Increased tissue factor expression and promoter hypomethylation in preeclampsia placentas in a Chinese population.

OBJECTIVES: To explore the relationship between expression of tissue factor and its methylation levels in the placentas of preeclampsia among Chinese Han population.

METHODS: In this study, we explored gene manifestation or expression of tissue factor, and evaluated methylation levels of tissue factor promoter areas in 16 clinical preeclampsia placentas as well as 16 paired normal pregnancy placentas from the Chinese Han population. Real-time PCR, immunohistochemistry, Western blotting, and methylation-specific PCR were conducted.

RESULTS: Expression of tissue factor protein in the preeclampsia group was 0.857±0.043, which was considerably elevated over that in the control group (0.248±0.035) (P<0.05). Expression of tissue factor was elevated in mRNA as well as in protein quantities in preeclampsia placentas, compared with the control group (1.45±0.42vs. 0.25±0.28, P<0.05). Immunohistochemical staining for tissue factor showed positive within syncytio-cytotrophoblast layers, and there was additional scattered staining in the preeclampsia group. Methylation-specific PCR showed that methylation levels of tissue factor promoter were considerably reduced in preeclamptic placentas (0.928±0.148), in comparison with control group (0.187±0.112, P<0.05).

CONCLUSIONS: Tissue factor is expected to participate in preeclampsia etiology through methylation regulation.