Aging of intrauterine tissues in spontaneous preterm birth and preterm premature rupture of the membranes: A systematic review of the literature.

BACKGROUND: Many adverse pregnancy outcomes (APOs), including spontaneous preterm birth (PTB), are associated with placental dysfunction. Recent clinical and experimental evidences suggest that premature aging of the placenta may be involved in these events. Although placental aging is a well-known concept, the mechanisms of aging during normal pregnancy and premature aging in APOs are still unclear. This review was conducted to assess the knowledge on placental aging related biochemical changes leading to placental dysfunction in PTB and/or preterm premature rupture of membranes (pPROM). METHODS: We performed a systematic review of studies published over the last 50 years in two electronic databases (Pubmed and Embase) on placental aging and PTB or pPROM. RESULTS: The search yielded 554 citations, 30 relevant studies were selected for full-text review and three were included in the review. Only one study reported oxidative stress-related aging and degenerative changes in human placental membranes and telomere length reduction in fetal cells as part of PTB and/or pPROM mechanisms. Similarly, two animal studies reported findings of decidual senescence and referred to PTB mechanisms. CONCLUSION: Placental and fetal membrane oxidative damage and telomere reduction are linked to premature aging in PTB and pPROM but the risk factors and biomolecular pathways causing this phenomenon are not established in the literature. However, no biomarkers or clinical indicators of premature aging as a pathology of PTB and pPROM have been reported. We document major knowledge gaps and propose several areas for future research to improve our understanding of premature aging linked to placental dysfunction.

Expression profiles of fetal membrane nicotinamide adenine dinucleotide phosphate oxidases (NOX) 2 and 3 differentiates spontaneous preterm birth and pPROM pathophysiologies.

INTRODUCTION: Nicotinamide adenine dinucleotide phosphate oxidases (NOX 1-5) are enzymes that generate cellular reactive oxygen species (ROS) besides mitochondria and might be important ROS sources associated with pregnancy complications, particularly preterm premature rupture of membranes (pPROM), that has been related to ROS. OBJECTIVE: To characterize NOX enzymes expression in human fetal membranes. METHODS: Differential expression and localization of NOX isoforms in human fetal membranes collected from women with uncomplicated pregnancies at term, preterm birth (PTB) or pPROM and in vitro in normal term membranes maintained in an organ explant system stimulated with water-soluble cigarette smoke extract (wsCSE) were documented by real time PCR and immunohistochemistry. RESULTS: Fetal membranes from term deliveries, PTB and pPROM expressed NOX 2, 3 and 4 mRNAs whereas NOX 1 and 5 were not detected. NOX 2 expression was 2.3-fold higher in PTB than pPROM (p = 0.005) whereas NOX 3 was 2.2-fold higher in pPROM compared to PTB (p = 0.04). NOX 2 and 3 expressions at term mimicked pPROM and PTB, respectively. No difference in NOX 4 expression was observed among the studied groups. NOX 2, 3 and 4 were localized to both amniotic and chorionic cells. Expression of NOX 2, 3 and 4 were not significant in wsCSE-stimulated membranes compared to untreated controls. DISCUSSION/CONCLUSIONS: NOX enzymes are present in the fetal membranes and are differentially expressed in PTB and pPROM. Absence of any changes in NOXs expression after wsCSE stimulation suggests ROS generation in the membranes does not always correlate with NOX expression.

Inflammatory cytokine mRNA detection by real time PCR in chorioamniotic membranes from pregnant women with preterm premature rupture of membranes.

OBJECTIVE: To quantify the expression of interleukin (IL)-1beta, IL-6, IL-8 and tumor necrosis factor alpha (TNF-alpha) in chorioamniotic membranes of PPROM pregnant women with chorioamnionits. STUDY DESIGN: The study included 25 PPROM women in labor, 15 PPROM without labor, and 25 pregnant women in preterm labor (PTL). Chorioamniotic membranes were collected for histopathological analyses and cytokine mRNA expression quantification by real time PCR. Comparisons were performed using the Mann-Whitney, Kruskal-Wallis, Fisher's exact test or z test with significance set at p<0.05. The software employed was the SigmaStat version 3.1. RESULTS: During the study PPROM incidence was 4.6% and chorioamnionits was present in 75% of the samples. IL-1beta, IL-6, and IL-8 mRNA expression did not statistically differ among study groups. TNF-alpha mRNA expression was statistically higher in PTL. No difference in the mRNA concentration of the cytokines studied in the presence of chorioamnionitis was observed. CONCLUSION: Chorioamniotic membranes are sources of IL-1beta, IL-6, IL-8, and TNF-alpha and their mRNA concentrations in PPROM are not related to the presence of chorioamnionitis.