The importance of fibroblasts in remodelling of the human uterine cervix during pregnancy and parturition

Immunocompetent PDMS-Free Organ-on-Chip Model of Cervical Cancer Integrating Patient-Specific Cervical Fibroblasts and Neutrophils

Despite preventive measures and available treatments, cervical cancer still ranks as the fourth most prevalent cancer among women worldwide and remains the leading cause of cancer death in women in many developing countries. To gain further insights into pathogenesis and to develop novel (immuno)therapies, more sophisticated human models recreating patient heterogeneities and including aspects of the tumor microenvironment are urgently required. A novel polydimethylsiloxane-free microfluidic platform, designed specifically for the generation and ccultivation of cervical cancerous tissue, is introduced. The microscale open-top tissue chambers of the cervical cancer-on-chip (CCoC) enable facile generation and long-term cultivation of SiHa spheroids in co-culture with donor-derived cervical fibroblasts. The resulting 3D tissue emulates physiological architecture and allows dissection of distinct effects of the stromal tissue on cancer viability and growth. Treatment with cisplatin at clinically-relevant routes of administration and dosing highlights the platform's applicability for drug testing. Moreover, the model is amenable for integration and recruitment of donor-derived neutrophils from the microvasculature-like channel into the tissue, all while retaining their ability to produce neutrophil extracellular traps. In the future, the immunocompetent CCoC featuring donor-specific primary cells and tumor spheroids has the potential to contribute to the development of new (immuno)therapeutic options.

The Role of Genetics in Preterm Birth

Preterm birth (PTB), defined as the birth of a child before 37 completed weeks gestation, affects approximately 11% of live births and is the leading cause of death in children under 5 years. PTB is a complex disease with multiple risk factors including genetic variation. Much research has aimed to establish the biological mechanisms underlying PTB often through identification of genetic markers for PTB risk. The objective of this review is to present a comprehensive and updated summary of the published data relating to the field of PTB genetics. A literature search in PubMed was conducted and English studies related to PTB genetics were included. Genetic studies have identified genes within inflammatory, immunological, tissue remodeling, endocrine, metabolic, and vascular pathways that may be involved in PTB. However, a substantial proportion of published data have been largely inconclusive and multiple studies had limited power to detect associations. On the contrary, a few large hypothesis-free approaches have identified and replicated multiple novel variants associated with PTB in different cohorts. Overall, attempts to predict PTB using single "-omics" datasets including genomic, transcriptomic, and epigenomic biomarkers have been mostly unsuccessful and have failed to translate to the clinical setting. Integration of data from multiple "-omics" datasets has yielded the most promising results.

Parity and gestational age are associated with vaginal microbiota composition in term and late term pregnancies

Background

Vaginal microbiota and its potential contribution to preterm birth is under intense research. However, only few studies have investigated the vaginal microbiota in later stages of pregnancy or at the onset of labour.

Methods

We used 16S rRNA gene amplicon sequencing to analyse cross-sectional vaginal swab samples from 324 Finnish women between 37–42 weeks of gestation, sampled before elective caesarean section, at the onset of spontaneous labour, and in pregnancies lasting ≥41 weeks of gestation. Microbiota data were combined with comprehensive clinical data to identify factors associated with microbiota variation.

Findings

Vaginal microbiota composition associated strongly with advancing gestational age and parity, i.e. presence of previous deliveries. Absence of previous deliveries was a strong predictor of Lactobacillus crispatus dominated vaginal microbiota, and the relative abundance of L. crispatus was higher in late term pregnancies, especially among nulliparous women.

Interpretation

This study identified late term pregnancy and reproductive history as factors underlying high abundance of gynaecological health-associated L. crispatus in pregnant women. Our results suggest that the vaginal microbiota affects or reflects the regulation of the duration of gestation and labour onset, with potentially vast clinical utilities. Further studies are needed to address the causality and the mechanisms on how previous labour, but not pregnancy, affects the vaginal microbiota. Parity and gestational age should be accounted for in future studies on vaginal microbiota and reproductive outcomes.

Funding

This research was supported by EU H2020 programme Sweet Crosstalk ITN (814102), Academy of Finland, State Research Funding, and University of Helsinki.

Progesterone Receptor Signaling Selectively Modulates Cytokine-Induced Global Gene Expression in Human Cervical Stromal Cells

Preterm birth (PTB) is the leading cause of morbidity and mortality in infants <1 year of age. Intrauterine inflammation is a hallmark of preterm and term parturition; however, this alone cannot fully explain the pathobiology of PTB. For example, the cervix undergoes a prolonged series of biochemical and biomechanical events, including extracellular matrix (ECM) remodeling and mechanochemical changes, culminating in ripening. Vaginal progesterone (P₄) prophylaxis demonstrates great promise in preventing PTB in women with a short cervix (<25 mm). We used a primary culture model of human cervical stromal fibroblasts to investigate gene expression signatures in cells treated with interleukin-1β (IL-1β) in the presence or absence of P₄ following 17β-estradiol (17β-E₂) priming for 7–10 days. Microarrays were used to measure global gene expression in cells treated with cytokine or P₄ alone or in combination, followed by validation of select transcripts by semiquantitative polymerase chain reactions (qRT-PCR). Primary/precursor (MIR) and mature microRNAs (miR) were quantified by microarray and NanoString^® platforms, respectively, and validated by qRT-PCR. Differential gene expression was computed after data normalization followed by pathway analysis using Kyoto Encyclopedia Genes and Genomes (KEGG), Panther, Gene Ontology (GO), and Ingenuity Pathway Analysis (IPA) upstream regulator algorithm tools. Treatment of fibroblasts with IL-1β alone resulted in the differential expression of 1432 transcripts (protein coding and non-coding), while P₄ alone led to the expression of only 43 transcripts compared to untreated controls. Cytokines, chemokines, and their cognate receptors and prostaglandin endoperoxide synthase-2 (PTGS-2) were among the most highly upregulated transcripts following either IL-1β or IL-1β + P₄. Other prominent differentially expressed transcripts were those encoding ECM proteins, ECM-degrading enzymes, and enzymes involved in glycosaminoglycan (GAG) biosynthesis. We also detected differential expression of bradykinin receptor-1 and -2 transcripts, suggesting (prominent in tissue injury/remodeling) a role for the kallikrein–kinin system in cervical responses to cytokine and/or P₄ challenge. Collectively, this global gene expression study provides a rich database to interrogate stromal fibroblasts in the setting of a proinflammatory and endocrine milieu that is relevant to cervical remodeling/ripening during preparation for parturition.

