Increased alveolar nitric oxide in early systemic sclerosis.

OBJECTIVES

Assessment of inflammatory activity in interstitial lung disease of systemic sclerosis (SSc) is difficult. Nitric oxide (NO) has gained attention in the pathogenesis of SSc. The aim of the study was to investigate alveolar NO concentration (CA(NO)) in SSc patients with short disease duration and to relate CA(NO) to radiologic findings.

METHODS

In a prospective study, 34 consecutive patients with disease duration of less than 2 years from onset of first non-Raynaud symptom and 26 healthy controls were enrolled. Exhaled NO was measured and CA(NO) was calculated. CA(NO) levels were related to the radiologic extent of pulmonary fibrosis measured as the extent of traction bronchiectasis within areas of ground glass opacities and reticulations.

RESULTS

CA(NO) levels were increased in patients with early SSc compared to healthy controls (3.52 (2.94-4.09) versus 2.08 (1.6-2.6); p<0.001). Both SSc patients with SSc-ILD (3.56 (3.04-4.73), p<0.001) and SSc patients without SSc-ILD (2.98 (2.68-3.98), p<0.01) had higher CA(NO) levels compared with healthy controls (2.08 (1.6-2.6)). CA(NO) levels did not differ between SSc patients without SSc-ILD and SSc patients with SSC-ILD. CA(NO) levels did not correlate to the extent of pulmonary fibrosis but were associated with the extent of ground glass opacities (rs=0.37, p<0.05) and reticulations (rs=0.37, p<0.05) on HRCT. CA(NO) levels were not correlated to lung function tests.

CONCLUSIONS

In patients with early SSc, alveolar NO is increased and may precede radiological changes of SSc-ILD. CA(NO) may therefore be a marker of early lung involvement.