Dynamic collagen changes in cervix during the first trimester and decreased collagen content in cervical insufficiency

Systems biology approach: identification of hub genes, signaling pathways, and molecular docking of COL1A1 gene in cervical insufficiency

The collagen type I alpha 1 (COL1A1, OMIM #120,150) gene, encoding the alpha-1 chain of type I collagen (UniProt #P02452), plays a key role in life-homeostasis due to its remarkable involvement in collagen synthesis. It is a promising candidate gene implicated in the pathogenesis of cervical insufficiency (CI). This study aimed to identify genetic variations within the COL1A1 gene that contribute to the development of CI. Polymerase chain reaction (PCR) and amplicon sequencing were implemented for single nucleotide polymorphisms (SNPs) detection (+ 1245G/T, SP1 rs1800012), which revealed wild-type sequence for targeted SNPs in enrolled proband indicated negative results regarding COL1A1 gene involvement for current form of CI. It allows further investigation of other closely connected genes probed in this study. Computational approaches viz. Protein-protein interaction (PPI), gene ontology (GO), and pathway participation were used to identify the crucial hub genes and signaling pathways for COL1A1 and CI. Using the Yet Another Scientific Artificial Reality Application (YASARA) software, molecular docking, and molecular dynamic (MD) simulation with the oxytocin (CID 439,302), estradiol (CID 129,728,744), progesterone (CID 5994) and hydroxyprogesterone (CID 150,788) were done. Interactive bioinformatics analysis demonstrated that the COL1A1 and more than 10 collagen sister genes had a strong connection with CI. In sum, the findings of this study provide insights into a modus operandi that can be utilized to illuminate the path toward studying sister genes and smooth diagnosis of CI. These findings have implications for understanding the foundational process of the condition and potentially developing screening, diagnostic, and therapeutic interventions.

Graphical Abstract

Incidence, characteristics, and maternal outcomes of pregnancy with uterine prolapse

BACKGROUND

Gravid uterine prolapse refers to abnormal descent of the uterus during pregnancy. It is a rare pregnancy complication and its clinical characteristics and obstetrical outcomes are not well understood.

OBJECTIVE

This study aimed to assess the national-level incidence, characteristics, and maternal outcomes of pregnancies complicated by gravid uterine prolapse.

STUDY DESIGN

This retrospective cohort study queried the Healthcare Cost and Utilization Project's National Inpatient Sample. The study population was 14,647,670 deliveries from January 2016 to December 2019. The exposure assignment was the diagnosis of uterine prolapse. The coprimary outcome measures were incidence rate, clinical and pregnancy characteristics, and delivery outcomes of patients with gravid uterine prolapse. The inverse probability of treatment weighting cohort was created to mitigate the difference in prepregnancy confounding factors, followed by adjusting for pregnancy and delivery factors.

