Rhinosinusitis and the lower airways.

The interaction between upper and lower airway disease has been recognized for centuries, with recent studies showing a direct link between upper and airway inflammation in allergic patients. The mechanisms underlying the interaction between nasal and bronchial inflammation have primarily been studied in allergic disease, showing systemic immune activation after allergen inhalation, induction of inflammation at a distance, and a negative impact of nasal inflammation on bronchial homeostasis. Therefore, allergic rhinitis and asthma are considered part of the global airway allergy syndrome. Besides allergy, other inflammatory conditions such as the common cold, acute rhinosinusitis, and chronic rhinosinusitis are associated with lower airway disease. Chronic sinus disease with or without nasal polyps are frequently found in patients with asthma and chronic obstructive pulmonary disease with improvement of bronchial symptoms and respiratory function by adequate medical and surgical therapy for rhinosinusitis. The resolution of sinonasal inflammation and hence sinonasal functions by medical or surgical treatment is considered responsible for the beneficial effect of treatment on bronchial disease. This article aims at providing a comprehensive overview of the current knowledge on the interaction between common cold, acute and chronic rhinosinusitis, and lower airway biology.