Rhinovirus and serum IgE are associated with acute asthma exacerbation severity in children

The Direct and Indirect Role of IgE on Airway Epithelium in Asthma

Asthma is a chronic airway inflammatory disorder, affecting over 350 million people worldwide, with allergic asthma being the most common form of the disease. Allergic asthma is characterized by a type 2 (T2) inflammatory response triggered by numerous allergens beginning in the airway epithelium, which acts as a physical barrier to allergens as well as other external irritants including infectious agents, and atmospheric pollutants. T2 inflammation is propagated by several key cell types including T helper 2 (Th2) cells, eosinophils, mast cells, and B cells. Immunoglobulin E (IgE), produced by B cells, is a key molecule in allergic airway disease and plays an important role in T2 inflammation, as well as being central to remodeling processes within the airway epithelium. Blocking IgE with omalizumab has been shown to be efficacious in treating allergic asthma however, the role of IgE on airway epithelial cells is less communicated. Developing a deeper explanation of the complex network of interactions between IgE and the airway epithelium will facilitate an improved understanding of asthma pathophysiology. This review discusses the indirect and direct roles of IgE on airway epithelial cells, with a focus on allergic asthma disease.

Biomarkers of type 2 and non-type 2 inflammation in asthma exacerbations

Introduction

In adult-onset asthma, two major endotypes have been proposed: T2 with eosinophilia and non-T2 characterised by neutrophils and interleukin (IL)-17. The objective of the study was to examine the endotype marker profile in patients with severe asthma who were hospitalized for exacerbations, with a focus on differentiating between viral and non-viral triggers.

Material and methods

Forty-nine patients with asthma, admitted for exacerbations, and 51 healthy controls (HCs) were recruited. We further categorized the exacerbated asthma patients into two groups: non-viral infected (n = 38) and viral infected (n = 11) groups. Blood was drawn and a nasopharyngeal swab taken at the time of admission and eosinophil numbers, eosinophil cationic protein (ECP), immuno- globulin E (IgE), tryptase and viral infection were determined. Additionally, levels of IL-17, IL-33 and IL-31 were assessed.

Results

The majority of patients had adult onset asthma (age of diagnosis, 42.8 ±16.1) with a duration of 7.7 ±10.8 years, 24.5% being atopic. Patients had higher levels of eosinophils, ECP and IgE than healthy controls (eosinophils, p = 0.003; ECP and IgE, p = 0.0001). Immunohistochemistry confirmed eosinophils as a source of ECP. Tryptase (p = 0.0001), IL-17 (p = 0.0005), IL-31 (p = 0.0001) and IL-33 (p = 0.0002) were also higher in patients than controls. ECP correlated with tryptase (r = 0.08, p = 0.62). IL-17 showed the best correlation with other mediators, including ECP (r = 0.35, p = 0.24), tryptase (r = 0.69, p = 0.0001), IgE (r = 0.50, p = 0.0001), IL-33 (r = 0.95, p = 0.0001) and IL-31 (r = 0.89, p = 0.0001). IgE, IL-17, and IL-31 had a high AUC when differentiating those with severe and non-severe asthma. The group with exacerbated viral infection showed elevated levels of serum IL-17 and IL-31 compared to the non-infected group.

Conclusions

Patients with asthmatic exacerbations were found to have higher levels of both T2 and non-T2 inflammatory markers than healthy controls. In the study, levels of IgE, IL-17, and IL-31 differentiated between patients with severe and non-severe asthma. The last two cytokines were also able to distinguish between exacerbated asthma caused by viral infection and exacerbated asthma caused by non-viral infection.

Histamine-releasing factor in severe asthma and rhinovirus-associated asthma exacerbation

BACKGROUND

Histamine-releasing factor (HRF) is implicated in allergic diseases. We previously showed its pathogenic role in murine models of asthma.

OBJECTIVE

We aim to present data analysis from 3 separate human samples (sera samples from asthmatic patients, nasal washings from rhinovirus [RV]-infected individuals, and sera samples from patients with RV-induced asthma exacerbation) and 1 mouse sample to investigate correlates of HRF function in asthma and virus-induced asthma exacerbations.

METHODS

Total IgE and HRF-reactive IgE/IgG as well as HRF in sera from patients with mild/moderate asthma or severe asthma (SA) and healthy controls (HCs) were quantified by ELISA. HRF secretion in culture media from RV-infected adenovirus-12 SV40 hybrid virus transformed human bronchial epithelial cells and in nasal washings from experimentally RV-infected subjects was analyzed by Western blotting. HRF-reactive IgE/IgG levels in longitudinal serum samples from patients with asthma exacerbations were also quantified.

RESULTS

HRF-reactive IgE and total IgE levels were higher in patients with SA than in HCs, whereas HRF-reactive IgG (and IgG1) level was lower in asthmatic patients versus HCs. In comparison with HRF-reactive IgElow asthmatic patients, HRF-reactive IgEhigh asthmatic patients had a tendency to release more tryptase and prostaglandin D2 on anti-IgE stimulation of bronchoalveolar lavage cells. RV infection induced HRF secretion from adenovirus-12 SV40 hybrid virus transformed bronchial epithelial cells, and intranasal RV infection of human subjects induced increased HRF secretion in nasal washes. Asthmatic patients had higher levels of HRF-reactive IgE at the time of asthma exacerbations associated with RV infection, compared with those after the resolution. This phenomenon was not seen in asthma exacerbations without viral infections.

CONCLUSIONS

HRF-reactive IgE is higher in patients with SA. RV infection induces HRF secretion from respiratory epithelial cells both in vitro and in vivo. These results suggest the role of HRF in asthma severity and RV-induced asthma exacerbation.

