Objective: To study expression and activation of p38 mitogen activated protein kinase (MAPK) in vascular endothelial cells dysfunction in preeclampsia.
Methods: From Sept. 2009 to Mar. 2010, 54 pregnant women underwent deliveries in the First Affiliated Hospital of Chongqing Medical University were enrolled in this study, including 20 patients in mild preeclampsia group, 16 patients in severe preeclampsia group and 18 women with term cesarean section without perinatal complications as control group. Placental endothelial cells were labeled by CD₃₄ to assay microvessel density (MVD) of each group. Immunohistochemical SP and western blot were used to detect localization and expression of p-p38 MAPK protein, respectively. The levels of sera soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng) were measured by ELISA.
Results: (1) The MVD of placenta were 103 ± 3 in control group, 81 ± 5 in mild preeclampsia group and 63 ± 4 in severe group, respectively, which showed statistical difference among each group (P < 0.05). (2) The expression of p38 MAPK protein were 0.84 ± 0.05 in control group, 0.90 ± 0.14 in mild group and 0.86 ± 0.18 in severe group, which did not reach remarkable difference among each group (P > 0.05). The expression of p-p38 MAPK protein were 0.13 ± 0.05 in control group, 0.59 ± 0.12 in mild group and 1.16 ± 0.18 in severe group, which show statistical difference among each group (P < 0.05). (3) The localization of p-p38 was in trophoblast, endothelial cells and a few stromal cells in placenta. (4) The level of sFlt-1 and sEng: (1) The concentration of sFlt-1 and sEng were (5.2 ± 0.3) and (10.9 ± 0.4) µg/L in control group, (12.5 ± 1.2) and (20.4 ± 5.3) µg/L in mild group and (19.3 ± 3.0) and (29.5 ± 3.7) µg/L in severe group. When drawing paired comparison in those groups, the differences showed statistical difference (P < 0.05). (2) There were positive correlations between p-p38 MAPK protein levels and the concentrations of serum sFlt-1, sEng in preeclampsia groups (r = 0.68, P < 0.05; r = 0.87, P < 0.05).
Conclusions: The remarkable activation of the p38 MAPK in the placenta of patients with preeclampsia induced the increased levels of sFlt-l and sEng in maternal serum, which confer the injury of vascular endothelial cells that caused the significant decline of MVD in placentas. p38 MAPK signaling might be one of the key pathways in vascular endothelial cell dysfunction in preeclampsia.