Proteoglycan metabolism in the connective tissue of pregnant and non-pregnant human cervix. An in vitro study

Unrevealing functional candidate genes for bovine fertility through RNA sequencing meta-analysis and regulatory elements networks of co-expressed genes and lncRNAs

The high genetic heterogeneity and environmental effects of subfertility in livestock species make the elucidation of the genetic mechanisms associated with reproductive efficiency a difficult task. Network and co-expression network meta-analyses were applied alongside genetic variant calling and long non-coding RNA (lncRNA) characterization to identify functionally relevant target genes and regulatory subnetworks associated with fertility in dairy cattle. In total, 505 lncRNAs (441 previously annotated in the bovine reference genome ARS-UCD 1.2 and 64 novel lncRNAs) were identified. Seven differentially expressed genes between high-fertile (HF) and sub-fertile (SF) Holstein cows were identified in the network meta-analysis (CA5A, ENSBTAG00000051149, ENSBTAG00000003272, DEFB7, DIO2, TRPV3, and COL4A4). Additionally, seven functional candidate differentially co-expressed (DcoExp) modules with a differential regulatory pattern (|z-score|>2) were identified between HF and SF cows. The functional candidate genes and DcoExp modules identified were associated with fertility relevant processes such as the regulation of embryonic implantation and proliferation, interaction and molecule transfer between the fetus and the cow, and the immune system. These results help to better understand the genetic mechanisms associated with reproductive efficiency in dairy cattle through the identification of potential biomarkers and genetic variants associated with differentially expressed regulatory gene and lncRNAs regulatory element networks.

The Non-pregnant and Pregnant Human Cervix: a Systematic Proteomic Analysis

Appropriate timing of cervical remodeling (CR) is key to normal term parturition. To date, mechanisms behind normal and abnormal (premature or delayed) CR remain unclear. Recent studies show regional differences exist in human cervical tissue structure. While the entire cervix contains extracellular matrix (ECM), the internal os is highly cellular containing 50-60% cervical smooth muscle (CSM). The external os contains 10-20% CSM. Previously, we reported ECM rigidity and different ECM proteins influence CSM cell function, highlighting the importance of understanding not only how cervical cells orchestrate cervical ECM remodeling in pregnancy, but also how changes in specific ECM proteins can influence resident cellular function. To understand this dynamic process, we utilized a systematic proteomic approach to understand which soluble ECM and cellular proteins exist in the different regions of the human cervix and how the proteomic profiles change from the non-pregnant (NP) to the pregnant (PG) state. We found the human cervix proteome contains at least 4548 proteins and establish the types and relative abundance of cellular and soluble matrisome proteins found in the NP and PG human cervix. Further, we report the relative abundance of proteins involved with elastic fiber formation and ECM organization/degradation were significantly increased while proteins involved in RNA polymerase I/promoter opening, DNA methylation, senescence, immune system, and compliment activation were decreased in the PG compared to NP cervix. These findings establish an initial platform from which we can further comprehend how changes in the human cervix proteome results in normal and abnormal CR.

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.

Towards BirthAlert--A Clinical Device Intended for Early Preterm Birth Detection

Preterm birth causes 1 million infant deaths worldwide every year, making it the leading cause of infant mortality. Existing diagnostic tests such as transvaginal ultrasound or fetal fibronectin either cannot determine if preterm birth will occur in the future or can only predict the occurrence once cervical shortening has begun, at which point it is too late to reverse the accelerated parturition process. Using iterative and rapid prototyping techniques, we have developed an intravaginal proof-of-concept device that measures both cervical bioimpedance and cervical fluorescence to characterize microstructural changes in a pregnant woman's cervix in hopes of detecting preterm birth before macroscopic changes manifest in the tissue. If successful, such an early alert during this "silent phase" of the preterm birth syndrome may open a new window of opportunity for interventions that may reverse and avoid preterm birth altogether.

