[Climate change and type I allergies at the workplace]

The consequences of climate change, the increasing frequency, duration and intensity of extreme events such as excessive drought, heat waves, large-scale forest fires, heavy rainfall and associated flooding also affect workers' conditions in the workplace in many ways. Allergic diseases of the respiratory tract and skin due to workplace exposure can also arise or be influenced by direct and indirect consequences of climate change. This affects outdoor workers not only through increased exposure to pollen allergens, but also through climate-related increases in typical workplace allergens. As an indirect effect of climate change, manufacturing processes and exposure at workplaces are changing, which can also cause new sensitization and allergies. Lifestyle changes, which are primarily intended to contribute to climate protection and sustainability, can also lead to new or changed products and thus to changed manufacturing processes and exposures in the workplace, so this should also be considered an indirect effect of climate change on the health of workers. The emergence of new occupational sources of sensitization due to new or changed allergen exposures must be considered in the context of occupational health and safety and requires proactive measures to protect workers.

Genes related to allergen exposure in allergic rhinitis: a gene-chip-based study in a mouse model

BACKGROUND

The typical clinical symptoms of allergic rhinitis (AR) are known to be associated with allergen exposure; however, the underlying mechanisms are not fully understood. We wanted to gain a comprehensive view of the molecular mechanisms related to allergen exposure in a well-controlled mouse model of AR.

METHODS

An OVA-induced AR model was developed. Two hours and 4 weeks after the last OVA challenge, AR symptoms and local immune responses were assessed. At the same time, differentially expressed genes (DEG) in nasal mucosa were identified by gene expression microarray and further analyzed by bioinformatics methods. Verification of DEG was done by quantitative RT-PCR and immunohistochemistry.

RESULTS

The number of nasal rubbings and sneezes, serum OVA-specific IgE concentrations, and the number of neutrophils and eosinophils in the nasal mucosa were significantly increased at 2 h and decreased at 4 weeks after the last allergen challenge compared to controls. A total of 2119 DEG were identified, and their expression dynamics were clustered into 8 profiles. Enriched functions in Profile 5, which had a similar trend to clinical features, were mainly related to inflammatory and immune response to environmental factors, eosinophils and neutrophils chemotaxis, and cell migration. Gene co-expression Network for genes from profile 5 identified BCL3, NFKB2, SOCS3, and CD53 having a higher degree. Profile 6 showed persistence of inflammatory and immune response at 4 weeks after the last allergen challenge. Olfactory and coagulation functions were enriched mainly in profiles with downward trends.

CONCLUSIONS

A wide range of genes with sequential cooperative action were identified to be associated with allergen exposure in AR. BCL3 may be the most vital in symptoms manifestation. Moreover, some inflammatory responses persisted for a period after allergen exposure, supporting a new treatment strategy of targeting inflammation out of season. This study may contribute to a better understanding of AR pathogenesis and provide potential therapeutic targets for AR patients.

Indoor Environmental Factors May Modify the Response to Mouse Allergen Reduction Among Mouse-Sensitized and Exposed Children with Persistent Asthma

BACKGROUND

Whether concomitant home exposures modify the effectiveness of mouse allergen reduction among mouse-sensitized children with asthma is unknown.

OBJECTIVE

To determine whether a lower baseline home mouse allergen level, lower particulate matter 10 μ or less (PM₁₀), and the absence of sensitization and exposure to other indoor allergens are associated with greater improvements in asthma associated with mouse allergen reduction.

METHODS

A secondary analysis of a randomized clinical trial of a home mouse allergen intervention was performed to examine the effect of 3 indoor factors on the relationship between mouse allergen reduction and a range of asthma outcomes.

RESULTS

Participants (N = 297) were predominantly minority (78% African American, 22% Hispanic) and publicly insured (88%). Higher baseline mouse allergen levels were associated with a greater response to mouse allergen reduction for several symptom and exacerbation outcomes. Lower indoor PM₁₀ levels were associated with a greater response to mouse allergen reduction for several symptom outcomes, but not exacerbation outcomes. Overall, sensitization and exposure to other indoor allergens did not appear to modify the effect of mouse allergen reduction.

CONCLUSIONS

In this population of predominantly low-income children with persistent asthma and mouse sensitization, mouse allergen reduction was associated with improvements in asthma, especially among those with high baseline mouse allergen exposure. Lower indoor PM₁₀ was associated with greater improvements in asthma symptoms.

Mite Molecular Profile in the Th2-Polarized Moderate-to-Severe Persistent Asthma Endotype Subjected to High Allergen Exposure

BACKGROUND

The association among the IgE responses to prevailing groups of house dust mite (HDM) allergens in the concurrent asthma phenotypes has not been determined.