Potential role of transforming growth factor-beta 1/Smad signaling in secondary lymphedema after cancer surgery

Secondary lymphedema often develops after cancer surgery, and over 250 million patients suffer from this complication. A major symptom of secondary lymphedema is swelling with fibrosis, which lowers the patient's quality of life, even if cancer does not recur. Nonetheless, the pathophysiology of secondary lymphedema remains unclear, with therapeutic approaches limited to physical or surgical therapy. There is no effective pharmacological therapy for secondary lymphedema. Notably, the lack of animal models that accurately mimic human secondary lymphedema has hindered pathophysiological investigations of the disease. Here, we developed a novel rat hindlimb model of secondary lymphedema and showed that our rat model mimics human secondary lymphedema from early to late stages in terms of cell proliferation, lymphatic fluid accumulation, and skin fibrosis. Using our animal model, we investigated the disease progression and found that transforming growth factor‐beta 1 (TGFB1) was produced by macrophages in the acute phase and by fibroblasts in the chronic phase of the disease. TGFB1 promoted the transition of fibroblasts into myofibroblasts and accelerated collagen synthesis, resulting in fibrosis, which further indicates that myofibroblasts and TGFB1/Smad signaling play key roles in fibrotic diseases. Furthermore, the presence of myofibroblasts in skin samples from lymphedema patients after cancer surgery emphasizes the role of these cells in promoting fibrosis. Suppression of myofibroblast‐dependent TGFB1 production may therefore represent an effective pharmacological treatment for inhibiting skin fibrosis in human secondary lymphedema after cancer surgery.

Inflammatory and anti-inflammatory markers in plasma: from late pregnancy to early postpartum

During pregnancy, the woman's body undergoes tremendous changes in immune system adaptation. The immunological shifts that occur in pregnancy can partially be explained by alterations in hormonal levels. Furthermore, during pregnancy, many autoimmune diseases go into remission, only to flare again in the early postpartum period. Given these important changes in the clinical course of a number of autoimmune disorders, surprisingly little has been done to investigate the inflammatory profile changes across pregnancy and the postpartum period. Thus, the aim of this study was to describe how inflammatory and anti-inflammatory markers change from late pregnancy to the early postpartum period, using a multiplexed assay consisting of both well-known as well as exploratory proteins. Two-hundred-and-ninety women were included in this study and donated a total of 312 blood samples; 198 in late pregnancy (~gw38) and 114 in the postpartum period (~w8). The plasma blood samples were analyzed for 92 immune system related protein markers using Proseek Multiplex Inflammation I panel, a high-sensitivity assay based on proximity extension assay technology. Fifty-six inflammatory and anti-inflammatory markers were significantly different between pregnancy and the postpartum, of which 50 survived corrections for multiple comparisons. Out of these 50 markers, 41 decreased from pregnancy to postpartum, while the remaining 9 increased in the postpartum period. The top five markers with the greatest decrease in the postpartum period were Leukemia inhibitory factor receptor (LIF-R), Latency-associated peptide Transforming growth factor beta-1 (LAP TGF-beta-1), C-C motif chemokine 28 (CCL28), Oncostatin M (OSM) and Fibroblast growth factor 21 (FGF21). Top three markers that increased in the postpartum period were Tumor necrosis factor ligand superfamily member 11 (TRANCE), Tumor necrosis factor ligand superfamily member 12 (TWEAK), and C-C motif chemokine/Eotaxin (CCL11). This study revealed that the majority of the markers decreased from pregnancy to postpartum, and only a few increased. Several of the top proteins that were higher in pregnancy than postpartum have anti-inflammatory and immune modulatory properties promoting pregnancy progress. These results clearly reflect the tremendous change in the immune system in the pregnancy to postpartum transition.

Estradiol-regulated innate antiviral responses of human endometrial stromal fibroblasts

PROBLEM

The contribution of fibroblasts to innate immune protection of the human female reproductive tract (FRT) against viral pathogens is relatively unknown.

METHOD OF STUDY

Endometrial (EM), endocervical (Cx) and ectocervical (ECx) fibroblasts were isolated from hysterectomy patients and grown in vitro. Fibroblasts were treated with the viral mimic poly (I:C) in the presence or absence of the sex hormone estradiol (E2 ), with gene expression measured by real-time RT-PCR and protein secretion by ELISA.

RESULTS

Poly (I:C) induced the expression of the interferon-stimulated genes (ISG) MxA, OAS2 and APOBEC3G, and the cytokines MCP-1, IL-8, IL-6, CCL20, IFNβ and RANTES by fibroblasts from all three sites. ISG upregulation was dependent upon Type I IFN signaling. E2 inhibited the poly (I:C)-induced upregulation of MxA and OAS2 in EM fibroblasts, but not Cx or ECx fibroblasts. E2 upregulated SDF-1α by EM fibroblasts but had no effect on secretion of other cytokines either alone or in the presence of poly (I:C). Conditioned media (CM) from poly (I:C)-treated or E2 -treated fibroblasts significantly reduced HIV infection of CD4+ T cells.

CONCLUSION

Stromal fibroblasts represent a level of innate immune protection against viral pathogens in the FRT beyond that seen with epithelial cells and immune cells. Our findings indicate that fibroblasts FRT are selectively responsive to E2 , capable of initiating an antiviral response against viral pathogens and may play a role in preventing HIV infection of CD4+ T cells.

Inflammatory markers in women with postpartum depressive symptoms

Postpartum depression (PPD) is a devastating disorder affecting not only more than 10% of all women giving birth, but also the baby, the family, and the society. Compiling evidence suggests the involvement of the immune system in the pathophysiology of major depression; yet, the immune response in perinatal depression is not as well studied. The aim of this study was to investigate the alterations in peripheral levels of inflammatory biomarkers in 169 Swedish women with and without depressive symptoms according to the Edinburgh postnatal depression scale or the M.I.N.I neuropsychiatric interview at eight weeks postpartum. Among the 70 markers analyzed with multiplex proximity extension assay, five were significantly elevated in women with postpartum depressive symptoms in the adjusted LASSO logistic regression analysis: Tumor necrosis factor ligand superfamily member (TRANCE) (OR-per 1 SD increase = 1.20), Hepatocyte growth factor (HGF) (OR = 1.17) Interleukin (IL)-18 (OR = 1.06), Fibroblast growth factor 23 (FGF-23) (OR = 1.25), and C-X-C motif chemokine 1 (CXCL1) (OR 1.11). These results indicate that women with PPD have elevated levels of some inflammatory biomarkers. It is, therefore, plausible that PPD is associated with a compromised adaptability of the immune system.

