Placental expression of lipoprotein lipase and endothelial lipase in women with severe preeclampsia

Objective To investigate the effect of abnormal lipid metabolism in the pathogenesis of preeclampsia.Methods Thirty women with severe preeclampsia who delivered by cesarean section in the International Peace Maternity & Child Health Hospital from November 1,2011 to June 30,2012,were included as the study group.Thirty normal pregnant women delivered during the same period by cesarean section were included as the control group.The mRNA levels of lipoprotein lipase (LPL) and endothelial lipase (EL) in the placentas were quantified by real-time polymerase chain reaction.The expression of LPL/EL protein was detected by Western-blot assay and the distribution on the placenta was determined by immunohistochemical staining.The maternal serum level of lipid markers was detected by automatic biochemical analyzer.Difference between the two groups was compared with t-test or rank-sum test.Results (1) The triglyceride (TG) concentration [(3.35±0.80) mmol/L vs (2.75± 0.92) mmol/L,t =3.082,P=0.003] and atherosclerosis index (AI) (2.76±0.46 vs 2.47±0.34,t=3.066,P=0.003) increased in the study group compared with the control group,while the concentration of high-density lipoprotein-cholestrol (HDL-c) decreased[(1.64 ± 0.34) mmol/L vs (1.85 ± 0.22) mmol/L,t=-3.157,P =0.003].(2) The median level of LPL mRNA expression in placenta of the study group was higher than that of the control [1.26 (0.46-1.58) vs 0.52 (0.34-0.84),Z=-2.587,P=0.010],whereas the expression of EL mRNA was lower [0.65 (0.48-0.76) vs 1.32 (0.94-1.62),Z=-4.154,P=0.000].(3) Immunohistochemical analysis showed that the placenta EL and LPL located in cytoplasm of syncytiotrophoblast cells at the materno-placental interface and of endothelial cells at the feto-placental interface.(4) Compared with the control group,the median level of LPL protein expression in placenta inthe study group increased [0.68(0.46-0.83) vs 0.31(0.15-0.55),Z=3.335,P=0.001],and the expression of EL protein decreased [0.13 (0.11 0.16) vs 0.70(0.56 0.81),Z=-5.711,P=0.000].The expression of LPL protein was negatively correlated with that of EL protein (r=-0.501,P=0.000).Conclusions Abnormal lipid metabolism contributes to the pathogenesis of severe preeclampsia. Key words: Pre-eclampsia;  Lipoprotein lipase;  Endothelial lipase;  Placenta