The effects of thrombin and cytokines upon the biomechanics and remodeling of isolated amnion membrane, in vitro

Angiogenic imbalance in pregnancies with preterm prelabor rupture of membranes between 34 and 37 weeks of gestation

INTRODUCTION

This study aimed to identify whether microbial invasion of the amniotic cavity and/or intra-amniotic inflammation in women with late preterm prelabor rupture of membranes (PPROM) was associated with changes in concentrations of soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF) and its ratio in maternal serum, and whether placental features consistent with maternal vascular malperfusion further affect their concentrations.

MATERIAL AND METHODS

This historical study included 154 women with singleton pregnancies complicated by PPROM between gestational ages 34+0 and 36+6 weeks. Transabdominal amniocentesis was performed as part of standard clinical management to evaluate the intra-amniotic environment. Women were categorized into two subgroups based on the presence of microorganisms and/or their nucleic acids in amniotic fluid (determined by culturing and molecular biology method) and intra-amniotic inflammation (by amniotic fluid interleukin-6 concentration evaluation): (1) those with the presence of microorganisms and/or inflammation (at least one present) and (2) those with negative amniotic fluid for infection/inflammation (absence of both). Concentrations of sFlt-1 and PlGF were assessed using the Elecsys® sFlt-1 and Elecsys® PlGF immunoassays and converted into multiples of medians.

RESULTS

Women with the presence of microorganisms and/or inflammation in amniotic fluid had lower serum concentrations of sFlt-1 and sFlt-1/PlGF ratios and higher concentrations of PlGF compared with those with negative amniotic fluid. (sFlt-1: presence: median 1.0 multiples of the median (MoM), vs negative: median: 1.5 MoM, P = 0.003; PlGF: presence: median 0.7 MoM, vs negative: median 0.4 MoM, P = 0.02; sFlt-1/PlGF: presence: median 8.9 vs negative 25.0, P = 0.001). Higher serum concentrations of sFlt-1 and sFlt-1/PlGF ratios as well as lower concentrations of PlGF were found in the subsets of women with maternal vascular malperfusion than in those without maternal vascular malperfusion.

CONCLUSIONS

Among women experiencing late PPROM, angiogenic imbalance in maternal serum is primarily observed in those without both microbial invasion of the amniotic cavity and intra-amniotic inflammation. Additionally, there is an association between angiogenic imbalance and the presence of maternal vascular malperfusion.

The role of placental insufficiency in spontaneous preterm birth: A literature review

Preterm Birth (delivery before 37 weeks of gestation) is the leading cause of childhood mortality and is also associated with significant morbidity both in the neonatal period and beyond. The aetiology of spontaneous preterm birth is unclear and likely multifactorial incorporating factors such as infection/inflammation and cervical injury. Placental insufficiency is emerging as an additional contributor to spontaneous preterm delivery; however, the mechanisms by which this occurs are not fully understood. Serum biomarkers and imaging techniques have been investigated as potential predictors of placental insufficiency, however none have yet been found to have a sufficient predictive value. This review examines the evidence for the role of the placenta in preterm birth, preterm prelabour rupture of the membranes and abruption as well as highlighting areas where further research is required.

Preterm membranes are mechanically more resistant than term membranes

OBJECTIVE

To compare the biomechanical properties of fetal preterm membranes (20 + 0 weeks to 30 + 0 weeks) to those of the term (37 + 0 to 41 + 0 weeks).

METHOD

Amnion and chorion were manually separated and samples were cut to the required geometry. Rectangular samples with (mode 1) and without (uniaxial) a notch, were tested for tearing energy, critical elongation, and tangent stiffness. Suture retention and inter-suture distance testing investigated the effect of suture placement.

RESULTS

From the 15 preterm and 10 term placentas studied, no notable differences were observed in uniaxial testing. Mode 1 fracture testing showed a difference in tearing energy between the preterm and term chorion (0.025 ± 0.005 vs. 0.017 ± 0.005 J/m-1 ; p = 0.027) but not in the amnion (0.030 ± 0.017 vs. 0.029 ± 0.009 J/m-1 ; p = 0.895). Both preterm amnion and chorion showed a higher critical elongation compared with term (1.229 ± 0.057 vs. 1.166 ± 0.046; p = 0.019 and 1.307 ± 0.049 vs. 1.218 ± 0.058; p = 0.012). Preterm amnion had a higher suture retention strength than its term counterpart (0.189 ± 0.065 vs. 0.121 ± 0.031 N; p = 0.023). In inter-suture distance tests, no significant interaction was observed beyond 3 mm, but the preterm chorion showed less interaction at 1-2 mm distances.

CONCLUSION

Preterm membranes have equivalent or superior tensile properties to term membranes. The chorion appears to contribute to the mechanical integrity of fetal membranes, particularly in preterm stages.

Characteristic impairment of progesterone response in cultured cervical fibroblasts obtained from patients with refractory cervical insufficiency

Preterm birth (PTB) is the leading cause of neonatal mortality, and reducing the PTB rate is one of the most critical issues in perinatal medicine. Cervical insufficiency (CI), a major cause of PTB, is characterised by premature cervical ripening in the second trimester, followed by recurrent pregnancy loss. Although multiple clinical trials have suggested that progesterone inhibits cervical ripening, no studies have focused on progesterone-induced molecular signalling in CI. Here, we established a primary culture system for human uterine cervical fibroblasts using a sample of patients with refractory innate CI who underwent transabdominal cervical cerclage and patients with low Bishop scores who underwent elective caesarean section as controls. RNA sequencing showed that the progesterone response observed in the control group was impaired in the CI group. This was consistent with the finding that progesterone receptor expression was markedly downregulated in CI. Furthermore, the inhibitory effect of progesterone on lipopolysaccharide-induced inflammatory stimuli was also impaired in CI. These results suggest that abnormal cervical ripening in CI is caused by the downregulation of progesterone signalling at the receptor level, and provide a novel insight into the molecular mechanism of PTB.

The serotonin reuptake inhibitor fluoxetine induces human fetal membrane sterile inflammation through p38 MAPK activation

Serotonin Reuptake Inhibitors (SRIs) are often used as first line therapy for depression and other psychiatric disorders. SRI use during pregnancy is associated with preterm premature rupture of membranes (PPROM) and subsequent preterm birth. The objective of this study was to investigate the mechanism(s) responsible for SRI-associated PPROM. Putative mechanisms underlying PPROM include fetal membrane (FM) inflammation, increased apoptosis, and/or accelerated senescence, the later which may be reversed by statins. Human FM explants from normal term deliveries without labor, infection, or antidepressant use were treated with or without the SRI, fluoxetine (FLX), either alone or in the presence of a p38 MAPK inhibitor or the statins, simvastatin or rosuvastatin. FMs were also collected from women either unexposed or exposed to FLX during pregnancy. FLX significantly increased FM p38 MAPK activity and secretion of inflammatory IL-6. Inhibition of p38 MAPK reduced FM IL-6 secretion in response to FLX. Statins did not reduce the SRI-induced FM IL-6 production. FMs from women exposed to FLX during pregnancy expressed elevated levels of p38 MAPK activity compared to matched unexposed women. FMs exposed to FLX did not exhibit signs of increased apoptosis and/or accelerated senescence. These results indicate that the SRI, FLX, may induce sterile FM inflammation during pregnancy through activation of the p38 MAPK pathway, and in the absence of apoptosis and senescence. These findings may better inform clinicians and patients as they weigh the risks and benefits of SRI antidepressant treatment during pregnancy.

The Effect of Antenatal Steroid Therapy on Early Inflammation Markers and Leukocyte Counts in Premature Infants

ObjectiveWe investigated the effect of antenatal steroid therapy(AST) on white blood cell (WBC) and neutrophil counts and the inflammatory markers C-reactive protein(CRP), interleukin 6(IL-6), interleukin 10(IL-10), and beta-2 microglobulin(ß2M) in preterm infants.Materials MethodNeonates born at ≤34 weeks of gestation and admitted at hospital between May and November 2018 were included. The neonates were divided into three groups based on AST dose administered: 24 mg betamethasone (full course), 12 mg betamethasone (incomplete course), and no AST. 170 infants were analyzed.ResultsOf these, 45.2% (n = 77) received a full course of AST, 38.8% (n = 66) received an incomplete course of AST, and 15.8% (n = 27) did not receive AST. WBC, CRP, IL-6, IL-10, and ß2M levels were similar between the three groups, whereas neutrophil count was significantly lower in full course AST group.ConclusionConsistent with the literature data, AST was associated with reduced neutrophil count but did not affect the other inflammatory markers studied.

Utero-Placental Immune Milieu during Normal and Aglepristone-Induced Parturition in the Dog

Simple Summary

The tolerance of the maternal immune system towards the embryo is essential for the success of pregnancy in all mammals. The uterine immunological milieu is modulated in a species-dependent manner, and pro-inflammatory responses are observed in the uterus during parturition in several species. An analogous situation was suggested for the dog. Nevertheless, details regarding immune signaling in the canine utero-placental compartments remain veiled. The present investigation of gene expression and immunolocalization of several immune-related factors revealed moderate utero-placental activity during mid-pregnancy (maintenance period). However, several immune factors were upregulated during parturition, suggesting an increased incidence of cells involved in tissue remodeling and/or immune regulation. The involvement of progesterone in these mechanisms was further assessed by using samples from mid-pregnant dogs treated with the progesterone receptor blocker, aglepristone. Similarities were observed in the expression pattern of several immune factors between natural and induced parturition, supporting the involvement of progesterone signaling in the modulation of the uterine immune milieu. This study provides the basis for further investigations regarding the immune regulation of parturition in the dog. Furthermore, differences observed between natural and induced parturition could be related to different placental maturation and/or functional characteristics of aglepristone, and might be of clinical relevance.