Preterm Cervical Ripening in humans

Preterm birth (PTB) is the leading cause of neonatal mortality and morbidity. Despite the current treatment procedures, the incidence of PTB has not changed in the past thirty years. Incomplete understanding of the biological and patophysiological mechanisms underlying preterm delivery is the major obstacle to prevent PTB. Cervical ripening is necessary for vaginal delivery and understanding of preterm cervical ripening is required for developing new treatment strategies. Several important substances such as HMGB1 and its receptors, CRH and its receptors and numerous cytokines are localized in the cervix and undergo distinct changes in labour. Other important -molecules, such as CRH, CRH-BP, CRH-R1, CRH-R2, HMGB1, TLR2, TLR4, IL-10, IL-12, are localized in the cervical epithelium, also indicating their role in the process of cervical ripening during labour. Furthermore, CRH stimulates IL-8 secretion from both preterm and term cervical fibroblasts. Recent studies from our group show that major -inflammatory changes occur in the cervix at labour irrespective of gestational age. This indicates that cervical ripening at both term and preterm is an inflammatory process even if no infection is present. However, preterm cervical ripening still entails some differences from term cervical ripening, for example in the down-regulation of mRNA expression of Toll-like receptors (TLR-2 and TLR-4) and IL-12, higher levels of IL-10 in cervical epithelium, and presents different secretion patterns of cervical fibroblasts. Moreover, preterm cervical ripening, like preterm delivery itself, is a multifactorial disorder with pathways which are partly different from those involved in PPROM and infected preterm labour.

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.

Relationships between mechanical properties and extracellular matrix constituents of the cervical stroma during pregnancy

In normal pregnancy, the cervix maintains its shape during a period of substantial fetal and uterine growth. Hence, maintenance of biomechanical integrity is an important aspect of cervical function. It is known that cervical mechanical properties arise from extracellular matrix (ECM). The most important constituent of the cervical ECM is fibrillar collagen-it is collagen protein that the cervix derives its "strength" from. Other matrix molecules known to affect the collagen network include water, proteoglycans, hyaluronan, and elastin. The objective of this review is to discuss relationships between biochemical constituents and macroscopic mechanical properties. The individual constituents of the ECM will be discussed, especially in regard to collagen remodeling during pregnancy. In addition, the macroscopic mechanical properties of cervical tissue will be reviewed. An improved understanding of the biochemistry of cervical "strength" will shed light on how the cervix maintains its shape in normal pregnancy and shortens in preterm birth.

Normal labor associated with changes in uterine heparan sulfate proteoglycan expression and localization

HYPOTHESIS

Proteoglycans are well-known modulators of intercellular communication and signaling. Remodeling of the proteoglycans in the human uterus occurs throughout pregnancy, and during labor. We therefore hypothesize that heparan sulfate proteoglycans (HSPGs) play an important role in establishing normal labor. In this study HSPGs were characterized and localized in human uterine tissue.

METHODS

Uterine biopsies were obtained from four nonpregnant women, four women during elective cesarean section and four during emergency cesarean section. The biopsies were extracted using 4 m guanidinium hydrochloride (GuHCL). HSPGs were then purified by repeated ion-exchange chromatography on dehydroepiandrosterone (DEAE)-cellulose after digestion with chondroitinase ABC and finally precipitated with Alcian blue. HSPGs were identified by agarose gel electrophoresis and Western blotting. Controlled degradation of the heparan sulfate (HS) side-chains was performed using heparitinase or deglycosylation with trifluoromethanesulfonic acid (TFMS). The resulting core proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and visualized by Coomassie staining. HSPGs were localized in uterine tissue by immunohistochemistry.

RESULTS

SDS-PAGE after deglycosylation indicated the presence of multiple distinct core proteins tentatively identified as syndecans 1-4 and glypican 1. Western blots confirmed the presence of these proteoglycans and also perlecan. Immunohistochemistry revealed that the HSPGs were localized mainly in the smooth muscle with few in the extracellular matrix (ECM). Syndecan 3, the dominant proteoglycan, showed the most pronounced changes during pregnancy and labor.

CONCLUSION

For the first time several heparan sulfate proteoglycans have been identified and localized in the human uterus and shown to vary in expression during pregnancy and labor. Syndecan 3 had the most outstanding features in this respect.