Functional genomics of stromal cells in chronic inflammatory diseases

PURPOSE OF REVIEW

Stroma is a broad term referring to the connective tissue matrix in which other cells reside. It is composed of diverse cell types with functions such as extracellular matrix maintenance, blood and lymph vessel development, and effector cell recruitment. The tissue microenvironment is determined by the molecular characteristics and relative abundances of different stromal cells such as fibroblasts, endothelial cells, pericytes, and mesenchymal precursor cells. Stromal cell heterogeneity is explained by embryonic developmental lineage, stages of differentiation to other cell types, and activation states. Interaction between immune and stromal cell types is critical to wound healing, cancer, and a wide range of inflammatory diseases. Here, we review recent studies of inflammatory diseases that use functional genomics and single-cell technologies to identify and characterize stromal cell types associated with pathogenesis.

RECENT FINDINGS

High dimensional strategies using mRNA sequencing, mass cytometry, and fluorescence activated cell-sorting with fresh primary tissue samples are producing detailed views of what is happening in diseased tissue in rheumatoid arthritis, inflammatory bowel disease, and cancer. Fibroblasts positive for CD90 (Thy-1) are enriched in the synovium of rheumatoid arthritis patients. Single-cell RNA-seq studies will lead to more discoveries about the stroma in the near future.

SUMMARY

Stromal cells form the microenvironment of inflamed and diseased tissues. Functional genomics is producing an increasingly detailed view of subsets of stromal cells with pathogenic functions in rheumatic diseases and cancer. Future genomics studies will discover disease mechanisms by perturbing molecular pathways with chemokines and therapies known to affect patient outcomes. Functional genomics studies with large sample sizes of patient tissues will identify patient subsets with different disease phenotypes or treatment responses.

Interaction Between Progesterone and Interleukin-1β in Modulating Progesterone Receptor Expression and the Inflammatory Phenotype in Human Cervical Fibroblasts

Progesterone helps maintain cervical structure during pregnancy via the progesterone receptor (PR). Two PR isoforms exist, PR-A and PR-B, which have overlapping as well as isoform-specific target genes. During late gestation, leukocytes infiltrate the cervical stroma accompanied by increased cervical cytokine levels, resembling an inflammatory process. We examined interleukin (IL)-1β regulation of the expression of PR-A, PR-B, and genes governing prostaglandin synthesis in human cervical fibroblasts (HCFs). Since progesterone has been shown to exert anti-inflammatory actions, we also examined the capacity of progesterone (R5020) to ameliorate the actions of IL-1β in HCFs. Interleukin-1β induced both PR-A and PR-B mRNA in HCFs. Interleukin-1β induced a rapid and transient loss of both PR-A and PR-B protein, followed by a latent (24 hours) increase in both PR isoforms. R5020 negated the IL-1β-induced increase in PR-A and PR-B mRNA and protein as well as the rapid IL-1β-induced downregulation of nuclear PR. Interleukin-1β induced prostaglandin G/H synthase-2 (PGHS-2), but not prostaglandin G/H synthase-1 (PGHS-1), as well as prostaglandin E synthase-1 (PGES-1), but not prostaglandin F synthase (PGFS). R5020 did not ameliorate IL-1β induction of PGHS-2 or PGES-1. Blockade of prostaglandin synthesis (indomethacin) prevented both the IL-1β-induced increase in PR mRNA and the acute decrease in PR-A and PR-B protein, implicating a role for prostaglandins in regulating PR expression in HCFs. Although progesterone may function to maintain PR expression in a milieu of increasing cytokines in the late gestation human cervix, it does not exert an anti-inflammatory role with regard to prostaglandin E₂ (PGE2) production.

Lower inflammatory markers in women with antenatal depression brings the M1/M2 balance into focus from a new direction

BACKGROUND

Antenatal depression and use of serotonin reuptake inhibitors (SSRI) in pregnancy have both been associated with an increased risk of poor pregnancy outcomes, such as preterm birth and impaired fetal growth. While the underlying biological pathways for these complications are poorly understood, it has been hypothesized that inflammation may be a common physiological pathway. The aim of the present study was to assess peripheral inflammatory markers in healthy women, women with antenatal depression, and in women using SSRI during pregnancy.

METHODS

160 healthy pregnant controls, 59 women with antenatal depression and 39 women on treatment with SSRIs were included. The relative levels of 92 inflammatory proteins were analyzed by proximity extension assay technology.

RESULTS

Overall, 23 of the inflammatory markers were significantly lower in women with antenatal depression and in women on treatment with SSRIs in comparison with the healthy controls. No difference in any of the inflammatory markers was observed between women with antenatal depression and those who were using SSRI. Top three inflammatory markers that were down-regulated in women with antenatal depression were TNF-related apoptosis-inducing ligand (TRAIL), p=0.000001, macrophage colony-stimulating factor 1 (CSF-1), p=0.000004, and fractalkine (CX3CL1), p=0.000005. Corresponding inflammatory markers in SSRI users were CSF-1, p=0.000011, vascular endothelial growth factor A (VEGF-A), p=0.000016, and IL-15 receptor subunit alpha (IL-15RA), p=0.000027. The inflammatory markers were negatively correlated with cortisone serum concentrations in controls, but not in the cases. Differential DNA methylation of was found for seven of these inflammatory markers in an independent epigenetics cohort.

CONCLUSION

Women with antenatal depression or on SSRI treatment have lower levels of a number of peripheral inflammatory markers than healthy pregnant controls. Hypothetically, this could be due to dysregulated switch to the pro-M2 milieu that characterizes normal third trimester pregnancy. However, longitudinal blood sampling is needed to elucidate whether the presumably dysregulated M2 shift is driving the development of antenatal depression or is a result of the depression.