Abstract

Maternal immunotolerance is required for the maintenance of pregnancy, in sharp contrast with the uterine pro-inflammatory activity observed during parturition in several species. Correspondingly, in the dog, increased immune signaling at term has been suggested, but a deeper understanding of the uterine immune milieu is still missing. Thus, the availability of 30 immune-related factors was assessed in utero-placental samples collected during post-implantation (days 18–25 of pregnancy) and mid-gestation (days 35–40) stages, and at the time of prepartum luteolysis. Gene expression and/or protein localization studies were employed. Samples collected from antigestagen (aglepristone)-treated dogs were further analyzed. Progression of pregnancy was associated with the downregulation of IL1β and upregulation of IL10 (p < 0.05) at mid-gestation. When compared with mid-gestation, a higher availability of several factors was observed at term (e.g., CD206, CD4, TLR4). However, in contrast with natural parturition, MHCII, CD25, CCR7, TNFα, IDO1 and AIF1 were upregulated after aglepristone treatment (p < 0.05), but not TNFR1 or CCL13 (p > 0.05). Altogether, these results show an increased immune activity during canine parturition, involving, i.a., M2 macrophages, Treg and Th cells, with strong support for progesterone-mediated immunomodulation. Furthermore, differences between term and induced parturition/abortion could relate to differences in placental maturation towards parturition and/or functional traits of antigestagens.

The Role of Innate Immune System in the Human Amniotic Membrane and Human Amniotic Fluid in Protection Against Intra-Amniotic Infections and Inflammation

Intra-amniotic infection and inflammation (IAI) affect fetal development and are highly associated with preterm labor and premature rupture of membranes, which often lead to adverse neonatal outcomes. Human amniotic membrane (hAM), the inner part of the amnio-chorionic membrane, protects the embryo/fetus from environmental dangers, including microbial infection. However, weakened amnio-chorionic membrane may be breached or pathogens may enter through a different route, leading to IAI. The hAM and human amniotic fluid (hAF) respond by activation of all components of the innate immune system. This includes changes in 1) hAM structure, 2) presence of immune cells, 3) pattern recognition receptors, 4) cytokines, 5) antimicrobial peptides, 6) lipid derivatives, and 7) complement system. Herein we provide a comprehensive and integrative review of the current understanding of the innate immune response in the hAM and hAF, which will aid in design of novel studies that may lead to breakthroughs in how we perceive the IAI.

Single Nucleotide Polymorphisms from CSF2, FLT1, TFPI and TLR9 Genes Are Associated with Prelabor Rupture of Membranes

A prelabor rupture of membranes (PROM) and its subtypes, preterm PROM (pPROM) and term PROM (tPROM), are associated with disturbances in the hemostatic system and angiogenesis. This study was designed to demonstrate the role of single nucleotide polymorphisms (SNPs), localized in CSF2 (rs25881), FLT1 (rs722503), TFPI (C-399T) and TLR9 (rs352140) genes, in PROM. A population of 360 women with singleton pregnancy consisted of 180 PROM cases and 180 healthy controls. A single-SNP analysis showed a similar distribution of genotypes in the studied polymorphisms between the PROM or the pPROM women and the healthy controls. Double-SNP TT variants for CSF2 and FLT1 polymorphisms, CC variants for TLR9 and TFPI SNPs, TTC for CSF2, FLT1 and TLR9 polymorphisms, TTT for FLT1, TLR9 and TFPI SNPs and CCCC and TTTC complex variants for all tested SNPs correlated with an increased risk of PROM after adjusting for APTT, PLT parameters and/or pregnancy disorders. The TCT variants for the CSF2, FLT1 and TLR9 SNPs and the CCTC for the CSF2, FLT1, TLR9 and TFPI polymorphisms correlated with a reduced risk of PROM when corrected by PLT and APTT, respectively. We concluded that the polymorphisms of genes, involved in hemostasis and angiogenesis, contributed to PROM.

Cross talk: Trafficking and functional impact of maternal exosomes at the Feto-maternal Interface under normal and pathologic states

Fetal cell-derived exosomes promote inflammation in uterine and cervical cells to promote labor and delivery. However, the effect of maternal exosomes on fetal cells is still not known. We tested the hypothesis that cervical cells exposed to infectious and oxidative stress (OS) signals produce exosomes that can induce inflammation at the feto-maternal interface (FMi). Exosomes isolated from medium samples from human ectocervical epithelial cells (Ecto), endocervical epithelial cells (Endo), and cervical stromal cells (Stroma) in normal cell culture (control) or exposed to infection or OS conditions were characterized based on morphology, size, quantity, expression of tetraspanin markers, and cargo proteins. Human decidual, chorion trophoblast (CTC), chorion mesenchymal (CMC), amnion mesenchymal (AMC), and amnion epithelial cells (AEC) were treated with control, LPS-, or OS-treated cervical exosomes. ELISA for pro-inflammatory cytokines and progesterone was done to determine the recipient cells' inflammatory status. Ecto, endo, and stroma released ∼110 nm, cup-shaped exosomes. LPS and OS treatments did not affect exosome size; however, OS significantly increased the number of exosomes released by all cervical cells. Cervical exosomes were detected by fluorescence microscopy in each target cell after treatment. Exosomes from LPS- and CSE-treated cervical cells increased the inflammatory cytokine levels in the decidual cells, CMC, AMC, and AEC. LPS-treated stromal cell exosomes increased IL-6, IL-8, and progesterone in CTC. In conclusion, infection and OS can produce inflammatory cargo-enriched cervical exosomes that can destabilize FMi cells. However, the refractoriness of CTC to exosome treatments suggests a barrier function of the chorion at the FMi.

Inflammatory Amplification: A Central Tenet of Uterine Transition for Labor

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

Pathophysiological Implication of Pattern Recognition Receptors in Fetal Membranes Rupture: RAGE and NLRP Inflammasome

Preterm prelabor ruptures of fetal membranes (pPROM) are a pregnancy complication responsible for 30% of all preterm births. This pathology currently appears more as a consequence of early and uncontrolled process runaway activation, which is usually implicated in the physiologic rupture at term: inflammation. This phenomenon can be septic but also sterile. In this latter case, the inflammation depends on some specific molecules called “alarmins” or “damage-associated molecular patterns” (DAMPs) that are recognized by pattern recognition receptors (PRRs), leading to a microbial-free inflammatory response. Recent data clarify how this activation works and which receptor translates this inflammatory signaling into fetal membranes (FM) to manage a successful rupture after 37 weeks of gestation. In this context, this review focused on two PRRs: the receptor for advanced glycation end-products (RAGE) and the NLRP7 inflammasome.

Molecular Changes on Maternal-Fetal Interface in Placental Abruption-A Systematic Review

Placental abruption is the separation of the placenta from the lining of the uterus before childbirth. It is an infrequent perinatal complication with serious after-effects and a marked risk of maternal and fetal mortality. Despite the fact that numerous placental abruption risk factors are known, the pathophysiology of this issue is multifactorial and not entirely clear. The aim of this review was to examine the current state of knowledge concerning the molecular changes on the maternal–fetal interface occurring in placental abruption. Only original research articles describing studies published in English until the 15 March 2021 were considered eligible. Reviews, book chapters, case studies, conference papers and opinions were excluded. The systematic literature search of PubMed/MEDLINE and Scopus databases identified 708 articles, 22 of which were analyzed. The available evidence indicates that the disruption of the immunological processes on the maternal–fetal interface plays a crucial role in the pathophysiology of placental abruption. The features of chronic non-infectious inflammation and augmented immunological cytotoxic response were found to be present in placental abruption samples in the reviewed studies. Various molecules participate in this process, with only a few being examined. More advanced research is needed to fully explain this complicated process.

Impact of Progesterone on Molecular Mechanisms of Preterm Premature Rupture of Membranes

The role and mechanisms of progesterone in preterm premature rupture of membranes (PPROM) remains unclear. This study aims to investigate the molecular mechanisms of action of progesterone in pre-labor full-term fetal amniotic membrane cells with and without stimulation by microbial, pro-inflammatory, or thrombogenic agents. Fetal amniotic membranes were collected from 30 women with a normal singleton pregnancy undergoing elective cesarean section at term prior to the onset of labor. The human amniotic epithelial cells isolated were pretreated with and without medroxyprogesterone acetate for 24 h. Then, cells were treated with and without TLR/NLR agonists, pro-inflammatory cytokines, or thrombin for 48 h. Semi-quantitative RT-PCR, Western blot, and caspase-3 activity measurement were performed. Progesterone stimulation decreased the expression of TLR2, TLR5, and Nod2 genes (alone and/or in combination with TLR/NLR agonists) and decreased the expression of IL-1β and IL-8 genes increased by stimulation with specific agonists for TLR2, TLR4, TLR5, Nod1, and Nod2. Moreover, progesterone decreased thrombin-induced IL-8 gene expression. Progesterone also decreased expression of Bax and Bid proteins (pro-apoptotic factors) increased by stimulation with pro-inflammatory cytokines (TNF-α, NGAL, IL-18, and IL-1β) and thrombin. Progesterone stimulation alone as well as co-stimulation with TNF-α, NGAL, IL-18, IL-1β, or thrombin with progesterone either increased, decreased, or did not change the expression of Bcl-2, Bcl-XL, or XIAP genes (anti-apoptotic factors). These data suggest progesterone plays protective roles against PPROM through anti-microbial, anti-inflammatory, and anti-thrombogenic actions on human-term fetal amniotic membrane cells. Progesterone alters pro-inflammatory cytokine- and thrombin-induced apoptosis by controlling the expression of pro-apoptotic and anti-apoptotic factors.

