbation stimulated with Poly (I: C) and then to validate their expression in clinical samples of children how were less than 5 years old, hospitalized with severe acute respiratory infection (SARI) due to HRV infection in comparison with healthy cases.

METHODS

Eight candidate genes involved in immunity, viral defense, inflammation, P53 pathway, and viral release processes were selected based on the analysis of a gene expression data set (GSE51392) and gene enrichment analysis. Then quantitative real-time PCR on cDNAs was performed for selected genes. The results were analyzed by Livak method and visualized by GraphPad prism software (8.4.3).

RESULT

CXCL10, CMPK2, RSAD2, SERPINA3, TNFAIP6, CXCL14, IVNS1AB, and ZMAT3 were selected based on the enrichment and topological analysis of the constructed protein-protein interaction (PPI) network. Laboratory validation by real-time PCR showed CXCL10, CMPK2, RSAD2, SERPINA3, and TNFAIP6 (belonged to immunity, inflammatory responses and viral defense) were up-regulated, whereas CXCL14 (related to immunity) and IVNS1AB, ZMAT3 (associated to Influenza and P53 pathway) were down-regulated.

CONCLUSION

Our results showed, that in children less than 5 years old affected by HRV and hospitalized with SARI, the inflammatory responses, antiviral defense, and type 1 interferon-signaling pathway have significantly affected by viral infection.

Early humoral defence: Contributing to confining COVID-19 to conducting airways?

Early airway responses to severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) infection are of interest since they could decide whether coronavirus disease‐19 (COVID‐19) will proceed to life‐threatening pulmonary disease stages. Here I discuss endothelial‐epithelial co‐operative in vivo responses producing first‐line, humoral innate defence opportunities in human airways. The pseudostratified epithelium of human nasal and tracheobronchial airways are prime sites of exposure and infection by SARS‐CoV‐2. Just beneath the epithelium runs a profuse systemic microcirculation. Its post‐capillary venules respond conspicuously to mucosal challenges with autacoids, allergens and microbes, and to mere loss of epithelium. By active venular endothelial gap formation, followed by transient yielding of epithelial junctions, non‐sieved plasma macromolecules move from the microcirculation to the mucosal surface. Hence, plasma‐derived protein cascade systems and antimicrobial peptides would have opportunity to operate jointly on an unperturbed mucosal lining. Similarly, a plasma‐derived, dynamic gel protects sites of epithelial sloughing‐regeneration. Precision for this indiscriminate humoral molecular response lies in restricted location and well‐regulated duration of plasma exudation. Importantly, the endothelial responsiveness of the airway microcirculation differs distinctly from the relatively non‐responsive, low‐pressure pulmonary microcirculation that non‐specifically, almost irreversibly, leaks plasma in life‐threatening COVID‐19. Observations in humans of infections with rhinovirus, coronavirus 229E, and influenza A and B support a general but individually variable early occurrence of plasma exudation in human infected nasal and tracheobronchial airways. Investigations are warranted to elucidate roles of host‐ and drug‐induced airway plasma exudation in restriction of viral infection and, specifically, whether it contributes to variable disease responses following exposure to SARS‐CoV‐2.

Virus-Induced Asthma Exacerbations: SIRT1 Targeted Approach

The prevalence of asthma has increased worldwide. Asthma exacerbations triggered by upper respiratory tract viral infections remain a major clinical problem and account for hospital admissions and time lost from work. Virus-induced asthma exacerbations cause airway inflammation, resulting in worsening asthma and deterioration in the patients’ quality of life, which may require systemic corticosteroid therapy. Despite recent advances in understanding the cellular and molecular mechanisms underlying asthma exacerbations, current therapeutic modalities are inadequate for complete prevention and treatment of these episodes. The pathological role of cellular senescence, especially that involving the silent information regulator 2 homolog sirtuin (SIRT) protein family, has recently been demonstrated in stable and exacerbated chronic respiratory disease states. This review discusses the role of SIRT1 in the pathogenesis of bronchial asthma. It also discusses the role of SIRT1 in inflammatory cells that play an important role in virus-induced asthma exacerbations. Recent studies have hypothesized that SIRT1 is one of major contributors to cellular senescence. SIRT1 levels decrease in Th2 and non-Th2-related airway inflammation, indicating the role of SIRT1 in several endotypes and phenotypes of asthma. Moreover, several models have demonstrated relationships between viral infection and SIRT1. Therefore, targeting SIRT1 is a novel strategy that may be effective for treating virus-induced asthma exacerbations in the future.

Mechanisms of eosinophilic inflammation

Eosinophils play roles in the pathogenesis of various diseases. In order to accumulate within sites of inflammation, eosinophils must adhere to, and migrate across the microvasculature. These processes are largely controlled by type 2-immune responses; interleukin (IL)-4 and IL-13 induce the expression of endothelial adhesion molecule vascular cell adhesion molecule-1 (VCAM-1), a representative adhesive ligand for eosinophils, while also stimulating generations of CC chemokines from structural cells, including epithelial cells. VCAM-1 and CC chemokines synergistically induce transmigration of eosinophils to the tissue inflammation site. Another type 2 cytokine, IL-5, prolongs survival, and enhances the effector functions of eosinophils. Recently, accumulating evidence has established that corticosteroid-resistant group 2 innate lymphoid cells are cellular sources for IL-5. Another immunological mechanism that may be contributing to eosinophilic inflammation involves type 1 immune system-associated molecules such as interferons and IP-10. In addition to these immune pathways, lipid mediators, such as cysteinyl leukotrienes, directly provoke the infiltration and activation of eosinophils. Extracellular matrix proteins including periostin also induce the adhesion and activation of eosinophils. Finally, activated neutrophils can also induce eosinophil transmigration. In summary, various mechanisms are involved within eosinophilic inflammation, and effective therapeutic strategies targeting these pathways should be established.

Severe exacerbations in moderate-to-severe asthmatics are associated with increased pro-inflammatory and type 1 mediators in sputum and serum

BACKGROUND

Asthma is a heterogeneous disease and understanding this heterogeneity will enable the realisation of precision medicine. We sought to compare the sputum and serum inflammatory profiles in moderate-to-severe asthma during stable disease and exacerbation events.

