Early Pollen Sensitization in Children Is Dependent upon Regional Aeroallergen Exposure

Pollen and viruses contribute to spatio-temporal variation in asthma-related emergency department visits

BACKGROUND

Asthma exacerbations are an important cause of emergency department visits but much remains unknown about the role of environmental triggers including viruses and allergenic pollen. A better understanding of spatio-temporal variation in exposure and risk posed by viruses and pollen types could help prioritize public health interventions.

OBJECTIVE

Here we quantify the effects of regionally important Cupressaceae pollen, tree pollen, other pollen types, rhinovirus, seasonal coronavirus, respiratory syncytial virus, and influenza on asthma-related emergency department visits for people living near eight pollen monitoring stations in Texas.

METHODS

We used age stratified Poisson regression analyses to quantify the effects of allergenic pollen and viruses on asthma-related emergency department visits.

RESULTS

Young children (<5 years of age) had high asthma-related emergency department rates (24.1 visits/1,000,000 person-days), which were mainly attributed to viruses (51.2%). School-aged children also had high rates (20.7 visits/1,000,000 person-days), which were attributed to viruses (57.0%), Cupressaceae pollen (0.7%), and tree pollen (2.8%). Adults had lower rates (8.1 visits/1,000,000 person-days) which were attributed to viruses (25.4%), Cupressaceae pollen (0.8%), and tree pollen (2.3%). This risk was spread unevenly across space and time; for example, during peak Cuppressaceae season, this pollen accounted for 8.2% of adult emergency department visits near Austin where these plants are abundant, but 0.4% in cities like Houston where they are not; results for other age groups were similar.

CONCLUSIONS

Although viruses are a major contributor to asthma-related emergency department visits, airborne pollen can explain a meaningful portion of visits during peak pollen season and this risk varies over both time and space because of differences in plant composition.

How Do Pollen Allergens Sensitize?

Plant pollen is one of the main sources of allergens causing allergic diseases such as allergic rhinitis and asthma. Several allergens in plant pollen are panallergens which are also present in other allergen sources. As a result, sensitized individuals may also experience food allergies. The mechanism of sensitization and development of allergic inflammation is a consequence of the interaction of allergens with a large number of molecular factors that often are acting in a complex with other compounds, for example low-molecular-mass ligands, which contribute to the induction a type 2-driven response of immune system. In this review, special attention is paid not only to properties of allergens but also to an important role of their interaction with lipids and other hydrophobic molecules in pollen sensitization. The reactions of epithelial cells lining the nasal and bronchial mucosa and of other immunocompetent cells will also be considered, in particular the mechanisms of the activation of B and T lymphocytes and the formation of allergen-specific antibody responses.

Fungal allergic sensitisation in young rural Zimbabwean children: Gut mycobiome and seroreactivity characteristics

Background

The prevalence of allergic diseases has increased over the last few decades, with sensitisation to fungal allergens and gut microbiome dysbiosis implicated in this trend. The fungal community in the gut (mycobiome) has yet to be characterised and related to fungal allergic sensitisation. Thus, we characterised the gut mycobiome and related it to fungal sensitisation and seroreactivity among Zimbabwean children. We further determined the effect of host age, sex, Schistosoma haematobium infection and mycobiome composition on fungal sensitisation and seroreactivity.

Methods

Using shotgun metagenomic sequencing, we characterised the gut microbiome of stool samples of 116 preschool aged children (PSAC) (≤5 years old, 57(49.1%) male and 59 (50.9%) female). Sensitisation to common fungi in Zimbabwe was assessed using skin prick tests (SPTs). Allergen-specific IgM, IgA, IgG, IgE and IgG4 antibodies were quantified by ELISA. We analysed the relationship between fungal genera and SPT reactivity by ANOVA; fungal genera and IgE antibody reactivity by linear regression; variation in mycobiome abundance with host and environmental factors by PERMANOVA; SPT reactivity and host and environmental factors by logistic regression; seroreactivity and host and environmental factors by ANOVA.

