Correlation between the expression of high mobility group box 1 and receptor for advanced glycation end products and the onset of pre-eclampsia

Abstract

To evaluate different expressions of high mobility group box 1 (HMGB1) and receptor for advanced glycation end products (RAGE) in placentas and their relationship with pre-eclampsia. Fifteen early-onset pre-eclamptic women (early-onset pre-eclampsia group), 22 late-onset pre-eclamptic women (late-onset pre-eclampsia group) and 12 normotensive women (control group) in the third trimester were recruited at the Shengjing Hospital of China Medical University from March 2006 to March 2007. The localization and levels of HMGB1 and RAGE in placentas of the three groups were detected by the strept avidin biotin-peroxidase method. (1) Immunoreactivities to HMGB1: positive immunostaining for HMGB1 was observed in trophoblast, macrophages, decidual cells, vascular muscle cells, endothelial cells and placental mesenchymal cells in the placentas from the pre-eclamptic women, while a low level of immunoreactivities was observed in the placentas from healthy pregnancies; the staining was observed within both the nuclei and the cytoplasm, mainly in the cytoplasm. The cytotrophoblast, especially the nuclei was extensively positive for HMGB1 in early-onset pre-eclampsia. (2) Immunoreactivities to RAGE: positive immunostaining for HMGB1 was observed in syncytiotrophoblast, macrophages and endothelial cells in the placentas from the preeclamptic women, while a low level of immunoreactivities was observed in the placentas from healthy pregnancies; the staining was in the cytoplasm and (or) cell membrane. The trophoblast was extensively positive for RAGE in early-onset pre-eclampsia. (3) Positive rate of HMGB1 expression: the expression of HMGB1 in early-onset group (73%, 11/15) and late-onset group (64%, 14/22) was significantly higher than that in normal group (17%, 2/12; P < 0.05), but no significant difference was found in early-onset group and late-onset group (P > 0.05). (4) Positive rate of RAGE expression: the expression of RAGE in early-onset group (80%, 12/15) and late-onset group (82%, 18/22) was significantly higher than that in normal group (25%, 3/12; P < 0.05), but no significant difference was found in early-onset group and late-onset group (P > 0.05). The increased expression of HMGB1 and RAGE in the placenta may play an important role in the pathogenesis of pre-eclampsia. The different locations may be associated with the occurrence of different onset types of pre-eclampsia.