Associations between sensitization to perennial/seasonal allergens and childhood asthma

Optimizing Identification of Allergic Sensitization to Seasonal Inhalant Allergens in the USA: Implications for Constructing Optimal Panels to Evaluate Patients with Allergy

INTRODUCTION

While a specific number and type of antigens are recognized to detect perennial inhalant allergies, the optimal number and combination of allergens to reliably identify seasonal allergic sensitization is unclear due to limited national data. This study analyzed aeroallergen testing data from a large US clinical reference laboratory to provide guidance for optimizing seasonal allergen test selection.

METHODS

The 2019 serum IgE tests for seasonal inhalant allergens were identified from the Quest Diagnostics database. Patients with results for at least 1 of 31 seasonal allergens across 4 allergen classes (11 trees, 7 weeds, 5 grasses, and 8 molds) were analyzed. A step-by-step conditional approach was employed to determine the minimum number and species of allergens needed to identify at least 98% of sensitized patients for each class.

RESULTS

Of 88,042 patients tested for ≥1 seasonal allergen, 1.5%, 1.8%, 1.3%, and 1.6% were tested for all trees, weeds, grasses, and molds, respectively. Of those tested for all allergens within a class, 40.4%, 38.6%, 29.5%, and 21.2% were sensitized to at least one tree, weed, grass, or mold allergen, respectively. Identification of ≥98% of sensitized patients within a class required 8 allergens for trees (mountain cedar, maple box elder, walnut, white ash, elm, birch, cottonwood, and hickory/pecan), 5 for weeds (common ragweed short, rough pigweed, English plantain, lamb's quarters/goosefoot, and Russian thistle), 3 for grasses (June/Kentucky blue grass, Johnson grass, and Bermuda grass), and 7 for molds (Alternaria alternata, Aspergillus fumigatus, Mucor racemosus, Epicoccum purpurascens, Penicillium notatum, Helminthosporium halodes, and Fusarium moniliforme).

CONCLUSION

A minimum of 23 antigens is required to optimally detect sensitization to four classes of seasonal allergens (i.e., ≥98% identification). The addition of these allergens to unique perennial allergens (cat, dog, mouse, cockroach, and 2 dust mite species) results in a comprehensive elucidation of inhalant allergen sensitization. This knowledge provides a pivotal guide for clinical laboratories as they construct allergen panels to optimize diagnostic yield.

Allergen skin test responses in broad U.S. asthma population in those with and without rhinitis

Background: Asthma and allergic rhinitis are pathologically interlinked conditions. Despite skin testing (ST) being pivotal for evaluating allergic sensitization, U.S. data that date back to 1960s on ST reactivity patterns in subjects with asthma remain sparse. Objective: The purpose of this study was to elucidate seasonal, perennial ST responses, and their relationship with asthma severity, early versus late onset disease, and immunoglobulin E (IgE) levels. Methods: Five hundred patients with asthma were randomly selected from the National Jewish Health electronic medical record over a 3-year span. Demographic, clinical, and allergen ST reactivity data for a battery of seasonal and perennial allergens were procured, including total IgE levels, asthma onset, and severity, by using t-tests, χ² tests, and Analysis of Variance (ANOVA), patterns of reactivity were assessed for overall, seasonal, and perennial allergens in relation to IgE levels, asthma onset, and severity. Results: Of the 500 patients, 398 were analyzed. 63.3% were women, 50.1% had adult-onset asthma, and 86.1% had rhinitis; 75.3% tested positive to one or more allergens, with men demonstrating higher overall (p = 0.039) and perennial (p = 0.035) sensitization. ST reactivity varied based on the presence of rhinitis for seasonal (p = 0.028) but not perennial (p = 0.733) allergens. Asthma severity was not significantly associated with ST reactivity (p > 0.10). ST positivity for perennial (p < 0.001) but not seasonal (p = 0.128) allergens was higher in childhood-onset asthma versus adult-onset asthma despite both groups having a large percentage of reactors. Elevated IgE levels correlated with ST reactivity (p < 0.01). Conclusion: Our study represents a unique comprehensive evaluation of ST reactivity in a U.S. asthma population, which is lacking in the literature, when factoring in asthma onset, severity, and IgE levels. Our findings underscore the importance of allergen sensitization in asthma, regardless of severity, concurrent rhinitis symptoms, or asthma onset, which challenge some of the prevailing assumptions about the relationship between allergen sensitization and asthma onset.

Assessing the relevance of allergenic pollen in indoor environments-current knowledge base and research needs

Airborne pollen allergens-a relevant component of bioaerosols and, therefore, of airborne particulate matter-are considered an important metric in air quality assessments. Although the measurement of airborne pollen allergen concentrations in outdoor environments (namely, in urban areas) has been recognized as a key environmental health indicator, no such obligation exists for indoor environments (dwellings or occupational settings). However, people spend most of their daily time (80-90%) indoors, where the majority of their exposure to air pollution, including pollen allergens, occurs. Nonetheless, the relative importance of airborne pollen allergen exposure indoors differs from outdoors because of differences in pollen loads, sources, dispersion, and degree of penetration from the outdoor surroundings, as well as the differences in the allergenic pollen profiles. In this brief review, we mined the literature over the last 10 years to summarize what existing measurements reveal about the relevance of airborne allergenic pollen in indoor environments. The research priorities on this topic are presented, highlighting the challenges and the motivations for obtaining pollen data in built environments which are key to understand the extent and mechanisms of human exposure to airborne pollen allergens. Thus, we provide a comprehensive assessment of the relevance of airborne allergenic pollen in indoor environments, highlighting knowledge gaps and research needs related to their health effects.

Seasonal Variation in miR-328-3p and let-7d-3p Are Associated With Seasonal Allergies and Asthma Symptoms in Children

OBJECTIVE

MicroRNAs (miRs) are small non-coding RNA molecules of around 18-22 nucleotides that are key regulators of many biologic processes, particularly inflammation. The purpose of this study was to determine the association of circulating miRs from asthmatic children with seasonal variation in allergic inflammation and asthma symptoms.

METHODS

We used available small RNA sequencing on blood serum from 398 children with mild-to-moderate asthma from the Childhood Asthma Management Program. We used seasonal asthma symptom data at the study baseline and allergen affection status from baseline skin prick tests as primary outcomes. We identified differentially expressed (DE) miRs between pairs of seasons using DESeq2. Regression analysis was used to identify associations between allergy status to specific seasonal allergens and DE miRs in 4 seasons and between seasonal asthma symptom data and DE miRs. We performed pathway enrichment analysis for target genes of the DE miRs using DAVID.

RESULTS

After quality control, 398 samples underwent differential analysis between the 4 seasons. We found 52 unique miRs from a total of 81 DE miRs across seasons. Further investigation of the association between these miRs and sensitization to seasonal allergens using skin prick tests revealed that 26 unique miRs from a total of 38 miRs were significantly associated with a same-season allergen. Comparison between seasonal asthma symptom data revealed that 2 of these 26 miRs also had significant associations with asthma symptoms in the same seasons: miR-328-3p (P < 0.03) and let-7d-3p (P < 0.05). Enrichment analysis showed that the most enriched pathway clusters were Rap1, Ras, and MAPK signaling pathways.

CONCLUSION

Our results show seasonal variation in miR-328-3p and let-7d-3p are significantly associated with seasonal asthma symptoms and seasonal allergies. These indicate a potentially protective role for let-7d-3p and a deleterious role for miR-328-3p in asthmatics sensitized to mulberry. Further work will determine whether these miRs are drivers or results of the allergic response.