Eosinophils in human cervical ripening

Emerging functions of tissue-resident eosinophils

Eosinophils are typically considered tissue-damaging effector cells in type 2 immune-related diseases. However, they are also increasingly recognized as important modulators of various homeostatic processes, suggesting they retain the ability to adapt their function to different tissue contexts. In this review, we discuss recent progress in our understanding of eosinophil activities within tissues, with particular emphasis on the gastrointestinal tract, where a large population of these cells resides under non-inflammatory conditions. We further examine evidence of their transcriptional and functional heterogeneity and highlight environmental signals emerging as key regulators of their activities, beyond classical type 2 cytokines.

Relationship between plasma concentrations of estradiol-17β and progesterone and the distribution of epithelial and inflammatory cells in the external opening of the river buffaloes’ uterine cervix during the gestational period

Changes in the distribution of the epithelial and inflammatory cells in the external opening of the uterine cervix in river buffaloes at three different occasions during the gestation period were investigated by light microscopic evaluation of mucus smears prepared by wet swab sampling and Giemsa-stained. Forty five pregnant river buffaloes that were in the first (n=15), second (n=15) and third (n=15) approximately equal parts of their gestation period were sampled twice concurrently by individual wet swabs from the external opening of the uterine cervix. Five smears were prepared from each sample. Immediately after mucus sampling, blood samples were obtained from the jugular vein of each animal, centrifuged immediately and stored at -20 oC to assay the plasma levels of estradiol-17β and progesterone. The results showed that changes in the percentage of the vacuolated and non-vacuolated epithelial cells, lymphocytes, eosinophils, and basophils were not statistically significant between the groups, which suggests that as the pregnancy progressed, changes in the blood levels of estradiol-17β and progesterone had little or no effect on the distribution of these cells in the region, but changes in the percentage of neutrophils were statistically significant between the groups. It was also found that changes in the percentage of macrophages between the second and third trimesters of the gestation period were not significant, but the difference between the first and the other trimesters was statistically significant. It was concluded that the percentages of neutrophils and macrophages increase significantly as the plasma concentrations of progesterone decrease during the gestation.

Assessing Phenotypic Heterogeneity in Intestinal Tissue Eosinophils

Eosinophils are primarily tissue-dwelling leukocytes. Utilization of flow cytometry techniques applied to digested tissues is expanding the scope of organs within which eosinophils are identified at baseline and is providing deeper insights into categorizing phenotypically and functionally distinct tissue-resident eosinophil subpopulations in health and disease. Here we describe a tissue digestion protocol and flow cytometry gating strategy for identification and isolation of tissue eosinophils from the small intestine of mice. This protocol is also amenable to the isolation and characterization of colonic eosinophils, and of intestinal eosinophils from human resected tissues.

Emerging roles of infiltrating granulocytes and monocytes in homeostasis

The infiltration of naïve tissues by myeloid cells has been long related to their clearance and the physiological cell turnover, however, increasing evidence shows that they can additionally fulfill specific, non-immune functions in different tissues. There is also growing evidence to support that infiltrated granulocytes and monocytes respond to different environments by modulating gene expression and cytokine production, which in turn contribute to the normal function of the host tissue. This review will address the roles of immigrated myeloid cells in different tissues and their crosstalk with the host tissue environments.

The emerging roles of eosinophils in mucosal homeostasis

Eosinophils are granulocytes, typically implicated as end-stage effector cells in type-II immune responses. They are capable of producing a wide array of pre-formed molecules which render them with vast potential to influence a wide variety of processes. Nonetheless, eosinophil research has traditionally focused on their role in anti-helminthic responses and pathophysiological processes in type-II immune disorders, such as allergy and asthma, where eosinophilia is a hallmark phenotype. However, a number of key studies over the past decade have placed this restricted view of eosinophil function into question, presenting additional evidence for eosinophils as critical regulators of various homeostatic processes including immune maintenance, organ development, and tissue regeneration.