Thrombospondin 2 deficiency in pregnant mice results in premature softening of the uterine cervix

The gradual disorganization of collagen fibers in the stromal connective tissue of the uterine cervix is characteristic of progressive cervical softening during pregnancy. A lack of thrombospondin (TSP) 2 has been shown to be associated with altered collagen fibril morphology of connective-tissue-rich organs such as skin and tendon. The goal of this study was to determine the role of TSP2 in cervical softening by studying a TSP2-null mouse line. Creep testing showed that, in the nonpregnant animal and on Day 10 of pregnancy, there was no difference between the cervical extensibility of the wild-type and the TSP2-deficient mice. However, by Day 14 of pregnancy, the TSP2-null mice showed 4.5-fold increase in cervical extensibility, and by Day 18, a 6.1-fold increase, when compared with wild-type mice. A further indicator of compromised cervical integrity was that, on Days 14 and 18 of pregnancy, the cervix of TSP2-null mice broke rapidly under standard loading conditions that did not break the cervix of wild-type mice. Western blotting showed that TSP2 was expressed in the cervix of mice on Days 14 and 18 of pregnancy but not on Day 10 or in the nonpregnant animal. As determined by immunohistochemistry, the amount of matrix metalloproteinase 2 (MMP2) in the cervix of TSP2-null mice increased 11-fold on Day 14 of pregnancy and 19-fold on Day 18. Thus, TSP2-null mice provide an animal model to assist in the understanding of the molecular basis of spontaneous, premature softening of the uterine cervix.

Changes of the uterine proteoglycan distribution at term pregnancy and during labour

OBJECTIVE

To characterise uterine proteoglycans and changes therein during pregnancy and labour.

STUDY DESIGN

Uterine samples were collected from 6 non-pregnant, 10 term-pregnant and from 10 women in active labour. The proteoglycans were extracted by 4M guanidine hydrochloride and precipitated with Alcian Blue. They were separated by electrophoresis and identified by Western blotting.

RESULTS

Decorin was the dominating proteoglycan and smaller amounts of biglycan was found. A considerable amount of heparan sulphate proteoglycans was also detected. Decorin and biglycan decreased by 40% until term. The amount of heparan sulphate proteoglycans increased by 46% during active labour.

CONCLUSION

Our data indicate that a considerable remodelling of the uterine connective tissue occurs during pregnancy and labour. The decrease of decorin and biglycan and the increase of heparan sulphate proteoglycans may be important for normal myometrial contractions during labour.

Identification of the major proteoglycans from human myometrium

BACKGROUND

During pregnancy and parturition a remodeling within the extracellular matrix of the cervix and the corpus uteri occurs, which is of fundamental importance to a normal labor. The aim of this study is to identify the major proteoglycans in corpus uteri of non-pregnant subjects.

METHODS

From human uterine tissue proteoglycans were extracted and purified using CsCl-density gradient centrifugation, gel and ion-exchange chromatography. The proteoglycans were quantified and identified by Alcian Blue before and after ABC-digestion and by Western blotting.

RESULTS

The results showed that the corpus uteri contains a substantial amount of proteoglycans, 1.825 microg/mg wet weight. Decorin is dominating, constituting 63% of the total amount of proteoglycans. Heparan sulphate proteoglycans accounted for 20% and biglycan for 16%. Less than 1% consisted of the large proteoglycan versican.

CONCLUSIONS

Further investigations must be performed to provide more information of the biological role of the proteoglycans in the uterus, especially during labor, by the presence of heparan sulphate proteoglycans and the minute presence of versican which indicate that the proteoglycan composition and organization is different to that of the cervix.

Platelet-activating factor induces an imbalance between matrix metalloproteinase-1 and tissue inhibitor of metalloproteinases-1 expression in human uterine cervical fibroblasts

Platelet-activating factor (PAF) is involved in such reproductive processes as parturition. We investigated the effect of PAF on the expression of matrix metalloproteinase-1 (MMP-1) and that of tissue inhibitor of metalloproteinases-1 (TIMP-1) in human uterine cervical fibroblasts. Uterine cervical tissue was obtained from patients who underwent cesarean section at term. Collagenase-dispersed fibroblasts were cultured and used in the experiments. PAF receptor was identified in the uterine cervical fibroblasts by use of reverse transcription-polymerase chain reaction and Southern blot analysis. Northern blot analysis showed that PAF increased the expression of MMP-1 mRNA in a time-dependent manner, whereas expression of TIMP-1 mRNA was not affected by PAF. Concentration of MMP-1 protein in the PAF-treated culture media significantly exceeded that in control cultures. The PAF-induced production of MMP-1 protein was abolished by treatment with WEB 2170, a specific PAF receptor antagonist. Results suggest that PAF may accelerate collagenolysis in the human uterine cervix by inducing an imbalance in the activity between MMP-1 and TIMP-1, thus contributing to the cervical ripening during parturition.

