Increased nitric oxide in expired air in patients with Sjogren's syndrome

Nitric oxide has an important role in the regulation of airway function and can have pro-inflammatory effects. Bronchial hyperresponsiveness (BHR) and respiratory symptoms are common in patients with Sjogren's syndrome (SS), The aim of this study was to determine whether patients with SS have an inc reased amount of exhaled NO and whether this NO correlates with respiratory symptoms and BHR, Exhaled NO was measured in 18 patients with SS and 13 normal subjects on th ree different occasions with intervals of at least 3 days using a chemilumi nescence method. Airway responsiveness was assessed with methacholine provo cation, Serum levels of myeloperoxidase (MPO), human neutrophil lipocalin ( HNL), eosinophil cationic protein (ECP) and eosinophil peroxidase (EPO) wer e measured. Exhaled NO was significantly higher in patients with SS than in controls (1 47+/-82 versus 88+/-52 nL.min(-1;) mean+/-SD; p=0.041). Exhaled NO was corr elated with age (partial r=0.52, p=0.006) and serum HNL (partial r=0.46, p= 0.014). There were no significant correlations between exhaled NO and respi ratory symptoms, BHR or serum MPO, ECP or EPO, Disease duration was negativ ely associated with serum MPO (r=-0.47, p=0.043), In patients with SS, a po sitive correlation was found between symptom score and serum ECP (partial r =0.65, p=0.003) and EPO (partial r=0.62, p=0.004) and a negative correlatio n with age (partial r-0.60, p=0.005), In conclusion, elevated levels of exhaled nitric oxide in patients with Sjo gren's syndrome mere demonstrated, The mechanism underlying this increase i n exhaled nitric oxide in Sjogren's syndrome is not known.