Effects of histone H4 hyperacetylation on inhibiting MMP2 and MMP9 in human amniotic epithelial cells and in premature rupture of fetal membranes

Histone modification is closely associated with several diseases. The aim of the current study was to investigate the associations among histone acetylation, matrix metalloproteinases (MMPs) and premature rupture of membranes (PROM) during pregnancy. A total of 180 puerperants were divided into three groups: i) Preterm-PROM (PPROM), ii) term-PROM (TPROM) and iii) full-term labor (FTL). Enzyme-linked immunosorbent assay (ELISA) kits and western blotting were used to determine the protein concentrations of MMP2, MMP9, histone deacetylase (HDAC)1, HDAC2 and HDAC6, and the protein levels of histone H4 lysine (H4K)5 and H4K8 acetylation, respectively, in three types of fetal membranes. Additionally, human amniotic epithelial cells were used to determine the effects of the HDAC inhibitors droxinostat and chidamide on cell viability, histone acetylation and the levels of MMP2, MMP9, HDAC1, HDAC2 and HDAC6 in vitro, using the Cell Counting Kit-8 assay, western blotting and ELISA, respectively. Furthermore, the effects of droxinostat and chidamide on the invasion and migration abilities of human amniotic epithelial cells were investigated using transwell assays. In fetal membranes, the activities of MMP2 and MMP9 increased in PPROM, but decreased in TPROM. Further, the expression of HDAC1 was decreased and histone hyperacetylation was increased in both PPROM and TRPOM. In vitro experiments revealed that 5 µM droxinostat and 0.5 µM chidamide selectively decreased the level of HDAC and induced acetylation of H4K5 and H4K8. Additionally, the aforementioned HDAC inhibitors reduced human amniotic epithelial cell viability, invasion and migration, and decreased the expression levels of MMP2 and MMP9. The current study revealed a high expression level of MMP2 and MMP9 in PPROM compared with TPROM and FL tissue, which was in accordance with previously published studies. Furthermore, the in vitro tests performed in the current study revealed the effect of histone H4 hyperacetylation on inhibiting MMP2 and MMP9 levels in vitro was similar to that observed in TPROM. The results obtained in the current study may be used as a theoretical guide for clinical treatment of premature rupture of membranes.

Mechanism of Human Fetal Membrane Biomechanical Weakening, Rupture and Potential Targets for Therapeutic Intervention

Using a novel in vitro model system combining biochemical/histologic with bioengineering approaches has provided significant insights into the physiology of fetal membrane weakening and rupture along with potential mechanistic reasons for lack of efficacy of currently clinically used agents to prevent preterm premature rupture of the membranes (pPROM) and preterm births. Likewise, the model has also facilitated screening of agents with potential for preventing pPROM and preterm birth.

Novel pathways of inflammation in human fetal membranes associated with preterm birth and preterm pre-labor rupture of the membranes

Spontaneous preterm birth (PTB) and preterm pre-labor rupture of the membranes (pPROM) are major pregnancy complications. Although PTB and pPROM have common etiologies, they arise from distinct pathophysiologic pathways. Inflammation is a common underlying mechanism in both conditions. Balanced inflammation is required for fetoplacental growth; however, overwhelming inflammation (physiologic at term and pathologic at preterm) can lead to term and preterm parturition. A lack of effective strategies to control inflammation and reduce the risk of PTB and pPROM suggests that there are several modes of the generation of inflammation which may be dependent on the type of uterine tissue. The avascular fetal membrane (amniochorion), which provides structure, support, and protection to the intrauterine cavity, is one of the key contributors of inflammation. Localized membrane inflammation helps tissue remodeling during pregnancy. Two unique mechanisms that generate balanced inflammation are the progressive development of senescence (aging) and cyclic cellular transitions: epithelial to mesenchymal (EMT) and mesenchymal to epithelial (MET). The intrauterine build-up of oxidative stress at term or in response to risk factors (preterm) can accelerate senescence and promote a terminal state of EMT, resulting in the accumulation of inflammation. Inflammation degrades the matrix and destabilizes membrane function. Inflammatory mediators from damaged membranes are propagated via extracellular vesicles (EV) to maternal uterine tissues and transition quiescent maternal uterine tissues into an active state of labor. Membrane inflammation and its propagation are fetal signals that may promote parturition. This review summarizes the mechanisms of fetal membrane cellular senescence, transitions, and the generation of inflammation that contributes to term and preterm parturitions.

α-Lipoic acid blocks the GMCSF induced protease/protease inhibitor spectrum associated with fetal membrane weakening in-vitro

INTRODUCTION

We use an in-vitro human fetal membrane (FM) explant-based model to study inflammation-induced FM weakening, a prerequisite for PPROM. In this system, GMCSF is a critical intermediate, both necessary and sufficient for TNFα and thrombin induced FM weakening. α-Lipoic-acid (LA) blocks TNFα and thrombin, as well as GMCSF-induced weakening. Recently, we reported LA concomitantly blocks GMCSF-induction of MMPs 2, 9 and 10 and inhibition of TIMPs 1-3. The aim of this study was to show that LA blocks GMCSF-induced increases in additional proteases and reductions in additional protease inhibitors.

METHODS

FM fragments were cultured±LA and then±GMCSF. In other experiments, weak versus strong, fresh FM were cultured without additions. Fragments were strength tested and media analyzed by multiplex protein ELISA for proteases and protease inhibitors.

RESULTS

GMCSF induced FM weakening and concomitantly increased several Proteases (Cathepsin-S, Proteinase-3, Elastase-2) and decreased several protease inhibitors (NGAL, Cystatin-C, HE4 and Thrombospondin1). LA inhibited GMCSF-induced FM weakening and all enzymatic changes. Untreated weaker versus stronger regions of fresh FM showed comparable differences in proteases and protease inhibitor patterns to GMCSF-stimulated versus controls.

CONCLUSION

LA blocks GMCSF-induced human FM weakening and associated protease increases and inhibitor decreases. The GMCSF-induced spectrum of protease/protease-inhibitor changes is similar to that in the natural weak FM fragments. In concert with previously reported GMCSF-induced changes in MMPs & TIMPs, these other protease and protease-inhibitor changes presumably facilitate FM weakening and rupture. LA blocks these GMCSF effects and therefore may be a useful agent to prevent PPROM.

Fetal Membranes, Not a Mere Appendage of the Placenta, but a Critical Part of the Fetal-Maternal Interface Controlling Parturition

Fetal membranes (FMs) play a role in pregnancy maintenance and promoting parturition at term. The FMs are not just part of the placenta, structurally or functionally. Although attached to the placenta, the amnion has a separate embryologic origin, and the chorion deviates from the placenta by the first month of pregnancy. Other than immune protection, these FM functions are not those of the placenta. FM dysfunction is associated with and may cause adverse pregnancy outcomes. Ongoing research may identify biomarkers for pending preterm premature rupture of the FMs as well as therapeutic agents, to prevent it and resulting preterm birth.

Influence of osmolarity and hydration on the tear resistance of the human amniotic membrane

The amnion is considered to be the load-bearing part of the fetal membranes. We investigated the influence of osmolarity of the testing medium and hydration on its fracture toughness. Mode I fracture tests revealed that physiological variations in the bath osmolarity do not influence the tear resistance of amnion, while larger changes, i.e. from physiological saline solution to distilled water, lead to a significant reduction of the fracture toughness. Uniaxial tensile tests on collagen hydrogels confirmed the reduction in toughness, suggesting that lower bath osmolarity triggers changes in the failure properties of single collagen fibers. Prenatal surgeries, in particular fetoscopic procedures with partial amniotic carbon dioxide insufflation, might result in dehydration of the amnion. Dehydration induced a brittle behavior; however, subsequent rehydration for 15 min resulted in a similar tear resistance as for the fresh tissue.

Granulocyte macrophage colony stimulating factor (GM-CSF), the critical intermediate of inflammation-induced fetal membrane weakening, primarily exerts its weakening effect on the choriodecidua rather than the amnion

INTRODUCTION

We have previously demonstrated two associations of PPROM, (1) inflammation/infection (modeled by tumor necrosis factor (TNF)) and (2) decidual bleeding (modeled by thrombin), both decrease fetal membrane (FM) rupture strength in-vitro. Furthermore, Granulocyte-Macrophage-Colony-Stimulating-Factor (GM-CSF) induced by both TNF and thrombin is a critical intermediate, necessary and sufficient for weakening by either agent. The amnion is the strength component of FM and must weaken for FM to rupture. It is unclear whether GM-CSF weakens amnion (AM) directly, or initially targets choriodecidua (CD) which secondarily releases agents to act on amnion.

METHODS

Full thickness FM fragments were treated with/without GM-CSF. Some were preincubated with alpha-lipoic acid (LA), a known inhibitor of FM weakening. The FM fragments were then strength-tested. Separately, FM fragments were initially separated to AM and CD. AM fragments were cultured with Medium ± GM-CSF and then strength-tested. In other experiments, CD fragments were cultured with Medium, GM-CSF, LA, or LA + GM-CSF. Conditioned medium from each group was then incubated with AM. AM was then strength-tested. Matrix Metalloproteinases (MMPs) and Tissue Inhibitors of Matrix Metalloproteinases (TIMPs) were analyzed by Mutiplex Elisa.

RESULTS

GM-CSF weakened intact FM which was blocked by LA. GM-CSF did not weaken isolated AM. However, GM-CSF conditioned CD media weakened AM and this weakening was inhibited by LA. GM-CSF treatment of CD increased MMPs 2, 9, and 10, and decreased TIMPs 1-3. LA reversed these effects.

CONCLUSIONS

GM-CSF does not weaken amnion directly; GM-CSF acts on CD to increase proteases and decrease anti-proteases which secondarily weaken the amnion.

Optic Nerve Lipidomics Reveal Impaired Glucosylsphingosine Lipids Pathway in Glaucoma

Purpose

To determine major differences in lipid profile between human control and glaucomatous optic nerve. To assess major enzymes in lipid pathway if aberration is revealed for a lipid class by profiling.