RESULTS

The incidence of gravid uterine prolapse was 1 in 4209 deliveries (23.8 per 100,000). In a multivariable analysis, older age (≥40 years; adjusted odds ratio, 3.21; 95% confidence interval, 2.70-3.81); age from 35 to 39 years (adjusted odds ratio, 2.66; 95% confidence interval, 2.37-2.99); Black (adjusted odds ratio, 1.48; 95% confidence interval, 1.34-1.63), Asian (adjusted odds ratio, 1.45; 95% confidence interval, 1.28-1.64), and Native American (adjusted odds ratio, 2.17; 95% confidence interval, 1.63-2.88) race/ethnicity; tobacco use (adjusted odds ratio, 1.19; 95% confidence interval, 1.03-1.37); grand multiparity (adjusted odds ratio, 1.78; 95% confidence interval, 1.24-2.55); and history of pregnancy losses (adjusted odds ratio, 2.20; 95% confidence interval, 1.48-3.26) were the patient characteristics associated with increased risk of gravid uterine prolapse. Current pregnancy characteristics associated with gravid uterine prolapse included cervical insufficiency (adjusted odds ratio, 3.25; 95% confidence interval, 1.94-5.45), preterm labor (adjusted odds ratio, 1.53; 95% confidence interval, 1.18-1.97), preterm premature rupture of membranes (adjusted odds ratio, 1.40; 95% confidence interval, 1.01-1.94), and chorioamnionitis (adjusted odds ratio, 1.64; 95% confidence interval, 1.18-2.28). Delivery characteristics associated with gravid uterine prolapse included early-preterm delivery at <34 weeks' gestation (69.1 vs 32.0 per 1000; adjusted odds ratio, 1.86; 95% confidence interval, 1.34-2.59) and precipitate labor (35.2 vs 20.1; adjusted odds ratio, 1.73; 95% confidence interval, 1.22-2.44). Moreover, risks of postpartum hemorrhage (112.1 vs 44.4 per 1000; adjusted odds ratio, 2.70; 95% confidence interval, 2.20-3.32), uterine atony (32.0 vs 15.7; adjusted odds ratio, 2.10; 95% confidence interval, 1.46-3.03), uterine inversion (9.6 vs 0.3; adjusted odds ratio, 31.97; 95% confidence interval, 16.60-61.58), shock (3.2 vs 0.7; adjusted odds ratio, 4.18; 95% confidence interval, 1.41-12.40), blood product transfusion (22.4 vs 11.1; adjusted odds ratio, 2.06; 95% confidence interval, 1.34-3.18), and hysterectomy (7.5 vs 2.3; adjusted odds ratio, 3.02; 95% confidence interval, 1.40-6.51) were increased in the gravid uterine prolapse group compared with the nonprolapse group. Conversely, patients with gravid uterine prolapse were less likely to deliver via cesarean delivery compared with those without gravid uterine prolapse (200.6 vs 322.8 per 1000; adjusted odds ratio, 0.51; 95% confidence interval, 0.44-0.61).

CONCLUSION

This nationwide analysis suggests that pregnancy with gravid uterine prolapse is uncommon but associated with several high-risk pregnancy characteristics and adverse delivery outcomes.

Can Stria Gravidarum Predict Surgical Fluid Loss in Cesarean Section?

INTRODUCTION

Alterations in collagen subtypes and matrix can potentially cause fluid loss in surgery which is important in terms of liquid loss.

OBJECTIVES

The study aimed to analyze stria gravidarum (SG) and its severity in pregnant women who had undergone cesarean section (CS) and to evaluate surgical fluid loss (SFL) that occurred during CS operation.

METHODS

The research was designed as a prospective clinical cohort study to compare the amount of SFL in the second cesarean section with the severity of SG at 34-37 weeks pregnant (N 308). The severity of SG was evaluated in the preoperative period using the Davey scoring. All patients were defined none, mild stria and severe stria. The SFL was calculated by weighing the pre-and post-operative weights of the sponges.

RESULTS

The weight gain (P = 0.008) and body mass index (BMI, P = 0.017) gradually increased toward severe SG. In correlation analysis of SFL, a positive correlation was found with Davey (r=0.791; P = 0.0001), weight gained during pregnancy (r=0.328; P = 0.0001), BMI (r=0.453; P = 0.001) and newborn weight (r=0.139; P = 0.003). In the receiver operating characteristic for the predictability of SG severity on SFL, severe SG showed a potential for SFL with 95.1% specificity and 93.2% sensitivity at 791 cut-offs (area under the curve:0.987; P = 0.00001; 95% confidence interval: 0.977-0.997).

CONCLUSIONS

The SG severity and SFL showed a very strong relationship, which was a very important finding that would affect the approach of the surgeons to the patients with SG in terms of fluid loss in CS.

Different expressions of aquaporin water channels and macrophages infiltration in human cervix remodeling during pregnancy

