The Role of the NLRP3 Inflammasome in the Molecular and Biochemical Mechanisms of Cervical Ripening: A Comprehensive Review.

The uterine cervix is one of the key factors involved in ensuring a proper track of gestation and labor. At the end of the gestational period, the cervix undergoes extensive changes, which can be summarized as a transformation from a non-favorable cervix to one that is soft and prone to dilation. During a process called cervical ripening, fundamental remodeling of the cervical extracellular matrix (ECM) occurs. The cervical ripening process is a derivative of many interlocking and mutually driving biochemical and molecular pathways under the strict control of mediators such as inflammatory cytokines, nitric oxide, prostaglandins, and reactive oxygen species. A thorough understanding of all these pathways and learning about possible triggering factors will allow us to develop new, better treatment algorithms and therapeutic goals that could protect women from both dysfunctional childbirth and premature birth. This review aims to present the possible role of the NLRP3 inflammasome in the cervical ripening process, emphasizing possible mechanisms of action and regulatory factors.

Quantitative cervicovaginal fetal fibronectin as a predictor of cervical ripening and induced labour duration in late-term pregnancy.

We evaluated quantitative cervicovaginal foetal-fibronectin as a predictor of cervical ripening and labour duration in late-term pregnant women with an unfavourable cervix. This was an analytical cross-sectional study wherein 152 women, with late-term pregnancy and unfavourable cervix, at 41weeks3days gestational age, had pre-induction quantitative cervicovaginal foetal-fibronectin determined using ELISA. Data were compared in nulliparas and multiparas at a significance level < 0.05. The mean age of late-term pregnant women was 30.4 ± 4.3 years. Median cervicovaginal foetal-fibronectin levels in nulliparous and multiparous women were 45.35 ng/ml and 46.93 ng/ml respectively(p = 0.289). The correlation between foetal-fibronectin levels and cervical ripening duration was poor in nulliparous(r = 0.014) and multiparous(r = 0.024) women. The Youden's foetal-fibronectin cut-off level had a sensitivity of 53.5% and specificity of 71.6% in predicting cervical ripening duration of > 12 hours in late-term pregnancy with an area under the ROC curve of 0.634. Quantitative cervicovaginal foetal-fibronectin is a poor correlate and predictor of cervical ripening and induced labour duration in late-term pregnancy.IMPACT STATEMENTWhat is already known on this subject? Cervicovaginal foetal fibronectin is useful in the prediction of preterm delivery but its role in prolonged pregnancy is unclear.What the results of this study add? Cervicovaginal foetal fibronectin is a poor correlate and predictor of cervical ripening and induced labour duration in late-term pregnancyWhat the implications are of these findings for clinical practice and/or further research? Cervicovaginal fibronectin should not be used to predict ease and success of cervical ripening and induction of labour in women with late-term pregnancy.

Impact of Oxidative Stress on Molecular Mechanisms of Cervical Ripening in Pregnant Women.

Uterine cervix is one of the essential factors in labor and maintaining the proper course of pregnancy. During the last days of gestation, the cervix undergoes extensive changes manifested by transformation from a tight and rigid to one that is soft and able to dilate. These changes can be summarized as "cervical ripening". Changes in the cervical tissue can be referred to as remodeling of the extracellular matrix. The entire process is the result of a close relationship between biochemical and molecular pathways, which is strictly controlled by inflammatory and endocrine factors. When the production of reactive oxygen species exceeds the antioxidant capacity, oxidative stress occurs. A physiologic increase of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is observed through pregnancy. ROS play important roles as second messengers in many intracellular signaling cascades contributing to the course of gestation. This review considers their involvement in the cervical ripening process, emphasizing the molecular and biochemical pathways and the clinical implications.

Signaling Pathways Regulating Human Cervical Ripening in Preterm and Term Delivery.

At the end of gestation, the cervical tissue changes profoundly. As a result of these changes, the uterine cervix becomes soft and vulnerable to dilation. The process occurring in the cervical tissue can be described as cervical ripening. The ripening is a process derivative of enzymatic breakdown and inflammatory response. Therefore, it is apparent that cervical remodeling is a derivative of the reactions mediated by multiple factors such as hormones, prostaglandins, nitric oxide, and inflammatory cytokines. However, despite the research carried out over the years, the cellular pathways responsible for regulating this process are still poorly understood. A comprehensive understanding of the entire process of cervical ripening seems crucial in the context of labor induction. Greater knowledge could provide us with the means to help women who suffer from dysfunctional labor. The overall objective of this review is to present the current understanding of cervical ripening in terms of molecular regulation and cell signaling.