Methods

Optic nerve (ON) samples were obtained from human cadaveric donors [control (n = 11) and primary open-angle glaucoma (POAG; n = 12)]; the lipids were extracted using Bligh and Dyer methods. Control and glaucoma donors were all Caucasians age 72.3 ± 5.9 and 70.3 ± 10.5 (inclusive of both sexes), respectively. Lipids were extracted after weighing the tissue; the protein amounts in the corresponding aqueous phase of organic solvent extraction were recorded. High-resolution mass spectrometry was performed using a Q-exactive mass spectrometer coupled with an EASY-nLC 1000 liquid chromatograph instrument. Bioinformatics and statistical analysis were performed using LipidSearch v.4.1 and MetaboAnalyst 4.0/STATA 14.2. Protein amounts were determined using Bradford's method. Western blot, ELISA, and immunohistochemistry utilized established protocols and were performed for protein quantification and localization, respectively. Additional donor tissues were utilized for Western blot, ELISA, and immunohistochemistry.

Results

Principal component analysis (PCA) placed control and glaucomatous ONs in two distinct groups based on analysis of lipid profiles. Total lipid, total phospholipids, total ceramide, and total sphingolipids were similar (without significant difference) between control and glaucoma. However, we found a significant increase in glucosylsphingosine in glaucoma compared to control samples. We found similar levels of glucocerebrosidase (GBA), ceramide glucosyltransferase (UGCG), decreased nonlysosomal glucocerebrosidase (GBA2), and increased lysosomal and nonlysosomal acylsphingosine amidohydrolase (ASAH1 and ASAH2) levels in glaucomatous ON compared to control.

Conclusions

We found significant differences in glucosylsphingosine lipids, consistent with decreased GBA and GBA2 and increased ASAH1 and ASAH2 immunoreactivity in glaucoma, suggesting the potential impairment of sphingolipid enzymatic pathways in lysosomal and nonlysosomal cellular compartments.

Targeting mechanotransduction mechanisms and tissue weakening signals in the human amniotic membrane

Mechanical and inflammatory signals in the fetal membrane play an important role in extracellular matrix (ECM) remodelling in order to dictate the timing of birth. We developed a mechanical model that mimics repetitive stretching of the amniotic membrane (AM) isolated from regions over the placenta (PAM) or cervix (CAM) and examined the effect of cyclic tensile strain (CTS) on mediators involved in mechanotransduction (Cx43, AKT), tissue remodelling (GAGs, elastin, collagen) and inflammation (PGE₂, MMPs). In CAM and PAM specimens, the application of CTS increased GAG synthesis, PGE₂ release and MMP activity, with concomitant reduction in collagen and elastin content. Co-stimulation with CTS and pharmacological agents that inhibit either Cx43 or AKT, differentially influenced collagen, GAG and elastin in a tissue-dependent manner. SHG confocal imaging of collagen fibres revealed a reduction in SHG intensity after CTS, with regions of disorganisation dependent on tissue location. CTS increased Cx43 and AKT protein and gene expression and the response could be reversed with either CTS, the Cx43 antisense or AKT inhibitor. We demonstrate that targeting Cx43 and AKT prevents strain-induced ECM damage and promotes tissue remodelling mechanisms in the AM. We speculate that a combination of inflammatory and mechanical factors could perturb typical mechanotransduction processes mediated by Cx43 signalling. Cx43 could therefore be a potential therapeutic target to prevent inflammation and preterm premature rupture of the fetal membranes.

Progestins Inhibit Tumor Necrosis Factor α-Induced Matrix Metalloproteinase 9 Activity via the Glucocorticoid Receptor in Primary Amnion Epithelial Cells

Progestins have been recommended for preterm birth prevention in high-risk women; however, their mechanism of action still remains an area of debate. Medroxyprogesterone acetate (MPA) has previously been shown to significantly inhibit tumor necrosis factor α (TNFα)-induced matrix metalloproteinase 9 (MMP9) messenger RNA (mRNA) expression and activity in primary amnion epithelial cells, a process that may lead to preterm premature rupture of membranes. A mechanism that explains MPA's inhibition of TNFα-induced MMP9 mRNA expression and activity in primary amnion epithelial cells is unclear since these cells lack the classic nuclear progesterone receptor but express a membrane-associated progesterone receptor-progesterone receptor membrane component 1 (PGRMC1) along with the glucocorticoid receptor (GR). Primary amnion epithelial cells harvested from healthy term pregnant women at cesarean section were treated with PGRMC1 (to knockdown PGRMC1 expression), GR (to knockdown GR expression), or control small interfering RNA (siRNA; 10 nm) for 72 hours, pretreated with ethanol or MPA (10^-6 M) for 6 hours, and then stimulated with or without TNFα 10 ng/mL for 24 hours. Real-time quantitative polymerase chain reaction and gelatin zymography were used to quantify MMP9 mRNA expression and activity, respectively. Experimental groups were compared using 1-way analysis of variance. Both TNFα-induced MMP9 mRNA expression and activity were significantly inhibited by pretreatment with MPA; however, only the inhibition of TNFα-induced MMP9 activity was partially reversed with PGRMC1 siRNA. However, GR siRNA reversed both the inhibition of TNFα-induced MMP9 mRNA expression and activity by MPA. This study demonstrates that MPA mediates its anti-inflammatory effects primarily through GR and partially through PGRMC1 in primary amnion epithelial cells.

Alpha lipoic acid in obstetrics and gynecology

Alpha-Lipoic acid (ALA) is a natural antioxidant synthetized by plants and animals, identified as a catalytic agent for oxidative decarboxylation of pyruvate and α-ketoglutarate. In this review, we analyzed the action of ALA in gynecology and obstetrics focusing in particular on neuropathic pain and antioxidant and anti-inflammatory action. A comprehensive literature search was performed in PubMed and Cochrane Library for retrieving articles in English language on the antioxidant and anti-inflammatory effects of ALA in gynecological and obstetrical conditions. ALA reduces oxidative stress and insulin resistance in women with polycystic ovary syndrome (PCOS). The association of N-acetyl cysteine (NAC), alpha-lipoic acid (ALA), and bromelain (Br) is used for prevention and treatment of endometriosis. In association with omega-3 polyunsaturated fatty acids (n-3 PUFAs) with amitriptyline is used for treatment of vestibulodynia/painful bladder syndrome (VBD/PBS). A promising area of research is ALA supplementation in patients with threatened miscarriage to improve the subchorionic hematoma resorption. Furthermore, ALA could be used in prevention of diabetic embryopathy and premature rupture of fetal membranes induced by inflamation. In conclusion, ALA can be safely used for treatment of neuropatic pain and as a dietary support during pregnancy.

Infection-induced thrombin production: a potential novel mechanism for preterm premature rupture of membranes (PPROM)

BACKGROUND

Preterm premature rupture of membranes is a leading contributor to maternal and neonatal morbidity and death. Epidemiologic and experimental studies have demonstrated that thrombin causes fetal membrane weakening and subsequently preterm premature rupture of membranes. Although blood is suspected to be the likely source of thrombin in fetal membranes and amniotic fluid of patients with preterm premature rupture of membranes, this has not been proved. Ureaplasma parvum is emerging as a pathogen involved in prematurity, which includes preterm premature rupture of membranes; however, until now, prothrombin production that has been induced directly by bacteria in fetal membranes has not been described.

OBJECTIVE

This study was designed to investigate whether Ureaplasma parvum exposure can induce prothrombin production in fetal membranes cells.

STUDY DESIGN

Primary fetal membrane cells (amnion epithelial, chorion trophoblast, and decidua stromal) or full-thickness fetal membrane tissue explants from elective, term, uncomplicated cesarean deliveries were harvested. Cells or tissue explants were infected with live Ureaplasma parvum (1×10⁵, 1×10⁶ or 1×10⁷ colony-forming units per milliliter) or lipopolysaccharide (Escherichia coli J5, L-5014; Sigma Chemical Company, St. Louis, MO; 100 ng/mL or 1000 ng/mL) for 24 hours. Tissue explants were fixed for immunohistochemistry staining of thrombin/prothrombin. Fetal membrane cells were fixed for confocal immunofluorescent staining of the biomarkers of fetal membrane cell types and thrombin/prothrombin. Protein and messenger RNA were harvested from the cells and tissue explants for Western blot or quantitative reverse transcription polymerase chain reaction to quantify thrombin/prothrombin protein or messenger RNA production, respectively. Data are presented as mean values ± standard errors of mean. Data were analyzed using 1-way analysis of variance with post hoc Dunnett's test.

RESULTS

Prothrombin production and localization were confirmed by Western blot and immunostainings in all primary fetal membrane cells and tissue explants. Immunofluorescence observations revealed a perinuclear localization of prothrombin in amnion epithelial cells. Localization of prothrombin in chorion and decidua cells was perinuclear and cytoplasmic. Prothrombin messenger RNA and protein expression in fetal membranes were increased significantly by Ureaplasma parvum, but not lipopolysaccharide, treatments in a dose-dependent manner. Specifically, Ureaplasma parvum at a dose of 1×10⁷ colony-forming units/mL significantly increased both prothrombin messenger RNA (fold changes in amnion: 4.1±1.9; chorion: 5.7±4.2; decidua: 10.0±5.4; fetal membrane: 9.2±3.0) and protein expression (fold changes in amnion: 138.0±44.0; chorion: 139.6±15.1; decidua: 56.9±29.1; fetal membrane: 133.1±40.0) compared with untreated control subjects. Ureaplasma parvum at a dose of 1×10⁶ colony-forming units/mL significantly up-regulated prothrombin protein expression in chorion cells (fold change: 54.9±5.3) and prothrombin messenger RNA expression in decidua cells (fold change: 4.4±1.9).

