BackgroundBradykinin (BK) and its biologically active metabolite des-Arg9 bradykinin (DABK) play a pivotal role in inflammation. Since chorioamnionitis is the leading cause of preterm birth and prostaglandin E2 (PGE2) derived from the amnion is key to labor initiation, we investigated if bradykinin peptides are part of the regulatory network of PGE2 synthesis in human amnion at parturition.MethodsHuman amnion tissue was obtained from term and preterm birth for the study of the changes of the bradykinin system at parturition. Cultured primary human amnion fibroblasts, the major source of PGE2, were used to study the effects of bradykinin peptides on PTGS2 expression and PGE2 production as well as the effects of infection mediators on bradykinin receptors.ResultsBradykinin peptides and their receptors BDKRB1 and BDKRB2 were present in human amnion, and their abundance increased in term and preterm labor. However, transcripts of the genes encoding the bradykinin precursor and its proteolytic cleavage enzymes were hardly detectable in human amnion despite the increased abundance of bradykinin peptides in term and preterm labor, suggesting that there is an alternative source of bradykinin peptides for human amnion and their actions are enhanced in human amnion at parturition. In-vitro studies in cultured human amnion fibroblasts showed that both BK and DABK increased the expression of prostaglandin-endoperoxide synthase 2 (PTGS2), the rate-limiting enzyme in prostaglandin synthesis, and subsequent PGE2 production. These effects of BK and DABK were mediated through BDKRB2 and BDKRB1 receptors, respectively, with subsequent activation of the p38 and ERK1/2 pathways. Moreover, lipopolysaccharide (LPS) and serum amyloid A1 (SAA1), the important mediators of infectious inflammation, induced the expression of both BDKRB1 and BDKRB2 through toll-like receptor 4 (TLR4). Induction of BDKRB1 and BDKRB2 expression by LPS and SAA1 enhanced BK- or DABK-induced PTGS2 expression and PGE2 production in human amnion fibroblasts.ConclusionsThis study demonstrated for the first time that the human amnion is a target tissue of bradykinin peptides and the bradykinin system may be part of the regulatory network of PTGS2 expression and PGE2 production in human amnion fibroblasts at both term and preterm birth, which may be enhanced by infection.

Background Enhancer of zeste homolog 2 (EZH2)-mediated histone 3 lysine 27 trimethylation (H3K27me3) is a transcription silencing mark, which is indispensable for cell lineage specification at the early blastocyst stage. This epigenetic repression is maintained in placental cytotrophoblasts but is lifted when cytotrophoblasts differentiate into syncytiotrophoblasts. However, the physiological impact of this lift remains elusive. Here, we investigated whether lifting EZH2-mediated H3K27me3 during syncytialization upregulates the expression of a short secretory isoform of a disintegrin and metalloprotease 12 (ADAM12-S), a well-recognized placenta-derived protease that cleaves insulin-like growth factor binding protein 3 to increase insulin-like growth factor (IGF) bioavailability for the stimulation of fetoplacental growth. The transcription factor and the upstream signal involved were also explored. Methods Human placenta tissue and cultured primary human placental cytotrophoblasts were utilized to investigate the role of EZH2-mediated H3K27me3 in ADAM12-S expression and the associated transcription factor and upstream signal during syncytialization. A mouse model was used to examine whether inhibition of EZH2-mediated H3K27me3 regulates placental ADAM12-S expression and fetoplacental growth. Results EZH2 and ADAM12 are distributed primarily in villous cytotrophoblasts and syncytiotrophoblasts, respectively. Increased ADAM12-S expression, decreased EZH2 expression, and decreased EZH2/H3K27me3 enrichment at the ADAM12 promoter were observed during syncytialization. Knock-down of EZH2 further increased ADAM12-S expression in trophoblasts. Syncytialization was also accompanied by increased STAT5B expression and phosphorylation as well as its enrichment at the ADAM12 promoter. Knock-down of STAT5B attenuated ADAM12-S expression during syncytialization. Epidermal growth factor (EGF) was capable of inducing ADAM12-S expression via stimulation of STAT5B expression and phosphorylation during syncytialization. Mouse studies revealed that administration of an EZH2 inhibitor significantly increased ADAM12-S levels in maternal blood and fetoplacental weights along with decreased H3K27me3 abundance and increased ADAM12-S expression in the placenta. Conclusions Lifting EZH2-mediated H3K27me3 increases ADAM12-S expression during syncytialization with the participation of EGF-activated STAT5B, which may lead to elevation of ADAM12-S level in maternal blood resulting in increased IGF bioavailability for the stimulation of fetoplacental growth in pregnancy. Our studies suggest that the role of EZH2-mediated H3K27me3 may switch from cell lineage specification at the early blastocyst stage to regulation of fetoplacental growth in later gestation.

Objective: To evaluate the efficacy of transvaginal cerclage for twins with cervical dilation or short cervix and to explore the indicated cervical length for transvaginal cerclage. Design: Prospective cohort study. Setting: Two tertiary hospitals in Shanghai, China. Population: A total of 177 twins with asymptomatic cervical dilation or cervical length ≤15 mm between 16 and 25 weeks. Methods: The logistic regression model and generalized estimation equation were used to compare the pregnancy outcomes between no-cerclage group and cerclage group followed by subgroup analysis of different cervical length. NNT and Kaplan‒Meier curves were used to estimate the efficacy of cerclage for twins in different groups. Main Outcome Measures: The primary outcome was gestational age at delivery and the neonatal survival rate within 3 months after birth. The secondary outcomes were the gestational latency from diagnosis to delivery and the risk of preterm birth before 26, 28, 32 and 34 weeks of gestation. Results: Compared with no-cerclage group, the gestational age at delivery (32.09±4.50 vs. 28.29±6.20 weeks, p<0.000) and the gestational latency from diagnosis to delivery (10.86 [7.14,13.86] vs. 3.00 [0.50,10.29] weeks, p<0.000) were longer in the cerclage group. The rate of neonatal survival (86.43% [223/258] vs. 47.92% [46/96], p<0.000) in the cerclage group was significantly higher. In the subgroup of twins with cervical dilation or cervical length <10 mm, twins in the cerclage group had significantly longer gestational age at delivery (31.33±4.63 vs. 23.44±4.25 weeks, p<0.001) and gestational latency from diagnosis to delivery (9.07 [6.29-13.57] vs. 0.43 [0.29-1.71] weeks, p<0.001). For twins with cervical length of 10-15mm, although the gestational latency (12 [9.14-13.86] vs. 9.93 [6.29-12.29] weeks, p=0.037) was significantly longer, there was no difference in gestational age at delivery (33.05±4.16 vs. 32.40±4.33 weeks, p=0.300) or neonatal survival rate (87.72% [100/114] vs. 80.77% [42/52], p=0.238) between the two groups. Conclusion: Cerclage was associated with improved maternal and neonatal outcomes in twins with cervical dilation or cervical length <15 mm. More evidence is needed to confirm the efficacy of transvaginal cerclage for twins with cervical length of 10 - 15 mm.