OBJECTIVE

The aim of the present study lays on a component-resolved diagnosis (CRD) model to investigate the mite molecular signature in subjects with type-2 inflammation asthma.

METHODS

We selected patients showing a clinically relevant sensitization to HDMs with moderate-to-severe persistent asthma. Skin prick test (SPT) with standardized mite extracts, a broad customized CRD serum sIgE panel including 9 Dermatophagoides pteronyssinus allergens and the related protein allergenic characterization, was investigated in all serum samples.

RESULTS

Ninety out of 93 (96.77%) patients with a positive SPT to HDM showed a concordant sIgE (≥0.35 kUA/L) to the crude extract of D. pteronyssinus. Major allergens (Der p 2, Der p 23, and Der p 1) were present in >70% of all subjects, with mid-tier allergens (Der p 5, Der p 7, and Der p 21) reaching up to 51% in the present cohort. A complex pleomorphic repertoire of HDM molecules recognized by IgE was depicted, including 38 distinct profiles.

CONCLUSIONS AND CLINICAL RELEVANCE

The proposed CRD panel approach, containing the most prevalent HDM allergens, appeared to be sufficient to obtain a precise D. pteronyssinus molecular diagnosis in asthmatics with a climate-dependent high-mite allergen exposure and coexisting sensitization. A dominant role of both major and mid-tier allergens has been confirmed in moderate and severe persistent asthmatics with the preponderant Th2-high endotype.

Identification of Seasonal Variations of Antibodies against PR-10-Specific Epitopes Can Be Improved Using Peptide-Phage Display

BACKGROUND

In pollinosis patients, allergen-specific antibody titers show seasonal variations. Little is known about these variations at the epitope level.

OBJECTIVES

We aimed at investigating seasonal variations on the level of allergen epitope recognition in patients with Bet v 1-related food allergy using a peptide phage display approach.

METHODS

Serum samples collected over 1 year from 4 patients of the placebo arm of the birch-associated soya allergy immunotherapy trial were included. To identify epitopes from Bet v 1-related food allergens, patient sera were used in peptide phage display experiments. In silico analysis of enriched allergen-related motifs was performed.

RESULTS

We identified epitope motifs related to Bet v 1 and its homologs in soya and hazelnut (Gly m 4 and Cor a 1, respectively) that were enriched in accordance with birch and hazel pollen exposure. Within several weeks after the birch pollen season peak, the pattern of identified epitope motifs differed considerably among patients. Data for amino acid preferences in homologous Bet v 1 and Cor a 1 epitope motifs identified for one of the investigated patients suggest changes in concentration or specificity of serum antibodies for the Cor a 1 epitope motif.

CONCLUSIONS

Peptide phage display data suggest an impact of birch and hazel pollen exposure on the recognition pattern of Bet v 1-like allergen epitopes. Epitope-oriented analyses could provide deeper, personalized details regarding the allergen epitope recognition influenced by pollen exposure beyond the capability of current methods.

Reduction in mouse allergen exposure is associated with greater lung function growth

BACKGROUND

Current childhood asthma therapies have little effect on lung function trajectory.

OBJECTIVE

We sought to determine whether mouse allergen exposure reduction is associated with lung function growth in mouse-sensitized/exposed asthmatic children.

METHODS

Three hundred fifty mouse-sensitized/exposed asthmatic children (5-17 years old) were enrolled in a 1-year randomized trial of integrated pest management plus education versus education alone. Prebronchodilator/postbronchodilator spirometry was performed at baseline and 6 and 12 months, and bedroom floor mouse allergen levels were measured every 3 months. Mouse allergen reduction was defined as a 75% or greater decrease in mouse allergen levels from baseline. Treatment groups were combined for analyses because there were no differences in outcomes between groups. Changes in lung function over time were modeled, adjusting for age, sex, race, atopy, group, and bronchodilator reversibility and including an interaction term (allergen reduction*time).

RESULTS

The study population was predominantly black (79.4%) and low income (66.3% [<$30,000]). At baseline, the median mouse allergen level was 5.7 μg/g (interquartile range, 1.5-22.8 μg/g), and the mean (SD) prebronchodilator FEV₁/forced vital capacity ratio was 80.2% (9.0%). Ninety-two (26.3%) participants had 75% or greater reduction in mouse allergen levels. For a 10-year-old black boy, 75% or greater allergen reduction was associated with an increase in prebronchodilator FEV₁ of 238 mL/y (95% CI, 177-299 mL/y), whereas less than 75% allergen reduction was associated with an increase in prebronchodilator FEV₁ of 131 mL/y (95% CI, 97-166 mL/y). Estimated differences in prebronchodilator and postbronchodilator FEV₁ growth were as follows: 107 mL/y (95% CI, 37-177 mL/y; P_int = .003) and 48 mL/y (95% CI, -17 to 113 mL/y; P_int = .15), respectively. Estimated differences in prebronchodilator and postbronchodilator forced expiratory flow at 25% to 75% of vital capacity growth were as follows: 182 mL/y (95% CI, 61-304 mL/y; P_int = .003) and 181 mL/y (95% CI, 48-314 mL/y; P_int = .008), respectively.