Evolution of male pregnancy associated with remodeling of canonical vertebrate immunity in seahorses and pipefishes

Among vertebrates, pregnancy has evolved more than 150 times independently. A fundamental problem for pregnancy to evolve is inadvertent rejection of the embryo when being recognized as foreign tissue by the vertebrate’s adaptive immune system. We show that the unique evolution of male pregnancy in pipefishes and seahorses coincided with a genomic modification of one arm of the adaptive immune system. Our findings indicate a trade-off between immunological tolerance and embryo rejection to accompanying the emergence of male pregnancy. That syngnathids survive in an ocean of microbes despite their drastically modified immune defense suggests an unexpected immunological flexibility. Our results may improve the understanding of immune-deficiency diseases and call for a reassessment of vertebrate immunity.

A fundamental problem for the evolution of pregnancy, the most specialized form of parental investment among vertebrates, is the rejection of the nonself-embryo. Mammals achieve immunological tolerance by down-regulating both major histocompatibility complex pathways (MHC I and II). Although pregnancy has evolved multiple times independently among vertebrates, knowledge of associated immune system adjustments is restricted to mammals. All of them (except monotremata) display full internal pregnancy, making evolutionary reconstructions within the class mammalia meaningless. Here, we study the seahorse and pipefish family (syngnathids) that have evolved male pregnancy across a gradient from external oviparity to internal gestation. We assess how immunological tolerance is achieved by reconstruction of the immune gene repertoire in a comprehensive sample of 12 seahorse and pipefish genomes along the “male pregnancy” gradient together with expression patterns of key immune and pregnancy genes in reproductive tissues. We found that the evolution of pregnancy coincided with a modification of the adaptive immune system. Divergent genomic rearrangements of the MHC II pathway among fully pregnant species were identified in both genera of the syngnathids: The pipefishes (Syngnathus) displayed loss of several genes of the MHC II pathway while seahorses (Hippocampus) featured a highly divergent invariant chain (CD74). Our findings suggest that a trade-off between immunological tolerance and embryo rejection accompanied the evolution of unique male pregnancy. That pipefishes survive in an ocean of microbes without one arm of the adaptive immune defense suggests a high degree of immunological flexibility among vertebrates, which may advance our understanding of immune-deficiency diseases.

Immunobiology of Cervix Ripening

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

Spatio-temporal distribution of eosinophils in the mouse uterus during peri-implantation period

Embryo implantation is an immunologically paradoxical event. In humans and rodents, blastocysts adhere to uterine epithelium and then invade into endometrial stroma, while maternal body is protected from extraneous materials by its immune system. Eosinophils, a kind of leucocytes involving parasitic infections and allergic response, increase in number in uterus when serum estrogen level is elevated during estrus cycles. However, response of uterine eosinophils to ovarian estrogen during peri-implantation period is not clear. Therefore, we investigated the distribution of eosinophils in murine peri-implantation uterus. On day 0.5 of pregnancy, eosinophils were found primarily in endometrial stroma near the luminal epithelium, whereas they were primarily distributed in basal endometrium and myometrium on day 3.5 of pregnancy. The number of uterine eosinophils on day 4.5 of pregnancy was significantly increased by inhibition of maternal estrogen action. Collectively, our results indicate that the ovarian estrogen negatively regulates uterine eosinophil distribution during peri-implantation period and provide insight into a role of maternal immune system in embryo implantation.

Functions of tissue-resident eosinophils

Eosinophils are a prominent cell type in particular host responses such as the response to helminth infection and allergic disease. Their effector functions have been attributed to their capacity to release cationic proteins stored in cytoplasmic granules by degranulation. However, eosinophils are now being recognized for more varied functions in previously underappreciated diverse tissue sites, based on the ability of eosinophils to release cytokines (often preformed) that mediate a broad range of activities into the local environment. In this Review, we consider evolving insights into the tissue distribution of eosinophils and their functional immunobiology, which enable eosinophils to secrete in a selective manner cytokines and other mediators that have diverse, 'non-effector' functions in health and disease.