Asthma: The Use of Animal Models and Their Translational Utility

Asthma is characterized by chronic lower airway inflammation that results in airway remodeling, which can lead to a permanent decrease in lung function. The pathophysiology driving the development of asthma is complex and heterogenous. Animal models have been and continue to be essential for the discovery of molecular pathways driving the pathophysiology of asthma and novel therapeutic approaches. Animal models of asthma may be induced or naturally occurring. Species used to study asthma include mouse, rat, guinea pig, cat, dog, sheep, horse, and nonhuman primate. Some of the aspects to consider when evaluating any of these asthma models are cost, labor, reagent availability, regulatory burden, relevance to natural disease in humans, type of lower airway inflammation, biological samples available for testing, and ultimately whether the model can answer the research question(s). This review aims to discuss the animal models most available for asthma investigation, with an emphasis on describing the inciting antigen/allergen, inflammatory response induced, and its translation to human asthma.

Evaluation of an Immunoglobulin E Capture Enzyme-Linked Immunosorbent Assay for the Early Diagnosis of Dengue

Dengue virus (DENV) is the etiological agent of dengue, the most important mosquito-transmitted viral disease of humans worldwide. Enzyme-linked immunosorbent assays (ELISAs) designed to detect DENV IgM are commonly used for dengue diagnosis. However, DENV IgM is not reliably detected until ≥4 days after illness onset. Reverse transcription-polymerase chain reaction (RT-PCR) can diagnose early dengue but requires specialized equipment, reagents, and trained personnel. Additional diagnostic tools are needed. Limited work has been performed to determine whether IgE-based assays can be used for the early detection of vector-borne viral diseases, including dengue. In this study, we determined the efficacy of a DENV IgE capture ELISA for the detection of early dengue. Sera were collected within the first 4 days of illness onset from 117 patients with laboratory-confirmed dengue, as determined by DENV-specific RT-PCR. The serotypes responsible for the infections were DENV-1 and DENV-2 (57 and 60 patients, respectively). Sera were also collected from 113 dengue-negative individuals with febrile illness of undetermined etiology and 30 healthy controls. The capture ELISA detected DENV IgE in 97 (82.9%) confirmed dengue patients and none of the healthy controls. There was a high false positivity rate (22.1%) among the febrile non-dengue patients. In conclusion, we provide evidence that IgE capture assays have the potential to be explored for early diagnosis of dengue, but further research is necessary to address the possible false positivity rate among patients with other febrile illnesses.

A retrospective study of SARS-CoV-2 antibodies in children with allergies

BACKGROUND

The dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children are continually changing. We conducted a survey of pediatric allergy patients attending our department to determine the prevalence of antibodies against SARS-CoV-2 in children.

METHODS

A retrospective study was performed among children aged <11 years, referred to a pediatric allergy department between February 2020 and January 2022 with a chief complaint of allergy. The data of children with blood examination findings were retrospectively studied. Qualitative testing for anti-SARS-CoV-2 IgG and IgM antibodies was performed using a SARS-CoV-2 rapid antibody test. Participants were retested 1 year later to evaluate changes in antibody levels.

RESULTS

In total, 310 patients with a median age of 26 months (interquartile range: 11.6-58.4 months) and male/female ratio of 1.31 were included. A total of 32 patients tested positive for anti-SARS-CoV-2 IgG or IgM antibodies. No differences were observed in the severity of allergic disease. The prevalence of antibodies was higher among children enrolled in preschool or school (odds ratio: 13.19, 95% confidence interval; 2.30-249.7). A total of 66.7% of patients underwent follow-up testing. The antibody positivity rate increased between the first and second testing, but this was not related to the number of medical visits or the severity of allergic disease.

CONCLUSION

Antibody prevalence in children was low but increased during the study period. The majority of children who tested positive for SARS-CoV-2 antibodies did not have a history of coronavirus disease 2019, suggesting that most infections were subclinical.

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.

Novel potential treatable traits in asthma: Where is the research taking us?

Asthma is a complex, heterogeneous disease in which the underlying mechanisms are not fully understood. Patients are often grouped into phenotypes (based on clinical, biologic, and physiologic characteristics) and endotypes (based on distinct genetic or molecular mechanisms). Recently, patients with asthma have been broadly split into 2 phenotypes based on their levels of type 2 inflammation: type 2 and non-type 2 asthma. However, this approach is likely oversimplified, and our understanding of the non-type 2 mechanisms in asthma remains extremely limited. A better understanding of asthma phenotypes and endotypes may assist in development of drugs for new therapeutic targets in asthma. One approach is to identify "treatable traits," which are specific patient characteristics related to phenotypes and endotypes that can be targeted by therapies. This review will focus on emerging treatable traits in asthma and aim to describe novel patient subgroups and endotypes that may represent the next step in the search for new therapeutic approaches.

Immunoglobulin E-Dependent Activation of Immune Cells in Rhinovirus-Induced Asthma Exacerbation

Acute exacerbation is the major cause of asthma morbidity, mortality, and health-care costs. Respiratory viral infections, particularly rhinovirus (RV) infections, are associated with the majority of asthma exacerbations. The risk for bronchoconstriction with RV is associated with allergic sensitization and type 2 airway inflammation. The efficacy of the humanized anti-IgE monoclonal antibody omalizumab in treating asthma and reducing the frequency and severity of RV-induced asthma exacerbation is well-known. Despite these clinical data, mechanistic details of omalizumab's effects on RV-induced asthma exacerbation have not been well-defined for years due to the lack of appropriate animal models. In this Perspective, we discuss potential IgE-dependent roles of mast cells and dendritic cells in asthma exacerbations.