CONCLUSION

Mouse allergen reduction is associated with greater increases in prebronchodilator FEV₁ and prebronchodilator/postbronchodilator forced expiratory flow at 25% to 75% of vital capacity over 1 year among sensitized/exposed asthmatic children.

Early-life inhalant allergen exposure, filaggrin genotype, and the development of sensitization from infancy to adolescence

Background

We hypothesized that filaggrin (FLG) loss-of-function mutations modify the effect of allergen exposure on the development of allergic sensitization.

Objective

We sought to determine whether early-life exposure to inhalant allergens increases the risk of specific sensitization and whether FLG mutations modulate these odds.

Methods

In a population-based birth cohort we measured mite, cat, and dog allergen levels in dust samples collected from homes within the first year of life. Sensitization was assessed at 6 time points between infancy and age 16 years. Genotyping was performed for 6 FLG mutations.

Results

In the longitudinal multivariable model (age 1-16 years), we observed a significant interaction between FLG and Fel d 1 exposure on cat sensitization, with the effect of exposure being significantly greater among children with FLG mutations compared with those without (odds ratio, 1.36; 95% CI, 1.02-1.80; P = .035). The increase in risk of mite sensitization with increasing Der p 1 exposure was consistently greater among children with FLG mutations, but the interaction did not reach statistical significance. Different associations were observed for dogs: there was a significant interaction between FLG and dog ownership, but the risk of sensitization to any allergen was significantly lower among children with FLG mutations who were exposed to a dog in infancy (odds ratio, 0.16; 95% CI, 0.03-0.86; P = .03).

Conclusions

FLG loss-of-function mutations modify the relationship between allergen exposure and sensitization, but effects differ at different ages and between different allergens.

Do Baseline Asthma and Allergic Sensitization Characteristics Predict Responsiveness to Mouse Allergen Reduction?

BACKGROUND

Mouse allergen reduction is associated with improvements in asthma among sensitized and exposed children, but whether clinical characteristics predict responsiveness to allergen reduction is unclear.

OBJECTIVE

To examine the effects of clinical characteristics on relationships between mouse allergen reduction and asthma outcomes.

METHODS

We performed a secondary analysis of data from a randomized clinical trial of a mouse allergen intervention, examining the effects of atopy, demographic characteristics, lung function, asthma control, and asthma severity on relationships between mouse allergen reduction and asthma outcomes.

RESULTS

Participants were predominantly low-income and minority (78% black, 22% Hispanic), and had persistent asthma. Among less atopic participants (<6 positive skin prick test results), each 50% reduction in mouse allergen was associated with fewer symptoms (incidence rate ratio [95% CI]: maximal symptoms: 0.94 [0.92-0.96]). There was little effect of mouse allergen reduction on symptoms among more atopic participants (P > .05). The interactions between atopic status and mouse allergen reduction were statistically significant for all symptom outcomes; however, there was no evidence that atopic status influenced the effect of mouse allergen reduction on exacerbation-related outcomes. Older children (≥9 years) tended to experience greater improvement in some asthma outcomes with reduction in mouse allergen exposure than younger children. There was no evidence that either mouse-specific IgE or lung function influenced the effect of mouse allergen reduction on any asthma outcomes.

CONCLUSIONS

Although there may be variability in the clinical response to mouse allergen reduction among low-income, minority children with asthma, there were no clinical characteristics that clearly identified a subgroup at which the intervention should be targeted.

Defining Pollen Seasons: Background and Recommendations

PURPOSE OF REVIEW

The definition of a pollen season determines the start and the end of the time period with a certain amount of pollen in the ambient air. Different pollen season definitions were used for a long time including the use of different terms for data and methods used to define a pollen season. Recently suggested pollen season definitions for clinical trials were tested and applied for the first time to more aeroallergens.