Cadmium inhibits proteoglycan and procollagen production by cultured human lung fibroblasts

Chronic inhalation of cadmium at the workplace or in cigarette smoke is associated with emphysema, a disease characterized by extensive disruption of lung connective tissue. We have previously shown that cadmium, at noncytotoxic doses, inhibits fibroblast procollagen production in vitro, with maximal inhibitory effects of 69 +/- 6% (P < 0.01) at 30 &microM cadmium chloride (CdCl2). In this paper we show that at similar doses, cadmium also inhibits proteoglycan synthesis, with values reduced by between 36 +/- 4% (P < 0.01) and 42 +/- 6% (P < 0.01) for proteoglycans secreted into the culture media and associated with the cell layer, respectively. The greatest inhibition was obtained for the major matrix-associated proteoglycans, versican, decorin, and the large heparan sulfate proteoglycans, with synthesis values reduced by between 60 and 70%. Biglycan and other heparan sulfate proteoglycans were also affected, with synthesis values reduced by between 25 and 45%. In contrast, total protein synthesis was unaffected. Furthermore, effects of cadmium at the protein level were mirrored by reduction in messenger RNA levels for alpha1(I) procollagen, versican, and decorin. These data support the hypothesis that cadmium may play an important role in the pathogenesis of emphysema associated with chronic inhalation of cadmium fumes by inhibiting the production of connective tissue proteins.

Differential expressions of mRNA for proteoglycans, collagens and transforming growth factor-beta in the human cervix during pregnancy and involution

During pregnancy and involution, an extensive remodelling of the human cervical connective tissue occurs. This cervical ripening is one of the most pronounced physiological remodelling processes known in human connective tissue. To investigate how the remodelling is accomplished, the levels of mRNA for collagen I and III, versican and three small proteoglycans, biglycan, decorin and fibromodulin, were evaluated using Northern blots at different stages of cervical ripening. In the corresponding biopsies the concentration of collagen and of small and large proteoglycans were determined. The role of transforming growth factor-beta (TGF-beta) as a mediator of the remodelling process was also investigated. The concentration of collagen decreased and 1 week before partus, 50% of the nonpregnant level was attained. No further decrease was noted after partus. The mRNA for collagen I and III did, however, not decrease in the term pregnant cervix 1 week before partus. Only 20-30% decrease during the final ripening just before partus was recorded. Neither did the mRNA levels of the small proteoglycans change significantly during the ripening, despite an almost 50% decrease in the concentration of the small proteoglycans. The message for versican was, however, 5-fold increased at partus and then gradually returned to nonpregnant levels within 4 days after delivery. These changes corresponded to similar changes in the concentration of the large proteoglycan. Thus, the remodelling of the cervical connective tissue is achieved by two different mechanisms, on one hand an increased turnover of collagen and the small proteoglycans, on the other a changed transcription followed by an increased production of versican. During the involution 2- to 3-fold increases in the messages for collagen I and III, and the small proteoglycans, biglycan and decorin, corresponded to increases in the concentration of the small proteoglycans and non-extractable collagen. The message for TGF-beta was increased 2-fold immediately after delivery compared with the term pregnant state. Thus, TGF-beta may be of importance for the reconstruction of the cervix, which starts immediately after partus.

Cervical fetal fibronectin correlates to prostaglandin E2-induced cervical ripening and can be identified in cervical tissue

OBJECTIVE

Our purpose was to investigate whether prostaglandin E2-induced cervical ripening can be related to changes in fetal fibronectin levels and whether fetal fibronectin can be detected by immunohistochemistry in amniotic and cervical tissue.

STUDY DESIGN

Fetal fibronectin levels in cervical mucus were quantitated in 28 nulliparous term pregnant women with unfavorable cervical states before and after intracervical application of prostaglandin E2 gel. The concentration of fetal fibronectin was determined with use of an enzyme immunoassay. Cervical biopsy specimens and amniotic tissue for immunohistochemical analysis were obtained from three term pregnant women and after parturition in three women. Cervical biopsy specimens from two nonpregnant women served as controls. Immunohistochemical analysis was performed with antibodies directed toward fetal fibronectin.

