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

Inflammatory Amplification: A Central Tenet of Uterine Transition for Labor

In preparation for delivery, the uterus transitions from actively maintaining quiescence during pregnancy to an active parturient state. This transition occurs as a result of the accumulation of pro-inflammatory signals which are amplified by positive feedback interactions involving paracrine and autocrine signaling at the level of each intrauterine cell and tissue. The amplification events occur in parallel until they reach a certain threshold, ‘tipping the scale’ and contributing to processes of uterine activation and functional progesterone withdrawal. The described signaling interactions all occur upstream from the presentation of clinical labor symptoms. In this review, we will: 1) describe the different physiological processes involved in uterine transition for each intrauterine tissue; 2) compare and contrast the current models of labor initiation; 3) introduce innovative models for measuring paracrine inflammatory interactions; and 4) discuss the therapeutic value in identifying and targeting key players in this crucial event for preterm birth.

Regulation of MMP and TIMP expression in synovial fibroblasts from knee osteoarthritis with flexion contracture using adenovirus-mediated relaxin gene therapy

PURPOSE

The aim of this study was to investigate the effects of relaxin (RLN) expression on fibrosis inhibition in synovial fibroblasts.

MATERIALS AND METHODS

Tissue cells from patients with knee osteoarthritis and >30° flexion contractures were utilised. Synovial fibroblasts were activated by TGF-β1 (two nanograms per millilitre) and then exposed to Ad-RLN as a therapeutic gene, adenovirus-lacZ construct as a marker gene, and SB505124 as an inhibitor for TGF-β1 signal for 48 h. The mRNA expression levels of collagens and MMPs were analysed by reverse transcription-polymerase chain reaction. Also, fibronectin, phosphorylation of Smad2 and ERK1/2, alpha smooth muscle actin, TIMP-1, TIMP-2, MMP-1 and MMP-13 levels were estimated using western blotting, and the total collagen synthesis was assayed.

RESULTS

Ad-RLN-transduced synovial fibroblasts demonstrated 17%, 13%, and 48% reduction in collagen I, III and IV mRNA expression levels, respectively, and a 40% decrease in MMP-3, MMP-8, 20% decrease in MMP-9, MMP-13 mRNA expression, compared to non-Ad-RLN-transduced cells. In protein expression, Ad-RLN-transduced synovial fibroblasts demonstrated 46% increase in MMP-1, 5% decrease in MMP-2, 51% increase in MMP-9, and 22% increase in MMP-13, compared to non-Ad-RLN-transduced cells. Ad-RLN-transduced synovial fibroblasts showed a 25% decrease in TIMP-1 and 65% decrease in TIMP-2 protein expression at 48h, compared to non-Ad-RLN-transduced cells. Ad-RLN-transduced synovial fibroblasts demonstrated a 45% inhibition of fibronectin in protein expression level and 38% decrease in total collagen synthesis at 48h, compared to non-Ad-RLN-transduced cells.

CONCLUSION

Relaxin expression exerted anti-fibrogenic effects on synovial fibroblasts from patients with knee osteoarthritis and flexion contractures. Therefore, relaxin could be an alternative therapeutic agent during the initial stage of osteoarthritis with flexion contracture by exerting its anti-fibrogenic effects.

Topographic, tomographic and biomechanical corneal changes during pregnancy in patients with keratoconus: a cohort study

PURPOSE

This study aimed at evaluating the effect of pregnancy on topographic, tomographic and biomechanical parameters of patients with keratoconus (KC) in comparison with non-pregnant patients with KC.

METHOD

In a cohort study, patients with KC, whose disease was stable for at least 2 years, were evaluated before pregnancy, at their third trimester of pregnancy (34th week of pregnancy) and 6 months after pregnancy. As the control group, an equivalent number of age- and severity-matched non-pregnant female patients with KC were evaluated at the corresponding times. All subjects were evaluated with respect to central and thinnest corneal thickness (CCT and TCT), keratometry values, and maximum anterior and posterior elevation measurements (AE and PE) by Pentacam. Furthermore, corneal biomechanical properties including corneal hysteresis (CH) and corneal resistance factor (CRF) were measured using the ocular response analyser.

RESULTS

Twenty-two eyes of 11 patients were equally enrolled in each group. The results revealed that there was a statistically significant difference between the means of all measurements during the course of study (p < 0.001, repeated measures analysis of variance). The values of CCT, TCT, CH, CRF, IOPg and IOPcc were significantly decreased; however, keratometry values, AE, PE and refraction measurements were significantly increased during the study period (p < 0.001). In contrast, no significant differences were observed regarding the study variables in the control group (p > 0.05). According to the Amsler-Krumeich classification, severity of KC increased during the pregnancy and postpregnancy periods (p = 0.038).

