In two separate studies, scientists suggest that one reason for allergies may be malfunction of the respiratory epithelium, allowing allergens to bind to, enter, and travel through the epithelium. They suggest that the gene expression in allergic patients changes between spring and winter in a way that affects protein transport and the cytoskeleton.
Studies on the mechanisms of allergy has focused on the understanding of aberrant immunoresponses. Only lately has the role of epithelium as the first line of defense against allergens been realized.
The research groups at the Helsinki University and Helsinki University Central Hospital in collaboration with several other Finnish research groups aimed to clarify what happens in the epithelium immediately after allergen exposure and before the allergic reaction develops. They used birch pollen allergen (Bet v 1) exposure and took a systems biology approach to analysis. Their findings are reported in Allergy and Journal of Allergy and Clinical Immunology.
The teams observed that Bet v 1 binds to, enters, and travels through conjunctival and nasal epithelium of allergic patients but not of healthy subjects within one minute after exposure. An allergic reaction developed when the allergen reached mast cells under the basement membrane.
Looking at samples taken from allergic patients, the researchers found that during spring, Bet v 1 changed the expression of hundreds of genes of the nasal epithelium compared to samples taken during winter. They explain that several of these genes were connected with protein transport and regulation of cytoskeleton.
On the other hand, even though there was a change in gene expression in healthy controls exposed to pollen during winter and spring, many of these genes were related to the function of the immune response.
“We were able to describe a mechanism whereby birch pollen allergen Bet v 1 travels through the epithelium of allergic patients but not of healthy subjects,” explains professor Risto Renkonen of the Haartman Institute, University of Helsinki.