IL-4-secreting eosinophils promote endometrial stromal cell proliferation and prevent Chlamydia-induced upper genital tract damage

Genital Chlamydia trachomatis infections in women typically are asymptomatic and do not cause permanent upper genital tract (UGT) damage. Consistent with this presentation, type 2 innate and T_H2 adaptive immune responses associated with dampened inflammation and tissue repair are elicited in the UGT of Chlamydia-infected women. Primary C. trachomatis infection of mice also causes no genital pathology, but unlike women, does not generate Chlamydia-specific T_H2 immunity. Herein, we explored the significance of type 2 innate immunity for restricting UGT tissue damage in Chlamydia-infected mice, and in initial studies intravaginally infected wild-type, IL-10^-/-, IL-4^-/-, and IL-4Rα^-/- mice with low-dose C. trachomatis inoculums. Whereas Chlamydia was comparably cleared in all groups, IL-4^-/- and IL-4Rα^-/- mice displayed endometrial damage not seen in wild-type or IL-10^-/- mice. Congruent with the aberrant tissue repair in mice with deficient IL-4 signaling, we found that IL-4Rα and STAT6 signaling mediated IL-4-induced endometrial stromal cell (ESC) proliferation ex vivo, and that genital administration of an IL-4-expressing adenoviral vector greatly increased in vivo ESC proliferation. Studies with IL-4-IRES-eGFP (4get) reporter mice showed eosinophils were the main IL-4-producing endometrial leukocyte (constitutively and during Chlamydia infection), whereas studies with eosinophil-deficient mice identified this innate immune cell as essential for endometrial repair during Chlamydia infection. Together, our studies reveal IL-4-producing eosinophils stimulate ESC proliferation and prevent Chlamydia-induced endometrial damage. Based on these results, it seems possible that the robust type 2 immunity elicited by Chlamydia infection of human genital tissue may analogously promote repair processes that reduce phenotypic disease expression.

The Eosinophil in Health and Disease: from Bench to Bedside and Back

Historically, eosinophils have been considered as end-stage cells involved in host protection against parasitic infection and in the mechanisms of hypersensitivity. However, later studies have shown that this multifunctional cell is also capable of producing immunoregulatory cytokines and soluble mediators and is involved in tissue homeostasis and modulation of innate and adaptive immune responses. In this review, we summarize the biology of eosinophils, including the function and molecular mechanisms of their granule proteins, cell surface markers, mediators, and pathways, and present comprehensive reviews of research updates on the genetics and epigenetics of eosinophils. We describe recent advances in the development of epigenetics of eosinophil-related diseases, especially in asthma. Likewise, recent studies have provided us with a more complete appreciation of how eosinophils contribute to the pathogenesis of various diseases, including hypereosinophilic syndrome (HES). Over the past decades, the definition and criteria of HES have been evolving with the progress of our understanding of the disease and some aspects of this disease still remain controversial. We also review recent updates on the genetic and molecular mechanisms of HES, which have spurred dramatic developments in the clinical strategies of diagnosis and treatment for this heterogeneous group of diseases. The conclusion from this review is that the biology of eosinophils provides significant insights as to their roles in health and disease and, furthermore, demonstrates that a better understanding of eosinophil will accelerate the development of new therapeutic strategies for patients.