CONCLUSION

The obtained results revealed that KC progressed during the pregnancy period and continued to the post-partum period, indicating that pregnancy may be a risk factor for KC progression. Patients with KC, who intend to become pregnant, may consider corneal cross-linking treatment in an attempt to stop KC progression.

Cervical strain determined by ultrasound elastography and its association with spontaneous preterm delivery

OBJECTIVE

To determine if there is an association between cervical strain, evaluated using ultrasound elastography, and spontaneous preterm delivery (sPTD) <37 weeks of gestation.

METHODS

One hundred and eighty nine (189) women at 16-24 weeks of gestation were evaluated. Ultrasound elastography was used to estimate cervical strain in three anatomical planes: one mid-sagittal in the same plane used for cervical length measurement, and two cross sectional images: one at the level of the internal cervical os, and the other at the level of the external cervical os. In each plane, two regions of interest (endocervix and entire cervix) were examined; a total of six regions of interest were evaluated.

RESULTS

The prevalence of sPTD was 11% (21/189). Strain values from each of the six cervical regions correlated weakly with cervical length (from r=-0.24, P<0.001 to r=-0.03, P=0.69). Strain measurements obtained in a cross sectional view of the internal cervical os were significantly associated with sPTD. Women with strain values ≤25th centile in the endocervical canal (0.19) and in the entire cervix (0.14) were 80% less likely to have a sPTD than women with strain values >25th centile [endocervical: odds ratio (OR) 0.2; 95% confidence interval (CI), 0.03-0.96; entire cervix: OR 0.17; 95% CI, 0.03-0.9]. Additional adjustment for gestational age, race, smoking status, parity, maternal age, pre-pregnancy body mass index, and previous preterm delivery did not appreciably alter the magnitude or statistical significance of these associations. Strain values obtained from the external cervical os and from the sagittal view were not associated with sPTD.

CONCLUSION

Low strain values in the internal cervical os were associated with a significantly lower risk of spontaneous preterm delivery <37 weeks of gestation.

The effect of relaxin on the musculoskeletal system

Relaxin is a hormone structurally related to insulin and insulin-like growth factor, which exerts its regulatory effect on the musculoskeletal and other systems through binding to its receptor in various tissues, mediated by different signaling pathways. Relaxin alters the properties of cartilage and tendon by activating collagenase. This hormone is also involved in bone remodeling and healing of injured ligaments and skeletal muscle. In this review, we have summarized the literature on the effect of relaxin in musculoskeletal system to provide a broad perspective for future studies in this field.

Pregnancy-induced Progression of Keratoconus in a 37-Year-Old Patient

Purpose

To report a case of keratoconus that progressed during pregnancy without any accompanying disease.

Methods

A case report.

Results

A patient with keratoconus that worsened during pregnancy demonstrates that pregnancy can be a previously unrecognized risk factor for progression of keratoconus.

Conclusion

To our knowledge, this is the first case reported in Brazil and the third paper in the world showing pregnancyinduced keratoconus progression in a patient with no accompanying disease.

How to cite this article

Glicéria J, Valbon BF, Santos RT, Ambrósio R Jr. Pregnancy-induced Progression of Keratoconus in a 37-Year-Old Patient. Int J Kerat Ect Cor Dis 2013;2(2):84-88.

Serum relaxin levels affect the in vivo properties of some but not all tendons in normally menstruating young women

Relaxin (hRLX) is a hormone reported to affect collagen synthesis. Its effects are also thought to be modulated by other sex hormones, including oestrogen, which has previously been found to be associated with alterations of in vivo tendon properties. There is thus a potential for hRLX to impact on collagen, which could result in tendon structural and mechanical properties being modified. The present study therefore aimed to determine any interaction between hRLX and tendon stiffness, in normally menstruating women (n = 12). Tendon properties were determined using a combination of dynamometry and B-mode ultrasound, whilst serum hRLX levels were established by ELISA. Serum hRLX level was seen to be negatively associated with patellar tendon stiffness (r = -0.56; P < 0.001), explaining 31% of the variance in this parameter. There was no association between hRLX and gastrocnemius tendon stiffness (P > 0.05), or with the cross-sectional area of either of the two tendons (P > 0.05). In young, normally menstruating women, hRLX appears to have a significant effect on the patellar but not the gastrocnemius tendon stiffness. Where it has an effect, this appears to be on the intrinsic properties rather than on the dimensions of said tendon. Future work to elucidate the physiological cause of this selectivity in the impact of relaxin will be key to mapping the impact of the endocrine system on the phenotype of tendinous tissue.

