The role of nitric oxide in chronic rhinosinusitis

Chronic rhinosinusitis is a very common medical condition that affects nasal and paranasal sinuses mucosa in both adults and children. Its pathology, however, still remains unclear and researchers focus more and more on the role of nitric oxide (NO), a free radical produced in normal conditions by the paranasal sinuses epithelium in healthy patients, in the development of this disease. NO’s role in the upper airway disease is not completely known, but it appears to act like a first-line host defence agent, maintaining the sinuses sterile due to its antiviral and bacteriostatic properties and by increasing mucociliary clearance. NO levels in the exhaled air of patients with CRS are lower than in healthy patients. One explanation for this might be the sinus obstruction that occurs in CRS because subjects with complete sinus opacification have the lowest levels. Furthermore, NO levels decrease after CRS treatments, suggesting that its measurement might help in monitoring the patient’s response to therapy. In this review, we discuss the NO synthesis in the respiratory tract, its involvement in airway pathology, its role in the pathogenesis of CRS and the current clinical uses for NO in CRS and several other airway diseases.