Increased urinary F2-isoprostanes in systemic sclerosis, but not in primary Raynaud's phenomenon: effect of cold exposure.

Objective: F2-isoprostanes are free radical-dependent arachidonic acid metabolites that are used as clinical markers of lipid peroxidation in systemic sclerosis (SSc) and other microvascular diseases. The objectives of this study were to determine whether the basal urinary levels of F2-isoprostane in SSc patients differ from those in patients with primary Raynaud's phenomenon (RP) and to investigate whether F2-isoprostane formation correlates with the cutaneous microvascular perfusion decrease following cold exposure in SSc patients, patients with primary RP, and healthy controls.

Methods: Eleven women with RP secondary to SSc, 11 women with primary RP, and 11 healthy women were exposed to decreasing room temperature, from 25 degrees C to 15 degrees C, for 40 minutes. Urine samples were obtained before and after the test for gas chromatography/electronic impact mass spectrometry quantification of 15-F(2t)-isoprostane (15-F(2t)-IsoP; also called isoprostaglandin F(2alpha) type III). Cutaneous blood flow was monitored using a laser Doppler perfusion imager.

Results: The mean +/- SEM urinary 15-F(2t)-IsoP levels at baseline in SSc patients (178 +/- 32 pmoles/mmole of creatinine) were 1.9 times higher than those in healthy controls (95 +/- 11 pmoles/mmole of creatinine) and 1.7 times higher than those in patients with primary RP (107 +/- 19 pmoles/mmole of creatinine) (P < 0.05 for controls and patients with primary RP versus SSc patients). No significant correlation was found between basal urinary 15-F(2t)-IsoP levels and the temperature or cutaneous blood flow decrease in response to the whole-body cooling. Furthermore, the 15-F(2t)-IsoP response to the cooling test was not correlated with the cutaneous blood flow decrease.

Conclusion: Lipid peroxidation is increased in SSc patients, but not in patients with primary RP. Cold exposure leads to a significant but small increase in 15-F(2t)-IsoP levels that is independent of the cutaneous blood flow decrease. F2-isoprostane quantification may be an interesting pharmacologic tool for monitoring responses to antioxidant treatment in SSc patients.