The effect of relaxin on the female anterior cruciate ligament: Analysis of mechanical properties in an animal model

BACKGROUND

The peptide hormone relaxin, found in pregnant and non-pregnant females, has been shown to have collagenolytic effects on ligamentous tissue. Relaxin receptors have recently been identified on the human female anterior cruciate ligament (ACL). Relaxin may affect the load bearing properties of the female ACL and contribute to non-contact ACL injuries.

HYPOTHESIS

The administration of recombinant relaxin+/-estrogen will lead to a significant decrease in ACL integrity in the guinea pig model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Adult female guinea pigs were divided into three experimental groups. Group 1 (n=4) was administered only 20 microg/h of recombinant porcine relaxin for 3 weeks. Group 2 (n=4) was administered 20 microg/h of recombinant porcine relaxin and 5 microg/h of estradiol for 3 weeks. Group 3 (n=4) served as both a normal control before surgical transection of the ACL and a positive ACL tear control after transection. All hormones were administered using separate implanted osmotic pumps. ACL laxity was tested by implanting radio-opaque markers in the femur and tibia of each leg. After applying a standard anterior force (22 N), the distance between markers was measured radiographically at day 0 and day 21. The animals were then sacrificed and the ACL's were analyzed for load-to-failure using a material testing machine.

RESULTS

Load-to-failure testing indicated that animals treated with relaxin only had significantly weaker ACL's (micro=40.4 N, p=0.001) compared to controls (micro=64.1 N). The relaxin+estrogen group (micro=32.7 N) was also significantly weaker than controls (p=0.007). There were no statistical differences between relaxin and relaxin+estrogen groups. Both relaxin only and relaxin+estrogen groups showed an increase in anterior translation of the tibia after 3 weeks of infusion, but it did not achieve statistical significance.

CONCLUSIONS

Relaxin significantly alters the mechanical properties of the ACL in an animal model.

CLINICAL RELEVANCE

The effects of relaxin, possibly in conjunction with estrogen, may contribute to a comprehensive etiology for human female non-contact ACL injuries.

Mechanisms of Relaxin-Mediated Premature Birth

In women, circulating relaxin is produced by the corpus luteum of pregnancy. The levels of relaxin are predominantly determined by the luteal mass, the number of corpora lutea present. Relaxin levels are highest after ovulation induction, which stimulates formation of many corpora lutea. Elevated relaxin levels in the first trimester of pregnancy are maintained throughout pregnancy and are linearly related to preterm birth. In an in vitro model of late human pregnancy cervix, relaxin increases MMP-1 and MMP-3 and decreases TIMP-1 levels, thus acting as a positive regulator of matrix metalloproteinases. In an in vivo rhesus monkey model of early pregnancy, relaxin decreases cervical collagen content, decreases cervical lumican levels, and stimulates MMP-7 levels. Early effects of relaxin in the uterus include increasing endometrial arteriole number and increasing the number of leukocytes, uterine natural killer cells, macrophages, and neutrophils. These cells release many cytokines which contribute to changes that stimulate and facilitate uterine contractility. If these changes persist in late pregnancy, relaxin may be a mediator of labor. Excess relaxin may produce these changes at an accelerated rate, causing preterm birth.

Are alterations in plasma protease concentrations during labor associated with poor obstetric outcomes?

OBJECTIVE

The purpose of this study was to assess the association between abnormal connective tissue remodeling during labor as reflected by plasma concentrations of extracellular matrix remodeling proteolytic enzymes and adverse obstetric outcomes.

STUDY DESIGN

A prospective observational study of 176 nulliparous women who attended the antenatal clinics at the Mercy Hospital for Women (Melbourne, Australia) from 1999 to 2000.

RESULTS

Patients with a prolonged second stage (>120 minutes) had a significantly increased plasma concentration of matrix metalloproteinase 9 after delivery compared with control subjects (P<.001); patients in labor who underwent an emergency caesarean delivery had a significantly lower concentration (P<.001). Patients with a prolonged duration of labor (>11 hours) had a significantly lower urokinase plasminogen activator plasma concentration compared with control subjects (P<.01).

CONCLUSION

Altered plasma concentrations of extracellular matrix remodeling proteolytic enzymes, matrix metalloproteinase 9, and urokinase plasminogen activator were found to be associated with abnormal labor and delivery outcomes. This finding may provide a useful predictor of abnormal obstetric outcomes.

Effects of selective and nonselective PGE2 receptor agonists on cervical tensile strength and collagen organization and microstructure in the pregnant rat at term

OBJECTIVE

The purpose of this study was to determine which of the 4 PGE2 receptors (EP1-EP4) is involved in cervical ripening in the rat, and to correlate its activity with changes in tensile strength and collagen microstructure.

STUDY DESIGN

We assessed tensile strength after administration of selective and nonselective PGE2 receptor agonists. Quantification of collagen organization and microstructure was accomplished with polarized light microscopy and transmission electron microscopy.