Serum IFN-γ-induced protein 10 (IP10/CXCL10): association with asthma exacerbations and severity in children

Objective: Asthma is a chronic disorder of the airways, in which chemokines coordinate airway inflammation and determine its severity. We aimed to study the chemokine interferon-γ-inducible protein 10 kDa (IP10/CXCL10), a member of the CXC receptor 3 (CXCR3) ligand family, at the protein level in the serum of children, to evaluate the association between CXCL10 and exacerbations of childhood asthma.Methods: Patients experiencing an asthma exacerbation (42 patients) and stable patients (43 patients) were investigated for serum CXCL10 levels.Results: Patients with an asthma exacerbation expressed significantly higher CXCL10 levels in the serum than stable patients (P = <0.001). Additionally, CXCL10 values were elevated in severe asthma compared with moderate and mild disease (P = <0.001). In patients experiencing asthma exacerbations, higher values of CXCL10 were observed in atopic patients compared with non-atopic patients (P = 0.027) and in uncontrolled and partly controlled patients compared with controlled patients (P = 0.046).Conclusions: CXCL10 is proposed as an inflammatory serum marker for asthma exacerbations and worsening asthma symptoms. The levels of CXCL10 are representative of the clinical severity of asthma.

The effect of COVID-19 on patients with chronic spontaneous urticaria treated with omalizumab and antihistamines: A cross-sectional, comparative study

Introduction

Chronic spontaneous urticaria (CSU) is defined as recurrent attacks of urticaria present for more than six weeks. The monoclonal anti‐immunoglobulin E antibody, omalizumab, was approved for the treatment of CSU in patients who remain refractory to H1‐antihistamines. Biologic agents are shown not to increase the risk of COVID‐19 infection in different studies.

Objective

In the present study, we aimed to determine the prevalance of COVID‐19 infection in relation to the age, gender, presence of other comorbidities, and treatment given for CSU.

Methods

We conducted a descriptive cross‐sectional study of 233 patients diagnosed with CSU in a tertiary referral hospital. Demographical data, treatment given for CSU, the presence of COVID‐19‐related symptoms, history of close contact to a person with COVID‐19 and COVID‐19 real‐time polymerase chain reaction (RT‐PCR) results were determined via a telephone survey and checked from medical data records.

Results

One hundred sixty patients were female; whereas 73 were male. The mean age was 44.76. Out of 233 patients with chronic urticaria, 125 had symptoms related to COVID‐19 infection. RT‐PCR testing for COVID‐19 was performed in 156 patients. Of 156 patients with COVID‐19 RT‐PCR test, RT‐PCR result was positive in 15 cases.

Conclusions

No statistically significant relationship was found between COVID‐19 RT‐PCR positivity and the type of treatment administered for chronic urticaria when the patients are divided into omalizumab ± oral antihistamines and only oral antihistamines treatment groups (p = 0.150). Omalizumab seems to be safe in the era of COVID‐19.

Immunological Aspects Related to Viral Infections in Severe Asthma and the Role of Omalizumab

Viral respiratory infections are recognized risk factors for the loss of control of allergic asthma and the induction of exacerbations, both in adults and children. Severe asthma is more susceptible to virus-induced asthma exacerbations, especially in the presence of high IgE levels. In the course of immune responses to viruses, an initial activation of innate immunity typically occurs and the production of type I and III interferons is essential in the control of viral spread. However, the Th2 inflammatory environment still appears to be protective against viral infections in general and in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections as well. As for now, literature data, although extremely limited and preliminary, show that severe asthma patients treated with biologics don't have an increased risk of SARS-CoV-2 infection or progression to severe forms compared to the non-asthmatic population. Omalizumab, an anti-IgE monoclonal antibody, exerts a profound cellular effect, which can stabilize the effector cells, and is becoming much more efficient from the point of view of innate immunity in contrasting respiratory viral infections. In addition to the antiviral effect, clinical efficacy and safety of this biological allow a great improvement in the management of asthma.

Rhinovirus and asthma: Challenges and opportunities

Human rhinoviruses (RVs) are the primary aetiological agent of the common cold. Generally, the associated infection is mild and self‐limiting, but may also be associated with bronchiolitis in infants, pneumonia in the immunocompromised and exacerbation in patients with pulmonary conditions such as asthma or chronic obstructive pulmonary disease. Viral infection accounts for as many as two thirds of asthma exacerbations in children and more than half in adults. Allergy and asthma are major risk factors for more frequent and severe RV‐related illnesses. The prevalence of RV‐induced wheezing will likely continue to increase given that asthma affects a significant proportion of the population, with allergic asthma accounting for the majority. Several new respiratory viruses and their subgroups have been discovered, with various degrees of relevance. This review will focus on RV infection in the context of the epidemiologic evidence, genetic variability, pathobiology, clinical studies in the context of asthma, differences with other viruses including COVID‐19 and current treatment interventions.

Mimicking Antigen-Driven Asthma in Rodent Models-How Close Can We Get?

Asthma is a heterogeneous disease with increasing prevalence worldwide characterized by chronic airway inflammation, increased mucus secretion and bronchial hyperresponsiveness. The phenotypic heterogeneity among asthmatic patients is accompanied by different endotypes, mainly Type 2 or non-Type 2. To investigate the pathomechanism of this complex disease many animal models have been developed, each trying to mimic specific aspects of the human disease. Rodents have classically been employed in animal models of asthma. The present review provides an overview of currently used Type 2 vs. non-Type 2 rodent asthma models, both acute and chronic. It further assesses the methods used to simulate disease development and exacerbations as well as to quantify allergic airway inflammation, including lung physiologic, cellular and molecular immunologic responses. Furthermore, the employment of genetically modified animals, which provide an in-depth understanding of the role of a variety of molecules, signaling pathways and receptors implicated in the development of this disease as well as humanized models of allergic inflammation, which have been recently developed to overcome differences between the rodent and human immune systems, are discussed. Nevertheless, differences between mice and humans should be carefully considered and limits of extrapolation should be wisely taken into account when translating experimental results into clinical use.