Results

The mycobiome formed <1% of the sequenced gut microbiome and 228 fungal genera were identified. The most abundant genera detected were Protomyces, Taphrina, and Aspergillus. S.haematobium infection had a significant effect on fungal genera. Prevalence of SPT sensitisation to ≥1 fungal species was 96%, and individuals were frequently sensitised to Saccharomyces cerevisiae. Antibodies were detected in 100% of the population. There was no relationship between mycobiome abundance and IgE titres or IgE/IgG4 ratios for each fungal species; no significant differences between SPT reactivity and abundance of fungal species except for S. cerevisiae; and fungal seroreactivity did not significantly differ with age. There were some sex (m>f for, Epicoccum nigrum and Penicillium chrysogenum) and SPT reactivity -related differences in seroreactivity.

Conclusion

This is the first comprehensive characterisation of gut mycobiome and fungal allergic sensitisation of rural children in Zimbabwe. Although reported allergic disease is low there is a high percentage of sensitisation. Further studies with larger populations are required to understand the role of the mycobiome in allergic diseases.

Respiratory allergies: Salicaceae sensitization (Review)

Seasonal allergic rhinitis (SAR) is one of the most frequent chronic conditions of the modern world. Pollen carried by the wind from pollinated trees is a major source of SAR. Betulaceae, Oleaceae and Platanus are the most important sources of airway sensitization with regard to tree pollen and, therefore, they are included in the official recommendations of skin prick testing by different official societies. Salicaceae pollen is a moderate source of pollen sensitization. Conversely, large areas are covered with poplars and willows around the world. A number of studies from many countries showed that in some particular situations (large and compacted areas covered by Salicaceae, weather conditions, air pollution, urban ornamental vegetation), poplar and willow pollens may become of local importance in producing SAR. The aim of this review was to present a synthesis of information regarding Salicaceae pollen allergy showing that, if various unfavorable aspects are brought together, a minor problem (Salicaceae sensitization) can became a public health problem.

Eosinophilic esophagitis: comorbidities and atopic disease in Nevada

Eosinophilic esophagitis (EoE) is a rare, immune-mediated illness. We aimed to examine the comorbidities and sensitization patterns associated with an EoE diagnosis in Nevada. The study goal was two-fold: to determine the most common EoE comorbidities and sequela in the state of Nevada using healthcare utilization records across all settings and to determine the most common food and aeroallergens in histologically positive EoE pediatric patients using clinical sensitization data. Esophageal obstruction/stricture was the most frequently reported diagnosis in adults with EoE (29.5%). Among pediatrics, the highest ranking comorbidities included asthma (13.4%); diseases of the stomach, duodenum, and intestine (7.26%); allergies (7.01%); and gastroesophageal reflux disease (GERD) (3.69%). Additionally, the top sensitizations reported in histologically positive EoE patients were largely pollen related (82.9%). Atopic disease and specifically food allergens are commonly reported as comorbid conditions with EoE in the literature. However, our clinical pediatric data set from this study revealed that aeroallergen sensitizations far exceeded that of food allergens (82.9% aero-positive vs. 17.1% dood positive). The high presence of esophageal stricture/obstruction in adults could be indicative of late diagnosis; in addition, the aeroallergen sensitization in children could suggest different clinical management techniques necessary may be needed for this disease. Education among healthcare providers regarding the presence of aeroallergen sensitization in this population may result in earlier diagnoses and help reduce morbidity and the cost from this disease.

A description of eosinophilic esophagitis in the Southwestern state of Nevada

OBJECTIVES

Eosinophilic esophagitis (EoE) is a rare immune-mediated esophageal disorder that has been documented worldwide. Prior to this study, eosinophilic esophagitis had not been described in the Southwestern state of Nevada. Records containing positive eosinophilic esophagitis diagnosis codes were extracted from a large hospital utilization database and yielded over 2,000 records over 5 years (2013-2017).

METHODS

Descriptive statistics were used to identify the overall population demography. Logistic regression was used to determine the factors associated with an eosinophilic esophagitis event in Nevada.