CONCLUSION

Our results demonstrate that prothrombin can be produced directly by fetal membrane amnion, chorion, and decidua cells. Further, prothrombin production can be stimulated by Ureaplasma parvum exposure in fetal membranes. These findings represent a potential novel underlying mechanism of Ureaplasma parvum-induced rupture of fetal membranes.

In an in-vitro model using human fetal membranes, α-lipoic acid inhibits inflammation induced fetal membrane weakening

INTRODUCTION

We established an in-vitro model for the study of human fetal membrane (FM) weakening leading to pPROM. In this model, granulocyte-macrophage colony-stimulating factor (GM-CSF) is a critical intermediate for both tumor necrosis factor-α (TNF; modeling infection/inflammation) and thrombin (modeling decidual bleeding/abruption)-induced weakening. Thus, inhibitors of FM weakening can be categorized as targeting GM-CSF production, GM-CSF downstream action, or both. Most progestogens inhibit both, except 17-α hydroxyprogesterone caproate which inhibits FM weakening at only one point, GM-CSF production. α-lipoic acid (LA), an over-the-counter dietary supplement, has also been previously shown to inhibit TNF and thrombin induced FM weakening.

OBJECTIVE

To determine the point of action of LA inhibition of FM weakening.

METHODS

FM fragments were mounted in Transwell inserts and preincubated with/without LA/24 h, then with/without addition of TNF, thrombin or GM-CSF. After 48 h, medium was assayed for GM-CSF, and FM fragments were rupture-strength tested.

RESULTS

TNF and thrombin both weakened FM and increased GM-CSF levels. GM-CSF also weakened FM. LA inhibited both TNF and thrombin induced FM weakening and concomitantly inhibited the increase in GM-CSF in a concentration-dependent manner. In addition, LA inhibited GM-CSF induced FM weakening in a concentration dependent manner.

CONCLUSIONS

LA blocks TNF and thrombin induced FM weakening at two points, inhibiting both GM-CSF production and downstream action. Thus, we speculate that LA may be a potential standalone therapeutic agent, or supplement to current therapy for prevention of pPROM related spontaneous preterm birth, if preclinical studies to examine feasibility and safety during pregnancy are successfully accomplished.

In an in-vitro model using human fetal membranes, 17-α hydroxyprogesterone caproate is not an optimal progestogen for inhibition of fetal membrane weakening

BACKGROUND

The progestogen 17-α hydroxyprogesterone caproate (17-OHPC) is 1 of only 2 agents recommended for clinical use in the prevention of spontaneous preterm delivery, and studies of its efficacy have been conflicting. We have developed an in-vitro model to study the fetal membrane weakening process that leads to rupture in preterm premature rupture of the fetal membranes (pPROM). Inflammation/infection associated with tumor necrosis factor-α (TNF-α) induction and decidual bleeding/abruption associated thrombin release are leading causes of preterm premature rupture of the fetal membranes. Both agents (TNF-α and thrombin) cause fetal membrane weakening in the model system. Furthermore, granulocyte-macrophage colony-stimulating factor (GM-CSF) is a critical intermediate for both TNF-α and thrombin-induced fetal membrane weakening. In a previous report, we demonstrated that 3 progestogens, progesterone, 17-alpha hydroxyprogesterone (17-OHP), and medroxyprogesterone acetate (MPA), each inhibit both TNF-α- and thrombin-induced fetal membrane weakening at 2 distinct points of the fetal membrane weakening pathway. Each block both the production of and the downstream action of the critical intermediate granulocyte-macrophage colony-stimulating factor.

OBJECTIVE

The objective of the study was to characterize the inhibitory effects of 17-OHPC on TNF-α- and thrombin-induced fetal membrane weakening in vitro.

STUDY DESIGN

Full-thickness human fetal membrane fragments from uncomplicated term repeat cesarean deliveries were mounted in 2.5 cm Transwell inserts and cultured with/without 17-alpha hydroxyprogesterone caproate (10^-9 to 10^-7 M). After 24 hours, medium (supernatant) was removed and replaced with/without the addition of tumor necrosis factor-alpha (20 ng/mL) or thrombin (10 U/mL) or granulocyte-macrophage colony-stimulating factor (200 ng/mL). After 48 hours of culture, medium from the maternal side compartment of the model was assayed for granulocyte-macrophage colony-stimulating factor and the fetal membrane fragments were rupture strength tested.

RESULTS

Tumor necrosis factor-alpha and thrombin both weakened fetal membranes (43% and 62%, respectively) and increased granulocyte-macrophage colony-stimulating factor levels (3.7- and 5.9-fold, respectively). Pretreatment with 17-alpha hydroxyprogesterone caproate inhibited both tumor necrosis factor-alpha- and thrombin-induced fetal membrane weakening and concomitantly inhibited the induced increase in granulocyte-macrophage colony-stimulating factor in a concentration-dependent manner. However, contrary to our prior reports regarding progesterone and other progestogens, 17-alpha hydroxyprogesterone caproate did not also inhibit granulocyte-macrophage colony-stimulating factor-induced fetal membrane weakening.

CONCLUSION

17-Alpha hydroxyprogesterone caproate blocks tumor necrosis factor-alpha- and thrombin-induced fetal membrane weakening by inhibiting the production of granulocyte-macrophage colony-stimulating factor. However, 17-alpha hydroxyprogesterone caproate did not also inhibit granulocyte-macrophage colony-stimulating factor-induced weakening. We speculate that progestogens other than 17-alpha hydroxyprogesterone caproate may be more efficacious in preventing preterm premature rupture of the fetal membranes-related spontaneous preterm birth.

A distinct mechanism of senescence activation in amnion epithelial cells by infection, inflammation, and oxidative stress

PROBLEM

We investigated p38MAPK activation-induced fetal membrane cell senescence in response to inflammation (tumour necrosis factor-alpha [TNF-α]) and infection (lipopolysaccharide [LPS]), factors associated with spontaneous preterm birth.

METHOD OF STUDY

Primary amnion epithelial cells (AECs) were exposed to TNF-α, 50 ng/mL and LPS, 100 ng/mL. Cigarette smoke extract (CSE), a known OS inducer, was used as positive control. AECs were cotreated with the antioxidant N-acetyl cysteine (NAC) and p38MAPK inhibitor SB203580 to determine the effect of OS and p38MAPK. Western blot analysis was performed for active (Phospho-p38MAPK) and total p38MAPK. Senescence was determined by flow cytometry, and culture supernatants were tested for IL-6 using ELISA.

RESULTS

TNF-α, but not LPS, increased p38MAPK activation compared to untreated cells (P = .01). The number of senescent cells and senescence-associated IL-6 was higher in both TNF-α and LPS-treated cells compared to control (P = .001, P = .01, respectively). Antioxidant NAC inhibited p38MAPK activation by TNF-α. p38MAPK inhibitor SB203580 reduced the development of senescence and IL-6 by TNF-α and LPS. CSE treatment validated our current data.

CONCLUSION

TNF-α caused OS-mediated p38MAPK induction, senescence, and IL-6 increase from AECs. LPS also induced senescence and IL-6 increase. Inflammatory and infectious factors may cause premature fetal cell senescence contributing to preterm birth pathophysiology.

Immune Modifications in Fetal Membranes Overlying the Cervix Precede Parturition in Humans

In humans, parturition is currently viewed as an intrauterine outbreak of inflammation, accompanied by a massive release of proinflammatory cytokines at the maternal-fetal interface that comprises the maternal decidua, placenta, and fetal membranes. At term, fetal membranes overlying the cervix, the future site of rupture, show altered morphology and are termed the zone of altered morphology (ZAM). These alterations occur in normal fetal membranes during late pregnancy, in preparation for labor. In this study, transcriptome, flow cytometry, electron microscopy, and immunohistochemistry analyses collectively highlight a local shift in gene expression and lymphocyte activation in the ZAM. Just before labor, we show that highly polymorphic HLA-A, -B, and -C determinants of fetal origin are selectively exposed in the ZAM to the maternal immune system. A graft rejection-like program occurs in the ZAM, which involves 1) the activation of cytotoxic decidual NK cells, and 2) the decline of decidual immunotolerant M2-like macrophages. Comparison with a prior cohort of fetal membranes shows that acute inflammation only takes place after these first steps of immune modifications. Our results therefore strongly argue in favor of local immune remodeling at the onset of parturition.

Thrombin-Induced Inflammation in Human Decidual Cells Is Not Affected By Heparin

OBJECTIVE

Thrombin (Thr) generation at the uteroplacental interface induces inflammation and weakens fetal membranes. Tissue factor (TF) is a powerful procoagulant that is increased by Thr in decidual cells (DCs). The TF expression may play an important role in modulating Thr-induced inflammation. The purpose of this study was to assess the effect of heparin, including nonanticoagulant (desulfated) heparins, on basal and Thr-induced expression of TF and inflammatory cytokines in DCs.

METHODS

Fetal membranes were collected from term pregnancies undergoing unlabored cesarean delivery and then DCs were isolated and cultured. Third passage DCs were conditioned in defined media for 1 week and then treated with 1 of the 4 heparins (enoxaparin, unfractionated heparin, and 2 desulfated heparins) with and without Thr (2.5 U/mL) for 24 hours. Supernatant levels of interleukin (IL) 6, IL-8, IL-10, tumor necrosis factor α, and interferon γ (IFN-γ) were determined by enzyme-linked immunosorbent assay. Western blots were performed on cell lysates to determine TF expression. A Kruskal-Wallis test was used to compare cytokine concentrations and normalized TF expression among treatments.

RESULTS

Treatment of DCs with Thr alone increased the expression of TF, IL-6, IL8, IL-10, and IFN-γ compared to basal levels ( P < .05 for each). Cotreatment of DCs with Thr and any of the tested heparins did not decrease the expression of TF or inflammatory cytokines compared to treatment with Thr alone.