METHODS

We recruited 102 adults and 34 children with asthma. The adults were assessed at baseline, 3, 6, and 12-month follow-up visits. Thirty-seven subjects were assessed at onset of severe exacerbation. Forty sputum mediators and 43 serum mediators were measured. Receiver-operator characteristic (ROC) curves were constructed to identify mediators that distinguish between stable disease and exacerbation events. The strongest discriminating sputum mediators in the adults were validated in the children.

RESULTS

The mediators that were significantly increased at exacerbations versus stable disease and by ≥1.5-fold were sputum IL-1β, IL-6, IL-6R, IL-18, CXCL9, CXCL10, CCL5, TNFα, TNF-R1, TNF-R2, and CHTR and serum CXCL11. No mediators decreased ≥1.5-fold at exacerbation. The strongest discriminators of an exacerbation in adults (ROC area under the curve [AUC]) were sputum TNF-R2 0.69 (95% CI: 0.60 to 0.78) and IL-6R 0.68 (95% CI: 0.58 to 0.78). Sputum TNF-R2 and IL-6R were also discriminatory in children (ROC AUC 0.85 [95% CI: 0.71 to 0.99] and 0.80 [0.64 to 0.96] respectively).

CONCLUSIONS

Severe asthma exacerbations are associated with increased pro-inflammatory and Type 1 (T1) immune mediators. In adults, sputum TNF-R2 and IL-6R were the strongest discriminators of an exacerbation, which were verified in children.

Exacerbations of chronic respiratory diseases

Respiratory viral infections including human rhinovirus (RV) infection have been identified as the most important environmental trigger of exacerbations of chronic lung diseases. While well established as the most common viral infections associated with exacerbations of asthma and chronic obstructive pulmonary disease, RVs and other respiratory viruses are also now thought to be important in triggering exacerbations of cystic fibrosis and the interstitial lung diseases. Here, we summarize the epidemiological evidence the supports respiratory viruses including RV as triggers of exacerbations of chronic lung diseases. We propose that certain characteristics of RVs may explain why they are the most common trigger of exacerbations of chronic lung diseases. We further highlight the latest mechanistic evidence supporting how and why common respiratory viral infections may enhance and promote disease triggering exacerbation events, through their interactions with the host immune system, and may be affected by ongoing treatments. We also provide a commentary on how new treatments may better manage the disease burden associated with respiratory viral infections and the exacerbation events that they trigger.

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.

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.

Involvement and Possible Role of Eosinophils in Asthma Exacerbation

Eosinophils are involved in the development of asthma exacerbation. Recent studies have suggested that sputum and blood eosinophil counts are important factors for predicting asthma exacerbation. In severe eosinophilic asthma, anti-interleukin (IL)-5 monoclonal antibody decreases blood eosinophil count and asthma exacerbation frequency. However, even in the absence of IL-5, eosinophilic airway inflammation can be sufficiently maintained by the T helper (Th) 2 network, which comprises a cascade of vascular cell adhesion molecule-1/CC chemokines/eosinophil growth factors, including granulocyte-macrophage colony-stimulating factor (GM-CSF). Periostin, an extracellular matrix protein and a biomarker of the Th2 immune response in asthma, directly activates eosinophils in vitro. A major cause of asthma exacerbation is viral infection, especially rhinovirus (RV) infection. The expression of intercellular adhesion molecule (ICAM)-1, a cellular receptor for the majority of RVs, on epithelial cells is increased after RV infection, and adhesion of eosinophils to ICAM-1 can upregulate the functions of eosinophils. The expressions of cysteinyl leukotrienes (cysLTs) and CXCL10 are upregulated in virus-induced asthma. CysLTs can directly provoke eosinophilic infiltration in vivo and activate eosinophils in vitro. Furthermore, eosinophils express the CXC chemokine receptor 3, and CXCL10 activates eosinophils in vitro. Both eosinophils and neutrophils contribute to the development of severe asthma or asthma exacerbation. IL-8, which is an important chemoattractant for neutrophils, is upregulated in some cases of severe asthma. Lipopolysaccharide (LPS), which induces IL-8 from epithelial cells, is also increased in the lower airways of corticosteroid-resistant asthma. IL-8 or LPS-stimulated neutrophils increase the transbasement membrane migration of eosinophils, even in the absence of chemoattractants for eosinophils. Therefore, eosinophils are likely to contribute to the development of asthma exacerbation through several mechanisms, including activation by Th2 cytokines, such as IL-5 or GM-CSF or by virus infection-related proteins, such as CXCL10, and interaction with other cells, such as neutrophils.

Airways exudation of plasma macromolecules: Innate defense, epithelial regeneration, and asthma

This review discusses in vivo airway aspects of plasma exudation in relation to current views on epithelial permeability and epithelial regeneration in health and disease. Microvascular-epithelial exudation of bulk plasma proteins characteristically occurs in asthmatic patients, being especially pronounced in those with severe and exacerbating asthma. Healthy human and guinea pig airways challenged by noninjurious histamine-leukotriene–type autacoids also respond through prompt mucosal exudation of nonsieved plasma macromolecules. Contrary to current beliefs, epithelial permeability in the opposite direction (ie, absorption of inhaled molecules) has not been increased in patients with asthma and allergic rhinitis or in acutely exuding healthy airways. A slightly increased subepithelial hydrostatic pressure produces such unidirectional outward perviousness to macromolecules. Lack of increased absorption permeability in asthmatic patients can further be reconciled with occurrence of epithelial shedding, leaving small patches of denuded basement membrane. Counteracting escalating barrier breaks, plasma exudation promptly covers the denuded patches. Here it creates and sustains a biologically active barrier involving a neutrophil-rich, fibrin-fibronectin net. Furthermore, in the plasma-derived milieu, all epithelial cell types bordering the denuded patch dedifferentiate and migrate from all sides to cover the denuded basement membrane. However, this speedy epithelial regeneration can come at a cost. Guinea pig in vivo studies demonstrate that patches of epithelial denudation regeneration are exudation hot spots evoking asthma-like features, including recruitment/activation of granulocytes, proliferation of fibrocytes/smooth muscle cells, and basement membrane thickening. In conclusion, nonsieved plasma macromolecules can operate on the intact airway mucosa as potent components of first-line innate immunity responses. Exuded plasma also takes center stage in epithelial regeneration. When exaggerated, epithelial regeneration can contribute to the inception and development of asthma.

