Comparison of arginase isoform expression in patients with different subtypes of chronic rhinosinusitis.

OBJECTIVE: Although human paranasal sinuses are critical organs for nitric oxide production, little information is available regarding the role of arginase in alterations of arginine metabolism and nasal nitric oxide levels that may be informative for classifying chronic rhinosinusitis subtypes.

METHODS: The expression and localisation of arginase and nitric oxide synthase isoforms in paranasal sinus mucosa were examined, and the fractional exhaled nitric oxide was measured in chronic rhinosinusitis without nasal polyps (n=18) and chronic rhinosinusitis with nasal polyps (n = 27) patients.

RESULTS: Increased arginase-2 activities in chronic rhinosinusitis without nasal polyps patients were associated with significantly lower levels of nasal fractional exhaled nitric oxide. Chronic rhinosinusitis with nasal polyps patients showed significant NOS2 messenger RNA upregulation with concomitant higher levels of oral and nasal fractional exhaled nitric oxide.

CONCLUSION: These results indicate that fractional exhaled nitric oxide is a valid marker for differentiating chronic rhinosinusitis phenotypes based on a delicate balance between arginase and nitric oxide synthase activities in nitric oxide production.