House dust mite sensitization in toddlers predicts current wheeze at age 12 years

Efficacy and safety of sublingual immunotherapy using house dust mite tablet for 1-4 years old children with perennial allergic rhinitis

BACKGROUND

Sublingual immunotherapy (SLIT) for perennial allergic rhinitis (AR) has not been extensively studied in preschoolers. We investigated the efficacy and safety of house dust mite (HDM) SLIT-tablet for children aged 1-4 years.

METHODS

Children aged 1-4 years with AR were divided into SLIT (n = 22) and control (n = 12) groups based on their guardians' preferences. The SLIT group received a daily dose of 10,000 JAU of HDM SLIT-tablet for 12 months, whereas the control group received symptomatic treatment only.

RESULTS

The baseline median age was 41 and 34 months in the SLIT and control groups, respectively, and the median AR symptom score was 4 for both groups. Compared with baseline, the AR symptom score had decreased significantly in the SLIT group after 12 months (score: 3, p = .002), whereas it tended to increase in the control group (score: 6, p = .08). Adverse reactions to SLIT were mild and occurred in eight patients (36%). In the SLIT group, Dermatophagoides (D.) farinae-specific IgE (sIgE) levels increased during the first 6 months and decreased to baseline levels at 12 months. In the control group, D. farinae-sIgE levels had increased significantly at 12 months compared to baseline (p = .01). D. farinae-specific IgG4 and HDM IgE-blocking factor levels were significantly increased at 12 months compared to baseline in the SLIT group only (p < .001). A lower wheezing frequency was seen in the SLIT group (0.3%) compared to the control group (0.7%).

CONCLUSION

This pilot study demonstrated the efficacy, safety, and immunomodulatory effects of HDM SLIT-tablet in preschoolers with AR.

Do early-life allergic sensitization and respiratory infection interact to increase asthma risk?

OBJECTIVE

The 'two-hit' hypothesis theorizes that early life allergic sensitization and respiratory infection interact to increase asthma risk.

METHODS

We sought to determine in a high allergy risk birth cohort whether interactions between early life allergic sensitization and respiratory infection were associated with increased risk for asthma at ages 6-7 years and 18 years. Allergic sensitization was assessed at 6, 12, and 24 months by skin prick testing to 3 food and 3 aeroallergens. Respiratory infection was defined as reported "cough, rattle, or wheeze" and assessed 4-weekly for 15 months, at 18 months, and age 2 years. Regression analysis was undertaken with parent-reported asthma at age 6-7 years and doctor diagnosed asthma at 18 years as distinct outcomes. Interactions between allergic sensitization and respiratory infection were explored with adjustment made for potential confounders.

RESULTS

Odds of asthma were higher in sensitized compared to nonsensitized children at age 6-7 years (OR = 14.46; 95% CI 3.99-52.4), There was no evidence for interactions between allergic sensitization and early life respiratory infection, with a greater frequency of respiratory infection up to 2 years of age associated with increased odds for asthma at age 6-7 years in both sensitized (OR = 1.13; 95% CI 1.02-1.25, n = 199) and nonsensitized children (OR = 1.31; 1.11-1.53, n = 211) (p interaction = 0.089). At age 18 years, these associations were weaker.

CONCLUSIONS

Our findings do not support 'two-hit' interactions between early life allergic sensitization and respiratory infection on asthma risk. Both early life respiratory infections and allergic sensitization were risk factors and children with either should be monitored closely for development of asthma.

House dust mite SCIT reduces asthma risk and significantly improves long-term rhinitis and asthma control-A RWE study

BACKGROUND

The German Therapy Allergen Ordinance (TAO) triggered an ongoing upheaval in the market for house dust mite (HDM) allergen immunotherapy (AIT) products. Three HDM subcutaneous AIT (SCIT) products hold approval in Germany and therefore will be available after the scheduled completion of the TAO procedure in 2026. In general, data from clinical trials on the long-term effectiveness of HDM AIT are rare. We evaluated real-world data (RWD) in a retrospective, observational cohort study based on a longitudinal claims database including 60% of all German statutory healthcare prescriptions to show the long-term effectiveness of one of these products in daily life. Aim of this analysis was to provide a per product analysis on effectiveness of mite AIT as it is demanded by international guidelines on AIT.

METHODS

Subjects between 5 and 70 years receiving their first (index) prescription of SCIT with a native HDM product (SCIT group) between 2009 and 2013 were included. The exactly 3:1 matched control group received prescriptions for only symptomatic AR medication (non-AIT group); the evaluation period for up to 6 years of follow-up ended in February 2017. Study endpoints were the progression of allergic rhinitis (AR) and asthma, asthma occurrence and time to the onset of asthma after at least 2 treatment years.

RESULTS

In total, 892 subjects (608 adults and 284 children/adolescents) were included in the SCIT group and 2676 subjects (1824 adults and 852 children/adolescents) in the non-AIT group. During the follow-up period after at least 2 years of SCIT, the number of prescriptions in the SCIT group was reduced by 62.8% (p < .0001) for AR medication and by 42.4% for asthma medication (p = .0003). New-onset asthma risk was significantly reduced in the SCIT vs non-AIT group by 27.0% (p = .0212). The asthma-preventive effect of SCIT occurred 15 months after start of the treatment. In the SCIT group, the time to onset of asthma was prolonged compared to the non-AIT group (p = .0010).

CONCLUSION

In this first product based RWD analysis on SCIT with a native HDM product, patients aged 5 to 70 years benefited from AIT in the long term in terms of reduced progression of AR and asthma after at least 2 years of treatment. The effects seemed to last for up to 6 years after treatment termination. A significantly reduced risk of asthma onset was observed, starting after 15 months of treatment.

Future Directions of Allergen Immunotherapy for Allergic Rhinitis: Experts' Perspective

Allergen immunotherapy (AIT) is broadly used all over the world as the only available disease-modifying treatment option. The aim of this experts' perspective is to address 7 important unmet needs for the further direction of AIT and to provide the readership with the authors' positions on these topics. An international group of experts in the field of AIT have formulated 7 important aspects for the future position of AIT, performed a current literature review, and proposed a consented position on these topics. The aspects discussed and consented by the authors include: (1) alternative routes of allergen application in AIT, (2) potential of recombinant vaccines, (3) the role of allergy diagnosis based on component-resolved diagnosis for AIT composition, (4) the impact of COVID-19 vaccination for further innovations in AIT, (5) potential of combining biologics to AIT, (6) future innovations in high-risk children/adolescents, and (7) the future regulatory position on AIT. Important unmet needs and topics for AIT have been addressed in this expert review. The authors' views and personal position on these 7 aspects have also been elaborated.

Early Atopic Sensitization to House-Dust Mite in Children with Recurrent Wheeze-A Cross-Sectional Study

OBJECTIVES

To determine sensitization to house-dust mite (HDM) antigen in under-five children with recurrent wheeze, compare it with nonwheezers, and assess atopic comorbidities in them.

METHODS

A cross-sectional study was done in the Pediatric department of a teaching hospital in North India, in 190 children aged 1-5 y. Out of these, 127 had recurrent wheeze (RW), and 63 had no wheeze (NW). Sensitivity was done by skin prick test (SPT) for two dust mites antigens: Dermatophagoide farinae and Dermatophagoide pteronyssinus antigens. In addition, atopic comorbidities like atopic dermatitis and allergic rhinitis were assessed.

