Abstract
Oxidative stress is caused by excess reactive oxygen species (ROS) and leads to cell injury, which is involved in many diseases including connective tissue diseases (CTDs) such as systemic lupus erythematosus (SLE) or systemic sclerosis (SSc). In environments of tissue hypoxia or ischemia like lung tissue in patients with pulmonary arterial hypertension (PAH), ROS were produced and able to deteriorate PAH in several ways. To clarify the participation of oxidative stress in the pathogenesis of connective tissue diseases especially with regard to complication of PAH, plasma 8-isoprostane and serum total ROS (i.e., total free radical levels derived from reactive oxygen species) levels were measured in patients with CTDs (SLE, SSc or mixed connective tissue diseases (MCTD)) and healthy controls. Plasma 8-isoprostane levels were not related to any diseases, especially not to SSc or complication of PAH. Total ROS was associated with patient age or complication of PAH. Furthermore, in CTD patients with PAH, total ROS levels were significantly correlated with serum brain natriuretic peptide (BNP) levels or estimated systolic pulmonary arterial pressures by Doppler echocardiogram. These results not only confirmed that oxidative stress played a role in the pathogenesis of CTDs including PAH but also indicate that measurement of plasma ROS can be effectual for detection of complication of PAH in patients with CTDs.