RESULTS

The fetal fibronectin level in cervical mucus was low in all women before prostaglandin E2 application. In women with a successful prostaglandin E2-induced ripening (i.e., an increase of cervical score with > or =3 points), a tenfold increase in the fetal fibronectin level was registered. In women with an insufficient cervical ripening after prostaglandin E2 treatment no significant increase in the fetal fibronectin level was registered. The immunohistochemical analyses have identified fetal fibronectin in the epithelial cells of the cervix uteri.

CONCLUSION

Successful prostaglandin E2-induced cervical ripening seems to be related to a significant increase in cervical fetal fibronectin levels. Fetal fibronectin can be detected immunohistochemically in the pregnant human cervix.

Evidence for the presence of a large keratan sulphate proteoglycan in the human uterine cervix

Profound changes occur in the uterine cervix during pregnancy. In particular, the extracellular matrix of the connective tissue is remodelled extensively. To elucidate the mechanisms involved in this process, we have analysed the proteoglycan pattern in the human cervix from pregnant and non-pregnant women. Proteoglycans of the cervix tissue specimen were extracted with 4 M guanidine hydrochloride and precipitated with 80% ethanol. Purification of proteoglycans was performed by several chromatographic steps. Characterization of proteoglycans was done by SDS/PAGE before and after digestion with glycosaminoglycan-specific enzymes. Proteoglycans were detected by combined Alcian Blue/silver staining or, after blotting of biotin-labelled proteoglycans on to poly(vinylidene difluoride) membrane, with peroxidase-conjugated avidin or by the use of keratan sulphate- or decorin-specific monoclonal antibodies. In contrast with previous reports, where only chondroitin/dermatan sulphate proteoglycans have been found in the uterine cervix, we have shown in the present study the existence of a large keratan sulphate proteoglycan with an M(r) > 220,000 in cervix samples from non-pregnant and pregnant women. This proteoglycan showed a strong reaction with the keratan sulphate-specific monoclonal antibody 5D4 and could be degraded by keratanases. The size of the core protein of this keratan sulphate proteoglycan was estimated to be about M(r) 220,000.

Human Cart-1: structural organization, chromosomal localization, and functional analysis of a cartilage-specific homeodomain cDNA

Homeoproteins control cell fates during development, specifying pattern formation and the ontogeny of specific tissues and organs in embryogenesis. Cart-1 cDNA was recently cloned from a rat chondrosarcoma tumor and it encodes a protein containing a paired-like homeodomain that is selectively expressed in cartilage during early chondrocyte differentiation. Here we report the molecular cloning of the human Cart-1 cDNA from a HeLa cervical carcinoma cDNA library. The human Cart-1 cDNA sequence is 88% identical and the deduced amino acid sequence is 95% identical to the rat sequence, indicating that Cart-1 structure is highly conserved. Northern and reverse transcriptase polymerase chain reaction (RT-PCR) analysis revealed Cart-1 mRNA expression in HeLa cervical carcinoma cells and human cervical tissue, but Cart-1 mRNA was not detected in GH3 rat pituitary cells and murine 10T1/2 one-half fibroblast cells. The Cart-1 gene was localized to human chromosome 12 and regionally mapped to the 12q21.3-q22 by PCR analysis of rodent-X-human somatic cell hybrid DNA and the CEPH megabase-insert YAC DNA pools, respectively. The Holt-Oram syndrome, characterized by upper limb and atrial septal dysplasias, also maps to the 12q21.3-q22 region. Cotransfection studies show that Cart-1 inhibits the rat prolactin promoter and that this repression is mediated by footprint II, an AT-rich element that functions as an inhibitory site of prolactin gene expression in nonpituitary cells and which was used to clone Cart-1. Taken together, these data indicate that Cart-1 may also influence cervix development, identify a putative DNA binding site for Cart-1, and, begin to define its functional role as modulator of gene expression.

Cervical ripening in humans: potential roles of estrogen, progesterone, and insulin-like growth factor-I

OBJECTIVE

During pregnancy in humans a gradual connective tissue remodeling takes place in the cervix. The aim of this study was to examine a possible relationship between the action of gonadal steroids and growth factors and the biochemically identifiable changes in connective tissues during cervical ripening.