RECENT FINDINGS

This is a review on pollen season definitions and the latest recommendations. Recently, proposed terminology in aerobiology is promoted here in order to support reproducibility and repeatability in research. Two pollen season definitions, one based on percentages and one based on pollen concentrations, were tested. Percentage definitions can be recommended for standard aerobiological routines and for retrospective applications, whereas pollen concentrations definitions can be recommended for prospective applications such as clinical trials.

Indoor allergen levels in settled airborne dust are higher in day-care centers than at home

BACKGROUND

Early-life sensitization to indoor allergens predicts asthma development. The aim of this study was to compare allergen concentrations in day-care centers (DCC) with those in private homes.

METHODS

Settled airborne dust was collected 4 times a year from 20 German DCC (620 samples) and from the homes of children and day-care workers (602 samples) using electrostatic dust collectors (EDC). The samples were analyzed with fluorescence enzyme immunoassays recognizing domestic mite allergens (DM), Fel d 1, Can f 1, and Mus m 1. Pet allergen thresholds that discriminate samples from homes with cats or dogs from those without were calculated using receiver-operating characteristics. Influences on allergen levels were analyzed using multilevel models.

RESULTS

Allergen loads were on average higher in DCC than in homes. In DCC, 96% of the samples were positive for DM, 95% for Can f 1, 90% for Fel d 1, and 83% for Mus m 1. In homes, 84% contained DM, 48.5% Can f 1, 33% Fel d 1, and 43% Mus m 1. The threshold level for homes with dogs was 75 ng/m² Can f 1 (96.8% sensitivity, 96% specificity), and the threshold level for homes with cats was 46 ng/m² Fel d 1 (92% sensitivity, 94.9% specificity). In DCC, Can f 1 and Fel d 1 loads were higher than these thresholds in 37% and 54% of the samples, respectively. Allergen levels were significantly influenced by the season and room type; however, carpets on floors had no influence.

CONCLUSIONS

Mite, mouse, cat, and dog allergens were mostly higher in DCC than in homes. Exposure to dog and cat allergens in DCC often reached levels of households with pets.

Immigrant Respiratory Health: a Diverse Perspective in Environmental Influences on Respiratory Health

PURPOSE OF REVIEW

The aim of this review is to examine the prevalence of and impact of environmental exposures in the workplace and home on immigrant respiratory health in the USA.

RECENT FINDINGS

Few studies report levels of workplace and home environmental exposures for immigrant children and adults, and documenting these findings is an important first step to addressing their respiratory health concerns. Rates of respiratory disease are lowest upon first arrival and increase with duration of residency in the USA. Community Health Workers may be an efficacious intervention to reducing exposures and improving lung health among immigrant populations. Immigrant children and adults have a high risk of occupational and home environmental exposures that can negatively affect their respiratory health. While limited studies exist, more documentation of these exposures and their impact on immigrant person's respiratory health are needed to begin to tackle these disparities.

Lung responses in murine models of experimental asthma: Value of house dust mite over ovalbumin sensitization

Ovalbumin (OVA) sensitization has limitations in modelling asthma. Thus, we examined the value of allergic sensitization using a purified natural allergen, house dust mite (HDM), over the sensitization performed with OVA. Mice were sham-treated, or sensitized with OVA- or HDM with identical chronology. Airway resistance, tissue damping and elastance were assessed under control conditions and after challenging the animals with methacholine (MCh) and the specific allergen. Inflammatory profile of the bronchoalveolar lavage fluid was characterized and lung histology was performed. While no difference in the lung responsiveness to the specific allergen was noted, hyperresponsiveness to MCh was observed only in the HDM-sensitized animals in the lung peripheral parameters. Lung inflammation differed between the models, but excessive bronchial smooth muscle remodelling occurred only with OVA. In conclusion, we demonstrate that a purified natural allergen offers a more relevant murine model of human allergic asthma by expressing the key features of this chronic inflammatory disease both in the lung function and structure.

Sensitization and Exposure to Pets: The Effect on Asthma Morbidity in the US Population

BACKGROUND

Although pets are found in more than 50% of US homes, the effect of pet allergen exposure on asthma morbidity in the US population is not well documented.

OBJECTIVE

To determine the effect of dog and cat allergen exposures on asthma morbidity in the US population.

METHODS

The National Health and Nutrition Examination Survey is a representative sample of civilian US population. Data on asthma, dog and cat allergen levels in bedroom dust, as well as specific IgE to dog and cat were analyzed for all participants 6 years or older.