Prevention of Asthma: Targets for Intervention

Approximately 300 million people worldwide are estimated to be affected by asthma, and the number of patients affected is growing exponentially-with potential for an additional 100 million people affected by the condition by 2025. With this increasing burden of disease, there is high motivation to discover effective prevention strategies. Strategies aimed at stalling the atopic progression, modifying the microbiome, preventing respiratory viral infections, and reducing the impact of toxin/pollutant exposure through dietary supplements have had limited success in the prevention of asthma. This is likely because asthma is heterogenous and is influenced by different genetic and environmental factors. Genes underlie a predisposition to asthma and allergic sensitization, whereas exposure to allergens, respiratory infections, and pollution may modify asthma pathogenesis and the variation in severity seen among individuals. Future advances in asthma prevention may include a more personalized approach: genetic variations among susceptible individuals with distinct asthma phenotypes or different biomarkers of disease may help individualize prevention strategies and render them more . In this article, we summarize interventions that have been studied for the prevention of asthma and identify some of the clinical trials that are actively underway in asthma prevention.

Risk factors for intensive care admission in children with severe acute asthma in the Netherlands: a prospective multicentre study

Rationale

Severe acute asthma (SAA) can be fatal, but is often preventable. We previously observed in a retrospective cohort study, a three-fold increase in SAA paediatric intensive care (PICU) admissions between 2003 and 2013 in the Netherlands, with a significant increase during those years of numbers of children without treatment of inhaled corticosteroids (ICS).

Objectives

To determine whether steroid-naïve children are at higher risk of PICU admission among those hospitalised for SAA. Furthermore, we included the secondary risk factors tobacco smoke exposure, allergic sensitisation, previous admissions and viral infections.

Methods

A prospective, nationwide multicentre study of children with SAA (2–18 years) admitted to all Dutch PICUs and four general wards between 2016 and 2018. Potential risk factors for PICU admission were assessed using logistic regression analyses.

Measurements and main results

110 PICU and 111 general ward patients were included. The proportion of steroid-naïve children did not differ significantly between PICU and ward patients. PICU children were significantly older and more exposed to tobacco smoke, with symptoms >1 week prior to admission. Viral susceptibility was not a significant risk factor for PICU admission.

Conclusions

Children with SAA admitted to a PICU were comparable to those admitted to a general ward with respect to ICS treatment prior to admission. Preventable risk factors for PICU admission were >7 days of symptoms without adjustment of therapy and exposure to tobacco smoke. Physicians who treat children with asthma must be aware of these risk factors.

Preventable risk factors for PICU admission among those with severe acute asthma are >7 days of symptoms without adjustment of therapy and environmental exposure to tobacco smoke, underlining the importance of smoking cessation of caregivershttps://bit.ly/3ezPzxT

What the physicians should know about mast cells, dendritic cells, urticaria, and omalizumab during COVID-19 or asymptomatic infections due to SARS-CoV-2?

Coronavirus disease (COVID-19) pandemic presents several dermatological manifestations described in the present indexed literature, with around 700 cases reported until May 2020, some described as urticaria or urticarial rashes. Urticaria is constituted by evanescent erythematous-edematous lesions (wheals and flare), which does not persist in the same site for more than 24 to 48 hours and appears in other topographic localization, resolving without residual hyper pigmentation. During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, some cytokines are synthesized, including Interferon (IFN) type I, TNF-α, and chemokines which may induce mast cells (MCs) and basophils degranulation by mechanisms similar to the autoinflammatory monogenic or polygenic diseases. In this article, we discuss the spectrum of the urticaria and urticarial-like lesions in the COVID-19's era, besides other aspects related to innate and adaptative immune response to viral infections, interactions between dermal dendritic cells and MCs, and degranulation of MCs by different stimuli. Plasmacytoid dendritic cells share, in allergic patients, expression of the high-affinity IgE receptors on cell membranes and demonstrated a low pattern of type I IFN secretion in viral infections. We discuss the previous descriptions of the effects of omalizumab, a monoclonal antibody directed to IgE and high-affinity IgE receptors, to improve the IFN responses and enhance their antiviral effects.

Evolving concepts in how viruses impact asthma: A Work Group Report of the Microbes in Allergy Committee of the American Academy of Allergy, Asthma & Immunology

Over the past decade, there have been substantial advances in our understanding about how viral infections regulate asthma. Important lessons have been learned from birth cohort studies examining viral infections and subsequent asthma and from understanding the relationships between host genetics and viral infections, the contributions of respiratory viral infections to patterns of immune development, the impact of environmental exposure on the severity of viral infections, and how the viral genome influences host immune responses to viral infections. Further, there has been major progress in our knowledge about how bacteria regulate host immune responses in asthma pathogenesis. In this article, we also examine the dynamics of bacterial colonization of the respiratory tract during viral upper respiratory tract infection, in addition to the relationship of the gut and respiratory microbiomes with respiratory viral infections. Finally, we focus on potential interventions that could decrease virus-induced wheezing and asthma. There are emerging therapeutic options to decrease the severity of wheezing exacerbations caused by respiratory viral infections. Primary prevention is a major goal, and a strategy toward this end is considered.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Preventing the development of asthma: stopping the allergic march

PURPOSE OF REVIEW

To describe important precipitants of asthma and allergic disease, to highlight the links between these triggers and modifications within the immune system, and to examine innovative research regarding asthma prevention with focus on attenuating the atopic march.