Metabonomics profile analysis in inflammation-induced preterm birth and the potential role of metabolites in regulating premature cervical ripening.

BACKGROUND: Preterm birth (PTB) is the primary cause of infant morbidity and mortality. Moreover, previous studies have established that PTB is related to premature cervical ripening. However, the underlying mechanism remains to be elucidated. This study sought to identify differentially expressed metabolites and investigate their potential biological functions in PTB. METHODS: Pregnant C57BL/6 J mice were treated with either LPS or normal saline and cervical alterations before labor were detected by staining. Metabolic profiles in the plasma of PTB and control mice were examined through non-targeted metabonomics analyses, quantitative polymerase chain reaction and immunofluorescence staining were performed on human cervical smooth cells. RESULTS: The study demonstrated that the mRNA and protein levels of α-SMA, SM-22, and calponin in cervical smooth muscle cells of PTB mice were lower while OR was higher at both mRNA and protein levels compared to the CTL group. A total of 181 differentially expressed metabolites were analyzed, among them, 96 were upregulated, while 85 were downregulated in the PTB group. Differentially expressed metabolites may play a role in STAT3, RhoA, mTOR, TGF-ß, and NK-κB signaling pathways. Furthermore, when treated with taurine, the levels of α-SMA and SM-22 in human cervical smooth muscle cells were elevated, whereas that of connexin-43 was decreased. CONCLUSION: Our study highlighted the changes of metabolites in the peripheral blood changed prior to PTB and revealed that these differentially expressed metabolites might participate in the development of premature cervical ripening. Taurine was identified as an important metabolite may modulate human cervical smooth muscle cells. Our study provided new insights into the mechanism underlying premature cervical ripening in PTB.

Cervical ripening for a singleton fetus in breech prensentation at term: Comparison between mechanical and pharmaceutical methods.

Although various international professional societies currently recommend trial of vaginal delivery of term fetuses in breech presentation, the question of the method of cervical ripening, when necessary, remains open. OBJECTIVE: To compare the effectiveness of two methods of cervical ripening for delivery of a singleton fetus in breech presentation at term: a mechanical method (balloon catheter) and a pharmaceutical method (prostaglandins). STUDY DESIGN: This two-center retrospective study reviewed records from 2014 through 2019 in two French maternity units with two different cervical ripening methods for fetuses in breech presentation. The study included all women with cervical ripening for a medical indication with a live singleton fetus in breech presentation ≥ 37 weeks, with an unfavorable cervix. The group treated with a mechanical method was compared with the group receiving a pharmaceutical method. The cesarean delivery rate was the principal outcome, and maternal and neonatal morbidity the secondary outcomes. RESULTS: We included 74 women, 19 with mechanical cervical ripening, and 55 with pharmaceutical treatment. The cesarean rate was 57.9% in the balloon catheter group and 40% in the prostaglandin group (P = 0.097) (crude OR =2.06, 95% CI [0.72 - 5.94]; adjusted OR = 2.88, 95% confidence interval [0.52-15.96]), and the postpartum hemorrhage rates 21.1% and 1.8% respectively (P = 0.008). Neonatal morbidity did not differ significantly. CONCLUSION: Although the cesarean rate and neonatal morbidity and mortality did not differ significantly between these two methods of cervical ripening, our study lacked power.

Cervical biomarkers as predictors of successful induction of labour by Foley catheter.