STUDY DESIGN

Cervical biopsy specimens and serum samples were taken from 20 term pregnant and 20 nonpregnant menstruating women. Estrogen receptors and progesterone receptors were measured with enzyme immunoassays. The messenger ribonucleic acid levels for estrogen receptors, progesterone receptors, and insulin-like growth factor-I were determined by solution hybridization with human complementary deoxyribonucleic acid probes. The concentration of collagen and its solubility by pepsin digestion were measured. Statistical evaluations were done with the Student t test.

RESULTS

In term pregnancy the estrogen receptor level decreased to 14% and the progesterone receptor level to 24% of nonpregnant levels (p <0.001 and p <0.01). The insulin-like growth factor-I messenger ribonucleic acid level increased 400% (p <0.01), whereas the messenger ribonucleic acid levels for estrogen receptors and progesterone receptors were unchanged. The changes coincided with a twofold decrease in collagen concentration (hydroxyproline) and a twofold increase in collagen solubility.

CONCLUSION

Estrogen receptors and progesterone receptors are present in human cervix. A significant down-regulation of estrogen receptors and progesterone receptors and a fourfold increase in the insulin-like growth factor-I messenger ribonucleic acid level were registered in term pregnant cervix. These findings coincided with the remodeling of the cervical connective tissue.

Biosynthesis of dermatan sulphate. Defructosylated Escherichia coli K4 capsular polysaccharide as a substrate for the D-glucuronyl C-5 epimerase, and an indication of a two-base reaction mechanism

The capsular polysaccharide from Escherichia coli K4 consists of a chondroitin ([GlcA(beta 1-->3)GalNAc(beta 1-->4)]n) backbone, to which beta-fructofuranose units are linked to C-3 of D-glucuronic acid (GlcA) residues. Removal of the fructose units by mild acid hydrolysis provided a substrate for the GlcA C-5 epimerase, which is involved in the generation of L-iduronic acid (IdoA) units during dermatan sulphate biosynthesis. Incubation of this substrate with solubilized fibroblast microsomal enzyme in the presence of 3H2O resulted in the incorporation of tritium at C-5 of hexuronyl units. A Km of 67 x 10(-6) M hexuronic acid (equivalent to disaccharide units) was determined, which is similar to that (80 x 10(-6) M) obtained for dermatan (desulphated dermatan sulphate). Vmax was about 4 times higher with dermatan than with the K4 substrate. A defructosylated K4 polysaccharide isolated after incubation of bacteria with D-[5-3H]glucose released 3H2O on reaction with the epimerase, and thus could be used to assay the enzyme. Incubation of a K4 substrate with solubilized microsomal epimerase for 6 h in the presence of 3H2O resulted in the formation of about 5% IdoA and approximately equal amounts of 3H in GlcA and IdoA. A corresponding incubation of dermatan yielded approx. 22% GlcA, which contained virtually all the 3H label. These results are tentatively explained in terms of a two-base reaction mechanism, involving a monoprotic L-ido-specific base and a polyprotic D-gluco-specific base. Most of the IdoA residues generated by the enzyme occurred singly, although some formation of two or three consecutive IdoA-containing disaccharide units was observed.

Interleukin-8 induces cervical ripening in rabbits

OBJECTIVE

The purpose of this study was to determine whether cervical ripening can be induced in rabbits by interleukin-8.

STUDY DESIGN

Nonpregnant and pregnant rabbits were treated for 5 days with vaginal suppositories containing 100 ng of interleukin-8. Collagen and glycosaminoglycan concentration in the cervices were assessed histologically by picrosirius red and alcian blue, and the mean optical density was calculated. The mean neutrophil count in five random fields was calculated from each biopsy specimen.

RESULTS

Interleukin-8 induced softening and dilatation of the rabbit cervices. Water content was significantly increased (p < 0.0001 and p < 0.001, respectively). Cervical collagen concentration was found to be significantly decreased (p < 0.0004 and p < 0.0001, respectively). Glycosaminoglycan concentration was significantly increased in nonpregnant and pregnant cervices (p < 0.0009 and p < 0.1, respectively). The mean number of neutrophils was significantly increased (p < 0.0005 and p < 0.006, respectively).

CONCLUSION

Interleukin-8 can induce cervical ripening in nonpregnant and pregnant rabbits.