RECENT FINDINGS

Allergen avoidance, allergen immunotherapy, IgE antagonists, prevention and treatment of respiratory infections, as well as management of gastrointestinal and respiratory dysbiosis have been considered as strategies in asthma prevention. Antenatal vitamin D supplementation in expectant mothers and aggressive control of atopic dermatitis to prevent the development of other allergic conditions were carefully studied as well.

SUMMARY

Asthma is a major cause of morbidity and lost productivity. Despite the tremendous burden of this disease, the scientific community is still struggling to find an effective means of prevention. The contribution of genetics to the development of atopy cannot be altered, but environmental changes as well as pharmacotherapy have been studied as modifiable risk factors. Many trials to date have been effective only for subjects with certain characteristics. This is likely because asthma is a heterogenous condition, with a variety of triggers and clinical phenotypes. Thus far, a universally effective prevention strategy has eluded us. However, if an intervention can be found to prevent asthma and the allergic march, it will greatly improve quality of life for millions of sufferers and decrease healthcare expenditures.

Is There Benefit in Identifying Asthma Triggers During an Exacerbation?

Introduction. Allergen-specific IgE (sIgE) testing provides an objective assessment of sensitization to an allergen. Goal. To identify the time when serum measurements of sIgE would be most sensitive. Methods. This was a prospective study conducted between September 1, 2015, and February 25, 2019. Subjects ≥5 and ≤18 years of age, seen in the ED or admitted with an asthma exacerbation, were tested for total IgE and 8 perennial sIgE levels. Subjects with elevated sIgE were tested again after symptom resolution. Results. A total of 104 subjects were enrolled; 50 subjects were eligible for inclusion in the analysis. There were statistically significant differences between the visits for all sIgE, except Alternaria alternatum. Conclusions. In pediatric patients, serum sIgE levels measured during an asthma exacerbation were elevated compared with when their asthma was in better control. sIgE testing during an asthma exacerbation may help identify asthma triggers, mitigate exposure, and hence improve asthma control.

Respiratory pathogens and clinical outcomes in children with an asthma exacerbation: A systematic review

BACKGROUND

In asthmatic children, respiratory pathogens are identified in 60%-80% of asthma exacerbations, contributing to a significant burden of illness. The role of pathogens in the clinical evolution of exacerbations is unknown.

OBJECTIVE

We systematically reviewed the association between the presence of pathogens and clinical outcomes in children with an asthma exacerbation.

METHOD

PubMed, EMBASE, BIOSIS, and the Cochrane Central Register of Controlled Trials were searched up to October 2016 for studies reporting on respiratory pathogen exposure and clinical outcome. The Risk of Bias in Non-Randomized Studies of Interventions tool was used for quality assessment.

RESULTS

Twenty-eight observational studies (N = 4,224 children) reported on 112 different associations between exposure to any pathogen (n = 45), human rhinovirus (HRV; n = 34), atypical bacteria (n = 21), specific virus (n = 11), or bacteria (n = 1) and outcomes of exacerbation severity (n = 26), health care use (n = 38), treatment response (n = 19), and morbidity (n = 29). Restricting the analysis only to comparisons with a low to moderate risk of bias, we observed an association between HRV and higher exacerbation severity on presentation (regression p = .016) and between the presence of any pathogen and emergency department treatment failure (odds ratio [OR] = 1.57; 95% CI 1.04% to 2.37%). High-quality evidence for effect on morbidity or health care use is lacking.

CONCLUSIONS

Further research on the role of pathogen-treatment interaction and outcomes is required to inform the need for point-of-care, real-time testing for pathogens. Studies with a sufficiently large sample size that address selection bias, correctly adjust for confounding, and rigorously report core patient-centred outcomes are necessary to improve knowledge.

Beyond Respiratory Syncytial Virus and Rhinovirus in the Pathogenesis and Exacerbation of Asthma: The Role of Metapneumovirus, Bocavirus and Influenza Virus

Respiratory viruses other than rhinovirus or respiratory syncytial virus, including human metapneumovirus, influenza virus, and human bocavirus, are important pathogens in acute wheezing illness and asthma exacerbations in young children. Whether infection with these viruses in early life is associated with recurrent wheezing and/or asthma is not fully investigated, although there are data to suggest children with human metapneumovirus lower respiratory tract infection may have a higher likelihood of subsequent and recurrent wheezing several years after initial infection.

Mast cells as protectors of health

Mast cells (MCs), which are well known for their effector functions in T_H2-skewed allergic and also autoimmune inflammation, have become increasingly acknowledged for their role in protection of health. It is now clear that they are also key modulators of immune responses at interface organs, such as the skin or gut. MCs can prime tissues for adequate inflammatory responses and cooperate with dendritic cells in T-cell activation. They also regulate harmful immune responses in trauma and help to successfully orchestrate pregnancy. This review focuses on the beneficial effects of MCs on tissue homeostasis and elimination of toxins or venoms. MCs can enhance pathogen clearance in many bacterial, viral, and parasitic infections, such as through Toll-like receptor 2-triggered degranulation, secretion of antimicrobial cathelicidins, neutrophil recruitment, or provision of extracellular DNA traps. The role of MCs in tumors is more ambiguous; however, encouraging new findings show they can change the tumor microenvironment toward antitumor immunity when adequately triggered. Uterine tissue remodeling by α-chymase (mast cell protease [MCP] 5) is crucial for successful embryo implantation. MCP-4 and the tryptase MCP-6 emerge to be protective in central nervous system trauma by reducing inflammatory damage and excessive scar formation, thereby protecting axon growth. Last but not least, proteases, such as carboxypeptidase A, released by FcεRI-activated MCs detoxify an increasing number of venoms and endogenous toxins. A better understanding of the plasticity of MCs will help improve these advantageous effects and hint at ways to cut down detrimental MC actions.

