Search

We measured the urinary excretion of Isoprostane F2-III and Isoprostane-F2-VI, two markers of in vivo lipid peroxidation, and the circulating levels of the prothrombin fragment F1+2, a marker of thrombin generation, in 18 antiphospholipid antibodies-positive patients, in 18 antiphospholipid antibodies-negative patients with systemic lupus erythematosus, and in 20 healthy subjects. Furthermore, 12 patients positive for antiphospholipid antibodies were treated with (n = 7) or without (n = 5) antioxidant vitamins (vitamin E at 900 IU/d and vitamin C at 2,000 mg/d) for 4 weeks. Compared with antiphospholipid antibodies-negative patients, antiphospholipid antibodies-positive patients had higher urinary values of Isoprostane-F2-III (P = .0001), Isoprostane-F2-VI (P = .006), and plasma levels of the prothrombin fragment F1+2 (P= .0001). In antiphospholipid-positive patients, F1+2 significantly correlated with Isoprostane-F2-III (Rho = .56,P = .017) and Isoprostane-F2-VI (Rho = .61, P = .008). After 4 weeks of supplementation with antioxidant vitamins, we found a significant decrease in F1+2 levels (P < .005) concomitantly with a significant reduction of both Isoprostane-F2-III (P = .007) and Isoprostane-F2-VI (P < .005). No change of these variables was observed in patients not receiving antioxidant treatment. This study suggests that lipid peroxidation might contribute to the activation of clotting system in patients positive for antiphospholipid antibodies.

Clotting activation may occur in liver cirrhosis, but the pathophysiological mechanism has not been fully elucidated. Because a previous study demonstrated that lipid peroxidation is increased in cirrhosis, we analyzed whether there is a relationship between lipid peroxidation and clotting activation. Thirty cirrhotic patients (19 men and 11 women; age, 34 to 79 years) and 30 controls matched for sex and age were investigated. In all subjects, monocyte expression of tissue factor (TF) antigen and activity; plasma levels of prothrombin fragment 1+2 (F1+2), a marker of thrombin generation; and urinary excretion of Isoprostane-F2-III, a marker of lipid peroxidation, were measured. Furthermore, the above-reported variables were re-evaluated after 30 days of treatment with standard therapy (n = 5) or standard therapy plus 300 mg vitamin E twice daily (n = 9). In addition, we analyzed in vitro if vitamin E (50 μmol/L) influenced monocyte TF expression and F1+2 generation. Cirrhotic patients had higher values of Isoprostane-F2-III (P < .0001), F1+2 (P < .0001), and monocyte TF antigen (P < .0001) and activity (P < .03) than controls. Isoprostane-F2-III was significantly correlated with F1+2 (Rho = 0.85; P < .0001) and TF antigen (Rho = 0.95; P < .0001) and activity (Rho = 0.94;P < .0001). After vitamin E treatment, Isoprostane-F2-III (P = .008), F1+2 (P < .008), and monocyte TF antigen (P = .012) and activity (P = .008) significantly decreased; no changes of these variables were detected in patients not receiving vitamin E. In vitro, vitamin E significantly reduced the expression of monocyte TF antigen (−52%; P = .001) and activity (−55%; P= .003), as well as F1+2 generation (−51%; P = .025). This study shows that vitamin E reduces both lipid peroxidation and clotting activation and suggests that lipid peroxidation may be an important mediator of clotting activation in liver cirrhosis.

The mechanism leading to the formation of antiphospholipid antibodies (aPL) is still unknown. Because an in vitro study suggested that aPL may derive from pro-oxidant conditions, we sought a relationship between aPL and isoprostanes, indices of lipid peroxidation in vivo. Thirty patients with systemic lupus erythematosus have been studied. Seventeen (56.6%) were positive for aPL because they had lupus anticoagulant and/or high titer of anticardiolipin antibodies (aCL). Plasma levels of tumor necrosis factor (TNF ) and urinary excretion of two isoprostanes, 8-epi-PGF2α and IPF2α -I, free radical catalyzed oxidation products of arachidonic acid, were measured. Patients with systemic lupus erythematosus had higher urinary excretion of 8-epi-PGF2α and IPF2α -I than controls; urinary excretion of the two isoprostanes was highly correlated (Rho = 0.74, P < .0001). Urinary 8-epi-PGF2α was highly correlated with both aCL titer (Rho = 0.70, P < .0001) and TNF (Rho = 0.84, P < .0001), a measure of disease severity. Excretion of this isoprostane was also higher in those patients who exhibited aPL (P < .0001). Comparable correlations were observed with the isoprostane IPF2α -I. No difference of 8-epi-PGF2α was observed between patients with and without previous history of thrombosis. This study, showing the existence of a close association between aPL and increased in vivo lipid peroxidation, supports the hypothesis that these antibodies may result from pro-oxidative conditions and suggests that inflammation may play an important role.