Inflammatory markers in late pregnancy in association with postpartum depression-A nested case-control study

Recent studies indicate that the immune system adaptation during pregnancy could play a significant role in the pathophysiology of perinatal depression. The aim of this study was to investigate if inflammation markers in a late pregnancy plasma sample can predict the presence of depressive symptoms at eight weeks postpartum. Blood samples from 291 pregnant women (median and IQR for days to delivery, 13 and 7-23days respectively) comprising 63 individuals with postpartum depressive symptoms, as assessed by the Edinburgh postnatal depression scale (EPDS≥12) and/or the Mini International Neuropsychiatric Interview (M.I.N.I.) and 228 controls were analyzed with an inflammation protein panel using multiplex proximity extension assay technology, comprising of 92 inflammation-associated markers. A summary inflammation variable was also calculated. Logistic regression, LASSO and Elastic net analyses were implemented. Forty markers were lower in late pregnancy among women with depressive symptoms postpartum. The difference remained statistically significant for STAM-BP (or otherwise AMSH), AXIN-1, ADA, ST1A1 and IL-10, after Bonferroni correction. The summary inflammation variable was ranked as the second best variable, following personal history of depression, in predicting depressive symptoms postpartum. The protein-level findings for STAM-BP and ST1A1 were validated in relation to methylation status of loci in the respective genes in a different population, using openly available data. This explorative approach revealed differences in late pregnancy levels of inflammation markers between women presenting with depressive symptoms postpartum and controls, previously not described in the literature. Despite the fact that the results do not support the use of a single inflammation marker in late pregnancy for assessing risk of postpartum depression, the use of STAM-BP or the novel notion of a summary inflammation variable developed in this work might be used in combination with other biological markers in the future.

Dermal fibroblasts induce cell cycle arrest and block epithelial-mesenchymal transition to inhibit the early stage melanoma development

Stromal fibroblasts are an integral part of the tumor stroma and constantly interact with cancer cells to promote their initiation and progression. However, the role and function of dermal fibroblasts during the early stage of melanoma development remain poorly understood. We, therefore, designed a novel genetic approach to deactivate stromal fibroblasts at the onset of melanoma formation by targeted ablation of β-catenin. To our surprise, melanoma tumors formed from β-catenin-deficient group (B16F10 mixed with β-catenin-deficient fibroblasts) appeared earlier than tumors formed from control group (B16F10 mixed with normal dermal fibroblasts). At the end point when tumors were collected, mutant tumors were bigger and heavier than control tumors. Further analysis showed that there were fewer amounts of stromal fibroblasts and myofibroblasts inside mutant tumor stroma. Melanoma tumors from control group showed reduced proliferation, down-regulated expression of cyclin D1 and increased expression of cyclin-dependent kinase inhibitor p16, suggesting dermal fibroblasts blocked the onset of melanoma tumor formation by inducing a cell cycle arrest in B16F10 melanoma cells. Furthermore, we discovered that dermal fibroblasts prevented epithelial-mesenchymal transition in melanoma cells. Overall, our findings demonstrated that dermal fibroblasts crosstalk with melanoma cells to regulate in vivo tumor development via multiple mechanisms, and the outcomes of their reciprocal interactions depend on activation states of stromal fibroblasts and stages of melanoma development.

Maternal age effects on myometrial expression of contractile proteins, uterine gene expression, and contractile activity during labor in the rat

Advanced maternal age of first time pregnant mothers is associated with prolonged and dysfunctional labor and significant risk of emergency cesarean section. We investigated the influence of maternal age on myometrial contractility, expression of contractile associated proteins (CAPs), and global gene expression in the parturient uterus. Female Wistar rats either 8 (YOUNG n = 10) or 24 (OLDER n = 10) weeks old were fed laboratory chow, mated, and killed during parturition. Myometrial strips were dissected to determine contractile activity, cholesterol (CHOL) and triglycerides (TAG) content, protein expression of connexin-43 (GJA1), prostaglandin-endoperoxide synthase 2 (PTGS2), and caveolin 1 (CAV-1). Maternal plasma concentrations of prostaglandins PGE2, PGF2α, and progesterone were determined by RIA. Global gene expression in uterine samples was compared using Affymetrix Genechip Gene 2.0 ST arrays and Ingenuity Pathway analysis (IPA). Spontaneous contractility in myometrium exhibited by YOUNG rats was threefold greater than OLDER animals (P < 0.027) but maternal age had no significant effect on myometrial CAP expression, lipid profiles, or pregnancy-related hormones. OLDER myometrium increased contractile activity in response to PGF2α, phenylephrine, and carbachol, a response absent in YOUNG rats (all P < 0.002). Microarray analysis identified that maternal age affected expression of genes related to immune and inflammatory responses, lipid transport and metabolism, steroid metabolism, tissue remodeling, and smooth muscle contraction. In conclusion YOUNG laboring rat myometrium seems primed to contract maximally, whereas activity is blunted in OLDER animals and requires stimulation to meet contractile potential. Further work investigating maternal age effects on myometrial function is required with focus on lipid metabolism and inflammatory pathways.

The role of cellular coupling in the spontaneous generation of electrical activity in uterine tissue

The spontaneous emergence of contraction-inducing electrical activity in the uterus at the beginning of labor remains poorly understood, partly due to the seemingly contradictory observation that isolated uterine cells are not spontaneously active. It is known, however, that the expression of gap junctions increases dramatically in the approach to parturition, by more than one order of magnitude, which results in a significant increase in inter-cellular electrical coupling. In this paper, we build upon previous studies of the activity of electrically excitable smooth muscle cells (myocytes) and investigate the mechanism through which the coupling of these cells to electrically passive cells results in the generation of spontaneous activity in the uterus. Using a recently developed, realistic model of uterine muscle cell dynamics, we investigate a system consisting of a myocyte coupled to passive cells. We then extend our analysis to a simple two-dimensional lattice model of the tissue, with each myocyte being coupled to its neighbors, as well as to a random number of passive cells. We observe that different dynamical regimes can be observed over a range of gap junction conductances: at low coupling strength, corresponding to values measured long before delivery, the activity is confined to cell clusters, while the activity for high coupling, compatible with values measured shortly before delivery, may spread across the entire tissue. Additionally, we find that the system supports the spontaneous generation of spiral wave activity. Our results are both qualitatively and quantitatively consistent with observations from in vitro experiments. In particular, we demonstrate that the increase in inter-cellular electrical coupling observed experimentally strongly facilitates the appearance of spontaneous action potentials that may eventually lead to parturition.