Allergen Exposure in Lymphopenic Fas-Deficient Mice Results in Persistent Eosinophilia Due to Defects in Resolution of Inflammation

Asthma is characterized by chronic airway type-2 inflammation and eosinophilia, yet the mechanisms involved in chronic, non-resolving inflammation remain poorly defined. Previously, our group has found that when Rag-deficient mice were reconstituted with Fas-deficient B6 LPR T cells and sensitized and challenged, the mice developed a prolonged type-2-mediated airway inflammation that continued for more than 6 weeks after the last antigen exposure. Surprisingly, no defect in resolution was found when intact B6 LPR mice or T cell specific Fas-conditional knockout mice were sensitized and challenged. We hypothesize that the homeostatic proliferation induced by adoptive transfer of T cells into Rag-deficient mice may be an important mechanism involved in the lack of resolution. To investigate the role of homeostatic proliferation, we induced lymphopenia in the T cell-specific Fas-conditional knockout mice by non-lethal irradiation and sensitized them when T cells began to repopulate. Interestingly, we found that defective Fas signaling on T cells plus antigen exposure during homeostatic proliferation was sufficient to induce prolonged eosinophilic airway inflammation. In conclusion, our data show that the combination of transient lymphopenia, abnormal Fas-signaling, and antigen exposure leads to the development of a prolonged airway eosinophilic inflammatory phase in our mouse model of experimental asthma.

Biologics in pediatric lung disease

PURPOSE OF REVIEW

Although biologic therapies can provide outstanding efficacy in the management of lung disease, especially asthma, most of these agents have been approved only for adults. Recent findings provide new strategies for using these agents in children.

RECENT FINDINGS

Extensive evidence has consistently demonstrated the efficacy and safety of biologic therapy for asthma. In addition, some studies have documented potentially important secondary effects, such as improving response to respiratory virus infection in asthmatic patients. Additional strategies for improving asthma control using biologic therapy, such as seasonal administration, have been suggested, and may limit cost while still providing a high degree of efficacy.

SUMMARY

Many of the current biologics are able to readily establish control even in asthmatic patients for whom inhaled steroid and long-acting β agonist have failed. However, biologics currently have limited regulatory approval and availability in the pediatric age range, despite this age being disproportionately affected by asthma. In addition, successful biologics for asthma to date have largely been limited to the Th2-high endotype of asthma, and there is great need for similar medications to target the Th2-low endotype. Other pediatric lung disease might well benefit from the specificity allowed by biologic therapy.

Fluid Balance Is Associated with Clinical Outcomes and Extravascular Lung Water in Children with Acute Asthma Exacerbation

RATIONALE

The effects of fluid administration during acute asthma exacerbation are likely unique in this patient population: highly negative inspiratory intrapleural pressure resulting from increased airway resistance may interact with excess fluid administration to favor the accumulation of extravascular lung water, leading to worse clinical outcomes.

OBJECTIVES

Investigate how fluid balance influences clinical outcomes in children hospitalized for asthma exacerbation.

METHODS

We analyzed the association between fluid overload and clinical outcomes in a retrospective cohort of children admitted to an urban children's hospital with acute asthma exacerbation. These findings were validated in two cohorts: a matched retrospective and a prospective observational cohort. Finally, ultrasound imaging was used to identify extravascular lung water and investigate the physiological basis for the inferential findings.

MEASUREMENTS AND MAIN RESULTS

In the retrospective cohort, peak fluid overload [(fluid input - output)/weight] is associated with longer hospital length of stay, longer treatment duration, and increased risk of supplemental oxygen use (P values < 0.001). Similar results were obtained in the validation cohorts. There was a strong interaction between fluid balance and intrapleural pressure: the combination of positive fluid balance and highly negative inspiratory intrapleural pressures is associated with signs of increased extravascular lung water (P < 0.001), longer length of stay (P = 0.01), longer treatment duration (P = 0.03), and increased risk of supplemental oxygen use (P = 0.02).

CONCLUSIONS

Excess volume administration leading to fluid overload in children with acute asthma exacerbation is associated with increased extravascular lung water and worse clinical outcomes.

The pediatric asthma yardstick: Practical recommendations for a sustained step-up in asthma therapy for children with inadequately controlled asthma

Current asthma guidelines recommend a control-based approach to management involving assessment of impairment and risk followed by implementation of treatment strategies individualized according to the patient's needs and preferences. However, for children with asthma, achieving control can be elusive. Although tools are available to help children (and families) track and manage day-to-day symptoms, when and how to implement a longer-term step-up in care is less clear. Furthermore, treatment is challenged by the 3 age groups of childhood-adolescence (12-18 years old), school age (6-11 years old), and young children (≤5 years old)-and what works for 1 age group might not be the best approach for another. The Pediatric Asthma Yardstick provides an in-depth assessment of when and how to step-up therapy for the child with not well or poorly controlled asthma. Development of this tool follows others in the Yardstick series, presenting patient profiles and step-up strategies based on current guidance documents, but modified according to newer data and the authors' combined clinical experience. The objective is to provide clinicians who treat children with asthma practical and clinically relevant recommendations for each step-up and each intervention, with the intent of helping practitioners better treat their pediatric patients with asthma, particularly those who do not always respond to recommended therapies.