RESULTS

Selective agonists for EP1-3 did not produce significant differences when compared with each other or control animals. Significant differences in tensile strength, proportion of organized collagen, and microstructure were found between treatment and control animals with the nonselective receptor agonist (PGE2). This was taken as an indirect measure of EP4 activity.

CONCLUSION

Changes in cervical collagen organization and microstructure are quantifiable and correlate with changes in tensile strength. These data implicate EP4 as the PGE2 receptor involved in producing these changes in the rat cervix.

Prostaglandins and the myometrium and cervix

Prostaglandins have long been thought to play important roles in the mechanism of parturition. Here we review the involvement of prostaglandins in myometrial and cervical functions with emphasis on human labor and birth. In addition, the cellular sources of prostaglandins as well as their interactions with various other endocrine, paracrine and physical factors, such as oxytocin, corticotropin releasing hormone, nitric oxide, platelet activating factor, cytokines, endothelin and stretch are also addressed together with their potential role in the molecular reorganization of cervical structure associated with labor and delivery. Finally, the premier role of progesterone in pregnancy maintenance and parturition is juxtaposed with the proposed "fine-tuning", modulatory role of prostaglandins and the above listed factors in the regulation of parturition.

Changes in water content, collagen degradation, collagen content, and concentration in repeated biopsies of the cervix of pregnant cows

The objective of the present study was to assess if cervical ripeness could be quantified by measuring the percentage of denaturation of the collagen network of the stromal layer. Biopsy specimens from the caudal part of the cervix were obtained from nine pluriparous cows between Days 149 and 157 of gestation (second-trimester biopsy), at exactly Day 275 of gestation (term biopsy), and shortly after calving (calving biopsy). The samples were divided into a superficial stromal part and a deep stromal part. The water content was derived from the weight of the samples before and after lyophilization. A colorimetric assay was used to assess the percentage of collagen denaturation by determining the extinction at 570 nm of hydroxyproline released from alpha-chymotrypsine-treated samples. By incorporating a hydroxyproline standard series in the measurements, the insoluble collagen content (mug/mg dry wt) as well as the insoluble collagen concentration (mug/mg wet wt) could be derived. The water content of both layers of the cervix significantly increased between midpregnancy and parturition (P < 0.01). The insoluble collagen content and the insoluble collagen concentration were significantly increased at term (P < 0.01 and P < 0.05, respectively) but were significantly decreased at calving (P < 0.05 and P < 0.01, respectively). Both parameters showed no significant differences between the superficial and deep stromal layer, and they were significantly correlated with each other. A significant increase in the percentage denaturation of the deep stromal layer occurred between the second trimester and term pregnancy (P < 0.01), whereas at calving, the percentage denaturation had not significantly increased compared to term. The percentage of collagen denaturation of the superficial stromal layer did not significantly change with stage of gestation or at parturition. Our findings indicate that cervical ripening is a combination of increased collagen synthesis and increased percentage of collagen denaturation, whereas at calving, an increased digestion of the denatured collagen leads to increased collagen loss from the cervical connective tissue. The finding that cervical ripening mainly takes place in the deep stromal layer of the cervix emphasizes the importance of a detailed description of the tissue sampling sites for a proper interpretation of the results obtained from biochemical studies of the cervix.

Relaxin receptors in the human female anterior cruciate ligament

BACKGROUND

Noncontact anterior cruciate ligament injuries occur two to eight times more often in women than in men. Changes in ligament laxity and strength have been associated with female hormones such as relaxin.

HYPOTHESIS

Relaxin receptors are present within the female anterior cruciate ligament.

STUDY DESIGN

Controlled laboratory study.

METHODS

Remnants of anterior cruciate ligament were harvested from five women and five men undergoing routine ligament reconstruction. Relaxin was biotinylated and analyzed for biologic activity with use of the mouse interpubic ligament bioassay. Immunohistochemical localization of relaxin receptors was performed with appropriate negative controls and competitive binding assays to determine receptor specificity and saturability.

RESULTS

Anterior cruciate ligament sections from women but not from men showed uniform specific binding that was limited to synovial lining cells, stromal fibroblasts, and cells lining blood vessels. Specific binding was confirmed in the presence of a 2000-fold excess of human insulin, the structural homolog of relaxin, and competitive inhibition was demonstrated in the presence of a 2000-fold excess of unlabeled relaxin.

CONCLUSIONS

Relaxin exhibits specific saturable binding in the female anterior cruciate ligament, where specific relaxin receptors were present.

CLINICAL RELEVANCE

The high incidence of anterior cruciate ligament rupture in female athletes may be partially explained by the effects of relaxin.