The expanding role(s) of eosinophils in health and disease

Surprisingly, the role(s) of eosinophils in health and disease is often summarized by clinicians and basic research scientists as a pervasive consensus opinion first learned in medical/graduate school. Eosinophils are rare white blood cells whose activities are primarily destructive and are only relevant in parasitic infections and asthma. However, is this consensus correct? This review argues that the wealth of available studies investigating the role(s) of eosinophils in both health and disease demonstrates that the activities of these granulocytes are far more expansive and complex than previously appreciated. In turn, this greater understanding has led to the realization that eosinophils have significant contributory roles in a wide range of diseases. Furthermore, published studies even implicate eosinophil-mediated activities in otherwise healthy persons. We suggest that the collective reports in the literature showing a role for eosinophils in an ever-increasing number of novel settings highlight the true complexity and importance of this granulocyte. Indeed, discussions of eosinophils are no longer simple and more often than not now begin with the question/statement "Did you know …?"

Cervical remodeling during pregnancy and parturition

Appropriate and timely cervical remodeling is key for successful birth. Premature cervical opening can result in preterm birth which occurs in 12.5% of pregnancies. Research focused on the mechanisms of term and preterm cervical remodeling is essential to prevent prematurity. This review highlights recent findings that better define molecular processes driving progressive disorganization of the cervical extracellular matrix. This includes studies that redefine the role of immune cells and identify diverse functions of the cervical epithelia and hyaluronan in remodeling. New investigations proposing that infection-induced premature cervical remodeling is distinct from the normal process are presented. Recent advances in our understanding of term and preterm cervical remodeling provide new directions for investigation and compel investigators to reevaluate currently accepted models.

Temporal changes in myeloid cells in the cervix during pregnancy and parturition

Preterm birth occurs at a rate of 12.7% in the U.S. and is the primary cause of fetal morbidity in the first year of life as well as the cause of later health problems. Elucidation of mechanisms controlling cervical remodeling is critical for development of therapies to reduce the incidence of prematurity. The cervical extracellular matrix must be disorganized during labor to allow birth, followed by a rapid repair postpartum. Leukocytes infiltrate the cervix before and after birth and are proposed to regulate matrix remodeling during cervical ripening via release of proteolytic enzymes. In the current study, flow cytometry and cell sorting were used to determine the role of immune cells in cervical matrix remodeling before, during, and after parturition. Markers of myeloid cell differentiation and activation were assessed to define phenotype and function. Tissue monocytes and eosinophils increased in the cervix before birth in a progesterone-regulated fashion, whereas macrophage numbers were unchanged. Neutrophils increased in the postpartum period. Increased mRNA expression of Csfr1 and markers of alternatively activated M2 macrophages during labor or shortly postpartum suggest a function of M2 macrophages in postpartum tissue repair. Changes in cervical myeloid cell numbers are not reflected in the peripheral blood. These data along with our previous studies suggest that myeloid-derived cells do not orchestrate processes required for initiation of cervical ripening before birth. Additionally, macrophages with diverse phenotypes (M1 and M2) are present in the cervix and are most likely involved in the postpartum repair of tissue.

Relaxation of the mouse pubic symphysis during late pregnancy is not accompanied by the influx of granulocytes

In some animals, such as mice and guinea pigs, a hormonally controlled mechanism increases the flexibility of the pubic symphysis and enhances the cervical remodeling necessary for safe delivery. Cervical ripening during pregnancy is associated with a paradoxical influx of leukocytes. However, the changes in cell metabolism during relaxation of the mouse pubic symphysis for delivery have not been extensively studied. In this work, we used light microscopy and transmission and scanning electron microcopy, as well as immunohistochemistry and Western blotting for MMP-8, to investigate the involvement of granulocytes or resident stromal cells in the relaxation of the virgin pubic symphysis during late pregnancy (days 18 and 19, before delivery) in vivo and in explanted joints. MMP-8 was studied because this collagenase is a hallmark for cervical ripening associated with the influx of granulocytes during late pregnancy. Extensive dissolution and disorganization of the extracellular matrix was seen around fibroblastic-like cells in late pregnancy. In contrast to the cervix (positive control), morphological and immunohistochemical analyses revealed that there was no characteristic cellular inflammatory response in the interpubic tissue. Staining for MMP-8 was observed in chondroid and fibroblastic-like cells of virgin and relaxed interpubic ligament, respectively. However, no granulocytes were seen during the extensive remodeling of the pubic joint in late pregnancy. These results indicate that constitutive stromal cells may have an important role in tissue relaxation during remodeling of the pubic symphysis in pregnancy.