DISCUSSION

Heparins do not appear to affect basal or Thr-induced expression of TF or inflammatory cytokines in human term DCs. Additional work is needed to determine whether nonanticoagulant heparins can reduce inflammation and membrane weakening due to bleeding in pregnancy.

[Association between interleukin-1β C+3953T and genetic susceptibility to spontaneous preterm birth: a case-control study]

OBJECTIVE

To study the association between interleukin-1β (IL-1β) C+3953T and genetic susceptibility to spontaneous preterm birth (SPTB).

METHODS

In this case-control study, 753 SPTB neonates were enrolled in the case group and 681 full-term neonates were enrolled in the control group. The latest Sequenom MassARRAY®SNP detection technique was used for the typing of single nucleotide polymorphisms (SNP) of IL-1β C+3953T.

RESULTS

Compared with those carrying CC genotype of IL-1β C+3953T, the neonates who carried at least one T allele (CT+TT genotype) had significantly increased risks of SPTB, SPTB complicated by premature rupture of membranes, and mild preterm birth.

CONCLUSIONS

In the Chinese population, IL-1β C+3953T has significant genetic association with an increased risk of SPTB. The identification of this SNP helps to prevent SPTB and clarify the causes and pathogenesis of SPTB.

Human fetal membranes at term: Dead tissue or signalers of parturition?

Various endocrine, immune, and mechanical factors produced by feto-maternal compartments at term increase intrauterine inflammatory loads to induce labor. The role of fetal (placental) membranes (amniochorion) as providers of parturition signals has not been well investigated. Fetal membranes line the intrauterine cavity and grow with and protect the fetus. Fetal membranes exist as an entity between the mother and fetus and perform unique functions during pregnancy. Membranes undergo a telomere-dependent p38 MAPK-induced senescence and demonstrate a decline in functional and mechanical abilities at term, showing signs of aging. Fetal membrane senescence is also allied with completion of fetal maturation at term as the fetus readies for delivery, which may also indicate the end of independent life and longevity of fetal membranes as their functional role concludes. Fetal membrane senescence is accelerated at term because of oxidative stress and increased stretching. Senescent fetal membranes cells produce senescence-associated secretory phenotype (SASP-inflammation) and also release proinflammatory damage-associated molecular patterns (DAMPs), namely HMGB1 and cell-free fetal telomere fragments. In a feedback loop, SASP and DAMPs increase senescence and enhance the inflammatory load to promote labor. Membranes increase the inflammatory load to disrupt homeostatic balance to transition quiescent uterine tissues toward a labor phenotype. Therefore, along with other well-described labor-promoting signals, senescent fetal membranes may also contribute to human term parturition.

The physiology of fetal membrane weakening and rupture: Insights gained from the determination of physical properties revisited

Rupture of the fetal membranes (FM) is precipitated by stretch forces acting upon biochemically mediated, pre-weakened tissue. Term FM develop a para-cervical weak zone, characterized by collagen remodeling and apoptosis, within which FM rupture is thought to initiate. Preterm FM also have a weak region but are stronger overall than term FM. Inflammation/infection and decidual bleeding/abruption are strongly associated with preterm premature FM rupture (pPROM), but the specific mechanisms causing FM weakening-rupture in pPROM are unknown. There are no animal models for study of FM weakening and rupture. Over a decade ago we developed equipment and methodology to test human FM strength and incorporated it into a FM explant system to create an in-vitro human FM weakening model system. Within this model TNF (modeling inflammation) and Thrombin (modeling bleeding) both weaken human FM with concomitant up regulation of MMP9 and cellular apoptosis, mimicking the characteristics of the spontaneous FM rupture site. The model has been enhanced so that test agents can be applied directionally to the choriodecidual side of the FM explant consistent with the in-vivo situation. With this enhanced system we have demonstrated that the pathways involving inflammation/TNF and bleeding/Thrombin induced FM weakening overlap. Furthermore GM-CSF production was demonstrated to be a critical common intermediate step in both the TNF and the Thrombin induced FM weakening pathways. This model system has also been used to test potential inhibitors of FM weakening and therefore pPROM. The dietary supplement α-lipoic acid and progestogens (P4, MPA and 17α-hydroxyprogesterone) have been shown to inhibit both TNF and Thrombin induced FM weakening. The progestogens act at multiple points by inhibiting both GM-CSF production and GM-CSF action. The use of a combined biomechanical/biochemical in-vitro human FM weakening model system has allowed the pathways of fetal membrane weakening to be delineated, and agents that may be of clinical use in inhibiting these pathways to be tested.

Progesterone, Inflammatory Cytokine (TNF-α), and Oxidative Stress (H2O2) Regulate Progesterone Receptor Membrane Component 1 Expression in Fetal Membrane Cells

Progesterone receptor membrane component 1 (PGRMC1) is an important novel mediator of progesterone (P4) function in fetal membrane cells. We demonstrated previously that PGRMC1 is differentially expressed in fetal membranes among pregnancy subjects and diminished in preterm premature rupture of membrane subjects. In the current study, we aim to elucidate whether PGRMC1 expression is regulated by P4, tumor necrosis factor α (TNF-α), and H2O2 in fetal membrane cells. Primary cultured membrane cells were serum starved for 24 hours followed by treatments of P4, 17 hydroxyprogesterone caproate, and medroxyprogesterone 17 acetate (MPA) at 10(-7) mol/L with ethanol as vehicle control; TNF-α at 10, 20, and 50 ng/mL with phosphate-buffered saline (PBS) as control; and H2O2 at 10 and 100 μmol/L with culture media as control for 24, 48, and 72 hours. The messenger RNA (mRNA) and protein expression of PGRMC1 was quantified using polymerase chain reaction and Western blotting, respectively. We found that PGRMC1 protein expression was regulated by MPA, TNF-α, and H2O2 in a dose-dependent manner. This regulation is also specific to the type of cell (amnion, chorion, or decidua). The upregulation of PGRMC1 by MPA might be mediated through glucocorticoid receptor (GR) demonstrated using amnion and chorion cells model with GR knockdown by specific small interfering RNA transfection. The mRNA expression of PGRMC1 was decreased by H2O2 (100 μmol/L) treatment in amnion cells, which might ultimately result in downregulation of PGRMC1 protein as our data demonstrated. None of other treatments changed PGRMC1 mRNA level in these cells. We conclude that these stimuli act as regulatory factors of PGRMC1 in a cell-specific manner.

The role of decidual cells in uterine hemostasis, menstruation, inflammation, adverse pregnancy outcomes and abnormal uterine bleeding

BACKGROUND

Human pregnancy requires robust hemostasis to prevent hemorrhage during extravillous trophoblast (EVT) invasion of the decidualized endometrium, modification of spiral arteries and post-partum processes. However, decidual hemorrhage (abruption) can occur throughout pregnancy from poorly transformed spiral arteries, causing fetal death or spontaneous preterm birth (PTB), or it can promote the aberrant placentation observed in intrauterine growth restriction (IUGR) and pre-eclampsia; all leading causes of perinatal or maternal morbidity and mortality. In non-fertile cycles, the decidua undergoes controlled menstrual bleeding. Abnormal uterine bleeding (AUB) accompanying progestin-only, long-acting, reversible contraception (pLARC) accounts for most discontinuations of these safe and highly effective agents, thereby contributing to unwanted pregnancies and abortion. The aim of this study was to investigate the role of decidual cells in uterine hemostasis, menstruation, inflammation, adverse pregnancy outcomes and abnormal uterine bleeding.

METHODS

We conducted a critical review of the literature arising from PubMed searches up to December 2015, regarding in situ and in vitro expression and regulation of several specific proteins involved in uterine hemostasis in decidua and cycling endometrium. In addition, we discussed clinical and molecular mechanisms associated with pLARC-induced AUB and pregnancy complications with abruptions, chorioamnionitis or pre-eclampsia.

RESULTS

Progestin-induced decidualization of estradiol-primed human endometrial stromal cells (HESCs) increases in vivo and in vitro expression of tissue factor (TF) and type-1 plasminogen activator inhibitor (PAI-1) while inhibiting plasminogen activators (PAs), matrix metalloproteinases (MMPs), and the vasoconstrictor, endothelin-1 (ET-1). These changes in decidual cell-derived regulators of hemostasis, fibrinolysis, extracellular matrix (ECM) turnover, and vascular tone prevent hemorrhage during EVT invasion and vascular remodeling. In non-fertile cycles, progesterone withdrawal reduces TF and PAI-1 while increasing PA, MMPs and ET-1, causing menstrual-associated bleeding, fibrinolysis, ECM degradation and ischemia. First trimester decidual hemorrhage elicits later adverse outcomes including pregnancy loss, pre-eclampsia, abruption, IUGR and PTB. Decidual hemorrhage generates excess thrombin that binds to decidual cell-expressed protease-activated receptors (PARs) to induce chemokines promoting shallow placentation; such bleeding later in pregnancy generates thrombin to down-regulate decidual cell progesterone receptors and up-regulate cytokines and MMPs linked to PTB. Endometria of pLARC users display ischemia-induced excess vasculogenesis and progestin inhibition of spiral artery vascular smooth muscle cell proliferation and migration leading to dilated fragile vessels prone to bleeding. Moreover, aberrant TF-derived thrombin signaling also contributes to the pathogenesis of endometriosis via induction of angiogenesis, inflammation and cell survival.

CONCLUSION

Perivascular decidualized HESCs promote endometrial hemostasis during placentation yet facilitate menstruation through progestational regulation of hemostatic, proteolytic, and vasoactive proteins. Pathological endometrial hemorrhage elicits excess local thrombin generation, which contributes to pLARC associated AUB, endometriosis and adverse pregnancy outcomes through several biochemical mechanisms.