Despite aquaporin water channels (AQPs) play a critical role in maintaining water homeostasis in female reproductive tract and prompt a gradual increase in water content in cervical edema as pregnancy progressed, their relationship with macrophage infiltration and collagen content in human cervical remodeling need to be further investigated. This is the first study to examine the expression and localization of AQP3, AQP4, AQP5, AQP8 and macrophages simultaneously in human cervical ripening. The immunoreactivity of these AQPs was 2.6 to 6-fold higher on gestational weeks 26 (GD26W) than that on GD6W and GD15W, but AQP4 expression on GD39W dropped a similar extent on GD15W, other AQPs continued to rise on GD39W. The AQP3, AQP4 and AQP5 intensity seemed more abundant in cervical stroma than in the perivascular area on GD26W; the distribution of AQP3, AQP5 and AQP8 in cervical stroma was equivalent to that in the perivascular area on GD39W. Macrophage numbers were 1.7-fold higher in subepithelium region and 3.0-fold higher in center area on GD26W than that on GD15W; such numbers remained elevated on GD39W. The electron micrographs showed that cervical extensibility increased significantly on GD26W and GD39W accompanied with increased macrophage infiltration, cervical water content and much more space among collagen fibers. These findings suggest that the upregulation of AQPs expression in human cervix is closely related to enhanced macrophage infiltration during pregnancy; there may be a positive feedback mechanism between them to lead the increase of water content and the degradation of collagen.

Extracellular Matrix Rigidity Modulates Human Cervical Smooth Muscle Contractility-New Insights into Premature Cervical Failure and Spontaneous Preterm Birth

Spontaneous preterm birth (sPTB), a major cause of infant morbidity and mortality, must involve premature cervical softening/dilation for a preterm vaginal delivery to occur. Yet, the mechanism behind premature cervical softening/dilation in humans remains unclear. We previously reported the non-pregnant human cervix contains considerably more cervical smooth muscle cells (CSMC) than historically appreciated and the CSMC organization resembles a sphincter. We hypothesize that premature cervical dilation leading to sPTB may be due to (1) an inherent CSMC contractility defect resulting in sphincter failure and/or (2) altered cervical extracellular matrix (ECM) rigidity which influences CSMC contractility. To test these hypotheses, we utilized immunohistochemistry to confirm this CSMC phenotype persists in the human pregnant cervix and then assessed in vitro arrays of contractility (F:G actin ratios, PDMS pillar arrays) using primary CSMC from pregnant women with and without premature cervical failure (PCF). We show that CSMC from pregnant women with PCF do not have an inherent CSMC contractility defect but that CSMC exhibit decreased contractility when exposed to soft ECM. Given this finding, we used UPLC-ESI-MS/MS to evaluate collagen cross-link profiles in the cervical tissue from non-pregnant women with and without PCF and found that women with PCF have decreased collagen cross-link maturity ratios, which correlates to softer cervical tissue. These findings suggest having soft cervical ECM may lead to decreased CSMC contractile tone and a predisposition to sphincter laxity that contributes to sPTB. Further studies are needed to explore the interaction between cervical ECM properties and CSMC cellular behavior when investigating the pathophysiology of sPTB.

Changes in alpha-7 nicotinic acetylcholine receptor and macrophage polarization state participate in the regulation of cervical remodeling in pregnant rats†

To test the hypothesis that changes in alpha-7 nicotinic acetylcholine receptor (α7nAChR) expression on macrophages and macrophage polarization participate in cervical remodeling during normal pregnancy, pregnant rats from gestational days (GDs) 14, 16, 18, 20, and 22 were used in the present study. The expression of α7nAChR on macrophages and the numbers of M1 and M2 macrophages were detected by double immunofluorescence staining. The levels of α7nAChR and collagens were detected by western blotting. M1 markers (inducible nitric oxide synthase and inflammatory cytokines) and M2 markers (arginase 1, anti-inflammatory cytokines) were detected to evaluate the macrophage polarization state by immunohistochemistry staining, western blotting, and the enzyme-linked immunosorbent assay. Matrix metalloproteinase 9 (MMP-9) expression was determined by immunohistochemistry staining and western blotting. We found that the α7nAChR expression on macrophages significantly decreased on GD22 compared to GDs 14, 16, 18, and 20. There was an increased number of M1 macrophages and decreased number of M2 macrophages in late pregnancy. The expression of M1 macrophage biomarkers was much higher on GDs 20 and 22 than on GDs 14, 16, and 18, but expression of M2 biomarkers decreased on GDs 20 and 22 compared to GDs 14, 16, and 18. MMP-9 expression was higher on GD22 than on GDs 14, 16, 18, and 20, and collagen expression significantly decreased on GDs 18, 20, and 22 compared to GD14. Our results indicated that the decreased expression of α7nAChR and increased number of M1 macrophages are associated with cervical remodeling.

