Allergic rhinitis: past, present and the future.

Allergic rhinitis represents a global health issue affecting between 10% to 25% of the world population, with increasing prevalence over the last decade. Although often trivialized by patients and doctors, allergic rhinitis is a significant cause of morbidity, in addition to its substantial economic impact. While allergic rhinitis is an inflammatory disorder of the upper airways, inflammation alone is insufficient to explain the chronic nature of the disease. An exciting concept which has recently emerged in asthma concerns the role of the bronchial epithelium as a key regulator of airway inflammatory and remodelling responses in asthma. It has been shown by our group that the disruption and alteration in the function of the lower airway epithelium in asthma leads to the generation of a variety of stimuli that lead to the restructuring of the airway wall. This raises interesting questions regarding a similar role for the upper airway epithelium in allergic rhinitis. This review aims to interpret past and current research into allergic rhinitis, and to address specific areas where future research is warranted, particularly in relation to the possibility of an altered upper airway epithelial phenotype in allergic rhinitis.