The prediction of successful labour induction is difficult, indicating a need for a biomarker test. Little is known about the effect of Foley catheter (FC) induction on biochemical mediators in the cervix, such as the insulin-like growth factor binding protein-1 (IGFBP-1), matrix metalloproteinases (MMP) and their inhibitors (TIMP). We enrolled 35 nulliparous women with singleton pregnancies, intact amniotic membranes and cephalic presentation ≥40 gestational weeks scheduled for labour induction by FC. Serial cervical swab samples were collected at FC insertion and expulsion. The concentrations of IGFBP-1, PhIGFBP-1, MMP-8, MMP-2, MMP-9, TIMP-1 and TIMP-2 were analysed. The IGFBP-1 and phIGFBP-1 concentrations increased during the FC-induced cervical ripening. In contrast, MMP-8 and MMP-9 concentrations decreased. However, these changes did not predict the outcome of the labour induction, thus appearing not suitable for clinical use. Impact statement What is already known on this subject? During cervical ripening, various constituents interact in a complex network. Insulin-like growth factor binding protein-1 (IGFBP-1), matrix metalloproteinases (MMP) and their tissue inhibitors (TIMP) appear to play a role in cervical ripening. The mechanism of Foley catheter on cervical ripening consists of direct mechanical stretching of the cervix and lower uterine segment, and the stimulation of local secretion of endogenous prostaglandins. What do the results of this study add? This study investigated the role of cervical biochemical mediators during Foley catheter-induced cervical ripening, and their predictive value in a successful labour induction and vaginal delivery. The IGFBP-1 and phosphorylated IGFBP-1 concentrations increased, whereas MMP-8 and MMP-9 concentrations decreased during the Foley catheter-induced cervical ripening in nulliparous women. However, these changes did not predict the outcome of labour induction, thus appearing not suitable for clinical use. What are the implications of these findings for clinical practice and/or further research? Prediction of a successful labour induction is difficult, indicating a need for a biomarker test. Future studies with larger data are needed for investigating the role of these cervical biomarkers in successful labour induction, and in developing a future bedside a screening tool for clinical use.

Prostaglandin dehydrogenase is a target for successful induction of cervical ripening.

The cervix represents a formidable structural barrier for successful induction of labor. Approximately 10% of pregnancies undergo induction of cervical ripening and labor with prostaglandin (PG) E2 or PGE analogs, often requiring many hours of hospitalization and monitoring. On the other hand, preterm cervical ripening in the second trimester predicts preterm birth. The regulatory mechanisms of this paradoxical function of the cervix are unknown. Here, we show that PGE2 uses cell-specific EP2 receptor-mediated increases in Ca2+ to dephosphorylate and translocate histone deacetylase 4 (HDAC4) to the nucleus for repression of 15-hydroxy prostaglandin dehydrogenase (15-PGDH). The crucial role of 15-PGDH in cervical ripening was confirmed in vivo. Although PGE2 or 15-PGDH inhibitor alone did not alter gestational length, treatment with 15-PGDH inhibitor + PGE2 or metabolism-resistant dimethyl-PGE2 resulted in preterm cervical ripening and delivery in mice. The ability of PGE2 to selectively autoamplify its own synthesis in stromal cells by signaling transcriptional repression of 15-PGDH elucidates long sought-after molecular mechanisms that govern PG action in the cervix. This report details unique mechanisms of action in the cervix and serves as a catalyst for (i) the use of 15-PGDH inhibitors to initiate or amplify low-dose PGE2-mediated cervical ripening or (ii) EP2 receptor antagonists, HDAC4 inhibitors, and 15-PGDH activators to prevent preterm cervical ripening and preterm birth.

IGFBP-1 marker of cervical ripening and predictor of preterm birth.

Aim To establish a correlation between positive values of IGFBP-1(>10 mg/L, Actim Partus Test, APT) and premature cervical ripening in imminent preterm labor. Methods A prospective study was conducted in primary health care centers in Tuzla, Gynecology and Obstetrics Clinic of the University Clinical Centre in Tuzla and General Hospital Tesanj. The study included 50 women (singleton pregnancy, 28-37 week) with imminent preterm labor diagnosed by cervical biometry and modified Bishop score) (examinees) and 30 healthy pregnant women (control group). The presence of IGFBP-1 was tested in cervical secretion several times in weeks 28-37 until a positive test was shown. Results IGFBP-1 was positive in 43 (86%) examinees and in six (20%) patients from the control group (p=0.001). In 31 (62%) examinees APT was positive in weeks 28-30, and in nine (18%) in weeks 31- 33, while three (6%) examinees had positive test in 34-37 week; in the control group, three (10%) were tested positive in weeks 31-33 and three (10%) in weeks 34-37. At first testing (28-30 weeks) APT was statistically significantly more frequently positive in the examined group (p<0.05). Later, tests did not find statistically significant difference in the frequency of positivity between the control and examined group (p=0.08). Conclusion Elevated values of IGFBP -1 in cervical secretion were highly correlated with preterm labor. Screening for IGFBP could help in preventing preterm labor and its complications.

