[A connection between allergic rhinitis and allergic asthma? The "one-airway-one-disease"-hypothesis]

The nose and the lungs are anatomically and physiologically divided which lead to separated strategies in diagnostic and therapy. The upper airways, from the nose and lungs may account for the traditional division in upper and lower airways. Nonetheless a link between upper and lower respiratory tracts has been repeatedly observed in the past decades making the current division in two separate entities an arbitrary dichotomy. Once allergic rhinitis and asthma are two manifestation of the atopic syndrome it is logical to expect that allergy is not a disease confined to specific target organ rather to a broad spectrum of clinical manifestations. This hypothesis has been supported from various observations: Both, allergic asthma and allergic rhinitis are characterized by a similar if not an identical inflammatory process in which mast cells and eosinophils appear to be the major effector cells, high comorbidity of both allergic manifestations as shown in epidemiologic studies. Both diseases are caused by the interaction of genetic susceptibility with environmental factors. In this review, the latest developments in epidemiology and pathophysiology with regard to nasobronchial interaction in allergic airway disease will be discussed.