Asthma associated to rhinitis.

A large amount of data show that AR and asthma are associated both epidemiologically and clinically, introducing the definition of “united airway disease”. The mechanisms underlying such association were initially suggested to start from the nose, including the loss of the protective and homeostatic effects of nasal function, the activation of a naso-bronchial reflex and the spread of allergic inflammation from the nose to the lower airways. Later, other factors such as microbial stimuli and systemic inflammatory mechanisms, involving bloodstream and bone marrow, were advocated. The advance in knowledge made it clear that the link between asthma and AR is multifactorial, with particular importance for inflammatory cells and especially eosinophils. By the model of nasal challenge, important immunological responses were revealed, with particular importance for the increased expression of adhesion molecules (ICAM-1, VCAM-1 and E-selectin) and of cytokines such as interleukin (IL)-13, that was accompanied by a rise of eosinophils in blood and developement of bronchial hyper-responsiveness. The occurrence in AR of a concomitant sinusitis is frequently associated with worse asthma outcomes, as assessed by a lower pulmonary function, increased asthma symptoms and poorer quality-of-life compared to patients with asthma alone.