[Clinical study of Jiawei Bazhen decoction combined with oxytocin for cervical ripening of qi and blood deficiency type of pregnant women].

To study preliminarily the effect of Jiawei Bazhen decoction combined with oxytocin in promoting cervical ripening of full-term pregnancy women who were in the deficiency of qi and blood type through the syndrome differentiation of traditional Chinese medicine (TCM). 180 patients that met the inclusion criteria of the study were randomly divided into three groups: the control group(oxytocin group), the treatment group (Jiawei Bazhen decoction combined with oxytocin group), the blank control group (expected and observation group). Cervical maturity score (Bishop score), vaginal and cervical secretions fetal fibronectin (FFN), the result of induced labor, the result of mother and baby were observed in each group before and after treatment. The result comes out that the cervical Bishop score of pregnant women for treatment group were significantly higher than the control group and blank control group after treatment (P < 0.05). The FFN of pregnant women for the treatment group were significantly different from the control group and blank control group after treatment (P < 0.05). The pregnancy outcome of the three groups: the labor rate and rate of vaginal delivery of the treatment group were higher than the other two groups, and the difference was statistically significant (P < 0.05). The cesarean section rate of the treatment group was significantly lower than the other two groups, the difference was also statistically significant (P < 0.05). The three groups did not appear the phenomenon of neonatal asphyxia. Jiawei Bazhen decoction combined with oxytocin is effective in producing cervical ripening and induce labor. It is convenient, safe and reliable, for it is no obvious adverse effects on mother and fetus, but effective in reducing the rate of cesarean section, and playing a positive role in promoting natural delivery.

Factors implicated in the initiation of human parturition in term and preterm labor: a review.

After accommodating the pregnancy for an average of 40 weeks, the uterus expels the fetus, the placenta and the membranes through the birth canal in a process named parturition. The absolute sequence of events that trigger and sustain human parturition are not yet fully clarified. Evidence suggests that spontaneous preterm and term labor seem to share a common inflammatory pathway. However, there are several other factors being involved in the initiation of human parturition. Placental corticotropin releasing hormone production seems to serve as a placental clock that might be set to ring earlier or later determining the duration of pregnancy and timing of labor. Estrogens do not cause contractions but their properties seem to capacitate uterus to coordinate and enhance contractions. Cytokines, prostaglandins, nitric oxide and steroids seem also to induce ripening by mediating remodeling of the extracellular matrix and collagen. Infection and microbe invasion resulting in chorioamnionitis also represents a common cause of early preterm labour. This review provides an overview of all these factors considered to be implicated in the initiation of human parturition.

Prostaglandins are essential for cervical ripening in LPS-mediated preterm birth but not term or antiprogestin-driven preterm ripening.

Globally, an estimated 13 million preterm babies are born each year. These babies are at increased risk of infant mortality and life-long health complications. Interventions to prevent preterm birth (PTB) require an understanding of processes driving parturition. Prostaglandins (PGs) have diverse functions in parturition, including regulation of uterine contractility and tissue remodeling. Our studies on cervical remodeling in mice suggest that although local synthesis of PGs are not increased in term ripening, transcripts encoding PG-endoperoxide synthase 2 (Ptgs2) are induced in lipopolysaccharide (LPS)-mediated premature ripening. This study provides evidence for two distinct pathways of cervical ripening: one dependent on PGs derived from paracrine or endocrine sources and the other independent of PG actions. Cervical PG levels are increased in LPS-treated mice, a model of infection-mediated PTB, consistent with increases in PG synthesizing enzymes and reduction in PG-metabolizing enzymes. Administration of SC-236, a PTGS2 inhibitor, along with LPS attenuated cervical softening, consistent with the essential role of PGs in LPS-induced ripening. In contrast, during term and preterm ripening mediated by the antiprogestin, mifepristone, cervical PG levels, and expression of PG synthetic and catabolic enzymes did not change in a manner that supports a role for PGs. These findings in mice, supported by correlative studies in women, suggest PGs do not regulate all aspects of the parturition process. Additionally, it suggests a need to refocus current strategies toward developing therapies for the prevention of PTB that target early, pathway-specific processes rather than focusing on common late end point mediators of PTB.

The expression of prostaglandin receptors EP3 and EP4 in human cervix in post-term pregnancy differs between failed and successful labor induction.