Adrenergic Signaling at the Interface of Allergic Asthma and Viral Infections

Upper respiratory viral infections are a major etiologic instigator of allergic asthma, and they drive severe exacerbations of allergic inflammation in the lower airways of asthma sufferers. Rhinovirus (RV), in particular, is the main viral instigator of these pathologies. Asthma exacerbations due to RV infections are the most frequent reasons for hospitalization and account for the majority of morbidity and mortality in asthma patients. In both critical care and disease control, long- and short-acting β2-agonists are the first line of therapeutic intervention, which are used to restore airway function by promoting smooth muscle cell relaxation in bronchioles. While prophylactic use of β2-agonists reduces the frequency and pathology of exacerbations, their role in modulating the inflammatory response is only now being appreciated. Adrenergic signaling is a component of the sympathetic nervous system, and the natural ligands, epinephrine and norepinephrine (NE), regulate a multitude of autonomic functions including regulation of both the innate and adaptive immune response. NE is the primary neurotransmitter released by post-ganglionic sympathetic neurons that innervate most all peripheral tissues including lung and secondary lymphoid organs. Thus, the adrenergic signaling pathways are in direct contact with both the central and peripheral immune compartments. We present a perspective on how the adrenergic signaling pathway controls immune function and how β2-agonists may influence inflammation in the context of virus-induced asthma exacerbations.

The use of cellular and molecular biomarkers to manage COPD exacerbations

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) exacerbations are a common cause of respiratory morbidity and mortality, and have various etiologies. Multiple cellular and molecular biomarkers have been associated with exacerbations. Quantitative sputum cell counts are able to identify the presence and type of bronchitis, which is an important contributor to exacerbations. Their utility to monitor bronchitis and to help treat exacerbations has been evaluated, yet they are not used in routine clinical practice. Areas covered: This review will provide a brief summary of biomarkers utilized in COPD, with a focus on the application of cellular markers for the management of exacerbations. A case study will demonstrate the application of these methods. With quantitative sputum cell counts, the presence of eosinophilic bronchitis predicts corticosteroid-responsiveness, while neutrophilic bronchitis identifies infection and suggests the need for antibiotics. Gastroesophageal reflux-related aspiration and heart failure can also be identified by examining sputum. Expert commentary: Quantitative sputum cytometry is an essential tool in the management of exacerbations of COPD, particularly those prone to frequent exacerbations. Treatment based on sputum cell counts is superior to current guideline-based recommendations to prevent future exacerbations and hospitalizations in observational and single-centre controlled trials. Large multicentre clinical trials are necessary to confirm this.

Clinical characteristics of asthmatic patients with influenza-like illness and risk of severe exacerbations in Mexico

BACKGROUND

Patients with chronic inflammatory lung diseases, such as asthma, are at higher risk for influenza-like illness (ILI) complications. Viral infections are known to trigger asthma exacerbations, but a thorough description of the clinical characteristics of ILI-associated asthma exacerbations and the role of viruses as a risk factor for severe exacerbation (SE) in ILI has not been published yet.

OBJECTIVE

To investigate risk factors for SE in patients with ILI and asthma.

METHODS

Patients with ILI symptoms were recruited from 6 hospitals of Mexico (LaRed sites) during 2010 to 2014. Those with a previous asthma diagnosis and ILI symptoms and who were 5 years or older were included. Patients were assigned as cases or controls based on symptoms reported. SE was defined when participants presented with wheezing or dyspnea and required hospitalization.

RESULTS

A total of 486 patients with ILI and a diagnosis of asthma were included. There were no differences in the proportion, number, or type of viral illness among those with and without SE. Those with SE were less likely to report ILI symptoms. Muscle pain and nasal drip were predictors for patients not progressing to SE. A delay in seeking medical care was associated with SE (odds ratio, 2.93; 95% CI, 1.46-5.88).

CONCLUSION

The presence of a particular virus did not predict SE. ILI symptoms in asthma patients are not associated with severe exacerbation. Patients with asthma should be encouraged to seek early medical care when ILI symptoms are first noticed to prevent serious complications.

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.

Extended B cell phenotype in patients with myalgic encephalomyelitis/chronic fatigue syndrome: a cross-sectional study

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a heterogeneous condition of unknown aetiology characterized by multiple symptoms including fatigue, post-exertional malaise and cognitive impairment, lasting for at least 6 months. Recently, two clinical trials of B cell depletion therapy with rituximab (anti-CD20) reported convincing improvement in symptoms. A possible but undefined role for B cells has therefore been proposed. Studies of the relative percentages of B cell subsets in patients with ME/CFS have not revealed any reproducible differences from healthy controls (HC). In order to explore whether more subtle alterations in B cell subsets related to B cell differentiation exist in ME/CFS patients we used flow cytometry to immunophenotype CD19⁺ B cells. The panel utilized immunoglobulin (Ig)D, CD27 and CD38 (classical B cell subsets) together with additional markers. A total of 38 patients fulfilling Canadian, Centre for Disease Control and Fukuda ME/CFS criteria and 32 age- and sex-matched HC were included. We found no difference in percentages of classical subsets between ME/CFS patients and HC. However, we observed an increase in frequency (P < 0·01) and expression (MFI; P = 0·03) of CD24 on total B cells, confined to IgD⁺ subsets. Within memory subsets, a higher frequency of CD21⁺ CD38⁻ B cells (> 20%) was associated with the presence of ME/CFS [odds ratio: 3·47 (1·15-10·46); P = 0·03] compared with HC, and there was a negative correlation with disease duration. In conclusion, we identified possible changes in B cell phenotype in patients with ME/CFS. These may reflect altered B cell function and, if confirmed in other patient cohorts, could provide a platform for studies based on clinical course or responsiveness to rituximab therapy.