RESULTS

Mean age of the study population was 34.52 ± 20.50 mo. SPT positivity for either of the dust mites was 97 (76.4%) in RW and 13 (20.6%) in NW which was significant (p < 0.001, aOR = 12.27). HDM species sensitization for D. pteronyssinus was 55.1% vs. 15.9% (p < 0.001 aOR = 7.81) and D. farinae was 39.4% vs. 9.5% (p < 0.001, aOR = 5.45) in groups, respectively. Mean wheal size in RW Group was also significantly higher than NW group for D. pteronyssinus (2.39 ± 1.44 vs. 0.52 ± 1.19 mm, median (IQR) 3 (1-3), p < 0.001), D. farinae (1.80 ± 1.39 vs. 0.32 ± 1.00 mm, median (IQR) 2 (0-3), p < 0.001). Allergic rhinitis was present in 55 (43.3%) vs. 7 (11.1%) (p < 0.001), atopic dermatitis in 28 (22%) vs. 2 (3.2%) (p = 0.001) in group 1 and 2, respectively. All children with allergic rhinitis had HDM sensitization in both groups.

CONCLUSION

This study showed early sensitization to HDM in children with recurrent wheeze. Atopic comorbidities were also present in them.

Frequent IgE recognition of Blomia tropicalis allergen molecules in asthmatic children and young adults in equatorial Africa

Background

Asthma is not well investigated in equatorial Africa and little is known about the disease-associated allergen molecules recognized by IgE from patients in this area. The aim was to study the molecular IgE sensitization profile of asthmatic children and young adults in a semi-rural area (Lambaréné) of an equatorial African country (Gabon), to identify the most important allergen molecules associated with allergic asthma in equatorial Africa.

Methods

Fifty-nine asthmatic patients, mainly children and few young adults, were studied by skin prick testing to Dermatophagoides pteronyssinus (Der p), D. farinae (Der f), cat, dog, cockroach, grass, Alternaria and peanut. Sera were obtained from a subset of 35 patients, 32 with positive and 3 with negative skin reaction to Der p and tested for IgE reactivity to 176 allergen molecules from different allergen sources by ImmunoCAP ISAC microarray technology and to seven recombinant Blomia tropicalis (Blo t) allergens by IgE dot blot assay.

Results

Thirty-three of the 59 patients (56%) were sensitized to Der p and 23 of them (39%) were also sensitized to other allergen sources, whereas 9 patients (15%) were only sensitized to allergen sources other than Der p. IgE serology analyses (n=35) showed high IgE-binding frequencies to the Blo t allergens Blo t 5 (43%), Blo t 21 (43%) and Blo t 2 (40%), whereas the Der p allergens rDer p 2, rDer p 21 and rDer p 5 (34%, 29% and 26%) were less frequently recognized. Only few patients showed IgE reactivity to allergens from other allergen sources, except to allergens containing carbohydrate determinants (CCDs) or to wasp venom allergens (i.e., antigen 5).

Conclusion

Our results thus demonstrate that IgE sensitization to mite allergens is very prevalent in asthmatics in Equatorial Africa with B. tropicalis allergen molecules representing the most important ones associated with allergic asthma.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Understanding the development of Th2 cell-driven allergic airway disease in early life

Allergic diseases, including atopic dermatitis, allergic rhinitis, asthma, and food allergy, are caused by abnormal responses to relatively harmless foreign proteins called allergens found in pollen, fungal spores, house dust mites (HDM), animal dander, or certain foods. In particular, the activation of allergen-specific helper T cells towards a type 2 (Th2) phenotype during the first encounters with the allergen, also known as the sensitization phase, is the leading cause of the subsequent development of allergic disease. Infants and children are especially prone to developing Th2 cell responses after initial contact with allergens. But in addition, the rates of allergic sensitization and the development of allergic diseases among children are increasing in the industrialized world and have been associated with living in urban settings. Particularly for respiratory allergies, greater susceptibility to developing allergic Th2 cell responses has been shown in children living in urban environments containing low levels of microbial contaminants, principally bacterial endotoxins [lipopolysaccharide (LPS)], in the causative aeroallergens. This review highlights the current understanding of the factors that balance Th2 cell immunity to environmental allergens, with a particular focus on the determinants that program conventional dendritic cells (cDCs) toward or away from a Th2 stimulatory function. In this context, it discusses transcription factor-guided functional specialization of type-2 cDCs (cDC2s) and how the integration of signals derived from the environment drives this process. In addition, it analyzes observational and mechanistic studies supporting an essential role for innate sensing of microbial-derived products contained in aeroallergens in modulating allergic Th2 cell immune responses. Finally, this review examines whether hyporesponsiveness to microbial stimulation, particularly to LPS, is a risk factor for the induction of Th2 cell responses and allergic sensitization during infancy and early childhood and the potential factors that may affect early-age response to LPS and other environmental microbial components.

Biomarkers associated with the development of comorbidities in patients with atopic dermatitis: A systematic review

Biomarkers associated with the development of comorbidities in atopic dermatitis (AD) patients have been reported, but have not yet been systematically reviewed. Seven electronic databases were searched, from database inception to September 2021. English language randomized controlled trials, prospective and retrospective cohort, and case-control studies that investigated the association between a biomarker and the development of comorbidities in AD patients were included. Two authors independently screened the records for eligibility, one extracted all data, and critically appraised the quality of studies and risk of bias. Fifty six articles met the inclusion criteria, evaluating 146 candidate biomarkers. The most frequently reported biomarkers were filaggrin mutations and allergen specific-IgE. Promising biomarkers include specific-IgE and/or skin prick tests predicting the development of asthma, and genetic polymorphisms predicting the occurrence of eczema herpeticum. The identified studies and biomarkers were highly heterogeneous, and associated with predominately moderate-to-high risk of bias across multiple domains. Overall, findings were inconsistent. High-quality studies assessing biomarkers associated with the development of comorbidities in people with AD are lacking. Harmonized datasets and independent validation studies are urgently needed.

Maturation and specialization of group 2 innate lymphoid cells through the lung-gut axis

Innate lymphoid cells (ILC) are abundant in mucosal tissues. They serve critical functions in anti-pathogen response and tissue homeostasis. However, the heterogenous composition of ILCs in mucosal sites and their various maturation trajectories are less well known. In this study, we characterize ILC types and functions from both the lung and the small intestine, and identify their tissue-specific markers. We find that ILC2s residing in the lung express CCR2, whereas intestinal ILC2s express CCR4. Through the use of CCR2 and CCR4 reporter mice, we show that ILC2s undergo translocation via the lung-gut axis upon IL-33 treatment. This trajectory of ILC2s is also observed at the postnatal stage. Allergen-induced activation of lung ILC2s affects the homeostasis of gut ILC2s. Together, our findings implicate that ILCs display tissue-specific features in both the lung and gut, and ILC2s mature along the lung-gut axis in particular homeostatic and inflammatory conditions.

Bioaerosol and microbial exposures from residential evaporative coolers and their potential health outcomes: A review

Evaporative cooling is an energy efficient form of air conditioning in dry climates that functions by pulling hot, dry outdoor air across a wet evaporative pad. While evaporative coolers can help save energy, they also have the potential to influence human health. Studies have shown residential evaporative coolers may pull outdoor air pollutants into the home or contribute to elevated levels of indoor bioaerosols that may be harmful to health. There is also evidence that evaporative coolers can enable a diverse microbial environment that may confer early-life immunological protection against the development of allergies and asthma or exacerbate these same hypersensitivities. This review summarizes the current knowledge of bioaerosol and microbiological studies associated with evaporative coolers, focusing on harmful and potentially helpful outcomes from their use. We evaluate the effects of evaporative coolers on indoor bacterial endotoxins, fungal β-(1 → 3)-D-glucans, dust mite antigens, residential microbial communities, and Legionella pneumophila. To our knowledge, this is the first review to summarize and evaluate studies on the influence that evaporative coolers have on the bioaerosol and microbiological profile of homes. This brings to light a gap in the literature on evaporative coolers, which is the lack of data on health effects associated with their use.