Pediatric Asthma Management in China: Current and Future Challenges

The purpose of this report was to review the state of asthma diagnosis and treatment in China and to examine challenges in achieving earlier diagnosis and treatment. The prevalence of asthma in children in China has increased over past decades, and data published in 2013 indicated a prevalence of 3.0% in children aged 0-14 years. Although this prevalence has increased, the percentage of children with acute asthma attacks decreased from 86% in 2000 to 77% in 2010, and the frequency of hospitalizations for asthma attacks decreased from 54.0 to 47%. These decreases are attributed to aggressive promotion of the Global Initiative for Asthma (GINA) protocol and updated Chinese guidelines for the prevention and treatment of asthma in children. The use of inhaled corticosteroids increased and that of systemic corticosteroids decreased between 2000 and 2010. Despite these advances, a number of issues remain to be addressed. Parents lack basic knowledge of asthma and fear the use of corticosteroids. Physician education regarding the diagnosis of asthma in children aged < 6 years is lacking. Patients require training in the administration of inhaled corticosteroids and control of environmental triggers. The Chinese national guidelines for childhood asthma have been updated, but implementation remains a real challenge.

Respiratory viral infections and atopic development: From possible mechanisms to advances in treatment

Atopic sensitization and allergic diseases are increasing in modernized countries. These diseases affect millions of individuals, but the mechanisms behind their development are not fully understood. One hypothesis relates to early life respiratory viral infections driving the development of atopic disease including asthma. This review presents the current state of the field, focusing on epidemiologic data supporting a role for early life respiratory viruses in the development of specific IgE, both against aeroallergens and the respiratory virus. Our own work using the Sendai mouse model is then summarized to provide a potential mechanistic explanation for how a respiratory viral infection could drive development of atopic sensitization and disease. We then discuss the components of this mechanistic pathway that have and have not been validated in humans. Finally, we discuss areas ripe for research, as well as potential and current therapeutics that might disrupt the link between respiratory viral infections in early life and atopic sensitization/disease.

Baseline serum CXCL10 and IL-12 levels may predict severe asthmatics' responsiveness to omalizumab

BACKGROUND

Omalizumab, a humanized anti-IgE monoclonal antibody, is the first molecularly targeted drug for severe asthmatics. However, responses to omalizumab vary widely among patients.

OBJECTIVES

This study aimed to assess the potential of baseline serum cytokine levels as predictors of responsiveness to omalizumab.

METHODS

Thirty-one patients with severe, persistent asthma were enrolled in this study and administered omalizumab for at least 1 year. Response to omalizumab was assessed based on the physician's global evaluation of treatment effectiveness (GETE) at 48 weeks of treatment. Blood samples were collected at baseline and 16 and 32 weeks after starting omalizumab and measured for 30 cytokines by Luminex 200 and ELISA. Exhaled nitric oxide (FeNO) levels, peripheral blood eosinophil counts, pre-bronchodilator pulmonary functions and Asthma Quality of Life Questionnaire scores were determined at baseline and 16, 32 and 48 weeks after starting omalizumab. The numbers of clinically significant asthma exacerbations in the previous year and during 48 weeks of treatment with omalizumab were assessed.

RESULTS

GETE assessment showed 19 responders (61.3%) and 12 non-responders (38.7%). Responders showed significantly higher levels of CXCL10 and IL-12 at baseline compared to non-responders (CXCL10: responders, 1530.0 ± 315.2 pg/ml vs. non-responders, 1066.0 ± 396.8 pg/ml, P = 0.001; IL-12: responders, 60.2 ± 39.2 pg/ml vs. non-responders, 32.2 ± 26.3 pg/ml, P = 0.04). ROC curves to distinguish responders from non-responders using the baseline serum CXCL10 level showed a good AUC of 0.83. At 32 weeks of omalizumab therapy, serum CXCL10 tended to be increased (1350 ± 412.3 pg/ml at baseline vs. 1529 ± 637.6 pg/ml at 32 weeks, P = 0.16) and serum IL-12 tended to be decreased (49.4 ± 37.0 pg/ml at baseline vs. 43.9 ± 30.9 pg/ml at 32 weeks, P = 0.05). On the other hand, serum IL-5 and PDGF were significantly decreased (IL-5: 54.2 ± 13.8 pg/ml at baseline vs. 49.1 ± 12.5 pg/ml at 32 weeks, P = 0.008; PDGF: 4821 ± 2458 pg/ml at baseline vs. 4219 ± 1951 pg/ml at 32 weeks, P = 0.048).

CONCLUSIONS

High baseline serum CXCL10 and IL-12 levels may be useful in predicting a good omalizumab response in severe asthmatics.

Effects of Omalizumab on Rhinovirus Infections, Illnesses, and Exacerbations of Asthma

RATIONALE

Allergic inflammation has been linked to increased susceptibility to viral illnesses, but it is unclear whether this association is causal.

OBJECTIVES

To test whether omalizumab treatment to reduce IgE would shorten the frequency and duration of rhinovirus (RV) illnesses in children with allergic asthma.

METHODS

In the PROSE (Preventative Omalizumab or Step-up Therapy for Severe Fall Exacerbations) study, we examined children with allergic asthma (aged 6-17 yr; n = 478) from low-income census tracts in eight U.S. cities, and we analyzed virology for the groups randomized to treatment with guidelines-based asthma care (n = 89) or add-on omalizumab (n = 259). Weekly nasal mucus samples were analyzed for RVs, and respiratory symptoms and asthma exacerbations were recorded over a 90-day period during the fall seasons of 2012 or 2013. Adjusted illness rates (illnesses per sample) by treatment arm were calculated using Poisson regression.

MEASUREMENTS AND MAIN RESULTS

RVs were detected in 97 (57%) of 171 exacerbation samples and 2,150 (36%) of 5,959 nonexacerbation samples (OR, 2.32; P < 0.001). Exacerbations were significantly associated with detection of rhinovirus C (OR, 2.85; P < 0.001) and rhinovirus A (OR, 2.92; P < 0.001), as well as, to a lesser extent, rhinovirus B (OR, 1.98; P = 0.019). Omalizumab decreased the duration of RV infection (11.2 d vs. 12.4 d; P = 0.03) and reduced peak RV shedding by 0.4 log units (95% confidence interval, -0.77 to -0.02; P = 0.04). Finally, omalizumab decreased the frequency of RV illnesses (risk ratio, 0.64; 95% confidence interval, 0.49-0.84).