RESULTS

Males were 2.93 times more likely (95% CI: 2.53, 3.41; p < 0.001) to have had an eosinophilic esophagitis event when compared to females. Older age was also significant; for each additional year in age the odds of having an eosinophilic esophagitis visit increased by 30% (95% CI: 1.28, 1.31; p < 0.001). Finally, individuals living in the Northern region had 1.95 higher odds of an eosinophilic esophagitis event than their Southern counterparts (OR = 1.95, 95% CI: 1.68, 2.26; p < 0.001).

CONCLUSIONS

The climate in Nevada makes this study novel, as the climate is unlike other studies reporting EoE disease prevalence. Previous atopic studies in Nevada report that warmer, drier weather leads to increased atopic illness and perennial pollen, which ultimately may be contributing to the higher than expected number of EoE records identified. Given the well-documented relationship between EoE and atopy, Nevada may be a susceptible region for this condition and an ideal location for future studies.

Number of seasonal exposures to Japanese cedar pollen increases the risk of sensitization: Observational study in Korean adults

Sensitization to seasonal allergens usually requires repeated exposure to them. However, research on the extent of exposure that increases the risk of sensitization to specific allergens is lacking. Therefore, we investigated the levels of exposure to Japanese cedar pollen that increased the risk of sensitization to it. A cross-sectional study was conducted with 857 college students living in Jeju, South Korea, as it is the only province in Korea where Japanese cedar pollen levels are high. Questionnaires about demographic characteristics were distributed and skin prick tests for allergic sensitization were performed. Sensitization rates of groups divided by residence period were 3.8% (less than 1 year), 1.8% (1–2 years), 8.5% (2–3 years), 10.3% (3–4 years), 14.8% (4–10 years), and 19.1% (over 10 years). Residence period was an influencing factor of sensitization rate to Japanese cedar pollen, and the cut-off value of the residence period that increased the risk of sensitization to Japanese cedar pollen was found to be 25 months. Repeated exposure to seasonal allergens was related to an increased sensitization rate in young adults. Our results suggested that exposure to Japanese cedar pollen for over two seasons could increase the risk in Korean adults.

Using high-resolution residential greenspace measures in an urban environment to assess risks of allergy outcomes in children

Despite reported health benefits of urban greenspace (gs), the epidemiological evidence is less clear for allergic disease. To address a limitation of previous research, we examined the associations of medium- and high-resolution residential gs measures and tree and/or grass canopies with allergic outcomes for children enrolled in the longitudinal cincinnati childhood allergy and air pollution study (ccaaps). We estimated residential gs based on 400 m radial buffers around participant addresses (n = 478) using the normalized differential vegetation index (ndvi) and land cover-derived urban greenspace (ugs) (tree and grass coverage, combined and separate) at 30 m and 1.5-2.5 m resolution, respectively. Associations between outdoor aeroallergen sensitization and allergic rhinitis at age 7 and residential gs measures at different exposure windows were examined using multivariable logistic regression models. A 10% increase in ugs-derived grass coverage was associated with an increased risk of sensitization to grass pollens (adjusted odds ratio [aor]: 1.27; 95% confidence interval = 1.02-1.58). For each 10% increase in ugs-derived tree canopy coverage, nonstatistically significant decreased odds were found for grass pollen sensitization, tree pollen sensitization, and sensitization to either (aor range = 0.87-0.94). Results similar in magnitude to ugs-tree canopy coverage were detected for ndvi and allergic sensitizations. High-resolution (down to 1.5 m) gs measures of grass- and tree-covered areas showed associations in opposite directions for different allergy outcomes. These data suggest that measures strongly correlated with tree canopy (e.g., ndvi) may be insufficient to detect health effects associated with proximity to different types of vegetation or help elucidate mechanisms related to specific gs exposure pathways.