Impaired skin barrier and allergic sensitization in early infancy

BACKGROUND

Factors predicting allergic sensitization in the first 6 months of life are poorly understood. We aimed to determine whether eczema, dry skin, and high transepidermal water loss (TEWL) at 3 months were associated with allergic sensitization at 6 months of age and, secondarily, to establish whether these characteristics predicted sensitization from 3 to 6 months of age.

METHODS

At 3 months of age, 1,994 infants from the population-based PreventADALL birth cohort in Norway and Sweden were assessed for eczema and dry skin on the cheeks and/or extensors; impaired skin barrier function, defined as TEWL in the upper quartile (>9.4 g/m² /h), and allergen-specific IgE levels <0.1 kU_A /L, available in 830. At 6 months, we assessed allergic sensitization to any food (egg, cow's milk, peanut, wheat, soy) or inhalant (birch, timothy grass, dog, and cat) allergen by a skin prick test wheal diameter ≥2 mm larger than negative control.

RESULTS

Any sensitization was found in 198 of the 1,994 infants (9.9%), the majority to food allergens (n = 177, 8.9%). Eczema, dry skin, and high TEWL at 3 months increased the risk of sensitization at 6 months; adjusted odds ratios 4.20 (95% CI 2.93-6.04), 2.09 (95% CI 1.51-2.90) and 3.67 (95% CI 2.58-5.22), respectively. Eczema predicted sensitization with 55.6% sensitivity and 68.1% specificity; dry skin with 65.3% sensitivity and 57.3% specificity; and high TEWL with 61.7% sensitivity and 78.1% specificity.

CONCLUSION

Eczema, dry skin, and high TEWL at 3 months predicted allergic sensitization at 6 months of age.

Allergen Management in Children with Type 2-High Asthma

Children exposed to various indoor and outdoor allergens are placed at an increased risk of developing asthma in later life, with sensitization in these individuals being a strong predictor of disease morbidity. In addition, aeroallergen exposure influences asthma outcomes through an interplay with adverse determinants of health. The goal of this review is to provide an introductory overview of factors related to aeroallergen exposure in type 2-high childhood asthma. These include the relevance of exposure in asthma exacerbations and severity, and the evidence-base for avoidance and treatment for sensitization to these allergens. This review will focus on both indoor aeroallergens (house dust mite, pet, cockroach, mold, and rodent) and outdoor aeroallergens (pollens and molds). Treatment of aeroallergen sensitization in children with asthma includes avoidance and removal measures, although there is limited evidence of clinical benefit especially with single-strategy approaches. We will also address the interplay of aeroallergens and climate change, adverse social determinants, and the current COVID-19 pandemic, when we have seen a dramatic reduction in asthma exacerbations and emergency department visits among children. While there are many factors that are hypothesized to contribute to this reduction, among them is a reduced exposure to outdoor seasonal aeroallergens.

Asthma management in low- and middle-income countries: case for change

Asthma is the most common non-communicable disease in children, and among the most common in adults. The great majority of people with asthma live in low- and middle-income countries (LMICs), where they suffer disproportionately high asthma-related morbidity and mortality. Essential inhaled medications, particularly those containing inhaled corticosteroids (ICS), are often unavailable or unaffordable, and this explains much of the global burden of preventable asthma morbidity and mortality.Guidelines developed for LMICs are generally based on the outdated assumption that patients with asthma symptoms <1-3 times/week do not need (or benefit from) ICS. Even when ICS is prescribed, many patients manage their asthma with oral or inhaled short-acting beta₂ agonist (SABA) alone, due to issues of availability and affordability. A single ICS-formoterol inhaler-based approach to asthma management for all severities of asthma, from mild to severe, starting at diagnosis, might overcome SABA overuse/over-reliance and reduce the burden of symptoms and severe exacerbations. However, ICS-formoterol inhalers are currently very poorly available or unaffordable in LMICs. There is a pressing need for pragmatic clinical trial evidence of the feasibility and cost-effectiveness of this and other strategies to improve asthma care in these countries.The global health inequality in asthma care that deprives so many children, adolescents and adults of healthy lives and puts them at increased risk of death - despite the availability of highly effective therapeutic approaches - is unacceptable. A World Health Assembly Resolution on universal access to affordable effective asthma care is needed to focus attention and investment on addressing this need.

Allergic diseases in infancy: I - Epidemiology and current interpretation

Objective

Among non-communicable diseases, the prevalence of allergic diseases has increased significantly in the new millennium. The increase of allergic diseases is linked to the changing environment of infants.

Methods

This narrative review summarizes the discussions and conclusions from the 8^th Human Milk Workshop. Information from the fields of pediatrics, epidemiology, biology, microbiology, and immunology are summarized to establish a framework describing potential avenues for the prevention of allergic diseases in the future.

Results

Several environmental circumstances are linked to the development of allergic diseases. While cesarean section is increasing the risk of allergies, early childhood exposure to a farm environment has a protective effect. From their analysis, nutritive and non-nutritive factors influencing the allergy risk in later life have been identified. The effect of breastfeeding on food allergy development is non-univocal. Human milk components including immunoglobulins, cytokines, and prebiotics have been indicated as important for allergy prevention.

Conclusion

Many factors linked to the western lifestyle have been associated with the development of allergic diseases. This suggests several theories that may serve as a basis for new protective interventions. While it is indubitable that mother's milk protects from infectious diseases, its role in the prevention of allergic diseases is to be elucidated.

Immunologic Strategies for Prevention of Asthma

A new understanding of factors leading to the development of asthma has pointed to potential primary, secondary, and tertiary prevention strategies. Some, such as genetic makeup, are not yet modifiable. Interventions targeting other factors such as maternal intake of vitamin D or environmental control can be used to decrease the risk of asthma development (primary prevention). The benefits of a diversified microbiome could be considered when recommending allergen avoidance and pet ownership. In addition to reducing symptoms, allergen immunotherapy is also worth considering for prevention of new sensitivities (secondary prevention) in addition to the development of asthma. Ongoing studies involving the use of bacterial vaccines and biologics may provide additional strategies for primary prevention of asthma and for reducing symptoms once it has developed (tertiary prevention). As the relative benefits of these strategies are defined, they should have an increasingly important place in the prevention and management of asthma.

Group 2 Innate Lymphoid Cells: Team Players in Regulating Asthma

Type 2 immunity helps protect the host from infection, but it also plays key roles in tissue homeostasis, metabolism, and repair. Unfortunately, inappropriate type 2 immune reactions may lead to allergy and asthma. Group 2 innate lymphoid cells (ILC2s) in the lungs respond rapidly to local environmental cues, such as the release of epithelium-derived type 2 initiator cytokines/alarmins, producing type 2 effector cytokines such as IL-4, IL-5, and IL-13 in response to tissue damage and infection. ILC2s are associated with the severity of allergic asthma, and experimental models of lung inflammation have shown how they act as playmakers, receiving signals variously from stromal and immune cells as well as the nervous system and then distributing cytokine cues to elicit type 2 immune effector functions and potentiate CD4⁺ T helper cell activation, both of which characterize the pathology of allergic asthma. Recent breakthroughs identifying stromal- and neuronal-derived microenvironmental cues that regulate ILC2s, along with studies recognizing the potential plasticity of ILC2s, have improved our understanding of the immunoregulation of asthma and opened new avenues for drug discovery.

