Mechanism Of Cervical Ripening Research Articles

Characteristics of cervicovaginal microflora at different cervical maturity during late pregnancy: A nested case-control study.

The mechanism of cervical ripening in late pregnancy is still unclear. The vaginal microbiome has been reported to correlate with the preterm birth and short cervix in pregnant women. However, the associations between the cervical maturity and the vaginal microbiome are still poorly understood. We aim to analyze the cervicovaginal microflora in women with ripe cervix and in those who are unripe when delivering at term. Cervicovaginal swabs were collected between 40 and 41 weeks of gestation from the following 2 different groups of patients: ripe group (n = 25) and unripe group (n = 25). Samples were tested using 16S ribosomal RNA gene high-throughput sequencing and analyzed by bioinformatics platform. This study highlights the relationship between cervical maturity during late pregnancy and the composition of the cervicovaginal microflora. Both α- and β-diversity analyses demonstrated significant differences between women with a ripe cervix and those with an unripe cervix. Notably, the Lactobacillus profile was found to be closely linked to cervical maturity. There was a significant difference in the vaginal community state type, with CST IV being more prevalent in women with an unripe cervix. Furthermore, the association between CST IV and the unripe cervix group, as indicated by the odds ratio of 8.6, underscores its relevance in evaluating cervical maturity, when compared to other Lactobacillus-dominant community state types. Additionally, several bacterial taxa, particularly Lactobacillus, exhibited differential relative abundances between the two groups. This study provided significant evidence regarding the relationship between the vaginal microbiome and cervical maturity, highlighting the differential diversity, community state types, and specific bacterial taxa, such as Lactobacillus, that are associated with cervical maturation status. These findings contributed to our understanding of the dynamics of the cervicovaginal microflora during late pregnancy and its implications for cervical health.

Immunolocalization of Adipocytes and Prostaglandin E2 and Its Four Receptor Proteins EP1, EP2, EP3, and EP4 in the Caprine Cervix During Spontaneous Term Labor1

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.

Localization and steroid regulation of prostaglandin E2 receptor protein expression in ovine cervix

Although prostaglandin E2 (PGE2) has been identified as a central mediator of the cervical ripening process, the mechanisms responsible for PGE2 ripening are still poorly understood, partly because of the lack of information concerning the precise cellular localization and regulation of PGE2 (EP) receptors in the cervix. To provide new insights into the mechanisms of cervical ripening, we used indirect immunofluorescence to localize cervical EP receptor protein expression in ovariectomized ewes and examined the effect of administration of progesterone or estradiol. EP receptors were widely distributed in cervical blood vessels, epithelium of the cervical canal, circular and longitudinal muscles, and stroma. Estradiol replacement decreased EP1 and EP3 receptor protein in blood vessel media (by 23 and 31% respectively, P < 0.05) and decreased EP1 receptor protein expression in the longitudinal muscle layer (by 27%, P < 0.05). Stromal EP1 and EP3 receptor protein expression was also reduced by estradiol (by 29 and 20% respectively, P < 0.05). Progesterone replacement had no significant effect on EP receptor protein expression. The arterial changes would favor PGE2-induced vasodilatation, subsequent edema and leukocyte infiltration during the cervical ripening process whereas the muscular alterations would facilitate smooth muscle relaxation and cervical dilatation. Furthermore, estradiol provoked perinuclear localization of EP3 receptor protein in the longitudinal muscle layer. This latter result suggests that cellular EP receptor localization is regulated by estradiol and that PGE2 may also control smooth muscle contraction and regulate ovine cervical dilatation in an intracrine manner via EP3 receptors.

Decreased type I collagen expression in human uterine cervix during pregnancy.

To provide some insight into the mechanism of cervical ripening, the expression of type I collagen was investigated in human uterine cervical tissues obtained from the first (n = 4) and third (n = 3) trimesters of normal pregnancy. Indirect immunofluorescent staining was performed for type I collagen, and Northern blot analysis was done to assess expression of mRNA for the alpha1(I) chain. Collagens were also extracted from the human cervical tissues in the first and third trimesters of pregnancy. Immunohistochemical analysis revealed loose distribution of type I collagen in the uterine cervix of the first trimester compared with the third trimester of pregnancy. The relative levels of various collagens were evaluated by SDS-PAGE. The ratios of the intensity of the band of alpha1(I) to that of total collagen alpha1 chain in cervical tissues of the third trimester were significantly lower than those in cervical tissues of the first trimester of pregnancy (P < 0.05). In contrast, the ratios of the intensity of the band of alpha1(III) to that of total collagen alpha1 chain in cervical tissues of the third trimester were significantly higher than those in cervical tissues of the first trimester of pregnancy (P < 0.05). Northern blot analysis revealed that the cervical expression of mRNA for the alpha1(I) chain was significantly reduced in the third trimester compared with the first trimester of pregnancy (P < 0.01). These results suggest that type I collagen might play an important role in the maintenance of pregnancy and that decreased expression of this collagen could be associated with the process of uterine cervical ripening.

Lipopolysaccharide and pro-inflammatory cytokines induce expression of matrix metabolizing enzymes in human cervical smooth muscle cells-implication in the mechanism of cervical ripening

Lipopolysaccharide and pro-inflammatory cytokines induce expression of matrix metabolizing enzymes in human cervical smooth muscle cells-implication in the mechanism of cervical ripening

Collagenase activity in the human cervix uteri after prostaglandin E 2 application during the first trimester

Cervix biopsies were obtained during the first trimester from plurigravidae and primigravidae at various times after intracervical application of prostaglandin E 2. The tissues were extracted with Ca 2+-containing buffer, and collagenase activity was determined in these extracts using a solid phase assay in which triple helical 125I-labelled collagen was cleaved. Collagenase was detected in all samples but elevated activity was present only during a short temporal window after prostaglandin application. Maximal activity was observed 1 and 2 h after application of prostaglandin in multigravidae and 4 h in primigravidae. These data can explain why collagenase activity in cervical tissues after prostaglandin application had previously not been found. They indicate somewhat different mechanisms of cervical ripening in primigravide compared to multigravidae.