OBJECTIVE: To investigate expression and localization of prostaglandin receptors EP1-4 and FP and localization of stromal factors CTGF (connective tissue growth factor), furin, calgranulin B and ALOX15 (arachidonate 15-lipooxygenase) in human cervical tissue from post-term women with failed or successful labor induction after prostaglandin priming. DESIGN: Experimental prospective clinical study. SETTING: Tertiary obstetric care center. POPULATION: Twenty-six women giving birth post-term, with failed or successful labor induction, and a control group consisting of 19 women with spontaneous onset of labor and delivery at term. METHODS: Biopsies were obtained from post-term women with successful (responders; R) and failed (non-responders; NR) labor induction. Women with spontaneous delivery at term were included as controls (C). mRNA expression was determined with real time PCR, protein expression and localization with immunohistochemistry. MAIN OUTCOME MEASURES: Comparisons of mRNA and protein expressions between post-term pregnancies with failed and successful labor induction as well as term controls. RESULTS: EP4 mRNA expression was down-regulated concomitant with an up-regulation of EP3 mRNA expression in cervix from the NR group as compared with the R group. In stroma, immunoreactivity of the EP4 protein was increased in the NR group as compared with R and C groups. CONCLUSIONS: Failure of cervical ripening, after local application of prostaglandins for labor induction, may be caused by the increased expression of EP3 and concomitant decrease in EP4 expression.

The effect of a Foley catheter balloon on cervical ripening.

The Foley catheter balloon may affect cervical ripening through changes in biochemical mediators by immunoassay and immunohistochemistry, when it is used for pre-induction cervical ripening. The aim of the study was to evaluate the changes in the biochemical mediators from the extra-amniotic space and immunohistochemistry in ripened cervical tissue after the insertion of a Foley catheter balloon (FCB) for pre-induction cervical ripening. A total of 18 pregnant women with a Bishop's score < 6, who were undergoing labour induction, were evaluated in this prospective study. The FCB was irrigated with 10 ml of phosphate buffered saline and the irrigant was collected 0, 2, 4 and 8 h after placement of the FCB or until spontaneous expulsion of the FCB occurred. Irrigant specimens were also collected from 10 spontaneous labouring (SL) women in the active phase of labour. The levels of interleukin (IL)-6, IL-8, matrix metalloproteinase (MMP)-8 and NO were measured. Cervical specimens were obtained from 12 women, including four undergoing induction; four SL and four non-pregnant (NP) women. Immunohistochemical staining was performed to localise hyaluronic acid synthase (HAS)-1, IL-6, IL-8, MMP-8, endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS). Results showed that the levels of IL-6, IL-8, and MMP-8 significantly increased over time in FCB group (p < 0.01). In the immunohistochemical analysis of cervical tissues, immunoreactivity of HAS-1 in the after FCB group was stronger than any of the other groups. The protein expressions of IL-6, IL-8, MMP-8, eNOS and iNOS were more prominent in the after FCB and SL groups than in the NP and the before FCB groups. iNOS was only observed in the after FCB and SL groups. It was concluded that FCB may affect cervical ripening through changes in biochemical mediators by immunoassay and immunohistochemistry, when it is used for pre-induction cervical ripening.

Correlation between an absence of cervical gland area on transvaginal sonography and cervical mucus hyaluronic acid levels in women with threatened preterm delivery.

PURPOSE: Transvaginal sonographic findings of an absent cervical gland area (CGA) and a short cervical length (CL) are frequently observed in patients with threatened preterm delivery. The present study aimed to clarify whether sonographic findings are due to active production of hyaluronic acid (HA)in the cervix. METHODS: Possible relationships between sonographic findings of the presence or absence of the CGA and/or a short CL and cervical mucus HA concentration were investigated in 68 women with threatened preterm delivery at 22 ­ 31 weeks' gestation and 136 women without threatened preterm delivery as controls. RESULTS: HA levels were higher in women with threatened preterm delivery (68.0 ng/mL) than in controls (39.0 ng/mL; P = 0.001). Similarly, HA levels were higher in women with preterm labor showing an absent CGA and a short CL than in women with threatened preterm delivery without such findings (P < 0.01). Stepwise multivariate logistic regression identified an absent CGA and threatened preterm delivery as independent predictors of high HA levels (P = 0.04). HA concentration was not predictive for preterm delivery. CONCLUSION: A sonographic finding of an absent CGA reflects high HA levels in the cervix with threatened preterm delivery.