Comparison of Liquefied Petroleum Gas Cookstoves and Wood Cooking Fires on PM2.5 Trends in Brick Workers' Homes in Nepal

Prior studies document a high prevalence of respiratory symptoms among brick workers in Nepal, which may be partially caused by non-occupational exposure to fine particulate matter (PM2.5) from cooking. In this study, we compared PM2.5 levels and 24 h trends in brick workers' homes that used wood or liquefied petroleum gas (LPG) cooking fuel. PM2.5 filter-based and real-time nephelometer data were collected for approximately 24 h in homes and outdoors. PM2.5 was significantly associated with fuel type and location (p < 0.0001). Pairwise comparisons found significant differences between gas, indoor (geometric mean (GM): 79.32 μg/m3), and wood, indoor (GM: 541.14 μg/m3; p = 0.0002), and between wood, indoor, and outdoor (GM: 48.38 μg/m3; p = 0.0006) but not between gas, indoor, and outdoor (p = 0.56). For wood fuel homes, exposure peaks coincided with mealtimes. For LPG fuel homes, indoor levels may be explained by infiltration of ambient air pollution. In both wood and LPG fuel homes, PM2.5 levels exceeded the 24 h limit (25.0 µg/m3) proposed by the World Health Organization. Our findings suggest that increasing the adoption of LPG cookstoves and decreasing ambient air pollution in the Kathmandu valley will significantly lower daily PM2.5 exposures of brick workers and their families.

Real-world evidence of subcutaneous allergoid immunotherapy in house dust mite-induced allergic rhinitis and asthma

BACKGROUND

The objective of this study was to analyze the effectiveness of allergen immunotherapy (AIT) with an allergoid in the treatment of house dust mites (HDM)-induced allergic rhinitis and/or asthma based on recent real-life data. The outcomes were measured using asthma incidence and consumption of corresponding medications as the indicator of persisting symptoms.

METHODS

In this retrospective cohort analysis of a German longitudinal prescription database, patients who received at least two relevant mite AIT prescriptions in two different successive seasonal cycles were compared with non-AIT patients who received at least three symptomatic allergic rhinitis (AR) prescriptions in successive mite seasons. Study endpoints included AR progression, asthma progression, asthma occurrence, and therapy adherence. We used multivariate regression analyses to estimate the effects of AIT, adjusting for relevant variables.

RESULTS

This study included 2350 patients receiving a mite allergoid and 64 740 control patients. After up to 6 years of follow-up, patients treated with mite allergoid required significantly fewer AR and asthma prescriptions (59.7% vs 10.8%) than the control group, and the probability of asthma development was significantly lower. The adherence of patients receiving allergoid was 63.8% at the end of the second year and 38.6% at the end of the third year.

CONCLUSIONS

This real-world evidence confirms the good efficacy of subcutaneous AIT with HDM mite allergoid in the treatment of allergic rhinitis and/or asthma. Up to 6 years of follow-up revealed significant effects in allergic rhinitis by measuring the number of AR medications and demonstrating significant reductions in asthma medications.

Allergen Immunotherapy in Pediatric Asthma: A Pragmatic Point of View

To date, the only disease-modifying treatment strategy for allergic rhinitis and asthma is allergen immunotherapy (AIT). There is evidence that AIT improves allergic rhinitis and asthma, such as reducing symptom severity and medication use and improving of quality of life, with a long-lasting effect after the end of the course. The recent clinical trials evidenced AIT effectiveness and safety in allergic asthma. Consequently, the current version of the GINA (Global Initiative for Asthma) guidelines recommend AIT as an add-on therapy for asthma. There is also evidence that AIT may exert preventive activity on the possible progression from allergic rhinitis to asthma in children and the onset of new sensitizations. The present review provides a pragmatic summary of the clinical indications of AIT in pediatric asthma, including the immunological mechanisms, the predictive biomarkers, and the safety issues in clinical practice.

Group 2 Innate Lymphoid Cells and the House Dust Mite-Induced Asthma Mouse Model

Asthma is an important issue not only in health but also in economics worldwide. Therefore, asthma animal models have been frequently used to understand the pathogenesis of asthma. Recently, in addition to acquired immunity, innate immunity has also been thought to be involved in asthma. Among innate immune cells, group 2 innate lymphoid cells (ILC2s) have been considered to be crucial for eosinophilic airway inflammation by releasing T helper 2 cytokines. Moreover, house dust mites (HDMs) belonging to group 1 act on airway epithelial cells not only as allergens but also as cysteine proteases. The production of interleukin-25 (IL-25), IL-33, and thymic stromal lymphopoietin (TSLP) from airway epithelial cells was induced by the protease activity of HDMs. These cytokines activate ILC2s, and activated ILC2s produce IL-5, IL-9, IL-13, and amphiregulin. Hence, the HDM-induced asthma mouse model greatly contributes to understanding asthma pathogenesis. In this review, we highlight the relationship between ILC2s and the HDM in the asthma mouse model to help researchers and clinicians not only choose a proper asthma mouse model but also to understand the molecular mechanisms underlying HDM-induced asthma.

EAACI Allergen Immunotherapy User's Guide

Allergen immunotherapy is a cornerstone in the treatment of allergic children. The clinical efficiency relies on a well-defined immunologic mechanism promoting regulatory T cells and downplaying the immune response induced by allergens. Clinical indications have been well documented for respiratory allergy in the presence of rhinitis and/or allergic asthma, to pollens and dust mites. Patients who have had an anaphylactic reaction to hymenoptera venom are also good candidates for allergen immunotherapy. Administration of allergen is currently mostly either by subcutaneous injections or by sublingual administration. Both methods have been extensively studied and have pros and cons. Specifically in children, the choice of the method of administration according to the patient's profile is important. Although allergen immunotherapy is widely used, there is a need for improvement. More particularly, biomarkers for prediction of the success of the treatments are needed. The strength and efficiency of the immune response may also be boosted by the use of better adjuvants. Finally, novel formulations might be more efficient and might improve the patient's adherence to the treatment. This user's guide reviews current knowledge and aims to provide clinical guidance to healthcare professionals taking care of children undergoing allergen immunotherapy.

The Role of Dust Mites in Allergy

House dust mites are an unsurpassed cause of atopic sensitization and allergic illness throughout the world. The major allergenic dust mites Dermatophagoides pteronyssinus, Dermatophagoides farinae, Euroglyphus maynei, and Blomia tropicalis are eight-legged members of the Arachnid class. Their approximately 3-month lifespan comprises egg, larval, protonymph, tritonymph, and adult stages, with adults, about one fourth to one third of a millimeter in size, being at the threshold of visibility. The geographic and seasonal distributions of dust mites are determined by their need for adequate humidity, while their distribution within substrates is further determined by their avoidance of light. By contacting the epithelium of the eyes, nose, lower airways, skin, and gut, the allergen-containing particles of dust mites can induce sensitization and atopic symptoms in those organs. Various mite allergens, contained primarily in mite fecal particles but also in shed mite exoskeletons and decaying mite body fragments, have properties that include proteolytic activity, homology with the lipopolysaccharide-binding component of Toll-like receptor 4, homology with other invertebrate tropomyosins, and chitin-cleaving and chitin-binding activity. Mite proteases have direct epithelial effects including the breaching of tight junctions and the stimulation of protease-activated receptors, the latter inducing pruritus, epithelial dysfunction, and cytokine release. Other components, including chitin, unmethylated mite and bacterial DNA, and endotoxin, activate pattern recognition receptors of the innate immune system and act as adjuvants promoting sensitization to mite and other allergens. Clinical conditions resulting from mite sensitization and exposure include rhinitis, sinusitis, conjunctivitis, asthma, and atopic dermatitis. Systemic allergy symptoms can also occur from the ingestion of cross-reacting invertebrates, such as shrimp or snail, or from the accidental ingestion of mite-contaminated foods. Beyond their direct importance as a major allergen source, an understanding of dust mites leads to insights into the nature of atopy and of allergic sensitization in general.

