Epidemiology of asthma exacerbations and their relation with environmental factors in the Basque Country

BACKGROUND

Asthma is a highly prevalent chronic inflammatory disease characterised by reversible airflow obstruction and hyperreactivity and inflammation of the airways. Factors that cause and/or trigger asthma attacks include host-related factors (genetic predisposition, obesity and sex) and environmental factors (allergens, infections, occupational sensitisation, smoking status, pollution and diet).

OBJECTIVE

To describe the epidemiology of asthma exacerbations (AEs) in the Basque Country and to explore its relationship with potentially associated environmental variables. We studied a total of 31,579 emergency department (ED) visits and 28,189 hospitalisations due to asthma. We describe the trends, incidence, seasonality and the influence of age and sex, as well as of exposure to NO2 , CO, PM, O3 , and pollen, temperature, relative humidity and flu status. We calculated the Pearson's R correlation coefficient for the study variables.

RESULTS

The incidence was 486 and 88.9 cases per 100,000 people for ED visits and hospitalisations, respectively. Slightly over half (53.5%) of the ED cases were male, while females represented 62.6% of the hospital admissions. Hospitalisations are tending to decrease in children and increase in over 64-year-olds. Peaks in cases occur at the beginning of autumn in children and in winter in adults. AEs were correlated positively with exposure to NO2 , CO and to the influenza virus and negatively with temperature and exposure to O3 . These relationships vary, however, with age and season.

CONCLUSIONS AND CLINICAL RELEVANCE

Rates of hospitalisation for AEs and trends in these rates over time are different in adults and children with the patterns varying by sex, season and environmental conditions.

Evaluation of the effect of pollution and fungal disease on Pinus radiata pollen allergenicity

BACKGROUND

Pollutants and other stressing factors like mold infection might increase the production of pathogen-related proteins in plants. Since this is invoked as one of the causes for the high prevalence of allergic diseases in developed countries, we aimed to determine the potential effect of environmental pollution, with or without mold infection of the trees, on the allergenic potency of pine pollen (Pinus radiata).

METHODS

Pine pollen samples were recovered from three selected areas: low polluted (A), highly polluted (B) and highly polluted and infected with fungi (Spheropsis sapinea) (C). The allergenic potency of pollen from areas A, B or C were compared in vivo in 35 pine pollen-allergic patients by skin prick test and specific IgE (sIgE) quantification. Pollen was also analyzed in vitro by SDS-PAGE immunoblotting, RAST inhibition and cDNA-AFLP (amplified fragment length polymorphism) to compare differences in proteins and mRNA expression.

RESULTS

The allergenic potency measured by prick test, sIgE and RAST inhibition was greater in pollen A, which was exposed to smaller amounts of NO(x), PM(10) and SO(2) but greater amounts of O(3). No differences were found in IgE-binding bands in immunoblotting or densitometry of the bands. In cDNA-AFLP, three homologous transcript-derived fragments were expressed in samples B only, with an expressed sequence tag related with stress-regulated gene expression.

CONCLUSIONS

A greater allergenic potency, in terms of skin tests and sIgE, is observed in pine pollen coming from unpolluted areas. We consider that this fact might be related to a higher exposure to ozone, resulting in a greater expression of allergenic proteins.