Systemic oxidative stress in patients with pulmonary sarcoidosis

Abstract

Background A local redox imbalance has been reported in pulmonary sarcoidosis. However, so far no study has described a systemic redox imbalance in this context. The aim of the present study was to evaluate the systemic oxidative stress in patients with sarcoidosis and determine its relationship to treatment and indices of disease severity. Methods 35 patients with histologically proven pulmonary sarcoidosis and 13 healthy volunteers were included in the study. All patients were studied during a stable phase of their disease. Systemic oxidative stress was quantified in serum with the use of a commercially available spectrophotometric method (D-ROM test) which determines overall oxidative stress, by measuring total hydroperoxides. Oxidative stress was expressed in conventional units, i.e. Carratelli Units (UCarr), where 1 UCarr corresponds to 0.8 mg/L H 2O 2. Results Serum oxidative stress levels were significantly higher in patients with sarcoidosis compared to those of normal subjects (390 ± 25 vs 300 ± 18 UCarr respectively, p = 0.04). Patients not receiving systemic corticosteroids had higher levels of oxidative stress compared to steroid-treated patients (461.5 ± 38 vs 315 ± 20, p < 0.01) and compared to controls (461.5 ± 38 vs 300 ± 18 UCarr, p < 0.01). Oxidative stress did not correlate with diffusion lung capacity (DLCO), partial arterial oxygen tension (PaO 2), MRC dyspnoea scale or chest X-ray stage. Conclusions Systemic oxidative stress is increased in patients with stable pulmonary sarcoidosis who do not receive systemic corticosteroids. This finding suggests a sustained oxidative burden even when clinical, functional and radiological criteria indicate disease stability.