The Role of Early Life Food Sensitization in Adolescent Lung Function: Results from 2 Birth Cohort Studies

BACKGROUND

It is unclear whether early life food sensitization (as opposed to aeroallergen sensitization) is associated with subsequent poor lung function.

OBJECTIVES

We investigated the associations between food sensitization in the first 2 years of life and lung function at 12 to 18 years and whether these observed associations are mediated through aeroallergen sensitization or asthma.

METHODS

We used data from a high-risk cohort (Melbourne Atopy Cohort Study [MACS]) and a population-based "Influence of life-style-related factors on the development of the Immune System and Allergies in East and West Germany plus the influence of traffic emissions and genetics" (LISAplus) cohort. Food sensitization was assessed at 6, 12, and 24 months in MACS and 24 months in LISAplus. Lung function was evaluated by spirometry at 12 and 18 years in MACS and 15 years in LISAplus. Linear regression models were used to estimate the association with sensitization (food and/or aeroallergen) while adjusting for potential confounders.

RESULTS

Sensitization to food without aeroallergen at 6 months was associated with reduced forced expiratory volume in 1 second (FEV₁) at both 12 years (-153 mL; 95% confidence interval [CI] = -256 mL, -51 mL) and 18 years (-206 mL; 95% CI = -347 mL, -65 mL) in MACS. Similar results were observed for sensitization measured at 12 months but not at 24 months. Early-life asthma (but not aeroallergen sensitization) partially mediated these associations. Both cohorts showed that only aeroallergen sensitization at 24 months but not food sensitization was associated with lower adolescent lung function.

CONCLUSIONS

This study showed that food sensitization at 6 and 12 months was associated with reduced FEV₁ in adolescence. Our finding that this link is not completely mediated by either subsequent asthma or aeroallergen sensitization is novel and suggests that early food sensitization itself can be used to identify high-risk groups for poor lung health.

Impaired Tumor-Necrosis-Factor-α-driven Dendritic Cell Activation Limits Lipopolysaccharide-Induced Protection from Allergic Inflammation in Infants

Infants have a higher risk of developing allergic asthma than adults. However, the underlying mechanism remains unknown. We show here that sensitization of mice with house-dust mites (HDMs) in the presence of low-dose lipopolysaccharide (LPS) prevented T helper 2 (Th2) cell allergic responses in adult, but not infant, mice. Mechanistically, adult CD11b⁺ migratory dendritic cells (mDCs) upregulated the transcription factor T-bet in response to tumor necrosis factor-α (TNF-α), which was rapidly induced after HDM + LPS sensitization. Consequently, adult CD11b⁺ mDCs produced interleukin-12 (IL-12), which prevented Th2 cell development by promoting T-bet upregulation in responding T cells. Conversely, infants failed to induce TNF-α after HDM + LPS sensitization. Therefore, CD11b⁺ mDCs failed to upregulate T-bet and did not secrete IL-12 and Th2 cell responses normally developed in infant mice. Thus, the availability of TNF-α dictates the ability of CD11b⁺ mDCs to suppress allergic Th2-cell responses upon dose-dependent endotoxin sensitization and is a key mediator governing susceptibility to allergic airway inflammation in infant mice.

Epidemiology of Asthma in Children and Adults

Asthma is a globally significant non-communicable disease with major public health consequences for both children and adults, including high morbidity, and mortality in severe cases. We have summarized the evidence on asthma trends, environmental determinants, and long-term impacts while comparing these epidemiological features across childhood asthma and adult asthma. While asthma incidence and prevalence are higher in children, morbidity, and mortality are higher in adults. Childhood asthma is more common in boys while adult asthma is more common in women, and the reversal of this sex difference in prevalence occurs around puberty suggesting sex hormones may play a role in the etiology of asthma. The global epidemic of asthma that has been observed in both children and adults is still continuing, especially in low to middle income countries, although it has subsided in some developed countries. As a heterogeneous disease, distinct asthma phenotypes, and endotypes need to be adequately characterized to develop more accurate and meaningful definitions for use in research and clinical settings. This may be facilitated by new clustering techniques such as latent class analysis, and computational phenotyping methods are being developed to retrieve information from electronic health records using natural language processing (NLP) algorithms to assist in the early diagnosis of asthma. While some important environmental determinants that trigger asthma are well-established, more work is needed to define the role of environmental exposures in the development of asthma in both children and adults. There is increasing evidence that investigation into possible gene-by-environment and environment-by-environment interactions may help to better uncover the determinants of asthma. Therefore, there is an urgent need to further investigate the interrelationship between environmental and genetic determinants to identify high risk groups and key modifiable exposures. For children, asthma may impair airway development and reduce maximally attained lung function, and these lung function deficits may persist into adulthood without additional progressive loss. Adult asthma may accelerate lung function decline and increase the risk of fixed airflow obstruction, with the effect of early onset asthma being greater than late onset asthma. Therefore, in managing asthma, our focus going forward should be firmly on improving not only short-term symptoms, but also the long-term respiratory and other health outcomes.

Efficacy and safety of SQ house dust mite sublingual immunotherapy-tablet in Japanese children

BACKGROUND

The SQ house dust mite (HDM) sublingual immunotherapy (SLIT)-tablet (TO-203, Torii, Japan/ALK, Denmark) treatment has been effective against respiratory allergic diseases in patients aged ≥12 years during European, Japanese, and North American trials. This trial was conducted to investigate the efficacy and safety of this treatment in Japanese children (5-17 years) with moderate-to-severe HDM allergic rhinitis (AR).

METHODS

In this randomized, double-blind, placebo-controlled trial, 458 Japanese children were randomly assigned to a daily SQ HDM SLIT-tablet [10 000 Japanese Allergy Unit (JAU), equivalent to 6 SQ-HDM in Europe and the US] or placebo (1:1) treatment for 1 year. Inclusion required an AR symptom score of ≥7 on at least 7 days during a 14-day run-in period while symptomatic treatment was withdrawn. The primary endpoint was the total combined rhinitis score (TCRS) comprising AR symptom and medication scores during the last 8 weeks of the treatment period.

RESULTS

The analysis of primary endpoint demonstrated statistically significant absolute reduction in TCRS of 1.22 with a relative difference of 23% (95% confidence interval, 14% to 31%) in the 10 000 JAU compared with placebo. Predefined stratified analyses revealed the same degree of efficacy of 1.11 (P = 0.002), 21% (8% to 32%) and 1.36 (P = 0.001), 26% (11% to 38%), respectively, in pediatric (5-11 years) and adolescent subjects (12-17 years). The treatment was well tolerated by both pediatric and adolescent subjects.

CONCLUSION

This trial, for the first time, demonstrated the efficacy and safety of the HDM SLIT-tablet in pediatric patients with moderate-to-severe HDM AR (JapicCTI-152953).

SLIT's Prevention of the Allergic March

PURPOSE OF REVIEW

The progression of atopic disorders from atopic dermatitis in infants to allergic rhinitis and asthma in children, adolescents, and adults defines the allergy march. Allergen immunotherapy is the only causal treatment altering the immunological mechanism underlying the allergic diseases. The sublingual administration route is more acceptable than the subcutaneous one in pediatric age.