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.

CXC chemokines and antimicrobial peptides in rhinovirus-induced experimental asthma exacerbations

RATIONALE

Rhinoviruses (RVs) are the major triggers of asthma exacerbations. We have shown previously that lower respiratory tract symptoms, airflow obstruction, and neutrophilic airway inflammation were increased in experimental RV-induced asthma exacerbations.

OBJECTIVES

We hypothesized that neutrophil-related CXC chemokines and antimicrobial peptides are increased and related to clinical, virologic, and pathologic outcomes in RV-induced exacerbations of asthma.

METHODS

Protein levels of antimicrobial peptides (SLPI, HNP 1-3, elafin, and LL-37) and neutrophil chemokines (CXCL1/GRO-α, CXCL2/GRO-β, CXCL5/ENA-78, CXCL6/GCP-2, CXCL7/NAP-2, and CXCL8/IL-8) were determined in bronchoalveolar lavage (BAL) fluid of 10 asthmatics and 15 normal controls taken before, at day four during and 6 weeks post-experimental infection.

RESULTS

BAL HNP 1-3 and Elafin were higher, CXCL7/NAP-2 was lower in asthmatics compared with controls at day 4 (P = 0.035, P = 0.048, and P = 0.025, respectively). BAL HNP 1-3 and CXCL8/IL-8 were increased during infection (P = 0.003 and P = 0.011, respectively). There was a trend to increased BAL neutrophils at day 4 compared with baseline (P = 0.076). BAL HNP 1-3 was positively correlated with BAL neutrophil numbers at day 4. There were no correlations between clinical parameters and HNP1-3 or IL-8 levels.

CONCLUSIONS

We propose that RV infection in asthma leads to increased release of CXCL8/IL-8, attracting neutrophils into the airways where they release HNP 1-3, which further enhances airway neutrophilia. Strategies to inhibit CXCL8/IL-8 may be useful in treatment of virus-induced asthma exacerbations.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusions

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

Formoterol and budesonide inhibit rhinovirus infection and cytokine production in primary cultures of human tracheal epithelial cells

BACKGROUND

Long-acting β(2) agonists (LABAs) and inhaled corticosteroids (ICSs) reduce the frequency of exacerbations of chronic obstructive pulmonary disease and bronchial asthma. However, inhibitory effects of LABAs and ICSs on the replication of rhinovirus (RV), the major cause of exacerbations, have not been demonstrated.

METHODS

Primary cultures of human tracheal epithelial cells were infected with a major group RV, type 14 rhinovirus (RV14), to examine the effects of formoterol and budesonide on RV infection and infection-induced airway inflammation.

RESULTS

Treatment with formoterol and budesonide 72 h before and after RV14 infection reduced RV14 titers and cytokine concentrations, including interleukin (IL)-1β, IL-6 and IL-8, in supernatants and viral RNA within cells. Formoterol and budesonide reduced mRNA expression and protein concentration of intercellular adhesion molecule-1 (ICAM-1), the receptor for RV14. Formoterol reduced the number and fluorescence intensity of acidic endosomes through which RV RNA enters the cytoplasm. Formoterol and budesonide reduced the activation of the nuclear factor kappa-B protein p65 in nuclear extracts. The effects of formoterol plus budesonide were additive with respect to RV14 replication, cytokine production, ICAM-1 expression, acidic endosome fluorescence intensity, and p65 activation. The selective β(2)-adrenergic receptor antagonist, ICI 118551 [erythro-dl-1-(7-methylindan-4-yloxy)-3-isopropylaminobutan-2-ol], reversed the inhibitory effects of formoterol on RV14 titers and RNA levels, the susceptibility of cells to RV14 infection, cytokine production, acidic endosomes, ICAM-1 expression, and p65 activation.

CONCLUSIONS

Formoterol and budesonide may inhibit RV infection by reducing the ICAM-1 levels and/or acidic endosomes and modulate airway inflammation associated with RV infections.

Determinants Of Oral corticosteroid Responsiveness in Wheezing Asthmatic Youth (DOORWAY): protocol for a prospective multicentre cohort study of children with acute moderate-to-severe asthma exacerbations

INTRODUCTION

Oral corticosteroids are the cornerstone of acute asthma management in the emergency department. Recent evidence has raised doubts about the efficacy of this treatment in preschool-aged children with viral-induced wheezing and in smoking adults. The aims of the study were to: (1) document the magnitude of response to oral corticosteroids in children presenting to the emergency department with moderate or severe asthma; (2) quantify potential determinants of response to corticosteroids and (3) explore the role of gene polymorphisms associated with the responsiveness to corticosteroids.

METHODS AND ANALYSIS

The design is a prospective cohort study of 1008 children aged 1-17 years meeting a strict definition of asthma and presenting with a clinical score of ≥4 on the validated Pediatric Respiratory Assessment Measure. All children will receive standardised severity-specific treatment with prednisone/prednisolone and cointerventions (salbutamol with/without ipratropium bromide). Determinants, namely viral aetiology, environmental tobacco smoke and single nucleotide polymorphism, will be objectively documented. The primary efficacy endpoint is the failure of emergency department (ED) management within 72 h of the ED visit. Secondary endpoints include other measures of asthma severity and time to recovery within 7 days of the index visit. The study has 80% power for detecting a risk difference of 7.5% associated with each determinant from a baseline risk of 21%, at an α of 0.05.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from all participating institutions. An impaired response to systemic steroids in certain subgroups will challenge the current standard of practice and call for the immediate search for better approaches. A potential host-environment interaction will broaden our understanding of corticosteroid responsiveness in children. Documentation of similar effectiveness of corticosteroids across determinants will provide the needed reassurance regarding current treatment recommendations.

RESULTS

Results will be disseminated at international conferences and manuscripts targeted at emergency physicians, paediatricians, geneticists and respirologists.