Asthma, allergy, and obesity: Examining the relationship among Nevada children

OBJECTIVE

The majority of pediatric asthma is atopic, but whether pediatric obese asthma is atopic is indeterminate in the literature. In Nevada, children become sensitized to aeroallergens, a risk factor for asthma, at young ages. Additionally, Nevada children have high rates of obesity. Our objective is to determine whether elevated body mass index (BMI) is associated with asthma severity, allergen sensitization, and polysensitization.

METHODS

Medical records from a pediatric allergy clinic provided BMI percentile, physician-diagnosed asthma severity, skin prick test data, and sociodemographics such as age, race, sex, and insurance status from asthmatic patients. Descriptive statistics and binary and multinomial logistic regression were conducted.

RESULTS

In this population (N = 125) aged 1-16, 61% were male, 65% were white, and 74% had private health insurance. Sixty-five percent of children were under/healthy weight and 29% were overweight/obese. Asthma symptoms were moderate in 66% of the population, and severe in 18%. Nearly 85% of this population was atopic, and 82% were polysensitized. Sensitization and polysensitization occurred in all weight categories. Asthma severity and elevated BMI were not associated significantly. Overweight/obese children (≥85^th percentile) had lower odds of allergen sensitization (adjusted odds ratio 0.26, 95% CI = 0.85-0.78, p = 0.016) and polysensitization (adjusted odds ratio 0.30, 95% CI = 0.11-0.85, p = 0.023) than healthy weight children (<85^th percentile).

CONCLUSION

Although overweight children did show allergen sensitization, those who were overweight had lower odds of allergen sensitization and lower odds of polysensitization, as compared to normal weight asthmatic children. Elevated BMI was not a significant predictor of asthma severity.

Pollen Allergens for Molecular Diagnosis

Pollen allergens are one of the main causes of type I allergies affecting up to 30% of the population in industrialized countries. Climatic changes affect the duration and intensity of pollen seasons and may together with pollution contribute to increased incidences of respiratory allergy and asthma. Allergenic grasses, trees, and weeds often present similar habitats and flowering periods compromising clinical anamnesis. Molecule-based approaches enable distinction between genuine sensitization and clinically mostly irrelevant IgE cross-reactivity due to, e. g., panallergens or carbohydrate determinants. In addition, sensitivity as well as specificity can be improved and lead to identification of the primary sensitizing source which is particularly beneficial regarding polysensitized patients. This review gives an overview on relevant pollen allergens and their usefulness in daily practice. Appropriate allergy diagnosis is directly influencing decisions for therapeutic interventions, and thus, reliable biomarkers are pivotal when considering allergen immunotherapy in the context of precision medicine.

Immunological cross-reactivity between olive and grass pollen: implication of major and minor allergens

Background

Grasses and olive trees are the most common sources of allergenic pollen worldwide. Although they share some allergens, there are few studies analyzing the in vitro cross-reactivity between them. The aim was to define the cross-reactivity between Olea europaea and Phleum pratense using well-characterized sera of allergic children from Madrid, Spain.

Methods

66 patients (mean age 10.32+/−4.07 years) were included in the study. All suffered from rhinoconjuntivitis and/or asthma and had a positive skin test and/or specific IgE determination to olive and grass pollen. Serum sIgE to individual allergens was conducted and sIgE against different grass species and olive was also determined by ELISA. Inhibition assays were performed using two serum sources, containing, or not, sIgE to minor allergens. Mass spectrometry analysis was performed in both extracts.

Results

59/66 (89.39%) children had a positive sIgE determination by ELISA to grasses and 57/66 (86.36%) to olive pollen. There was no significant correlation between sIgE levels to grass and olive. Inhibition assays demonstrated no cross-reactivity between P. pratense and olive pollen when using the pool containing mainly sIgE to major allergens, whereas minimal to moderate cross-reactivity was detected when the serum contained high sIgE titers to minor allergens. Proteomic analyses revealed the presence of 42 common proteins in grasses and olive pollens.

Conclusion

No in vitro cross-reactivity was observed when sIgE was mainly directed to major allergens. In our population, sensitization to olive and grasses is not due to cross-reactivity. The contribution of the major allergens seems to be determinant.