Links between Pollen, Atopy and the Asthma Epidemic

Abstract

Pollen allergy has been found in 80–90% of childhood asthmatics and 40–50% of adult-onset asthmatics. Despite the high prevalence of atopy in asthmatics, a causal relationship between the allergic response and asthma has not been clearly established. Pollen grains are too large to penetrate the small airways where asthma occurs. Yet pollen cytoplasmic fragments are respirable and are likely correlated with the asthmatic response in allergic asthmatics. In this review, we outline the mechanism of pollen fragmentation and possible pathophysiology of pollen fragment-induced asthma. Pollen grains rupture within the male flowers and emit cytoplasmic debris when winds or other disturbances disperse the pollen. Peak levels of grass and birch pollen allergens in the atmosphere correlated with the occurrence of moist weather conditions during the flowering period. Thunderstorm asthma epidemics may be triggered by grass pollen rupture in the atmosphere and the entrainment of respirable-sized particles in the outflows of air masses at ground level. Pollen contains nicotinamide adenine dinucleotide phosphate (reduced) oxidases and bioactive lipid mediators which likely contribute to the inflammatory response. Several studies have examined synergistic effects and enhanced immune response from interaction in the atmosphere, or from co-deposition in the airways, of pollen allergens, endogenous pro-inflammatory agents, and the particulate and gaseous fraction of combustion products. Pollen and fungal fragments also contain compounds that can suppress reactive oxidants and quench free radicals. It is important to know more about how these substances interact to potentially enhance, or even ameliorate, allergic asthma.

Chamber catalogues of optical and fluorescent signatures distinguish bioaerosol classes

“…Because of this phenomenon, the EOD distributions for pollen grains are much wider than their fungal or bacterial counterparts, and the means of these distributions are less than unadulterated pollen grains, some of which have true optical diameters larger than 10 µm. These results are consistent with laboratory and environmental studies which indicate that pollen grain fragmentation routinely occurs in the atmosphere (D'Amato et al, 2007;Miguel et al, 2006;Taylor et al, 2002Taylor et al, , 2007. The pollens assembled together based on the ascendancy of type C fluorescence and their markedly higher fluorescence intensities relative to the other bioaerosol classes observed (Fig.…”

Sensitization to profilin in the Central region of Portugal

“…Patients from the Inland region group were significantly more frequently sensitized to pollens than that from Coastal region group. This is probably related to the higher pollen counts found in the Inland region (SPAIC/Schering-Plough/CIPA, 1999), which may cause higher levels of allergic sensitization in the people exposed (Jarvis and Burney, 1998;Taylor et al, 2007).…”

“…The high allergen exposure namely to pollens, is one of the pointed factors that has been linked with the increase in prevalence of allergic diseases such as asthma, and rhinoconjunctivitis (Jarvis and Burney, 1998;Taylor et al, 2007;Gilmour et al, 2006). Climate changes result in an increase of the allergen burden, a fact that combined with pollutant exposures, can act synergistically to enhance the allergic response, and increase respiratory symptoms (Gilmour et al, 2006;D'Amato et al, 2007a,b;Beggs, 2004).…”

Reproducibility between counts of airborne allergenic pollen from two cities in the East Midlands, UK

“…Airborne pollen grains are an established cause of allergy related respiratory symptoms in predisposed subjects (Epton et al 1997), being the primary cause of seasonal allergic rhinitis, and an important cause of asthma (Peternel et al 2004, Taylor et al 2007). In recent decades allergies due to pollen have greatly increased throughout the world, especially in large cities and industrialised areas (Peternel et al 2004;Caiola et al 2002;D'Amato et al 2007).…”