Hemopexin and α₁-microglobulin heme scavengers with differential involvement in preeclampsia and fetal growth restriction

by Lina Youssef, Lena Erlandsson, Bo Åkerström, Jezid Miranda, Cristina Paules, Francesca Crovetto, Fatima Crispi, Eduard Gratacos, Stefan R. Hansson

Hemopexin and α₁-microglobulin act as scavengers to eliminate free heme-groups responsible for hemoglobin-induced oxidative stress. The present study evaluated maternal and fetal plasma concentrations of these scavengers in the different phenotypes of placenta-mediated disorders. Singleton pregnancies with normotensive fetal growth restriction [FGR] (n = 47), preeclampsia without FGR (n = 45) and preeclampsia with FGR (n = 51) were included prospectively as well as uncomplicated pregnancies (n = 49). Samples were collected at delivery and ELISA analysis was applied to measure the hemopexin and α₁-microglobulin concentrations. In maternal blood in preeclampsia with and without FGR, hemopexin was significantly lower (p = 0.003 and p<0.001, respectively) and α₁-microglobulin was significantly higher (p<0.001 in both) whereas no difference existed in normotensive FGR mothers compared to controls. In contrast, in fetal blood in growth restricted fetuses with and without preeclampsia, both hemopexin and α₁-microglobulin were significantly lower (p<0.001 and p = 0.001 for hemopexin, p = 0.016 and p = 0.013 for α₁-microglobulin, respectively) with no difference in fetuses from preeclampsia without FGR in comparison to controls. Thus, hemopexin and α₁-microglobulin present significantly altered concentrations in maternal blood in the maternal disease -preeclampsia- and in cord blood in the fetal disease -FGR-, which supports their differential role in placenta-mediated disorders in accordance with the clinical presentation of these disorders.