The association between maternal biomarkers and pathways to preterm birth in twin pregnancies

OBJECTIVE

We sought to estimate the association between cervical length (CL) and fetal fibronectin (fFN) and each pathway leading to preterm birth in twin pregnancies.

METHODS

Cohort study of 560 patients with twin pregnancies who underwent routine serial CL and fFN screening from 22 to 32 weeks in one maternal fetal medicine practice during 2005-2013. We calculated the association between a short CL (≤20 mm) or positive fFN with overall preterm birth <32 weeks, and then subdivided the analysis into preterm birth <32 weeks from preterm labor, preterm premature rupture of membranes (PPROM) and indicated causes. We excluded cases of monochorionic-monoamniotic placentation, vasa previa, twin-twin transfusion and patients with cerclage.

RESULTS

The overall rate of preterm birth <32 weeks was 6.9% (3.9% from preterm labor, 1.6% from PPROM and 1.4% indicated). A short cervix was associated with preterm birth <32 weeks arising from preterm labor (12.4% versus 2.0%, p < 0.001), but not PPROM (1.9% versus 1.3%, p = 0.651). Positive fFN was associated with preterm birth <32 weeks both from preterm labor (17.0% versus 2.4%, p < 0.001) as well as from PPROM (5.7% versus 1.0%, p = 0.034). Neither was significantly associated with preterm birth <32 weeks from indicated causes.

CONCLUSIONS

The mechanism leading toward preterm influences the accuracy of screening tests chosen to assess risk in twin pregnancies. A shortened cervical length and positive fFN is associated with spontaneous preterm labor and birth <32 weeks. However, PPROM does not appear to be preceded by a short cervix, but is preceded by a positive fFN. Neither test is associated with an indicated preterm birth.

Inhibitory effect of progesterone on cervical tissue formation in a three-dimensional culture system with human cervical fibroblasts

Progesterone supplementation is recommended to prevent preterm birth in women with a short cervix, but the mechanism is unclear. We hypothesize that progesterone acts by altering the composition of the cervical extracellular matrix (ECM). We tested this hypothesis using human cervical fibroblasts in both two-dimensional (2D) and three-dimensional (3D) cultures. For 2D culture, cells were seeded in 6-well plates and cultured with media supplemented with estradiol (10(-8) M), progesterone (10(-7) or 10(-6) M), and vehicle. For 3D culture, the cells were cultured on a porous silk protein scaffold system. Progesterone and estrogen receptors were documented by immunohistochemistry and Western blot analysis. In both 2D and 3D cultures, decreased collagen synthesis was seen with increased progesterone concentration. Three-dimensional cultures could be maintained significantly longer than 2D cultures, and the morphology of 3D cultures appeared similar to native cervical tissue. Thus, further studies were performed in 3D culture. To determine the effect of progesterone concentration, the 3D scaffolds were cultured with estradiol (10(-8) M) and five conditions: vehicle; 10(-9), 10(-8), or 10(-7) M progesterone; or 10(-7) M progesterone plus 10(-6) M mifepristone. The highest progesterone concentration correlated with the least amount of collagen synthesis. Collagen synthesis progressively increased as progesterone concentration decreased. This effect was partially antagonized by mifepristone, suggesting the mechanism is mediated by the progesterone receptor. This hormonally responsive 3D culture system supports the hypothesis that progesterone has a direct effect on remodeling cervical ECM during pregnancy. The 3D culture system could be useful for studying the mechanism of progesterone effects on the cervix.

Is vitamin D binding protein a novel predictor of labour?

Vitamin D binding protein (VDBP) has previously been identified in the amniotic fluid and cervicovaginal fluid (CVF) of pregnant women. The biological functions of VDBP include acting as a carrier protein for vitamin D metabolites, the clearance of actin that is released during tissue injury and the augmentation of the pro-inflammatory response. This longitudinal observational study was conducted on 221 healthy pregnant women who spontaneously laboured and delivered either at term or preterm. Serial CVF samples were collected and VDBP was measured by ELISA. Binary logistic regression analysis was performed to assess the utility of VDBP as a predictor of labour. VDBP in the CVF did not change between 20 and 35 weeks' gestation. VDBP measured in-labour was significantly increased 4.2 to 7.4-fold compared to 4-7, 8-14 and 15-28 days before labour (P<0.05). VDBP concentration was 4.3-fold significantly higher at 0-3 days compared to 15-28 days pre-labour (P<0.05). The efficacy of VDBP to predict spontaneous labour onset within 3 days provided a positive and negative predictive value of 82.8% and 95.3% respectively (area under receiver operator characteristic curve  = 0.974). This longitudinal study of pregnant women suggests that VDBP in the CVF may be a useful predictor of labour.

Comparison of the mechanisms responsible for cervical remodeling in preterm and term labor

Understanding the mechanisms of term and preterm cervical remodeling is essential to prevent prematurity. Is preterm cervical remodeling caused by the same mechanisms that cause cervical remodeling at term, and are these changes accelerated in time? This question has been pondered by obstetricians seeking strategies to prevent preterm labor for many years. Mice represent an informative model of preterm birth. Thus, in this review we discuss the recent findings from mouse models that identify and characterize the initiators and cellular effectors of cervical remodeling at term and preterm labor/delivery. These studies suggest that similarities and differences exist between term and preterm cervical remodeling. Complement is an initiator or mediator in preterm labor/delivery, but is not involved in the physiological process that leads to term delivery. Therefore, complememt constitutes a specific and selective target for potentially preventing preterm delivery, thus improving neonatal health.

Development and validation of primary human myometrial cell culture models to study pregnancy and labour

Background

The development of the in vitro cell culture model has greatly facilitated the ability to study gene expression and regulation within human tissues. Within the human uterus, the upper (fundal) segment and the lower segment may provide distinct functions throughout pregnancy and during labour. We have established primary cultured human myometrial cells, isolated from both upper and lower segment regions of the pregnant human uterus, and validated them for the purpose of studying human pregnancy and labour. The specific objectives of this study were to monitor the viability and characterize the expression profile using selected cellular, contractile and pregnancy associated markers in the primary cultured human myometrial cells. Labour has been described as an inflammatory process; therefore, the ability of these cells to respond to an inflammatory stimulus was also investigated.