<p>The Comparative Study of Cervical Shear Wave Elastography Between Twin and Singleton Pregnancy</p>

Objective

To compare the cervical shear wave elastography (SWE) by using transvaginal ultrasound (TVS) between twin and singleton pregnant women.

Materials and Methods

This was a prospective cohort study involving the twin and singleton pregnant women who attended the antenatal care at Ramathibodi Hospital, Bangkok, Thailand. The participants who met the inclusion criteria were serially measured the shear wave speed (SWS) by using TVS at early, mid-, and third trimester. The changes in SWS with advancing gestational age between twin and singleton pregnancies were evaluated. The gestational age at delivery and spontaneous preterm delivery rate were also analyzed.

Results

A total of 36 twin pregnancies and 38 singleton pregnancies were analyzed. No significant difference in baseline characteristics, except the age of participants (twin pregnancies 33.1±4.6 years, singleton pregnancies 29.9±5.4 years, p-value = 0.006) was observed. The cervical SWS decreased with advancing gestational age in both twin and singleton pregnancy, but there was a statistically significant difference of cervical SWS at the lower point in mid-trimester (twin pregnancies 2.27±0.4, singleton pregnancies 2.71±0.6 m/s, p-value = 0.001). However, no significant difference in cervical SWS at the upper point and the lower point in the early and third trimester was demonstrated. Even though the gestational age at delivery between both groups revealed a significant difference (twin pregnancies 35.9±2.8, singleton pregnancies 37.6±2.9 wk., p-value = 0.008) but the spontaneous preterm delivery rate did not differ significantly (twin pregnancies 22.2%, singleton pregnancies 15.8%, p-value = 0.483).

Conclusion

The mid-trimester cervical SWS measurement at the lower point detects the difference in cervical softness between twin pregnancies and singleton pregnancies. The cervical SWS might be an additional option for monitoring the change in cervical softness in twin pregnancies.

Assessment of the cervix in pregnant women with a history of cervical insufficiency during the first trimester using elastography

INTRODUCTION

To investigate changes in first trimester cervical elastography, cervical length and endocervical canal width in pregnant women with a history of cervical insufficiency, and further discuss the possibility of using these markers as predictors of cervical insufficiency in early pregnancy.

MATERIAL AND METHODS

This was an observational ultrasound study of first trimester cervical changes in singleton pregnancies between January 2016 and June 2018. Cervical elastography, cervical length and endocervical canal width were measured during the first trimester. Strain elastography was used to estimate the softness of anterior and posterior cervical lips and was expressed as percentages (strain rate).

RESULTS

Of the 339 pregnant women enrolled, 24 had a history of cervical insufficiency. The anterior cervical lip was significantly softer in the cervical insufficiency group (strain rate: 0.19% ± 0.05% vs 0.11% ± 0.04%; P < .001). Cervical length was significantly shorter in the cervical insufficiency group (36.3 ± 4.8 mm vs 38.3 ± 3.8 mm; P = .014). Endocervical canal width was significantly wider in the cervical insufficiency group (5.7 ± 1.1 mm vs 5.2 ± 0.7 mm; P = .001). Receiver operating characteristic curve analyses revealed that the optimal cut-off values of anterior cervical lip, cervical length and endocervical canal width to confirm the diagnosis of cervical insufficiency were 0.15%, 35.5 mm and 5.75 mm, respectively. In multivariate logistic regression analysis, significant differences were still observed in anterior cervical strain rate (adjusted odds ratio [OR] 53.78, 95% [confidence interval [CI] 11-270; P < .001) and endocervical canal width (adjusted OR, 5.41, 95% CI,1.2-24.7; P = .029).

CONCLUSIONS

First trimester cervical elastography is a valuable tool in the assessment of women with a history of cervical insufficiency. The anterior cervical lip was significantly softer in women with a history of cervical insufficiency, and the sensitivity and specificity of anterior cervical lip strain were better than that of cervical length and endocervical canal width.