Hypoxia and PGE(2) regulate MiTF-CX during cervical ripening.

The mechanisms by which the cervix remains closed during the massive uterine expansion of pregnancy are unknown. IL-8 is important for recruitment of immune cells into the cervical stroma, matrix remodeling, and dilation of the cervix during labor. Previously, we have shown that several cytokine genes transcriptionally repressed in the cervix during gestation are activated during cervical ripening and dilation. IL-8 gene expression is repressed in cervical stromal cells during pregnancy by the transcription factor microphthalmia-associated transcription factor (MiTF-CX). Here, we tested the hypothesis that hypoxia and the transcription factor hypoxia inducible factor-1α (HIF-1α) may regulate MiTF-CX and cervical ripening. Using tissues from women during pregnancy before and after cervical ripening, we show that, during cervical ripening, HIF-1α was stabilized and relocalized to the nucleus. Further, we found that hypoxia and two hypoxia mimetics that stabilize HIF-1α activated the transcriptional repressor differentiated embryo chondrocyte-expressed gene 1, which bound to sites in the MiTF-CX promoter crucial for its positive autoregulation. Ectopic overexpression of MiTF-CX abrogated hypoxia-induced up-regulation of IL-8 gene expression. We also show that activation of HIF-1α induced cyclooxygenase-2 and that prostaglandin E(2) repressed MiTF-CX. We conclude that hypoxia and stabilization of the transcription factor HIF-1α result in up-regulation of differentiated embryo chondrocyte-expressed gene 1, loss of MiTF, and absence of MiTF binding to the IL-8 promoter, which in turn leads to up-regulation of IL-8 gene expression. Hypoxia also up-regulated cyclooxygenase-2, leading to prostaglandin E(2)-mediated loss of MiTF in cervical stromal cells. The results support a pivotal role for hypoxia and HIF-1α in the cervical ripening process during pregnancy.

Relaxin regulates hyaluronan synthesis and aquaporins in the cervix of late pregnant mice.

Cervical ripening is associated with loss of structural integrity and tensile strength, thus enabling the cervix to dilate at term. It is characterized by changes in glycosaminoglycan composition, increased water content, and a progressive reorganization of the collagen network. The peptide hormone relaxin via interaction with its receptor, relaxin family peptide receptor 1 (RXFP1), promotes tissue hydration and increases cervical hyaluronan (HA) concentrations, but the mechanisms that regulate these effects are not known. This study in relaxin mutant (Rln(-/-)) mice tested the hypothesis that relaxin regulates HA synthase and aquaporin (AQP) expression in the cervix. We also assessed expression of the RXFP1 protein by immunohistochemistry. Pregnant Rln(-/-) mice had lower Has2 and Aqp3 expression on d 18.5 of pregnancy and decreased cervical HA compared with wild-type Rln(+/+) mice. Chronic infusion of relaxin for 4 or 6 d in pregnant Rln(-/-) mice reversed these phenotypes and increased Has2 and Aqp3 compared with placebo controls. Relaxin-treated mice also had lower Has1 and Aqp5. Changes in gene expression were paralleled by increases in cervical HA and variations in AQP3 and AQP5 protein localization in epithelial cells of Rln(-/-) cervices. Our findings demonstrate that relaxin alters AQP expression in the cervix and initiates changes in glycosaminoglycan composition through increased HA synthesis. These effects are likely mediated through RXFP1 localized to subepithelial stromal cells and epithelial cells. We suggest these actions of relaxin collectively promote water recruitment into the extracellular matrix to loosen the dense collagen fiber network.

Immunolocalization of adipocytes and prostaglandin E2 and its four receptor proteins EP1, EP2, EP3, and EP4 in the caprine cervix during spontaneous term labor.