Cervical leukocyte sub-populations in idiopathic preterm labour

OBJECTIVE

To investigate cervical epithelial leukocyte sub-populations in pregnant women with a history of idiopathic preterm labour.

METHODS

A prospective observational study was undertaken of 106 women with a past history of idiopathic preterm delivery following spontaneous labour. A cytobrush was used to sample the epithelium of the cervix at 12-16 weeks of gestation and again 8 weeks later. All women had investigations for cervical and vaginal infection as well as serial transvaginal ultrasonography of their cervix; the mode and gestation at delivery were recorded. Leukocyte sub-populations were examined using immunocytochemistry, and the number of leukocytes per total cell count was calculated.

MAIN OUTCOME MEASURES

Cervical epithelial leukocytes populations were (1) described in pregnancy, (2) observed over increasing gestation, (3) analysed in women who developed marked cervical shortening and (4) in those whose preterm labour recurred.

RESULTS

There was no significant change in cervical epithelial leukocyte populations during the second trimester of pregnancy. There was no association between cervical leukocytes and cervical shortening. Women with idiopathic preterm labour that recurred had fewer cervical macrophages at the beginning of the second trimester of pregnancy than those whose subsequent pregnancy progressed beyond 35 weeks of gestation.

CONCLUSIONS

Cervical epithelial macrophages may serve to prevent recurrent preterm labour, possibly by preventing ascending infection.

Timing of Neutrophil Activation and Expression of Proinflammatory Markers Do Not Support a Role for Neutrophils in Cervical Ripening in the Mouse1

The mechanisms that facilitate remodeling of the cervix in preparation for and during parturition remain poorly understood. In the current study, we have evaluated the timing of inflammatory cell migration in cervix through comparisons between wild-type mice and steroid 5alpha-reductase type 1 null mice (Srd5a1-/-), which fail to undergo cervical ripening due to insufficient local progesterone metabolism. The timing of migration and distribution of macrophages, monocytes, and neutrophils were examined using cervices from wild-type and Srd5a1-/- mice before Day 15 (d15) and during cervical ripening (late d18), and postpartum (d19). Neutrophil numbers were quantitated by cell counts and activity was estimated by measurement of myeloperoxidase activity. The mRNA and/or protein expression of neutrophil chemoattractants, CXCL2 and CXCL1, and other proinflammatory and adhesion molecules, including IL1A, IL1B, TNF, CCL11, CCL5, CCL3, ITGAM, and ICAM1, were measured in cervices collected before, during, and after birth. The effect of neutrophil depletion on parturition was tested. Tissue macrophages, myeloperoxidase activity, and expression of proinflammatory molecules are not increased within the cervix until after birth. Neutrophil numbers do not change after birth and neutrophil depletion before term has no effect on timing or success of parturition. These results suggest that cervical ripening does not require neutrophils. Moreover, neutrophil activation and a general inflammatory response are not initiated within the cervix until shortly after parturition. The timing of inflammatory cell migration and activation in pregnant cervix suggest a role for these cells in postpartum remodeling of the cervix rather than in the initiation of cervical ripening at parturition.