RECENT FINDINGS

Several studies show the efficacy and safety profile of sublingual immunotherapy (SLIT) for the treatment of respiratory allergy diseases, but few data are available on its effect of primary and secondary prevention of allergic disease. The purpose of this manuscript is to review the latest studies addressing the effect of SLIT on the development of new sensitizations in not sensitized or already sensitized patients and progression of the allergy march.

Indoor Environmental Interventions and their Effect on Asthma Outcomes

PURPOSE OF REVIEW

The use of environmental interventions to improve outcomes in asthmatics has long been an elusive goal. While numerous interventions have been studied, the results of clinical trials have been mixed. This review aims to identify combinations of interventions that have been proven to be effective and to propose a model for using them in a clinical setting.

RECENT FINDINGS

An NIH workshop emphasized a need for research to identify effective interventions for reducing indoor exposures and improving asthma outcomes. A number of innovative measures were described, though evidence supporting their use was lacking. A recent systematic review described various interventions for which evidence is available. The greatest challenge for this approach is the same as that for the medical approach to treatment: nonadherence. Given evidence for effective interventions, control of environmental exposures should lead to improved asthma outcomes. Methods to improve adherence need to be identified.

Prevalence of house dust mite allergens in low-income homes with evaporative coolers in a semiarid climate

House dust mites are typically absent in homes in arid and semiarid climates due to low humidity. Evaporative "swamp" cooling significantly increases indoor humidity in dry climates and is suspected of promoting dust mite survival in these regions. We investigated the prevalence and concentration of mite allergens in dust from low-income homes (N = 22) with evaporative coolers in Utah County, Utah. Overall, 15 homes (68.2%) were positive for either Der p 1 or Der f 1 in at least 1 location. Geometric mean allergen levels in mattresses were 0.107 and 0.087 ug/g dust for Der p 1 and Der f 1, respectively. In furniture, levels were 0.143 and 0.165 ug/g dust for Der p1 and Der f 1, respectively. The percentage of positive homes in this study was much higher than previously reported in larger homes with swamp coolers in the same community. These results suggest socioeconomic factors may play a role in dust mite allergen prevalence in homes with evaporative coolers in dry climates.

Immunotherapy and Asthma in Children

Allergen immunotherapy (AIT) is still the only disease-modifying treatment strategy for IgE-mediated allergic diseases, with consolidated evidence both in adults and children. AIT is effective in determining clinical improvement of allergic rhinitis and asthma, such as reduced symptoms, medication use, and improvement of quality of life, with a long-lasting effect after cessation of treatment. Results from recent clinical studies have implemented the evidence of effectiveness and safety of allergen immunotherapy for the treatment of allergic asthma, so that the current asthma guidelines now recommend sublingual immunotherapy as an add-on therapy for asthma in adults and adolescents with house dust mite allergy, allergic rhinitis, and exacerbations despite low-to-moderate dose ICS, with forced expiratory volume in 1 second more than 70% predicted. AIT may also reduce the risk of progression from allergic rhinitis to asthma in children and prevent the onset of new sensitizations, thus representing a potentially preventive method of treatment. The aim of this review is to present an updated overview of the clinical indications of AIT, with particular reference to pediatric asthma, of the mechanisms of clinical and immunological tolerance to allergens, and of the potential biomarkers predicting clinical response.

Early-life sensitization to hen's egg predicts asthma and rhinoconjunctivitis at 14 years of age

BACKGROUND

Sensitization to both inhalant and food allergens has been shown to be risk factors for development of asthma and rhinoconjunctivitis (RC). However, few studies have addressed the role of transient or persistent IgE sensitization to specific allergens in early life for later development of allergic diseases. The aim of this study was to explore the association between transient and persistent sensitization in early life and the development of asthma and RC at 6 and 14 years.

METHODS

The Danish Allergy Research Center (DARC) cohort is a prospective non-interventional birth cohort study comprising 562 children. For the purpose of this study, we examined a subgroup of the original cohort with specific IgE measured at, at least 3 of 4 follow-ups between 3 and 18 months of age (n = 366). Multiple logistic regression models were used to investigate the association between transient and persistent early-life sensitization to groups of and to individual allergens and asthma and RC at 6 and 14 years compared to a reference group with no sensitization.

RESULTS

Both transient early-life sensitization and persistent early-life sensitization to cow's milk or hen's egg proteins were associated with asthma (aOR 3.99[1.41-11.32] and 5.95[1.78-19.92]) and RC (aOR 2.94[1.19-7.28] and 6.18[1.86-20.53]) at 14 years, this association being driven mainly by sensitization to hen's egg. Transient early-life sensitization to house dust mite (HDM) had increased risk of asthma (aOR 3.80[1.17-12.41]) at 14 years.

CONCLUSIONS

Early transient IgE sensitization and persistent IgE sensitization to hen's egg were associated with asthma and RC at 14 years. Furthermore, sensitization to HDM was associated with asthma at 14 years.

Sensitization to dust mite defines different phenotypes of asthma: A multicenter study

BACKGROUND

Indoor allergens are risk factors for asthma: Thus, the characterization of indoor air quality is important for studying environment-health relationships in children. In particular, Dermatophagoides pteronyssinus is the dominant allergen for asthma. We cross-sectionally investigated the relationships among respiratory symptoms and function, airway inflammation, allergen sensitization, and indoor allergen concentration.

METHODS

One hundred and thirty-two children aging 10-14 years and living in a Southern Mediterranean area were evaluated by parental questionnaires. Spirometry, exhaled nitric oxide (FeNO), skin prick tests, total, and specific serum IgE analyses were performed along with the evaluation of home dust samples for the content in Der p 1 allergen. Three clusters were created on the basis of the presence/absence of wheeze in the last 12 months (Wh12m) and Der p 1-specific IgE level.

RESULTS

Cluster 1 (Wh12m+/high Der p 1 IgE) presented higher FeNO and poorer pulmonary function (lower FEV₁ and FEF_25%-75% ), while its symptom score was not different from Cluster 2 (Wh12m+/low Der p 1 IgE). Cluster 3 (Wh12m-/low IgE) showed the lowest FeNO values and pulmonary function similar to Cluster 2. Within Cluster 1, both Der p 1-specific IgE and FeNO were positively correlated with dust Der p 1.

CONCLUSIONS

Similar asthma phenotypes may occur in children despite differences in their atopic state. In atopic children, sensitizing allergens in the indoor environment may increase airway inflammation worsening pulmonary function. Moreover, environmental exposures may contribute to the development of asthma-like symptoms also in the absence of atopic sensitization, thus contributing to asthma overdiagnosis.

Grandmaternal smoking increases asthma risk in grandchildren: A nationwide Swedish cohort

BACKGROUND

There is growing interest in exposures prior to conception as possible risk factors for offspring asthma. Although partially supported by evidence from limited human studies, current evidence is inconsistent and based on recall of exposure status.

OBJECTIVE

We aimed to investigate grandmaternal smoking during pregnancy and the risk of asthma in grandchildren using prospectively collected population-based data.

METHODS

Information on grandmaternal and maternal smoking during pregnancy and grandchild use of asthma medications was collected from national Swedish registries. Associations between grandmaternal smoking during pregnancy (10-12 weeks) and asthma medication use in grandchildren were investigated using generalized estimating equations. Ages at which asthma medications were prescribed classified childhood asthma into never, early transient (0-3 years), late onset (3-6 years) and early persistent (0-3 and 3-6 years) phenotypes.