TRIAL REGISTRATION NUMBER

This study is registered at Clinicaltrials.gov (NCT02013076).

Rhinovirus exacerbates house-dust-mite induced lung disease in adult mice

Human rhinovirus is a key viral trigger for asthma exacerbations. To date, murine studies investigating rhinovirus-induced exacerbation of allergic airways disease have employed systemic sensitisation/intranasal challenge with ovalbumin. In this study, we combined human-rhinovirus infection with a clinically relevant mouse model of aero-allergen exposure using house-dust-mite in an attempt to more accurately understand the links between human-rhinovirus infection and exacerbations of asthma. Adult BALB/c mice were intranasally exposed to low-dose house-dust-mite (or vehicle) daily for 10 days. On day 9, mice were inoculated with human-rhinovirus-1B (or UV-inactivated human-rhinovirus-1B). Forty-eight hours after inoculation, we assessed bronchoalveolar cellular inflammation, levels of relevant cytokines/serum antibodies, lung function and responsiveness/sensitivity to methacholine. House-dust-mite exposure did not result in a classical TH₂-driven response, but was more representative of noneosinophilic asthma. However, there were significant effects of house-dust-mite exposure on most of the parameters measured including increased cellular inflammation (primarily macrophages and neutrophils), increased total IgE and house-dust-mite-specific IgG₁ and increased responsiveness/sensitivity to methacholine. There were limited effects of human-rhinovirus-1B infection alone, and the combination of the two insults resulted in additive increases in neutrophil levels and lung parenchymal responses to methacholine (tissue elastance). We conclude that acute rhinovirus infection exacerbates house-dust-mite-induced lung disease in adult mice. The similarity of our results using the naturally occurring allergen house-dust-mite, to previous studies using ovalbumin, suggests that the exacerbation of allergic airways disease by rhinovirus infection could act via multiple or conserved mechanisms.

Bronchodilator response as a hallmark of uncontrolled asthma: a randomised clinical trial

INTRODUCTION

The goal of this study is to determine whether bronchodilator (BD) response can be used as a reliable measure of asthma control by analyzing the effects of a short course of oral corticosteroids (OC) or placebo (P) on spirometry, sputum cytology and BD response in controlled asthma patients scoring less than 1.5 on the ACQ5.

METHODS

Seventy patients with moderate to severe asthma who were undergoing combination therapy and were considered to be controlled based on ACQ5 scores, but who exhibited persistent positive BD response, were randomly assigned to two groups, one receiving OC and the other P. Patients were evaluated before and after 2 weeks of treatment. Intervention response (comparison of FEV(1) before and after OC or P treatment) was used as a measure of intervention efficacy, with values equal to or greater than 200 mL considered positive.

RESULTS

Patients who received OC showed significant improvement in FEV(1), and no longer exhibited a positive BD response. Those in the P group showed no change. In addition, sputum eosinophil counts significantly decreased in the OC group.

CONCLUSIONS

BD response can be used as a reliable measure of asthma control. This study suggests that ACQ5 scores alone are not sufficient to fully assess asthma control, and that BD response should be included as an essential measurement in any algorithm of asthma control evaluation.

Tulobuterol inhibits rhinovirus infection in primary cultures of human tracheal epithelial cells

A transdermal patch preparation of the β2 agonist tulobuterol has been designed to yield sustained β2 agonistic effects and has been used as a long-acting β2 agonist (LABA) in Japan. LABAs reduce the frequency of exacerbations of chronic obstructive pulmonary disease and bronchial asthma. However, inhibitory effects of LABAs on the replication of rhinovirus (RV), the major cause of exacerbations, have not been demonstrated. To examine the effects of tulobuterol on RV replication and on the production of the replication-induced pro-inflammatory cytokines, human tracheal epithelial cells were infected with a major group RV, type 14 rhinovirus (RV14). Tulobuterol reduced the RV14 titers and RNA levels; the concentrations of cytokines, including interleukin (IL)-1β, IL-6, and IL-8, in the supernatants; and susceptibility to RV14 infection. Tulobuterol reduced the expression of intercellular adhesion molecule-1 (ICAM-1), the receptor for RV14, and the number of acidic endosomes in the cells in which RV14 RNA enters the cytoplasm. Tulobuterol inhibited the activation of nuclear factor kappa B (NF-κB) proteins in nuclear extracts. A selective β2-adrenergic receptor antagonist, ICI 118551 [erythro-dl-1-(7-methylindan-4-yloxy)-3-isopropylaminobutan-2-ol], reversed the inhibitory effects of tulobuterol on the RV14 titers and RNA levels, the susceptibility to RV14 infection, cytokine production, and ICAM-1 expression. Tulobuterol may inhibit RV replication by reducing ICAM-1 expression and acidic endosomes and modulate airway inflammation during RV replication.

Targeted therapy of bronchitis in obstructive airway diseases

Guidelines for the management of obstructive airway diseases do not emphasize the measurement of bronchitis to indicate appropriate treatments or monitor response to treatment. Bronchitis is the central component of airway diseases and contributes to symptoms, physiological and structural abnormalities. It can be measured directly and reliably by quantitative assay of spontaneous or induced sputum. The measurement is reproducible, valid, and responsive to treatment and to changes in disease status. Bronchitis may be eosinophilic, neutrophilic, mixed, or paucigranulocytic (eosinophils and neutrophils not elevated). Eosinophilic bronchitis is usually a Th2 driven process and therefore a sputum eosinophilia of greater than 3% usually indicates a response to treatment with corticosteroids or novel therapies directed against Th2 cytokines such as IL-4, IL-5 and IL-13. Neutrophilic bronchitis which is a non-Th2 driven disease is generally a predictor of response to antibiotics and may be a predictor to therapies targeted at pathways that lead to neutrophil recruitment such as IL-8 (eg anti-CXCR2), IL-17 (eg anti-IL17) etc. Paucigranulocytic disease may not warrant anti-inflammatory therapy. Several novel monoclonals and small molecule antagonists have been evaluated in clinical trials with variable results and several more are likely to be discovered in the near future. The success of these agents will depend on appropriate patient selection by accurate phenotyping or characterization of bronchitis.