CONCLUSIONS

In children with allergic asthma, treatment with omalizumab decreased the duration of RV infections, viral shedding, and the risk of RV illnesses. These findings provide direct evidence that blocking IgE decreases susceptibility to RV infections and illness. Clinical trial registered with www.clinicaltrials.gov (NCT01430403).

Role of viral infections in the development and exacerbation of asthma in children

Viral infections are closely linked to wheezing illnesses in children of all ages. Respiratory syncytial virus (RSV) is the main causative agent of bronchiolitis, whereas rhinovirus (RV) is most commonly detected in wheezing children thereafter. Severe respiratory illness induced by either of these viruses is associated with subsequent development of asthma, and the risk is greatest for young children who wheeze with RV infections. Whether viral illnesses actually cause asthma is the subject of intense debate. RSV-induced wheezing illnesses during infancy influence respiratory health for years. There is definitive evidence that RSV-induced bronchiolitis can damage the airways to promote airway obstruction and recurrent wheezing. RV likely causes less structural damage and yet is a significant contributor to wheezing illnesses in young children and in the context of asthma. For both viruses, interactions between viral virulence factors, personal risk factors (eg, genetics), and environmental exposures (eg, airway microbiome) promote more severe wheezing illnesses and the risk for progression to asthma. In addition, allergy and asthma are major risk factors for more frequent and severe RV-related illnesses. Treatments that inhibit inflammation have efficacy for RV-induced wheezing, whereas the anti-RSV mAb palivizumab decreases the risk of severe RSV-induced illness and subsequent recurrent wheeze. Developing a greater understanding of personal and environmental factors that promote more severe viral illnesses might lead to new strategies for the prevention of viral wheezing illnesses and perhaps reduce the subsequent risk for asthma.

Immune mechanisms of respiratory viral infections in asthma

The more severe pathology respiratory viral infections produce in asthma sufferers is a result of a dysregulated immune response. Excess type 2 inflammation is a well-described feature of virally induced asthma exacerbations, with growing evidence that production of antiviral interferons may also be impaired. However, the mechanisms underlying these are little understood. This review summarizes the current understanding and recent discoveries of the cellular and molecular events that follow viral infections in asthma. In particular, we discuss differences in viral sensing and intracellular signalling pathways upstream of interferon induction in asthma, and the role of epithelial-derived cytokines in orchestrating type 2 immunopathology, including type 2 innate lymhpoid cells (ILC2s).

Effects of Allergic Sensitization on Antiviral Immunity: Allergen, Virus, and Host Cell Mechanisms

PURPOSE OF REVIEW

Multiple clinical and epidemiological studies demonstrate links between allergic sensitization and virus-induced atopic disease exacerbations. This review summarizes the recent findings regarding allergen, viral, and host cellular mechanisms relevant to these observations.

RECENT FINDINGS

Recent studies have focused on the molecular pathways and genetic influences involved in allergen-mediated inhibition of innate antiviral immune responses. Multiple tissue and cell types from atopic individuals across the atopy spectrum exhibit deficient interferon responses to a variety of virus infections. Impairment in barrier function, viral RNA and DNA recognition by intracellular sensing molecules, and dysregulation of signaling components are broadly affected by allergic sensitization. Finally, genetic predisposition by numerous nucleotide polymorphisms also impacts immune pathways and potentially contributes to virus-associated atopic disease pathogenesis. Allergen-virus interactions in the setting of atopy involve complex tissue and cellular mechanisms. Future studies defining the pathways underlying these interactions could uncover potential therapeutic targets. Available data suggest that therapies tailored to restore specific components of antiviral responses will likely lead to improved clinical outcomes in allergic disease.

Immune Responses in Rhinovirus-Induced Asthma Exacerbations

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

Advances in asthma in 2016: Designing individualized approaches to management

In this year's Advances in Asthma review, we discuss viral infections in asthmatic patients and potential therapeutic agents, the microbiome, novel genetic associations with asthma, air quality and climate effects on asthma, exposures during development and long-term sequelae of childhood asthma, patient-centered outcomes research, and precision medicine. In addition, we discuss application of biomarkers to precision medicine and new information on asthma medications. New evidence indicates that rhinovirus-triggered asthma exacerbations become more severe as the degree of sensitization to dust mite and mouse increase. The 2 biggest drivers of asthma severity are an allergy pathway starting with allergic sensitization and an environmental tobacco smoke pathway. In addition, allergic sensitization and blood eosinophils can be used to select medications for management of early asthma in young children. These current findings, among others covered in this review, represent significant steps toward addressing rapidly advancing areas of knowledge that have implications for asthma management.

New Insights into Cockroach Allergens

PURPOSE OF REVIEW

This review addresses the most recent developments on cockroach allergen research in relation to allergic diseases, especially asthma.

RECENT FINDINGS

The number of allergens relevant to cockroach allergy has recently expanded considerably up to 12 groups. New X-ray crystal structures of allergens from groups 1, 2, and 5 revealed interesting features with implications for allergen standardization, sensitization, diagnosis, and therapy. Cockroach allergy is strongly associated with asthma particularly among children and young adults living in inner-city environments, posing challenges for disease control. Environmental interventions targeted at reducing cockroach allergen exposure have provided conflicting results. Immunotherapy may be a way to modify the natural history of cockroach allergy and decrease symptoms and asthma severity among sensitized and exposed individuals. The new information on cockroach allergens is important for the assessment of allergen markers of exposure and disease, and for the design of immunotherapy trials.