Relaxin positively regulates matrix metalloproteinase expression in human lower uterine segment fibroblasts using a tyrosine kinase signaling pathway

Despite the importance of relaxin to normal parturition in various species and its potential as an etiological agent in preterm delivery in women, knowledge regarding the mechanisms by which relaxin alters cervical connective tissue is extremely limited. An established in vitro model for human pregnancy cervix, human lower uterine segment fibroblasts, was used to determine the effects of relaxin as well as those of progesterone on the expression of matrix metalloproteinases and tissue inhibitor of metalloproteinase-1. The results demonstrate that relaxin is a positive regulator of matrix metalloproteinase expression, as it stimulates the expression of procollagenase protein and mRNA levels, stimulates prostromelysin-1 protein and mRNA levels, and inhibits tissue inhibitor of metalloproteinase-1 protein expression. Stimulation of procollagenase and prostromelysin-1 expression by relaxin does not involve phorbol-12-myristate-13-acetate- sensitive PKCs. Relaxin-stimulated tyrosine phosphorylation of the putative receptor and inhibition by a receptor tyrosine kinase inhibitor suggest that the relaxin receptor is probably a tyrosine kinase receptor. Inhibition of c-Raf protein expression using an antisense oligonucleotide inhibits relaxin regulation of matrix metalloproteinase and tissue inhibitor of metalloproteinase-1, suggesting that a signaling pathway involving c-Raf kinase mediates relaxin action.

Collagenolysis in the lower uterine segment during parturition at term: correlations with stage of cervical dilatation and duration of labor

OBJECTIVE

The objective of this study was to quantify the extent of neutrophil infiltration and the concentrations of enzymes involved in collagenolysis in the lower uterine segment in relation to the degree of cervical dilatation and the duration of labor.

STUDY DESIGN

Biopsy specimens of the lower uterine segment were obtained from 62 women undergoing cesarean section at term. The number of extravascular neutrophils was assessed with enzyme histochemical evaluation, and the concentrations of matrix metalloproteinase-8, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 by were assessed by enzyme-linked immunosorbent assay.

RESULTS

The neutrophil count and the concentrations of matrix metalloproteinase-8, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 increased with increasing cervical dilatation. At >6 cm the neutrophil count and the concentrations of matrix metalloproteinase-8, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 were significantly higher than at <2 cm. An association with the duration of labor was found for the neutrophil count and the concentrations of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinases-1. Multiple linear regression analysis showed that the degree of cervical dilatation is more closely related to the 4 laboratory parameters investigated than to the duration of labor.

CONCLUSION

The findings support the hypothesis that local changes (ie, collagenolysis) in the lower uterine segment unrelated to uterine activity play a crucial role in cervical dilatation at term.

Changes in the cervical extracellular matrix during pregnancy and parturition

The key function of the uterine cervix to maintain pregnancy is biochemically characterized by an increased synthesis of proteins (e.g., collagen), proteoglycans, and glycoproteins (e.g., fibronectin) as well as by defined interactions between these components of the extracellular matrix. In contrast to the slow phase of the cervical ripening process in late pregnancy, cervical dilatation during parturition requires the rapid production and action of catabolic enzymes leading mainly to collagen degradation and changes in its architecture but also to degradation of other fundamental matrix proteins. Evidence suggests that an increased production of TNF-alpha and IL-1 beta, e.g., induces a rise in the expression of endothelial adhesion molecules with subsequent extravasation of neutrophils into the cervical stroma and that the chemotaxis and degranulation of these cells is triggered by an increased concentration of IL-8. Rising concentrations of hyaluronan at this time have been considered as potent inducers of IL-1 beta and TNF-alpha synthesis by various leukocyte populations. The increase in IL-6 synthesis stimulates prostaglandin and leukotriene production causing dilatation of cervical vessels and further promoting the extravasation of leukocytes. The proteases released after degranulation of neutrophils encounter an already destabilized collagenous fiber network. Since a sustained action of proteases may lead to severe tissue damage, this process is strictly limited in time and is controlled by increasing concentrations of tissue inhibitors of protease in the lower uterine segment immediately after delivery. The clinical consequences of this basic research is to develop new concepts in a more causal treatment of cervical pathology during pregnancy and parturition.

Mechanisms of full-term and preterm labor: factors influencing uterine activity

OBJECTIVE

To review factors influencing uterine activity leading to delivery.

DATA SOURCES

A search was conducted on MEDLINE and CINAHL under the terms "preterm labor," "preterm delivery," and "physiology of labor and preterm labor."

STUDY SELECTION

One-hundred fifty articles were reviewed, with selection based on physiologic concepts judged to be most relevant to nursing practice.

DATA SYNTHESIS

In this review, factors initiating labor and preterm labor (PTL) are identified, along with areas for further research.

