Lectin pathway proteins of the complement system in normotensive pregnancy and pre-eclampsia

The lectin pathway of the complement system may be involved in the pathogenesis of pre-eclampsia. We aimed to investigate changes in serum concentrations of a broad range of lectin pathway proteins during normal pregnancy and their association with pre-eclampsia, placental infarctions and intrauterine growth restriction (IUGR).

We included 51 women with normotensive pregnancies and 54 women with pregnancies complicated by pre-eclampsia. Blood samples were obtained at gestational weeks 16, 33, 37, and after delivery for the normotensive pregnant women and before and after delivery for women with pre-eclampsia. Mannose-binding lectin (MBL), H- and M-ficolin, collectin liver-1 (CL-L1), MBL-associated serine protease (MASP)-1, MASP-2 and MASP-3 and MBL-associated proteins of 19 (MAp19) and 44 (MAp44) kDa were analysed. Clinical information was obtained from medical records. The placentae were examined by two experienced perinatal pathologists.

Lectin pathway protein concentrations generally increased during normal pregnancy and decreased after delivery in both normotensive pregnant women and women with pre-eclampsia. Exceptions were MASP-3 which increased after delivery in both groups (P < 0.0001) and H-ficolin which increased after delivery in pre-eclampsia (P < 0.0001). H-ficolin (P < 0.0001), M-ficolin (P = 0.005) and MASP-3 (P = 0.03) concentrations were lower in women with pre-eclampsia than in normotensive pregnant women. Low MASP-3 concentrations were associated with placental infarction (P = 0.03) and IUGR (P = 0.04). Low H-ficolin concentrations were associated with IUGR (P < 0.01).

In general, lectin pathway protein serum concentrations increased during normal pregnancy. H-ficolin and MASP-3 may be involved in the pathophysiology of pre-eclampsia and IUGR and could be potential future pre-eclampsia biomarkers.