RESULTS

From 1982 to 1986, 44 583 grandmothers gave birth to 46 197 mothers, who gave birth to 66 271 grandchildren (born 1996-2010). Children aged 1-6 years had an increased asthma risk if their grandmothers had smoked during pregnancy, with a higher risk for more exposure (10+ cigs/d; adjusted OR 1.23; 1.17, 1.30). Maternal smoking did not modify this relationship.

CONCLUSIONS & CLINICAL RELEVANCE

Children had an increased risk of asthma in the first 6 years of life if their grandmothers smoked during early pregnancy, independent of maternal smoking. Importantly, this exhibited a dose-response relationship and was associated with a persistent childhood asthma phenotype. These findings support possible epigenetic transmission of risk from environmental exposures in previous generations.

Current and future management of the young child with early onset wheezing

PURPOSE OF REVIEW

In this review, we discuss current thinking in relation to available guidelines for the care of preschool-aged children with recurrent wheezing, while highlighting the gaps in our knowledge and discussing changes that could occur over the next 5 years.

RECENT FINDINGS

The Asthma Predictive Index as well as allergen-specific IgE, peripheral eosinophil count and exhaled nitric oxide are perhaps underutilized sources of information that can assist in predicting progression to asthma and response to therapies. Inhaled corticosteroids and leukotriene receptor antagonists decrease impairment and exacerbation frequency in wheezing children but are not disease modifying. Macrolides may be useful during acute wheezing episodes for preventing progression to more severe symptoms. Monoclonal antibodies targeting IgE and TH2 cytokines have been successful in trials of adults and older children with asthma, but trials in younger children are needed.

SUMMARY

Establishing the phenotype and endotype of young wheezing children can be useful for prognostication of future asthma risk as well as for selection of the most appropriate treatment. Primary asthma prevention strategies are needed during the critical developmental window in early life prior to the onset of irrecoverable loss of lung function.

Environmental determinants of allergy and asthma in early life

Allergic disease prevalence has increased significantly in recent decades. Primary prevention efforts are being guided by study of the exposome (or collective environmental exposures beginning during the prenatal period) to identify modifiable factors that affect allergic disease risk. In this review we explore the evidence supporting a relationship between key components of the external exposome in the prenatal and early-life periods and their effect on atopy development focused on microbial, allergen, and air pollution exposures. The abundance and diversity of microbial exposures during the first months and years of life have been linked with risk of allergic sensitization and disease. Indoor environmental allergen exposure during early life can also affect disease development, depending on the allergen type, dose, and timing of exposure. Recent evidence supports the role of ambient air pollution in allergic disease inception. The lack of clarity in the literature surrounding the relationship between environment and atopy reflects the complex interplay between cumulative environmental factors and genetic susceptibility, such that no one factor dictates disease development in all subjects. Understanding the effect of the summation of environmental exposures throughout a child's development is needed to identify cost-effective interventions that reduce atopy risk in children.

Comparison of the roles of house dust mite allergens, ovalbumin and lipopolysaccharides in the sensitization of mice to establish a model of severe neutrophilic asthma

Neutrophilic asthma (NA) is associated with a severe disease course and poor response to corticosteroids. The present study aimed to compare the effects of various concentrations of house dust mite (HDM) allergens, ovalbumin (OVA), the major egg allergen, and lipopolysaccharide (LPS) in combination on the onset of severe NA. Female C57BL/6 mice were grouped according to a random number table and intranasally sensitized with HDM/LPS/OVA extracts on days 0, 1 and 2 of the study. In group 1, mice received 50 µg HDM + 50 µg OVA + 15 µg LPS, mice in group 2 received 50 µg HDM + 100 µg OVA + 15 µg LPS, mice in group 3 received 100 µg HDM + 50 µg OVA + 15 µg LPS and those in group 4 received 100 µg HDM + 100 µg OVA + 15 µg LPS, while mice in the control group received saline only. The mice were then challenged by OVA solution with atomized excitation on days 14, 15, 18, 19 and 20 for 30 min each. Ethology, airway hyperresponsiveness (AHR), immune cell distributions in bronchoalveolar lavage fluid (BALF), and specific cytokines interleukin 17A (IL-17A) and IL-4 in serum were assessed. Histological examination of inflammation by hematoxylin and eosin staining and immunohistochemical assessment of neutrophils (NEU), eosinophils (EOS), IL-17A and IL-4 were also performed. Compared with the control group, the HDM/OVA/LPS-sensitized groups 1-4 had markedly increased BALF cells, serum interleukin IL-17A and IL-4, inflammatory cell infiltration, EOS as well as IL-17A and IL-4 by immunohistochemical staining (all P<0.05). Among the four HDM/OVA/LPS-sensitized groups, mice of group 4 had higher AHR, a significantly higher total cell number, NEU and EOS in BALF as well as significantly higher NEU and NEU/EOS ratios according to immunohistochemical staining when compared to groups 1-3 (P<0.05 for all). In conclusion, sensitization with 100 µg HDM + 100 µg OVA + 15 µg LPS successfully established a severe asthma model with a predominantly neutrophilic inflammatory phenotype.

Age at onset and persistence of eczema are related to subsequent risk of asthma and hay fever from birth to 18 years of age

BACKGROUND

Few studies have simultaneously addressed the importance of age of onset and persistence of eczema for the subsequent development of asthma and hay fever, particularly into early adulthood.

METHODS

A high-risk birth cohort was recruited comprising 620 infants, who were then followed up frequently until 2 years of age, annually from age 3 to 7, then at 12 and 18 years, to document any episodes of eczema, current asthma, and hay fever. The generalized estimation equation technique was used to examine asthma and hay fever outcomes at 6 (n = 325), 12 (n = 248) and 18 (n = 240) years, when there was consistency of associations across the follow-ups.

RESULTS

Very early-onset persistent (onset <6 months, still present from 2 to 5 years) eczema was related to current asthma (adjusted OR = 3.2 [95% CI = 1.7-6.1]), as was very early-onset remitting eczema (onset <6 months but not present from 2-5 years, OR = 2.7, 95% CI = 1.0-7.2) and early-onset persistent eczema (onset from 6-24 months, OR = 2.3, 95% CI = 1.2-4.7). Late-onset eczema (commenced from 2-5 years) was associated with increased risk of asthma at 12 years (OR = 3.0, 95% CI=1.1-8.2) but not at age 6 years. Only very early-onset persistent eczema was associated with increased risk of hay fever (aOR = 2.4, 95% CI = 1.4-4.1).

CONCLUSION AND CLINICAL RELEVANCE

Eczema which commences in early infancy and persists into toddler years is strongly associated with asthma, and to a lesser extent hay fever, in high-risk children. If these associations are causal, prevention of early-life eczema might reduce the risk of respiratory allergy.

International consensus (ICON) on: clinical consequences of mite hypersensitivity, a global problem

Since mite allergens are the most relevant inducers of allergic diseases worldwide, resulting in significant morbidity and increased burden on health services, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), formed by the American Academy of Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), the European Academy of Allergy and Clinical Immunology (EAACI), and the World Allergy Organization (WAO), has proposed to issue an International Consensus (ICON) on the clinical consequences of mite hypersensitivity. The objectives of this document are to highlight aspects of mite biology that are clinically relevant, to update the current knowledge on mite allergens, routes of sensitization, the genetics of IgE responses to mites, the epidemiologic aspects of mite hypersensitivity, the clinical pictures induced by mites, the diagnosis, specific immunotherapeutic approaches, and prevention.

The Influence of the Microbiome on Early-Life Severe Viral Lower Respiratory Infections and Asthma-Food for Thought?