Methods

Myometrial cells isolated from paired upper segment (US) and lower segment (LS) biopsies, obtained from women undergoing Caesarean section deliveries at term prior to the onset of labour, were used to identify expression of; α smooth muscle actin, calponin, caldesmon, connexin 43, cyclo-oxygenase-2 (COX-2), oxytocin receptor, tropomyosin and vimentin, by RT-PCR and/or immunocytochemistry. Interleukin (IL)-1β was used to treat cells, subsequently expression of COX-2 mRNA and release of interleukin-8 (CXCL8), were measured. ANOVA followed by Bonferroni’s multiple comparisons test was performed.

Results

We demonstrate that US and LS human myometrial cells stably express all markers examined to at least passage ten (p10). Connexin 43, COX-2 and vimentin mRNA expression were significantly higher in LS cells compared to US cells. Both cell populations respond to IL-1β, demonstrated by a robust release of CXCL8 and increased expression of COX-2 mRNA from passage one (p1) through to p10.

Conclusions

Isolated primary myometrial cells maintain expression of smooth muscle and pregnancy-associated markers and retain their ability to respond to an inflammatory stimulus. These distinct myometrial cell models will provide a useful tool to investigate mechanisms underlying the process of human labour and the concept of functional regionalization of the pregnant uterus.

Prostaglandin-induced cervical remodelling in humans in the first trimester is associated with increased expression of specific tight junction, but not gap junction proteins

Background

Prostaglandins (PG) are widely employed to induce cervical remodelling (CR) in pregnancy. However, the underlying molecular mechanisms are not fully elucidated. Tight junctions (TJ) and gap junctions (GJ) regulate paracellular and intercellular solute transport respectively but their role in the process of CR remains unexplored. We hypothesized that the synthetic prostaglandin E1 analogue Misoprostol (M), widely used in clinical practice to induce CR, may alter TJ and GJ expression as part of the changes in the extracellular matrix (ECM) associated with remodelling. We investigated the effects of Misoprostol exposure on the expression of cervical TJ (claudins 1, 2, 4, 5, 7 and occludin) and GJ (connexins 43, 30 and 26) in the 1st trimester.

Methods

Cervical biopsies were obtained from pregnant women and comparisons of TJ and GJ protein expression (by western blotting) and immunolocalisation (laser scanning confocal microscopy) made between those who were administered vaginal Misoprostol (n = 10) and those who were not (n = 5).

Results

We found that Misoprostol-treated tissue (M+) had higher expression of Claudins 1,2,4,7 and occludin (p < 0.05) than untreated (M-) tissue. Expression levels of Claudins 1, 2 and 4 were positively correlated to interval from Misoprostol treatment to biopsy, whilst occludin was negatively correlated. Misoprostol-treated cervical tissue demonstrated more endothelial claudin-5 and occludin, whilst expression of GJs were unchanged.

Conclusion

Our observations suggest, for the first time, that increased expression of tight junction proteins may be one of the mechanisms by which Misoprostol induces CR in humans. Further studies are needed to explore if TJ proteins may be therapeutic targets to alter timing of CR in clinical practice.

High iNOS mRNA and protein localization during late pregnancy suggest a role for nitric oxide in mouse pubic symphysis relaxation

Remodeling and relaxation of the mouse pubic symphysis (PS) are central events in parturition. The mouse PS remodels in a hormone-controlled process that involves the modification of the fibrocartilage into an interpubic ligament (IpL), followed by its relaxation prior to parturition. It is recognized that nitric oxide synthase (NOS) and consequently nitric oxide (NO) generation play important roles in extracellular matrix modification, and may promote cytoskeleton changes that contribute to the remodeling of connective tissue, which precedes the onset of labor. To our knowledge, no studies thus far have investigated inducible nitric oxide synthase (iNOS) expression, protein localization, and NO generation in the mouse PS during pregnancy. In this work, we used a combination of the immunolocalization of iNOS, its relative mRNA expression, and NO production to examine the possible involvement of iNOS in remodeling and relaxation of the mouse IpL during late pregnancy. The presence of iNOS was observed in chondrocytes and fibroblast-like cells in the interpubic tissues. In addition, iNOS mRNA and NO production were higher during preterm labor on Day 19 of pregnancy (D19) than NO production on D18 or in virgin groups. The significant increase in iNOS mRNA expression and NO generation from the partially relaxed IpL at D18 to the completely relaxed IpL at D19 may indicate that NO plays an important role in late pregnancy during relaxation of the mouse IpL.

Cervical remodeling/ripening at term and preterm delivery: the same mechanism initiated by different mediators and different effector cells

BACKGROUND

Premature cervical remodeling/ripening is believed to contribute to preterm delivery (PTD), the leading cause of perinatal morbidity and mortality. Despite considerable research, the causes of term and PTD remain unclear, and there is no effective treatment for PTD. We previously demonstrated that complement activation plays a causative role in cervical remodeling that leads to PTD in mice.

METHODOLOGY/PRINCIPAL FINDINGS

Here we found that complement activation is not required for the physiological process that leads to term delivery in mice. Neither increased C3 cervical deposition nor increased C3a and C5a serum levels were observed at term. In addition, macrophages infiltration was found in PTD in contrast to term delivery were no leukocytes were found. Despite the different role of complement and different cellular effector cells, PTD and term delivery share a common dowsntream pathway characterized by increased metalloproteinases (MMPs) release and increased collagen degradation. However, different sources of MMPs were identified. Macrophages are the source of MMPs in PTD while cervical fibroblasts and columnar epithelial cells synthesize MMPs at term delivery. A dramatic diminution in serum progesterone levels precedes parturition at term but not in PTD, suggesting that progesterone withdrawal initiates cervical remodeling at term. On the other hand, MMPs release in PTD is triggered by C5a.

CONCLUSION AND SIGNIFICANCE

In conclusion, preterm and term cervical remodeling occur through the same mechanism but they are initiated by different mediators and effector cells. That complement activation is required for PTD but not for the physiological process that leads to term delivery, suggests that complement is a potential specific biomarker and selective target to prevent PTD and thus avert neonatal mortality and morbidity.