Impaired innate interferon induction in severe therapy resistant atopic asthmatic children

Deficient type I interferon-β and type III interferon-λ induction by rhinoviruses has previously been reported in mild/moderate atopic asthmatic adults. No studies have yet investigated if this occurs in severe therapy resistant asthma (STRA). Here, we show that compared with non-allergic healthy control children, bronchial epithelial cells cultured ex vivo from severe therapy resistant atopic asthmatic children have profoundly impaired interferon-β and interferon-λ mRNA and protein in response to rhinovirus (RV) and polyIC stimulation. Severe treatment resistant asthmatics also exhibited increased virus load, which negatively correlated with interferon mRNA levels. Furthermore, uninfected cells from severe therapy resistant asthmatic children showed lower levels of Toll-like receptor-3 mRNA and reduced retinoic acid inducible gene and melanoma differentiation-associated gene 5 mRNA after RV stimulation. These data expand on the original work, suggesting that the innate anti-viral response to RVs is impaired in asthmatic tissues and demonstrate that this is a feature of STRA.

Nasal cytokine responses to natural colds in asthmatic children

Background

The mechanisms by which viruses induce asthma exacerbations are not well understood.

Objective

We characterized fluctuations in nasal aspirate cytokines during naturally occurring respiratory viral infections in children with asthma.

Methods

Sixteen children underwent home collections of nasal aspirates when they were without cold symptoms and again during self‐reported respiratory illnesses. The presence of viral infection was ascertained by multiplex PCR. Cytokines were measured using multiplex immune assay. mRNA expression for selected markers of viral infection was measured using RT‐PCR. A cumulative respiratory symptom score was calculated for each day of measurement. Generalized estimated equations were used to evaluate associations between viral infection and marker elevation, and between marker elevation and symptom score.

Results

The 16 patients completed a total of 37 weeks of assessment (15 ‘well’ weeks; 22 self‐assessed ‘sick’ weeks). Viral infections were detected in 3 of the ‘well’ weeks and 17 of the ‘sick’ weeks (10 rhinovirus, three coronavirus, two influenza A, two influenza B, two respiratory syncytial virus, one parainfluenza). Compared to virus‐negative well weeks, nasal aspirate IFN‐γ, CXCL8/IL‐8, CXCL10/IP‐10, CCL5/RANTES, CCL11/eotaxin‐1, CCL2/MCP‐1, CCL4/MIP‐1β, CCL7/MCP‐3, and CCL20/MIP3α protein levels increased during virus‐positive sick weeks. Only a subset of cytokines (IFN‐γ, CXCL8, CCL2, CCL4, CCL5, and CCL20) correlated with self‐reported respiratory tract symptoms. While many aspirates were dilute and showed no mRNA signal, viral infection significantly increased the number of samples that were positive for IFN‐λ1, IFN‐λ2/3, TLR3, RIG‐I, and IRF7 mRNA.

Conclusions and clinical relevance

We conclude that in children with asthma, naturally occurring viral infections apparently induce a robust innate immune response including expression of specific chemokines, IFNs, and IFN‐responsive genes.

Effect of formoterol on eosinophil trans-basement membrane migration induced by interleukin-8-stimulated neutrophils

BACKGROUND

Neutrophils are often increased in the airways of either chronic severe asthma or acute exacerbations. Neutrophils that have migrated in response to interleukin-8 (IL-8) may lead eosinophils to accumulate in the airways of patients with asthma and possibly aggravate the disease. In this study, we investigated whether formoterol modified the trans-basement membrane migration (TBM) of eosinophils stimulated with neutrophils and IL-8.

METHODS

Neutrophils and eosinophils were isolated from peripheral blood obtained from healthy donors. Eosinophil TBM was examined using a modified Boyden's chamber technique. Neutrophils were preincubated with or without formoterol (0.1 μM) at 37°C for 30 min. Eosinophils were added to the upper compartment of a chamber with a Matrigel-coated transwell insert. Medium containing preincubated neutrophils and IL-8 was added to the lower compartment of the chamber. After a 90-minute incubation, the eosinophils that had migrated into the lower chamber were calculated using eosinophil peroxidase assays.

RESULTS

A combination of neutrophils and IL-8 significantly induced the eosinophil TBM; formoterol alone had no effect. However, formoterol modestly but significantly attenuated the TBM of eosinophils stimulated with neutrophils and IL-8.

CONCLUSION

These results suggest that formoterol may act as a therapeutic agent on enhanced eosinophilic inflammation in acute exacerbation or persistent, severe asthma. The effect of formoterol likely involves the inhibition of neutrophil activation.

Cytokine expression profiles of immune imbalance in post-mononucleosis chronic fatigue

Background

As Chronic Fatigue Syndrome (CFS) has been known to follow Epstein-Bar virus (EBV) and other systemic infections; our objective was to describe differences in immune activation in post-infective CFS (PI-CFS) patients and recovered controls. We studied 301 adolescents prospectively over 24 months following the diagnosis of monospot-positive infectious mononucleosis (IM). We found an incidence of CFS at 6, 12 and 24 months of 13%, 7% and 4% respectively.

Methods

Using chemiluminescent imaging we measured the concentrations of IL-1a, 1b, 2, 4, 5, 6, 8, 10, 12 (p70), 13, 15, 17 and 23, IFN-γ, TNF-α and TNF-β in duplicate plasma samples available in bio-bank from 9 PI-CFS subjects and 12 recovered controls at 24 months post-infection.

Results

Standard comparative analysis indicated significant differences in IL-8 and 23 across subject groups. In constructing a linear classification model IL-6, 8 and 23 were selected by two different statistical approaches as discriminating features, with IL-1a, IL-2 and IFN-γ also selected in one model or the other. This supported an assignment accuracy of better than 80% at a confidence level of 0.95 into PI-CFS versus recovered controls.

Conclusion

These results suggest that co-expression patterns in as few as 5 cytokines associated with Th17 function may hold promise as a tool for the diagnosis of post-infectious CFS.