Immunobiology of Cervix Ripening

The cervix is the essential gatekeeper for birth. Incomplete cervix remodeling contributes to problems with delivery at or post-term while preterm birth is a major factor in perinatal morbidity and mortality in newborns. Lack of cervix biopsies from women during the period preceding term or preterm birth have led to use of rodent models to advanced understanding of the mechanism for prepartum cervix remodeling. The critical transition from a soft cervix to a compliant prepartum lower uterine segment has only recently been recognized to occur in various mammalian species when progesterone in circulation is at or near the peak of pregnancy in preparation for birth. In rodents, characterization of ripening resembles an inflammatory process with a temporal coincidence of decreased density of cell nuclei, decline in cross-linked extracellular collagen, and increased presence of macrophages in the cervix. Although a role for inflammation in parturition and cervix remodeling is not a new concept, a comprehensive examination of literature in this review reveals that many conclusions are drawn from comparisons before and after ripening has occurred, not during the process. The present review focuses on essential phenotypes and functions of resident myeloid and possibly other immune cells to bridge the gap with evidence that specific biomarkers may assess the progress of ripening both at term and with preterm birth. Moreover, use of endpoints to determine the effectiveness of various therapeutic approaches to forestall remodeling and reduce risks for preterm birth, or facilitate ripening to promote parturition will improve the postpartum well-being of mothers and newborns.

α-Tocopherol Potentiates the Cervical Resistance Decreasing Effects of COX Inhibitors in Pregnant Rats: The Putative Role of Cyclooxygenase-2 Inhibition

Vitamin E and their analogs as antioxidant and lipid-soluble compounds can have diverse effects on the physiologic processes. By binding to receptors and enzymes, they may modify the action of drugs. It has been proved that α-tocopherol succinate modifies the effects of β 2 agonist terbutaline and cyclooxygenase (COX) inhibitors on rat trachea and myometrium. Our aim was to investigate how α-tocopherol and COX inhibitors may influence cervical resistance in rats. The cervical resistance of nonpregnant and 22 day-pregnant Sprague-Dawley rats was determined in an isolated organ bath in vitro. α-Tocopherol-succinate (10-7 M) was used, whereas the COX-nonselective diclofenac (10-6 M), the COX-2-selective rofecoxib (10-6 M), and the COX-1-selective SC-560 (10-6 M) were applied as inhibitors. The COX activities of the cervices were measured by enzyme immunoassay. The modifying effect of single doses of COX inhibitors and tocopherol on the onset of labor was investigated in vivo. The cervical resistance of nonpregnant samples was not changed by either α-tocopherol or COX inhibitors. On pregnant cervices, tocopherol, diclofenac, or rofecoxib pretreatment decreased cervical resistance that was further reduced by COX inhibitors after pretreatment with tocopherol. α-Tocopherol elicited a significant COX-2 enzyme inhibition in cervical samples from pregnant rats. By coadministration of tocopherol and rofecoxib, the parturition was initiated earlier than in the other groups. It is supposed that COXs play a significant role not only in cervical ripening, but also in the contraction of the cervical smooth muscle a few hours before parturition. This latter action may be developed by COX-2-liberated prostaglandins.

Cervical alterations in pregnancy

Spontaneous preterm birth (SPTB), defined as delivery before 37 weeks' gestation, remains a significant obstetric dilemma even after decades of research in this field. Although trends from 2007 to 2014 showed the rate of preterm birth slightly decreased, the CDC recently reported the rate of preterm birth has increased for two consecutive years since 2014. Currently, 1 in 10 pregnancies in the US still end prematurely. In this chapter, we focus on the "compartment" of the cervix. The goal is to outline the current knowledge of normal cervical structure and function in pregnancy and the current knowledge of how the cervix malfunctions lead to SPTB. We review the mechanisms by which our current interventions are hypothesized to work. Finally, we outline gaps in knowledge and future research directions that may lead to novel and effective interventions to prevent premature cervical failure and SPTB.

The pathophysiology of human premature cervical remodeling resulting in spontaneous preterm birth: Where are we now?