Progesterone interactions with the cervix: translational implications for term and preterm birth

The uterine cervix plays a vital role in maintaining pregnancy and an equally important role in allowing parturition to occur. Progesterone, either endogenously produced or supplied exogenously, supports the function of the cervix in sustaining intrauterine pregnancy, and the withdrawal of progesterone, either through natural processes or pharmacologic intervention, leads to delivery which underscores the importance of the progesterone's biological activities manifest in normal gestation and pregnancy that ends prematurely. Research crossing many scientific disciplines has demonstrated that progesterone is a pleotropic compound that affects the cervix through cytoplasmic and membrane receptors with profound effects on cellular and molecular functions that influence inflammatory cascades and extracellular matrix, both of which have consequences for parturition. Beyond the local cell and molecular biology of progesterone, it has systemic effects of relevance to pregnancy as well. This paper examines the biology of the cervix from its gross to cellular structure and biological activities of its cell and molecular processes that may be affected by progesterone. The implications of these processes for preterm birth are explored, and direction of current research is in relation to translational medicine implications for diagnostic, prognostic, and therapeutic approaches to threatened preterm birth.

A novel isoform of microphthalmia-associated transcription factor inhibits IL-8 gene expression in human cervical stromal cells

Cervical ripening during pregnancy is a profound change in cervix structure and function characterized by increases in the proinflammatory cytokine IL-8 and dissolution of the cervical extracellular matrix. Relatively little is known about the molecular mechanisms that underlie these events. Here, we report identification of a novel isoform of micropthalmia-associated transcription factor in human cervical stromal cells (MiTF-CX) that is down-regulated 12-fold during cervical ripening and that represses expression of IL-8. Ectopic expression of MiTF-CX in human cervical stromal cells resulted in substantial suppression of endogenous IL-8 mRNA and protein expression, whereas expression of dominant negative MiTF-CX mutants with impaired DNA binding resulted in dramatic increases in IL-8 production. Gel shift, reporter gene, and chromatin immunoprecipitation assays revealed one strong binding site (E-box (-397) CACATG(-391)) in the human IL-8 promoter that was crucial for mediating transcriptional repression by MiTF-CX. Moreover, we show that MiTF-CX expression in the cervix was itself positively autoregulated via two E-box motifs within a 2.1-kb promoter fragment. We therefore propose that maintenance of cervical competency during pregnancy is an active process maintained through suppression of IL-8 by the transcription factor MiTF-CX. During cervical ripening, loss of MiTF-CX would result in significant up-regulation of IL-8 mRNA and protein synthesis, thereby leading to recruitment and activation of leukocytes within the cervix and dissolution of the extracellular matrix.

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.

Fibroblasts-a diverse population at the center of it all

The capacity of fibroblasts to produce and organize the extracellular matrix and to communicate with other cells makes them a central component of tissue biology. Even so, fibroblasts remain a somewhat enigmatic population. Our inability to fully comprehend these cells is in large part due to the paucity of unique cellular markers and to their pervasive diversity. Much of our understanding of fibroblast diversity has evolved from studies where subpopulations of these cells have been produced without resorting to cell surface markers. In this regard, cloning and mechanical separation of tissues prior to establishing cultures has provided multiple subpopulations. Nonetheless, in isolated situations, the expression or lack of expression of Thy-1/CD90 has been used to separate fibroblast subsets. The role of fibroblasts in intercellular communication is emerging through the implementation of organotypic studies in which three-dimensional fibroblast culture are combined with other populations of cells. Such studies have revealed critical paracrine loops that are essential for organ development and for wound repair. These studies also provide a backdrop for the emerging field of tissue engineering. The participation of fibroblasts in the regulation of tissue homeostasis and their contribution to the aging process are emerging issues that require better understanding. In short, fibroblasts represent a multifaceted, complex group of cells.

Smooth muscle cells of the bovine cervical stroma may have a secretory, rather than a contractile function during parturition

The bovine cervix contains a large amount of smooth muscle cells distributed over an outer muscular layer and within a stromal layer. The stromal layer exhibits no electromyographic (EMG) activity at parturition. This leads to the question whether the stromal smooth muscle cells of the bovine cervix are prepared to contract with parturition, or whether they have another function. To this end, cervical biopsies were repeatedly taken from 10 pregnant cows at day-185 and -275 of gestation, at spontaneous, uncomplicated calving and at 30 days after calving. The smooth muscle bundles of the stroma were immunohistochemically analysed (n = 5) with regard to their integrity and cellular density, and the degree of staining for connexin-43, smooth muscle actin alpha (SMA), desmin and vimentin. Additionally, the mRNA expression for connexin-43, SMA, desmin and vimentin was determined with RT-PCR (n = 5). The smooth muscle tissue was arranged in bundles, also at parturition. However, the cellular density of these bundles and the SMA mRNA expression were decreased at parturition. Additionally, the SMA staining and connexin-43 expression and staining remained constant during pregnancy and at parturition. This might indicate that stromal smooth muscle cells are not prepared to contract with parturition, in contrast to the myometrial smooth muscle cells. The smooth muscle cells, stained for SMA, also expressed vimentin, and the proportion of co-expression was increased at day-275 of pregnancy. This suggests that the stromal smooth muscle cells predominantly have a secretory function in cows.

The hormonal induction of cervical remodeling in the common marmoset monkey (Callithrix jacchus)

Controversy still exists regarding the involvement of relaxin (RLX) in cervical reorganization throughout parturition in the human, despite its well-known role in facilitating extensive extracellular matrix (ECM) remodeling in diverse organs. Therefore, the aim of the present study was to examine the influence of RLX and estrogen (E2) on the cervical tissue of the common marmoset monkey. Two experimental designs were used: 1)in vivoanalysis of the intracervical diameter under locally applied RLX and 2) ovariectomized (ov) marmosets were treated systemically with either recombinant human (rh) RLX, E2 or rhRLX+E2 to examine their action on the cervix.In vivo-locally applied rhRLX induced a distinct and significant widening of the cervix (before: 4.8±1.1 mm versus after: 5.7±0.9 mm in diameter;P<0.030, MV±s.e.m.). This widening effect was most pronounced in animals without previous pregnancies.In vitroinvestigation of cervical tissue showed significantly increased wet weights after all three hormone treatments (E2: 0.27±0.07 g, RLX: 0.25±0.04 g, E2+RLX: 0.30±0.11 g; allP<0.05; MV±s.e.m.) versus controls (0.10±0.04 g). Furthermore, morphological changes such as loosening of the connective tissue structure and decline in collagen content, an increase in the number of eosinophils, increased the expression of matrix metalloproteinases (MMP1) and MMP2, as well as gene and protein expression of the RLX receptor RXFP1 could be detected in the cervical tissue after all hormone treatments, compared with controls. In summary, RLX has a potent widening effect on the cervix of the common marmoset monkey. Although E2 is not required for this RLX effect, a combined application of E2 and RLX induced the most prominent cervical ripening.