Vaginal and Cervical Dilatation Intrapartum is Associated with Eosinophilic Infiltration in the Cow but not in the Sheep

During parturition maximal dilatation of the vagina and cervix is necessary for expulsion of the neonate. The aim of the present study was to characterize the cell infiltration of the vagina and cervix that is associated with this event in cows and sheep. For this purpose, vaginal and cervical tissue were removed from four pluriparous cows and four sheep immediately after delivery of the neonate by biopsy under visual control (group 1), and the eosinophilic granulocytes were stained selectively. Four cows that were in interoestrus were used for control (group 2). In a third group of cows (n=10), blood samples were taken to determine the concentration of eosinophilic granulocytes from the fifth day antepartum up to the sixth day postpartum (group 3). A high degree of infiltration with eosinophilic granulocytes was detected in the bovine vagina and cervix intrapartum but not during interoestrus and in the ovine tissue intrapartum (p <0.001). In the bovine tissue, the cell density was higher in the vagina than in the cervix (p <0.05). The intrapartal tissue infiltration was associated with a short-term blood eosinopenia. In conclusion, this investigation demonstrates eosinophilic infiltration in the bovine vagina and cervix intrapartum, which differs from the situation in sheep. We suggest that this difference can be explained by the fact that cows deliver at high oestrogen and low progesterone values, but sheep show relatively high intrapartal P4 levels, which might suppress tissue infiltration with eosinophilic granulocytes.

Tissue Eosinophilia in Pemphigoid Gestationis: Association with Eotaxin and Upregulated Activation Markers on Transmigrated Eosinophils

PROBLEM

We studied chemotactic cytokines and activation of skin-homed eosinophils in pemphigoid gestationis, a rare autoimmune bullous disease of late pregnancy.

METHOD OF STUDY

Eotaxin and interleukin (IL)-5 were analysed in patients' blister fluid and serum by enzyme-linked immunosorbent assay. Lesional tissue was investigated for eotaxin deposition by immunohistochemistry. Adhesion molecules and activation markers on tissue eosinophils were analysed by immunofluorescence staining.

RESULTS

Eotaxin was elevated in serum of two pemphigoid gestationis patients compared with nine healthy pregnant women. Blister fluid contained even higher amounts of eotaxin and in addition IL-5. Eotaxin was mainly expressed in subepidermal tissue in close proximity to eosinophils that expressed high levels of adhesion molecules (CD11b, CD11c, CD18 and CD49d) and the activation marker HLA-DR.

CONCLUSIONS

High local levels of eotaxin and IL-5 as present in the blister fluid correspond to the high state of activation of the infiltrated eosinophils.

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.

Cytokines of the placenta and extra-placental membranes: roles and regulation during human pregnancy and parturition

Summary In an earlier, companion, review, we concluded that cytokines produced by the placenta and associated membranes are likely to be involved in control of the processes of implantation and placental development (Bowen et al., 2002). In this review, we discuss evidence that cytokines continue to be part of a paracrine/autocrine regulatory network in the placenta and membranes throughout the mid and late stages of gestation. Cytokines are involved in regulation of placental growth during these later stages of pregnancy and also function to protect the fetus from pathological organisms. The evidence, while not entirely consistent, suggests that production of certain cytokines within the extraplacental membranes is altered during normal term parturition, whereas in the villous placenta evidence of labour-associated changes is much more equivocal. Roles for cytokines have been postulated in many facets of parturition, including expulsion of the fetus by uterine contractions, membrane rupture, and dilation of the cervix. Imbalances and disruptions to the cytokine milieu have been implicated in a number of diseases of pregnancy involving abnormalities of both placental growth/establishment and initiation of parturition. Cytokine secretion induced by intrauterine infection is associated with increased occurrence or severity of some neonatal diseases. This wealth of data supports the view that cytokines are an integral part of a functional regulatory/communication network operating within the placental-maternal unit during normal gestation.

