ObjectiveTo explore the methylation profile and protein expression of TNFAIP8 in both the preeclampsia placenta and peripheral blood.MethodsThe placental tissues of early-onset preeclampsia(EOPE), late-onset preeclampsia(LOPE)and normal pregnant group(NP)were tested by Illumina Human 450K methylation beadchip.Differences in TNFAIP8 methylation profile among three groups were verified by pyrosequencing.The expression levels of TNFAIP8 mRNA and protein expression were examined by RT-PCR and Western-blot analysis.ResultsBoth the methylation beadchip analysis and pyrosequencing showed that TNFAIP8 hypomethylation in EOPE group was significantly different compared with LOPE group or NP group(P<0.05).However, there was no significant difference between LOPE group and NP group(P>0.05).The three groups have statistically significant difference in TNFAIP8 mRNA and protein expression(P<0.05).ConclusionsSignificant hypomethylation of TNFAIP8 occurs in placenta of early-onset preeclampsia.NFAIP8 mRNA and protein overexpression are probably associated with preeclampsia pathogenesis.