Severe viral lower respiratory infections are a major cause of infant morbidity. In developing countries, respiratory syncytial virus (RSV)-bronchiolitis induces significant mortality, whereas in developed nations the disease represents a major risk factor for subsequent asthma. Susceptibility to severe RSV-bronchiolitis is governed by gene-environmental interactions that affect the host response to RSV infection. Emerging evidence suggests that the excessive inflammatory response and ensuing immunopathology, typically as a consequence of insufficient immunoregulation, leads to long-term changes in immune cells and structural cells that render the host susceptible to subsequent environmental incursions. Thus, the initial host response to RSV may represent a tipping point in the balance between long-term respiratory health or chronic disease (e.g., asthma). The composition and diversity of the microbiota, which in humans stabilizes in the first year of life, critically affects the development and function of the immune system. Hence, perturbations to the maternal and/or infant microbiota are likely to have a profound impact on the host response to RSV and susceptibility to childhood asthma. Here, we review recent insights describing the effects of the microbiota on immune system homeostasis and respiratory disease and discuss the environmental factors that promote microbial dysbiosis in infancy. Ultimately, this knowledge will be harnessed for the prevention and treatment of severe viral bronchiolitis as a strategy to prevent the onset and development of asthma.

Is there a march from early food sensitization to later childhood allergic airway disease? Results from two prospective birth cohort studies

BACKGROUND

The march from early aeroallergen sensitization to subsequent respiratory allergy is well established, but it is unclear whether early life food sensitization precedes and further increases risk of allergic airway disease.

OBJECTIVE

To assess the association between food sensitization in the first 2 years of life and subsequent asthma and allergic rhinitis by age 10-12 years.

METHODS

We used data from two independent cohorts: the high-risk Melbourne Atopic Cohort Study (MACS) (n = 620) and the population-based LISAplus (n = 3094). Food sensitization was assessed at 6, 12, and 24 months in MACS and 24 months in LISAplus. Multiple logistic regressions were used to estimate associations between sensitization to food only, aeroallergen only, or both and allergic airway disease.

RESULTS

When compared to non-sensitized children, sensitization to food only at 12 months in MACS and 24 months in LISAplus was associated with increased risk of current asthma (aOR = 2.2; 95% CI 1.1, 4.6 in MACS and aOR = 4.9; 2.4, 10.1 in LISAplus). Similar results were seen for allergic rhinitis. Additionally, cosensitization to food and aeroallergen in both cohorts at any tested point was a stronger predictor of asthma (at 24 months, aOR = 8.3; 3.7, 18.8 in MACS and aOR = 14.4; 5.0, 41.6 in LISAplus) and allergic rhinitis (at 24 months, aOR = 3.9; 1.9, 8.1 in MACS and aOR = 7.6; 3.0, 19.6 in LISAplus).

CONCLUSIONS

In both cohorts, food sensitization (with or without aeroallergen sensitization) in the first two years of life increased the risk of subsequent asthma and allergic rhinitis. These findings support the role of early life food sensitization in the atopic march and suggest trials to prevent early onset have the potential to reduce the development of allergic airways disease.

Allergy in severe asthma

It is well recognized that atopic sensitization is an important risk factor for asthma, both in adults and in children. However, the role of allergy in severe asthma is still under debate. The term 'Severe Asthma' encompasses a highly heterogeneous group of patients who require treatment on steps 4-5 of GINA guidelines to prevent their asthma from becoming 'uncontrolled', or whose disease remains 'uncontrolled' despite this therapy. Epidemiological studies on emergency room visits and hospital admissions for asthma suggest the important role of allergy in asthma exacerbations. In addition, allergic asthma in childhood is often associated with severe asthma in adulthood. A strong association exists between asthma exacerbations and respiratory viral infections, and interaction between viruses and allergy further increases the risk of asthma exacerbations. Furthermore, fungal allergy has been shown to play an important role in severe asthma. Other contributing factors include smoking, pollution and work-related exposures. The 'Allergy and Asthma Severity' EAACI Task Force examined the current evidence and produced this position document on the role of allergy in severe asthma.

The Role of Sensitization to Allergen in Asthma Prediction and Prevention

The burden of asthma in childhood is considerable worldwide, although some populations are much more affected than others. Many attempts have been made by different investigators to identify the factors that could predict asthma development or persistence in childhood. In this review, the relation between atopic sensitization as an indicator of allergy and asthma in childhood will be discussed. Cross sectional studies, carried out in different countries, failed to show any firm correlation between asthma and atopic sensitization. Birth cohort mainly of infants at high risk for asthma and case-control studies showed that atopic sensitization was a risk factor for current asthma in children older than 6 years. In general, clear relations are observed mostly in affluent Western countries, whereas in less affluent countries, the picture is more heterogeneous. For the prediction of asthma development or persistence in school age children, other prerequisites should also be fulfilled such as family history of asthma and wheezing episodes at preschool age. Despite the conductance of different studies regarding the potential role of allergen avoidance for the primary prevention of childhood asthma, it does not seem that this approach is of benefit for primary prevention purposes. However, the identification of children at risk for asthma is of benefit as these subjects could be provided with the best management practices and with the appropriate secondary prevention measures.

Identification of infants and preschool children at risk for asthma: predictive scores and biomarkers

PURPOSE OF REVIEW

Predictive asthma scores and biomarkers are important tools that help many physicians in the identification of infants and preschool children at high risk for asthma. Our objective was to review recent data regarding this subject.

RECENT FINDINGS

Recently, two new predictive asthma scores were developed with some innovative features, such as the definition of scales of asthma risk. In a systematic review, 12 asthma-predictive models were identified with heterogeneous performance. Prospective studies have shown that elevated fractional concentration of nitric oxide (FeNO) is a strong risk factor for latter asthma among early wheezers, and a predictive asthma score with FeNO values has been proposed. Plasma cytokines and exhaled volatile organic compounds were also identified as potential asthma predictors.

SUMMARY

Predictive scores are simple, practical, and inexpensive tools to identify children at high risk for asthma at school age. Whereas some scores are better at identifying asthmatic children, others are better at excluding the diagnosis of asthma. Although promising, clear evidence for FeNO as a robust asthma predictor in comparison to clinical scores is still lacking. Specific IgE and eosinophil counts remain the most consistent biomarkers for the identification of children at risk for asthma, and further studies are necessary to clarify the role of other biomarkers.

Factor XI deficiency enhances the pulmonary allergic response to house dust mite in mice independent of factor XII

Asthma is associated with activation of coagulation in the airways. The coagulation system can be initiated via the extrinsic tissue factor-dependent pathway or via the intrinsic pathway, in which the central player factor XI (FXI) can be either activated via active factor XII (FXIIa) or via thrombin. We aimed to determine the role of the intrinsic coagulation system and its possible route of activation in allergic lung inflammation induced by the clinically relevant human allergen house dust mite (HDM). Wild-type (WT), FXI knockout (KO), and FXII KO mice were subjected to repeated exposure to HDM via the airways, and inflammatory responses were compared. FXI KO mice showed increased influx of eosinophils into lung tissue, accompanied by elevated local levels of the main eosinophil chemoattractant eotaxin. Although gross lung pathology and airway mucus production did not differ between groups, FXI KO mice displayed an impaired endothelial/epithelial barrier function, as reflected by elevated levels of total protein and IgM in bronchoalveolar lavage fluid. FXI KO mice had a stronger systemic IgE response with an almost completely absent HDM-specific IgG₁ response. The phenotype of FXII KO mice was, except for a higher HDM-specific IgG₁ response, similar to that of WT mice. In conclusion, FXI attenuates part of the allergic response to repeated administration of HDM in the airways by a mechanism that is independent of activation via FXII.