Peripheral RAGE (Receptor for Advanced Glycation Endproducts)-ligands in normal pregnancy and preeclampsia: novel markers of inflammatory response

Inflammatory response in preeclampsia (PE) is a key feature in its pathophysiology. Advanced Glycation Endproducts (AGEs), receptors for AGEs (RAGE), and RAGE ligands are involved in systemic inflammation in various pathological conditions. In this study, we measured serum RAGE ligands in normal pregnancy controls and PE patients. Levels of Carboxymethyl Lysine (CML), HMGB1 and S100A12/EN-RAGE were measured in thirty-three normal pregnant women 3 times at 10–12 (1st measurement), 28 (2nd measurement), and 36 (3rd measurement) weeks during gestation for paired analysis. We also measured those in serum samples from 17 severe PE patients at admission using ELISA. Early onset (EO, <32 weeks) and late onset (LO, ≥32 weeks) PE patients were compared with the 2nd and 3rd measurements of normal controls, respectively. CML and HMGB1 did not change during normal pregnancy. However, S100A12/EN-RAGE decreased from the 1st to 2nd measurement (P < 0.0001). Across all PE patients, serum CML was unaltered, while HMGB1 significantly increased compared to 2nd (P = 0.0002) and 3rd (P < 0.0001) measurement as well as individually compared to both EO (P = 0.018) and LO groups (P = 0.0001). S100A12 in all PE patients increased over 2nd (P = 0.0015) and 3rd (P = 0.0002) measurements, although only LO was significantly increased compared to the 3rd measurement (P = 0.0005). Our data suggest that patterns of serum RAGE ligand concentration indicate different inflammatory pathways in normal pregnancy, EO-PE, and LO-PE.