Oxidative stress damage-associated molecular signaling pathways differentiate spontaneous preterm birth and preterm premature rupture of the membranes

STUDY HYPOTHESIS

In women with preterm premature rupture of the membranes (PPROM), increased oxidative stress may accelerate premature cellular senescence, senescence-associated inflammation and proteolysis, which may predispose them to rupture.

STUDY FINDING

We demonstrate mechanistic differences between preterm birth (PTB) and PPROM by revealing differences in fetal membrane redox status, oxidative stress-induced damage, distinct signaling pathways and senescence activation.

WHAT IS KNOWN ALREADY

Oxidative stress-associated fetal membrane damage and cell cycle arrest determine adverse pregnancy outcomes, such as spontaneous PTB and PPROM.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

Fetal membranes and amniotic fluid samples were collected from women with PTB and PPROM. Molecular, biochemical and histologic markers were used to document differences in oxidative stress and antioxidant enzyme status, DNA damage, secondary signaling activation by Ras-GTPase and mitogen-activated protein kinases, and activation of senescence between membranes from the two groups.

MAIN RESULTS AND THE ROLE OF CHANCE

Oxidative stress was higher and antioxidant enzymes were lower in PPROM compared with PTB. PTB membranes had minimal DNA damage and showed activation of Ras-GTPase and ERK/JNK signaling pathway with minimal signs of senescence. PPROM had higher numbers of cells with DNA damage, prosenescence stress kinase (p38 MAPK) activation and signs of senescence.

LIMITATIONS, REASONS FOR CAUTION

Samples were obtained retrospectively after delivery. The markers of senescence that we tested are specific but are not sufficient to confirm senescence as the pathology in PPROM.

WIDER IMPLICATIONS OF THE FINDINGS

Oxidative stress-induced DNA damage and senescence are characteristics of fetal membranes from PPROM, compared with PTB with intact membranes. PTB and PPROM arise from distinct pathophysiologic pathways. Oxidative stress and oxidative stress-induced cellular damages are likely determinants of the mechanistic signaling pathways and phenotypic outcome.

STUDY FUNDING AND COMPETING INTERESTS

This study is supported by developmental funds to Dr R. Menon from the Department of Obstetrics and Gynecology at The University of Texas Medical Branch at Galveston and funds to Dr M. Kacerovský from the Ministry of Health Czech Republic (UHHK, 001799906). The authors report no conflict of interest.

In-vivo stretch of term human fetal membranes

INTRODUCTION

Fetal membranes (FM) usually fail prior to delivery during term labor, but occasionally fail at preterm gestation, precipitating preterm birth. To understand the FM biomechanical properties underlying these events, study of the baseline in-vivo stretch experienced by the FM is required. This study's objective was to utilize high resolution MRI imaging to determine in-vivo FM stretch.

METHODS

Eight pregnant women (38.4 ± 0.4wks) underwent abdominal-pelvic MRI prior to (2.88 ± 0.83d) caesarean delivery. Software was utilized to determine the total FM in-vivo surface area (SA) and that of its components: placental disc and reflected FM. At delivery, the SA of the disc and FM in the relaxed state were measured. In-vivo (stretched) to delivered SA ratios were calculated. FM fragments were then biaxially stretched to determine the force required to re-stretch the FM back to in-vivo SA.

RESULTS

Total FM SA, in-vivo vs delivered, was 2135.51 ± 108.47 cm(2) vs 842.59 ± 35.86 cm(2); reflected FM was 1778.42 ± 107.39 cm(2) vs 545.41 ± 22.90 cm(2), and disc was 357.10 ± 28.08 cm(2) vs 297.18 ± 22.14 cm(2). The ratio (in-vivo to in-vitro SA) of reflected FM was 3.26 ± 0.11 and disc was 1.22 ± 0.10. Reflected FM re-stretched to in-vivo SA generated a tension of 72.26 N/m, corresponding to approximate pressure of 15.4 mmHg. FM rupture occurred at 295.08 ± 31.73 N/m corresponding to approximate pressure of 34 mmHg. Physiological SA was 70% of that at rupture.

DISCUSSION

FM are significantly distended in-vivo. FM collagen fibers were rapidly recruited once loaded and functioned near the failure state during in-vitro testing, suggesting that, in-vivo, minimal additional (beyond physiological) stretch may facilitate rapid, catastrophic failure.

Autophagy, which is decreased in labouring fetal membranes, regulates IL-1β production via the inflammasome

INTRODUCTION

IL-1β plays a vital role in the terminal processes of human labour and delivery. Inflammasome activation is required to process pro IL-1β to an active, secreted molecule. Recent studies have shown that autophagy regulates IL-1β via the inflammasome. The aims were to determine the effect of (i) human spontaneous term and preterm labour on the expression of autophagy proteins in fetal membranes; and (ii) autophagy inhibition on IL-1β release.

METHODS

Fetal membranes, from term and preterm, were obtained from non-labouring and labouring women. Tissue explants were used to determine the effect of inhibition of autophagy on IL-1β secretion.

RESULTS

Expression of the autophagy proteins Beclin-1, Atg3, Atg5, Atg7, Atg12, Atg16L1 were lower after spontaneous term labour. Beclin-1 and Atg7 expression were lower after spontaneous preterm labour. Beclin-1, Atg3, and Atg7 expression were lower after preterm pre-labour rupture of membranes (PPROM) compared to preterm with intact membranes. LC3B-I expression was higher after spontaneous term and preterm labour and with PPROM; there was no difference in LC3B-II expression between the two groups. The autophagy inhibitor LY290042 increased IL-1β secretion in the presence of bacterial endotoxin LPS; IL-1β secretion was ameliorated in the presence inflammasome inhibitors.

DISCUSSION

Autophagy is decreased in fetal membranes after spontaneous labour and delivery, and PPROM. Inhibition of autophagy regulates the secretion of IL-1β via inflammasome activation. IL-1β is a major contributor to the pathophysiology of spontaneous preterm birth. Therefore activation of autophagy may be a potential therapeutic mechanism to delay or prevent infection-induced preterm birth.

Thrombin Generation by Fetoscopic Trauma to the Fetal Membranes: An in vivo and in vitro Study

OBJECTIVE

We first aimed to investigate in vivo thrombin generation induced by fetoscopy, and second we used term membrane explants for measurement of thrombin generation, thrombin receptor location and induction of selected matrix metalloproteinases (MMPs) in tissue culture.

MATERIALS AND METHODS

In vivo study (37 cases): samples of amniotic fluid were taken at the beginning and end of fetoscopy (mean gestational age 26.7 weeks) and analyzed by ELISA for thrombin-antithrombin complexes. In vitro study: fetal membranes were put in culture and punctured for measurement of thrombin generation by calibrated automated thrombography and ELISA. Induction of MMP-9 and MMP-2 was analyzed by zymography. PAR-1 was localized by immunohistochemistry.

RESULTS

No significant increase in thrombin-antithrombin was measured in amniotic fluid obtained during fetoscopy. In vitro, thrombin generation induced by needle trauma of membrane cultures is correlated to the amount of plasma. Activity of MMP-9 but not MMP-2 was elevated in cultured membranes but could not be inhibited by a thrombin inhibitor. On histology, the thrombin receptor PAR-1 was located in the chorion and decidua, but not in the amnion.

DISCUSSION

Despite the influence of thrombin on punctured fetal membranes in vitro, the role of thrombin in iatrogenic preterm premature rupture of membranes is questionable.

Progesterone inhibits in vitro fetal membrane weakening

OBJECTIVE

Inflammation/infection and abruption are leading causes of preterm premature rupture of the membranes. Recently, we identified granulocyte-macrophage colony-stimulating factor (GM-CSF) as a critical mediator of both tumor necrosis factor-α- (TNF; modeling inflammation) and thrombin-induced (modeling abruption) weakening of the fetal membranes. We found that (1) TNF and thrombin both induced GM-CSF in the choriodecidua, (2) blockade of GM-CSF action with neutralizing antibodies inhibited both TNF- and thrombin-induced fetal membrane weakening, and (3) GM-CSF alone induced fetal membrane weakening. GM-CSF is thus part of an overlap of the inflammation and abruption-induced fetal membrane weakening pathways. The effects of progesterone analogs on the pathways by which fetal membranes are weakened have not been investigated. We examined the effects of progesterone, medroxyprogesterone acetate (MPA) and 17α-hydroxyprogesterone (HP) on TNF- and thrombin-induced fetal membrane weakening.

STUDY DESIGN

Full-thickness fetal membranes from uncomplicated term repeat cesarean deliveries were mounted in Transwell inserts in Minimum Essential Medium alpha and incubated at 37°C in 5% CO2. The choriodecidua side of the fetal membrane fragments were preincubated with progesterone, MPA, HP, or vehicle for 24 hours. Fetal membranes were then exposed to TNF, thrombin, or GM-CSF on the choriodecidua side for an additional 48 hours. The fetal membrane tissues were then strength tested, and medium from the choriodecidua and amnion compartments was assayed for GM-CSF content.

RESULTS

TNF and thrombin both weakened fetal membranes and elevated media GM-CSF levels on the choriodecidua side of the fetal membrane. Pretreatment with progesterone, MPA, or HP inhibited both TNF- and thrombin-induced fetal membrane weakening and also inhibited the induced increase in GM-CSF. GM-CSF decreased fetal membrane rupture strength by 68%, which was inhibited by progestogen pretreatment with a potency order: progesterone <MPA <HP.

CONCLUSION

Progestogen pretreatment blocks TNF- and thrombin-induced fetal membrane weakening by inhibiting both the production and action of GM-CSF. These findings are consistent with the administration of progestogens in the prevention of preterm premature rupture of the membranes.