Biomechanical analysis of cervix uteri in nonpregnant, pregnant and antigestagen (ZK 98 299) treated pregnant rats

The biomechanical properties of the cervix uteri of the rat were studied under different pharmacological conditions. Four groups of rats were enrolled: A. non-pregnant (N = 12), B. 18 days pregnant treated with vehicle (N = 14), C. 18 days pregnant treated with the antigestagen ZK 98 299 (Onapristone) for 19 hours (N = 15), D. 22 days pregnant during spontaneous labor (N = 12). Load-dimension curves of two 2 mm ring-preparations from each cervix were obtained by a material testing machine. The results showed that the sampling position, the cervical ripening process, and the influence of antigestagen treatment were reflected in the biomechanical and compositional parameters. In conclusion the methodology in the present study constitute a model in which the effect of pharmaca on cervical ripening can be tested. The study demonstrated that antigestagen treatment induced biomechanical changes in the cervix comparable to those occurring during physiological cervical ripening at term.

Proteoglycans and hyaluronan in female reproductive organs

Proteoglycans and hyaluronan have been isolated from various female reproductive organs and fetal membranes. Special attention has been directed to changes in the composition of these molecules in the tissue during pregnancy and ovulation. Various chondroitin sulfate/dermatan sulfate proteoglycans, which represent extracellular matrix proteoglycans, are closely related to the organization of connective tissues. Heparan sulfate proteoglycans are widely distributed on the plasma membrane of most mammalian cells including those in the female reproductive organs. They are involved in various aspects of cell-to-cell or cell-to-extracellular matrix interactions. Although the precise biological functions of these proteoglycans are not currently clear, recent advances in biochemistry and molecular biology techniques promise an exciting new development in this area.

Altered expression of small proteoglycans, collagen, and transforming growth factor-beta 1 in developing bleomycin-induced pulmonary fibrosis in rats

The development of bleomycin-induced pulmonary fibrosis in rats was studied over a period of 21 d after an intratracheal instillation of bleomycin. The expression of three small proteoglycans (biglycan, decorin, and fibromodulin), collagen III and TGF-beta 1 was studied by RNA-transfer blot analysis. The proteoglycans were also studied by SDS-polyacrylamide gel electrophoresis and Western blots. TGF-beta 1 mRNA increased threefold already on day 3 and remained elevated until day 10. After the increase of TGF-beta 1 mRNA the messages for biglycan and collagen III steadily increased to reach a maximum 10 d after bleomycin instillation. The mRNA for biglycan increased maximally fourfold and that of collagen III 2.5-fold. Decorin mRNA, in contrast to biglycan decreased and reached 20% of control on day 10. The message for fibromodulin remained constant throughout the study period. The amounts of biglycan and decorin in the tissue changed in accordance with the mRNA levels. The results corroborate and extend previous in vitro studies concerning the effect of TGF-beta 1 on the metabolism of small proteoglycans and show that these macromolecules are regulated differently also in vivo. The marked alterations of biglycan and decorin during the development of fibrosis suggests that these proteoglycans have a regulating role in this process.

Serum collagenase levels in relation to the state of the human cervix during pregnancy and labor

OBJECTIVE

The purpose of our study was to investigate the role of collagenase in the cervical ripening and dilatation process in term pregnancy.

STUDY DESIGN

Serum samples were obtained from nonpregnant women (n = 5) and term-pregnant women. The term-pregnant women were either admitted for elective cesarean section or labor induction (unfavorable cervix, n = 19; favorable cervix, n = 12) or in spontaneous, active labor (stiff and inelastic cervix, n = 7; soft compliant cervix, n = 8). Statistical analysis was performed with the Student t test.

RESULTS

The nonpregnant women had low serum collagenase levels (5.2 +/- 0.7 micrograms collagen digested per minute per 100 ml serum, mean +/- SEM). At term but before labor, women with unripe cervices had higher collagenase levels (10.3 +/- 0.9). The women with ripe cervices had even higher serum collagenase levels (22.9 +/- 4.2; p < 0.001). During labor, women with stiff and inelastic cervices had lower serum collagenase levels compared with women with soft and compliant cervices (12.9 +/- 1.7 vs 28.0 +/- 4.2; p < 0.01).

CONCLUSION

Serum collagenase during ripening at term and in active labor increases, supporting its active role in the ripening process.