CONCLUSIONS

Despite research on what initiates labor, it is unknown how the various mechanisms are integrated. Nurses are in a position to conduct research to help further the understanding of the labor and PTL processes. Nurses can use their assessment skills to help identify women at risk for PTL and delivery.

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.

Demonstration of a relaxin receptor and relaxin-stimulated tyrosine phosphorylation in human lower uterine segment fibroblasts

To elucidate the mechanism of relaxin action, we studied the binding characteristics of human relaxin and its effects on intracellular concentrations of cAMP and tyrosine phosphorylation of cellular proteins in a model system of human cervix, human lower uterine segment fibroblasts. Human relaxin labeled with 125I bound specifically to a single class of high-affinity relaxin binding sites, distinct from insulin receptors, with a mean (+/-SEM) dissociation constant (Kd) of 4.36 +/- 1.7 x 10(-9) M and a mean of 3220 +/- 557 binding sites per cell in human lower uterine segment fibroblasts. Relaxin, in quantities that were shown previously to stimulate intracellular levels of cAMP in other cell types, had no effect on intracellular levels of cAMP in human lower uterine segment fibroblasts even in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methyl-xanthine (IBMX). Incubation of the cells with relaxin caused a significant increase in tyrosine phosphorylation of a protein with an apparent Mr of approximately 220 kDa in these cells. In concert with results of recent studies that demonstrated that the Mr of the relaxin receptor is approximately 220 kDa, our data suggest that the phosphorylated protein is likely to be the relaxin receptor.

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.

Tissue-specific expression of the relaxed conformation of plasminogen activator inhibitor-2 and low-density lipoprotein receptor-related protein in human term gestational tissues

The relaxed conformation of plasminogen activator inhibitor-2 (PAIr) is formed during inactivation of the matrix-degrading enzyme urokinase plasminogen activator (uPA). The presence of PAIr in tissues, therefore, indicates the in situ inhibition of uPA-mediated proteolysis. In addition, PAIr functions as a ligand for the clearance receptor low-density lipoprotein receptor-related protein (LRP), thereby promoting internalization of receptor-bound uPA-PAIr complexes from the cell surface. The rapid internalization of receptor-bound, inactivated uPA has been suggested to be characteristic of invasive cell phenotypes. The aims of this study were to characterize the immunohistochemical localization of PAIr in human term gestational tissues (amnion, choriodecidua, and placenta) and to establish its co-expression with other components of the uPA cascade. The results obtained indicate that PAIr immunoreactivity was exclusively localized to amnion epithelial cells, with only minimal staining in the underlying chorion. PAIr immunoreactivity was not detectable in any of the trophoblastic tissues examined (villous and extravillous). The tissue-specific expression of PAIr immunoreactivity was not significantly altered in association with labor onset. uPA and PAI-2 staining was localized predominantly to amnion epithelial cells, underlying chorion, and trophoblast cells of villous and extravillous tissue. Amnion and trophoblasts of extravillous and chorionic tissue showed uPAR immunoreactivity, whereas staining in placenta was absent. Immunoreactive LRP was confined to trophoblasts of the chorion, and the villous and extravillous tissue. For the first time, localization of PAIr at the tissue level has been identified. The data obtained are consistent with the hypothesis that cells of invasive phenotype, although expressing all components of the uPA cascade, do not accumulate immunoreactive PAIr, because it is rapidly internalized from the cell surface. Conversely, cells of noninvasive phenotype will accumulate PAIr immunoreactivity only in the absence of LRP expression. We propose that the presence of PAIr and the absence of LRP at the cell surface are putative markers of noninvasive phenotypes.

Regulation of decidual cell chemokine production by group B streptococci and purified bacterial cell wall components

OBJECTIVE

Our purpose was to determine whether cultured human decidual cells produce chemokines in response to different strains of group B streptococci and purified bacterial cell wall components.

STUDY DESIGN

Human decidual cells were cultured from term placentas by standard techniques. Different strains of group B streptococci were isolated from neonates with early-onset group B streptococci sepsis. Confluent cell monolayers were incubated with these different strains of group B streptococci and various concentrations of purified bacterial cell wall components (including lipoteichoic acid, sialic acid, lipopolysaccharide, and lipid A) for 16 hours at 37 degrees C. Culture supernatants were collected and assayed for macrophage inflammatory protein-1 alpha and interleukin-8. Statistical analysis was by analysis of variance.

RESULTS

We found that cultured human decidual cells produced significant amounts of the two chemokines macrophage inflammatory protein-1 alpha and interleukin-8 in a strain-specific fashion to the various different strains of group B streptococci tested, from 215% to 421% over baseline production (p < 0.05 by analysis of variance). Also, we found that incubation of decidual cells with various concentrations of lipoteichoic acid, sialic acid, lipopolysaccharide, and lipid A resulted in significant concentration-dependent increases in decidual cell macrophage inflammatory protein-1 alpha and interleukin-8 production (p < 0.05.)

