Correlation of angiopoietin-2 and angiopoietin-2 receptor expressions in serum and placenta with preeclampsia

Abstract

To investigate the correlation of the expressions of angiopoietin-2 (Ang-2) and angiopoietin-2 receptor (Tie-2) in serum and placenta with preeclampsia. From May 2009 to April 2010, 62 women with preeclampsia who delivered in Affiliated Hospital of Qingdao University Medical College were recruited in the study, including 30 women with moderate preeclampsia (MPE group) and 32 women with severe preeclampsia (SPE group). Another 30 healthy pregnant women were taken as control group. ELISA was used to measure the serum Ang-2 in these women. Semiquantitative reverse transcription (RT)-PCR was used to investigate the expressions of Ang-2 mRNA and Tie-2 mRNA in placenta. Western blot was used to determine the expression of Ang-2 protein in placenta. (1) The serum concentrations of Ang-2 in MPE group and SPE group were (5.4 ± 1.8) µg/L and (5.1 ± 1.7) µg/L, respectively. Both were significantly lower than that in control group (16.2 ± 4.5) µg/L (P < 0.01). There was no significant difference between MPE group and SPE group (P > 0.05). (2) The expressions of Ang-2 mRNA in placenta of MPE group (2.1 ± 0.7) and SPE group (2.0 ± 0.6) were both significantly lower than that of control group (5.8 ± 0.8; P < 0.01). But there was no significant difference in Ang-2 mRNA expression between MPE group and SPE group (P > 0.05). (3) No significant difference was found in the expressions of Tie-2 mRNA in placenta among MPE group (1.33 ± 0.04), SPE group (1.35 ± 0.05) and control group (1.34 ± 0.04; P > 0.05). (4) The expressions of Ang-2 protein in placenta of MPE group (2.0 ± 0.8) and SPE group (2.0 ± 0.8) were both significantly lower than that of control group (5.7 ± 0.9; P < 0.01), while no significant difference was found between MPE group and SPE group (P > 0.05). (5) In MPE group and SPE group, the serum concentrations of Ang-2 were positively correlated with the levels of Ang-2 mRNA and Ang-2 protein in placenta (r = 0.651, 0.627; P < 0.01). Decreased expressions of Ang-2 mRNA and Ang-2 protein in placenta reduced serum concentration of Ang-2. Low expression of Ang-2 may be involved in the pathophysiological process of preeclampsia by affecting the formation of placenta in early pregnancy.