How to diagnose and phenotype asthma

Asthma has been described as a chronic disease of the airways characterized by variable airflow obstruction, airway hyperresponsiveness, and airway inflammation. This review discusses the diagnosis and phenotyping of asthma, with a special emphasis on phenotyping based on the nature of cellular inflammation and radiological imaging and how this could be used to direct the treatment of asthma and, in the future, to apply specifically directed therapies to specific phenotypes.

The microbiology of asthma

Asthma remains an important human disease that is responsible for substantial worldwide morbidity and mortality. The causes of asthma are multifactorial and include a complex mix of environmental, immunological and host genetic factors. In addition, epidemiological studies show strong associations between asthma and infection with respiratory pathogens, including common respiratory viruses such as rhinoviruses, human respiratory syncytial virus, adenoviruses, coronaviruses and influenza viruses, as well as bacteria (including atypical bacteria) and fungi. In this Review, we describe the many roles of microorganisms in the risk of developing asthma and in the pathogenesis of and protection against the disease, and we discuss the mechanisms by which infections affect the severity and prevalence of asthma.

A mechanistic role for type III IFN-λ1 in asthma exacerbations mediated by human rhinoviruses

RATIONALE

Human rhinoviruses (HRV) are the leading cause of upper respiratory infections and have been postulated to trigger asthma exacerbations. However, whether HRV are detected during crises because upper respiratory infections often accompany asthma attacks, or because they specifically elicit exacerbations, is unclear. Moreover, although several hypotheses have been advanced to explain virus-induced exacerbations, their mechanism remains unclear.

OBJECTIVES

To determine the role of HRV in pediatric asthma exacerbations and the mechanisms mediating wheezing.

METHODS

We prospectively studied 409 children with asthma presenting with upper respiratory infection in the presence or absence of wheezing. Candidate viral and immune mediators of illness were compared among children with asthma with different degrees of severity of acute asthma.

MEASUREMENTS AND MAIN RESULTS

HRV infections specifically associated with asthma exacerbations, even after adjusting for relevant demographic and clinical variables defined a priori (odds ratio, 1.90; 95% confidence interval, 1.21-2.99; P = 0.005). No difference in virus titers, HRV species, and inflammatory or allergic molecules was observed between wheezing and nonwheezing children infected with HRV. Type III IFN-λ(1) levels were higher in wheezing children infected with HRV compared with nonwheezing (P < 0.001) and increased with worsening symptoms (P < 0.001). Moreover, after adjusting for IFN-λ(1), children with asthma infected with HRV were no longer more likely to wheeze than those who were HRV-negative (odds ratio, 1.18; 95% confidence interval, 0.57-2.46; P = 0.66).

CONCLUSIONS

Our findings suggest that HRV infections in children with asthma are specifically associated with acute wheezing, and that type III IFN-λ(1) responses mediate exacerbations caused by HRV. Modulation of IFN- λ(1) should be studied as a therapeutic target for exacerbations caused by HRV.

Lower airway rhinovirus burden and the seasonal risk of asthma exacerbation

RATIONALE

Most asthma exacerbations are initiated by viral upper respiratory illnesses. It is unclear whether human rhinovirus (HRV)–induced exacerbations are associated with greater viral replication and neutrophilic inflammation compared with HRV colds.

OBJECTIVES

To evaluate viral strain and load in a prospective asthma cohort during a natural cold.

METHODS

Adults were enrolled at the first sign of a cold, with daily monitoring of symptoms, medication use, and peak expiratory flow rate until resolution. Serial nasal lavage and induced sputum samples were assessed for viral copy number and inflammatory cell counts.

MEASUREMENTS AND MAIN RESULTS

A total of 52 persons with asthma and 14 control subjects without atopy or asthma were studied for over 10 weeks per subject on average; 25 participants developed an asthma exacerbation. Detection of HRVs in the preceding 5 days was the most common attributable exposure related to exacerbation. Compared with other infections, those by a minor group A HRV were 4.4- fold more likely to cause exacerbation (P = 0.038). Overall, sputum neutrophils and the burden of rhinovirus in the lower airway were similar in control subjects without atopy and the asthma group. However, among HRV-infected participants with asthma, exacerbations were associated with greater sputum neutrophil counts (P = 0.005).

CONCLUSIONS

HRV infection is a frequent cause of exacerbations in adults with asthma and a cold, and there may be group-specific differences in severity of these events. The absence of large differences in viral burden among groups suggests differential lower airway sensitization to the effects of neutrophilic inflammation in the patients having exacerbations.

A study of elevated interleukin-8 (CXCL8) and detection of leukocyte migration inhibitory activity in patients allergic to beta-lactam antibiotics

BACKGROUND

The leukocyte migration test (LMT) is effective in identifying the causative drug in drug allergies. Both leukocyte migration activating activity (LMAA) and leukocyte migration inhibitory activity (LMIA) are involved in the development of drug allergies. However, no cytokines associated with LMIA have been identified to date. Because CXCL8 played an important role in neutrophil infiltration and activation, we performed the LMT and measured CXCL8 levels in patients with hypersensitivity to beta-lactam antibiotics (beta-lactams) and antipyretic analgesics (APAs) and investigated the pathogenic mechanism of hypersensitivity to these drugs.

METHODS

The LMT was performed according to an improved version of the agarose plate method and CXCL8 levels in the reacted solution that had been stored as described were measured using a solid-phase sandwich enzyme-linked immunosorbent assay.

RESULTS

Migration index (MI) values for the LMT were 77.7 ± 11.7 for patients with hypersensitivity to beta-lactams and 83.6 ± 1.9 for those with hypersensitivity to APAs. The CXCL8 concentrations were significantly higher in patients after beta-lactams administration (175.9 ± 71.2 ng/mL) than those without beta-lactams administration (48.3 ± 34.9 ng/mL). The CXCL8 concentrations were significantly lower in patients after APAs administration (41.7 ± 24.3 ng/mL) than those without APAs administration (63.1 ± 30.2 ng/mL).