RESULTS

Pets are common in the United States, with more that 50% of households having a dog or a cat or both. The prevalence of allergic sensitization in the National Health and Nutrition Examination Survey population was similar for dog and cat, with both being approximately 12%. Among those who were sensitized, exposure to elevated levels of pet allergens was associated with an increased prevalence of asthma and asthma attacks. Indeed, 44.2% of the asthma attacks were attributable to exposure to high levels of dog allergen in the bedroom among patients with asthma sensitive to dog and 30.3% were attributable to cat allergen exposure among the comparable cat-sensitive and exposed group. Projecting these results to the US population indicates more than 1 million increased asthma attacks each year for the dog-sensitive and exposed group and more than 500,000 increased asthma attacks for the cat-sensitive and exposed population of patients with asthma.

CONCLUSIONS

Exposure to elevated levels of dog and cat allergens among those sensitized individuals with asthma is associated with excess asthma attacks. Reducing pet allergen exposures has the potential for a significant decrease in asthma morbidity.

Immune responses to different patterns of exposure to ovalbumin in a mouse model of allergic rhinitis

Allergic rhinitis (AR) has been a significant healthcare burden on individuals and society. However, the detailed effect of different patterns of allergen exposure on the development of AR remains controversial. A mouse model of AR was established to address the complex relationships between allergen exposure and the development of AR. Allergic symptom, OVA-specific IgE in serum and nasal lavage fluid, allergic inflammation in nasal tissues were evaluated after intranasal sensitization and challenge of ovalbumin (OVA) in mice treated with two different doses of allergen for different sensitized durations. Exposure to different doses and sensitized durations of OVA were capable of inducing allergic nasal response. Repetitive OVA exposure in the sensitization phase induced the recruitment of eosinophils and goblet cell hyperplasia. The level of OVA-specific IgE in serum depended on OVA exposure and was mediated in a duration-related manner. In addition, mice treated with low-dose OVA for prolonged duration manifested the major features of human local allergic rhinitis. There were dose- and duration-related effects of allergen exposure on the development of AR. LAR was associated with repetitive exposure to low-dose allergen. Thus, allergen avoidance should be an important aim of AR management.

Can the presence of cat/dog at home be considered the only criterion of exposure to cat/dog allergens? A likely underestimated bias in clinical practice and in large epidemiological studies

An important aspect of allergic sensitization to furry animals is the association of dog and cat exposure in early childhood with the incidence of respective allergies later in life. This topic is very controversial, because some authors have found a "facilitating" effect, while others have noticed a "protective" or even no significant effect in individuals living in urban areas. It is likely that some biases could be responsible of these contradictory findings. Cat/dog ownership or their presence in indoor environments are considered usually the main criteria to assess the exposure to these pets in studies' questionnaires. Even in clinical practice "are there animals at home?" is the common query usually done when collecting anamnestic data. In our opinion, these commonly used questions should not be considered the main index of exposure to pet allergens, because they can lead to erroneous interpretation of the clinical significance of positive skin prick tests for pet allergens as well as of the real risk of exposure to allergens of dog/cat in epidemiological studies. Consequently, we suggest a new, more realistic, classification of modalities of exposure to pet allergens in "real life" based on five possible conditions.

Domestic exposure to fungal allergenic particles determined by halogen immunoassay using subject's serum versus particles carrying three non-fungal allergens determined by allergen-specific HIA

Studies that estimate indoor aeroallergen exposure typically measure a pre-selected limited range of allergens. In this study, inhalable aeroallergen particles were quantified using the halogen immunoassay (HIA) to determine the contribution of fungal and non-fungal aeroallergens to total allergen exposure. Bioaerosols from 39 homes of fungal-allergic subjects were sampled using inhalable fraction samplers and immunostained by HIA using resident subject's immunoglobulin E (IgE) to detect allergen-laden particles. Fungal aerosols as well as particles carrying mite, cat, and cockroach allergens were identified and enumerated by HIA. Reservoir dust-mite (Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergen concentrations were quantified by ELISA. Fungal particles that bound subject's IgE in the HIA were 1.7 (bedroom)- and 1.4 (living room)-fold more concentrated than Der p 1, Fel d 1, and Bla g 1 allergen particles combined. Predominant fungal conidia that bound IgE were derived from common environmental genera including Cladosporium and other fungi that produce amerospores. Airborne mite, cat, and cockroach allergen particle counts were not associated with reservoir concentrations determined by ELISA. This study demonstrates that inhalable fungal aerosols are the predominant aeroallergen sources in Sydney homes and should be considered in future exposure assessments.

PRACTICAL IMPLICATIONS

Indoor allergen exposure assessment studies have primarily focused on a limited range of allergen sources in samples derived from reservoir dust samples. Using an innovative immunodiagnostic approach, this study demonstrates that fungal bioaerosols are the dominant source of aeroallergen exposure in the domestic environment, providing unique insight into domestic aeroallergen exposure.