The mechanisms of cervical ripening and dilation in mammals remain obscure. Information is lacking about the localization of prostaglandin E(2) (PGE(2))-producing cells and PGE(2) receptors (EP) in intrapartum cervix and whether cervical dilation at parturition is an active process. To reveal these mechanisms, immunolocalization of EP1-EP4 (official gene symbols PTGER1-PTGER4) and PGE(2)-producing cells in caprine cervix during nonpregnancy, pregnancy, and parturition was assayed by immunohistochemistry (IHC); the mRNA expression levels of PTGS2, PTGER2 (EP2), and PTGER4 (EP4) were determined using quantitative PCR; and the existence of adipocytes in the cervix at various stages was demonstrated with Oil Red O staining and IHC of perilipin A. The results suggested that in intrapartum caprine cervix staining of the PGE(2) was observed in the overall tissues, for example, blood vessels, canal or glandular epithelia, serosa, circular and longitudinal muscles, and stroma in addition to adipocytes; EP2 was detectable in all the tissues other than glandular epithelia; EP4 was strongly expressed in all the tissues other than serosa; EP1 was detected mainly in arterioles and canal or glandular epithelia; and EP3 was poorly expressed only in stroma, canal epithelia, and circular muscles. Little or no expression of EP2, EP3, and EP4 as well as PGE(2) in all cervical tissues was observed during nonpregnancy and pregnancy except for the strong expression of EP1 in canal or glandular epithelia during pregnancy. The mRNA expression levels of PTGS2, PTGER2, and PTGER4 were significantly higher in intrapartum than nonpregnant and midpregnant cervices (P < 0.01). Adipocytes appear only in the intrapartum cervix. These results support the concept that PGE(2) modulates specific functions in various anatomical structures of the caprine cervix at labor and the appearance of adipocytes at labor is likely related to caprine cervical dilation.

[Effect of the optimized traditional acupuncture prescription for accouchement on cervical ripening in late-stage pregnant rats].

OBJECTIVE: To observe the mechanism of the optimized traditional acupuncture prescription for accouchement on cervical ripening based on the molecular biology by observing related indices of cervical ripening in late-stage pregnant rats. METHODS: Twenty initial pregnant Wistar rats were randomly divided into an electroacupuncture (EA) group (n = 10) and a model group (n = 10), and other 10 non-pregnancy female rats with same lot were selected as a blank control group. EA group was treated with the optimized traditional acupuncture prescription for accouchement on the 20th day of pregnant, which performed EA at bilateral "Hegu" (LI 4) for 20 min and then at bilateral "Sanyinjiao" (SP 6) for 5 min with 2 Hz/50 Hz sparse-dense wave, while the other groups without acupuncture intervention. The contents of matrix metalloproteinase 9 (MMP-9) and interleukin 8 (IL-8) in cervix tissue were detected by ELISA method. RESULTS: Compared with the blank control group, the contents of MMP-9 and IL-8 in the model group were increased significantly (both P < 0.01). Compared with the model group, the contents of MMP-9 and IL-8 in the EA group were increased significantly (P < or = 0.05). CONCLUSION: Optimized traditional acupuncture prescription for accouchement can increase the contents of MMP-9 and IL-8 in cervix tissue of late-stage pregnant rats so as to promote cervical ripening, and the mechanism of EA in promoting cervical ripening is explained from the perspective of molecular biology.

Cervical softening during pregnancy: regulated changes in collagen cross-linking and composition of matricellular proteins in the mouse.

A greater understanding of the parturition process is essential in the prevention of preterm birth, which occurs in 12.7% of infants born in the United States annually. Cervical remodeling is a critical component of this process. Beginning early in pregnancy, remodeling requires cumulative, progressive changes in the cervical extracellular matrix (ECM) that result in reorganization of collagen fibril structure with a gradual loss of tensile strength. In the current study, we undertook a detailed biochemical analysis of factors in the cervix that modulate collagen structure during early mouse pregnancy, including expression of proteins involved in processing of procollagen, assembly of collagen fibrils, cross-link formation, and deposition of collagen in the ECM. Changes in these factors correlated with changes in the types of collagen cross-links formed and packing of collagen fibrils as measured by electron microscopy. Early in pregnancy there is a decline in expression of two matricellular proteins, thrombospondin 2 and tenascin C, as well as a decline in expression of lysyl hydroxylase, which is involved in cross-link formation. These changes are accompanied by a decline in both HP and LP cross-links by gestation Days 12 and 14, respectively, as well as a progressive increase in collagen fibril diameter. In contrast, collagen abundance remains constant over the course of pregnancy. We conclude that early changes in tensile strength during cervical softening result in part from changes in the number and type of collagen cross-links and are associated with a decline in expression of two matricellular proteins thrombospondin 2 and tenascin C.