Sensory nerves and neuropeptides in uterine cervical ripening

At the time of parturition (fetal delivery) the uterine cervix must "ripen," becoming soft, pliable, and dilated to accommodate the fetus' delivery. The fundamental processes underlying cervical ripening remain poorly understood. Knowledge that abundant autonomic and sensory nerves supply the uterine cervix, that transection of afferent nerves supplying the cervix blocks parturition, and that some of the changes in the cervix resemble those seen in inflammatory reactions suggests nerves may have a role in the cervical ripening changes. The present study utilized immunohistochemistry, plasma extravasation, and solution hybridization-nuclease protection assay to elucidate the complement of primary afferent nerves and some receptors in the rat cervix during pregnancy, and to determine if they may have roles in the ripening process at term. This study revealed an abundance of nerves associated with the cervical vasculature and myometrial smooth muscle containing immunoreactivity for substance P, calcitonin gene-related peptide, secretoneurin, and nitric oxide synthase throughout pregnancy. Many of these are small unmyelinated capsaicin-sensitive C-fibers. Substance P- (NK1-) and calcitonin gene-related peptide receptors were apparent on uterine cervix vasculature from pregnant, parturient, and postpartum rats. NK1 receptor mRNA was maximal at 20 days of pregnancy. Plasma extravasation of i.v. administered Evans Blue or Monastral Blue was most pronounced at parturition (shortly after NK1 mRNA is maximal); this was similar to plasma extravasation evoked by i.v. administration of substance P or capsaicin-treatment. This study revealed new data about the nervous system of the rat uterine cervix and that these nerves and their transmitters could very well be part of a neurogenic inflammatory process involved in cervical ripening.

Effects of platelet-activating factor on cytokine production by human uterine cervical fibroblasts

Platelet-activating factor (PAF), a lipid that acts as a potent proinflammatory mediator, is involved in several reproductive processes including parturition. To investigate the effects of PAF on expression of various cytokines by cultured human uterine cervical fibroblasts obtained at term prior to labour, Northern blot analyses and enzyme-linked immunosorbent assays were performed. C-PAF, a stable analogue of PAF, increased expression of interleukin-6 and -8 mRNA in a dose-dependent manner (10(-10) to 10(-8) mol/l of C-PAF), and the expression peaked within 4 h. The corresponding protein concentrations were increased in culture media. Monocyte chemoattractant protein-1 mRNA showed marked induction by 10(-8) mol/l of C-PAF; this peaked by 4 h and was followed by an increase in the protein concentration. Another cytokine, RANTES (regulated upon activation, normal T cell expressed and secreted) showed marked mRNA induction by 10(-8) mol/l of C-PAF, and continued to increase in a time-dependent manner until 24 h. The protein concentration was correspondingly increased in the medium. The PAF-induced cytokine production was abolished by co-incubation with WEB 2170, a specific PAF receptor antagonist. PAF may stimulate local production of cytokines which may induce migration of leukocytes and accelerate collagenolysis in the uterine cervix, thus contributing to cervical ripening during parturition.

Eosinophil cationic protein and eosinophil protein X: human amniotic fluid concentrations and gestational tissue content at term

The aim of this study was to determine the presence and concentration of immunoreactive eosinophil cationic protein (ECP) and eosinophil protein X (EPX) in human amniotic fluid at term and assess labour-associated changes in their mean concentrations. In addition, ECP and EPX content in term amnion, choriodecidua and placenta obtained before and after labour and delivery was established. Immunoreactive ECP and EPX were identified in all samples of amniotic fluid (n=47) and gestational tissue (n=60) assayed. EPX was quantitatively more abundant than ECP in both amniotic fluid and gestational tissues. In amniotic fluid, ECP and EPX concentrations increased 8-fold (P<0.02) and 1.5-fold (P<0.02), respectively, with labour onset. In gestational tissues, a labour-associated change in tissue content was only identified for ECP in choriodecidua, which increased 1.9-fold with labour and delivery (P<0.01). The labour-associated increase in amniotic fluid concentrations of ECP and EPX demonstrated in this study is consistent with the well-characterized role of these proteins in inflammatory reactions. It remains to be established whether the observed increase in ECP and EPX amniotic fluid concentrations is an epiphenomenon of labour onset or is involved causally in this process.