Approximately one in ten (approximately 500,000) pregnancies results in preterm birth (PTB) annually in the United States. Although we have seen a slight decrease in the U.S. PTB rate between 2007 and 2014, data from 2014 to 2015 shows the preterm birth rate has slightly increased. It is even more intriguing to note that the rate of PTB has not significantly decreased since the 1980s. In order to decrease the rate of spontaneous preterm birth (sPTB), it is imperative that we improve our understanding of normal and abnormal reproductive tissue structure and function and how these tissues interact with each other at a cellular and biochemical level. Since other chapters in this issue will be focusing on the myometrium and fetal membranes, the goal of this chapter is to focus on the compartment of the cervix. We will review the current literature on normal and abnormal human cervical tissue remodeling and identify gaps in knowledge. Our goal is also to introduce a revised paradigm of normal cervical tissue structure and function which will provide novel research opportunities that may ultimately lead to developing safe and effective interventions to significantly decrease the rate and complications of prematurity.

A new paradigm for the role of smooth muscle cells in the human cervix

BACKGROUND

Premature cervical remodeling resulting in spontaneous preterm birth may begin with premature failure or relaxation at the internal os (termed "funneling"). To date, we do not understand why the internal os fails or why funneling occurs in some cases of premature cervical remodeling. Although the human cervix is thought to be mostly collagen with minimal cellular content, cervical smooth muscle cells are present in the cervix and can cause cervical tissue contractility.

OBJECTIVE

To understand why the internal os relaxes or why funneling occurs in some cases of premature cervical remodeling, we sought to evaluate cervical smooth muscle cell content and distribution throughout human cervix and correlate if cervical smooth muscle organization influences regional cervical tissue contractility.

STUDY DESIGN

Using institutional review board-approved protocols, nonpregnant women <50 years old undergoing hysterectomy for benign indications were consented. Cervical tissue from the internal and external os were immunostained for smooth muscle cell markers (α-smooth muscle actin, smooth muscle protein 22 calponin) and contraction-associated proteins (connexin 43, cyclooxygenase-2, oxytocin receptor). To evaluate cervical smooth muscle cell morphology throughout the entire cervix, whole cervical slices were obtained from the internal os, midcervix, and external os and immunostained with smooth muscle actin. To correlate tissue structure with function, whole slices from the internal and external os were stimulated to contract with 1 μmol/L of oxytocin in organ baths. In separate samples, we tested if the cervix responds to a common tocolytic, nifedipine. Cervical slices from the internal os were treated with oxytocin alone or oxytocin + increasing doses of nifedipine to generate a dose response and half maximal inhibitory concentration. Student t test was used where appropriate.

RESULTS

Cervical tissue was collected from 41 women. Immunohistochemistry showed cervical smooth muscle cells at the internal and external os expressed mature smooth muscle cell markers and contraction-associated proteins. The cervix exhibited a gradient of cervical smooth muscle cells. The area of the internal os contained 50-60% cervical smooth muscle cells that were circumferentially organized in the periphery of the stroma, which may resemble a sphincter-like pattern. The external os contained approximately 10% cervical smooth muscle cells that were randomly scattered in the tissue. In organ bath studies, oxytocin stimulated the internal os to contract with more than double the force of the external os (1341 ± 693 vs 523 ± 536 integrated grams × seconds, respectively, P = .009). Nifedipine significantly decreased cervical tissue muscle force compared to timed vehicle control (oxytocin alone) at doses of 10(-5) mol/L (vehicle 47% ± 15% vs oxytocin + nifedipine 24% ± 16%, P = .007), 10(-4) mol/L (vehicle 46% ± 16% vs oxytocin + nifedipine -4% ± 20%, P = .003), and 10(-3) mol/L (vehicle 42% ± 14% vs oxytocin + nifedipine -15% ± 18%, P = .0006). The half maximal inhibitory concentration for nifedipine was 1.35 × 10(-5) mol/L.

CONCLUSION

Our findings suggest a new paradigm for cervical tissue morphology-one that includes the possibility of a specialized sphincter at the internal os. This new paradigm introduces novel avenues to further investigate potential mechanisms of normal and premature cervical remodeling.