Plasma interleukin‐18 (IL‐18) levels are correlated with antioxidant vitamin coenzyme Q 10 in preeclampsia

Objective. Alteration of cytokines level and oxidative stress are both associated with preeclampsia (PE). We have investigated if IL‐6 and IL‐18 levels were related to coenzyme Q 10 (CoQ 10 ), an antioxidant and a marker of oxidative stress in the plasma from normotensive and preeclamptic pregnancies. Design. IL‐6 and IL‐18 levels were determined by enzyme‐linked immunosorbent assays in plasmas from preeclamptic ( n = 29) and normotensive pregnancies ( n = 30). The concentrations of CoQ 10 in the different redox forms were measured in plasma using liquid chromatography coupled to electrochemical detection. Data were analyzed using the Wilcoxon Rank‐Sum test and correlations were obtained by the Spearman's Rho test. Main outcome measures. IL‐6 concentrations were 2.8‐fold higher in preeclamptic plasmas than in controls ( p = 0.0006), and IL‐18 concentrations were found significantly lower in preeclamptic samples than in controls ( p = 0.007). No correlation was found between IL‐18 or IL‐6 and antioxidant vitamin CoQ 10 in plasmas from normotensive pregnant women. However, in PE, IL‐18 level was positively correlated with the reduced form of CoQ 10 ( r = 0.3680, p = 0.0495). Conclusion. This is the first demonstration that IL‐18 is potentially linked to oxidative stress in PE, since its level correlates with the concentration of the powerful antioxidant CoQ 10 . These results also associate the immune system with the oxidant/antioxidant imbalance observed in PE.