CONCLUSIONS

Decidual cells produced significant amounts of the chemokines macrophage inflammatory protein-1 alpha and interleukin-8 in response to intact group B streptococci in a strain-specific fashion and in response to various concentrations of different bacterial cell wall components. Because chemokines are important mediators signaling migration of different immune effector cells into areas of inflammation, we suggest that decidual cell chemokine production in response to bacteria and bacterial cell wall components may be a key early event in the pathogenesis of infection-associated preterm labor.

Interleukin-8 is a mediator of the final cervical ripening in humans

OBJECTIVE

The aim of the present study was to investigate the presence of interleukin-8 (IL-8) in the human cervix and whether the levels of interleukin-8 could be related to the ripening process during pregnancy.

STUDY DESIGN

Cervical biopsies were obtained in twelve term pregnant and in eight vaginally delivered women. Seven non-pregnant fertile women served as controls. After homogenisation and centrifugation, IL-8 levels were determined in the supernatant by an enzyme-immunoassay (EIA).

RESULTS

In women at term, the concentration of IL-8 increased six-fold from median 330 pg/ml to median 2190 pg/ml (P < 0.001). After the final cervical ripening it increased in additional 11-fold to median 26,100 pg/ml (P < 0.001). These changes are highly significant.

CONCLUSION

To our knowledge, this is the first time IL-8 has been identified in human cervix. Our results support the involvement of IL-8 in the connective tissue remodelling during the final cervical ripening just before onset of labour.

Preinduction cervical ripening: a randomized prospective comparison of the efficacy and safety of intravaginal and intracervical prostaglandin E2 gel

OBJECTIVE

The purpose of this study was to compare the effectiveness and safety of vaginally administered 5 mg prostaglandin E2 gel prepared in our hospital pharmacy with a commercially available 0.5 mg intracervical prostaglandin E2 gel.

STUDY DESIGN

Eighty-three patients undergoing labor induction were randomly assigned to one of two groups for cervical ripening. Either a preparation of 5 mg of prostaglandin E2 was placed vaginally or a commercially available 0.5 mg of prostaglandin E2 was placed intracervically. A maximum of three doses at 6-hour intervals was administered before oxytocin was begun.

RESULTS

Among the 83 patients evaluated, 44 were given vaginal gel and 39 were given intracervical gel. No statistically significant differences were observed between the two treatment groups with respect to the incidence of spontaneous versus induced labor, need for oxytocin augmentation, gel-to-induction interval, Bishop score change, maximum oxytocin dose, maximum dilatation rate, length of labor, cesarean section rate, fetal Apgar scores, fetal umbilical vein pH, or fetal umbilical artery pH.

CONCLUSIONS

The two prostaglandin E2 formulations appear equivalent in efficacy and safety. Constraints placed on intracervical prostaglandin E2 gel make the vaginal preparation a desirable choice.

Regulation of cultured human chorion cell chemokine production by group B streptococci and purified bacterial products

PROBLEM

To determine if different strains of group B streptococci (GBS) and purified bacterial products regulate chemokine production by cultured human chorion cells.

METHOD OF STUDY

Primary cultures of human chorion cells were established from placentae isolated from normal women at term gestation having repeat cesarean section. Five different strains of heat-killed GBS were incubated with confluent chorion cells at 10(7) bacteria/ml for 16 hours at 37 degrees C. In separate experiments, lipoteichoic acid and sialic acid at various concentrations were incubated with chorion cells for 16 hours at 37 degrees C. Culture supernatants were collected and then assayed to determine concentrations of interleukin-8 (IL-8) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) by ELISA.

RESULTS

We found that GBS stimulated chorion cell production of MIP-1 alpha in a strain-specific fashion. We also found that both lipoteichoic acid and sialic acid stimulated concentration-dependent increases in chorion cell IL-8 production. Chorion cells, however, did not increase MIP-1 alpha production in response to either lipoteichoic acid or sialic acid. Two strains of GBS tested induced concentration-dependent increases in both IL-8 and MIP-1 alpha, but both stimulated IL-8 production to a greater extent. Similarly, IL-1 beta also caused chorion cells to produce more IL-8 than MIP-1 alpha.

CONCLUSIONS

Our data are the first to show that GBS and purified bacterial products can stimulate chemokine production by fetal gestational tissues. We suggest that chorion cells may produce specific types of chemokines to attract different types of inflammatory cells and thus may participate in the pathophysiology of infection-mediated preterm labor by directing specific inflammatory responses.

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.