The Effect of Progestins on Tumor Necrosis Factor α-Induced Matrix Metalloproteinase-9 Activity and Gene Expression in Human Primary Amnion and Chorion Cells In Vitro

BACKGROUND

Current treatment modalities for preventing preterm premature rupture of membranes are limited, but progestins may play a role. Tumor necrosis factor α (TNFα) enhances matrix metalloproteinase-9 (MMP-9) gene expression and activity in fetal membranes, contributing to membrane weakening and rupture. We previously demonstrated that progestins attenuate TNFα-induced MMP-9 activity in a cytotrophoblast cell line. However, whether they have a similar effect in primary amnion and chorion cells of fetal membranes is unknown. In this study, we evaluated the effect of progestins on basal and TNFα-induced MMP-9 activity and gene expression in primary chorion and amnion cells harvested from the fetal membranes of term nonlaboring patients.

METHODS

Primary amnion and chorion cells were isolated from fetal membranes obtained from term uncomplicated nonlaboring patients following elective cesarean delivery (n = 11). Confluent primary amnion and chorion cell cultures were both pretreated with vehicle (control), progesterone (P4), 17α-hydroxyprogesterone caproate (17P), or medroxyprogesterone acetate (MPA) at 10 M concentration for 6 hours followed by stimulation with TNFα at 10 ng/mL for an additional 24 hours. Cell cultures pretreated with the vehicle only served as the unstimulated control and the vehicle stimulated with TNFα served as the stimulated control. Both controls were assigned a value of 100 units. Cell culture medium was harvested for MMP-9 enzymatic activity quantification using gelatin zymography. Total RNA was extracted for quantifying MMP-9 gene expression using real-time quantitative PCR. Basal MMP-9 activity and gene expression data were normalized to the unstimulated control. TNFα-stimulated MMP-9 activity and gene expression were normalized to the stimulated control. The primary outcome was the effect of progestins on TNFα-induced MMP-9 enzymatic activity in term human primary amnion and chorion cells in vitro. Secondary outcomes included the effect of progestin therapy on TNFα-induced MMP-9 gene expression and on basal MMP-9 activity and gene expression in primary amnion and chorion cells in vitro.

RESULTS

Primary cells were harvested from 11 patients. Compared with the unstimulated control, TNFα increased MMP-9 activity (P = 0.005 versus control in primary amnion cells and P < 0.001 versus control in primary chorion cells) and MMP-9 gene expression (P = 0.030 versus control in primary amnion cells, P < 0.001 versus control in primary chorion cells). Compared with the unstimulated controls, MPA, but not P4 or 17P, reduced basal MMP-9 activity [mean difference (95% CI) -49.6 (-81.9, -17.3) units, P = 0.001] and gene expression [mean difference (95% CI) -53.4 (-105.9, -0.9) units, P = 0.045] in primary amnion cells. Compared with the stimulated control, MPA also reduced TNFα-induced MMP-9 activity [mean difference (95% CI) -69.0 (-91.8, -46.3) units, P < 0.001] and gene expression [mean difference (95% CI) -86.0 (-120.7, -51.3) units, P < 0.001] in primary amnion cells. Progestin pretreatment had no significant effect on basal or TNFα-induced MMP-9 activity and gene expression in primary chorion cells.

CONCLUSIONS

The inhibitory effect of MPA on both basal and TNFα-induced MMP-9 activity and gene expression in primary amnion cells demonstrate a possible mechanism by which progestins may prevent fetal membrane weakening leading to preterm premature rupture of membranes.

The poly(adenosine diphosphate-ribose) polymerase inhibitor PJ34 reduces pulmonary ischemia-reperfusion injury in rats

Supplemental digital content is available in the text.

Background

Ischemia-reperfusion (I/R) injury after lung transplantation causes alveolar damage, lung edema, and acute rejection. Poly(adenosine diphosphate-ribose) polymerase (PARP) is a single-stranded DNA repair enzyme that induces apoptosis and necrosis after DNA damage caused by reactive oxygen species. We evaluated tissue protective effects of the PARP inhibitor (PARP-i) PJ34 against pulmonary I/R injury.

Methods

Rats (total n=45) underwent a thoracotomy with left hilar isolation and saline administration (sham group) or thoracotomy with hilar clamping and saline administration (I/R group) or PJ34 administration (PARP-i group). Parameters were measured for 7 days after reperfusion.

Results

Pathologic analysis revealed that reperfusion injury was drastically suppressed in the PARP-i group 2 days after reperfusion. Terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick-end labeling–positive cells were significantly decreased in the PARP-i group compared to the I/R group (P<0.05). Accordingly, the wet-to-dry lung ratio in the I/R group was significantly higher compared with the PARP-i group (P=0.025). Four hours after reperfusion, serum tissue necrosis factor-α and interleukin-6 were significantly suppressed in the PARP-i group compared with the I/R group (P<0.05). Serum derivatives of reactive oxygen metabolites increased quickly and remained high in the I/R and PARP-i groups from 4 hr until 7 days after reperfusion. Interestingly, the serum biologic antioxidant potential in the PARP-i group was significantly higher than that in the I/R group from day 2 until day 7.

Conclusion

The PARP-i decreased inflammation and tissue damage caused by pulmonary I/R injury. These beneficial effects of the PARP-i may be correlated with its antioxidative efficacy.

Decidual GM-CSF is a critical common intermediate necessary for thrombin and TNF induced in-vitro fetal membrane weakening

INTRODUCTION

Inflammation/infection and decidual bleeding/abruption are highly associated with pPROM. As no animal model for pPROM exists, we have developed an in-vitro model system for the study of human fetal membrane (FM) weakening/rupture. Using it we have demonstrated that both TNF/IL-1 (modeling inflammation) and thrombin (modeling bleeding) weaken full thickness FM in a dose dependent manner concomitant with inducing biochemical changes similar to those seen in the FM physiological weak zone.

METHODS

As the physiological site of infection and bleeding is the choriodecidua (CD), we modified our model system with full thickness FM tissue mounted on modified Transwell culture inserts to permit directional TNF/thrombin exposure on the decidua only (rather than both sides of the FM). After incubation, medium was sampled separately from the CD facing (maternal side) or from the amnion facing (fetal side) compartments and probed for cytokine release and confirmed with western blots. The FM was strength tested within the insert.

RESULTS

Full-thickness FM fragments exposed to TNF or thrombin on CD side only showed dose dependent weakening and biochemical changes consistent with previous reports. Concomitantly, GM-CSF increased markedly on the CD but not the amnion side. Numerous proteases including MMP1 and MMP3 also increased on the CD side. Pre-incubation with GM-CSF antibody blocked both thrombin and TNF induced weakening. Finally, GM-CSF weakened FM in a dose dependent manner.

DISCUSSION

GM-CSF is a critical common intermediate in the thrombin and TNF FM weakening pathways.

About Puncture Testing Applied for Mechanical Characterization of Fetal Membranes

Puncture testing has been applied in several studies for the mechanical characterization of human fetal membrane (FM) tissue, and significant knowledge has been gained from these investigations. When comparing results of mechanical testing (puncture, inflation, and uniaxial tension), we have observed discrepancies in the rupture sequence of FM tissue and significant differences in the deformation behavior. This study was undertaken to clarify these discrepancies. Puncture experiments on FM samples were performed to reproduce previous findings, and numerical simulations were carried out to rationalize particular aspects of membrane failure. The results demonstrate that both rupture sequence and resistance to deformation depend on the samples' fixation. Soft fixation leads to slippage in the clamping, which reduces mechanical loading of the amnion layer and results in chorion rupturing first. Conversely, the stiffer, stronger, and less extensible amnion layer fails first if tight fixation is used. The results provide a novel insight into the interpretation of ex vivo testing as well as in vivo membrane rupture.

Synergy and interactions among biological pathways leading to preterm premature rupture of membranes

Preterm premature rupture of membranes (PPROM) occurs in 1% to 2% of births. Impact of PPROM is greatest in low- and middle-income countries where prematurity-related deaths are most common. Recent investigations identify cytokine and matrix metalloproteinase activation, oxidative stress, and apoptosis as primary pathways to PPROM. These biological processes are initiated by heterogeneous etiologies including infection/inflammation, placental bleeding, uterine overdistention, and genetic polymorphisms. We hypothesize that pathways to PPROM overlap and act synergistically to weaken membranes. We focus our discussion on membrane composition and strength, pathways linking risk factors to membrane weakening, and future research directions to reduce the global burden of PPROM.

Histological evidence of oxidative stress and premature senescence in preterm premature rupture of the human fetal membranes recapitulated in vitro

Preterm prelabor rupture of the membranes (pPROM) may lead to preterm births (PTBs). We investigated premature senescence of fetal membranes in women with pPROM and spontaneous PTB with intact membranes (<34 weeks) and the inducibility fetal membrane senescence phenotype by oxidative stress in vitro. IHC was performed for p53, p21, and phospho (p)-p38 mitogen-activated protein kinase (MAPK) as markers of senescence phenotype in pPROM, PTBs, and term births. Term fetal membranes were exposed to cigarette smoke extract to induce oxidative stress. Western blots documented p-p53 and p-p38 MAPK. Transmission electron microscopy assessed cellular morphologic features in clinical and cigarette smoke extract-treated membranes. A total of 80% of pPROM cells and >60% of term cells were positive for all three senescence phenotype markers, and concentrations were higher than in PTBs (P < 0.05). p53 staining was comparable in membranes from PTB and term birth pregnancies, whereas only <30% and <45% of cells were positive for p21 and p38 MAPK, respectively. In vitro cigarette smoke extract exposure increased p-p38 MAPK without any detectable change in p-p53 MAPK. Enlargement of organelles consistent with senescence phenotype was evident in pPROM and term membranes in vivo and after cigarette smoke extract treatment in vitro but was less apparent in PTBs. Histologic and biochemical resemblance of pPROM and term membranes suggests premature senescence of the membranes is a mechanistic feature in pPROM, and this can be phenocopied in an in vitro model.