MMP-2 expression precedes the final ripening process of the bovine cervix

Collagen is denatured in the gradual cervical ripening process during late pregnancy, already before the onset of final cervical ripening at parturition. Matrix Metallo Proteinases (MMPs) might be responsible for this process. To investigate the presence and potential function of MMPs at the different stages of the ripening process, serial cervical biopsies were obtained from 10 cows at Days 185 and 275 of pregnancy (approximately 5 days before calving), at parturition and at 30 days after parturition. The mRNA and protein expression of MMP-1, MMP-2, and MMP-9 and of the tissue inhibitors of MMPs (TIMP)-1 and TIMP-2 were semi-quantitatively determined using RT-PCR, respectively, zymography, Westernblot, and ELISA techniques and the localization of MMP-2 protein and presence of granulocytes by immunohistochemistry and Luna staining. At parturition compared to 185 days pregnancy the MMP-1 protein expression and the numbers of granulocytes were significantly increased by 3 and 26-fold respectively. MMP-2 mRNA and protein expression had already increased 2.5 (P < 0.05) and twofold (P < 0.05) at 5 days before parturition, prior to final ripening. At that time, MMP-2 was present in smooth muscle cells and extra cellular matrix. TIMP-1 mRNA expression was significantly increased at parturition and TIMP-2 mRNA expression peaked at 5 days before parturition. The increased expression of MMP-2 at 5 days before parturition, suggests that in the cow MMP-2 is responsible for collagen denaturation in the last part of gradual cervical ripening, while MMP-1 and MMP-9 are only active during the final cervical ripening process at parturition.

Different secretion patterns of matrix metalloproteinases and IL-8 and effect of corticotropin-releasing hormone in preterm and term cervical fibroblasts

The aims of the present study were to compare the levels of mRNA and protein expression of matrix metalloproteinase (MMP)-1, -3, -8 and -9 in human cervical tissue in preterm and term labor as well as not in labor and to determine if corticotropin-releasing hormone (CRH) has an effect on MMP-1, -3 and interleukin (IL)-8 secretion in both preterm and term cervical fibroblasts. Cervical biopsies were taken from 60 women: 18 at preterm labor, 7 at preterm not in labor, 18 at term labor and 17 at term not in labor. ELISA and Immulite were used for protein and real-time RT–PCR for mRNA analysis. Cervical fibroblast cultures were incubated for 18 h with different CRH concentrations (10⁻¹³–10⁻⁶ M). The mRNA expression of MMP-1, -3 and -9 was higher in laboring groups compared with term not in labor. Protein levels of MMP-8 and -9 were higher in term in labor group compared with non-laboring groups. There were no significant differences in mRNA and protein expression between the preterm and respective term control groups. CRH significantly increased secretion of IL-8 in preterm and term cervical fibroblasts compared with controls. The secretion of IL-8 and MMP-1 was significantly higher and MMP-3 secretion lower in preterm cervical fibroblasts. In conclusion, cervical ripening at preterm seems to be a similar inflammatory process as at term with CRH involved. However, preterm and term cervical fibroblasts might have different phenotypes based on different secretion patterns of IL-8, MMP-1 and MMP-3.

Impaired leukocyte influx in cervix of postterm women not responding to prostaglandin priming

BACKGROUND

Prolonged pregnancies are associated with increased rate of maternal and fetal complications. Post term women could be divided into at least two subgroups, one where parturition is possible to induce by prostaglandins and one where it is not. Our aim was to study parameters in cervical biopsies in women with spontaneous delivery at term (controls) and compare to those that are successfully induced post term (responders), and those that are not induced (non-responders), by local prostaglandin treatment.

METHODS

Stromal parameters examined in this study were the accumulation of leukocytes (CD45, CD68), mRNAs and/or proteins for the extracellular matrix degrading enzymes (matrix metalloproteinase (MMP)-2, MMP-8 and MMP-9), their inhibitors (tissue inhibitor of MMP (TIMP)-1 and TIMP-2), interleukin-8 (IL-8), the platelet activating factor-receptor (PAF-R), syndecan-1 and estrogen binding receptors (estrogen receptor (ER)alpha, ERbeta and G-coupled protein receptor (GPR) 30) as well as the proliferation marker Ki-67.

RESULTS

The influx of leukocytes as assessed by CD45 was strongest in the responders, thereafter in the controls and significantly lower in the non-responders. IL-8, PAF-R and MMP-9, all predominantly expressed in leukocytes, showed significantly reduced immunostaining in the group of non-responders, while ERalpha and GPR30 were more abundant in the non-responders, as compared to the controls.

CONCLUSION

The impaired leukocyte influx, as reflected by the reduced number of CD45 positive cells as well as decreased immunostaining of IL-8, PAF-R and MMP-9 in the non-responders, could be one explanation of the failed ripening of the cervix in post term women. If the decreased leukocyte influx is a primary explanation to absent ripening or secondary, as a result of other factors, is yet to be established.

Cytokine networks and the regulation of uterine function in pregnancy and parturition

Complex cytokine networks play an important role in a wide range of reproductive and pregnancy related processes. Here, we review the current knowledge concerning the impact of cytokines on uterine physiology and pathophysiology. Cytokines influence a range of uterine functions during the menstrual cycle, implantation, pregnancy and labour. The synergistic interactions between individual cytokines are intricate and dynamic, and modulated by pregnancy hormones. It is not surprising therefore, that perturbations to cytokine signalling are associated with adverse pregnancy outcomes, such as miscarriage, pre-eclampsia, preterm labour and foetal brain injury. Further insight into the complexity of cytokine networks will be required to develop novel therapeutic strategies for the treatment of cytokine imbalances in pregnancy.