Collagenase: a key enzyme in collagen turnover

The primary agents responsible for cartilage and bone destruction in joint diseases are active proteinases that degrade collagen and proteoglycan. All four main classes of proteolytic enzymes are involved in either the normal turnover of connective tissue or its pathological destruction. These proteinases are made by different cells found within the joints. Both extracellular and intracellular pathways exist and individual enzymes can be inhibited by specific proteinaceous inhibitors that block their activity. Recent research has implicated the matrix metalloproteinases (MMPs) in many of the processes involved in joint diseases. The metalloproteinases are capable of degrading all components of the extracellular matrix. This family of proteinases contains a group of at least three collagenases that are capable of degrading native fibrillar collagen. Collagen degradation within joint disease is recognized as the irreversible step in the destruction of cartilage that leads to a failure in joint function. The collagenases are the enzymes necessary to initiate collagen turnover in normal connective tissue turnover and in disease.

Metalloproteinase inhibitors and the prevention of connective tissue breakdown

The primary agents responsible for cartilage and bone destruction in joint diseases are active proteinases degrading collagen and proteoglycan. All four main classes of proteolytic enzymes are involved in either the normal turnover of connective tissue or its pathological destruction. These proteinases are made by different cells found within the joints. Both extracellular and intracellular pathways exist, and individual enzymes can be inhibited by specific proteinaceous inhibitors that block their activity. Recent research has implicated the matrix metalloproteinases in many of the processes involved in joint diseases. Conventional treatments do little to affect the underlying disease processes, and recently, the use of proteinase inhibitors has been suggested as a new therapeutic approach. A large variety of different synthetic approaches have been used and highly effective metalloproteinase inhibitors have been designed, synthesised and tested. These metalloproteinase inhibitors can prevent the destruction of animal cartilage in model systems and slow the progression of human tumours. Future patient trials will test the effectiveness of these compounds in vivo for the treatment of joint diseases.

Cervical ripening before medical induction of labor: a comparison of prostaglandin E2, estradiol, and oxytocin

OBJECTIVE

Our purpose was to evaluate the effectiveness of oxytocin, prostaglandin E2 intracervical gel, and estradiol cream for ripening the very unfavorable cervix in patients requiring induction of labor at term.

STUDY DESIGN

This prospective, randomized study was conducted in a population of women with a very unfavorable cervix (Bishop score < 4) requiring induction of labor. The patients received prostaglandin E2 gel (0.5 mg) intracervically (three doses 6 hours apart), 4 mg estradiol cream in the anterior fornix of the vagina (three doses 6 hours apart), or oxytocin at induction per protocol with an infusion pump.

RESULTS

Ninety-nine women were recruited into this trial and evenly distributed among the three groups. The demographics of maternal age, race, parity, gestational age, initial Bishop score, and indication for induction were similar among the groups. The incidence of cesarean deliveries was similar in the three groups with approximately 59% of pregnancies delivered abdominally. For patients undergoing abdominal delivery the maximum cervical dilatation among the oxytocin, estradiol, and prostaglandin E2 groups was similar (3.90 +/- 3.02 cm, 3.63 +/- 2.79 cm, and 4.65 +/- 2.78 cm, respectively; p > 0.05). For all patients birth weight and Apgar scores at 1 and 5 minutes were comparable across all regimens (p > 0.05). In the subset of patients delivered vaginally patients receiving oxytocin for cervical ripening had the greatest improvement in Bishop score over baseline (p = 0.023) with an improvement of 7.08 +/- 2.42.

CONCLUSION

No differences were detected among prostaglandin E2 gel, estrogen, and oxytocin in relation to cervical ripening in patients with an unfavorable cervix at term who require an induction of labor. Patients with a very unfavorable cervix at term who require delivery may benefit from serial ripening and inductions.

Tissue collagenase: serum levels during pregnancy and parturition

Serum levels of tissue collagenase, matrix metalloproteinase-1, were measured in both longitudinal and cross-sectional studies, in 332 pregnant women and 27 non-pregnant volunteers. The enzyme-linked immunosorbent assay (ELISA) used is the first described to measure collagenase in serum directly, is specific, and is rapid and reproducible. Levels were determined throughout pregnancy, during term and preterm labour, and in the post-partum period. Serum tissue collagenase levels were elevated in pregnancy (P < 0.001). There was no difference between levels of serum collagenase prior to labour at term and those observed during labour. Similarly, there was no significant difference in levels obtained during preterm labour and those at a similar gestation in women who subsequently delivered at term. No significant decrease in levels had occurred by the 4th post-partum day. In view of these findings of unaltered matrix metalloproteinase-1 levels in association with labour, previous reports of raised serum collagenase activity in association with the onset of spontaneous labour, at term and preterm gestation periods, may be due to increased neutrophil collagenase activity.