CONCLUSIONS

Increased CXCL8 levels produced by beta-lactams administration were accompanied by LMIA. CXCL8 may be involved in LMIA and play a role in beta-lactam allergies. In contrast, the LMIA detected in patients with allergies to APAs may be a cytokine or chemokine other than CXCL8.

IFN-γ-inducible protein of 10 kDa upregulates the effector functions of eosinophils through β2 integrin and CXCR3

BACKGROUND

Eosinophils play an important role in the pathogenesis of bronchial asthma and its exacerbation. Recent reports suggest the involvement of IFN-γ-inducible protein of 10 kDa (IP-10) in virus-induced asthma exacerbation. The objective of this study was to examine whether CXCR3 ligands including IP-10 modify the effector functions of eosinophils.

METHODS

Eosinophils isolated from the blood of healthy donors were stimulated with CXCR3 ligands and their adhesion to rh-ICAM-1 was then measured using eosinophil peroxidase assays. The generation of eosinophil superoxide anion (O2-) was examined based on the superoxide dismutase-inhibitable reduction of cytochrome C. Eosinophil-derived neurotoxin (EDN) release was evaluated to determine whether CXCR3 ligands induced eosinophil degranulation. Cytokine and chemokine production by eosinophils was examined using a Bio-plex assay.

RESULTS

Eosinophil adhesion to ICAM-1 was significantly enhanced by IP-10, which also significantly induced eosinophil O2- generation in the presence of ICAM-1. Both the enhanced adhesion and O2- generation were inhibited by an anti-β2 integrin mAb or an anti-CXCR3 mAb. Other CXCR3 ligands, such as monokine induced by IFN-γ (Mig) and IFN-inducible T cell α chemoattractant (I-TAC), also induced eosinophil adhesion and O2- generation in the presence of ICAM-1. IP-10, but not Mig or I-TAC, increased the release of EDN. IP-10 increased the production of a number of cytokines and chemokines by eosinophils.

CONCLUSIONS

These findings suggest that CXCR3 ligands such as IP-10 can directly upregulate the effector functions of eosinophils. These effects might be involved in the activation and infiltration of eosinophils in the airway of asthma, especially in virus-induced asthma exacerbation.

T lymphocytes promote the antiviral and inflammatory responses of airway epithelial cells

HYPOTHESIS

T cells modulate the antiviral and inflammatory responses of airway epithelial cells to human rhinoviruses (HRV).

METHODS

Differentiated primary human nasal epithelial cells (HNEC) grown on collagen-coated filters were exposed apically to HRV14 for 6 h, washed thoroughly and co-cultured with anti-CD3/CD28 activated T cells added in the basolateral compartment for 40 h.

RESULTS

HRV14 did not induce IFNγ, NOS2, CXCL8 and IL-6 in HNEC, but enhanced expression of the T cell attractant CXCL10. On the other hand, HNEC co-cultured with activated T cells produced CXCL10 at a level several orders of magnitude higher than that induced by HRV14. Albeit to a much lower degree, activated T cells also induced CXCL8, IL-6 and NOS2. Anti-IFNγ antibodies and TNF soluble receptor completely blocked CXCL10 upregulation. Furthermore, a significant correlation was observed between epithelial CXCL10 mRNA expression and the amounts of IFNγ and TNF secreted by T cells. Likewise, increasing numbers of T cells to a constant number of HNEC in co-cultures resulted in increasing epithelial CXCL10 production, attaining a plateau at high IFNγ and TNF levels. Hence, HNEC activation by T cells is induced mainly by IFNγ and/or TNF. Activated T cells also markedly inhibited viral replication in HNEC, partially through activation of the nitric oxide pathway.

CONCLUSION

Cross-talk between T cells and HNEC results in activation of the latter and increases their contribution to airway inflammation and virus clearance.

Steroid responsiveness and wheezing phenotypes

Oral corticosteroids are the cornerstone of management of acute moderate or severe asthma whilst preventive inhaled corticosteroids are the mainstay of the preventive management of children with asthma. Yet, variation in the magnitude of response to corticosteroids has been observed. There is increasing evidence that preschool-aged children with viral-induced asthma may display a certain degree of corticosteroid resistance, requiring higher doses of corticosteroids to overcome it. The identification of determinants of responsiveness is complicated by design issues, including heterogeneous populations of children with asthma and bronchiolitis or of children with viral-induced and multi-trigger asthma phenotypes in published trials. Potential key determinants of responsiveness may include age, trigger, phenotype, tobacco smoke exposure and genotype. The mechanistic pathway for corticoresistance may originate from a gene-environment interaction, leading to non-eosinophilic airway inflammation. The clinician should carefully confirm the diagnosis of asthma and ascertain the phenotype to select appropriate phenotype-specific therapy.

Alcohol fixation of induced sputum samples for applications in rural communities

BACKGROUND

Sputum induction is a tool recommended for the assessment of airway inflammation and disease management. Currently, its use is limited because samples need to be processed within 3 h of induction (ie, while cells are viable); therefore, this procedure is unavailable to most clinicians.

OBJECTIVE

To develop a fixation method for induced sputum samples that allows for a delay in processing while maintaining sample integrity and not altering the standard processing method.

METHODS

Sputum samples were collected and split into three portions: a fresh sample processed using the routine method (within 3 h, using dithiothreitol); fixation in alcohol followed by delayed processing using the routine method (within 48 h to 72 h, using dithiothreitol); and fixation in formaldehyde followed by delayed processing using an alternative method (within 48 h to 72 h, using proteolysis). For each method, cytospins were prepared and differential cell counts were performed.

RESULTS

Fixation in alcohol provides accurate measures of eosinophils and macrophages, but not neutrophils. Formaldehyde fixation provides accurate measures of neutrophils and macrophages, but not eosinophils.

DISCUSSION

Alcohol fixation is a superior method for eosinophil quantification. It requires alteration of standardized methods for sputum sample processing and should be recommended for monitoring eosinophilic airway disease in settings where immediate processing of a sputum sample is not possible.