The intrauterine renin–angiotensin system: Sex‐specific effects on the prevalence of spontaneous preterm birth

Proteomic analysis of amniotic fluid to identify potential targets predicting preterm delivery

Preterm delivery is a common complication of pregnancy which leads to significant neonatal mortality and morbidity. Identifying predictive markers linked to spontaneous preterm delivery (SPTD) is important for effective treatment and prevention of PTD. To explore potential biomarkers related to SPTD, we performed proteomics analysis in amniotic fluid (AF). In total, we enrolled 30 pregnant women with singleton gestation who underwent clinically indicated amniocentesis at 15-24 weeks of gestation. LC-MS analysis was used to analyze the AF samples of 10 women with SPTD < 34 weeks after cervix cerclage (Preterm group), 10 women with term delivery (TD) ≥ 34 weeks after cervix cerclage (Term group), and 10 women who delivered at term (Normal group). ELISA validation was performed for candidate proteins in a second independent cohort. As a result, we identified 44 differentially expressed proteins (DEPs, P < 0.05) via proteomic analysis, and based on that, 9 primary pathways were also determined in SPTD. Results of the ELISA assay confirmed that the increased concentration of Serpin A1, decreased concentrations of Renin and IGFBP4 were significantly associated with SPTD at ≤34 weeks.

The Association Between Isolated Maternal Hypothyroxinemia in Early Pregnancy and Preterm Birth

Background: The association between isolated maternal hypothyroxinemia (IMH) during pregnancy and preterm birth (PTB), especially for subtypes of PTB, is unclear. This study aimed at determining the association between IMH diagnosed in early pregnancy and PTB, with further investigation into various subtypes of PTB. Methods: This study included 41,911 pregnant women (963 with IMH and 40,948 euthyroid women) who underwent first-trimester prenatal screening at the International Peace Maternity and Child Health Hospital (IPMCH) in Shanghai, China between January 2013 and December 2016. PTB was defined as birth before 37 weeks of gestation. PTB was further classified into three clinically relevant groups to investigate the clinical heterogeneity of PTB: (a) preterm birth with premature rupture of membranes (PROM-PTB); (b) spontaneous preterm birth with intact membranes (S-PTB); and (c) medically-induced preterm birth (MI-PTB). The overall and sex-specific effect of IMH on PTB and various subtypes of PTB were estimated by using logistic regression in crude and adjusted models. Results: Pregnant women with IMH had an increased risk of PTB (odds ratio [OR]: 1.32 [95% confidence interval; CI: 1.02-1.70], p = 0.03) compared with women with euthyroid function. The increased risk of PTB is mainly driven by S-PTB (OR: 1.57 [CI: 1.11-2.24], p = 0.01), while women with early pregnancy IMH had no statistically significant increased risk of PROM-PTB and MI-PTB. The effect of IMH on PTB was modified by fetal sex (p-values for interaction = 0.04). More prominent effects were observed in women carrying a female fetus, while no statistically significant effects were found in women carrying a male fetus. Conclusions: This study revealed that pregnant women with IMH in early pregnancy have a higher risk of PTB compared with euthyroid women. The effect of IMH on PTB is mainly driven by S-PTB and is modified by fetal sex.

Genetic Association of Angiotensin-Converting Enzyme (ACE) Gene I/D Polymorphism with Preterm Birth in Korean Women: Case-Control Study and Meta-Analysis

BACKGROUND AND OBJECTIVES

The ACE gene encodes the angiotensin-converting enzyme (ACE), a component of the renin-angiotensin system. Increased ACE activity may cause abnormal regulation of placental circulation and angiogenesis, resulting in adverse pregnancy outcomes. Previous studies have reported that the insertion/deletion (I/D) polymorphism of the ACE gene is associated with the development of preterm birth (PTB). However, results of the association between ACE gene I/D and PTB are inconsistent in various populations. Therefore, we performed a case-control study and a meta-analysis to evaluate the association between ACE I/D polymorphism and PTB. Materials and Methods: We analyzed a total of 254 subjects (111 patients with PTB and 143 women at ≥38 weeks gestation) for the case-control study. For the meta-analysis, we searched Google Scholar, PubMed, and NCBI databases with the terms "ACE," "angiotensin-converting enzyme," "preterm birth," "preterm delivery," and their combinations. Results: Our results of the case-control study indicated that ACE I/D polymorphism is significantly associated with PTBs in the overdominant genetic model (odds ratio (OR) 0.57, 95% confidence interval (CI) 0.347-0.949, p = 0.029) and that the ID genotype of ACE I/D polymorphism has a protective effect for PTB (OR 0.57, 95% CI 0.333-0.986, p = 0.043). Similarly, the meta-analysis showed that the OR for the ACE gene ID genotype was 0.66 (95% CI 0.490-0.900, p < 0.01). Conclusion: The ACE gene ID genotype has a significant association with PTB and is a protective factor for PTB. A larger sample set and functional studies are required to further elucidate of our findings.

A proposed mechanism for the Berecek phenomenon with implications for cardiovascular reprogramming

Berecek et al reported in the 1990s that when spontaneously hypertensive rat (SHR) mating pairs were treated with captopril and the resulting pups were continued on the drug for 2 months followed by drug discontinuation, the pups did not develop full blown hypertension, and the cardiovascular structural changes associated with hypertension in SHR were mitigated. The offspring of the pups also displayed diminished hypertension and structural changes, suggesting that the drug therapy produced a heritable amelioration of the SHR phenotype. This observation is reviewed. The link between cellular renin angiotensin systems and epigenetic histone modification is explored, and a mechanism responsible for the observation is proposed. In any case, the observations of Berecek are sufficiently intriguing and biologically important to merit re-exploration and definitive explanation. Equally important is determining the role of renin angiotensin systems in epigenetic modification.